Postoperative cognitive disorders after cardiac surgery may manifest as postoperative delirium (POD) or later as postoperative cognitive dysfunction (POCD). The incidence of POD after cardiac surgery ranges from 16% to 73%. In contrast to POD, POCD is usually diagnosed after the discharge from hospital, with an incidence of 30 to 70% of cases, very often noticed only by close relative or friends, decreasing after six (20–30%) and twelve (15–25%) months after surgery. Perioperative cognitive disorders are associated with adverse short- and long-term effects, including increased morbidity and mortality. Due to the complexity of delirium pathomechanisms and the difficulties in the diagnosis, researchers have not yet found a clear answer to the question of which patient will be at a higher risk of developing delirium. The risk for POD and POCD in older patients with numerous comorbidities like hypertension, diabetes, and previous ischemic stroke is relatively high, and the predisposing cognitive profile for both conditions is important. The aim of this narrative review was to identify and describe biomarkers used in the diagnosis of delirium after cardiac surgery by presenting a search through studies regarding this subject, which have been published during the last ten years. The authors discussed brain-derived biomarkers, inflammation-related biomarkers, neurotransmitter-based biomarkers, and others. Work based on inflammation-related biomarkers, which are characterized by the low cost of implementation and the effectiveness of delirium diagnosis, seems to be the closest to the goal of discovering an inexpensive and effective marker. Currently, the use of a panel of tests, and not a single biomarker, brings us closer to the discovery of a test, or rather a set of tests ideal for the diagnosis of delirium after cardiac surgery. Delirium is a neurobehavioral syndrome caused by a transient disruption of normal neuronal activity mediated by alteration in neurotransmitter and neuronal network function, occurring secondary to systemic (metabolic) disturbances . The DiaDelirium is a strong predictor of worse outcomes and serious complications in hospitalized patients . SimilarDespite the publication of DSM-5 criteria for delirium, up to 75% of patients remain undiagnosed as there is a lack of routine monitoring of delirium in many hospital wards . Some ofThere is a growing interest in the use of objective parameters that may offer a reliable assessment of cerebral damage caused by cardiac surgery, but researchers still look for useful biomarkers, which could help clinicians in their everyday practice to suspect postoperative delirium. Therefore, the detection of elevated or lowered levels of biomarkers, which could serve as predictors or indicators of delirium, seems to be very promising. Moreover, such biomarkers may assist in risk stratification, monitoring of treatment, but primarily may help to diagnose delirium .Delirium can be divided into three subtypes: hyperactive, hypoactive, and mixed . The hypIn the clinical picture of hypoactive delirium, reduced activity, apathy, decreased amount or speed of speech, decreased alertness, withdrawal, unawareness, or hypersomnolence predominate. This subtype may remain undiagnosed due to the insufficient expression of symptoms. Thereby, patients with hypoactive delirium more often suffer from pressure ulcers and hospital-acquired infections . It shouA mixed subtype may be the most common motoric subtype of delirium in intensive care . It is cIn the current literature, the term subsyndromal delirium (SSD) has also been proposed when the patient demonstrates cognitive and attention deficits without meeting all the diagnostic criteria for delirium . This coAnother attempt to classify delirium is based on its etiology and was proposed by Girard et al. This classification includes sedation-associated, sepsis-associated, hypoxic, metabolic, and unclassified delirium subtypes . MoreovePostoperative delirium has been identified more than a half-century ago in cardiac surgery patients and still remains an unresolved problem . The risThe incidence of delirium after cardiac surgery ranges from 16% to 73%, depending on the type of surgery and methodology used for delirium detection. It has been reported that up to 85% of cases remain unrecognized . In the The specifics of cardiac surgery, apart from patient-related factors, add further elements that increase the risk of postoperative delirium. These are related to the use of cardiopulmonary bypass (CPB), the complexity of the surgical procedure, including aortic clamping, and the choice between the on-pump and off-pump techniques, which overlap with the occurrence of patient dependent factors. One of the hypotheses for the development of POD is the development of systemic inflammatory response syndrome (SIRS) not only due to the cardiac surgery itself but also due to the exposure of the patient to the adverse effect of CPB . HoweverSo far, the mechanisms underlying postcardiac delirium have not been fully elucidated. Many different theories and multifactorial processes describe its development, and neuroinflammation is one of them . The injThe important element determining the occurrence of delirium is a disruption in the integrity of the BBB, which consists of the presumed central neuroinflammatory response and which is a consequence of launching multiple potential pathways under the influence of peripheral or systemic factors . The imbThere are additional studies, which underline the role of the intraoperative cerebral desaturation, oxygen delivery and utilization, embolic load, hypo- and hyperthermia, or intraoperative glucose homeostasis , also poStructured assessment and monitoring of postoperative delirium after surgery and anesthesia should be performed in accordance with the European Society of Anesthesiology POD guidelines . NumerouPerforming specific and sensitive neuropsychological tests and examinations that focus on different cognitive domains  is time-This abundance of information and diagnostic options for delirium assessment has led to the issuing of the guidelines that recommend routine use of validated tools. European Society of Anesthesiology (ESA) recommends using a validated delirium score for postoperative delirium screening  .The aim of this narrative review was to identify and describe biomarkers used in the diagnosis of delirium after cardiac surgery, which have been presented in papers published between 2010 and 2020. The authors used PubMed open resource database for this purpose and rejected studies conducted in children and on animals. Specific keywords used were biomarkers, delirium, cardiac surgery, postoperative delirium, POCD, and neuroinflammation.Reliable and rapid assessment of delirium after cardiac surgery is of paramount importance. Biomarker-based diagnostics take on special significance and the benefits of a faster diagnosis of delirium in patients at risk. In some circumstances, this may be lifesaving. The usage of biomarkers as factors, facilitating the diagnosis and monitoring the delirium course, would allow to increase the diagnostic effectiveness, implement early treatment, and reduce the percentage of complications-associated delirium. The ideal delirium marker should be detected earlier than delirium occurrence, should be highly sensitive, correlate with the severity of the disease, stable, translational, easy to obtain, independent of physiological variables, low-cost, readily available, and have high validity and specificity to detect delirium. Moreover, it should be associated with a known mechanism . The search for an ideal delirium marker is a complex process as many confounding factors account for delirious state postoperatively . It is mThere is a growing interest in the use of objective parameters that may offer a correct assessment of cerebral damage caused by cardiac surgery. Biomarkers of the central nervous system (CNS) injury arise after neurons and glial cells damage produced during cardiac surgery; this, in turn, causes active or passive intracellular components release outside CNS. There are two mechanisms in which we are able to detect the biomarkers of injury of the CNS. First, the local biomarker concentration increases in the CNS, and it diffuses into the circulation through the BBB, and the second involves damage of the BBB with unregulated penetration of the biomarker into the bloodstream . FurtherStudies regarding biomarkers in delirium in different clinical conditions laid the groundwork for further, more recent research, and a new pathway for detecting delirium after cardiac surgery. To enable clarity, we divided the biomarkers of delirium after cardiac surgery into the following categories: brain-derived biomarkers, inflammation-related biomarkers, neurotransmitter-based biomarkers, and others. During acute illness, the permeability of the BBB changes. One of the markers of its disruption and the injury of the astrocytes after CNS insult is calcium-binding protein S100 beta (S100B) ,66,67. TAs reported by Fazio et al. and Einav et al. in cardiac surgery, S100B elevation has turned out to be dependent on patient-related factors like age, sex, hypertension, as well as perioperative factors, including the use of cell saver, the presence or absence of extracorporeal pump, the degree of perfusion during and after the cardiopulmonary bypass ,74. ManyTau protein is a microtubule-associated protein involved in stabilizing the axonal cytoskeleton and vesicles transport in the neuronal synapse. Tau hyperphosphorylation is associated with neuronal death observed in neurodegenerative disorders, such as Alzheimer’s disease (AD), and is a well-known marker associated with this disease ,76. In tIt is interesting that Simons et al. also found that ICU patients with hypoactive delirium were susceptible to differentiation from those without delirium by measurement of Tau protein. The authors showed significantly higher levels of serum Tau protein and the Tau/Aβ1–42 ratio in hypoactive patients. In the same study, they also found higher levels of neopterin and IL-10 in hypoactive patients than in the mixed-type delirium group .GFAP is produced by glial cells and astrocytes. Following CNS injury and during neurodegeneration, GFAP gene activation and protein induction appear to play a critical role in the astroglial cell activation (astrogliosis). When apoptosis occurs, GFAP leaks into the CSF and blood, and its breakdown products are released into biofluids, making them strong candidate biomarkers for such neurological disorders . GailiušUbiquitin carboxyl-terminal hydrolase L1 (UCH-L1) is neuron-specific and necessary for normal synaptic and cognitive function . Wang etTogether with S100B protein, neuron-specific enolase (NSE) is one of the most commonly used biomarkers of cerebral injury for the assessment of neurological disorders. Yuan stated that S100B and NSE could be reliable indicators, reflecting the cerebral damages secondary to cardiac surgery . EnolaseResearch regarding UCL-H1, brain-derived neurotrophic factor (BDNF), and metalloproteases-9 (MMP-9) has so far focused on brain injury following cardiac surgery. MMP-9 increase has been reported in patients undergoing cardiac surgery with extracorporeal circulation . Due to Brain-Derived Biomarkers are summarized in Nemeth et al. studied C-reactive protein (CRP) and procalcitonin (PCT) levels for the evaluation of the inflammatory response role in the pathogenesis of POCD . For theKazmierski et al. showed an elevation of IL-2 and TNF-α levels in the postoperative period in coronary artery bypass graft (CABG) patients with delirium, and these results were independent of patient-related factors like age and gender, as well as their psychiatric and physical state and co-morbidities or perioperative factors like CPB time or duration of surgery . AccordiElevated inflammatory biomarkers have been indicated as predictors of dementia and delirium in the general population . InflammNeutrophils and leukocytes are important factors in the development of inflammation . The incIn a retrospective cohort analysis on a total group of 1904 patients, Kotfis et al. studied NLR, PLR, and PWR with CRP for the establishment of an easy-to-obtain predictor of delirium in cardiac surgery patients . The stuStill, further research is needed to describe the relationship between the PWR and delirium. Yet, an inadequate immune system response could play a major role in POD in cardiac surgery as it has been shown by the white blood cells differential count and the CRP increase in delirium patients. In order to obtain an inexpensive, less time-consuming, and possible to use in everyday clinical practice marker of delirium, Kotfis et al. used laboratory data together with an objective pre-operative examination to produce a CARDEL index, which is based on the function of age, glycosylated hemoglobin (HbA1c), and PWR. The analysis showed that the CARDEL index was more accurate in predicting the development of delirium after CABG than any of these factors alone . White cInflammation-related changes in the level of neurotransmitters (deficiency of acetylcholine in the brain) and impaired cholinergic transmission have been described as a potential mechanism for delirium development . HoweverNeopterin is produced by monocytes and macrophages. It can be found in plasma, urine, and cerebrospinal fluid in patients with delirium and is produced due to the traumatic and systemic factors in the development of SIRS . Osse etIn humans, cortisol is one of the stress hormones that, if chronically elevated, has a major influence on the brain by causing damage to the hippocampus and impairing hippocampus-depended learning and memory. Its secretion is proportional and positively correlated with the severity of surgical stimuli . In a stInsulin-like growth factor (IGF-1) has been reported to be involved in the pathophysiology of delirium. The role of IGF-1 is neuroprotective as it inhibits the cytotoxic cytokines . In a study by Çinar et al., the authors found that low levels of IGF-1 before the cardiac operation were risk factors for developing POD . NeurotrIn this narrative review, the authors searched for new data regarding biomarkers used in the detection of postoperative delirium in the last years. Delirium has been constantly a challenging clinical condition. Biomarkers used as an additional element in the diagnostic pathway may contribute to an increased detection rate of delirium and translate into a better quality of postoperative care, also in cardiac surgery departments. Furthermore, the use of biomarkers as a factor, facilitating the diagnosis and monitoring the delirium course, would allow to increase the diagnostic effectiveness and reduce the percentage of complications resulting from an insufficient diagnosis of delirium, which is associated with longer hospitalization, higher treatment costs, and increased mortality ,113. A uResearch regarding biomarkers of delirium after cardiac surgery has been carried out for several years, as has research on other biomarkers of delirium in other clinical conditions. Due to the complexity of the mechanisms of delirium development and the difficulties in diagnosis, researchers have not yet found a clear answer to the question of which patient will be at a higher risk of developing delirium . Of noteOn the one hand, established theories, such as the role of neurotransmitters, inflammation, and stress response in delirium pathogenesis, give researchers the ground to search for an ideal biomarker. On the other hand, most of them lack sufficient evidence or validation for implementation in clinical practice and are not readily available.The majority of the studies suggest that biomarkers could be useful in assessing the delirium risk. Brain-derived biomarkers have an established place in determining the severity of CNS injury and outcomes, but when it comes to delirium, it is not so obvious. This is one of the reasons why researchers should use consistent study methodology to classify inflammatory processes and other independent mechanisms underlying the development of POD. Due to a variety of symptoms and differences in the subtypes of delirium, the diagnosis may be difficult to establish, and delirium often remains unrecognized . It is pFurthermore, it seems unclear whether changes in the levels of biomarkers are associated with or play a causative role in POD after cardiac surgery, or whether they merely represent an acute-phase response to cardiac surgery and CPB. This requires further research. But most importantly, it should be remembered by the clinical teams that effective delirium management is based on early detection of delirium, and the treatment is mainly non-pharmacological. It relies upon the cooperation of different members of the medical, nursing, and physiotherapy teams, as well as family members. It should include effective pain assessment and treatment restoration of senses , early mobility ,116,117,Delirium after cardiac surgery is a common clinical problem that is associated with longer hospital stay and may be characterized by an increased frequency of complications, including increased mortality. So far, no ideal delirium marker has been found for patients after cardiac surgery. Nevertheless, previous work based on inflammation-related biomarkers, which are characterized by the low cost of implementation and the effectiveness of delirium diagnosis, seems to be the closest to the goal of discovering an inexpensive and effective marker. Currently, the use of a panel of tests, and not a single biomarker, brings us closer to the discovery of a test, or rather a set of markers ideal for aiding early diagnosis of delirium after cardiac surgery. This requires further confirmation in clinical trials.


One of the global burdens of health care is an alcohol-associated liver disease (ALD) and liver-related death which is caused due to acute or chronic consumption of alcohol. Chronic consumption of alcohol damage the normal defense mechanism of the liver and likely to disturb the gut barrier system, mucosal immune cells, which leads to decreased nutrient absorption. Therapy of ALD depends upon the spectrum of liver injury that causes fatty liver, hepatitis, and cirrhosis. The foundation of therapy starts with abstinence from alcohol. Corticosteroids are used for the treatment of ALD but due to poor acceptance, continuing mortality, and identification of tumor necrosis factor-alpha as an integral component in pathogenesis, recent studies focus on pentoxifylline and, antitumor necrosis factor antibody to neutralize cytokines in the therapy of severe alcoholic hepatitis. Antioxidants also play a significant role in the treatment but till today there is no universally accepted therapy available for any stage of ALD. The treatment aspects need to restore the gut functions and require nutrient-based treatments to regulate the functions of the gut system and prevent liver injury. The vital action of saturated fatty acids greatly controls the gut barrier. Overall, this review mainly focuses on the mechanism of alcohol-induced metabolic dysfunction, contribution to liver pathogenesis, the effect of pregnancy, and targeted therapy of ALD. ALD is associated with liver inflammation and injury or progressive fibrosis producing three major classes, each of which rarely exists in a pure form ,2. TheseCorticosteroids are used for the treatment of ALD and recently due to the findings of linkage of tumor necrosis factor-alpha with ALD, more focus is given on antitumor necrosis factor antibodies. The previous study suggests that exposure to acetaldehyde from the alcoholic beverage, the acetaldehyde tends to offers the toxic effects of hypotension, tachycardia, facial flushing, and vomiting. Moreover, the higher percentage of alcohol consumption exhibited the effects of neurotoxicity and liver damage . Antioxi2While estimating alcohol consumption, it is to be understood that 12 fluid ounces of beer, four ounces of wine, or 1.5 fluid ounces of distilled spirits all contain approximately 14 g or 0.6 fluid ounces of pure alcohol . Based oAs compared to men, women are more susceptible to ALD pathogenesis. Women tend to develop the advanced liver disease with less alcohol intake substantially . The genIn addition to this are the poorly understood hormonal factors, immunological, social, nutritional, and host factors, all of which have been postulated to play a part in the development of the pathological process ,37. The As a sequela of the injurious processes overlapping secondary to alcohol abuse and HCV infection, the patients may develop an increased liver iron burden and, rarely, porphyria cutanea tarda ,47. In a3Understanding of the detailed pathogenesis of ALD is quite incomplete to date ,50. AlcoChronic consumption of alcohol produces a wide spectrum of hepatic lesions. Fatty liver  is the earliest, most common response that develops in more than 90 percent of drinkers who consume 4–5 standard drinks per day. With continued drinking, alcohol-induced liver disease can proceed to liver inflammation , fibrosis, cirrhosis, and even liver cancer . The complex interaction of various distinct hepatic cell types is crucial to understand alcohol-mediated liver injury ,57. The The liver and gut microbiota axis linked into the bidirectional actions, and this involved the integration factors of genetic, dietary, and environmental. The alteration of the intestinal barrier explains the interrelations of the gut, liver and sometimes leads to negative effects on the liver. The intestinal microbes in hepatic disease are mainly associated with alcohol. This mutual reciprocal action established by the gut derivatives directly enters the liver and leads to intestinal secretions. Alcohol-induced microbial peptides increase the level of proinflammatory mediators in the liver surroundings and this interconnected with the epithelial barrier, the lining of the mucus membrane, and the gut microbiome. In the development of liver pathogenesis, alcohol directly acts on the liver parenchymal cells to initiate the abnormalities of intestinal barrier functions, alteration of microbiota, and increased toll-like receptors (TLRs) activation in liver cells. Especially, the alteration of gut microbiota to contribute to the pathogenesis of liver diseases ,60.3.1The response of the liver to any form of injury is quite limited. The initial and most common histologic response to hepatotoxic stimuli is fatty liver, and that includes excessive ingestion of alcohol. The fat that is accumulated within the perivenular hepatocytes actually coincides with the presence of alcohol dehydrogenase, which is the major enzyme that is responsible for alcohol metabolism. Continuous ingestion of alcohol leads to fat accumulation all through the entire hepatic lobule .Although the extensive fatty change results in the hepatocytes being distorted with the accumulation of macrovesicular fat, stopping drinking results in the normalization of hepatic architecture and fat material inside the liver . While A3.2ALD has varied clinical manifestations. The clinical manifestation of alcohol-induced fatty liver is very subtle in its presentation and is characteristically detected as a consequence of the patient’s visit for a routine screening or employment screening or any unrelated issues. Previously unsuspected hepatomegaly is often the only clinical presentation. Occasionally, a patient with fatty liver is presented with right upper quadrant discomfort, tender hepatomegaly, nausea, and jaundice. Differentiation of alcohol-induced fatty liver and non-alcohol-induced fatty liver is difficult unless an accurate history of drinking habits, pattern, and quantity is obtained .In every possible incidence where liver disease is present, a fully detailed drinking history should be elicited. Alcoholic hepatitis is usually associated with a wide range of clinical features. Cytokine production is thought to be the main factor responsible for all the systemic manifestations of alcoholic hepatitis. Fever, spider nevi, jaundice, and abdominal pain simulating an acute abdomen are the features that are seen at the end of the spectrum, while many patients will be entirely asymptomatic. Identification of the clinical features of alcoholic hepatitis is very important to initiate an effective, appropriate diagnostic and therapeutic plan ,70. Cirr3.3The current diagnosis of ALD is based on the history of alcohol consumption, physical examination, and laboratory findings associated with alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyl transpeptidase (GGTP). The typical abnormalities seen in the laboratory results are nonspecific and include mild to moderate elevations of ALT, AST, and GGTP. This is often accompanied by hypercholesterolemia, hypertriglyceridemia, and sometimes hyperbilirubinemia. In alcoholic hepatitis and contrast to other causes of fatty liver, the AST and ALT are usually elevated fold . HyperbiHowever, all these diagnostic parameters do not predict the degree of liver inflammation. Recent studies have developed several novel clinical criteria scores and biomarkers that provide better diagnostic, prognostic, and possible therapeutic options for the treatment of ALD. The evaluation of hepatoxicity is measured by different parameters such as serum aminotransferases, inflammatory mediators such as cytokines, DNA fragmentation, and investigation of histopathology . Discrim4Preterm birth is diagnosed if delivery occurs between 20 and 37 weeks of gestational age. In a minority of cases, this is iatrogenic as a result of doctors inducing delivery before the expected date due to maternal conditions such as pre-eclampsia and gestational diabetes or fetal conditions such as fetal growth restriction where the benefits of the baby being delivered outweigh that of the remaining in the uterus. However, the majority of preterm births are due to spontaneous labor or is the complication of preterm premature rupture of membranes .Among the many factors considered for preterm birth, substance abuse or alcohol ingestion is considered to be the main . The NatWhile the level of alcohol ingestion could be correlated to the risk of preterm births, there is no exact dose-response relationship between the amount of alcohol consumed during the prenatal period and the extent of damage caused by alcohol in the infant. The alcohol crosses the placenta without restriction . The levConsumption of alcohol during pregnancy causes movement of alcohol through the umbilical cord which then passes to the fetus. Increase concentration of maternal blood alcohol leads to teratogenic effects, including miscarriage, intellectual disabilities, microencephaly, and congenital heart disease. These defects are also known as fetal alcohol spectrum disorders (FASD) ,85.National guidelines from many countries recommend complete abstinence from alcohol during pregnancy to avoid both maternal and fetal adverse effects. Alcohol is a teratogen that impacts fetal growth and development at all stages of pregnancy . Identif5Many drugs are studied for their use in the pharmacotherapy of ALD, but none of the drugs has proven to be safe. Additionally, these drugs can enhance liver toxicity . The curA combination of ribavirin and peginterferon exhibits rare autoimmune adverse effects in hepatitis C and the effect is severe. The cause of autoimmune adverse effects basically from the inappropriate intake of antiviral drugs and these conditions immediately to seek the specific treatment. Combination of these antiviral drugs possessing the autoimmune adverse events and this combination elevated the levels of IgM and IgG. Moreover, there is no linkage between autoimmune adverse events and interferon use .Till now baclofen has been proven safe for the treatment of patients with alcohol-use disease but other drugs suggested by the Food and drug administration (FDA) such as disulfiram and naltrexone can induce hepatotoxicity. So those are not a well-appropriate treatment option for alcohol-induced liver disease patients. Opioids and nalmefene are also FDA approved for the treatment of liver disease, but the safety of these drugs excluded from the registration trial . The tre5.1The treatment of liver disease is limited to alcohol-induced liver disease. The treatment of liver disease is more integrated among health care providers, including physicians and psychologists to achieve abstinence, or at least to reduce the risk of liver toxicity . For thoMany chronic alcoholics are malnourished, it may be either due to intake of too few essential nutrients  or due to the metabolism of alcohol which prevents the body from digesting and utilizing essential nutrients. Also, previous studies reported roughly 60 % of cirrhosis patients had a severe condition of malnutrition ,91.According to the severity of the liver disease, the patient risks are categorized into different levels. Initial support with nutritional supplements includes zinc, magnesium, vitamin D, E, and B1  has encouraged to find new targets conducting different clinical trials. Based on the trials, the new drugs are categorized into four types: a) Drugs that act on the gut axis, b) antiinflammatory agents, c) antioxidants, and d) Drugs with regenerative benefits. The current clinical trials with novel therapeutic agents for the treatment of ALS, particularly alcoholic hepatitis is shown in 5.4Orthotopic liver transplantation (OLT) is one of the popular treatments in severe ALD . After O6Based on the epidemiological and clinical diagnosis of patients with the alcohol-use disorder, the complete treatment is still disappointing. The deficiency of treatment may be influenced by the lack of pharmaceutical approaches in the treatment of alcohol-induced liver disease and required to initiate the awareness program by the governments and health care providers. Moreover, alcohol abuse fully is preventable, so we need to educate the importance of alcohol abstinence among alcohol abuse patients.VS, SC and RJ was responsible for the conception and design of the review. VS, SC, RJ, NKF, SF, IH, AD and WYS collected literatures. VS, NKF, SF, IH, WYS and AD analyzed literatures. VS, SC and RJ drafted the manuscript and WYS, VS and IH drew the figures.The authors declare no conflict of interest.


Cancer immunotherapy suppresses and destroys tumors by re-activating and sustaining the tumor-immune process, and thus improving the immune response of the body to the tumor. Immunotherapeutic strategies are showing promising results in pre-clinical and clinical trials, however, tumor microenvironment (TME) is extremely immunosuppressive. Thus, their translation from labs to clinics still faces issues. Recently, nanomaterial-based strategies have been developed to modulate the TME for robust immunotherapeutic responses. The combination of nanotechnology with immunotherapy potentiates the effectiveness of immunotherapy by increasing delivery and retention, and by reducing immunomodulation toxicity. This review aims to highlight the barriers offered by TME for hindering the efficiency of immunotherapy for cancer treatment. Next, we highlight various nano-carriers based strategies for modulating those barriers for achieving better therapeutic efficacy of cancer immunotherapy with higher safety. This review will add to the body of scientific knowledge and will be a good reference material for academia and industries. Global population projections have projected rising incidences of cancer over the upcoming years, with 420 million new cancer cases anticipated per year by 2025  by TME components promotes the growth of adjacent vessels by attaching in endothelial cells to VEGF receptors (VEGFR). The increasing incidence of angiogenic signals at the TME lead in the development of vessels with damaged or undefined basal cells, resulting in the leakage of the vasculature with a disorderly structure unequally applied around the tumor, with cancer areas enriched by vessels and improperly provided cancer areas  are recruited into the tumor and can facilitate or impede tumor progression as per the chemical composition at the TME  donors, which are capable of improving vascular permeability, were reported to improve the concentration of nanomedicine in tumors up to 2-6 times more than the control group  and its ETA receptor, by which ET-1 mediates vasoconstriction, are also present in cancer cells to preserve the tumor vessel contractile signal. The frequency of expression of ET1 and ETA in tumor vessels was 13 and 5 times greater than that of regular vessels balanced in scale, accordingly  or immune control blockade . As near to the tumor site, HAase cleaves HA, which causes the crosslinking of certain nanocarrier elements, creating depots that are slowly destroyed by the TME acidity. Once packed with TNF-related apoptosis-inducing ligand and anti-angiogenic drug cilengitide, such carriers resided at the tumor site, collated in depots, continued cargo activation, decreased tumor vascularization, and slowed significantly tumor growth without adverse side effects. Furthermore, those who recommended that this platform for NPs can also be used to carry a wide range of cargo like small-molecule chemotherapeutic agents and immune modulators  are revealed to the surface by dying/stressed cells, released or secreted. DAMPs, including surface-exposed CRT, passively released HMGB1, secreted ATP, and heat-shock proteins that may act as either hazardous signals or immune system adjuvants to induce ICD in cancer cells . The pressure-specific pathways include the release of main DAMPs, including CRT and ATP  may impose antitumor effectiveness by activating tumor cells ICD (Kuai et al., TME has also been involved in growing and metastasizing cancer. With-tumor awareness, tumors are shown to develop in increasingly heterogeneous but diverse microenvironments composed of ECM elements, immune cells, vasculature, TAMs, and CAFs. Recent advances indicate that TME modification as well as its unusual structure is an effective technique for curbing tumor growth, invasion, and metastasis. New strategies for addressing the increasing cancer challenge have grown with the introduction of nanotechnology in the drug discovery field. Even so, the sophistication of the TME has already shown an important so far provocative role in the regulation of deeper nano-chemotherapeutic tumor absorption and consequently its biochemical mechanisms. Strategies have been proposed to tackle this challenge utilizing nanotechnology to resolve the resistance mechanism caused by the tumor coverage.


The ongoing COVID-19 pandemic has caught the attention of the global community and rekindled the debate about our ability to prevent and manage outbreaks, epidemics, and pandemics. Many alternatives are suggested to address these urgent issues. Some of them are quite interesting, but with little practical application in the short or medium term. To realistically control infectious diseases, human, animal, and environmental factors need to be considered together, based on the One Health perspective. In this article, we highlight the most effective initiatives for the control and prevention of infectious diseases: vaccination; environmental sanitation; vector control; social programs that encourage a reduction in the population growth; control of urbanization; safe sex stimulation; testing; treatment of sexually and vertically transmitted infections; promotion of personal hygiene practices; food safety and proper nutrition; reduction of the human contact with wildlife and livestock; reduction of social inequalities; infectious disease surveillance; and biodiversity preservation. Subsequently, this article highlights the impacts of human genetics on susceptibility to infections and disease progression, using the SARS-CoV-2 infection as a study model. Finally, actions focused on mitigation of outbreaks and epidemics and the importance of conservation of ecosystems and translational ecology as public health strategies are also discussed. Following the emergence of antibiotics and vaccination, many scientists and physicians believed that infectious diseases would cease to be major public health problems, and non-infectious chronic diseases would become more important in terms of public health, a phenomenon known as “epidemiological transition”. However, as a result of the emergence of new human pathogens, the re-emergence of many infections, and problems in controlling endemic diseases, infectious diseases remain major public health problems, along with non-infectious chronic diseases (Considering disability-adjusted life years (DALYs) or number of infected individuals, the major infectious diseases on global scale are tuberculosis and other respiratory infections, HIV/AIDS and other sexually transmitted diseases, yellow fever, malaria, dengue and other mosquito-borne diseases, viral hepatitis, rabies, cholera, African trypanosomiasis, Chagas disease, leishmaniasis, cysticercosis/taeniasis, dracunculiasis, echinococcosis, cystic echinococcosis, trachoma, foodborne trematodiasis, lymphatic filariasis, onchocerciasis, schistosomiasis, ascariasis, trichuriasis, hookworm disease, Buruli ulcer, leprosy, and yaws . Private companies can contribute to vaccination efforts by allowing their employees to take their children to vaccination stations during working hours, without discounting their salaries. Moreover, public-private partnerships with the objective of reducing production costs and improving the distribution of vaccines are essential, especially in developing countries and during epidemic periods  is the initial step for the treatment of infected individuals. Second, individuals who know they are infected with a particular infectious agent can take measures to avoid its transmission. Third, large-scale testing enables the identification of the populations or communities most affected by a given infection, allowing mapping the areas where the problem is most pronounced and directing control and prevention policies more robustly to these target populations and specific locations. Four, virological surveillance trough the identification of viral strains  estimates recent infections and provides crucial data of viral epidemiology .More investments on POC tests associated with innovation and improvement of diagnostic tests will impact global health, especially in areas and populations with limited resources, where there is insufficient access to laboratories able to perform infectious disease testing . For example, conducting extensive tests for liver infections in the general population is likely to result in many negative and few positive results, at a high cost. On the other hand, targeting testing programs at individuals with risky behaviors is likely to result in the identification of a higher number of infected individuals at a lower cost . For exaSistema Único de Saúde - SUS)  . In brieTreatment is the next expected step after an infectious disease is diagnosed. The treatment of infectious diseases has a pivotal effect on the life quality of infected individuals, reducing unwanted impacts of the disease on social and economic aspects, along with the avoidance of possible co-infection-related complications for the patient, such as for those co-infected with HIV and hepatitis C virus  showed tAntimicrobial drugs are one of the main tools that humanity has to treat numerous infectious diseases and includes antibiotics, antivirals, antifungals, and antiparasitic agents. Among antimicrobial drugs, antibiotics have a prominent role due to their extensive use worldwide and the variety of therapeutic classes , being used to treat several bacterial diseases, such as tuberculosis, gonorrhea, and leprosy. Humanity has benefited dramatically from the use of antibiotics, which have reduced both morbidity and mortality from bacterial infections. However, the indiscriminate and often inappropriate use of antibiotics in humans and other animals associated with the disposal of these drugs in the ecosystems has resulted in the selection of multi-resistant microorganisms. Antimicrobial resistance is currently one of the biggest problems in the field of infectious diseases. There is an urgent need to develop new antimicrobial drugs to be used in the treatment of infections by multidrug-resistant strains .Between 58-75% of infectious diseases that affect humans are originated from microorganisms hosted in non-human animals. In other words, the majority of human infectious diseases have a zoonotic origin .The handling and consumption of meat, blood, and offal from wild animals (bushmeat/wildmeat) are very common in different regions worldwide, mainly in Asia and Africa, although in other regions of the world the bushmeat consumption is also very intense, as in Brazil (Manis javanica) (The Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) emerged in China in 2002-2003, and the Middle East Respiratory Syndrome Coronavirus (MERS-CoV) emerged in the Middle East in 2012, both as a result of the close interaction of humans with animals . Again, avanica) . In thisConsidering the plethora of pathogens in wild animals and the intense interaction of humans with these animals, spillover events resulting in outbreaks and epidemics will repeatedly happen in human history. Thus, the way to reduce these events is to limit the interaction of humans with wild animals, mainly with mammals and birds . A compelling and cost-effective way to achieve this goal is to limit the wildlife trade and wildlife-derived products, especially in countries where bushmeat consumption endangers wild species .Besides bushmeat, the trade of exotic animals to be used as pets also narrows the barriers between humans and exotic pathogens. Thus, the trade of exotic animals must be combated intensely. In addition, it is essential to make exotic pet owners and professionals who work in direct contact with animals  aware of the risks related to zoonosis and emerging diseases, potentially minimizing the risks of infections and spillover events . Revisiting the Nipah virus and avian influenza (H5N1 virus) cases, Human contact with livestock animals also facilitates the emergence of new human diseases, since numerous animals (and their pathogens) come into contact daily with humans whose work involves handling these animals. Of note, swine are prone to infection by avian and human influenza viruses, which allows the mixing of genetic information from different, but closely related, viral species . This process facilitates the generation of new viral strains, including pandemic influenza viruses. As a consequence of this process, swine are considered “mixing vessels” for influenza viruses , loss of water cycle regulation, and other environmental disturbances, fueling the rise in global average temperature and climate changes .Deforestation, biodiversity loss and climate change are highly connected and give rise to a vicious circle, favoring the spread of infectious diseases through many mechanisms. The frequency and intensity of outbreaks and epidemics tend to increase as climate changes become more intense. For these reasons, biodiversity preservation and reduction of climate change must receive special attention on the agenda focused on the control and prevention of infectious diseases , bacteria , and parasites . Mosquitoes of the genus he world , b.The control of vector-borne diseases is a fundamental action to reduce the global burden of infectious diseases. Vector control actions must be implemented at the local level but must be coordinated globally. According to the World Health Organization, effective vector control should include poverty reduction, promotion of good health and well-being, access to clean water and sanitation, development of sustainable cities and communities, climate actions, and partnerships between nations to promote global health . SpecifiAdequate conditions of environmental (basic) sanitation are determinants of population health and include mainly the access to treated water, garbage collection, and sewage system and treatment. Along with vaccination, environmental sanitation is the factor that most contributed to the promotion of public health in the last century . HoweverIn addition to diseases transmitted by contaminated water, the lack of sanitation facilitates the proliferation of mosquitoes that spread numerous viral species . Accordingly, poor water supply services lead people to store water in containers, whereas the lack of adequate sewage systems gives rise to open sewers; these factors prove breeding sites for mosquitoes, contributing to an increase in vector-borne diseases . In addition, an adequate surveillance system must prioritize partnerships between research institutions and public health agencies, focusing on long-term investments, where the training of technical personnel, diagnostic capacity, and rapid responses to outbreaks occurs in an integrated, systemic and lasting manner. Professionals involved in research activities in outbreak situations must be committed to building (or improving) solid diagnostic, healthcare, and surveillance systems at the location where the outbreak occurred. This approach will enable research activities and, in a complementary way, assist in controlling future outbreaks with the help of trained local scientists and health professionals  facilitate the emergence and spread of infectious diseases since these factors are associated with sustained human-to-human transmission of pathogens, lack of sanitation, closer contact with wildlife, garbage accumulation, and proliferation of disease vectors , focused on the prevention of HIV infection . PrEP coIn 1878, Louis Pasteur established that germs were causative agents of infectious diseases. After the “Germ Theory of Diseases” was accepted, it became evident that personal and familial hygiene practices were effective in reducing the occurrence of infections. The connection between hygiene practices  as an effective way to avoid infections and reduce human mortality had been supported by robust and multiple evidence . Although the pivotal role of personal hygiene practices as a strategy to prevent diseases is well established in high-income countries, this is still not the reality for many low-income nations due to the lack of knowledge or scarcity of structure for the distribution of treated water, sewage collection, and appropriate kitchens and bathrooms. To reduce the diseases associated with the lack of personal hygiene, governments need to ensure adequate housing conditions for the population, with proper sanitary installations, in addition to investing in education on how to prevent diseases linked to poor hygiene. In high-income countries, simple hygiene practices should be reinforced, such as hand washing after touching or manipulating structures for public use. These simple measures are of crucial importance to contain the spread of viral infections, especially in the months of seasonal pathogens’ circulation . The nutritional status significantly influences the susceptibility and pathogenesis of infectious diseases in several ways. For example, protein deficiency and malnutrition increase the susceptibility to infections, and facilitate the pathogenesis of diseases, including HIV infection, malaria, and tuberculosis  is facilitated in poorly ventilated spaces and inadequate housing, factors commonly observed in the homes of the low-income populations, in which many people live together in small spaces  whereas others will not be infected (reduced susceptibility or resistance to infection). Also, a remarkable feature observed in most infectious diseases is inter-individual phenotypic variability, with infected individuals presenting clinical features ranging from asymptomatic infection to fatal outcome during clinical progression. In many diseases, this clinical variability depends on immune responses against pathogens, which are influenced by host genetic factors .CCR5 gene (CCR5∆32) are highly resistant to HIV infection  alleles are the prototypical candidates for genetic susceptibility to infectious diseases since HLA molecules are responsible for presenting viral antigens to CD4+ T cells  levels are an important hallmark of severe COVID-19 cases, being associated with a higher risk of death . Due to loci  database analyzed the cumulative effect of genetic variants on ACE2 and TMPRSS2 expression in individuals from five different human populations  from the 1000 Genomes project . This stin silico analysis found that HLA-B*46:01 allele predicted poor binding affinity for all SARS-CoV-2 peptides, suggesting an association of this allele with higher COVID-19 severity  is a susceptibility locus for COVID-19-related respiratory failure  was recently created with the objective to collect, share and analyze host genetic data to understand the role of genetic determinants of susceptibility to SARS-CoV-2 infection and COVID-19 progression. Of note, homogenized protocols for phenotype clinical classification is highly important in studies addressing the immunogenetic aspects of infectious diseases. Also, bioinformatics approaches used for the prediction of candidate targets for immune response against SARS-CoV-2 contribute to vaccine designs  potential polymorphisms associated with susceptibility or resistance to SARS-CoV-2 infection; 2) the identification of host genetic factors that modulate COVID-19 progression; 3) putative epitopes for vaccine design; 4) insights into potential therapies and SARS-CoV-2 pharmacogenetics.In view of the public health risk posed by outbreaks, epidemics and pandemics, it is important that countries act together in undertaking measures to contain the spread of pathogens and mitigate diseases. Strategies such as travel restrictions, vaccination campaigns, surveillance and reporting of cases are examples of containment measures. When prevention and control measures are not met and an epidemic or pandemic event is established, it is important to focus on interventions to promote disease mitigation. The success of such measures relies on the participation of several stakeholders in all levels, including governments, institutions, communities and individuals. In addition, communication must be effective and clear in order to reach all levels of society, and hence broaden community awareness and participation , launched in 1952, initiatives such as the Global Influenza Program (GIP), the Pandemic Influenza Preparedness (PIP), and the Global Influenza Strategy 2019-2030 have been essential for epidemiological surveillance and development of diagnostic tools, vaccines and antivirals against influenza, as well as for building up laboratory capacity and capabilities to increase the number of tested individuals . The benThe emergence of the SARS-CoV-2 at the end of 2019 was not dealt with equally by the authorities of different countries: while some governments promptly responded by closing borders, establishing lockdown and social distancing procedures, and testing individuals, others disregarded the severity and transmissibility of COVID-19. As a consequence, in few weeks COVID-19 had been declared a pandemic  and, as If on the one hand countries failed in containing the spread of SARS-CoV-2, on the other hand, due to the 2009 influenza pandemic, many countries were prepared for implementing mitigation actions. For example, in Brazil, reference laboratories that are part of the National Influenza Network were already equipped for laboratorial analyses of respiratory viral infection, hence were able to perform molecular analyses of samples from patients suspected of SARS-CoV-2 infection; with the advance of the disease in the country, other healthcare setting, including hospitals and private laboratories, also started to test individuals. In addition to governmental policies and community adoption of quarantine and social distancing behaviors, the world scientific community quickly responded to the emergence of the novel coronavirus by rapidly sequencing its genome, developing diagnostic kits, searching for drugs with antiviral activities against SARS-CoV-2 or able to alleviate COVID-19 symptoms.Technological advances significantly contribute to the improvement of mitigation strategies. As mentioned, few days after SARS-CoV-2 was identified as the etiological agent of the severe pneumonia cases that had started at the end of 2019, scientists were able to sequence and analyze its genome, using deep sequencing and bioinformatic tools  to accelerate the development of vaccines, diagnostic tools and drug research and development for neglected tropical diseases - mainly parasitic, bacterial and viral infections - through innovative research partnership and the sharing of knowledge and intellectual property among its members, which include universities and other scientific research institutions, as well as biotechnology and pharmaceuticals companies . Such anOther mitigation strategies rely on advances in information technologies; for example, mobile phone data provides information about individual’s spatial behavior and mobility  and viral  .During the occurrence of a disaster and the first 0-4 days that follow it, emergency services are the most required. Approximately 4 weeks after the disaster, during the recovery phase, there is an increased risk for the occurrence of diseases with a longer incubation period, as well as vector-borne diseases and chronic diseases; hence, surveillance strategies are important for the prevention of outbreaks, epidemics or, in a worst case scenario, pandemics. Examples are outbreaks of disease resulting from the displacement of people in overcrowded fields and cross-contamination of water sources with fecal material and toxic products (As above-mentioned, one of the main factors that aggravate these outbreaks is socio-environmental vulnerability. For example, every year intense precipitation causes floods and land sliding in different regions of Brazil. Accordingly, in 2013 the state of Acre, located in Northern Brazil and that has a low human development index, experienced serious rainfalls that were followed by outbreaks of leptospirosis; whereas in the Southern state of Santa Catarina, which has a high human development index and also suffered severe rainfalls in 2013, cases of leptospirosis did not increase significantly . Another example is the cholera outbreak in Haiti that occurred 10 months after the 2010 earthquake. While approximately 200,000 people died in the disaster, 665,000 cases of cholera were reported, with 8,183 deaths . NotablyThese examples show that, when planning for the response to natural disasters, emergency services must define the strategies to monitor and contain disease outbreaks that arise weeks after the disaster. Such actions require post-disaster surveillance systems able to quickly detect cases of epidemic-prone diseases (A higher number of people must recognize the preservation of biodiversity and ecosystems as an effective strategy for the prevention and control of infectious diseases. This strategy must be spread among the lay population and scientists from various fields. However, this strategy will only have practical results if applied in a systematic and lasting way, considering medical, economic and social aspects of the populations. Therefore, translational ecology is needed: knowledge and scientific data must be transformed into public policies and laws focused on the protection of biodiversity and ecosystems . Engaginper se, by helping to mitigate or prevent the emergence of epidemics in less favored nations, high-income countries end up preventing such epidemics from reaching their territories, avoiding the socioeconomic impacts generated in a context of epidemic or pandemic. In fact, societal initiatives have already been created, but they are difficult to sustain during “inter-pandemic” periods. Furthermore, in addition to creating an investment fund to prevent epidemics and pandemics, it is extremely important to know where and how these financial resources should be applied (Creating economic strategies to deal with public health emergencies is also essential. In this sense, high-income countries should create a stock capital fund to help poor countries tackle emerging epidemics. Besides the humanitarian issue Investments in the prevention of outbreaks and epidemics encompass hospitals, lab facilities and equipment, vehicles, surveillance networks, knowledge, and human capital. Such investments represent an economically advantageous strategy to follow, especially when compared to the high costs to mitigate the effects of epidemics and pandemics. Considering the current issues regarding climate change and biodiversity loss, outbreaks and epidemics are becoming increasingly common, especially in tropical countries. For these reasons, countries should use “inter-epidemic” periods to prepare themselves economically to deal with epidemic and pandemic periods (The scenario mentioned above reinforces the need for international cooperation to avoid and deal with emerging infectious diseases. International funds focused on the prevention and control of infectious diseases is an urgent necessity . In addiThe multiple interactions between humans and pathogens can be facilitated or avoided depending on the presence or absence of actions for the control and prevention of infectious diseases. Host genetic factors also interfere with host-pathogen interactions, since the genetic background modifies susceptibility to infections and disease progression . Of noteRobust evidence shows that the initiatives here addressed are crucial for the control and prevention of human infectious diseases. Scientists have a fundamental role in the search for alternatives to improve these initiatives. These professionals must also act on the dissemination of the importance of these actions, especially in the most vulnerable populations and regions. Considering the multiplicity of the actions for the control and prevention of infectious diseases, it is necessary to engage professionals from different fields. For example, biologists may commit to the development of new vector control tools and also be involved in the detection of host genetic factor associated with infectious disease phenotypes; veterinarians can contribute for surveillance of pathogenic agents such as protozoa, virus and bacteria in wild and domestic animals; social scientists can act on the identification of populations most vulnerable to infections; geneticists and molecular biologists can improve methods for pathogen detection; and medical scientists can develop better therapies. In other words, the control of infectious diseases must be performed within the One Health perspective, considering human, animal, and environmental drivers of infections. The boundaries between humans and non-human animals must be prioritized, as they are critical for the emergence of new human diseases. Therefore, epidemiological surveillance actions involving human-animal interactions and sanitary control in meat markets are essential for the prevention and control of new infectious diseases.The application of the actions discussed here requires a significant amount of financial resources and the involvement of civil society and government institutions. To achieve these goals, the participation of politicians committed to public policies focused on the environment and health promotion is fundamental. The lack of connection between scientific research and public policies is the reason that often explains why there are flaws in the control of infectious diseases, even though there are already prevention and treatment strategies for many of them.Finally, this article has pointed out the best directions that researchers and decision-makers committed with the control of infectious diseases must follow to perform research activities and promote health among society in a realistic and evidence-based way. Properly selecting the areas and initiatives that best fit the aspirations of researchers and the needs of each population help to optimize the financial resources for infectious disease control initiatives and research focused on pathogens, especially in developing countries where the resources are limited.


A substantial body of evidence supports that the gut microbiota plays a pivotal role in the regulation of metabolic, endocrine and immune functions. In recent years, there has been growing recognition of the involvement of the gut microbiota in the modulation of multiple neurochemical pathways through the highly interconnected gut-brain axis. Although amazing scientific breakthroughs over the last few years have expanded our knowledge on the communication between microbes and their hosts, the underpinnings of microbiota-gut-brain crosstalk remain to be determined. Short-chain fatty acids (SCFAs), the main metabolites produced in the colon by bacterial fermentation of dietary fibers and resistant starch, are speculated to play a key role in neuro-immunoendocrine regulation. However, the underlying mechanisms through which SCFAs might influence brain physiology and behavior have not been fully elucidated. In this review, we outline the current knowledge about the involvement of SCFAs in microbiota-gut-brain interactions. We also highlight how the development of future treatments for central nervous system (CNS) disorders can take advantage of the intimate and mutual interactions of the gut microbiota with the brain by exploring the role of SCFAs in the regulation of neuro-immunoendocrine function. The human body is inhabited by a wide variety of commensal microorganisms collectively called the microbiota. This host microbiota colonizes the skin and several mucosal cavities ; however, it is in the gastrointestinal (GI) tract that these organisms reach extraordinary densities since trillions of bacteria, fungi, and viruses coexist in symbiosis with the host for potential mutual benefit –3. DespiAlthough the precise mechanisms involved in the crosstalk between the gut microbiota and brain remain to be fully determined, there are a number of potential pathways through which the gut microbiota can influence brain function . MicroorThe SCFAs acetate, propionate, and butyrate are the main metabolites produced in the colon by bacterial fermentation of dietary fibers and resistant starch . In addiIn this review, we outline the current knowledge about the involvement of acetate, propionate, and butyrate in microbiota-gut-brain interactions. We also highlight how the development of future treatments for CNS disorders can take advantage of the intimate and mutual interactions of the gut microbiota with the brain by exploring the role of SCFAs in the regulation of neuro-immunoendocrine function.The modulation of gut physiology by the CNS and its effects on gut function such as motility, secretion, blood flow, nociception, and immune function during neurological stressors are well-documented , 29, 30.Although a more compelling causal relationship between altered gut microbial composition and brain dysfunction is still needed, it has been shown that disruption in the neuronal and microbial organization in prenatal and postnatal periods of mammalian development may lead to the onset of neurodevelopmental and other brain disorders later in life , 38–40. Under physiological conditions, activation of immune cells and production of cytokines can have a minor impact in the CNS. However, chronic systemic inflammation, mostly in the form of infections, has long been associated with behavioral alterations and cognitive dysfunction , 51. It Finally, bacterial metabolic byproducts including SCFAs are often considered key candidate mediators of gut-brain communication, and altered SCFA production has been demonstrated in a variety of neuropathologies , 33–35.SCFAs are small organic monocarboxylic acids with a chain length of up to six carbons atoms and are the main products of the anaerobic fermentation of indigestible polysaccharides such as dietary fiber and resistant starch produced by the microbiota in the large intestine , 62. Com+-dependent or sodium-dependent monocarboxylate transporters   . MCTs shctively) , except ctively) . Therefoctively) . In thisctively) , 33–37. ctively) . Thus, tSCFAs improve the gut health through a number of local effects, ranging from maintenance of intestinal barrier integrity, mucus production, and protection against inflammation to reduction of the risk of colorectal cancer –81. AlthAnother mechanism by which SCFAs regulate systemic functions is through the inhibition of histone deacetylase (HDAC) activity, thus promoting the acetylation of lysine residues present in nucleosomal histones throughout various cell populations . This inAlthough only a minor fraction of colon-derived SCFAs reaches the systemic circulation and other tissues, their effects on different organ and systems have recently been widely outlined. One of the best-documented effects of SCFAs is on the immune system since butyrate is capable of inducing Treg differentiation and controlling inflammation , 24, 87.14C-SCFAs into the carotid artery   .Accumulating evidence suggests that SCFAs that cross into the CNS have neuroactive properties. Although the precise mechanisms involved in the action of SCFAs on the CNS remain largely unknown, a multitude of animal studies have shown that they exert widespread influence on key neurological and behavioral processes and may be involved in critical phases of neurodevelopmental and neurodegenerative disorders , 36, 100The development of the nervous system is marked by the sculpting of the neuronal networks shaping the functional neural circuitry that is critical for normal cognitive, emotional, and social domains. In this context, glial cells, especially microglial cells, have been increasingly recognized to play a critical role in the elimination of excess or unnecessary synaptic connections, which is necessary for the maturation and refinement of circuits and connections in the nervous system , 102. Thin vitro and in vivo induces morphological and functional changes in the microglia toward a homeostatic profile and inhibits LPS-induced pro-inflammatory modifications , glial cell line-derived neurotrophic factor (GDNF), and BDNF that regulate the growth, survival and differentiation of neurons and synapses in the CNS also play important parts in learning and memory and in a range of brain disorders have been also shown to be modulated by SCFAs –123. BDN2+ (Because of the similarity of SCFAs with the ketone bodies aceto-acetate and β-hydroxybutyrate (BHB), studies have been conducted to elucidate their role during fasting. Accordingly, fasting has been shown to sharply influence the gene regulation and protein expression of several MCTs, which alters the uptake of SCFAs in the gut and their transport to the brain . The reg2+ . This leIn summary, SCFAs might directly influence the brain by reinforcing BBB integrity, modulating neurotransmission, influencing levels of neurotrophic factors and promoting memory consolidation. However, further studies are needed to understand the precise mechanisms involved in these neuroactive effects.The synthesis of new proteins is necessary for long-term changes in synaptic plasticity and learning –134. In Characterized by behavioral symptoms including communication deficits, repetitive behaviors, and sensitivity to environmental changes, ASD comprises an array of neurodevelopmental disorders . ImbalanProteobacteria and hydrogen sulfide producing Desulfovibrio, raising a question for the causality of microbial metabolites unbalance , thereby disrupting their assembly into neurotoxic oligomers , the maiOral bacteriotherapy through probiotic administration has become a potential treatment option for neurodegenerative diseases such as AD. Accordingly, the 3xTg mouse model of AD treated with probiotics in the early stage showed a promising reduction of inflammatory cytokines and decreased cognitive decline associated with reduced brain damage and Aβ aggregate accumulation . MoreoveBacteroidetes and Prevotellaceae in contrast to increased Enterobacteriaceae and reduced production of SCFAs when compared to matched controls , a synucleinopathy and a multifactorial disorder with strong environmental influence characterized by tremors, muscle rigidity, bradykinesia, and impaired gait . Aggregacontrols . Howevercontrols . In contcontrols . Accordicontrols . This cocontrols . Supportcontrols  as well controls –175.Multiple sclerosis (MS) is a neurodegenerative T-cell-mediated autoimmune disease of the CNS that mainly affects the myelin sheath around motor neurons. Among its etiological factors, the imbalance between pro and anti-inflammatory cells in the immune system seems to play an important role, which is highly affected by the gut microbiota composition and can be aggravated by dysbiosis , 177. GiEfforts to modify the course of amyotrophic lateral sclerosis (ALS) a disease that affects motor neurons but also involves a stronger genetic basis that leads to the premature death of those cells, has focused on the gut microbiota composition and its circulating metabolites . A compaMuch speculation currently surrounds the possible involvement of the gut microbiota in metabolic disorders such as type 2 diabetes and obesity. Compelling evidence have shown that the composition of the gut microbiota is altered in animal models of obesity and subjects with prediabetes or type 2 diabetes compared with controls –186. Desin vivo studies, as showed that acute rectal infusions of sodium acetate and SCFA mixtures increased circulating concentrations of PYY in individuals who were overweight (Animal studies suggest that SCFAs have an important role in the prevention and treatment of obesity-associated insulin resistance , 192. Meerweight –199.The gut microbiota has attracted considerable attention in recent years, putting it in the spotlight of biomedical research. Recent studies have suggested that an intestinal bacteria imbalance plays a role in the development of several disorders. The bidirectional communication that occurs between the microbiota and its mammalian host can be mediated through a variety of mechanisms, and it is clear that the biochemical messengers produced by the microbiota are an important facet of this crosstalk. Convincing evidence exists that SCFAs produced by the intestinal microbiota are involved in gastrointestinal physiology, immune function, host metabolism, and even in development and homeostasis of the CNS.Although our understanding of microbiota-host interactions has considerably increased over recent years, there is still an unmet requirement for a deeper understanding of the complex microbiota-gut-brain communication. Furthermore, since most studies have been conducted in rodents, one must be cautious when translating the effects of SCFAs on humans. Given that SCFAs can regulate CNS processes through direct and indirect means and ultimately shape behavior and cognitive function, a thorough comprehension of how these metabolites participate in these complex gut-brain interactions may aid in developing novel therapeutic targets for treating CNS disorders. Further, through their effects on the development and maintenance of healthy brain function, these metabolites hold the potential for use as dietary interventions with a range of psychological functions.YS, AB, and RF planned, researched, and wrote the 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.


Complex organisms are associations of different cells that coexist and collaborate creating a living consortium, the holobiont. The relationships between the holobiont members are essential for proper homeostasis of the organisms, and they are founded on the establishment of complex inter-connections between all the cells. Non-coding RNAs are regulatory molecules that can also act as communication signals between cells, being involved in either homeostasis or dysbiosis of the holobionts. Eukaryotic and prokaryotic cells can transmit signals via non-coding RNAs while using specific extracellular conveyors that travel to the target cell and can be translated into a regulatory response by dedicated molecular machinery. Within holobionts, non-coding RNA regulatory signaling is involved in symbiotic and pathogenic relationships among the cells. This review analyzes current knowledge regarding the role of non-coding RNAs in cell-to-cell communication, with a special focus on the signaling between cells in multi-organism consortia. In the last 100 years, the postulates that were published by Darwin in his “Origin of the species” have been complemented by the increasing knowledge of Genetics and Molecular Biology. Darwin was responsible for the concepts of natural selection, but, most importantly, for the observation of the phenomenon of organism variation. Post-Darwinism theories of evolution relied on the incorporation of the concepts from Genetics into the theory of natural selection and variation, giving central importance to the genes: genes are responsible of evolution by random mutations using natural selection as a main driving force . Co. Co80]. Understanding the complexity of the coral holobiont would need coordinated efforts to apply advanced molecular techniques in the characterization of different corals from diverse environments . In thisStylophora pistillata. Liew and coworkers discovered at least 50 miRNAs from the coral, five of which  are also conserved in other metazoans [Acropora digitifera, RNA and small RNA-seq experiments were also used to characterize the presence of a non-conserved and thermally-responsive miRNA that putatively regulates genes that are involved in a general abiotic stress response, including protein-coding genes that were related with gene expression regulation, DNA repair mechanisms, tissue morphogenesis, and signaling [Protopalythoa variabilis and Palythoa caribaeorum transcriptome-wide sequencing studies detected 11,206 and 13,240 expressed lncRNAs, respectively, some of them being conserved in higher eukaryotes [P. caribaeorum could act as post-transcriptional modulators of the Ras-mediated signal transduction pathway and components of the innate immune-system, as a part of the molecular response of coral bleaching [The roles of ncRNAs in the coral holobiont fitness are not known, but preliminary data support the idea that they could act as modulators of the biotic or abiotic stress responses. One of the first evidence of the presence of functional ncRNAs in corals was obtained from small RNA-seq experiments that were performed in etazoans . In Acroignaling . Other fkaryotes . Furtherleaching .Aiptasia, a model system for cnidarian-dinoflagellate endosymbiosis, transcriptomic, and small RNA-seq experiments showed that miRNAs are differentially expressed in response to endosymbiont infection. Moreover, Ago2 cross-linking and further immunoprecipitation identified miRNA binding sites on a transcriptome-wide scale and found that the targets of the miRNAs regulated in response to symbiosis include genes that were previously implicated in biological processes related to Symbiodinium algae colonization, suggesting the miRNA-mediated modulation of genes and pathways during the onset and maintenance of cnidarian-dinoflagellate endosymbiosis [miRNAs have been also associated with the establishment of endosymbiosis in corals, despite their involvement in stress responses. In the sea anemone ymbiosis .The isolated data regarding the role of ncRNAs controlling the responses of coral holobiont components against diverse stimuli implicate these ncRNAs in the control of the coral homeostasis. The transverse position of ncRNAs in biology and their demonstrated physiological roles within the coral components also suggested that ncRNAs could act as molecular signals within the holobiont, resembling the already known role of some secondary metabolites that are produced by coral pathogens to hijack its defenses and colonize tissues ,93. HowePlants are very interesting hosts from the point of view of the inter-species communication, because they harbor two well-differentiated niches; the root and the aerial structures that contact different environments . In the Salix alba roots that were exposed to petroleum hydrocarbons determined that the external abiotic stress was responsible for a population shift of the fungal communities that are associated with the tree roots. Under abiotic stress, root-associated fungi shifted from Ascomycota to Basidiomycota genera, and this biological shift was also accompanied by an increase of specific biofilm-forming bacteria responsible for the reduction of contamination stress [Botrytis cinerea produces siRNAs by the action of the Dicer-like proteins DCL1 and DCL2 over long double-stranded RNAs. These siRNAs are transported to the plant tissues silencing specific genes that are involved in the immune response against the pathogen. Additionally, tomato plants that are infected by B. cinereal are able to counteract the fungal siRNA action by the use of small ncRNAs that target and silence DCL1 gene transcript in a bidirectional crosstalk mechanism that regulates pathogen colonization and progression [External stimuli can trigger a plant phenotypic response that is observable in the dynamics of the host and associated microbial populations, but also in the genomic output of the individual holobiont components. For instance, metatranscriptomic studies of n stress . Speciesn stress . In bothn stress . Among tn stress . Other hn stress . Interesn stress ,104. Intn stress . Phytohon stress  in the agression .Musa acuminata [Verticillium dahliae, targeting the mRNA transcripts of the fungal virulence factors Clp-1 and Hic-51 [V. dahliae  that will directly block the production of the defensive tasiRNAs in the plant by inhibition of the dsRNA processing complex [Membrane proteins, called pattern recognition receptors (PRRs), modulate relationships between the plant host and the associated microbiota. These proteins can recognize surface features present in the holobiont microbiota and are linked to the biosynthesis of molecular signals to control the growth of potentially pathogenic organisms. The role of PRRs associated with the production of small ncRNAs is clearly illustrated with the bidirectional relationship that was established between the plant pathogen  pathway C. The ge complex . DespiteThe presence of territories that are clearly related with the biodiversity in the associated holobiont components characterize the anatomic and physiological organization of mammals and other complex animals. Internal cavities, such as the intestine, contain the most diverse associated microbiota, ensured by the microorganisms present in food, but also by the relatively protected environment when compared with other biological niches, such as the skin . The intMycobacterium tuberculosis, which can induce the expression of miR-32-5p and miR-124, both negative regulators of pro-inflammatory cytokine production in macrophages [Escherichia coli, M. tuberculosis, and Helicobacter pylori, causing a negative regulatory effect in the LPS-mediated response, cytokine production, endocytosis, and vesicle trafficking [Pathogen-induced dysbiosis in humans and other mammals results in a coordinated response from the host with the objective of eliminating the pathogenic agent and restoring the system fitness, and they are characterized by a specific gene expression pattern from the host that includes ncRNAs . The rolrophages . Anotherfficking .Salmonella typhimurium synthesizes a ncRNA designated as Sal-1, which is processed inside the host infected cell by a mechanism involving Ago2 and that resembles the final steps of miRNA biogenesis in eukaryotic cells [Pseudomonas aeruginosa [Treponema denticola, Aggregatibacter actinomycetemcomitans, and Porphyromonas gingivalis [Some intracellular bacterial pathogens can also deploy molecular attacks on the host cell by using ncRNAs that are generated from specific transcriptional units, demonstrating the role of RNA molecules as ubiquitous regulators . For insic cells . The proic cells . Similarruginosa  and the ngivalis ; the colPlasmodium-derived EVs that originated from erythrocytes are transferred to endothelial cells, suggesting a possible communication mechanism mediated by signaling molecules and ncRNAs [Plasmodium falciparum cells and a further regulatory mechanism of the parasite mRNA targets [Parasitic infections are other examples of host-pathogen interactions that involve the transference of ncRNAs to a mammalian host . For insd ncRNAs ,138. Ver targets . These c targets ,141 and  targets .Regulatory effects that are exerted by ncRNAs are not exclusively observed in eukaryotic cells, but also in bacteria . During E. coli and Fusobacterium in the intestine. These miRNAs target the yegH and 16S RNA gene transcripts  by the bacteria. I3A will be responsible for the secretion of IL-22 by T-cells and a further increase in the epithelial membrane integrity, protecting the intestine from the colonization of pathogenic microorganisms  and fungi (mycobiome), whose importance is starting to be recognized .d. Characterization of dynamic relationships between different species in model holobionts by the application of the Systems Biology point of view, with the help of artificial intelligence algorithms for the integration of “omics” data, together with environmental factors ,153.


Background: The objective of this study was to investigate the use of ensemble methods to improve the prediction of fetal macrosomia and large for gestational age from prenatal ultrasound imaging measurements. Methods: We evaluated and compared the prediction accuracies of nonlinear and quadratic mixed-effects models coupled with 26 different empirical formulas for estimating fetal weights in predicting large fetuses at birth. The data for the investigation were taken from the Successive Small-for-Gestational-Age-Births study. Ensemble methods, a class of machine learning techniques, were used to improve the prediction accuracies by combining the individual models and empirical formulas. Results: The prediction accuracy of individual statistical models and empirical formulas varied considerably in predicting macrosomia but varied less in predicting large for gestational age. Two ensemble methods, voting and stacking, with model selection, can combine the strengths of individual models and formulas and can improve the prediction accuracy. Conclusions: Ensemble learning can improve the prediction of fetal macrosomia and large for gestational age and have the potential to assist obstetricians in clinical decisions. Excessive fetal growth poses risks to maternal and infant well-being . The terMeasurements taken from prenatal ultrasound imaging are the primary quantitative resources for predicting birth weights and diagnosing macrosomia or LGA. Zhang et al.  took theIn this article, we investigate the use of ensemble methods to aggregate prediction results given by different EFW empirical formulas and the statistical models. The goal of this practice is to improve the prediction in macrosomia or LGA. With ensemble methods, it is not required to select any specific statistical model or empirical formulas. Instead, the prediction capability of each combination of the empirical formulas and statistical models is combined and aggregated to generate a learning procedure that gives the best prediction performance.The Successive Small-for-Gestational-Age Births study (SGA study) was funded by the National Institute of Child Health and Human Development (NICHD), in the National Institutes of Health of the USA in 1983. The study was conducted concurrently by the University of Bergen in Norway, the University of Uppsala in Sweden, and the University of Alabama, USA, from 1984 to 1985 . The ini, 1986, through March 31st, 1988 from nulliparous (parity 1) and primiparous (parity 2) Caucasian pregnant women prior to the 20th gestational week who had a singleton pregnancy and spoke one of the Scandinavian languages. A total of 6354 women were recruited to the study, and 632 of them were excluded from the study, according to the exclusion criteria (n = 432) or due to absence of first prenatal visit (n = 200). The remaining 5722 patients were split into three subgroups. A random sample of 561 patients was first selected. Then, a “high-risk” group of 1384 patients was identified out of the random sample of 561 patients on the basis of five small-for-gestational-age (SGA) risk factors: giving birth to an infant with birthweight below 2750 g in the past, maternal cigarette smoking at conception, pre-pregnancy weight lower than 50 kg, a previous perinatal death, and the presence of chronic maternal disease . The remaining 3777 patients were considered as the “low-risk” group. The patients from the random sample and “high-risk” group were eligible to participate in a detailed follow-up study, during which the women were examined at approximately 17th, 25th, 33rd, and 37th weeks of gestation. For each visit, ultrasound examination was performed, and demographic and medical information were collected. At the end of the Scandinavia SGA study, only 1945 were able to complete the follow-up study.To demonstrate the strengths of ensemble methods in predicting fetal macrosomia or LGA, we took the Scandinavian data in the SGA study that were collected in Norway and Sweden. The Scandinavia SGA data were collected from January 1stIn our study, we restricted the study data to the 1115 women in the Scandinavia SGA study who had all four ultrasound examinations and complete covariate information  in the Scandinavia SGA study. In the ultrasound examination records in the Scandinavia SGA study, there were three fetal measurements: biparietal diameter (BPD), middle abdominal diameter (MAD), and femur length (FL).Here, we developed a four-step ensemble learning procedure to predict macrosomia or LGA from prenatal ultrasound measurements. The output of the learning procedure is the binary classification of either macrosomia or LGA. The prediction of macrosomia and LGA is conducted based upon a set of input features. The primary input features are the sonographic measurements BPDs, MADs, and FLs collected from 17th, 25th, 33rd, and 37th weeks of gestation, as well as gestational age at delivery, in the Scandinavia SGA study. Other features also include maternal age, pre-pregnancy body mass index, parity, smoking status, existing diabetes, and gestational diabetes. In the ultrasound examination records in the Scandinavia SGA study, there were three fetal measurements BPD, MAD, and FL. Melamed et al.  summarizWe built a nonlinear three-parameter mixed-effects logistic model with latent random effects to predict PBWs and derive the classification of macrosomia or LGA ,13. The ic model  for the We compared the above nonlinear mixed-effects models with the following quadratic mixed-effects model implemented in Zhang et al. .yij=X′iThe configuration of Here, we propose to apply ensemble methods , to combThe stacking method ,22 is on reports ,22,24 pr reports  used linIn our investigation, the original dataset was randomly divided into a training dataset  and a testing dataset , stratified by the presence of macrosomia or LGA. For an individual mixed-effects model with a particular EFW empirical formula, the entire training dataset, along with the ultrasound measures and demographic information in the testing dataset, was used to fit the model. The birth time, birthweight, and the true macrosomia or LGA status in the testing dataset were used to evaluate the prediction performance. For ensemble methods, the ensemble learner was trained by the training dataset and tested by the testing dataset.The prediction accuracy of each individual mixed-effects model with a particular EFW empirical formula, as well as the ensemble learner, was assessed by the areas under the receiver operating characteristic curve (AUC), sensitivity, specificity, positive predictive value (+PV), negative predictive value (−PV), positive likelihood ratio (+LR), negative likelihood ratio (−LR), and Youden’s index (sensitivity + specificity − 1) for predicting both macrosomia and LGA.We predicted macrosomia or LGA with the nonlinear and quadratic mixed-effects models described above, and also considered those models with or without the covariates. Thus, four mixed-effects models combined with 26 empirical formulas for EFWs, totally 104 learning models, were fitted. The prediction performance of individual learning models in predicting macrosomia is reported in LGA is defined as a newborn with a birthweight greater than the 90th percentile for gestational age. Here, given the input of sonographic ultrasound measures, both the nonlinear and quadratic mixed-effects models can generate PBWs for each of fetuses at any time point, regardless of its actual birth time. A newborn was classified as LGA if his or her PBW was above the 90th percentile of PBWs of all other fetuses, when the fetuses were assumed to be born at the identical birth time as that newborn. The prediction performance of the nonlinear and quadratic mixed-effects models is reported in Two ensemble methods, voting and stacking methods, were applied to combine the 104 learning models for the prediction of macrosomia. The voting method was implemented by using two approaches: voting from all learning models without selection and voting from the selected learning models. To select among the learning models, a penalized logistic regression was run with either a LASSO, SCAD, or MCP penalty. When the stacking method was implemented, we fit a linear regression model as our meta-learner, either without variable selection or with three variable selection methods, LASSO, SCAD, and MCP. The prediction performance of the ensemble methods for the prediction of macrosomia is summarized in We also applied the voting and stacking methods for the prediction of LGA, to combine the 104 learning models. The voting method was implemented as described in the prediction of macrosomia. When the stacking method was implemented, we fit a logistic regression with positive constraints , withoutWe proposed using ensemble methods to combine the strengths from nonlinear and quadratic mixed-effects models and 26 empirical formulas of EFWs to predict macrosomia and LGA of newborns from sonographic ultrasound measurements. The prediction performance of the ensemble methods was studied with the data from the Scandinavia SGA study. We showed that the prediction performance varied among the empirical formulas and mixed-effects models. The three-parameter mixed-effects logistic model combined with empirical formula 11 in We subsequently proposed applying ensemble methods to aggregate the prediction results from mixed-effects models and empirical formulas of EFWs, to achieve better prediction performance. Our investigation showed that, with the aid of either the SCAD or MCP for model selection, both stacking and voting methods improved the prediction accuracies in predicting macrosomia, as opposed to those from individual statistical models and empirical formulas. The voting method with the MCP for model selection predicted LGA more accurately than the individual statistical models and empirical formulas. In this study, the ensemble prediction algorithms were created from all the prenatal ultrasound measures and birth weights. However, the algorithms can be used to make prediction on macrosomia or LGA with the ultrasound measures only from the first or second trimester, although the ultrasound measures collected in the third trimester or before birth can substantially improve the prediction accuracy. Our current study is a feasibility study that demonstrates the ensemble methods can be integrated with ultrasound examinations to assist obstetricians in clinical diagnosis on whether a pregnant woman will give birth to a large infant, and to further guide clinical interventions for the condition. However, measurable clinical benefits are unclear until they are demonstrated in prospective clinical studies.Our current study has several limitations. The proportion of macrosomia or LGA infants in the Scandinavia SGA dataset is small (15% for macrosomia and 11% LGA of n = 1115 infants). This may largely influence the prediction accuracy given by the individual models and empirical formulas. However, using machine learning methods specifically ensemble methods, can accommodate such imbalanced data, and improve prediction accuracy . In addi