Cancer is a life-threatening concern worldwide. Sensitive and early-stage diagnostics of different cancer types can make it possible for patients to get through the best available treatment options to combat this menace. Among several new detection methods, aptamer-based biosensors (aptasensors) have recently shown promising results in terms of sensitivity, identification, or detection of either cancerous cells or the associated biomarkers. In this mini-review, we have summarized the most recent (2016–2020) developments in different approaches belonging to optical aptasensor technologies being widely employed for their simple operation, sensitivity, and early cancer diagnostics. Finally, we shed some light on limitations, advantages, and current challenges of aptasensors in clinical diagnostics, and we elaborated on some future perspectives. In anotn vitro) . ConsequOligonucleotide aptamers are single-stranded, short, nucleic acid (DNA or RNA) sequences with an ability to rearrange into a three-dimensional unique structure for highly specific binding to their particular targets ranging from proteins , 9 to evOptical methods are advantageous because they show a quick response, simple operation, and high sensitivity. Optical aptasensors involve aptamers as a biorecognition element along with various optical approaches as signal transduction element . Opticalin vivo cancer imaging that not only can activate fluorescence signals as a result of interaction with its analyte but also releases the drug  sources into electrochemiluminescence (ECL) and chemiluminescence (CL). Both are widely used in the development of aptasensors employed in cancer biomarkers detection . Severalvia specific interactions that can be further processed by their unique localized surface plasmon resonance (LSPR) spectra. Their biosensor can be employed to detect human breast cancer at early stages (Surface plasmon resonance (SPR) based biosensing is advantageous because of label-free and kinetic studies exploring properties that are not offered by many other systems, giving direct and real-time detection of targets. SPR based assays are widely used to detect several types of cancer cells and biomarkers due to their high sensitivity . Li et ay stages . Electroy stages . A bi-fuy stages . A highly stages . Loyez ey stages .SERS spectroscopy has emerged as a promising tool for characterization in the field of nanoscience, i.e., widely investigated in cancer-related applications –62. The in situ deposition of polydopamine around exosomes particles  finds useful applications in cancer imaging . To overAn early cancer diagnosis is particularly an active research area because early detection can help to improve patient survival and disease prognosis. For this purpose, very sensitive and stable methods are needed for early cancer diagnosis . The maiSince early cancer detection has significant roles to increase available treatment options for the longer survival of patients, advances in various types of optical aptasensors for the detection of cancer cells and biomarkers or exosomes have been comprehensively summarized in this mini-review. Fluorescence-based label-free/labeled  aptasensors in combination with different nanomaterials/dyes, etc. as fluorophores, and quenchers to quench (change) the fluorescence properties as a result of specific interactions, have gained increasing attention. ECL and CL owing to their wide-ranging calibration and low background signals have recently been broadly exploited. Other types of optical aptasensors based on SPR, TCM, and SERS, etc. are also highly recommended for early-stage cancer diagnostics. Colorimetric methods combined with several different latest strategies  implicate the simplest aptasensors and can be analyzed easily with the naked eye.Several optical aptasensors reported for cancer early detection exhibit good performance in terms of selectivity and sensitivity, yet commercially available aptasensors just appear as the tips of some icebergs when we compare them to the mighty academic literature available in this area. Some new methods are still in lab trials with the early results favoring their commercial applications outside labs. However, some important technological issues and challenges still need to be addressed or improved. First, only a limited number of good specificity/sensitivity aptamers are available against a certain type of cancer cells/biomarkers, and more aptamers need to be screened that could target multiple cancer biomarkers without any complexity or off-target recognition in biological samples. Second, aptasensors need further investigations for clinical applications with real, undiluted (raw) biological samples with a primary focus on aptamer specificity, high sensitivity, cost-effectiveness, and simple operation. Overall, it is evident that the full bloom of optical aptasensor technology for cancer diagnostics is still on the way to a bright future.All authors listed have made a substantial, direct, and intellectual contribution to the work and approved it for publication.We acknowledge the financial support from “the Fundamental Research Funds for the Central Universities (No. YD2070002013)” and the National Natural Science Foundation of China (No. 31570755).The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Neuroscience has seen substantial development in non-invasive methods available for investigating the living human brain. However, these tools are limited to coarse macroscopic measures of neural activity that aggregate the diverse responses of thousands of cells. To access neural activity at the cellular and circuit level, researchers instead rely on invasive recordings in animals. Recent advances in invasive methods now permit large-scale recording and circuit-level manipulations with exquisite spatio-temporal precision. Yet, there has been limited progress in relating these microcircuit measures to complex cognition and behaviour observed in humans. Contemporary neuroscience thus faces an explanatory gap between macroscopic descriptions of the human brain and microscopic descriptions in animal models. To close the explanatory gap, we propose adopting a cross-species approach. Despite dramatic differences in the size of mammalian brains, this approach is broadly justified by preserved homology. Here, we outline a three-armed approach for effective cross-species investigation that highlights the need to translate different measures of neural activity into a common space. We discuss how a cross-species approach has the potential to transform basic neuroscience while also benefiting neuropsychiatric drug development where clinical translation has, to date, seen minimal success.This article is part of the theme issue ‘Key relationships between non-invasive functional neuroimaging and the underlying neuronal activity’. In humans, this venture is limited by the non-invasive tools and techniques currently available. Magnetic resonance imaging (MRI) and magnetoencephalography (MEG), for example, are restricted to coarse measures of neural activity that aggregate the diverse responses of thousands of neurons over space and time. These tools provide macroscopic measures of cognitive processing that relate to human behaviour but fail to provide insight into neural activity at the microcircuit, cellular and synaptic levels. To investigate neural activity at the microscopic level, to reveal the division of labour across cell types in their host circuit and assess causality, we instead rely on invasive procedures in animal models. In recent years, we have seen the development of new recording techniques that can simultaneously monitor activity from thousands of cells across numerous brain regions. Furthermore, the expansion in the use of genetic tools in rodents now permits manipulation of neural activity at unprecedented spatio-temporal resolution. Yet, in contrast with research carried out in humans, these approaches rarely characterize activity at the macroscopic level and interpreting animal behaviour is challenging. This makes it difficult to establish how neural mechanisms recorded and manipulated in animal models relate to higher-order cognition.Owing to the distinct training requirements for neuroscientists conducting research in humans or animal models, laboratories typically employ a species-specific approach where research is focused on only one species. By and large, this centres research on either the macroscopic or microscopic level, leaving an explanatory gap between genetic, (sub)cellular and circuit-level mechanisms on the one hand, and higher-order cognition on the other. The adverse implications of this explanatory gap are made evident by high failure rates observed in clinical trials, where neuropsychiatric drugs have one of the highest failure rates at Phase III . With anHere, we explore the view that investing in an interdisciplinary, cross-species approach will provide a means to integrate different levels of neuroscientific description, paving the way for a comprehensive understanding of how the mammalian brain serves adaptive behaviour. We outline a three-armed approach for effective cross-species investigation. First, to provide appropriate interpretation of non-invasive methods, different tools (i.e. both non-invasive and invasive methods) need to be employed within the same species. Second, to provide a direct means to relate signals recorded across different species, the same tools need to be employed across multiple species. Third, to obtain complementary datasets that take advantage of the best tools available in each species, different tools should be employed across different species using a comparative approach. Thus, by complementing current approaches that provide detailed descriptions of neural processing within one species, or even within one brain region, a cross-species approach may uncover a set of general principles that describe the neural basis of cognition and behaviour in terms of cellular and circuit-level mechanisms. Moreover, adopting a cross-species approach may harness the translational value of fundamental neuroscience to develop effective neuropsychiatric treatment.2.Each tool used for measuring neural activity has its own advantages and limitations. Of the non-invasive techniques available for measuring brain activity, electroencephalogram (EEG), MEG and functional MRI (fMRI) all provide readouts of activity at the macroscopic level.The temporal resolution of EEG and MEG out-performs that of fMRI, and while EEG has poor spatial resolution, MEG can match the spatial resolution of fMRI in cortical brain regions. MEG uses highly sensitive magnetometers to measure the weak magnetic fields generated by electrical activity of neuronal populations within the brain . The recConventional MEG uses superconducting quantum interference devices (SQUID). However, these sensors require cryogenic cooling together with thermal insulation, which limits the proximity between the SQUID and the subject's scalp. Recent developments have introduced new scalp-mounted devices that operate at room temperature using optically pumped magnetometers (OPMs) –12. ThesfMRI, on the other hand, is more widely available than MEG and provides a means to image the entire brain at relatively high spatial resolution. fMRI has the advantage of being readily compared with other imaging modalities that provide insight into brain anatomy, connectivity and chemical composition, or combined with causal interventions such as non-invasive brain stimulation. However, its interpretation is not straightforward: the blood oxygen level dependent (BOLD) signal measured using fMRI provides only an indirect measure of neural activity and the relationship between neural activity and the BOLD signal is complex ,15. RemaWhile fMRI boasts the highest spatial resolution of available non-invasive methods, even submillimetre ultra-high-field fMRI includes tens of thousands of neurons per voxel. Researchers have, therefore, developed methodological approaches to map the coarse spatial organization of neurons. For example, fMRI can be used to measure retinotopic –25, tonoin vivo at a resolution previously restricted to invasive methods in animals [The improved spatial resolution afforded by an increase in signal-to-noise ratio at high-field strength has further opened up the possibility for columnar fMRI ,35 and l animals –50, lami animals ,51. ReliAlongside improvements in spatial resolution, recent advances in fast scanning techniques have pushed the temporal resolution of fMRI. These include multiband and simultaneous multi-slice sequences that achieve subsecond sampling –54. The To measure neural events at a subsecond resolution requires alternative analytical approaches. Recent fMRI investigations demonstrate that relatively rapid neural sequences (on the order of a few hundred milliseconds) may be decoded using multivariate decoding techniques that assess subtle differences in the activity patterns across voxels, measured across consecutive repetition times (TRs) . Simulatin vivo non-invasive recordings of the human brain will at best provide an index or indirect measure for activity at the subvoxel resolution, as demonstrated by innovative approaches showing insight into neural codes [But despite these improvements in spatio-temporal resolution and analytical approaches, fMRI and other non-invasive methods, such as MEG, continue to provide only limited insight into cellular and synaptic processes that characterize neural activity at the microcircuit level. Therefore, while ongoing research is continuing to deepen our understanding of the relationship between specific neuronal subtypes and different vascular variables that affect the BOLD signal –71, certal codes , temporaal codes –62, synaal codes ,73,74 anal codes . The val3.Except in unusual circumstances, such as during electrocorticographic and depth recordings in epilepsy and deep brain stimulation patients ,78, ethiin vivo electrophysiology that has temporal resolution sufficient to resolve individual action potentials, the fundamental currency of neural information. The micro-machined silicon probes developed in recent years, such as neuropixels [Invasive methods available for recording neural activity during behaviour include ropixels , can be ropixels , thus reropixels . When coropixels ,83 and sropixels . Furtherropixels ,86.Drosophila [While distinct cell types, including excitatory and inhibitory neurons, may be deduced from electrophysiological features, complementary methods must typically be employed to cross-validate identified neuronal types –91. Notaosophila , geneticosophila . While sosophila .Particularly in small animals, genetic tools further support causal manipulations, such as optogenetics where light is used to control neural activity with cell-type and millisecond precision ,102. Thein vivo reconstructions and visualization of the three-dimensional architecture of white matter tracts, they do not trace axons directly, and variables such as crossing fibres and fibre geometry, among others, influence the accuracy of the results. Therefore, results need to be carefully interpreted and often validated in animal models when possible.These readouts and manipulations of microcircuit-level activity go hand-in-hand with an understanding of structural neuroanatomy where axonal tracing in animal models still provides what is often termed the ‘gold-standard’. Such invasive tools are currently the only methods available for identifying the direction of a connection and the presence of synapses. While non-invasive anatomical methods, such as diffusion-weighted MRI-based tractography, have the advantage of providing Invasive methods in animal models are, however, not without their own limitations. Hubel & Wiesel , who pioin vivo imaging during ongoing behaviour. Optogenetic stimulation risks driving neuronal responses outside their typical physiological range, causing bulk activation and the potential for unnatural plasticity; and the resulting behavioural effects may reflect the function of a manipulated circuit, as opposed to a loss- or gain-of-function manipulation.The rapidly expanding use of optical and genetic tools available in rodents has also been met by growing recognition of the pros and cons associated with these methods. For instance, the slow kinetics of calcium imaging complicate interpretation of the signal , and volHowever, perhaps the most pressing concern is simply that these contemporary invasive tools are predominantly employed in rodents. Rodents are used as model organisms that allow comprehensive measurement and manipulation, but research is restricted to the repertoire of rodent behaviours that are easy to interpret. This may in part be overcome by improved characterization and quantification of ethological rodent behaviour using more precise and automated tools ,106. How4.Having examined current state-of-the-art tools available for investigating neural activity in both humans and animals, the explanatory gap between non-invasive and invasive tools is evident and highlights the limitation of a species-specific approach. On the one hand, non-invasive methods available in humans can relate measures of macroscopic activity to complex cognition and behaviour. Yet, these non-invasive techniques are limited by poor spatial or temporal resolution, and, at least for fMRI, they provide an indirect measure of neural activity. On the other hand, invasive methods available in animal models can measure neural activity and synaptic changes at high spatio-temporal resolution, but often limit investigation to a single neural circuit or brain region and behaviours that are easy to interpret. Microscopic measures in animal models therefore fall short of providing insight into distributed computations that underlie the diverse and complex repertoire of human behaviour.Can we use a cross-species approach to bridge the macroscopic–microscopic divide? After all, different species have different lifestyles, occupy and adapt to different ecological niches, and are exposed to different evolutionary pressures. While these different evolutionary pressures may in part account for differences between species ,108, oveAt the structural level, early work by Brodmann  and otheSimilarly at a functional level, resting-state fMRI in primates reveals a remarkably conserved profile for functional connectivity across large-scale networks such as the default mode network  can reveal structural and functional specialization . Thus, a(a)Approach 1 will establish a deeper understanding of the relationship between the BOLD signal and the underlying neural activity. Since the relative merit of this approach and interpretation of the BOLD signal have been detailed elsewhere [Approach 1 in passing.Different tools need to be simultaneously employed within the same species to provide appropriate interpretation of non-invasive methods. With regard to fMRI, the relationship between the BOLD signal and neural activity can be characterized in animal models by simultaneous fMRI and electrophysiological recordings –144, or lsewhere ,146, in (b)The same tools need to be employed across multiple species, to allow direct comparisons to be drawn between different species. For example, to reveal functional properties that generalize across species, MRI may be used to perform comparative investigations (see §6). Alternatively, electrophysiology may be employed across different animal models and compared with pre-operative recordings in epilepsy patients. Functional comparisons can be established by matching behavioural assays (see §7).(c)The third approach takes advantage of behavioural assays that can be implemented across species but uses the best tools available in each species to characterize the macroscopic and microscopic levels in tandem. To compare complementary datasets, this approach requires quantitative analytical approaches that translate different measures of neural activity into a common space . In this manner, data obtained from different recording modalities can be directly compared. This third approach can thus facilitate an interplay between human and animal research that goes beyond the sum of its parts.6.Approach 2). Cross-species MRI seeks to do exactly this, using non-invasive MRI to quantify neural structure and function in vivo across both animals and humans. First, comparable signals can be obtained across species, providing a means to assess structural and functional homology while also identifying brain regions and connections unique to a particular species [The same tools need to be employed across multiple species . Yet, recent developments in cryo-coils , optimizSmall-animal MRI is predominantly carried out in anaesthetized or sedated animals, primarily owing to the requirement to hold the head in the same position during imaging. This makes small-animal MRI highly suitable for studies investigating structural changes throughout development and ageing and in response to interventions . Long-laUnder anaesthesia, small-animal fMRI has been acquired during stimulus-evoked paradigms to successfully map layer-specific BOLD activation , whole-bApproach 1). For example, multi-modal imaging can reveal linear fits between neuronal and capillary responses (two photon microscopy) and mesoscopic responses detected with BOLD fMRI, demonstrating that even low levels of neuronal activation can trigger elevations in blood flow [Moving beyond tools that facilitate direct comparison between animals and humans, small-animal imaging has seen recent advances in multi-modal imaging where fMRI is combined with invasive neurophysiological measures . This necessitates cross-species comparison across different recording modalities using a common unit measure for neural activity.To integrate micro- and macroscopic levels of description, we must also take advantage of state-of-the-art tools available in different species . Therefore, for each pair of experimental conditions, the similarity in the response pattern elicited by the two conditions is assessed using a correlation or distance metric ,209. TheRSA has been successfully used to compare neural responses to visual objects in humans and non-human primates. Using fMRI and electrophysiological recordings, respectively, highly comparable representational structure can be observed in human and macaque inferotemporal cortex (area IT)  figure . SimilarApproach 1).While this convergence between electrophysiology in animal models and multivariate human fMRI is encouraging, we must bear in mind the limitations of both fMRI and electrophysiology. As discussed above, for fMRI, the relationship between neural activity and the BOLD signal measured from a given voxel is non-trivial. For electrophysiology, only a biased subsample of neuronal responses are monitored and RSA overlooks information in the precise timing of spikes. The limitation of these recording modalities and differences in methodological sensitivity to representational information may give rise to differences in RSA or other multivariate methods employed across species. For example, multivariate pattern analysis applied to both fMRI and electrophysiology data from the macaque reveals that fMRI multivariate pattern analysis is insensitive to some representational information that can otherwise be decoded from single-unit recordings . The accIdentifying spatial homologies between species as distant as the mouse and human presents a further challenge. The classic method of mapping like to like in anatomical ontologies, i.e. the mouse hippocampus is equal to the human hippocampus, remains the most employed method. Yet, it is likely that homologies between rodent and human will not be best captured by this type of one-to-one mapping. Instead, it is plausible that, over the course of evolution, functions that are highly localized in one species might be more distributed in another. Using additional information, such as the expression patterns of homologous genes or connectivity mapped via resting-state fMRI or diffusion MRI , could a9.Approaches 2 and 3). By mathematically formalizing the complex interactions inherent to the brain, computational models can extract common quantitative descriptions for neural activity at both micro- and macroscopic levels. The resulting models may further be used to simulate and predict the effect of biophysical activity at both a cellular and systems level.In addition to analytical tools (see §8), computational models may be used to bridge the explanatory gap between neural recordings in humans and animal models  modelling, where physiological and biochemical differences between species are used to translate mechanistic knowledge from one species into another –232. The10.Non-invasive measures of human brain activity are not routinely used as a tool for diagnosis, despite being readily available. As discussed above, this may be attributed to the explanatory gap between macroscopic measures of neural activity acquired using tools such as fMRI, and microcircuit mechanisms recorded in animal models.Across medicine, this is perhaps most evident in modern psychiatry . DiagnosEven in cases where there is a single gene disorder, promising results in animal models have at times failed to translate into drug development. A good example is the recent mGluR5 trials in Fragile X Syndrome. This high failure rate may in part be attributed to poor methodology. For example, animal studies appear to overestimate the likelihood of a treatment being effective, simply because negative results are often unpublished . For disIn the current socioeconomic climate, the cost of developing new neuropsychiatric drugs and neurotechnologies is rising, and as a result, pharmaceutical companies will move away from neuroscience to shift resources to more profitable areas. By developing a cross-species approach within fundamental neuroscience, we propose a means to build a foundation from which to bridge the explanatory gap between a behavioural characterization of neuropsychiatric disease and the underlying pathophysiology. This may be achieved by developing sensitive and effective tools for cross-species basic research that include imaging, behavioural assays, analytical methods and computational models, as outlined above.11.Neuroscience has seen substantial development of non-invasive methods available for investigating the living human brain. Yet, owing to ethical and practical difficulties, these methods rarely permit insight into microcircuit-level mechanisms. To access the microcircuit, researchers instead rely on invasive recordings in animals, where recent advances in genetic tools now permit circuit-level manipulations with exquisite spatio-temporal precision. However, owing to challenges associated with animal research, there has been limited progress in understanding how neural circuits interact or relate to complex behaviour. Contemporary neuroscience thus faces an explanatory gap between macroscopic descriptions of cognition and behaviour in humans, and microscopic descriptions of cellular and synaptic processes in animal models. To close this explanatory gap and establish a more holistic description of brain function, here we call for an integrative cross-species approach. This approach is broadly justified by evidence showing preserved homology of neural circuits across mammals.To embark on effective cross-species investigation, first we highlight the need to establish a deeper understanding of the relationship between non-invasive methods, such as the BOLD signal, and underlying neural activity. This may be achieved by employing multiple different tools within the same species. Second, to promote comparative investigation across species, we need to employ the same tools across multiple species. Cross-species MRI provides a unique opportunity to achieve this, by obtaining non-invasive markers of neural activity in both humans and animals that can be directly related to invasive manipulations in animals. When combined with cross-species behavioural assays, as exemplified by studies using VR, this comparative approach has the potential to reveal non-invasive markers of microcircuit mechanisms. Third, by taking advantage of the best tools available in each species, cross-species analyses and computational modelling may provide a means to translate measures of neural activity into a common space, despite differences in species and recording modality. Together, these three approaches may bridge the explanatory gap between macroscopic and microscopic descriptions of neural activity in the living human brain. In the context of clinical translation, where we have seen minimal success in neuropsychiatric drug development, a cross-species approach has the potential to reveal pathophysiology mechanisms responsible for neuropsychiatric disease.


A cyst is a closed sac-like structure in which cyst walls wrap certain contents typically including air, fluid, lipid, mucous, or keratin. Cyst cells can retain multipotency to regenerate complex tissue architectures, or to differentiate. Cysts can form in and outside the skin due to genetic problems, errors in embryonic development, cellular defects, chronic inflammation, infections, blockages of ducts, parasites, and injuries. Multiple types of skin cysts have been identified with different cellular origins, with a common structure including the outside cyst wall engulfs differentiated suprabasal layers and keratins. The skin cyst is usually used as a sign in pathological diagnosis. Large or surfaced skin cysts affect patients’ appearance and may cause the dysfunction or accompanying diseases of adjacent tissues. Skin cysts form as a result of the degradation of skin epithelium and appendages, retaining certain characteristics of multipotency. Surprisingly, recent organoid cultures show the formation of cyst configuration as a transient state toward more morphogenetic possibility. These results suggest, if we can learn more about the molecular circuits controlling upstream and downstream cellular events in cyst formation, we may be able to engineer stem cell cultures toward the phenotypes we wish to achieve. For pathological conditions in patients, we speculate it may also be possible to guide the cyst to differentiate or de-differentiate to generate structures more akin to normal architecture and compatible with skin homeostasis. Skin is the largest organ of the body in mammal. Along with the appendages, skin functions on regulating body temperature, defending against micro-organisms infection, and protecting the body from external harmful matters such as toxic substances and UV irradiation . Skin isA skin cyst includes a basal epidermal layer surrounded by layers of dermal cells. The basal layer differentiates toward the inside of the cyst into the suprabasal layers which undergo terminal differentiation to produce keratin debris . Skin cyCyst formation is required in the early stage of embryogenesis and functional maintenances of organs. A blastocyst is a physical structure developed in the early development of mammals. A blastocyst contains the inner cell mass which subsequently develops the embryo and the outer layer which forms blastocele. An ovarian follicle, a spheroid cellular aggregation set, can influence stages of the menstrual cycle by secreting hormones. In every menstrual cycle, each ovarian follicle has the potential to release an egg cell for fertilization. Additionally, in adult tissues such as the thyroid gland, thyroid follicle consists of cuboidal epithelium and contents which contain colloid, thyroglobulin, and iodine. Thyroid follicles secret thyroid hormones to regulate body metabolism and growth.Cysts can be observed in almost every organ such as skin, kidney, liver, ovary, lung, joint and mammary gland, ranging from microscopic scale to several centimeters in diameter. For example, renal cysts with fluid-filled contents can be observed in a single cyst and several polycystic kidney diseases . ProgresSkin cysts can form due to mistakes during skin development. For example, variants in PLCD1 are detected in families with multiple trichilemmal cysts . DermoidSkin is constantly subjected to insults such as UV radiation, toxin, invasive pathogens, etc . In respThe inflammatory response to the grafted epidermal tissues during implantation can be important in the formation of skin cysts. To protect tissues from stimuli such as pathogens infection or damage in cells, inflammatory responses involving immune cells, blood vessels, and molecular mediators are mobilized to eliminate the necrotic cells and tissues to facilitate tissue repair . Thus, aCell-cell adhesion is the basis for forming tissue integrity. Conditional knockout of Desmocollin3 (Dsc3) in the skin epithelium destroys the cell-cell adhesion, causing intra-epidermal blistering, and cyst formation in the hair follicle . AnotherA hair follicle is a complex micro-organ with multiple cellular components including the bulge, ORS, inner root sheath (IRS), hair bulb, and dermal papilla. Homeostasis of the hair follicle is maintained by the coordination of extracellular matrix signaling, autocrine signaling, paracrine signaling, systematic signaling, etc . AbnormaBmpr1a knockout and activation mice (Sonic Hedgehog (Shh), Transforming Growth Factors β (TGFβ), and Bone Morphogenetic Protein (BMP) signaling pathways are required in hair follicle morphogenesis and hair follicular growth . Specifiion mice .Wnt/β-catenin signaling largely influences hair follicle stem cells (HFSCs) behaviors including activating HFSCs during regeneration and promoting their differentiation during hair growth , 2014. DJagged 1, Notch1, Notch2, or RBP-Jκ in skin epithelia blocks the differentiation of IRS, induces the differentiation of ORS cells besides HFSCs, and causes the skin cyst formation , hairless-rhino (hrhrrh), rhino (hr Vhhrrh), bald Mill Hill (hrrhbm) , VitaminMapping the molecular mechanisms by which these signaling pathways interact with each other to control the hair follicle homeostasis or skin cyst formation requires further bioinformatics approaches and functional tests. At least known studies have revealed that Wnt and Notch pathways are largely involved in this molecular regulatory network .in vivo and in vitro. Growing evidence shows that the cyst structure retains certain multipotency to self-renew and differentiate, and de novo regenerate mini-organs resembling those formed during the developmental processes. Cyst forms budded structure during intestinal organoid development, with involvement of fate-specific changes in osmatic and actomyosin forces, as well as Yap signaling pathway activation (in vivo and in vitro.Recent studies on organoid formation demonstrate that the cyst formation is a common and essential process to generate the mini-organs . Most ortivation . This enTissue-engineered skin represents a useful strategy for the treatment of skin injuries. Primary cultured skin cells, iPS-differentiated skin cells, embryonic stem cells-differentiated skin cells, etc., are used to generate fully functional skin with appendages formation. Accompanying with fully functional skin formation during the explant transplantation into the nude mice is the formation of skin cysts, which express the epidermal stem cell markers. Appendages such as hair follicles not only form from the regenerated skin but also the skin cysts .in vitro, which is termed skin organoid culture (in vitro cultured organoids can form the fully functional skin with epidermis and dermis structures, as well as with regeneration of skin appendages such as hair follicle (in vitro is required for further tissue regeneration. The reason why cells prefer to choose this more complex way to form fully functional skin requires further investigation. However, one possibility is that the easiest way for one to reach the destination from the beginning may not be through a straight line but by consuming their lowest energy. Thus, the skin cells may use the same strategy to form fully functional skin by forming the skin cyst to maintain their multipotency. Indeed, adult cells with declined regenerative ability can be reactivated to form skin organoid through cyst formation by applying certain factors during culture and regenerate hair follicles upon regeneration (Skin cyst formation also occurs when pluripotent stem cells are cultured  culture , 2020. Tfollicle , sebaceofollicle  and sweafollicle . This inneration .Here we show cyst form from the progenitor/stem cells who find their route to maintain multipotency and can regenerate the original tissues under pathological and skin organoid culture conditions. Cysts in pathological conditions are formed from complex tissue architectures by making closed sac-like tissue structures that contain simple or complex tissues depending on their origin and mutation type, with complex molecular regulatory networks largely involving Wnt and Notch pathways. They also tend to form during renewal conditions such as hair cycling. They failed to form complex structures and get “stuck” in the cyst stage. Organoids first form cysts with relatively homogeneous progenitors and tissue structures, and then start developing more complex tissue architectures with cell differentiation and tissue patterning, with the involvement of extracellular matrix and protein kinases C and R . These lHowever, several outstanding questions regarding skin cyst formation remain. For example, how to guide cyst in organoid cultures to continue morphogenesis? This can be achieved by modifying the molecular profiles of the cyst cells. The configuration may also be changed by 2-dimensional or 3-dimensional culture conditions. Activation or de-stabilization of the cyst can also be achieved by altering the physical properties of the surrounding environment, by affecting the affinity of ECM and cyst epithelial cells. What happens when the cyst configuration de-stabilization? Is it the loss of apical-basal cell polarity? Realignment of cell adhesion and neighboring cellular partners? Does the rigid structure enter a more fluid state similar to those observed in epithelial-mesenchymal transition?With the organoid cultures as a platform to investigate the mechanism by which skin organoids undergo a morpho-space development, from aggregate to skin cyst, then to a planar skin with hair regeneration will help answer these questions. As researches on the topic of skin biology continue, understanding the control of cyst configuration, we hope to provide a theoretical basis for understanding the pathogenesis of skin cysts, improving the therapeutic methods of skin cysts, and producing more functional skin organoids for tissue regeneration.The original contributions presented in the study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding author/s.C-MC and ML contributed to the conception and design of the manuscript. WQ, P-RG, C-MC, and ML wrote the article and approved the final version. All authors read and approved the final manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


The implications of various forms of hypoxia to physiological or pathological conditions are enormous. In this manuscripts' collection of “Research Topics,” expert authors focused on the effects of intermittent hypoxia (IH), the hallmark of obstructive sleep apnea (OSA) on physiological and pathophysiological conditions and potential treatments, each, contributing original research articles and reviews in their field.OSA is a major health risk-factor, depicting increased mortality rates. This is attributed to its high occurrence and association with various co-morbidities, including cardiovascular, cerebrovascular, metabolic, and increased cancer risk. Thus, research has been aimed at identifying the underlying mechanisms for these associations. Two of the most fundamental mechanisms, oxidative stress and inflammation were shown to be affected by IH. Yet, different severity-dependent changes in frequency, magnitude, and chronicity, considerably alter the patterns of IH, and thereby initiate diverse and sometimes opposing outcomes, altering physiological measures, multiple signaling pathways, and genetic-epigenetic expression.in-vitro studies, showed beneficial rather than detrimental effects, suggesting that some IH patterns may induce protective mechanisms to tissues and organs and particularly the heart, rather than damage. The involvement of oxidative stress through reactive oxygen species (ROS)-dependent signaling pathways is implicated both in IH and in OSA. Thus, while some patterns of IH are detrimental, others could confer protection  treatment reduced night-time but not daytime blood pressure.Evidence linking OSA with essential hypertension has been reported ever since OSA has been scientifically investigated. Gabryelska et al. reviewed the involvement of platelets in the development of cardiovascular morbidity in OSA. Blood platelets play a central role in homeostasis and thrombosis. As such, their activation and function considerably contribute to cardiovascular morbidity. Although the studies focusing on platelet function in OSA and IH are limited, this review is comprehensive and systematic. Increased mean platelet volume (MPV), indicative of cardiovascular morbidity, was associated with OSA severity. The efficacy of CPAP treatment in decreasing platelet-dependent cardiovascular risk, based on platelet activation markers, is summarized, while anti-platelet treatments combined with CPAP are suggested as potential therapeutic targets to decrease cardiovascular risk in OSA.Several papers highlighted mechanisms involved with cardiovascular complications in OSA. Avezov et al.. Endothelial Cell-Colony Forming Units (EC-CFUs) and their angiogenic paracrine properties were shown to closely correlate with vascular functions and retain measures of vascular health . Treatment with antioxidants and ROS inhibitors decreased or abolished EC-CFUs numbers and angiogenic measures, emphasizing the crucial role of ROS in mediating vascular health, possibly by activating vascular adaptive-protective mechanisms.The significance of IH-dependent ROS production to vascular health was investigated by r health . Patientr health . SimilarKhalyfa et al. investigated the beneficial effects of celecoxib  and losartan  on IH-induced vascular dysfunction. The cardiovascular protective impact of LOS and CEL was mediated by their direct effects on endothelial cells, rather than modulating exosomal cargo.The association between IH and cardiovascular disorders consequent to increased endothelial dysfunction was investigated in healthy subsects exposed to IH, using exosomal release in plasma and its potential control by drugs. Exosomes may act as vehicles for propagating damage to endothelial cells, while drug interventions may provide protection for the endothelium. Almendros et al. to investigate hypoxia inducible factor (HIF)-1α and VEGF expression in cutaneous melanoma (CM) patients with OSA. Recent epidemiological studies show an association between OSA and poorer solid malignant tumor outcomes. Relying on a large multicenter cohort of patients diagnosed with CM and SDB, they investigated putative pathways to explain these associations. HIF-1α and VEGF were determined in CM tumoral lesions. HIF-1α was independently associated with SDB severity. These findings shed a new light on the epidemiological association between cancer and OSA, whereby OSA may play a deleterious role in cancer outcomes. It has yet to be defined which types of cancers are more prone to express poorer outcomes in OSA.A mechanistic approach was undertaken by Menal et al. investigated whether IH altered brain cortex tissue stiffness in early-onset AD mutant mice exposed to IH mimicking OSA. Chronic IH did not modify the stiffness of brain cortex in normal mice, and similarly did not alter the mechanical properties of the cortex in this murine AD model. AD mutant mice exhibited reduced brain tissue stiffness following both normoxia and IH, likely due to increased edema and demyelination in AD.Alzheimer's disease (AD) is another pathology associated with OSA. Evidence from patients and animal models suggests that OSA may increase the risk of AD and that AD is associated with reduced brain tissue stiffness. Collectively, the pathologies described herein are associated with OSA and IH. However, importantly, the IH in OSA is implicated in eliciting both detrimental and protective mechanisms in cardiovascular morbidity.The author confirms being the sole contributor of this work and has approved it for publication.The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Humans and animals live in social relationships shaped by actions of approach and avoidance. Both are crucial for normal physical and mental development, survival, and well-being. Active withdrawal from social interaction is often induced by the perception of threat or unpleasant social experience and relies on adaptive mechanisms within neuronal networks associated with social behavior. In case of confrontation with overly strong or persistent stressors and/or dispositions of the affected individual, maladaptive processes in the neuronal circuitries and its associated transmitters and modulators lead to pathological social avoidance. This review focuses on active, fear-driven social avoidance, affected circuits within the mesocorticolimbic system and associated regions and a selection of molecular modulators that promise translational potential. A comprehensive review of human research in this field is followed by a reflection on animal studies that offer a broader and often more detailed range of analytical methodologies. Finally, we take a critical look at challenges that could be addressed in future translational research on fear-driven social avoidance. From an evolutionary perspective, the social environment is not only crucial for survival and reproductive success but substantially shapes physical and mental health . Under cSocial avoidance is a physiological and sometimes even life-saving facet of human behavior that is accompanied by aversive emotions and thoughts upon expecting or experiencing social situations. It can therefore function as a safety behavior that prevents or alleviates feelings of shame and anxiety . In expeTo investigate the interference of socially evaluative stress with approach-avoidance, the Trier Social Stress Test (TSST), a laboratory stress experiment usually performed outside the fMRI scanner, is used in combination with other tasks such as the AAT to create a naturalistic, stressful and socially-threatening situation , 10. TheThere have been various experimental attempts to quantify the magnitude of social avoidance. One such study was performed by Schultz et al. . SpecifiOther methods established to examine social avoidance in humans include go/no-go and social incentive delay tasks, often operationalized by implementing social or monetary rewards and the avoidance of punishment –20. HaraConsistent with the premise that social avoidance is characterized by a fear-driven propensity to reduce feelings of anxiety and shame in social contexts , the amySince the amygdala and NAc both possess important roles in the neural processing of social avoidance, functional connectivity between the two may be relevant. Indeed, during decisions whether or not to engage in social interactions, higher levels of anxiety were found to be associated with increased functional connectivity between the right NAc and the amygdala, accompanied by decreased functional connectivity between the right NAc and the perigenual anterior cingulate cortex (pACC) . Chang aOverall, the evidence largely confirms the vigilance-avoidance hypothesis, which describes an enhanced vigilance towards social threat in socially anxious subjects, followed by avoidance behavior . High-avIf its intensity and/or frequency exceeds a certain level, social avoidance develops into pathological forms that can lead to complete social isolation, inability to work, and significant suffering. Social avoidance ranges on a stepless spectrum from functional-adaptive to inflexible-maladaptive. In principle, two forms of pathological social avoidance can be discriminated against, namely social anxiety with and without paranoid symptoms. The latter are mainly characterized by a biased perception of reality (attribution bias), that leads to irrational mistrust and suspicion of others and thus often also to hostile beliefs and rejection hypersensitivity .Pathological social avoidance can occur, at least transiently, in almost any psychiatric disorder except acute mania and is, furthermore, the main characteristic of a social anxiety disorder (SAD) which is also called social phobia, e.g. in the ICD-10 diagnosis catalog. Besides SAD, social anxiety occurs very frequently in patients with an avoidant personality disorder. SAD is one of the most frequent mental illnesses  with an Criteria of psychiatric diagnoses such as SAD can be assessed in clinical expert interviews and by validated diagnosis-specific and/or transdiagnostic inventories. The widely used Structured Clinical Interview for DSM (SCID) has been proven to detect SAD with reasonably high specificity and sensitivity , 54. IntPsychiatric disorders are generally highly comorbid with each other. It is well accepted that SAD is more frequent in female than in male subjects , 58. SomSocial evaluative concerns are the most common type of paranoid thoughts . ParanoiAvoidance is a behavioral manifestation of fear and anxiety that tends to generalize particularly in individuals with an elevated vulnerability for mental disorders. PTSD patients avoid trauma-related cues, GAD patients avoid a constantly increasing amount of everyday risks, and phobic patients the object of phobia such as social situations in the case of SAD. Accordingly, cognitive-behavioral treatments (CBT) targeting pathological avoidance by gradual exposure to stimulating cues are effectively used in the treatment of SAD and other anxiety disorders , 63. PatThe high comorbidity of psychiatric disorders points at the imprecision of their definitions that calls for a novel biology-informed taxonomy. Accordingly, meta-analyses have shown that genetic alterations as well as changes in brain structure and function in psychiatry are often non-specific with similar or even identical changes appearing in distinct mental disorders —the sameCortisol is the major effector hormone of the hypothalamic–pituitary–adrenal (HPA) axis, which, together with the sympathetic nervous system (SNS) forms the two main stress hormone systems in humans. Since both systems are essential for stress coping, they belong to the most studied biological systems in clinical psychiatry. Studies indicate augmented processing of social threat after cortisol administration, which may be specific to high-avoidant and high-anxious participants , 79. FurSocial approach-avoidance actions are influenced by different modulators of mood and behavior. For instance, single-dose administration of testosterone promotes an increased approach to social threat, accompanied by decreased social avoidance, in healthy controls , 84 as wA neuropeptide hormone, whose anxiolytic , 93 and While oxytocin-induced approach behavior in female subjects, at least in positive social contexts , pair-boOxytocin and testosterone both interact with the monoaminergic neurotransmitter systems including the dopaminergic pathways , which mExcessive stress-induced signaling of glucocorticoid hormones such as cortisol inhibits BDNF synthesis and thereby reduces neural plasticity. The upregulation of BDNF through pharmacotherapy may reverse brain atrophy and thereby contribute to the antidepressant effect in stress-related disorders . The BDNThe endocannabinoid system (ECS) is a widely expressed neuromodulatory system involved in the regulation of various physiological and pathological processes. It is comprised of cannabinoid receptors CB1 and CB2, their endogenous ligands (endocannabinoids), and enzymes involved in endocannabinoid metabolism . In the In sum, it is the complex interplay of various modulators that influences social avoidance and guides behavior. Further research, especially in clinical populations, is mandatory. An overview of the aforementioned modulators and their influence on social approach-avoidance behavior is shown in Table Defining normal social behavior in animals, including its affiliative and aversive poles, depends on multiple factors like species, sex, age, and the environment they live in . Social behavior comprises and requires approach and avoidance, interaction, recognition, and formation of memories and can be driven by social reward or fear. In rodents and other gregarious species, fear of new social interaction partners is usually overcome by the physiological drive to socially approach and interact. These opposing processes are regulated via different brain circuitries and neurotransmitters and -modulators , 156. WeSocial avoidance in animals is evoked by social adversity or threats, such as social isolation or instability, maternal separation or abuse, social fear conditioning, subordination, and social defeat . SystemiThe circuitry determining social behavior involves the anterior and ventromedial hypothalamus, amygdala (AMY), the bed nucleus of the stria terminalis (BNST), lateral septum, periaqueductal gray (PAG) among others. It connects with the dopaminergic mesocorticolimbic motivation and reward network , nucleus accumbens (NAc), and prefrontal cortex (PFC)) , 165.Ih) was detected in the VTA of avoidant mice after social defeat stress [Ih currents by a single infusion of the antiepileptic drug and mood stabilizer lamotrigine similarly enhanced social avoidance [Ihcurrents observed in non-avoidant mice and resulted in neuronal hypoexcitability in the VTA. Inline, local induction of hypoexcitability in the VTA by either genetic upregulating of potassium channels [Ih current via infusion of lamotrigine for 5 days [The VTA serves as a dopaminergic hub modulating activity in the NAc and the medial prefrontal cortex (mPFC) and neuronal activity patterns in the VTA correlate with social interaction and avoidance –168. Neut stress , 170 andvoidance . Converschannels  or pharmr 5 days  restoredr 5 days , 173. Thr 5 days , 173 or r 5 days . Moreover 5 days . Together 5 days . Together 5 days .Within the circuitry of VTA, NAc and mPFC, activation of projections from the infralimbic part of the PFC to the NAc reversed social avoidance in mice . In lineThe PFC is directly connected to other brain regions controlling anxiety and fear responses and dysfunction of these networks reflect a pathophysiological mechanism underlying social avoidance. Disrupted feedback control between PFC, AMY and VTA is suggested as an important cause for CSDS-induced avoidance in mice , 186. InVolumetric magnetic resonance imaging (MRI) studies in rodents also tried to detect specific anatomic alterations in avoidant phenotypes. In a post hoc analysis, the size of the hypothalamus was increased, while that of the bed nucleus of stria terminals (BNST), component of the extended amygdala , and dorNeuronal networks adapt at different time scales to changing tasks by modulating synaptic connections, often referred to as synaptic plasticity. It describes the ability of existing synapses to strengthen or weaken over time and functionally, these plastic changes are mediated by altering the number of neurotransmitter receptors at the post-synaptic site or the pre-synaptic release of neurotransmitters. The hippocampus is probably the best-studied brain region in synaptic plasticity, but its adaptions regarding social avoidance are less clear. Recently, it was demonstrated that CSDS animals with a socially avoidant phenotype show no hippocampal long-term potentiation (LTP) . UnfortuUnder healthy conditions, a well-concerted oscillation of circulating glucocorticoid hormones is maintained by the HPA axis in both animals and humans. The hypothalamus stimulates the pituitary gland with corticotropin-releasing hormone/factor , thereby sending adrenocorticotropic hormone (ACTH) to the peripheral adrenal cortex, which in turn secretes cortisol in humans and corticosterone (CORT) in rodents into the bloodstream. These glucocorticoids exert their effects via the glucocorticoid receptor (GR), which is widely distributed in the brain and most other peripheral tissues , 208. ThDysregulation of the HPA axis is not only found in impaired adult social responses but also at juvenile life stages in animals as well as in socially anxious children and adolescents . SeveralCirculating corticosterone levels have been studied repeatedly in various social stress models but mostly in chronic social defeat variations that induce social avoidance. In general, the elevation of blood corticosterone is found both in socially avoidant and non-avoidant mice directly after classic CSDS and thus is unlikely the direct cause of the disrupted social interaction  but rathMost animal research regarding social behavior is traditionally performed in males, neglecting the relevance of sex differences . In mostData on testosterone in avoidance behavior of males is not clear-cut: Lowered testosterone levels were repeatedly found in submissive, fight-avoidant males ranging from rats  and hamsOxytocin (OXT) is a highly conserved neuropeptide found in humans and animals modulating social behavior , 231. InWith a focus on the mesocorticolimbic network, motivation for social behavior is promoted or inhibited by tuning the dopaminergic activity of the VTA and its projections, which is tightly connected to BDNF signaling, a strong regulator of neuronal plasticity . As the As described in detail in the previous sections, hyperactive VTA-NAc dopaminergic projections are a key feature underlying avoidance behavior after psychosocial stressors. In contrast, mesocortical VTA-mPFC projections are hypoactive  with a cThe actions of the circuitry eventually leading to socially avoidant behavior are in large parts connected by glucocorticoid, BDNF, and dopamine signaling and are summarized in Fig. The serotonergic system with its main source in neurons of the dorsal raphe nuclei (DRN) is a modulator of socio-affective, in part GR-driven response independent of the classic HPA axis feedback loop. Treatment of socially avoidant mice with imipramine not only restored social behavior  but also−/−) show phenotypes similar to clinical symptoms of anxiety and depressive disorders [−/− mice show increased aggressive behavior when confronted with an intruder in their home cage [−/− mice when exposed to a novel conspecific, which possibly contributes to enhanced social memory/discrimination in these mice [The ECS and especially the CB1 receptor regulate behavior and stress-responses in rodents . Mice geisorders  and showome cage , 269, whese mice .CB1 signaling particularly affects social relationships between mothers and their offspring. Cnr1-/- dams show deficits in maternal care , which is likely caused by their increased anxiety state and correlated with reduced oxytocin receptor and BDNF expression in the hippocampus . Many ofAnother aspect of social behavior regulated by endocannabinoid signaling is adolescent social play, which is critical for developing social competence in most mammalian species and shows clear sex-differences . Social Next to the amygdala, other brain regions implicated in endocannabinoid effects on social behavior are the ventral hippocampus (vHPC), NAc, and VTA. In mice, social avoidance can be induced by optogenetic activation of BLA-NAc glutamatergic circuits, which could be prevented by systemically increasing 2-AG levels . FurtherFinally, the ECS is critically involved in regulating stress responses and several studies have demonstrated a role for endocannabinoid signaling in the effects of stress on social behavior. In a model of PTSD, pre-treatment with cannabinoid agonists or FAAH inhibitors could prevent deficits in social recognition memory, as well as anxiety- and depressive-like behavior induced by a shocking reminder . SimilarA summary of the modulators and their actions in social avoidance (induction or prevention) of animals is shown in Table In the previous sections, social avoidance has been described and reflected from the viewpoints of human and animal studies as a primarily active withdrawal from social interaction, which can be a physiological, adaptive, and protective reaction to social threat and unpleasant social experience. However, social avoidance is not always fear-driven, but can also result from a decreased need for social interactions and thus be a passive trait  which waThe borderline between an active adaptive or maladaptive response is stepless and even more difficult to define when comparing human and animal behavior. Humans can be subjected to both multimodal self-reporting and investigator-based assessments regarding their behavior, underlying emotions, and cognitions whereas assessment in the most common studies of animal species, rodents, relies on careful observation and measuring. Theory of mind, the ability to take the perspective of others, is a key prerequisite for human social cognition although a recent review summons aspects of a theory of mind also in non-human species like apes, dogs, and some birds . Data onFocusing on circuitry and molecular regulation underlying social avoidance, we found high overlap between species in the mesolimbic dopaminergic system, the limbic regions and the prefrontal cortex. This comes with little surprise as the so called social brain and its components have repeatedly been described as highly conserved in mammals both anatomically and functionally , 294. Th


Perioperative goal-directed haemodynamic therapy (GDHT), defined as the administration of fluids with or without inotropes or vasoactive agents against explicit measured goals to augment blood flow, has been evaluated in many randomised controlled trials (RCTs) over the past four decades. Reported post-operative pulmonary complications commonly include chest infection or pneumonia, atelectasis, acute respiratory distress syndrome or acute lung injury, aspiration pneumonitis, pulmonary embolism, and pulmonary oedema. Despite the substantial clinical literature in this area, it remains unclear whether their incidence is reduced by GDHT. This systematic review aims to determine the effect of GDHT on the respiratory outcomes listed above, in surgical patients.I2 statistics.We searched the Cochrane Central Register for Controlled Trials (CENTRAL), MEDLINE, EMBASE, and clinical trial registries up until January 2020. We included all RCTs reporting pulmonary outcomes. The primary outcome was post-operative pulmonary complications and secondary outcomes were specific pulmonary complications and intra-operative fluid input. Data synthesis was performed on Review Manager and heterogeneity was assessed using We identified 66 studies with 9548 participants reporting pulmonary complications. GDHT resulted in a significant reduction in total pulmonary complications . The incidence of pulmonary infections, reported in 45 studies with 6969 participants, was significantly lower in the GDHT group . Pulmonary oedema was recorded in 23 studies with 3205 participants and was less common in the GDHT group . There were no differences in the incidences of pulmonary embolism or acute respiratory distress syndrome. Sub-group analyses demonstrated: (i) benefit from GDHT in general/abdominal/mixed and cardiothoracic surgery but not in orthopaedic or vascular surgery; and (ii) benefit from fluids with inotropes and/or vasopressors in combination but not from fluids alone. Overall, the GDHT group received more colloid (+280 ml) and less crystalloid (−375 ml) solutions than the control group. Due to clinical and statistical heterogeneity, we downgraded this evidence to moderate.This systematic review and meta-analysis suggests that the use of GDHT using fluids with inotropes and/or vasopressors, but not fluids alone, reduces the development of post-operative pulmonary infections and pulmonary oedema in general, abdominal and cardiothoracic surgical patients. This evidence was graded as moderate.PROSPERO registry reference: CRD42020170361 Albeit uncommon, major surgery can be associated with significant pulmonary complications, increasing morbidity and mortality with a consequent greater burden on resources., functional reserve, smoking status, pre-existing lung diseases and the presence of obstructive sleep apnoea. The commonly reported pulmonary complications are atelectasis, respiratory tract infection/pneumonia, aspiration pneumonitis, acute respiratory distress syndrome (ARDS)/acute lung injury (ALI), pulmonary embolism and pulmonary oedema. Strategies to prevent or minimise post-operative pulmonary morbidity include pre-operative optimisation of pre-existing lung conditions, smoking cessation, pre-habilitation exercise programmes and intra-operative anaesthetic techniques such as increased use of neuraxial techniques, reduced use of long-acting neuromuscular blockade and lung-protective ventilation., EMBASE (week 52 2019) and the Cochrane Central Register of Controlled Trials . The search strategies used are available in the supplementary material. The protocol for this study is registered and accessible on the PROSPERO  Registry (CRD42020170361).2), oxygen consumption (VO2), mixed venous oxygen saturation and oxygen extraction ratio (O2ER). We grouped haemodynamic monitoring techniques into 4 categories: pulmonary artery catheter, oesophageal Doppler, minimally invasive and non-invasive. We defined minimally invasive techniques as using devices that require insertion of an arterial line and/or central venous access (but did not require a pulmonary artery catheter) and used arterial pulse contour analysis, transpulmonary thermo- or lithium dilution to measure dynamic cardiac variables . More recently, studies have evaluated hemodynamic monitoring techniques with the use of bioimpedance/bioreactance and non-invasive pulse contour analysis. These devices were defined as non-invasive cardiac output monitoring. Studies based on a dynamic assessment of plasma volume and fluid responsiveness such as systolic pressure variation (SPV), pulse pressure variation (PPV) or plethysmography variability index (PVI) were excluded as they do not provide a measure of flow.We included all relevant randomised controlled trials with or without blinding and published in the English language. The participants were adults (age > 16 years) undergoing any elective or emergency surgery . Studies of non-surgical patients with trauma or sepsis were excluded. Peri-operative goal-directed haemodynamic therapy was defined as administration of fluids, with or without inotropes or vasoactive agents, against explicit measured goals to augment blood flow and initiated in the pre-operative (≤24 h), intra-operative or post-operative period (≤6 h). We included all invasive and non-invasive monitoring devices used with a pre-defined algorithm to augment flow towards specific haemodynamic targets including the following measured or derived variables: cardiac output (CO), stroke volume (SV), oxygen delivery (DOTwo review authors (PR and MK) independently screened titles and abstracts from the search results to identify all potential studies. The studies were selected according to the inclusion and exclusion criteria and a third independent author (AD) further assessed studies against the eligibility criteria and resolved any disagreements by discussion. From the eligible studies, relevant data such as methods , type of surgery and participants, interventions  and outcomes were extracted. Where data was missing, incomplete or grouped with other outcomes, we attempted to contact authors to obtain additional details if the study was within the 10-year period.We included all studies that reported post-operative pulmonary complications. Our primary outcome was to assess the impact of goal-directed haemodynamic therapy on the incidence of post-operative pulmonary complications. This was presented as the total number of pulmonary events. We assessed individual events as secondary outcomes, as reported by the study authors. We used author-defined definitions for pneumonia, ARDS or ALI, pulmonary oedema, and pulmonary embolism. As it is often difficult clinically to distinguish pulmonary oedema associated with lung injury from fluid overload/hydrostatic or cardiogenic pulmonary oedema, we included this outcome as a pulmonary complication unless otherwise stated as cardiogenic in origin. We also performed subgroup analyses for the type of surgery, the haemodynamic monitoring device used, and the GDHT intervention delivered . We assessed intra-operative fluid administration, separating the use of crystalloids and colloids during the study period when reported.We used the Cochrane risk of bias tool to assess the quality of included studies., as guided by the Cochrane Collaboration.. To assess our dichotomous data, we used Odds Ratios (OR), using the Mantel-Haenszel method with random-effects and fixed-effects models with 95% confidence intervals (CI). Where possible, all our analysis was intention-to-treat (ITT). We assessed statistical heterogeneity by using N = 30), dynamic studies which track pulse pressure or systolic pressure variations with no surrogate indices for global blood flow (N = 13) and studies that used additional goal-directed measures in the control group or compared different fluid solutions in the GDHT setting (N = 11). Ninety-six randomised controlled trials fulfilled our inclusion criteria and of those 67 studies reported post-operative pulmonary complications. One study reported pooled cardiac and respiratory complications and as a result, this was not included for quantitative data synthesis.  of the GDHT group and 14% (676/4776) of the control group. There was a significant difference between groups  Fig. . A randoI2 = 0%, P = 0.0003, 45 studies) and pulmonary oedema . However, there were no differences in ARDS  or pulmonary embolism   and more colloids  administered intra-operatively. There was significant statistical heterogeneity between studies and random-effects models were used for these analyses. Total intra-operative fluid input was presented by 27 studies and the GDHT group overall had less cumulative intra-operative fluid  than controls  and cardiothoracic surgery . No reduction in pulmonary complications was observed in patients undergoing orthopaedic  or vascular surgery .We carried out a subgroup analysis to assess the impact of GDHT on the incidence of pulmonary complications adjusted for the type of surgery Table . There wEach study was also categorised according to their method of monitoring. Most studies 50%) used minimally invasive cardiac output monitoring and the results were not significant for any specific category of technique . This was not evident when the protocol used fluid alone  , 2001 to 2010 , and 2011 to the current period . Most of the studies were conducted within the current decade , these findings are consistent with previously published systematic reviews in this area. and more colloid solutions (280 ml) intra-operatively. Whilst these differences are modest, they may in combination have contributed to maintaining intravascular volume, whilst reducing the development of tissue and pulmonary interstitial oedema. The occurrence of a beneficial outcome in patients receiving more colloid during surgery challenges notions that the use of such fluids has no benefit , guided by the Cochrane Collaboration. Furthermore, most studies reported intra-operative fluid volumes separately for crystalloids and colloids. Some studies reported these as ml/kg/hour and others as a cumulative balance, or total volumes used. Despite these limitations, it appears that in the GDHT group, more colloid and less crystalloid fluids were used during the intraoperative period. Most of the studies (63%) utilised a colloid solution as their fluid of choice in their protocol for fluid bolus regimens and this is the likely explanation for the increased usage of colloids. Others used a combination of crystalloids and colloids (14%), or crystalloids alone (14%) and in six studies the type of fluid was not specified.The risk of bias was an issue among the included studies. Many of the studies (62%) included in this review did not blind the participants or personnel delivering the intervention peri-operatively and as a result, may have increased the risk of performance bias. Although some studies have attempted to blind but ultimately have found it difficult to fully blind the clinicians involved in delivering the therapy. Taking a pragmatic view, it is difficult to blind clinicians performing a continuous intervention that requires feedback and action in real-time and this has been taken into consideration when performing our risk of bias assessment and the interpretation of the results. Overall, the GRADE quality of evidence was graded as moderate due to substantial clinical and moderate statistical heterogeneity with a high risk of bias in several included studies.Despite these limitations, the results of this systematic review and meta-analysis add to a growing body of literature suggesting that GDHT is safe and is effective in reducing the burden of a wide range of perioperative outcomes, in this case, respiratory complications. Whilst clinical adoption of GDHT is recognised to be variable, as the evidence base continues to grow the signal of benefit remains consistent. Understandable concerns about the evidence base are primarily focussed on the clinical heterogeneity, particularly the long duration of time over which these studies have taken place and the associated changes in clinical practice that have occurred, potentially limiting the validity of the findings for current practice. Results from two large (>2000 patient) randomised controlled trials currently ongoing may clarify this picture soon. benefit from GDHT in general/abdominal/mixed and cardiothoracic surgery but not in orthopaedic and vascular surgery; and (ii) no difference between devices used in the GDHT protocols. There was no demonstrable difference in the total volumes of fluid administered but there was greater use of colloid and less of crystalloid solutions in the GDHT group.Additional file 1: Supplementary material Table. A Study characteristics in detail. Supplementary material Figure A: review authors’ judgements about each risk of bias item presented as percentages across all included studies. Green indicates no risk of bias, yellow and red represents unclear risk and high risk respectively


Acute pancreatitis is a sudden inflammation and only last for a short time, but might lead to a life-threatening emergency. Traditional drug therapy is an essential supportive method for acute pancreatitis treatment, yet, failed to achieve satisfactory therapeutic outcomes. To date, it is still challenging to develop therapeutic medicine to redress the intricate microenvironment promptly in the inflamed pancreas, and more importantly, avoid multi-organ failure. The understanding of the acute pancreatitis, including the causes, mechanism, and severity judgment, could help the scientists bring up more effective intervention and treatment strategies. New formulation approaches have been investigated to precisely deliver therapeutics to inflammatory lesions in the pancreas, and some even could directly attenuate the pancreatic damages. In this review, we will briefly introduce the involved pathogenesis and underlying mechanisms of acute pancreatitis, as well as the traditional Chinese medicine and the new drug option. Most of all, we will summarize the drug delivery strategies to reduce inflammation and potentially prevent the further development of pancreatitis, with an emphasis on the bifunctional nanoparticles that act as both drug delivery carriers and therapeutics. The pathology of acute pancreatitis was mainly characterized by stromal edema, vacuolar accumulation, acinar cell necrosis, and inflammatory infiltration of macrophages and neutrophils  and various drugs. These factors could trigger the pathological cellular pathways and organelle dysfunction that culminate in the acinar cell death, local and systemic inflammation, which leads to irreversible pancreatic tissue damage and dysfunction , which hinders the efficient drug delivery from the blood supply toward the inflammatory pancreas, and the other one is that single drug might not be sufficient to manage acute pancreatitis owing to a variety of complex pathologies , a critical lysosomal enzyme. The over released CTSB can cause trypsinogen activation and acinar cell necroptosis. The protective effect of inhibiting trypsinogen activation in acute pancreatitis development was demonstrated in CTSB gene knockout mice  ion promoter was bonded with NF-κB to govern calcium overloading in acute pancreatitis development. Thus, calcium overloading and NF-κB activation might be a mutually interacted pattern.Additionally, studies have demonstrated that calcium ion concentration can activate nuclear factor (NF)-κB signaling pathway, secondary triggering a cascade of inflammatory responses , platelet-activating factor (PAF), etc. Abnormal hemorheology also promoted the development of acute pancreatitis from edema to necrotizing. Platelet-activating factor receptor antagonists (PAF-RAs) was found to significantly reduce local and systemic pathogenesis in acute pancreatitis , which limits the translocation of NF-κB into the nucleus and its binding to DNA. In acute pancreatitis, inflammatory cytokines, e.g. tumor necrosis factor (TNF)-α and interleukin 1 (IL1), could combine with receptors and activate the IkBa kinase, which released the NF-κB from the cytoplasm NF-κB/IkB complex and forming a p50/RelA dimers /NF-κB/aquaporin 8 (AQP8) axis might serve as a potential regulatory pathway to inhibit acinar cell necrosis in early acute pancreatitis  receptor and Toll‐like receptor 9 (TLR9) may also involve in the regulation of NF-κB expression and the oxidation/antioxidation balance, which can be a useful therapeutic target for SAP  and ROS into the interstitium to exert toxicity  is recognized as an important predictor for the persistence and further development of pancreatitis  and yttrium oxide nanoparticles (Y2O3 NPs), could attenuate the oxidative stress by inhibiting the Nrf2/NF-κB pathway. Besides, biomimetic carbon monoxide delivery system can suppress systemic inflammation through inhibiting neutrophil infiltration and HMGB-1 production.In this section, we introduced recent progress of formulation approaches for acute pancreatitis. Formulation strategies were applied to enable the delivery of a therapeutic drug in the body and improve its efficacy and safety by optimizing the pharmacokinetics and targetability to alleviate the pancreatitis development. Here, we emphasized the nanotechnology and biomaterials-based formulations. Nanoparticles could prolong the circulation time and selectively accumulated at the inflamed tissue. Also, these newly developed nanoparticulate formulations could be designed to target the physical characteristics of inflamed pancreas, e.g. weakly acidity and abundant digestive enzymes. Some recent studies also reported neutrophil cell derived membrane camouflaged nanoparticles could disguise as natural neutrophil and actively recruited into the inflamed pancreas after intravenous injection. Other than utilizing the cellular mechanisms of acute pancreatitis for improved delivery efficiency, some nanoparticles could exert drug actions by directly inhibiting the cellular events that contributed to the acute pancreatitis development. For example, polyamidoamine (PAMAM) dendrimers could contributed to the inhibition of NF-κB nuclear translocation in macrophages and reduction in inflammatory cells. Some metal nanomaterial, cerium oxide nanoparticles  nuclear and branched surface groups have been widely used as suitable drug delivery carriers for genes and poorly water-soluble molecules in a variety of disease models linked with oxidative stress , catalase, and GSH, often occurred in pancreatitis, it is acknowledged that the replenishment of antioxidant agents, e.g. NAC, have been recognized as a feasible idea for acute pancreatitis therapy -N-(4-boronobenzyl)-N, N-diethyl-2-(propionyloxy)ethan-1-aminium (PAMAM-(B-DEAEP)), as a gene vector -1, 3- propanediamine (HIPDM) showed high accumulation in the pancreas for imaging in vivo  is a peptide hormone that regulated the endocrine system via different somatostatin receptor isoforms. SST has great potential in the treatment of acute pancreatitis, but its clinical application is hampered by the short half-life in the human body, which is only a few minutes. Cervin et al. designed a lipid-based liquid crystalline nanoparticulate as a carrier to delivery SST, which significantly increased the biological half-life of SST from a few minutes to longer than one hour  has anti-inflammatory effects involving the mitogen-activated protein kinases pathway. CO has been proven to be beneficial in the rodent model for the inflammatory bowel diseases , synthetic octapeptide complex, is the analogue of somatostatin. By removing the enzyme degradation point, octreotide significantly increased the enzyme resistance as compared to that of somatostatin and elevated the half-life of subcutaneous administration to around 100 min  was developed as an example of the injectable thermosensitive gel (GMT1) by intramuscular injection  before imaging the iron particles with an MRI scanner. Intravenously administrated SPIONs can be specifically ingested by macrophages reticuloendothelial system. Since intrinsically magnetic material of SPIONs and vast pro-inflammatory cytokines production induced by macrophages in pancreatitis, SPIONs was used as macrophages labeling agent in preclinically and clinically by MRI  which coordinate a radiotracer  which can be imaged by PET or SPECT. The previous study has synthesized a Gadolinium diethylenetriaminepentaacetic fatty acid (Gd-DTPA-FA) nanoparticles as a diagnostic tool for the early identification of acute pancreatitis (HW et al., 5.Acute pancreatitis is an inflammatory disorder that can be life-threatening in severe cases. For decades, the exact pathophysiological mechanisms of acute pancreatitis remained an enigma which was broken along with the emergence of the concept of autodigestive disease. At present, it was confirmed that the pathogenesis mainly involves premature trypsinogen activation, pathological calcium overloading, pancreatic microcirculation disorders, activation of NF-κB pathway, infiltration of leucocyte cells, and impaired autophagy. More depth mechanisms study still needed to explore more potential targets for acute pancreatitis.Although timely clinical management such as fasting, nutritional support, fluid therapy to improve treatments for patients with acute pancreatitis are productive, there is still no unified criteria for fasting and nutrition. Drug therapy in reducing the secretion of gastric acid, inhibiting trypsin activity and secretion have been studied. However, the combined application of drugs is still in the sporadic observation stage. Traditional Chinese medicine has accumulated rich experience in the diagnosis and treatment of the digestive system. There is no unified standard for its clinical application, and its clinical operability is not strong.Conventional formulations are used to improve the bioavailability, such as chemical modification. Novel drug delivery system provided new sight for treatment and diagnosis for acute pancreatitis, which is mostly devoted to the target delivery for increasing local drug accumulation. Lipid and polymeric nanoparticles are the most common strategies and platforms, which are biocompatible, biodegradable, and relatively stable in biologically relevant media, as well as incline to accumulate in the inflammatory sites owing to appropriate particle sizes and ELVIS effect. Biomaterials with therapeutic effect, such as PAMAM and metal nanoparticles, have also been explored to be applied in the treatment of acute pancreatitis and other inflammatory diseases. By cell membrane surface modification, bioactive drugs can be better transported to pancreas in acute pancreatitis by taking advantages of leukocyte infiltration. Further exploration can focus on the biomimic modification of biodegradable polymers and bioactive particles.Although there are emerging batches of bioactive drug and novel drug delivery system for pancreatitis treatment, many of them are only used in a simple animal model which is insufficient for preclinical studies. The large-sample, multi-center study has not been carried out. Challenging large-scale trials, mechanistic studies and statist support are also needed to help us achieve more effective treatment in acute pancreatitis.


Over the past 10 years, the crisis of sepsis has remained a great challenge. According to data from 2016, the sepsis-related mortality rate remains high. In addition, sepsis consumes extensive medical resources in intensive care units, and anti-inflammatory agents fail to improve sepsis-associated hyperinflammation and symptoms of immunosuppression. The specific immune mechanism of sepsis remains to be elucidated. Reactive oxygen species (ROS) are triggered by energy metabolism and respiratory dysfunction in sepsis, which not only cause oxidative damage to tissues and organelles, but also directly and indirectly promote NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome activation. NLRP3 inflammasomes enlarge the inflammatory response and trigger apoptosis of immune cells to exacerbate sepsis progression. Inhibiting the negative effects of ROS and NLRP3 inflammasomes therefore provides the possibility of reversing the excessive inflammation during sepsis. In this review, we describe the interaction of ROS and NLRP3 inflammasomes during sepsis, provide prevention strategies, and identify fields that need further study. Sepsis is defined as a life-threatening organ dysfunction caused by infection . Based oReactive oxygen species (ROS) are a group of molecules, which include peroxides, superoxide, hydroxyl radical, and singlet oxygen . ROS areThe NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome is a multi-protein complex belonging to the inflammatory pathway of the innate immune system . It is cReactive oxygen species interactions with NLRP3 inflammasomes participate in regulating the immune inflammation responses during sepsis. Studies have reported the mutually reinforcing effects of ROS and NLRP3 inflammasomes. (1) ROS generation partly depends on activation of NLRP3 inflammasomes . (2) ROS2+ overload induced cytochrome c dislocation from the mitochondrial inner membrane, and increased ROS generation by blocking the respiratory chain at complex III , and induce the dissociation of the complex. Under normal conditions, TXNIP is continuously connected to and retained in the reduced state by the ubiquitous TRX . When thAnother potential mechanism involves mtDNA binding. Mitochondria are the sites of ROS production and the main targets of ROS attack. Excessive generation of mitochondrial ROS (mtROS) attacks DNA and generates oxidized bases and strand breaks , which hThe third potential mechanism has some common steps with the second mechanism. The NLRP3 stimulators induce a special form of mitochondrial damage by increasing ROS production. Then, ROS converts mtDNA into an oxidative form to bind with NLRP3 . This thInvestigators have also suggested that mtDNA is insufficient to trigger NLRP3 signaling if the priming step is missing , which mIL-1β released by the mtROS/NLRP3 inflammasome pathway in platelets has been correlated with increased vascular permeability , which mExcessive ROS trigger apoptosis, depending on extrinsic and intrinsic pathways . In the Apoptosis occurs during mitochondrial dysfunction. Highly expressed mtROS has been reported to promote apoptosis by opening mitochondrial permeability transition pores (mPTPs) during sepsis . CytochrCaspase-1 has been shown to promote splenic B cell apoptosis  and lympIt has been shown that anti-apoptotic protein attenuates NLRP3-associated inflammation, which in turn reduces oxidized mtDNA to be released into the cytoplasm . TreatmeAlthough sufficient evidence has demonstrated negative effects of the ROS/NLRP3 inflammasome pathway during sepsis, some studies have also suggested an anti-inflammatory effect of ROS. Autophagy is thought to maintain cellular quality control to regulate innate immune responses, and is therefore adaptive under physiological conditions or mild stress. Autophagy provides a degree of control to promote survival and maintain normal functioning of organs. It is speculated that autophagy is adaptive in the early stages of sepsis. However, when sepsis progresses to a more severe condition, the autophagy response is incapable of completing its function, which leads to unadaptive results .Reactive oxygen species have many times been reported as early inducers of autophagy during low nutrient stress . AMP-actMacrophages show more dysfunctional mitochondria and mtDNA accumulation when under-stimulated by LPS and ATP after depletion of autophagic proteins . Over-acHowever, ROS upregulation of autophagy to inhibit inflammatory responses has limitations. Upregulated autophagy may be insufficient to counteract the NLRP3 inflammasome-induced negative effects of inflammation increases during sepsis. First, autophagy decreases the activation of nucleic acid recognition receptors, and clearance of damaged mitochondria may only occur in the early stage of sepsis, before autophagic proteins are consumed. For example, a recent study showed that the severity of sepsis determines the activity of autophagy. When given a low dose of LPS, to create a model of mild sepsis, autophagy activity was increased proportionately to the degree of damage. However, in the case of severe sepsis, autophagy was not proportional to the degree of damage . This inThe germ theory and antibiotic therapy have limitations. Prevention of sepsis by switching from hyper-immunity to immunosuppression is the key to sepsis treatment, because the latter stage has a high rate of mortality. Based on the known immune injury mechanisms, investigators have used a series of sepsis treatment options, which have been partially successful in both animal experiments and clinical trials. Reactive oxygen species destroy mitochondrial integrity, promote cell apoptosis, and aggravate the inflammatory responses by promoting NLRP3 inflammasome activation in sepsis . StrategIt has been reported that ROS derived from nicotinamide adenine dinucleotide phosphate oxidase inhibits LPS-induced acute inflammatory responses, suggesting that this enzyme induces ROS, which may limit the cytotoxicity and alterations of reduction reactions such as changes in reduced expression of glutathione (GSH) levels during sepsis . GlutathMitoquinone (MitoQ) is one of the most studied mitochondrial-targeted antioxidants, which has been reported to preserve mitochondrial dysfunction during heart failure , and sigNLRP3 activators and the P2X7 receptor are involved in NLRP3 activation and short-lived ROS production . ClearanImproved autophagic activity is beneficial in controlling inflammation responses by maintaining the stability of mitochondrial quality control . For theRapamycin is an inhibitor of the mammalian target of rapamycin (mTOR). A recent study showed its ability to induce autophagy . It playVarious proteins have been shown to maintain the stability of autophagy . SestrinInhibition of NLRP3 inflammasomes has shown great benefit for inflammation control and life extension in sepsis mice . The entThe mitochondrial membrane is a structure, which maintains mitochondrial stability. Swollen mitochondria with ruptured outer membranes are characteristic of sepsis . TriggerMelatonin administration decreases the septic response, reduces inflammation and oxidative stress, and mitigates mitochondrial malfunction . MelatonMitoQ and coenzyme Q are orally active antioxidants that could target mitochondrial dysfunction to balance the oxidative damage and protect the mitochondria. We have reviewed their function and mechanism in the antioxidants section of this review.Traditional Chinese medicines like Fangjifuling and resveratrol are believed to maintain the stability of mitochondrial membranes in a non-specific manner. Fangjifuling has been confirmed to ameliorate LPS-induced renal injury via inhibition of inflammatory and apoptotic responses in mice, and to suppress mitochondrial-mediated apoptosis by regulating the levels of anti-apoptotic proteins . ResveraAlthough animal experiments have been reported, numerous indirect schemes have been developed to reduce oxidative-associated damage, such as mitochondrial protection, activation of the autophagy system to eliminate ROS, and inhibition of NLRP3 inflammasomes. However, considering the potential negative effects, only some substances with antioxidant properties have been used in clinical trials. Clinical data showed decreased expression of antioxidants in patients with sepsis, which may be related to the inflammatory cascade of septic shock . Excess N-acetylcysteine (NAC), an antioxidant sulfhydryl molecule that has shown efficacy in sepsis therapy, is a precursor in the formation of GSH in the body. NAC increased liver blood flow and improved liver function in septic shock patients (patients . Short-tpatients . The propatients , which iHowever, there are some negative reports involving its clinical use. For example, it was reported that high doses of NAC not only failed to improve patient outcomes, but also increased the risk of inflammation, and was associated with increased serum creatinine . Early NVitamin C is a powerful antioxidant with the ability to donate a hydrogen atom and form a relatively stable ascorbic-free radical, which provides protection against oxidative stress-induced cellular damage by scavenging ROS . VitaminSome studies have reported the ineffectiveness of vitamin C in the treatment of infectious diseases. For example, a clinical trial showed that a 96 h infusion of vitamin C did not result in an improvement of the sequential organ failure assessment score, or alter biomarkers of inflammation and vascular injury in sepsis patients . SimilarSelenium is an essential anti-oxidant required for anti-oxidant seleno-enzymes. The erythrocyte selenium concentration was lower in patients who died in the ICU, which may help to predict infection-related hospital mortality . A bolusAnimal experiments have widely reported the antioxidant effect of Coenzyme Q10 in septic mice. Coenzyme Q10 levels were expressed at low levels, and were associated with the inflammatory cascade in septic shock, which indicated that it was negatively associated with vascular endothelial markers and inflammatory molecules . SoltaniSerum melatonin level was positively associated with serum levels of biomarkers of oxidative stress and sequential organ failure assessment score , and wasAlthough there is some controversy about the efficacy of antioxidants in the treatment of sepsis, some combination therapies have been reported to have clinical benefits. For example, combined infusion of vitamin C and NAC improved patient clinical scores in the ICU at day 5, and ultimately decreased patient mortality . In anotSepsis remains a great challenge for public health. In sepsis, oxidative stress responses are increased, followed by ROS over-production, which destroys the integrity of mitochondria and leads to the disorders of energy metabolism. NLRP3 then sense the mtDNA to finish the activation process. Inflammasomes and mitochondria dysfunction are involved in the induction of cell apoptosis. Finally, ROS, NLRP3 inflammasomes, mitochondrial damage, and cell apoptosis form a vicious cycle, leading a second strike on homeostasis, which is independent of bacteria. This second strike by immune inflammation may be the reason for irreversible immunosuppression in the late stages of sepsis, which cause high mortality even under adequate life support in the intensive care unit.Reactive oxygen species act as bactericides, to protect the body from invasion by external microorganisms . In addiIt is well-known that sepsis is characterized by hyperactive inflammation in the early stages and irreversible immunosuppression in the late stages. Future studies should therefore address the roles of ROS and NLRP3 inflammasomes in various pathophysiological and immunology stages in sepsis, to identify ways to manipulate mitochondrial damage and/or mitophagy as a means of modulating apoptosis and inflammatory responses.BRCA1/BRCA2-containing complex 3 is a lysine 63-specific deubiquitinating enzyme involved in inflammasome activity, interferon signaling, and DNA damage repair . A previIt is important to note that mtDNA cannot only be sensed by NLRP3, but also by multi-signaling pathways, such as TLR9 and cyclic GMP-AMP synthase, to induce the progression of sepsis . In addiTheoretically, ROS associated immuno-inflammatory responses can be treated by antioxidants. But recent studies show limited results in both animal experiments and clinical trials. Antioxidants have been used as adjuvant drugs in clinical studies. However, their therapeutic effects failed to receive extensive recognition by clinical doctors and their therapeutic uses are still being debated. Therefore, we may not expect to completely reverse the immune damage of sepsis only by antagonism of ROS, but should pay more attention to a comprehensive therapy management.In summary, sepsis is a disorder with complex immune inflammatory responses involving ROS as the key trigger in the activation of NLPR3 inflammasomes in sepsis. Blocking ROS/NLPR3 inflammasome signals may provide the possibility to reverse sepsis.SZ, YZ, and WH: conceptualization. DW and WH: supervision. SZ and FC: writing – original draft. YZ, WH, and QY: modification.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.