Several neuroimaging studies have shown that listening to music activates brain regions that reside in the motor system, even when there is no overt movement. However, many of these studies report the activation of varying motor system areas that include the primary motor cortex, supplementary motor area, dorsal and ventral pre-motor areas and parietal regions. In order to examine what specific roles are played by various motor regions during music perception, we used activation likelihood estimation (ALE) to conduct a meta-analysis of neuroimaging literature on passive music listening. After extensive search of the literature, 42 studies were analyzed resulting in a total of 386 unique subjects contributing 694 activation foci in total. As suspected, auditory activations were found in the bilateral superior temporal gyrus, transverse temporal gyrus, insula, pyramis, bilateral precentral gyrus, and bilateral medial frontal gyrus. We also saw the widespread activation of motor networks including left and right lateral premotor cortex, right primary motor cortex, and the left cerebellum. These results suggest a central role of the motor system in music and rhythm perception. We discuss these findings in the context of the Action Simulation for Auditory Prediction (ASAP) model and other predictive coding accounts of brain function. In the case of (most) music, we do not merely passively receive temporal patterns, but actively engage with the sound stream by discerning an underlying periodicity. This profound shaping of temporal perception is central to understanding and participation in music, dance and even speech/conversation. In recent years, neuroimaging studies have shown that passively listening to music activates brain regions that reside in the motor system proper. The same neural correlates underlying the creation of music and moving to music appear to be involved even when one is only listening to a musical piece –7.The motor system has received increasing attention in non-purely-motor domains –12. ActiPatel and Iversen  advancedRauschecker  has alsoAnother candidate theory, suggested by Schubotz , is of aThe above theories all posit that cortical motor areas play a role in music listening. Another emerging theme is that of the motor system having a predictive role in perceptual processes. These accounts are primarily in agreement in terms of which sub-areas in the motor system are involved. Schubotz’s framework directly proposes involvement of both lateral PMC and pre-SMA/SMA, while ASAP and Rauschecker’s theory both set the dorsal auditory stream (which includes dPMC) as the primary substrate. However, activated regions within the motor system measured by neuroimaging methods tend to vary between research studies. For instance, numerous music listening experiments report motor activity in both supplemental motor area (SMA) and dorsal premotor cortex (dPMC) – 6. AmonThere are many factors likely to contribute to differences across studies, as each individual experiment has its own musical stimuli that vary in terms of particular characteristics, such as rhythmicity, familiarity, and valence of the music, for instance. Stimuli consisting of highly regular rhythmic structure might engage brain regions important for timing and sequential structure , while others might not. Experiments also vary in terms of what a participant is directed to focus on in these paradigms, ranging from complete passive listening (not attending) to judging beat or other characteristics of the stimuli. Such task demands are also likely to influence which regions are active, as directing attention to a stimulus may encourage focusing on particular aspects of the music, such as its beat or rhythmicity. In the present study, we are interested in discovering what motor regions are engaged during all music perception—those activated during passive listening. We define passive listening as attentive listening while remaining still .Identifying which regions are active consistently across all music listening tasks would help gain insight into the underlying processes and hone existing theories. Many theories outlining the functional contribution of individual motor areas exist, which can be used to determine what particular function is being carried out in a task utilizing that motor region. If one critical component is the dorsal auditory stream, which has a proposed role in motor planning and mapping auditory information onto potential motor acts, we should observe observation in dPMC , 23. If In order to determine which of these regions show reliable and consistent activation during music perception, we employed a meta-analysis of all neuroimaging experiments consisting of music listening using an activation likelihood estimation (ALE) . We predMeta-analyses provide a formal, statistical integration to combine the results of several studies that address a set of related research questions. There are several methods available for the meta-analysis of neuroimaging data and careful consideration was given as to which was most appropriate for this study. First, our study aims were to synthesize neuroimaging data of studies comparing rest and passive listening. More specifically, we wanted to identify regions of consistent activation across studies. Activation likelihood estimation (ALE) meta-analysis  addresseTo perform the ALE meta-analysis, we began by first locating relevant studies. Relevant studies were those that utilized functional brain imaging of healthy subjects listening tasks. We conducted literature searches in Medline and the BrainMap database  using a http://www.brainmap.org/ale/; Research Imaging Center, University of Texas, San Antonio, TX). These were transferred either using brainmap’s Sleuth software (if the studies were located in the brainmap database), which outputs coordinates in the correct format for GingerALE, or were transferred individually by hand. The ALE meta-analysis was carried out in GingerALE. The ALE procedure was as follows: (1) model of single-study activation foci as peaks of three-dimensional Gaussian probability densities with subject-based full-width at half-maximum values [Coordinates  for selected studies were recorded and, where necessary, transformed to Talairach space. Coordinates from individual studies were transferred to a text file formatted for analysis in GingerALE 2.3.6  sumWe split the data into separate studies that used either musicians only or nonmusicians only, with the intention of performing a contrast analysis between the two groups. Unfortunately, there were too few studies in these groups individually (14 experiments in each group), so we were unable to complete this contrast.z values.An inspection of We found evidence for consistent activation of various regions of the brain during passive music listening. As expected, our results showed activation in the primary and secondary auditory areas bilaterally. This is consistent with the existing literature showing that these areas are the critical regions of cortex for processing incoming auditory information . Other aWe were unable to pinpoint activation to any further subregions of lateral PMC , as the activation pattern could be consistent with either dorsal or ventral PMC. The average coordinates for these regions overlap in such a way that neither can be ruled out. This means that premotor involvement could be via dorsal, ventral, or both. The activation of PMC in the present analysis is consistent with both ASAP and the HAPEM framework. However, because we do not know whether this activation is localized to ventral or dorsal PMC, it is unclear if this activity reflects involvement of the dorsal stream, or potentially the action observation network that recruits vPMC for action simulation. Also, given that these clusters only represent aggregate BOLD activation, we do not have insight into the temporal dynamics of this activity, which will be crucial for inference about its origin.M1 activity could reflect either an excitatory or inhibitory contribution, as the BOLD signal does not differentiate the two. Vigneswaran et al.  report tFurther examination of the studies that contributed to the right premotor/primary motor activation cluster reveals that a number of them used tasks that were not passive listening in the same way as passive background listening. For example, Chen et al.  requiredMany studies contributed to the cluster indicating left cerebellum. The activation of PMC and cerebellum during music listening supports predictive theories of the motor system, such that the cerebellum might provide the predictive component in a forward model of the upcoming sensory consequences. The cerebellum may be providing an inverse model for mapping sensory input to the simulated movement that would give rise to that sensation. An investigation of the temporal dynamics of communication among these regions can again provide further insight into the mechanism.While quite a few studies did report activation of SMA and pre-SMA, we did not find corresponding activation in our meta-analysis. We also failed to find evidence of basal ganglia activation. One potential reason for this discrepancy may be that another process on top of passive listening is needed to engage these regions. The generally agreed upon roles of both SMA and the basal ganglia are of sequential learning and timing , 50, 51.It also may be the case that activation of SMA/pre-SMA is only prevalent in musically-trained individuals, who are more likely to attend to and perceive the structural aspects of the music due to their background training. Baumann et al.  report iThese results show that the passive perception of music engages a large and complex network of brain regions. This includes activation of areas in the motor system proper. Activation of the cerebellum and primary and premotor cortices suggests that perceived music is partly processed in areas typically considered as important for action-relevant information only. Recruitment of premotor areas during music listening supports many theories of motor involvement during perceptual tasks , 17, 19.One limitation of the present meta-analysis was that we were unable to obtain data from contacted authors for studies that did not report all of the observed brain activations. It is possible that unpublished or unreported activations may have biased our results toward reporting motor and auditory areas, as studies that do not find activation in these areas of interest are less likely to be reported. This inability to obtain unavailable data also likely contributed to our inability to obtain enough studies for the musician/nonmusician contrast. Further exploration of differential activation in musicians relative to nonmusicians is important for advancing this work. Musicians exhibit plasticity-induced changes perceptual and motor abilities, as well as changes in structural and functional neuronal connectivity –55. In pIn summary, this study adds support to the idea that motor planning activity serves not only to help us move but is recruited for music perception even in the absence of movement. Further exploration will elucidate the functional purpose of this recruitment, as well as why and how different music listening contexts seem to engage slightly different networks. An understanding of the auditory-motor interactions underlying music perception could explain a growing number of findings suggesting an important link between music perception and the action systems of the brain.S1 File(NII)Click here for additional data file.S2 File(DOC)Click here for additional data file.


Approximately one million individuals, an estimated 40% with a diagnosis of Alzheimer’s disease-related dementias (ADRD), reside in assisted living (AL); yet, little is known about their experience or the quality of care provided in AL. Unlike other forms of long-term care (LTC), the licensing, operating, and enforcement requirements for AL falls to the states, which vary dramatically in their regulatory approaches. The overall objective of this symposium is to examine states’ AL regulatory environments and understand if and how the health outcomes of AL residents with ADRD are impacted by states’ regulatory decisions. Presenters will highlight the state variability in the regulation, oversight, resident composition, and outcomes of AL residents with ADRD. The first presentation will describe states’ different regulatory requirements for staffing and admission/discharge criteria as it relates to residents with ADRD and how those have changed over the last decade. The second presentation will report results from a national survey of state agents regarding their oversight and enforcement activities in AL. The third presentation will characterize differences in the resident composition and healthcare utilization among residents with ADRD across states. The fourth presenter will report on the effect of residing in an AL licensed to provide specialized dementia care versus a standard-licensed AL on ADRD residents’ outcomes. The discussant will contextualize findings as they relate to the current state of the AL industry. Results will ultimately inform policy-makers, organizational leaders, and clinicians as they seek the most effective ways to ensure optimal outcomes vulnerable residents with ADRD.


Cells and tissues can sense and react to the modifications of the physico-chemical properties of the extracellular environment (ECM) through integrin-based adhesion sites and adapt their physiological response in a process called mechanotransduction. Due to their critical localization at the cell-ECM interface, transmembrane integrins are mediators of bidirectional signaling, playing a key role in “outside-in” and “inside-out” signal transduction. After presenting the basic conceptual fundamentals related to cell mechanobiology, we review the current state-of-the-art technologies that facilitate the understanding of mechanotransduction signaling pathways. Finally, we highlight innovative technological developments that can help to advance our understanding of the mechanisms underlying nuclear mechanotransduction. During the last two decades, increasing evidence has suggested that the physico-chemical properties of the cell microenvironment and the physical forces exerted by cells and tissues play critical roles in the regulation of physiological and pathological situations. In both contexts, cells must adapt their behavior by converting physical signals into biochemical signals and changes in gene expression by using mechanochemical transduction, or mechanotransduction, signaling pathways.Adherent cells are connected to the extracellular matrix (ECM) through the transmembrane receptor integrins. Mechanical signals can be detected via focal adhesion (FA) sites and translated into biochemical information through integrin-related signaling pathways. The inside tension generated by the actomyosin contractility can be transferred to the ECM through integrins at FAs. As a consequence, FAs serve as crucial sites for both outside-in and inside-out mechanotransduction . AlthougTo answer these open questions, current studies need to stimulate mechanically living cells and tissues and then determine their mechanical and functional responses. Current studies on cell mechanotransduction are mostly limited by the techniques that are available to impose mechanical stimulation at both single cell and tissue levels and, in turn, allow to measure biomechanical and biochemical cell responses. Here, we introduce some basic concepts of mechanobiology and we review recent experimental developments that have significant implications for addressing challenging questions in cellular mechanotransduction.The concept of force in cell biology can be intuitively related to pushing or pulling actions exerted by individual or assembly of cells. Even if the concept of force in cell biology is difficult to define, it exists a wide range of physiological situations where mechanical events are crucial to the establishment of cellular functions. For instance, the division of eukaryote cells requires the assembly of a bipolar spindle, which the morphology mostly depends on the activities of molecular motors that generate pushing or pulling forces on the microtubule-based mitotic spindle  and to their local microenvironment through cell-matrix interactions . Cellular tractions forces occur across small-length scales (nano- to micrometers) in the range of pico to nanonewtons, making challenging a direct experimental measurement. Interestingly, ion channels have been proposed for decades to be central for sensing mechanical forces, but their identity remained largely elusive until the discovery of Piezo 1 and Piezo 2 channels  and biophysical  cues that direct their functions. Cells are constantly remodeling the ECM through synthesis, degradation and chemical modifications. These processes imply important changes in ECM properties , which in turn drive cell fate and maintain tissue homeostasis  (PEG), poly (PVA), poly(2-hydroxyethylmethacrylate) (PHEMA) and poly(acrylamide) (PAAm) can form elastic hydrogels that can reproduce some basic mechanical aspects of soft tissues  Annabi . AlthougIn addition to these works, magnetic hydrogels (M-gel systems)  cultures, cells grow until confluence without any specific spatial organization. Major drawbacks of conventional cultures are therefore the difficulty to manage complex parameters involved in mechanotransduction signaling pathways. To address this limitation, a large effort has been made during the last two decades to develop robust micropatterning techniques for manipulating cell adhesion patterns. Although the first micropatterning methods were introduced more than 40 years ago Carter, , they onin vivo is involved in cell polarization  or active  forces. Interestingly, this technique can be combined with confocal microscopy or total internal reflection fluorescence (TIRF) microscopy for studying the dynamics of cell-substrate interactions  has progressively emerged as a key platform for mapping the mechanical properties of living biological samples on spatially defined areas ranging from few nanometers to several tens of micrometers. By using AFM to probe fibroblasts seeded on polyacrylamide hydrogels with varying stiffness, Solon For larger levels of forces, other techniques have emerged such as optical tweezers  , PDMS, are usually used to form elastic membranes. Strain rates commonly vary from 0.1 to 10 Hz with a typical strain percentage ranging from 1 to 30% to keep the membrane deformation in the linear elastic regime. Uniaxial or biaxial strain field can be applied, depending on the complexity of the strain device. One dimensional (1D), or uniaxial strain, corresponds to the membrane stretch in one direction. In this configuration, the two free edges must be constrained to avoid compression in the direction perpendicular to the strain as a result of the Poisson effect. In two-dimensional (2D) strain devices, a uniform biaxial deformation is obtained from the stretching of a thin elastic membrane. Membrane stretching presents the advantage of being applicable on 2D tissues, providing an average readout from millions of cells. In addition, PDMS membranes are optically transparent and could be prepared with thicknesses ranging from 50 to 250 μm, which are particularly well-suited to perform live stretching experiments on an inverted microscope. Uniaxial stretching experiments have been performed to mimic the deformation of brain tissues during traumatic events. Indeed, it was found that traumatic stimulations of integrins are an important etiological contributor to mild Traumatic Brain Injury (mTBI). Cultures of cortical neurons were stretched with an abrupt one-dimensional strain to reproduce Actin filaments (AFs) are semiflexible polymers with a persistence length of ~17 μm  matrices, however measuring tractions of cells in 3D remains difficult and the nonlinear nature of collagen type I hydrogels, which is already used for 3D cell culture, prevents calculation of traction forces. To address this challenge, vertical cantilevers were molded from silicone elastomers in order to measure forces from tissue constructs composed of few 100 of cells  and spatial resolution in physiological or pathological situations  . As a consequence, physical forces cannot be only considered as basic switches of mechanotransduction signals, but as the key mechanism to propagate signals between cells. Interestingly, recent technological developments allow to study the molecular mechanisms used by cellular forces to alter gene activities by modulating the conversion of mechanical stimuli into biochemical signals. Advancements in force measurement methods will therefore permit to address many remaining open questions surrounding cell-substrate but also cell-cell interactions, such as cadherins. For instance, understanding how mechanical tension exerted on cadherins is converted into biochemical signals and how this signaling in turn leads to changes in cell expression remains an open question in cell biology.The understanding of the molecular mechanisms involved in outside-in and inside-out mechanotransduction signaling pathways requires to elaborate integrated strategies combining super resolution fluorescence microscopy  with biophysical probes and multipatterning of proteins. In addition to these combined imaging techniques, FRET biosensors could be applied to examine force transmission across the cytoskeleton to nuclear envelope proteins, chromatin remodeling or mechanically induced changes within the nucleus. FRET between fluorophores of a single type, known as homoFRET, is a promising method to visualize and quantitatively measure changes in protein ratios upon force application, based on the signal produced when molecules labeled with enhanced green fluorescent protein, such as G-actin, assemble into actin filaments.A further challenge should be devoted to a better understanding of how ECM sensing can activate specific transcription factors and translocates them to the cell nucleus. Indeed, it remains unclear whether chromosome configurations can be altered in response to the modifications of the mechanical properties of the nucleus that can be modulated by changes in the ECM physico-chemical properties. Furthermore, several aspects of Piezo channels must be addressed in the near future to determine the role of specific mechanotransduction processes in regulating physiological and pathological processes. For instance, it will be important to decouple the role of Piezo 1 and 2 that makes them such versatile mechanosensors. In addition, questions about conformational changes leading to channel (in-)activation remain to be answered.in vitro models of organ-level systems required to interrogate mechanotransduction pathways in stem cells but also to realize a precision medicine approach by testing important differences in varied patient cohorts.Finally, a major technical challenge in cellular mechanotransduction concerns the development of synthetic models of the stem cell niche to manipulate the biophysical and biochemical properties of the stem cell microenvironment. Indeed, the discovery of induced pluripotent stem (iPS) cells as patient-specific stem cells represents a breakthrough for the basic cell biology and new therapies. Understanding how stem cell behavior can be regulated by mechanical forces can provide fundamental insights for the design of artificial niches for regenerative therapies. In this context, we envision exciting technical developments for the light-controlled activation of cellular forces, dynamic organoid systems and synthetic niches with a spatiotemporally controlled release of proteins and growth factors. Smart stem cell niches that integrate the control of material properties  and protein patterning to recapitulate cell-cell and cell-matrix interactions is required to identify the ECM cues which are relevant to niche-like regulation of stem cell fate. By guiding collections of stem cells that can assemble in 3D, organ-on-a-chip platforms represent a valuable technology to form realistic DM and SG designed the content of the article. All authors performed literature survey, prepared the figures and wrote the article. All authors edited and reviewed the article before submission.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.


Since then, the field of cellular senescence has witnessed a meteoric rise, with multiple studies highlighting its importance in varied physiological contexts such as cancer, development and ageing. A major recent development in the senescence field has been the creation of mouse models which allow the specific elimination of senescent cells. These genetic tools have allowed scientists, for the first time, to conduct proof-of-principle investigations into the causal impact of senescence during the ageing process and in the context of several age-related diseases. Furthermore, these experiments provided the rationale for the development of a new class of drugs named “senolytics”, that can specifically kill senescent cells, which are now of great interest to academics and pharma companies alike. Non-alcoholic fatty liver disease (NAFLD) is more prevalent in the older and obese population and unrelated to alcohol consumption. It can be characterized by simple liver fat accumulation (steatosis) but it can progress to more severe stages such as non-alcoholic steatohepatitis (NASH), advanced fibrosis, cirrhosis and hepatocellular carcinoma (HCC). Previous studies have demonstrated that during ageing and NAFLD, hepatocytes accumulate markers of cellular senescence. However, until now, it was unclear whether senescence was a cause or consequence of liver disease.Cellular senescence, the irreversible loss of replicative potential of somatic cells, was first described in fibroblasts cultured  Nature Communications we have researched the role of cellular senescence during liver ageing, in obesity and NAFLD. We observed that hepatocyte fat accumulation occurred in parallel with markers of cellular senescence in mice exposed to different dietary regimes and in human patients with different severities of non-alcoholic fatty liver disease. This initial observation led us to postulate that hepatic steatosis may be a consequence of hepatocyte senescence.In a study recently published in the journal Ink4a-postive cells, thereby eliminating them from tissues. We found that drug-induced elimination of p16Ink4a-senescent cells in both aged and high-fat fed Ink-ATTAC mice resulted in a significant reduction in liver fat accumulation. Secondly, we investigated the potential role of senolytic drugs as a therapy against liver steatosis. We found that treatment with a senolytic cocktail of dasatinib and quercetin (D+Q) significantly reduced liver fat accumulation in aged wild-type mice and in obese mice (db/db), which carry a mutation in the leptin receptor .To investigate this hypothesis, we first utilised the Ink-ATTAC mouse model, in which a small molecule AP20187 can induce apoptosis in p16It remains a possibility that the observed reduction in liver fat is the result of non-cell autonomous effects, since none of the previously described interventions is specifically targeting senescent hepatocytes. In fact, previous studies using both Ink-ATTAC mice and senolytic drugs have shown that drug-induced elimination of senescent cells occurs simultaneously in multiple tissues and ameliorates multiple ageing phenotypes. Thus, it is reasonable to assume that reduced liver fat accumulation may be partially the outcome of clearance of senescent cell-types other than hepatocytes.In order to investigate this further, we used a mouse model in which senescence can be induced specifically in hepatocytes via inactivation of the DNA repair gene Xpg. We found that hepatocytes lacking Xpg exhibited increased senescent markers as well as increased fat accumulation. These data support the hypothesis that cell senescence results in fat accumulation in a cell autonomous fashion.Mechanistically it is still unclear why senescent hepatocytes accumulate fat. Previous data suggests that factors such as high fat diet, increased lipid synthesis or decreased lipid catabolism may contribute to steatosis during NAFLD. Hepatic fat accumulation may promote the progression of NAFLD to more severe stages by promoting inflammation, fibrosis and cell death.Data from our group and others have shown that senescent cells have dysfunctional mitochondria, characterized by impaired oxidative phosphorylation and increased generation of Reactive Oxygen Species (ROS). In fact, recent data indicates that mitochondria are an integral part of the senescence program, since ablation of mitochondria alleviates many of the senescent phenotypes.Since mitochondria are the major sites of fatty acid oxidation, we proposed that impaired fatty acid oxidation during senescence could explain fat accumulation. Consistent with this hypothesis, we found that mitochondria from senescent fibroblasts and hepatocytes were less efficient in metabolizing the fatty acid palmitate and were insensitive to inhibition of fatty acid oxidation by etomoxir when compared to young cells .in vitro and in vivo. Furthermore, all these factors have been shown to be modulated by dietary interventions known to impact on hepatic steatosis. Given the complexity and interconnected nature of these processes we speculate that it is unlikely that one single mechanism is driving hepatocyte senescence and that probably a combination of multiple factors is at play.While our study indicates that excessive fat accumulation is a consequence of hepatocyte senescence, it does not answer why hepatocyte senescence is induced in the first place. Telomere damage, increased fatty acids, mitochondrial dysfunction and chronic inflammation are associated with ageing, obesity and liver disease and have been shown to induce cellular senescence In conclusion, ageing and obesity are major risk factors for a variety of age-related disease including NAFLD. Our study demonstrates that cellular senescence is a major driver of hepatic steatosis. Furthermore, it highlights that elimination of senescent cells may be a novel therapeutic strategy to reduce steatosis, thereby ameliorating the progression of NAFLD.In summary, we have revealed a strong association between cellular senescence and liver fat accumulation. Dietary restriction (DR) decreased numbers of senescent cells in parallel to strong inhibition of liver fat accumulation or even fat reduction. Using genetic and drug interventions we were further able to replicate some beneficial effects of DR on liver fat storage. The novelty of our approach is however not in inhibiting accumulation of senescent cells, but in alleviating liver steatosis through direct elimination of senescent cells that have already accumulated. As we took only the first step in understanding the mechanistic basics, it is to future research to elucidate other aspects of this phenomenon.


Structural remodeling of pericytes may present an opportunity to foster pericyte-endothelial communication in the adult brain and should be explored as a potential means to counteract pericyte loss in dementia and cerebrovascular disease. We discuss the pathophysiological consequences of pericyte loss on capillary function, and the biochemical pathways that may control pericyte remodeling. We also offer guidance for observing pericytes in vivo, such that pericyte structural remodeling can be more broadly studied in mouse models of cerebrovascular disease.The biology of brain microvascular pericytes is an active area of research and discovery, as their interaction with the endothelium is critical for multiple aspects of cerebrovascular function. There is growing evidence that pericyte loss or dysfunction is involved in the pathogenesis of Alzheimer’s disease, vascular dementia, ischemic stroke and brain injury. However, strategies to mitigate or compensate for this loss remain limited. In this review, we highlight a novel finding that pericytes in the adult brain are structurally dynamic  Finally, we discuss potential mechanisms underlying the control of pericyte structural remodeling, which may be targeted for experimental exploration or potential therapeutic benefit in the adult or aging brain. We would like to emphasize that the phenomenon discussed in this article refers specifically to the dynamic remodeling of pericyte shape and size rather than the oft-discussed phenotypic (cell fate) or functional plasticity of these cells  or its ligand PDGF-B. Deletion of either receptor or ligand is embryonic lethal, and the microvasculature develops aberrantly because of an inability to recruit pericytes to the endothelium  in mural cells of the dermal vasculature  contributes to the maintenance of a stable, non-leaky endothelium throughout adulthood  correlates with increased BBB permeability within the hippocampus , which accounts for approximately 50% of all dementias including AD  and Cspg4 (NG2). However, recent single-cell transcriptomic data has also revealed zonation in gene expression , Tagln (smooth muscle protein 22-α), and Cnn1 . In contrast, downstream mural cells from capillary to venule zones are characterized by high expression of membrane transporters, such as abcc9 (ATP binding cassette subfamily C member 9), consistent with roles in BBB transport. This may explain why pericytes at the capillary zone preferentially uptake the FluoroNissl dye Neurotrace 500/525 when applied to the brain surface , could help explain our observation following single pericyte ablation, where neighboring processes robustly spread into vacated territories until contact with another pericyte is made.The ability to selectively remove pericytes from an existing vascular network and then track recovery over time provided insight into the physiological consequence of pericyte loss in the adult brain. We examined three modes of pericyte function that are well-established from studies of developing organisms, including regulation of: (1) capillary network structure, (2) BBB integrity, and (3) capillary lumen diameter.in vivo. It will be important to determine if and how aging or cerebrovascular disease makes the vasculature more vulnerable to pericyte loss. Second, we were unable to detect acute BBB leakage from uncovered capillary segments following single pericyte ablation. This was also surprising, as pericyte loss in the developing brain is strongly associated with increased endothelial transcytosis. Even with the use of small molecular weight dyes (1 kDa), which have been previously shown to permeate through a trans-cellular route , with relevance to neurovascular coupling less certain. Further, mixing pericytes functions across different tissues (brain vs. retina) is problematic because pericytes functions and vascular architecture differ. In fact, a recent study using modified tissue fixation procedures suggests that retinal capillary pericytes express high α-SMA , and showed impaired basal tissue oxygen supply using a novel oxygen-sensitive imaging probe , capillary diameters became significantly larger, consistent with the idea of altered basal tone with sufficient pericyte loss (Armulik et al., Little is known about how age or disease-dependent pericyte loss affects basal capillary diameter, blood flow and oxygen delivery. One recent study examined young in vivo imaging methods that allow quantification of pericyte growth, coverage, and capillary flow over time. Among the critical next steps are the need to examine the physiological consequence of pericyte ablation at the adult stage using either precise optical methods (Hill et al., The structural remodeling of pericytes in the adult mouse brain may be essential for maintenance of cerebrovascular health and needs to be broadly explored in models of cerebrovascular disease. This task is facilitated by long-term A-AB wrote the review with feedback from MM, NB and AS.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.


Candida albicans. In this mSphere of Influence article, he reflects on how two papers, “Gene Flow Contributes to Diversification of the Major Fungal Pathogen Candida albicans”  and “Selection of Candida albicans Trisomy during Oropharyngeal Infection Results in a Commensal-Like Phenotype” , made an impact on him by incorporating less commonly investigated mechanisms of genome evolution into the context of microbial adaptation.Matt Anderson works in the field of genetics and infectious disease, with a focus on the human fungal pathogen  Candida albicans. In this mSphere of Influence article, he reflects on how two papers, “Gene Flow Contributes to Diversification of the Major Fungal Pathogen Candida albicans”  and “Selection of Candida albicans Trisomy during Oropharyngeal Infection Results in a Commensal-Like Phenotype” , made an impact on him by incorporating less commonly investigated mechanisms of genome evolution into the context of microbial adaptation.Matt Anderson works in the field of genetics and infectious disease, with a focus on the human fungal pathogen  Candida albicans and, specifically, how they regulate disease outcomes.In most microbial systems lacking meiosis, evolution is considered to proceed through the iterative accumulation of site-specific mutations over time. However, the presence of linear chromosomes and diploid or higher-ploidy states provides frequent additional avenues for adapting to new or changing environments. These include transition between ploidy states and aneuploid formation, recombination among chromosomes, and loss of heterozygosity, a process in which alleles from one chromosome are lost and replaced by alleles from the remaining homolog(s). Importantly, some of these genetic changes are reversible, allowing cells in a population to explore evolutionary space without requiring a full commitment to carry that event into successive generations. Two recent papers have guided my thoughts on how these genetic mechanisms contribute to phenotypic diversity in the commensal yeast and opportunistic pathogen Candida albicans” published by Christophe d’Enfert’s lab significantly advanced descriptions of the breadth of genetic diversity within this yeast , segments of DNA in which one of the diploid alleles has been lost and replaced by the other remaining allele. Construction of the strain phylogeny indicated that sequenced isolates evolved primarily through clonal evolution, with the gradual acquisition of iterative mutations. However, two strain clusters showed strong evidence of genetic admixture, suggesting that mating and parasexual reproduction of isolates from other clades produced these lineages. Analysis of a third cluster previously described as the Candida africana subspecies demonstrated that these strains suffered from reduced growth compared to that of other isolate clusters, likely due to a combination of frequent gene-disrupting mutations and evidence of nearly complete genome-wide LOH.The paper “Gene Flow Contributes to Diversification of the Major Fungal Pathogen is yeast . A colleC. albicans genetic diversity by increasing the number of sequenced strains approximately 9-fold. Unlike in previous reports, isolates from this set were almost entirely diploid. My interpretation of these results is that the prior observation of frequent aneuploidy among C. albicans clinical isolates reflected antifungal drug exposure prior to strain isolation that produced aberrant karyotypes derived from an originally euploid state. Of profound importance was the detection of recombinant isolates encoding genomic tracts identical to consensus genotypes from two different clades. The strong evidence of admixed strains within this study, despite meiosis not having been observed in C. albicans, demonstrated a clear role for the alternative mating pathway, the parasexual cycle, in shaping natural populations colonizing the host. Genetic admixture also provided a solution to the dilemma of Mueller’s ratchet, in which fixation of certain alleles through LOH ultimately lead to reduced fitness and an evolutionary dead end. However, this study also highlighted the C. africana clade as an example of Mueller’s ratchet. These strains encoded a nearly homozygous genome and displayed reduced fitness and disease potential compared to those of other C. albicans lineages. It is possible that these changes may be beneficial in additional untested niches, as they have persisted through evolutionary time and are commonly associated with genitourinary infections. Collectively, these results have challenged my conceptual framework of iterative mutation in C. albicans and refocused my interests toward using parasexual processes and large-scale LOH to dissect genetic mechanisms of phenotypic diversity displayed among strains.Investigation of these isolates built on prior work detailing Candida albicans Trisomy during Oropharyngeal Infection Results in a Commensal-Like Phenotype”  centered not on the abundance or duration of fungal burden but on immune response and recruitment. Unexpectedly, dampened immunity was not due to decreases in epithelial damage, which has been observed in other C. albicans strains capable of establishing commensal persistence in the oral cavity but to adherence and uptake by oral epithelial cells in vitro. These results have led me to view commensal versus pathogen interactions between the host and C. albicans as multifactorial and not an all-or-nothing phenotype. Finally, an incomplete description of the locus or loci contributing to these phenotypes highlights deficits in current approaches to identifying candidate loci within regions of copy number changes to allow targeted manipulation. The existence of these challenges has furthered molded my interest in utilizing the natural processes of parasex and targeted LOH to define the genes that contribute to these processes, with clear applications to commensal-pathogen balances in host niches.This study brings new insight into the genetic determinants that oversee the balance between commensal and pathogen phenotypes. A couple of recent reports have highlighted the homozygosity of specific mutations that regulate the balance between


Alcoholics frequently experience episodes of intense depression and/or severe anxiety. Depressed or anxious alcohol-dependent people often believe that they drink to relieve symptoms of sadness or nervousness. However, research does not unanimously support the prior existence of severe depressive or anxiety disorders as a usual cause of alcoholism. A review of recent literature  on the complex interaction between alcohol dependence and independent anxiety/depressive disorders reveals that if an association between alcoholism and anxiety/depressive disorders does exist, it likely operates in a relatively small subgroup of alcoholics at the same time. Psychological symptoms may carry a worse prognosis for alcohol-related problems, and these symptoms must be addressed early in alcoholism treatment. The relationship between alcohol-use disorders and psychiatric symptoms is both clinically important and very complex . As a tyIt is, therefore, not surprising that more than one out of every three alcoholics has experienced episodes of intense depression and/or severe anxiety . These pTwo recent reviews, however, indicate that research does not unanimously support the prior existence of severe depressive or anxiety disorders as a usual cause of alcoholism . In thisAlcohol Health & Research World, review articles are emphasized. Readers interested in more detailed descriptions of the methods of particular studies, however, are referred to specific citations within those reviews.This article briefly reviews some of the recent literature on the complex interaction between alcohol dependence and the longer lasting anxiety or depressive disorders. The interactions between alcoholism and these disorders are evaluated by posing a series of questions, and the reader is encouraged to review the articles cited in the reference list. In keeping with the guidelines of As many as 80 percent of alcoholics report periods of sadness in their medical histories, with approximately one out of three alcohol-dependent men and women having experienced a severe depression that lasted for at least several weeks and interfered with his or her functioning . SimilarAn alcohol-dependent person who demonstrates such psychological symptoms needs more intense intervention and support than may otherwise be provided, and if not appropriately treated, the symptoms may carry a worse prognosis for alcohol-related problems. High levels of depression are especially worthy of concern, because the risk of death by suicide among alcoholics, estimated to be 10 percent or higher, may be most acute during these depressed states.Once a person becomes deeply depressed, regardless of the cause, he or she may need to be hospitalized and provided with the appropriate precautions against suicide. These steps should be considered even if the patient’s depressive disorder is a relatively short-lived alcohol-induced state. Practitioners can counteract their patients’ depressive symptoms by providing education and counseling as well as by reassuring the patients of the high likelihood that they will recover from their depressions. Similarly, an alcoholic who experiences repeated panic attacks or other anxiety symptoms requires intervention for the anxiety, regardless of the cause. Alcoholics who experience high levels of anxiety or nervousness, including panic attacks, will likely benefit from education and reassurance as well as from behavioral therapies aimed at increasing levels of relaxation.caused by intoxication or withdrawal from alcohol; these psychiatric states are likely to improve markedly during the first several weeks to 1 month of abstinence. Thus, long-term psychiatric treatment does not appear to be required for alcohol-induced psychiatric conditions to be resolved . Several separate lines of evidence cast doubt on the possibility that high proportions of alcoholics have severe, long-term depressive or anxiety disorders. These research approaches lead to three conclusions, discussed below.consequence of preexisting major psychiatric disorders, long-term studies of these young men and women should demonstrate a high rate of psychiatric syndromes before the onset of alcohol dependence.Alcohol dependence has been shown to be genetically influenced and to run in families . The disIndeed, several disorders are more likely to be observed in COA’s than in control groups, including conduct problems, such as difficulties with discipline at home or in school . As citeSchuckit and colleagues have studied the rates of psychiatric disorders in COA’s from a variety of perspectives. First, as cited in a review article, a survey of 18- to 25-year-old male students and staff at a university revealed no higher rates of depressive or anxiety disorders among COA’s compared with control subjects, a finding confirmed by a more intensive evaluation of men in a laboratory setting . Second,Only one notable study of COA’s has demonstrated a higher-than-expected risk for these major psychiatric disorders. As cited in a recent review, this investigation by Mathew and colleaguesA recent review revealed similar results from other studies . For exaA recent report from the Collaborative Study on the Genetics of Alcoholism (COGA) focused on 591 personally interviewed relatives of alcohol-dependent men and women . After cSimilar results have been generated from some, but not all, studies of alcoholism in relatives of patients with severe anxiety disorders. For example, an evaluation of 1,047 adult relatives of 193 subjects with severe anxiety disorders revealed no increased risk of alcoholism among the relatives, with the exception of the relatives of those patients who had exceptionally early onsets of their psychiatric disorders . Nor didanxiety disorders in identical twins of alcoholics with the exception of conditions  that might have resulted from the alcoholism in the person’s twin.Consistent with the generally negative results of these family type studies are the conclusions drawn from a recent study of 1,030 female-female twin pairs . The resIt is important to remember, however, that certain studies show some overlap among depressive, anxiety, and alcoholic disorders in the same family. Many of these studies are mentioned in the Schuckit and Hesselbrock review, including the work by In summary, none of the three types of studies conducted  proves an absence of a relationship between long-term anxiety or depressive disorders and alcoholism. As briefly discussed earlier in this article, the family studies are far from definitive because of difficulties in the methodologies used. It is also important to remember that some studies indicate a potential relationship between alcoholism and anxiety/ depressive disorders. In addition, alcoholism and these psychiatric disorders may operate together within some families, or individual instances may occur whereby a person develops alcoholism as a direct reflection of a preexisting psychiatric syndrome.Conversely, the three types of studies highlighted in this section indicate that if an association between alcoholism and anxiety/depressive disorders does exist, it is likely to operate in a relatively small subgroup of alcoholics. More research is required before an adequate answer can be produced.The first conclusion to be drawn from this review is that many alcohol-dependent people are likely to present with depressive or anxiety symptoms that must be recognized and addressed. These problems contribute to an increased risk for suicide attempts, may be associated with more intense withdrawal symptoms, and may contribute to alcoholism relapse. Appropriate interventions for these psychiatric symptoms include forms of supportive psychotherapy, such as counseling or crisis intervention, and behavioral treatment, such as relaxation techniques and desensitization .Second, the possibility that a longer term anxiety or depressive disorder exists in an alcoholic must always be considered. Perhaps 10 percent of men and 10 to 20 percent of women in the general population develop severe anxiety or depressive disorders ; therefore, it would be logical to expect that at least this proportion of alcoholics also would have similar syndromes. Identifying when an alcohol-dependent person has an independent or long-term major anxiety or depressive disorder requires gathering a careful patient history that searches for evidence of severe psychiatric symptoms either before the onset of severe alcohol-related problems or during a subsequent period of extended abstinence. Similarly, all alcoholics evidencing symptoms of severe depression or anxiety should be followed for approximately 1 month after abstinence to be certain that the depressive and anxiety symptoms are improving, because it is likely that severe symptoms remaining after abstinence for such a length of time may indicate a true independent depressive or anxiety disorder that requires longer term treatment.However, treating most alcoholics’ depressive symptoms might not require the use of antidepressant medications. Although one recent small-scale study presented some promising results using these medications , most reSimilarly, in the absence of clear evidence of a long-term major anxiety disorder that predates the onset of alcoholism or that remains intense after an extended period of abstinence, few indications exist for using medications related to anxiety for alcoholics. Panic attacks that are likely to develop during alcohol withdrawal are also likely to diminish in frequency and intensity on their own without medications . BecauseFortunately, several important ongoing studies will help answer some remaining questions regarding the treatment of coexisting depressive or anxiety disorders in the context of alcoholism. The COGA investigation will gather more data regarding potential alcoholic subtypes and will continue to explore possible genetic linkages between alcohol dependence and major depressive and major anxiety disorders. Certain ongoing treatment studies also are further evaluating the potential usefulness of buspirone, some specific anti-depressants, and other medications that affect brain chemicals as potential components for treating alcoholism. Each of these studies is taking steps to evaluate the importance of these psychiatric medications while considering whether subjects’ depressive or anxiety syndromes are likely to be alcohol induced or may indicate longer term independent psychiatric disorders.


Mechanisms of development are frequently studied by modifying the genetic or regulatory controls in one group and comparing it with a wild type group. Such comparisons can be made at multiple scales. In mouse embryos, it is quite common to compare whole mounts often enhanced with LacZ expression. Gene expression patterns using fluorescence microscopy with several reporter fluorescent proteins knocked in are also very common. However, quite frequently, one wants to make comparisons at a cellular level with high-resolution microscopy. Attempting to obtain equivalent sections from fixed and cut blocks is well known to be problematic. No matter what the care in mounting specimens and in prescribing angulations of the cuts with the microtome, one very seldom ends up with histological sections which are directly comparable over several different individuals. Sectioning of multiple adjacent sections helps fill in the need for a three-dimensional representation; however, it remains an exercise in three-dimensional conceptual gymnastics to compare multiple sections from several individuals and find equivalent regions of anatomy. Therefore, in comparing histology, one is very frequently left with an ambiguity as to whether differences in anatomical pattern or in fluorescence expression are really significant differences between individuals or whether they simply arise from the differences of location in the histological section across the different samples. Examining multiple individuals for both the control and manipulated group helps build confidence that differences, which are recognized multiple times, are likely to be real and systematic differences. However, if there is partial penetrance, ambiguity remains and can lead to even greater uncertainty.Thus it would be ideal, if it were possible, to obtain exactly equivalent microscopic slices of anatomy from groups of individuals that could be inspected side by side to identify with confidence any differences in anatomy or gene expression.2http://data.mouseimaging.ca/HREM/. Such high resolution and homogenous isotropic data should allow, in principle, the identification of equivalent sections through multiple individuals. However, to date, such data sets have only been analyzed visually by going back and forth between individuals and looking at multiple slices to try to find equivalent microscopic features (High-Resolution Episcopic Microscopy (HREM) gives three-dimensional isotropic images with excellent resolutions of 1–3 µm in all dimensions, as shown in features .Fig. 1TwThis communication shows how to use relatively standard three-dimensional image processing tools to find equivalent high resolution microscopic sections enabling direct visual comparison and statistical analysis of similarities and differences within and between groups of individuals. Furthermore, within homogenous groups, the recognition of consistent structures over multiple individuals allows for the possibility of annotating finer levels of reproducible anatomy.While this paper illustrates the method using mouse embryos, this ability to obtain homologous microscopic sections from multiple individuals should be of value for a variety of comparison tasks, at multiple stages of development, and in a variety of species.https://github.com/mouse-imaging-centre/pydpiper. Given the deformation fields required to bring each down-sampled individual HREM image into alignment with the average, the inverse fields are then used to back propagate any selected plane from the average three-dimensional image back into the individual HREM data, using linear interpolation to fill in intermediate points. Planes in any orientation can be selected for comparison. The interpolated deformation field is a best guess governed by the surrounding registration. The back propagated target plane, is then used to “cut” the original high resolution (3 µm) HREM data sets to yield homologous microscopic sections as shown in A schematic in As resolution becomes finer, even in genetically identical groups of individuals, the concept of homologous anatomical regions eventually breaks down. This can be recognized in images of the vasculature which have similarities of general pattern in multiple individuals, but there is no possibility, beyond several branching levels, to identify points that are equivalent to each other in terms of spatial anatomy. The small vessel arborized vascular tree is essentially stochastic. Thus, detailed microscopic sections taken as close as possible through homologous regions allow one to identify anatomical patterns that are consistent over multiple individuals in a group and conversely, to also recognize parts of anatomy for which the patterning is essentially stochastic. Conventional published atlases are annotated on the basis of recognizing the same structure in microscopic sections of multiple individuals. However, where the anatomical patterning has become stochastic, specific names are no longer assigned.Beyond simple visual observation, the deformation fields and the associated Jacobians can be used to highlight statistically significant variation between groups of embryos as illustrated in The combination of three-dimensional isotropic data obtained with HREM with comparatively straight forward image processing techniques for registration of down-sampled images allow for the identification of homologous microscopic sections from multiple different individuals. This, in turn, enables direct visual comparison and various statistical analyses of anatomical sections at a microscopic resolution. Whether differences in anatomy between groups of individuals are identified by computer analysis techniques or just by visual observation, these methods allow for detailed microscopic comparison among many specimens at a cellular level with minimal spatial ambiguity.


Pets can provide older adults a means of social support, which can combat problems faced in later life including loneliness, anxiety, and depression. However, current research findings in this area are mixed. The current study explored the differences in anxiety and depression between pet owners and non-pet owners and how pet ownership was associated with these symptoms after accounting for other established correlates. We hypothesized pet owners would endorse fewer symptoms of anxiety and depression than non-pet owners and owning a pet would be associated with these symptoms even after accounting for other common correlates. Participants included 608 older adults aged 70 to 95 that were included in the University of Alabama at Birmingham Study of Aging. As hypothesized, results indicated that pet owners endorsed significantly fewer symptoms of anxiety and depression than non-pet owners. Hierarchical regressions indicated that owning a pet explained a significant amount of variance in anxiety symptoms even after controlling for depression, self-reported health, and demographics. However, owning a pet did not have a significant association with depressive symptoms after accounting for anxiety, self-reported health, and demographics. These results suggest that lower rates of anxiety and depression are related to owning a pet and that pet ownership is associated with fewer anxiety symptoms, but not depressive symptoms, independent of several established correlates of anxiety. Future research is needed to determine the specific mechanisms of pet ownership that comprise this relationship as well as whether pet ownership may longitudinally reduce or buffer against anxiety in late life.


Along with rapid global population aging, the age-related cognitive disorders such as mild cognitive impairment (MCI) and dementia have posed a serious threat to public health, health care system, and sustainable economic and societal development of all countries. In this narrative review, we seek to summarize the major epidemiological studies from the life-course perspective that investigate the influence of genetic susceptibility  and intellectual or psychosocial factors  as well as their interactions on cognitive phenotypes in aging. Numerous population-based studies have suggested that early-life educational attainments and socioeconomic status, midlife work complexity and social engagements, late-life leisure activities , certain personality traits , and depression significantly affect late-life cognitive phenotypes. Furthermore, certain intellectual or psychosocial factors  may interact with genetic susceptibility  to affect the phenotypes of cognitive aging such that risk or beneficial effects of these factors on cognitive function may vary by carrying the susceptibility genes. Current evidence from the randomized controlled trials that support the cognitive benefits of cognitive training among cognitive healthy older adults remains limited. The cognitive reserve hypothesis has been proposed to partly explain the beneficial effects of lifetime intellectual and psychosocial factors on late-life cognitive function. This implies that, from a life-course perspective, preventive intervention strategies targeting multiple modifiable intellectual and psychosocial factors could interfere with clinical expression of cognitive disorders in old age and delay the onset of dementia syndrome, and thus, may help achieve healthy brain aging. Cognitive aging can be referred to as a process of gradual deteriorations in cognitive function that occur as people age. Phenotypes of cognitive aging as a continuum range from normal age-related cognitive decline through mild cognitive impairment (MCI) to a full stage of dementia; Alzheimer’s disease is the most common form of dementia among older people. The global aging population has increased steadily, especially in low- and middle-income countries such as China and India  to be relevant for determining the risk of chronic diseases  occurring later in life  and the onset of the first clinical symptoms of dementia  ε4 allele is so far the only established genetic factor for sporadic Alzheimer’s disease. The onset age of Alzheimer’s disease is decreased by about 3–4 years for people who carry every APOE ε4 allele  gene, cholesterol 24-hydroxylase gene, fat and obesity-associated FTO gene, and insulin degrading enzyme (IDE) gene  showed that occupational cognitive complexity earlier in adulthood was associated with better white-matter integrity and performance in processing speed and executive function in midlife  from young adulthood through midlife and old age is associated with a lower risk of dementia, as summarized and concluded in several systematic reviews  were associated with higher cognitive function and a reduced risk of dementia in late-life  to affect late-life cognitive phenotypes, i.e., the effects of these factors on cognitive phenotypes in aging may vary by genetic susceptibility. For example, several studies have shown that APOE ε4 allele may magnify the risk of dementia and cognitive impairment associated with midlife psychosocial factors such as physical inactivity and cognitive inactivity, such that people with these factors are more vulnerable to dementia and cognitive decline when carrying the ε4 allele , in which genetic susceptibility may play a part . The conThe underlying neural mechanisms for cognitive reserve are not fully understood. Neural reserve and neural compensation mechanisms have been proposed for cognitive reserve Stern, . Neural Along with rapid global population aging, cognitive impairment and dementia as the major cognitive disorders in aging have posed tremendous economic and societal burden to the modern societies. Epidemiological research has from the life-course perspective provided sufficient evidence suggesting that intellectual factors over the lifespan such as early-life high education, midlife work complexity, and late-life socially-integrative lifestyles  may delay the clinical onset of cognitive disorders in aging by providing cognitive reserve, whereas depression or depressive symptoms may confer risk for adverse cognitive outcomes in old age, in which the beneficial or risky effects may vary by genetic susceptibility . In this regard, a potential implication of these findings in dementia prevention is to conduct multimodal interventions targeting those intellectual and psychosocial factors together with other modifiable risk factors . However, evidence from randomized controlled trials or intervention studies is still limited. Thus, one of the priorities in future dementia research should be given to testing effects of the multimodal intervention approaches in delaying cognitive decline and the clinical onset of dementia among different populations in the world. The global coordinated effort toward this goal is ongoing, stimulated by the Finnish FINGER multidomain intervention models  have posed a serious threat to global public health, health care system, and sustainable economic and societal development. In this narrative review, we summarize the major epidemiological studies from the life-course perspective that investigate the influence of genetic susceptibility  and intellectual or psychosocial factors  as well as their interactions on cognitive phenotypes in aging. Population-based studies have suggested that early-life educational attainments, midlife work complexity and social engagements, late-life social, physical, and mental activities, and certain personality traits may affect late-life cognitive phenotypes. Furthermore, certain intellectual or psychosocial factors may interact with genetic susceptibility to affect the phenotypes of cognitive aging such that risk or beneficial effects of these factors on cognitive function may vary by carrying the susceptibility genes. The cognitive reserve hypothesis may partly explain the beneficial effects of lifespan intellectual and psychosocial factors on late-life cognitive function. This implies that, from a life-course perspective, intervention strategies targeting modifiable intellectual or psychosocial factors could interfere with clinical expression of cognitive disorders in old age and delay dementia onset, and thus, may help achieve healthy brain aging and reduce the burden of dementia.CQ and YW contributed to conceptualization and structure of the manuscript, reviewed the literature, and wrote the initial version of the manuscript. YD and JL provided critical comments and revisions. All authors have read and approved the final version of 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.


Pulmonary sarcoidosis involves the deposition of granulomas within the lung. These granulomas may affect lung function and lead to pulmonary symptoms, pulmonary dysfunction, functional impairment, and worsening of quality of life. Corticosteroids are generally highly effective in resolving the granulomatous inflammation of sarcoidosis. However, despite the effectiveness of corticosteroids, many corticosteroid-responsive patients continue to experience significant problems because of the development of fibrosis from previously active or active smoldering granulomatous inflammation, inflammatory effects from sarcoidosis unrelated to granuloma deposition in lung tissue (parasarcoidosis syndromes), and the development of significant corticosteroid-related side effects. For these reasons, the decision to treat pulmonary sarcoidosis and endpoints to measure meaningful outcomes may extend beyond considerations of pulmonary granulomatous inflammation alone. In this article, we propose a conceptual framework to describe the mechanisms by which pulmonary sarcoidosis significantly impacts patients. This conceptual framework suggests that indications for the treatment of pulmonary sarcoidosis and endpoints to assess treatment depend on the specific mechanisms that are causing functional or quality-of-life impairment (or both) in patients with pulmonary sarcoidosis. We believe that these concepts are important to clinicians treating pulmonary sarcoidosis and to clinical researchers designing pulmonary sarcoidosis trials. The decision to treat pulmonary sarcoidosis is complex because (a) the disease may cause neither symptoms nor permanent organ damage2; (b) a small percentage of cases, maybe 10 to 20%, are progressive or cause fibrosis  or both3; (c) there are no reliable biomarkers to predict whether the natural course of pulmonary sarcoidosis will be benign or lead to severe impairment4; and (d) treatment of pulmonary sarcoidosis with corticosteroids and other therapies is associated with significant toxicity5. These issues force clinicians, clinical researchers, and pharma to carefully select appropriate pulmonary sarcoidosis patients who have the potential to receive impactful benefits from interventions and to select the appropriate methods to assess therapeutic responses. Clinical trial design for pulmonary sarcoidosis has been problematic, and major trials have been criticized as not adequately accounting for the natural history of the disease in order to determine the benefits of study drugs6. This article will explore the indications for treatment of pulmonary sarcoidosis and methods to assess the effects of therapy. This exercise will involve the construction of a proposed conceptual framework outlining how pulmonary sarcoidosis leads to outcomes that are clinically impactful to patients or clinicians or both. This conceptual framework will suggest that patients in pulmonary sarcoidosis trials require partitioning into disease profiles that each require distinct clinical endpoints to optimally assess the effects of therapy.Sarcoidosis is a multisystem granulomatous disease of unknown cause. Granulomas consist of conglomerations of inflammatory cells, predominantly lymphocytes and macrophages. In sarcoidosis, these granulomas may deposit in any organ but most commonly develop within the lung, where they are found in more than 90% of sarcoidosis cases7.Because sarcoidosis may affect any organ in the body and its severity is highly variable, it is problematic to define specific criteria for treatment. Most sarcoidosis clinicians agree with Athol Wells’s distillation of the treatment indications for sarcoidosis to just two: situations of danger and significant quality of life (QOL) impairment (“Wells’s law”)9. Interestingly, the treatment of most of these dangerous situations involves therapy other than anti-granulomatous therapy, although most clinicians and sarcoidosis drug trials focus on obliterating the sarcoid granuloma.Sarcoidosis is a systemic disease, and situations of danger are not confined to the lung. Cardiac sarcoidosis may cause sudden death, eye involvement may result in blindness, and neurosarcoidosis may result in coma and permanent neurologic impairment. In the case of pulmonary sarcoidosis, situations of danger develop in a minority of patients and are listed in10. Mechanisms proposed to be involved in the development of sarcoidosis-associated fibrosis include alveolar macrophage-induced fibrosis11, transition from a T helper 1 to T helper 2 signature12, transforming growth factor-beta13, upregulation of profibrotic genes that may “transmit” signals for fibrosis through the blood compartment14, and M2 polarization of alveolar macrophages15.The immunopathogenesis of fibrosis in sarcoidosis is not well understood. It is not known whether the fibrosis is triggered by profibrotic inflammatory events, by an inherent predisposition toward fibrosis in a subset of patients, or by an exaggerated wound-healing response to uncontrolled, chronic inflammation16. This conjecture is further supported anatomically through chest imaging studies17  positron emission tomography demonstrated significant pulmonary FDG uptake in 22 (85%) of 26 patients with fibrotic pulmonary sarcoidosis19. These data suggest that the granulomatous inflammation of sarcoidosis and the development of fibrosis often go hand in hand20. The amount of fibrosis that develops is variable, from negligent to copious amounts. As previously mentioned, a significant fibrotic response from the granulomatous inflammation of sarcoidosis occurs in, at most, only 20% of cases9. Herein lies a key dilemma in preventing the granulomatous-induced fibrosis of sarcoidosis: since there is no available biomarker to predict which 10 to 20% of patients with pulmonary sarcoidosis will develop significant fibrosis, does the clinician (a) treat all pulmonary sarcoidosis with anti-granulomatous therapy that will prevent the development of fibrosis in 10 to 20% but subject 80% to 90% to potential drug toxicities from corticosteroids and other medications or (b) withhold anti-granulomatous therapy that will result in serious complications in the 10 to 20% who develop fibrosis? Clearly, a reliable biomarker that can accurately predict the development of significant pulmonary fibrosis from sarcoidosis is an unmet need. Effective anti-fibrotic therapy would also be very useful for this form of sarcoidosis, although none is available at present.It is conjectured that the fibrosis in pulmonary sarcoidosis results from the granulomatous inflammation. This conjecture is supported histologically where the majority of the fibrosis from sarcoidosis develops within or around the granuloma, resulting in a “hyalinized granuloma”dies17  as well 21. One could argue that sarcoidosis therapy is used primarily to improve physiology or organ function impaired by granulomatous inflammation or to decrease the granuloma burden , but a critical examination of this issue suggests that this is not the case22. Sarcoidosis-induced granulomatous inflammation may not cause a significant physiologic derangement or result in a significant impairment of QOL23. A common clinical situation where this is the case is with asymptomatic bilateral hilar lymphadenopathy24. Even when the granulomatous inflammation of pulmonary sarcoidosis results in physiologic abnormalities, they are often minor25 and do not invariably lead to appreciable symptoms25. In addition, the correlation between pulmonary dysfunction and pulmonary symptoms is poor in pulmonary sarcoidosis27. Therefore, the presence of granulomatous inflammation or mild physiologic derangements from pulmonary sarcoidosis does not mandate anti-sarcoidosis therapy unless the patient’s QOL is significantly impaired or significant organ dysfunction occurs22.Because the dangerous situations associated with pulmonary sarcoidosis are not common, the more common of the two indications suggested by Wells’s law to treat pulmonary sarcoidosis is sarcoidosis-induced impairment of QOL. A survey of 1842 European patients with sarcoidosis found that QOL and functionality were judged as the most important disease outcomes29. In most instances, they work quickly and reliably. However, they are associated with a number of potential side effects that may impair QOL. These include weight gain, mood swings/psychological disturbances, diabetes, osteoporosis, hypertension, glaucoma, cataracts, edema, acne, increased skin and vascular fragility, and increased risk of infection. Corticosteroid therapy has been clearly linked to the development of significant toxicities in patients with sarcoidosis30. If the clinician focuses primarily on reducing the granuloma burden or improving physiology, a medication-induced impairment of QOL may be undetected such that the clinician assesses the patient as improved while the patient feels worse off. This scenario may be relatively common, as it has been shown that those receiving corticosteroids at three major university sarcoidosis clinics in the US had statistically and clinically significant reductions in health-related QOL (HRQOL) compared with sarcoidosis patients not receiving corticosteroids27, and those receiving more than 500 mg or prednisone equivalent per year had a statistically and clinically worse HRQOL than those on a lower total yearly dose31.QOL assessment in pulmonary sarcoidosis is also significantly impacted by the potential toxicity of therapy, particularly corticosteroids. Corticosteroids are the drug of choice for the treatment of pulmonary sarcoidosis32. The HRQOL status of a patient may be assessed informally through unstructured historical questioning. Such an assessment may be thorough and used to make treatment decisions, but in the reality of the current era of patient care where time is compressed, such a detailed evaluation rarely takes place22. For this reason, many have advocated that the assessment of HRQOL in patients with sarcoidosis be assessed by patient-reported outcome measures (PROs), which are patient-administered reports of how they function or feel about their health condition and the effects of therapy34. HRQOL PROs provide a quantitative assessment of QOL and functional status in order to assess potential therapeutic effects. In addition, HRQOL PROs may be performed outside of patient clinic visit time and even serially between visits to assess the effects of therapy. However, there are several limitations of using HRQOL PROs on which to base pulmonary sarcoidosis treatment decisions. First, although some sarcoidosis disease–specific PROs have been developed and validated37, most HRQOL PROs used in patients with sarcoidosis are derived from other disease cohorts. However, an HRQOL PRO derived from non-sarcoidosis cohorts may be used in sarcoidosis provided that there is no plausible rationale that patients with sarcoidosis would assess the trait being measured in a different way than the cohort in which the PRO was validated23. Second, although PROs can reliably assess HRQOL in large clinical cohorts, most PROs have inadequate resolution to be useful in individual patients. PROs developed with modern methodology, such as item response theory (IRT), may have adequate resolution to accurately assess HRQOL in individuals40. Finally, QOL and HRQOL are not synonymous, as many high-priority QOL issues do not pertain to a medical condition or its treatment. It is often problematic to distinguish HRQOL issues from non-health-related QOL issues using HRQOL PROs. Because of these concerns, the role of HRQOL PROs in determining treatment decisions for individual patients with pulmonary sarcoidosis has not been standardized. There is uniform agreement that the clinician should not make treatment decisions in isolation without some insight into the patient’s HRQOL status, preferences, goals, and wishes.The assessment of QOL in pulmonary sarcoidosis is problematic. HRQOL refers to the extent that the physical, social, mental/emotional, cognitive, or spiritual domains (or a combination of these) are affected by a medical condition or its treatment41, and they may be responsible for significant QOL and functional impairment. Examples of parasarcoidosis syndromes are erythema nodosum42, small fiber neuropathy43, fatigue syndromes44, pain syndromes45, cognitive decline46, and vitamin D dysregulation47. It has been postulated that these syndromes result from systemic release of mediators associated with the granulomatous inflammation of sarcoidosis48. Although these parasarcoidosis syndromes may not result in appreciable pulmonary symptoms, they may be the result of the granulomatous inflammation from pulmonary sarcoidosis. Parasarcoidosis syndromes may respond to anti-granulomatous therapy50, although the decision to use such therapy must weigh the benefits versus the side effects of treatment in relation to the impact of the parasarcoidosis syndrome22. However, the etiology of parasarcoidosis syndromes is probably more complex than simply a result of granulomatous inflammation, as there may be several non-granulomatous contributions to some of these disorders, such as pain, fatigue, and cognitive impairment syndromes related to the psychological impact of the presence of a chronic disease or decreased function/mobility or both52.Sarcoidosis may also cause symptoms or organ dysfunction that is not related to tissue deposition of granulomas or the development of fibrosis. These entities are collectively known as parasarcoidosis syndromesWe have proposed a conceptual framework of how pulmonary sarcoidosis impacts patients through the relationships of granulomatous inflammation, physiologic impairment, fibrosis, parasarcoidosis syndromes and the impact of anti-sarcoidosis therapy . This coThis conceptual framework is directed at immunologic and physiologic factors of pulmonary sarcoidosis that impact patient health. It reflects relevant issues concerning the evaluation of these drugs in clinical pulmonary sarcoidosis trials, including the establishment of study entry criteria and clinically relevant endpoints. However, issues concerning the management of patients with pulmonary sarcoidosis extend beyond these immunologic and physiologic factors. For example, psychosocial and socioeconomic concerns are important considerations of therapy. Such concerns include the cost of care, including medication costs, access to care, social support, employment issues, emotional and psychological issues, and ease in maintaining a healthy lifestyle.53. Obviously, anti-granulomatous therapy is a rational approach to the treatment of this condition. As depicted by the black arrows inAcute pulmonary sarcoidosis is a form of the disease that causes worsening pulmonary symptoms and dysfunction over weeks to months and is thought to result from the formation of new granulomas within the lung or growth of existing pulmonary granulomas58. However, as previously mentioned, because the granulomatous inflammation of sarcoidosis may not progress or even spontaneously resolve without therapy and therapy is associated with significant toxicity, treatment of acute pulmonary sarcoidosis also requires that the condition has resulted in a significant impairment of QOL.Obviously, patients with pulmonary sarcoidosis should be considered for anti-granulomatous therapy only if they have evidence of active granulomatous inflammation.59.The endpoints for the treatment of acute untreated pulmonary sarcoidosis should include all three of the following: (a) improvement/resolution of granulomatous inflammation, (b) improvement in pulmonary physiology, and (c) improvement in function status or QOL or both. The rationale for this is explained in60.61. For pulmonary sarcoidosis, these corticosteroid-sparing agents include anti-metabolites such as methotrexate63, azathioprine65, and the tumor necrosis factor-alpha (TNF-α) antagonists infliximab56 and adalimumab66. These agents usually are used as second- or third-line agents that are added on to corticosteroid therapy because they either take weeks to months longer than corticosteroids to be effective65 or—in the case of the TNF-α antagonists—are much more expensive than corticosteroids.Because corticosteroids are highly efficacious for pulmonary sarcoidosis, additional anti-granulomatous agents are often used as corticosteroid-sparing agents in order to lower the corticosteroid dose requirement. Additional agents can also be used to provide further anti-granulomatous therapy on top of corticosteroids, although often the additional benefit of such agents is minimal in pulmonary sarcoidosis patients receiving more than 10 to 15 mg of prednisone per day56.Entry criteria for anti-granulomatous therapy trials for patients with chronically treated pulmonary sarcoidosis should include evidence of granulomatous inflammation, physiologic impairment, and functional/QOL impairment at study entry or—if a corticosteroid withdrawal phase of the trial is planned—historical evidence of these abnormalities when the corticosteroid dose is lowered.For these reasons, the endpoints of trials for acute untreated pulmonary sarcoidosis are not highly relevant to evaluate anti-granulomatous drugs used in chronically treated pulmonary sarcoidosis patients. There is often little granulomatous inflammation left to treat, and the issue is whether the drug will continue to suppress granulomatous inflammation when the corticosteroid dose is lowered. The same could be said for the physiologic endpoint: the issue is often not whether the additional drug will improve pulmonary physiology but rather whether it will allow the pulmonary physiology to be maintained as the corticosteroid dose is lowered. The QOL endpoint is still highly relevant, especially in terms of a reduction of corticosteroid side effects.As previously mentioned, it is conjectured that the fibrosis in sarcoidosis is the result of granulomatous inflammation. The relationship of granulomatous inflammation, pulmonary fibrosis, and treatment of pulmonary sarcoidosis is depicted in68, bronchiectasis70, and pulmonary mycetoma72. The indications for treatment of these conditions as well as the endpoints to monitor these forms of disease are well covered elsewhere75. Anti-granulomatous therapy is rarely useful for sarcoidosis-associated pulmonary hypertension and is often detrimental for bronchiectasis and pulmonary mycetoma as it may cause serious infectious complications. As end-stage pulmonary fibrosis is a disabling and life-threatening condition, lung transplantation should be considered in fibrotic pulmonary sarcoidosis patients with limited chance for improvement and minimal extrapulmonary comorbidities76.Therapy for fibrotic pulmonary sarcoidosis is currently aimed at either (a) treating the complications of pulmonary fibrosis or (b) preventing the progression of further lung fibrosis. The complications of pulmonary fibrosis are listed in19. It is thought that such “smoldering” granulomatous inflammation is the nidus for the development of further fibrosis. Therefore, evidence of granulomatous inflammation would be a prerequisite for instituting anti-granulomatous therapy for fibrotic pulmonary sarcoidosis.In terms of therapy to prevent the development of further fibrosis, it has already been mentioned that the majority of patients with fibrotic pulmonary sarcoidosis have evidence of granulomatous inflammation79.An additional issue when considering treatment of sarcoidosis-associated pulmonary fibrosis is the rapidity of its development. It is thought that fibrosis develops slowly in pulmonary sarcoidosis, such that the cumulative toxicities of long-term anti-sarcoidosis medications, especially corticosteroids, would limit their long-term use. Certainly, evidence of rapid development of pulmonary fibrosis with a concomitant rapid decline in physiology or functional status/QOL would be a strong impetus to consider anti-granulomatous therapy. Because of the toxicity of corticosteroids and other anti-granulomatous therapies, another approach would be to use “downstream” medications targeting the development of fibrosis itself. Such medications include pirfenidone and nintedanib, which have been shown to decelerate the development of lung fibrosis in idiopathic pulmonary fibrosis and other interstitial lung diseases57. The ablation of granulomatous inflammation may improve QOL by reducing symptoms derived from parasarcoidosis syndromes that may be indirectly derived from granulomatous inflammation (see below). However, other useful endpoints for the treatment of fibrotic pulmonary sarcoidosis may reflect a lack of deterioration of patient status.In terms of endpoints for the treatment of fibrotic pulmonary sarcoidosis, improvements in pulmonary function and functional status/QOL from anti-granulomatous therapy may be significant yet are unlikely to be large because improvement in the patient’s pulmonary function is unlikely to be greatThe physiologic impairment resulting from the granulomatous inflammation of pulmonary sarcoidosis is highly variable. Even more variable is the effect of these physiologic derangements on the QOL of the patient with pulmonary sarcoidosis. This granulomatous inflammation can also adversely affect the QOL of the patient with sarcoidosis by systemic mechanisms other than direct deposition of granulomas into specific organs (“parasarcoidosis syndromes”). Additionally, this granulomatous inflammation may lead to the development of pulmonary fibrosis that causes irreversible pulmonary dysfunction and, potentially, disabling and life-threatening situations. Finally, anti-granulomatous therapy not only may improve the QOL of the patient with pulmonary sarcoidosis by effectively treating the disease but also may worsen it by causing serious drug side effects. We have proposed a conceptual framework to outline how these many factors interact to cause physiologic and QOL impairments in pulmonary sarcoidosis. We believe that this conceptual framework may be useful in constructing a clinical drug trial for pulmonary sarcoidosis that reflects the concerns of patients and clinicians.Because of numerous aspects of pulmonary sarcoidosis and its therapy, it is not surprising that developing treatment indications and endpoints for the therapy of the disease is challenging. We have made a case for partitioning patients into three treatment groups when considering indications for therapy as well as therapy endpoints: untreated patients with active granulomatous inflammation, patients with chronically treated disease, and those with significant lung fibrosis. It is hoped that this proposed patient partitioning will stimulate debate and constructive criticism that will eventually lead to therapy for pulmonary sarcoidosis that is better directed in treating the true concerns of patients.


Known for sterile inflammation, MCs play a critical role in neuroinflammation, which is facilitated by their close proximity to nerve fibers in the periphery and meninges of the spinal cord and the brain. Multifaceted activation of MCs releasing neuropeptides, cytokines and other mediators has direct effects on the neural system as well as neurovascular interactions. Emerging studies have identified the release of extracellular traps, a phenomenon traditionally meant to ensnare invading pathogens, as a cause of MC-induced neural injury. In this review article, we will discuss mechanisms of MC interaction with the nervous system through degranulation,  Noxious (toxic or injurious) substances released include but are not limited to histamine  are proinflammatory cells that are the first responders of the immune system  and rearrangement of F-actin and microtubule formation. FcεR1 activates Fyn/Gab2/RhoA tyrosine kinases and leads to microtubule polymerization and the shuttling of secretory granules to the plasma membrane . TyrosinIn the bladder, bidirectional communication between nerves and MCs using lamellipodia that enclosed fibers within a cell have been observed  receptors are involved in mediating response in cooperation with the toll-like receptor (TLR). TLRs also recruit CD14 or CD48 for the effect of TLR ligands , which is a receptor tyrosine kinase for stem cell factor  release is common to many different cells. EVs may be formed in endosomes and released through exocytosis. MC exosomes are known to interact with sensory nerves through the release of SP , which are F-actin structures that form in response to reticulation. TNTs are similar to pseudopodia described earlier, except they are not adherent, and can span distances longer than pseudopodia. MC-microglia interactions have been found to be involved in brain inflammation  formation is dependent on reactive oxygen species (ROS) formation and engagement of TLR4 . In addiIt is well documented that MC mediators contribute to endothelial dysfunction in the vasculature , respectively on MCs. Receptors were inhibited by methoxyluteolin inhibiting IL33 decreased IL-1β release  have been known to activate MCs (Taracanova et al., MCs have been found to increase vascular permeability in the skin of mice with sickle cell disease (SCD; Vincent et al., via corticotropin-releasing hormone (Esposito et al., via neurovascular interactions.Increased vascular permeability has been found in the CNS where MC degranulation compromises the BBB and allows further entry of inflammatory substances into the brain (Zhuang et al., via diverse mechanisms alters the microenvironment leading to a hypersensitized system. Recent advances in MC-CNS interactions demonstrate that MC-induced hypersensitivity also contributes to the CNS disorders and pain. Thus, targeting of MCs provides a potentially treatable target for the disorders of the CNS and pain.MCs contribute to neural and vascular injury directly as well as induce neurovascular interactions. The complex milieu of multiple mediators released from MCs AM wrote the manuscript and prepared for submission. VS edited the manuscript. MG wrote and edited the manuscript. KG conceived, designed, and supervised the manuscript writing and editing and prepared the figure.KG is a Consultant for Tau Tona Group and Novartis but it does not have conflict with the present work. The remaining 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.