Microbiota metabolites modulate the T helper 17 to regulatory T cell (Th17/Treg) imbalance promoting resilience to stress-induced anxiety- and depressive-like behaviors

The alterations in CD4+Treg cells across various phases of major depression

BACKGROUND

Major depression (MD) is recurrent and devastating mental disease with a high worldwide prevalence. Mounting evidence suggests neuroinflammation triggers cellular immune dysregulation, characterized by increased proportions of circulating monocytes, and T helper 17 cells and proinflammatory cytokines, thereby increasing susceptibility to MD. However, there is ambiguity in the findings of clinical studies that investigate CD4+ T regulatory (Treg) cells in MD.

METHODS

The proportion of CD4+ Treg cell from blood mononuclear cells was examined using flow cytometry in healthy controls (HCs: n = 96) and patients with first (FEMD: n = 62) or recurrent (RMD: n = 41) disease episodes of MD at baseline (T0; hospital admission) and after a two-week antidepressant treatment (T14). All participants underwent comprehensive neuropsychological assessments.

RESULTS

The initial scores on emotional assessments in patients with MD significantly differed from those of HCs. Both FEMD and RMD patients exhibited a significant decrease in CD4+ Treg cell proportion at baseline compared to HCs. Treg cell proportion rose significantly from T0 to T14 in FEMD patients, who responded to antidepressant therapy, whereas no significant changes were observed in FEMD patients in non-response as well as RMD patients. The improvement of 24-item Hamilton Depression Scale was correlate with changes of Treg cell proportion from T0 to T14 in FEMD patients in response, and the change in Treg cell proportion over a 14-day period exhibited an AUC curve of 0.710.

CONCLUSIONS

A decrease in the proportion of CD4+ Treg cells points towards immune system abnormalities in patients with MD. Furthermore, our finding suggests that the immune activation state varies across different stages of depression.

Synbiotic therapy with Clostridium sporogenes and xylan promotes gut-derived indole-3-propionic acid and improves cognitive impairments in an Alzheimer's disease mouse model

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized primarily by cognitive impairment. Recent investigations have highlighted the potential of nutritional interventions that target the gut-brain axis, such as probiotics and prebiotics, in forestalling the onset of AD. In this study, whole-genome sequencing was employed to identify xylan as the optimal carbon source for the tryptophan metabolism regulating probiotic Clostridium sporogenes (C. sporogenes). Subsequent in vivo studies demonstrated that administration of a synbiotic formulation comprising C. sporogenes (1 × 1010 CFU per day) and xylan (1%, w/w) over a duration of 30 days markedly enhanced cognitive performance and spatial memory faculties in the 5xFAD transgenic AD mouse model. The synbiotic treatment significantly reduced amyloid-β (Aβ) accumulation in the cortex and hippocampus of the brain. Importantly, synbiotic therapy substantially restored the synaptic ultrastructure in AD mice and suppressed neuroinflammatory responses. Moreover, the intervention escalated levels of the microbial metabolite indole-3-propionic acid (IPA) and augmented the relative prevalence of IPA-synthesizing bacteria, Lachnospira and Clostridium, while reducing the dominant bacteria in AD, such as Aquabacterium, Corynebacterium, and Romboutsia. Notably, synbiotic treatment also prevented the disruption of gut barrier integrity. Correlation analysis indicated a strong positive association between gut microbiota-generated IPA levels and behavioral changes. In conclusion, this study demonstrates that synbiotic supplementation significantly improves cognitive and intellectual deficits in 5xFAD mice, which could be partly attributed to enhanced IPA production by gut microbiota. These findings provide a theoretical basis for considering synbiotic therapy as a novel microbiota-targeted approach for the treatment of metabolic and neurodegenerative diseases.

Baseline gut microbiota profiles affect treatment response in patients with depression

The role of the gut microbiota in the pathophysiology of depression has been explored in numerous studies, which have confirmed that the baseline gut microbial profiles of patients with depression differ from those of healthy individuals. The gut microbiome affects metabolic activity in the immune and central nervous systems and regulates intestinal ecology through the neuroendocrine system. Additionally, baseline changes in the gut microbiota differed among patients with depression who demonstrated varying treatment response. Currently, probiotics are an emerging treatment for depression; however, the efficacy of modulating the gut microbiota in the treatment of depression remains uncertain. Additionally, the mechanisms by which changes in the gut microbiota affect treatment response in patients with depression remain unclear. In this review, we aimed to summarize the differences in the baseline gut microbiota between the remission and non-remission groups after antidepressant therapy. Additionally, we summarized the possible mechanisms that may contribute to antidepressant resistance through the effects of the gut microbiome on the immune and nervous systems, various enzymes, bioaccumulation, and blood-brain barrier, and provide a basis for treating depression by targeting the gut microbiota.

Recognizing depression as an inflammatory disease: the search for endotypes

Major depressive disorder (MDD) affects millions of individuals worldwide, leading to considerable social and economic costs. Despite advancements in pharmacological treatments, achieving remission remains a key challenge, with a substantial number of patients showing resistance to existing therapies. This resistance is often associated with elevated levels of proinflammatory cytokines, suggesting a connection between inflammation, MDD pathophysiology, and treatment efficacy. The observation of increased immune activation in about a quarter of patients with MDD resulted in the distinction between inflammatory and noninflammatory endotypes. Although anti-inflammatory treatments show promise in alleviating depression-like symptoms, responses are heterogeneous, thus highlighting the importance of identifying distinct inflammatory endotypes to tailor effective therapeutic strategies. The intestinal microbiome emerges as a crucial modulator of mental health, mediating its effects partially through different immune pathways. Microbiota-derived short-chain fatty acids (SCFAs) significantly impact innate and adaptive immune cells, regulating their differentiation, function, and cellular response. Furthermore, gut-educated immune cells reach the border regions of the central nervous system (CNS), regulating glial cell functions. Although the CNS modulates immune responses via efferent parts of the vagus nerve, afferent tracts concurrently transport information on peripheral inflammation back to the brain. This bidirectional communication is particularly relevant in depression, allowing for therapeutic stimulation of the vagus nerve in the context of inflammatory depression endotypes. In this review, we explore the intricate relationship between inflammation and depression, discuss how inflammatory signals are translated into depressive-like symptoms, and highlight immune-modulating therapeutic avenues.

The dual roles of serotonin in antitumor immunity

Research has shown that a significant portion of cancer patients experience depressive symptoms, often accompanied by neuroendocrine hormone imbalances. Depression is frequently associated with decreased levels of serotonin with the alternate name 5-hydroxytryptamine (5-HT), leading to the common use of selective serotonin reuptake inhibitors (SSRIs) as antidepressants. However, the role of serotonin in tumor regulation remains unclear, with its expression levels displaying varied effects across different types of tumors. Tumor initiation and progression are closely intertwined with the immune function of the human body. Neuroimmunity, as an interdisciplinary subject, has played a unique role in the study of the relationship between psychosocial factors and tumors and their mechanisms in recent years. This article offers a comprehensive review of serotonin's regulatory roles in tumor onset and progression, as well as its impacts on immune cells in the tumor microenvironment. The aim is to stimulate further interdisciplinary research and discover novel targets for tumor treatment.

Integrated Single-Cell RNA-seq and ATAC-seq Reveals Heterogeneous Differentiation of CD4+ Naive T Cell Subsets is Associated with Response to Antidepressant Treatment in Major Depressive Disorder

The mechanism involved in major depressive disorder (MDD) is well-studied but the mechanistic origin of the heterogeneous antidepressant effect remains largely unknown. Single-cell RNA-sequencing (scRNA-seq) and assay for transposase-accessible chromatin using sequencing (ATAC-seq) on peripheral blood mononuclear cells from 8 healthy individuals and 8 MDD patients before or after 12 weeks of antidepressant treatment is performed. scRNA-seq analysis reveals a lower proportion of naive T cells, particularly CD4+ naive T cells, in MDD patients compared to controls, and in nonresponders versus responders at the baseline. Flow cytometry data analysis of an independent cohort of 35 patients and 40 healthy individuals confirms the findings. Enrichment analysis of differentially expressed genes indicated obvious immune activation in responders. A specific activated CD4+ naive T population in responders characterized by enhanced mitogen-activated protein kinases (MAPK) pathway is identified. E-twenty six (ETS) is proposed as an upstream regulator of the MAPK pathway and heterogeneous differentiation in activated CD4+ naive T population is associated with the response to antidepressant treatment in MDD patients. A distinct immune feature manifested by CD4+ naive T cells during antidepressant treatment in MDD is identified. Collectively, this proposes the molecular mechanism that underlies the heterogeneous antidepressant outcomes for MDD.

Generalized Pustular Psoriasis and Systemic Organ Dysfunctions

This review explores the intricate relationship between generalized pustular psoriasis (GPP) and various systemic diseases, shedding light on the broader impacts of this severe skin condition beyond its primary dermatological manifestations. GPP is identified as not only a profound contributor to skin pathology but also a significant risk factor for systemic diseases affecting cardiovascular, hepatic, renal, pulmonary, and skeletal systems, as well as associated with an increased incidence of anemia, depression, anxiety, and arthritis. The research highlights the complex interplay of cytokines, particularly IL-17 and IL-36, which are central to the pathophysiology of GPP and implicated in the exacerbation of systemic conditions. Key findings indicate a higher incidence of cardiovascular events in GPP patients compared to those with other severe forms of psoriasis, notably with a stronger correlation between myocardial infarction history and GPP development. Liver disturbances, frequently reversible upon psoriasis remission, suggest a cytokine-mediated link to hepatic health. Renal dysfunction appears elevated in GPP sufferers, with IL-17 and IL-36 potentially driving renal fibrosis. Similarly, interstitial lung disease and osteoporosis in GPP patients underscore the systemic reach of inflammatory processes initiated in the skin. The associations with anemia, depression, anxiety, and arthritis further complicate the clinical management of GPP, requiring a multidisciplinary approach. The study concludes that managing GPP effectively requires a holistic approach that addresses both the cutaneous and systemic dimensions of the disease, advocating for continued research into the mechanisms that connect GPP with broader health implications to refine therapeutic strategies.

Inflammatory biomarkers and perinatal depression: A systematic review

BACKGROUND

Approximately 10 to 20% of pregnant women worldwide experience perinatal depression (PND), a depressive episode with onset during pregnancy or after childbirth. We performed a systematic review to identify, summarize and discuss studies on inflammatory biomarkers described in relation to PND.

METHOD

Inclusion criteria defined the selection of observational studies written in English, French, Spanish or Portuguese, that evaluate analytical levels of inflammatory molecules (protein levels) in biological fluids in women, with a diagnosis of depression using ICD/DSM diagnostic criteria or depressive symptoms assessed by standardized psychometric instruments, during pregnancy and/or postpartum. Case reports, experimental studies, reviews, qualitative analysis, meta-analysis, gray literature or replicated data were excluded. Three electronic databases were used for search (Pubmed, Web of Science and PsychInfo) and quality assessment of selected studies were performed using the Newcastle-Ottawa Scale. Data extraction included study design; number of subjects; obstetric information; tools and timepoints of depression and inflammatory markers assessment.

RESULTS

56 studies (sample size for cross-sectional and case-control studies ranging from 10 to 469; sample size for longitudinal studies ranging from 26 to 467), where the major aim was to analyze the association between depression and inflammatory biomarkers during pregnancy and postpartum period were included in this systematic review. Overall, the findings of our systematic review lend support to the hypothesis that several inflammatory markers may be associated with peripartum depressive symptoms. The associations were somewhat different looking at pregnancy compared to the delivery time-point and postpartum, and mainly referred to increased levels of IL-6, IL-8, CRP and TNF-α among depressed.

DISCUSSION

In summary, our systematic review findings provide evidence supporting the hypothesis that several inflammatory markers may correlate with peripartum depressive symptoms. However, our work also highlighted notable differences in the timing of biological sampling for inflammatory markers and in the methodologies used to assess depression during the perinatal period. Additionally, variations were observed in how inflammatory biomarkers and depression were approached, including their classification as exposure or outcome variables, and the timing of assessments. It is essential for future research to investigate the influence of biological fluids and the timing of assessments for both inflammatory biomarkers and depression to gain a deeper understanding of their association. This comprehensive exploration is pivotal for elucidating the intricate relationship between inflammation and perinatal depression.

Dietary (Poly)phenols and the Gut-Brain Axis in Ageing

As the population ages, the incidence of age-related neurodegenerative diseases is rapidly increasing, and novel approaches to mitigate this soaring prevalence are sorely needed. Recent studies have highlighted the importance of gut microbial homeostasis and its impact on brain functions, commonly referred to as the gut-brain axis, in maintaining overall health and wellbeing. Nonetheless, the mechanisms by which this system acts remains poorly defined. In this review, we will explore how (poly)phenols, a class of natural compounds found in many plant-based foods and beverages, can modulate the gut-brain axis, and thereby promote neural health. While evidence indicates a beneficial role of (poly)phenol consumption as part of a balanced diet, human studies are scarce and mechanistic insight is still lacking. In this regard, we make the case that dietary (poly)phenols should be further explored to establish their therapeutic efficacy on brain health through modulation of the gut-brain axis, with much greater emphasis on carefully designed human interventions.

Adolescent male rats show altered gut microbiota composition associated with depressive-like behavior after chronic unpredictable mild stress: Differences from adult rats

Accumulating evidence reveals the metabolism and neurotransmitter systems are different in major depressive disorder (MDD) between adolescent and adult patients; however, much is still unknown from the gut microbiome perspective. To minimize confounding factors such as geographical location, ethnicity, diet, and drugs, we investigated the gut microbial differences between adolescent and adult male Sprague-Dawley rats. We exposed the adolescent rats to chronic unpredictable mild stress (CUMS) for 3 weeks and assessed their behavior using the sucrose preference test (SPT), open field test (OFT), and forced swimming test (FST). We collected and sequenced fecal samples after the behavioral tests and compared them with our previous data on adult rats. Both adolescent and adult CUMS rats exhibited reduced sucrose preference in SPT, reduced total distance in OFT, and increased immobility time in FST. Moreover, compared to their respective controls, the adolescent CUMS rats had distinct amplicon sequence variants (ASVs) mainly in the Muribaculaceae family, Bacteroidetes phylum, while the adult CUMS rats had those in the Lachnospiraceae family, Firmicutes phylum. In the adolescent group, the Muribaculaceae negatively correlated with FST and positively correlated with SPT and OFT. In the adult group, the different genera in the Lachnospiraceae showed opposite correlations with FST. Furthermore, the adolescent CUMS rats showed disrupted microbial functions, such as "Xenobiotics biodegradation and metabolism" and "Immune system", while the adult CUMS rats did not. These results confirmed the gut microbiota differences between adolescent and adult rats after CUMS modeling and provided new insight into the age-related influence on depression models.

Immunotherapy for depression: Recent insights and future targets

Depression stands as a prominent contributor to global disability, entailing an elevated risk of suicide. Substantial evidence supports the notion that immune dysregulation may play a role in the development of depression and impede responses to antidepressant treatments. Immune dysregulation may cause depression in susceptible individuals through raising inflammatory responses. Differences in immune cell types and the release of pro-inflammatory mediators are observed in the blood and cerebrospinal fluid of patients with major depressive disorder, which is associated with neuroimmune dysfunction. Therefore, the interaction of peripheral and central immune targets in depression needs to be understood. Urgent attention is required for the development of innovative therapeutics directed at modulating immune responses for the treatment of depression. This review delineates the immune mechanisms involved in the pathogenesis of depression, assesses the therapeutic potential of immune system targeting for depression treatment, and deliberates on the merits and constraints of employing immunotherapy in the management of depression.

Hormetic Nutrition and Redox Regulation in Gut-Brain Axis Disorders

The antioxidant and anti-inflammatory effects of hormetic nutrition for enhancing stress resilience and overall human health have received much attention. Recently, the gut-brain axis has attracted prominent interest for preventing and therapeutically impacting neuropathologies and gastrointestinal diseases. Polyphenols and polyphenol-combined nanoparticles in synergy with probiotics have shown to improve gut bioavailability and blood-brain barrier (BBB) permeability, thus inhibiting the oxidative stress, metabolic dysfunction and inflammation linked to gut dysbiosis and ultimately the onset and progression of central nervous system (CNS) disorders. In accordance with hormesis, polyphenols display biphasic dose-response effects by activating at a low dose the Nrf2 pathway resulting in the upregulation of antioxidant vitagenes, as in the case of heme oxygenase-1 upregulated by hidrox® or curcumin and sirtuin-1 activated by resveratrol to inhibit reactive oxygen species (ROS) overproduction, microbiota dysfunction and neurotoxic damage. Importantly, modulation of the composition and function of the gut microbiota through polyphenols and/or probiotics enhances the abundance of beneficial bacteria and can prevent and treat Alzheimer's disease and other neurological disorders. Interestingly, dysregulation of the Nrf2 pathway in the gut and the brain can exacerbate selective susceptibility under neuroinflammatory conditions to CNS disorders due to the high vulnerability of vagal sensory neurons to oxidative stress. Herein, we aimed to discuss hormetic nutrients, including polyphenols and/or probiotics, targeting the Nrf2 pathway and vitagenes for the development of promising neuroprotective and therapeutic strategies to suppress oxidative stress, inflammation and microbiota deregulation, and consequently improve cognitive performance and brain health. In this review, we also explore interactions of the gut-brain axis based on sophisticated and cutting-edge technologies for novel anti-neuroinflammatory approaches and personalized nutritional therapies.

Stress increases hepatic release of lipocalin 2 which contributes to anxiety-like behavior in mice

Chronic stress induces anxiety disorders via both neural pathways and circulating factors. Although many studies have elucidated the neural circuits involved in stress-coping behaviors, the origin and regulatory mechanism of peripheral cytokines in behavioural regulation under stress conditions are not fully understood. Here, we identified a serum cytokine, lipocalin 2 (LCN2), that was upregulated in participants with anxiety disorders. Using a mouse model of chronic restraint stress (CRS), circulating LCN2 was found to be related to stress-induced anxiety-like behaviour via modulation of neural activity in the medial prefrontal cortex (mPFC). These results suggest that stress increases hepatic LCN2 via a neural pathway, leading to disrupted cortical functions and behaviour.

Guillain-Barré syndrome after surgery: a literature review

Guillain-Barré syndrome (GBS) is a rare postoperative complication that is sometimes characterized by serious motor weakness and prolonged weaning from mechanical ventilation. Although the exact nature of the relationship between GBS and the surgical procedure is still unclear, there is a clear increased incidence of GBS in post-surgical patients compared to non-surgical patients. GBS after surgery is unique in several ways. The course of post-surgical GBS unfolds more rapidly than in other situations where GBS develops, the condition is often more severe, and respiratory muscles are more commonly involved. Prompt diagnosis and appropriate treatment are essential, and the condition can worsen if treated inappropriately. Postoperative sedation, intubation, and restraint use make the diagnosis of GBS difficult, as the onset of symptoms of weakness or numbness in those contexts are not obvious. GBS is often misdiagnosed, being attributed to other postoperative complications, and subsequently mishandled. The lack of relevant information further obscures the clinical picture. We sought to better understand post-surgical GBS by performing an analysis of the relevant literature, focusing on clearly documenting the clinical characteristics, diagnosis, and management of GBS that emerges following surgery. We underscore the importance of physicians being aware of the possibility of GBS after major surgery and of performing a variety of laboratory clinical investigations early on in suspected cases.

Decoding and reconstructing disease relations between dry eye and depression: a multimodal investigation comprising meta-analysis, genetic pathways and Mendelian randomization

INTRODUCTION

The clinical presentations of dry eye disease (DED) and depression (DEP) often comanifest. However, the robustness and the mechanisms underlying this association were undetermined.

OBJECTIVES

To this end, we set up a three-segment study that employed multimodality results (meta-analysis, genome-wide association study [GWAS] and Mendelian randomization [MR]) to elucidate the association, common pathways and causality between DED and DEP.

METHODS

A meta-analysis comprising 26 case-control studies was first conducted to confirm the DED-DEP association. Next, we performed a linkage disequilibrium (LD)-adjusted GWAS and targeted phenotype association study (PheWAS) in East Asian TW Biobank (TWB) and European UK Biobank (UKB) populations. Single-nucleotide polymorphisms (SNPs) were further screened for molecular interactions and common pathways at the functional gene level. To further elucidate the activated pathways in DED and DEP, a systemic transcriptome review was conducted on RNA sequencing samples from the Gene Expression Omnibus. Finally, 48 MR experiments were implemented to examine the bidirectional causation between DED and DEP.

RESULTS

Our meta-analysis showed that DED patients are associated with an increased DEP prevalence (OR = 1.83), while DEP patients have a concurrent higher risk of DED (OR = 2.34). Notably, cross-disease GWAS analysis revealed that similar genetic architecture (rG = 0.19) and pleiotropic functional genes contributed to phenotypes in both diseases. Through protein-protein interaction and ontology convergence, we summarized the pleiotropic functional genes under the ontology of immune activation, which was further validated by a transcriptome systemic review. Importantly, the inverse variance-weighted (IVW)-MR experiments in both TWB and UKB populations (p value <0.001) supported the bidirectional exposure-outcome causation for DED-to-DEP and DEP-to-DED. Despite stringent LD-corrected instrumental variable re-selection, the bidirectional causation between DED and DEP remained.

CONCLUSION

With the multi-modal evidence combined, we consolidated the association and causation between DED and DEP.

Effects of exercise therapy on anxiety and depression in patients with COVID-19: a systematic review and meta-analysis

Objective

With increasing rates of anxiety and depression during COVID-19, exercise treatment has drawn attention for its effects on COVID-19 patients with anxiety and depression. This study set out to assess the impact of exercise therapy on COVID-19 patients' anxiety and depression.

Methods

PubMed, EMBASE, Web of Science and Cochrane Library were used to search articles about exercise therapy as a means of treating anxiety and depression in COVID-19 patients from inception to April 30, 2023. The risk of bias was assessed by the Cochrane Collaboration bias risk tool. Data were pooled with the random effects model. RevMan version 5.4 was used for the statistical analyses. This work was registered in the PROSPERO database (registration number: CRD42023406439).

Selection criteria

Randomized clinical trials (RCTs) of COVID-19 patients with anxiety and depression were included to assess the impact of physical exercise on COVID-19 patients with anxiety and depression.

Results

6 studies including a total of 461 COVID-19 patients were analyzed in this meta-analysis. Overall, the meta-analysis showed that compared with the control group, exercise could significantly improve anxiety (SMD = -0.76; 95%CI: -0.96, -0.55; p < 0.00001), depression level (SMD = -0.39; 95%CI: -0.70, -0.09; p = 0.01), the PHQ-9 score (MD = -1.82; 95%CI: -2.93, -0.71; p = 0.001) and the sleep quality (SMD = -0.73; 95%CI: -1.32, -0.14; p = 0.01) in COVID-19 patients.

Conclusion

The research provided evidence that exercise therapy is able to help COVID-19 patients experience less anxiety and depression and have better-quality sleep.

Systematic review registration

CRD42023406439.

Gut microbiome promotes mice recovery from stress-induced depression by rescuing hippocampal neurogenesis

Studies from rodents to primates and humans indicate that individuals vary in how resilient they are to stress, and understanding the basis of these variations may help improve treatments for depression. Here we explored the potential contribution of the gut microbiome to such variation. Mice were exposed to chronic unpredictable mild stress (CUMS) for 4 weeks then allowed to recover for 3 weeks, after which they were subjected to behavioral tests and categorized as showing low or high stress resilience. The two types of mouse were compared in terms of hippocampal gene expression using RNA sequencing, fecal microbiomes using 16S RNA sequencing, and extent of neurogenesis in the hippocampus using immunostaining of brain sections. Fecal microbiota were transplanted from either type of mouse into previously stress-exposed and stress-naïve animals, and the effects of the transplantation on stress-induced behaviors and neurogenesis in the hippocampus were examined. Finally, we blocked neurogenesis using temozolomide to explore the role of neurogenesis promoted by fecal microbiota transplantation in enhancing resilience to stress. Results showed that highly stress-resilient mice, but not those with low resilience, improved significantly on measures of anhedonia, behavioral despair, and anxiety after 3-week recovery from CUMS. Their feces showed greater abundance of Lactobacillus, Bifidobacterium and Romboutsia than feces from mice with low stress resilience, as well as lower abundance of Staphylococcus, Psychrobacter and Corynebacterium. Similarly, highly stress-resilient mice showed greater neurogenesis in hippocampus than animals with low stress resilience. Transplanting fecal microbiota from mice with high stress resilience into previously CUMS-exposed recipients rescued neurogenesis in hippocampus, facilitating recovery from stress-induced depression and cognitive decline. Blockade of neurogenesis with temozolomide abolished recovery of recipients from CUMS-induced depression and cognitive decline in mice transplanted with fecal microbiota from mice with high stress resilience. In conclusion, our results suggested that remodeling of the gut microbiome after stress may reverse stress-induced impairment of hippocampal neurogenesis and thereby promote recovery from stress-induced depression.

Potential of dietary polyphenols for protection from age-related decline and neurodegeneration: a role for gut microbiota?

Many epidemiological studies have shown the beneficial effects of a largely plant-based diet, and the strong association between the consumption of a Mediterranean-type diet with healthy aging including a lower risk of cognitive decline. The Mediterranean diet is characterized by a high intake of olive oil, fruits and vegetables and is rich in dietary fiber and polyphenols - both of which have been postulated to act as important mediators of these benefits. Polyphenols are large molecules produced by plants to protect them from environmental threats and injury. When ingested by humans, as little as 5% of these molecules are absorbed in the small intestine with the majority metabolized by the gut microbiota into absorbable simple phenolic compounds. Flavan-3-ols, a type of flavonoid, contained in grapes, berries, pome fruits, tea, and cocoa have been associated with many beneficial effects on several risk factors for cardiovascular disease, cognitive function and brain regions involved in memory formation. Both preclinical and clinical studies suggest that these brain and heart benefits can be attributed to endothelial vascular effects and anti-inflammatory properties among others. More recently the gut microbiota has emerged as a potential modulator of the aging brain and intriguingly polyphenols have been shown to alter microbiota composition and be metabolized by different microbial species. However, there is a need for well controlled studies in large populations to identify predictors of response, particularly given the vast inter-individual variation of human gut microbiota.

Decoding the role of the gut microbiome in gut-brain axis, stress-resilience, or stress-susceptibility: A review

Increased exposure to stress is associated with stress-related disorders, including depression, anxiety, and neurodegenerative conditions. However, susceptibility to stress is not seen in every individual exposed to stress, and many of them exhibit resilience. Thus, developing resilience to stress could be a big breakthrough in stress-related disorders, with the potential to replace or act as an alternative to the available therapies. In this article, we have focused on the recent advancements in gut microbiome research and the potential role of the gut-brain axis (GBA) in developing resilience or susceptibility to stress. There might be a complex interaction between the autonomic nervous system (ANS), immune system, endocrine system, microbial metabolites, and bioactive lipids like short-chain fatty acids (SCFAs), neurotransmitters, and their metabolites that regulates the communication between the gut microbiota and the brain. High fiber intake, prebiotics, probiotics, plant supplements, and fecal microbiome transplant (FMT) could be beneficial against gut dysbiosis-associated brain disorders. These could promote the growth of SCFA-producing bacteria, thereby enhancing the gut barrier and reducing the gut inflammatory response, increase the expression of the claudin-2 protein associated with the gut barrier, and maintain the blood-brain barrier integrity by promoting the expression of tight junction proteins such as claudin-5. Their neuroprotective effects might also be related to enhancing the expression of brain-derived neurotrophic factor (BDNF) and glucagon-like peptide (GLP-1). Further investigations are needed in the field of the gut microbiome for the elucidation of the mechanisms by which gut dysbiosis contributes to the pathophysiology of neuropsychiatric disorders.

Chronic Stress as a Risk Factor for Type 2 Diabetes: Endocrine, Metabolic, and Immune Implications

BACKGROUND

Chronic stress is a condition of pressure on the brain and whole body, which in the long term may lead to a frank disease status, even including type 2 diabetes (T2D). Stress activates the hypothalamus-pituitary-adrenal axis with release of glucocorticoids (GCs) and catecholamines, as well as activation of the inflammatory pathway of the immune system, which alters glucose and lipid metabolism, ultimately leading to beta-cell destruction, insulin resistance and T2D onset. Alteration of the glucose and lipid metabolism accounts for insulin resistance and T2D outcome. Furthermore, stress-related subversion of the intestinal microbiota leads to an imbalance of the gut-brain-immune axis, as evidenced by the stress-related depression often associated with T2D. A condition of generalized inflammation and subversion of the intestinal microbiota represents another facet of stress-induced disease. In fact, chronic stress acts on the gut-brain axis with multiorgan consequences, as evidenced by the association between depression and T2D. Oxidative stress with the production of reactive oxygen species and cytokine-mediated inflammation represents the main hallmarks of chronic stress. ROS production and pro-inflammatory cytokines represent the main hallmarks of stress-related disorders, and therefore, the use of natural antioxidant and anti-inflammatory substances (nutraceuticals) may offer an alternative therapeutic approach to combat stress-related T2D. Single or combined administration of nutraceuticals would be very beneficial in targeting the neuro-endocrine-immune axis, thus, regulating major pathways involved in T2D onset. However, more clinical trials are needed to establish the effectiveness of nutraceutical treatment, dosage, time of administration and the most favorable combinations of compounds. Therefore, in view of their antioxidant and anti-inflammatory properties, the use of natural products or nutraceuticals for the treatment of stress-related diseases, even including T2D, will be discussed. Several evidences suggest that chronic stress represents one of the main factors responsible for the outcome of T2D.

Mechanisms of microRNA-132 in central neurodegenerative diseases: A comprehensive review

MicroRNA-132 (miR-132) is a highly conserved molecule that plays a crucial regulatory role in central nervous system (CNS) disorders. The expression levels of miR-132 exhibit variability in various neurological disorders and have been closely linked to disease onset and progression. The expression level of miR-132 in the CNS is regulated by a diverse range of stimuli and signaling pathways, including neuronal migration and integration, dendritic outgrowth, and complexity, synaptogenesis, synaptic plasticity, as well as inflammation and apoptosis activation. The aberrant expression of miR-132 in various central neurodegenerative diseases has garnered widespread attention. Clinical studies have revealed altered miR-132 expression levels in both chronic and acute CNS diseases, positioning miR-132 as a potential biomarker or therapeutic target. An in-depth exploration of miR-132 holds the promise of enhancing our understanding of the mechanisms underlying CNS diseases, thereby offering novel insights and strategies for disease diagnosis and treatment. It is anticipated that this review will assist researchers in recognizing the potential value of miR-132 and in generating innovative ideas for clinical trials related to CNS degenerative diseases.

Gut-brain axis interacts with immunomodulation in inflammatory bowel disease

The brain and the gastrointestinal (GI) tract are important sensory organs in the body and the two-way interaction that exists between them regulates key physiological and homeostatic functions. A growing body of research suggests that this bidirectional communication influences the development and progression of functional GI disorders and plays an important role in the treatment of central nervous system (CNS) disorders. Inflammatory bowel disease (IBD) is a classic intestinal disorder with a high prevalence but still unclear pathogenesis that has been widely discussed in recent years. However, in the studies available to date, we find that many authors have chosen to discuss the influence of the brain on intestinal disorders from the top down, starting with physical and psychological disorders. Coming very naturally, based on these substantial research evidence, we focus on exploring the links between bidirectional communication in the gut-brain axis and IBD, and highlight the role of the gut microbiota, vagus nerve (VN), receptors and immune cells involved in regulating IBD through the gut-brain axis in this review.

Effects of Mycobacterium vaccae NCTC 11659 and Lipopolysaccharide Challenge on Polarization of Murine BV-2 Microglial Cells

Previous studies have shown that the in vivo administration of soil-derived bacteria with anti-inflammatory and immunoregulatory properties, such as Mycobacterium vaccae NCTC 11659, can prevent a stress-induced shift toward an inflammatory M1 microglial immunophenotype and microglial priming in the central nervous system (CNS). It remains unclear whether M. vaccae NCTC 11659 can act directly on microglia to mediate these effects. This study was designed to determine the effects of M. vaccae NCTC 11659 on the polarization of naïve BV-2 cells, a murine microglial cell line, and BV-2 cells subsequently challenged with lipopolysaccharide (LPS). Briefly, murine BV-2 cells were exposed to 100 µg/mL whole-cell, heat-killed M. vaccae NCTC 11659 or sterile borate-buffered saline (BBS) vehicle, followed, 24 h later, by exposure to 0.250 µg/mL LPS (Escherichia coli 0111: B4; n = 3) in cell culture media vehicle (CMV) or a CMV control condition. Twenty-four hours after the LPS or CMV challenge, cells were harvested to isolate total RNA. An analysis using the NanoString platform revealed that, by itself, M. vaccae NCTC 11659 had an "adjuvant-like" effect, while exposure to LPS increased the expression of mRNAs encoding proinflammatory cytokines, chemokine ligands, the C3 component of complement, and components of inflammasome signaling such as Nlrp3. Among LPS-challenged cells, M. vaccae NCTC 11659 had limited effects on differential gene expression using a threshold of 1.5-fold change. A subset of genes was assessed using real-time reverse transcription polymerase chain reaction (real-time RT-PCR), including Arg1, Ccl2, Il1b, Il6, Nlrp3, and Tnf. Based on the analysis using real-time RT-PCR, M. vaccae NCTC 11659 by itself again induced "adjuvant-like" effects, increasing the expression of Il1b, Il6, and Tnf while decreasing the expression of Arg1. LPS by itself increased the expression of Ccl2, Il1b, Il6, Nlrp3, and Tnf while decreasing the expression of Arg1. Among LPS-challenged cells, M. vaccae NCTC 11659 enhanced LPS-induced increases in the expression of Nlrp3 and Tnf, consistent with microglial priming. In contrast, among LPS-challenged cells, although M. vaccae NCTC 11659 did not fully prevent the effects of LPS relative to vehicle-treated control conditions, it increased Arg1 mRNA expression, suggesting that M. vaccae NCTC 11659 induces an atypical microglial phenotype. Thus, M. vaccae NCTC 11659 acutely (within 48 h) induced immune-activating and microglial-priming effects when applied directly to murine BV-2 microglial cells, in contrast to its long-term anti-inflammatory and immunoregulatory effects observed on the CNS when whole-cell, heat-killed preparations of M. vaccae NCTC 11659 were given peripherally in vivo.

Broadening Horizons: Exploring mtDAMPs as a Mechanism and Potential Intervention Target in Cardiovascular Diseases

Cardiovascular diseases (CVDs) have been recognized as the leading cause of premature mortality and morbidity worldwide despite significant advances in therapeutics. Inflammation is a key factor in CVD progression. Once stress stimulates cells, they release cellular compartments known as damage-associated molecular patterns (DAMPs). Mitochondria can release mitochondrial DAMPs (mtDAMPs) to initiate an immune response when stimulated with cellular stress. Investigating the molecular mechanisms underlying the DAMPs that regulate CVD progression is crucial for improving CVDs. Herein, we discuss the composition and mechanism of DAMPs, the significance of mtDAMPs in cellular inflammation, the presence of mtDAMPs in different types of cells, and the main signaling pathways associated with mtDAMPs. Based on this, we determined the role of DAMPs in CVDs and the effects of mtDAMP intervention on CVD progression. By offering a fresh perspective and comprehensive insights into the molecular mechanisms of DAMPs, this review seeks to provide important theoretical foundations for developing drugs targeting CVDs.

Bioavailability of bioactive compounds in Hibiscus sabdariffa beverage as a potential anti-inflammatory

The absorption and metabolism of bioactive compounds (BCs) in a Hibiscus sabdariffa drink (HbD) were evaluated by the in vivo bioavailability of organic acids (OA) and phenolic compounds (PC's). An acute single-blind clinical study in humans was conducted. Twelve volunteers consumed a HbD and a control drink (CD). Urine and plasma samples were taken after consuming both beverages. OA and PC's of the beverages (HbD and CD) and the biological samples (urine and plasma) were characterized by HPLC-DAD-MS. Thirthy-eight compounds in HbD and four CD were detected and quantified, equivalent to 937.37 mg and 1.22 mg per 60 mL, respectively. Hibiscus acid was the most abundant OA in both drinks. Additionally, hydroxycinnamic acids, flavonoids, anthocyanins, and anthocyanidins were also detected in HbD, although their amount represented 10% of the total BCs. 25 different metabolites were identified, 15 in urine and 23 in plasma. The microbiota extensively biotransformed PCs and their amount was lower than organic acids, particularly hibiscus acid and hydroxycitric acid. The colonic metabolites derived from PCs and organic acids would be behind the anti-inflammatory bioactivity described for Hibiscus sabdariffa L. (Malvaceae family). However, further studies are necessary to evaluate the metabolites responsible for their anti-inflammatory activity.

Th17 Cells, Glucocorticoid Resistance, and Depression

Depression is a severe mental disorder that disrupts mood and social behavior and is one of the most common neuropsychological symptoms of other somatic diseases. During the study of the disease, a number of theories were put forward (monoamine, inflammatory, vascular theories, etc.), but none of those theories fully explain the pathogenesis of the disease. Steroid resistance is a characteristic feature of depression and can affect not only brain cells but also immune cells. T-helper cells 17 type (Th17) are known for their resistance to the inhibitory effects of glucocorticoids. Unlike the inhibitory effect on other subpopulations of T-helper cells, glucocorticoids can enhance the differentiation of Th17 lymphocytes, their migration to the inflammation, and the production of IL-17A, IL-21, and IL-23 in GC-resistant disease. According to the latest data, in depression, especially the treatment-resistant type, the number of Th17 cells in the blood and the production of IL-17A is increased, which correlates with the severity of the disease. However, there is still a significant gap in knowledge regarding the exact mechanisms by which Th17 cells can influence neuroinflammation in depression. In this review, we discuss the mutual effect of glucocorticoid resistance and Th17 lymphocytes on the pathogenesis of depression.

PitNETs and the gut microbiota: potential connections, future directions

The role of the gut microbiome has been widely discussed in numerous works of literature. The biggest concern is the association of the gut microbiome with the central nervous system through the microbiome-brain-gut axis in the past ten years. As more and more research has been done on the relationship between the disease of the central nervous system and gut microbes. This fact is being revealed that gut microbes seem to play an important role from the onset and progression of the disease to clinical symptoms, and new treatments. As a special tumor of the central nervous system, pituitary neuroendocrine tumors (PitNETs)are closely related to metabolism, endocrinology, and immunity. These factors are the vectors through which intestinal microbes interact with the central nervous system. However, little is known about the effects of gut microbes on the PitNET. In this review, the relationship of gut microbiota in PitNETs is introduced, the potential effects of the gut-brain axis in this relationship are analyzed, and future research directions are presented.

The influence of gut microbiota on circulating inflammatory cytokines and host: A Mendelian randomization study with meta-analysis

AIMS

The gut microbiota has been found to be altered in different inflammatory disorders, but its involvement in the regulation of inflammatory cytokines remains unclear. Therefore, this study aimed to investigate the impacts of gut microbiota on circulating inflammatory cytokines and their potential roles in host diseases.

MAIN METHODS

Two-sample Mendelian randomization (MR) analyses were conducted using summary-level data from genome-wide association studies (GWAS) to identify significant causal associations between 196 gut microbiota and 41 inflammatory cytokines. Meta-analysis was applied to test the robustness of the results. Enrichment analyses of identified cytokines were further utilized to infer the effects of gut microbiota on the host.

KEY FINDINGS

The MR analyses and meta-analyses identified the following significant causal associations: phylum Euryarchaeota on interleukin-2 (IL-2) (βIVW = 0.085, P = 1.5 × 10-2) and interleukin-8 (IL-8) (βIVW = 0.065, P = 4.1 × 10-2), phylum Tenericutes and class Mollicutes on macrophage inflammatory protein 1a (MIP1a) (βIVW = -0.142, P = 7.0 × 10-3), class Bacilli on hepatocyte growth factor (HGF) (βIVW = -0.106, P = 2.5 × 10-2), order Enterobacteriales on monocyte chemoattractant protein-1 (MCP1) (βIVW = 0.182, P = 1.8 × 10-2), and genus Lachnospiraceae NC2004 group on TNF-related apoptosis-inducing ligand (TRAIL) (βIVW = -0.207, P = 6.0 × 10-4). Enrichment analyses suggested that phylum Euryarchaeota and order Enterobacteriales might be risk factors for certain autoimmune diseases and neoplasms, while the phylum Tenericutes may have a protective effect.

SIGNIFICANCE

This study represents the first evidence confirming the causal effect of specific gut microbial taxa on circulating inflammatory cytokines and sheds light on their potential roles in the development and progression of various host diseases.

The Bioactive Dietary Polyphenol Preparation Alleviates Depression and Anxiety-Like Behaviors by Modulating the Regional Heterogeneity of Microglia Morphology

SCOPE

The goal of this study is to investigate the effects of a bioactive dietary polyphenol preparation (BDPP), which is made up of grape-derived polyphenols, on microglial responses, as well as the underlying molecular mechanisms in depression and anxiety-like behaviors.

METHODS AND RESULTS

The study finds that treatment with BDPP significantly decreases depression-like and anxiety-like behaviors induced by chronic stress in mice, while leaving their locomotor activity unaffected. The study also finds that BDPP treatment reverses microglia activation in the amygdala and hippocampal formation, regions of the brain involved in emotional regulation, from an amoeboid shape to ramified shape. Additionally, BDPP treatment modulates the release of pro-inflammatory cytokines such as interleukin-6 via high mobility box 1 protein and the receptor for advanced glycation end products (HMGB1-RAGE) signaling pathway in activated microglia induced by chronic stress.

CONCLUSION

The findings suggest regional heterogeneity in microglial responses following chronic stress in subregions of the corticolimbic circuit. Specifically, activation of the immune-inflammatory HMGB1-RAGE pathway may provide a new avenue for preventing the manifestation of psychiatric impairments including stress-induced anxiety- and depression-like behavior, using bioactive and bioavailable polyphenols.

CCK1R2R-/- ameliorates myocardial damage caused by unpredictable stress via altering fatty acid metabolism

The heart is the main organ of the circulatory system and requires fatty acids to maintain its activity. Stress is a contributor to aggravating cardiovascular diseases and even death, and exacerbates the abnormal lipid metabolism. The cardiac metabolism may be disturbed by stress. Cholecystokinin (CCK), which is a classical peptide hormone, and its receptor (CCKR) are expressed in myocardial cells and affect cardiovascular function. Nevertheless, under stress, the exact role of CCKR on cardiac function and cardiac metabolism is unknown and the mechanism is worth exploring. After unpredictable stress, a common stress-inducing model that induces the development of mood disorders such as anxiety and reduces motivated behavior, we found that the abnormal contraction and diastole of the heart, myocardial injury, oxidative stress and inflammation of mice were aggravated. Cholecystokinin A receptor and cholecystokinin B receptor knockout (CCK1R2R-/-) significantly reversed these changes. Mechanistically, fatty acid metabolism was found to be altered in CCK1R2R-/- mice. Differential metabolites, especially L-tryptophan, L-aspartic acid, cholesterol, taurocholic acid, ADP, oxoglutaric acid, arachidonic acid and 17-Hydroxyprogesterone, influenced cardiac function after CCK1R2R knockout and unpredictable stress. We conclude that CCK1R2R-/- ameliorated myocardial damage caused by unpredictable stress via altering fatty acid metabolism.

Mitochondria of intestinal epithelial cells in depression: Are they at a crossroads of gut-brain communication?

The role of gut dysbiosis in depression is well established. However, recent studies have shown that gut microbiota is regulated by intestinal epithelial cell (IEC) mitochondria, which has yet to receive much attention. This review summarizes the recent developments about the critical role of IEC mitochondria in actively maintaining gut microbiota, intestinal metabolism, and immune homeostasis. We propose that IEC mitochondrial dysfunction alters gut microbiota composition, participates in cell fate, mediates oxidative stress, activates the peripheral immune system, causes peripheral inflammation, and transmits peripheral signals through the vagus and enteric nervous systems. These pathological alterations lead to brain inflammation, disruption of the blood-brain barrier, activation of the hypothalamic-pituitary-adrenal axis, activation of microglia and astrocytes, induction of neuronal loss, and ultimately depression. Furthermore, we highlight the prospect of treating depression through the mitochondria of IECs. These new findings suggest that the mitochondria of IECs may be a newly found important factor in the pathogenesis of depression and represent a potential new strategy for treating depression.

Gut microbiota in brain tumors: An emerging crucial player

In recent decades, various roles of the gut microbiota in physiological and pathological conditions have been uncovered. Among the many interacting pathways between the host and gut flora, the gut-brain axis has drawn increasing attention and is generally considered a promising way to understand and treat brain tumors, one of the most lethal neoplasms. In this narrative review, we aimed to unveil and dissect the sophisticated mechanisms by which the gut-brain axis exerts its influence on brain tumors. Furthermore, we summarized the latest research regarding the gastrointestinal microbial landscape and the effect of gut-brain axis malfunction on different brain tumors. Finally, we outlined the ongoing developing approaches of microbial manipulation and their corresponding research related to neuro-malignancies. Collectively, we recapitulated the advances in gut microbial alterations along with their potential interactive mechanisms in brain tumors and encouraged increased efforts in this area.

T cells: an emerging cast of roles in bipolar disorder

Bipolar disorder (BD) is a distinctly heterogeneous and multifactorial disorder with a high individual and social burden. Immune pathway dysregulation is an important pathophysiological feature of BD. Recent studies have suggested a potential role for T lymphocytes in the pathogenesis of BD. Therefore, greater insight into T lymphocytes' functioning in patients with BD is essential. In this narrative review, we describe the presence of an imbalance in the ratio and altered function of T lymphocyte subsets in BD patients, mainly in T helper (Th) 1, Th2, Th17 cells and regulatory T cells, and alterations in hormones, intracellular signaling, and microbiomes may be potential causes. Abnormal T cell presence explains the elevated rates of comorbid inflammatory illnesses in the BD population. We also update the findings on T cell-targeting drugs as potentially immunomodulatory therapeutic agents for BD disease in addition to classical mood stabilizers (lithium, valproic acid). In conclusion, an imbalance in T lymphocyte subpopulation ratios and altered function may be involved in the development of BD, and maintaining T cell immune homeostasis may provide an overall therapeutic benefit.

T helper 17 (Th17) cell responses to the gut microbiota in human diseases

The gut microbiota colonizing the gastrointestinal tract, is an indispensable "invisible organ" that affects multiple aspects of human health. The gut microbial community has been assumed to be an important stimulus to the immune homeostasis and development, and increasing data support the role of the gut microbiota-immunity axis in autoimmune diseases. Host's immune system requires recognition tools to communicate with the gut microbial evolutionary partners. Among these microbial perceptions, T cells enable the widest spectrum of gut microbial recognition resolution. Specific gut microbiota direct the induction and differentiation of Th17 cells in intestine. However, the detailed links between the gut microbiota and Th17 cells have not been well established. In this review, we describe the generation and characterization of Th17 cells. Notably, we discuss the induction and differentiation of Th17 cells by the gut microbiota and their metabolites, as well as recent advances in our understanding of interactions between Th17 cells and the gut microbiota in human diseases. In addition, we provide the emerging evidences in support of interventions targeting the gut microbes/Th17 cells in human diseases.

The Role of Adipokines in Health and Disease

Adipokines are cell-signaling proteins secreted by adipose tissue that has been related to a low-grade state of inflammation and different pathologies. The present review aims to analyze the role of adipokines in health and disease in order to understand the important functions and effects of these cytokines. For this aim, the present review delves into the type of adipocytes and the cytokines produced, as well as their functions; the relations of adipokines in inflammation and different diseases such as cardiovascular, atherosclerosis, mental diseases, metabolic disorders, cancer, and eating behaviors; and finally, the role of microbiota, nutrition, and physical activity in adipokines is discussed. This information would allow for a better understanding of these important cytokines and their effects on body organisms.

Small molecule metabolites: discovery of biomarkers and therapeutic targets

Metabolic abnormalities lead to the dysfunction of metabolic pathways and metabolite accumulation or deficiency which is well-recognized hallmarks of diseases. Metabolite signatures that have close proximity to subject's phenotypic informative dimension, are useful for predicting diagnosis and prognosis of diseases as well as monitoring treatments. The lack of early biomarkers could lead to poor diagnosis and serious outcomes. Therefore, noninvasive diagnosis and monitoring methods with high specificity and selectivity are desperately needed. Small molecule metabolites-based metabolomics has become a specialized tool for metabolic biomarker and pathway analysis, for revealing possible mechanisms of human various diseases and deciphering therapeutic potentials. It could help identify functional biomarkers related to phenotypic variation and delineate biochemical pathways changes as early indicators of pathological dysfunction and damage prior to disease development. Recently, scientists have established a large number of metabolic profiles to reveal the underlying mechanisms and metabolic networks for therapeutic target exploration in biomedicine. This review summarized the metabolic analysis on the potential value of small-molecule candidate metabolites as biomarkers with clinical events, which may lead to better diagnosis, prognosis, drug screening and treatment. We also discuss challenges that need to be addressed to fuel the next wave of breakthroughs.

The potential for treg-enhancing therapies in nervous system pathologies

While inflammation may not be the cause of disease, it is well known that it contributes to disease pathogenesis across a multitude of peripheral and central nervous system disorders. Chronic and overactive inflammation due to an effector T-cell-mediated aberrant immune response ultimately leads to tissue damage and neuronal cell death. To counteract peripheral and neuroinflammatory responses, research is being focused on regulatory T cell enhancement as a therapeutic target. Regulatory T cells are an immunosuppressive subpopulation of CD4+ T helper cells essential for maintaining immune homeostasis. The cells play pivotal roles in suppressing immune responses to maintain immune tolerance. In so doing, they control T cell proliferation and pro-inflammatory cytokine production curtailing autoimmunity and inflammation. For nervous system pathologies, Treg are known to affect the onset and tempo of neural injuries. To this end, we review recent findings supporting Treg's role in disease, as well as serving as a therapeutic agent in multiple sclerosis, myasthenia gravis, Guillain-Barre syndrome, Parkinson's and Alzheimer's diseases, and amyotrophic lateral sclerosis. An ever-broader role for Treg in the control of neurologic disease has been shown for traumatic brain injury, stroke, neurotrophic pain, epilepsy, and psychiatric disorders. To such ends, this review serves to examine the role played by Tregs in nervous system diseases with a focus on harnessing their functional therapeutic role(s).

Interaction between gut microbiota and sex hormones and their relation to sexual dimorphism in metabolic diseases

Metabolic diseases, such as obesity, metabolic syndrome (MetS) and type 2 diabetes (T2D), are now a widespread pandemic in the developed world. These pathologies show sex differences in their development and prevalence, and sex steroids, mainly estrogen and testosterone, are thought to play a prominent role in this sexual dimorphism. The influence of sex hormones on these pathologies is not only reflected in differences between men and women, but also between women themselves, depending on the hormonal changes associated with the menopause. The observed sex differences in gut microbiota composition have led to multiple studies highlighting the interaction between steroid hormones and the gut microbiota and its influence on metabolic diseases, ultimately pointing to a new therapy for these diseases based on the manipulation of the gut microbiota. This review aims to shed light on the role of sexual hormones in sex differences in the development and prevalence of metabolic diseases, focusing on obesity, MetS and T2D. We focus also the interaction between sex hormones and the gut microbiota, and in particular the role of microbiota in aspects such as gut barrier integrity, inflammatory status, and the gut-brain axis, given the relevance of these factors in the development of metabolic diseases.

The Development of Systemic Inflammatory Diseases in Hidradenitis Suppurativa

It is understood that the skin is a peripheral lymphoid tissue that defends against external environmental stimuli. Continuous activation from these factors, on the other hand, promotes persistent inflammation at the local location and, occasionally, tissue damage. Hidradenitis suppurativa (HS) is a typical inflammatory skin disease and becomes a source of numerous inflammatory cytokines due to the chronic intractable repeated inflamed tissues. Because inflammatory cells and cytokines circulate throughout the body from the inflamed organ, it has been hypothesized that HS-mediated skin inflammation impacts the systemic functioning of numerous organs. Recent updates to clinical and experimental investigations revealed that HS has a significant connection with systemic inflammatory disorders. We provide the details and comprehensive molecular mechanisms associated with systemic inflammatory illnesses due to HS.

Acupuncture treatment for post-stroke depression: Intestinal microbiota and its role

Stroke-induced depression is a common complication and an important risk factor for disability. Besides psychiatric symptoms, depressed patients may also exhibit a variety of gastrointestinal symptoms, and even take gastrointestinal symptoms as the primary reason for medical treatment. It is well documented that stress may disrupt the balance of the gut microbiome in patients suffering from post-stroke depression (PSD), and that disruption of the gut microbiome is closely related to the severity of the condition in depressed patients. Therefore, maintaining the balance of intestinal microbiota can be the focus of research on the mechanism of acupuncture in the treatment of PSD. Furthermore, stroke can be effectively treated with acupuncture at all stages and it may act as a special microecological regulator by regulating intestinal microbiota as well. In this article, we reviewed the studies on changing intestinal microbiota after acupuncture treatment and examined the existing problems and development prospects of acupuncture, microbiome, and poststroke depression, in order to provide new ideas for future acupuncture research.

Distinct metabolic biomarkers to distinguish IgG4-related disease from Sjogren's syndrome and pancreatic cancer and predict disease prognosis

BACKGROUND

The pathogenesis of immunoglobulin G4-related disease (IgG4-RD) remains unclear. IgG4-RD often mimics other diseases, including pancreatic cancer (PC) and Sjogren's syndrome (SS), which may easily lead to misdiagnosis. This study was performed to explore the metabolite changes and potential biomarkers of IgG4-RD and other misdiagnosed diseases.

METHODS

Untargeted liquid chromatography-tandem mass spectrometry metabolomics profiling of plasma samples from a cohort comprising healthy controls (HCs) and patients with IgG4-RD (n = 87), PC (n = 33), and SS (n = 31) was performed. A random forest machine learning model was used to verify the relevance of the identified metabolites in the diagnosis of different diseases and the prediction of disease prognosis.

RESULTS

The ATP-binding cassette transporter pathway was found to be most closely related to IgG4-RD, which was significantly up-regulated in the IgG4-RD group than in all the matched groups. Five metabolites were proved to be valuable biomarkers for IgG4-RD. Caftaric acid, maltotetraose, D-glutamic acid, 1-stearoyl-2-arachidonoyl-sn-glycero-3-phosphoserine, and hydroxyproline were useful in distinguishing between IgG4-RD, PC, SS, and HC [area under the curve (AUC) = 1]. A combination of phenylalanine betaine, 1-(1z-hexadecenyl)-sn-glycero-3-phosphocholine, Pi 40:8, uracil, and N1-methyl-2-pyridone-5-carboxamide showed a moderate value in predicting relapse in patients with IgG4-RD (AUC = 0.8).

CONCLUSIONS

Our findings revealed the metabolite changes of IgG4-RD and provide new insights for deepening our understanding of IgG4-RD despite the lack of validation in external cohorts. Metabolomic biomarkers have significance in the clinical diagnosis and disease prognosis of IgG4-RD.

Once induced, it lasts for a long time: the structural and molecular signatures associated with depressive-like behavior after neonatal immune activation

Adverse factors such as stress or inflammation in the neonatal period can affect the development of certain brain structures and have negative delayed effects throughout the lifespan of an individual, by reducing cognitive abilities and increasing the risk of psychopathologies. One possible reason for these delayed effects is the neuroinflammation caused by neonatal immune activation (NIA). Neuroinflammation can lead to disturbances of neurotransmission and to reprogramming of astroglial and microglial brain cells; when combined, the two problems can cause changes in the cytoarchitecture of individual regions of the brain. In addition, neuroinflammation may affect the hypothalamic-pituitary-adrenal (HPA) axis and processes of oxidative stress, thereby resulting in higher stress reactivity. In our review, we tried to answer the questions of whether depressive-like behavior develops after NIA in rodents and what the molecular mechanisms associated with these disorders are. Most studies indicate that NIA does not induce depressive-like behavior in a steady state. Nonetheless, adult males (but not females or adolescents of both sexes) with experience of NIA exhibit marked depressive-like behavior when exposed to aversive conditions. Analyses of molecular changes have shown that NIA leads to an increase in the amount of activated microglia and astroglia in the frontal cortex and hippocampus, an increase in oxidative-stress parameters, a change in stress reactivity of the HPA axis, and an imbalance of cytokines in various regions of the brain, but not in blood plasma, thus confirming the local nature of the inflammation. Therefore, NIA causes depressive-like behavior in adult males under aversive testing conditions, which are accompanied by local inflammation and have sex- and age-specific effects.

T-cell activation state differentially contributes to neuropsychiatric complications in women with HIV

Neuropsychiatric complications are common among women with HIV (WWH). The pathophysiological mechanisms underlying these complications are not fully known but likely driven in part by immune modulation. We examined associations between T-cell activation states which are required to mount an effective immune response (activation, co-stimulation/normal function, exhaustion, senescence) and neuropsychiatric complications in WWH. 369 WWH (78% HIV RNA undetectable/<20cp/mL) enrolled in the Women's Interagency HIV Study completed neuropsychological testing and measures of depression (Center for Epidemiological Studies Depression Scale-CES-D), self-reported stress levels (Perceived Stress Scale-10), and post-traumatic stress (PTSD Checklist-Civilian Scale). Multiparametric flow cytometry evaluated T-cell activation state. Partial least squares regressions were used to examine T-cell phenotypes and neuropsychiatric outcome associations after confounder adjustment. In the total sample and among virally suppressed (VS)-WWH, CD4+ T-cell exhaustion was associated with poorer learning and attention/working memory (P's < 0.05). In the total sample, CD4+ T-cell activation was associated with better attention/working memory and CD8+ T-cell co-stimulation and senescence was associated with poorer executive function (P's < 0.05). For mental health outcomes, in the total sample, CD4+ T-cell activation was associated with more perceived stress and CD4+ T-cell exhaustion was associated with less depressive symptoms (P's < 0.05). Among VS-WWH, CD4+ senescence was associated with less perceive stress and CD8+ T-cell co-stimulation and senescence was associated with higher depression (P's < 0.05). Together, results suggest the contribution of peripheral CD4+ and CD8+ T-cell activation status to neuropsychiatric complications in WWH.

Psychological stress in inflammatory bowel disease: Psychoneuroimmunological insights into bidirectional gut–brain communications

Inflammatory bowel disease (IBD), mainly including ulcerative colitis (UC) and Crohn’s disease (CD), is an autoimmune gastrointestinal disease characterized by chronic inflammation and frequent recurrence. Accumulating evidence has confirmed that chronic psychological stress is considered to trigger IBD deterioration and relapse. Moreover, studies have demonstrated that patients with IBD have a higher risk of developing symptoms of anxiety and depression than healthy individuals. However, the underlying mechanism of the link between psychological stress and IBD remains poorly understood. This review used a psychoneuroimmunology perspective to assess possible neuro-visceral integration, immune modulation, and crucial intestinal microbiome changes in IBD. Furthermore, the bidirectionality of the brain–gut axis was emphasized in the context, indicating that IBD pathophysiology increases the inflammatory response in the central nervous system and further contributes to anxiety- and depression-like behavioral comorbidities. This information will help accurately characterize the link between psychological stress and IBD disease activity. Additionally, the clinical application of functional brain imaging, microbiota-targeted treatment, psychotherapy and antidepressants should be considered during the treatment and diagnosis of IBD with behavioral comorbidities. This review elucidates the significance of more high-quality research combined with large clinical sample sizes and multiple diagnostic methods and psychotherapy, which may help to achieve personalized therapeutic strategies for IBD patients based on stress relief.

Role of inflammatory factors in the etiology and treatment of recurrent implantation failure

Recurrent implantation failure (RIF) is characterized by the absence of implantation after high-grade embryos are transferred to the endometrium by at least three in vitro fertilization cycles. It is one of the most important factors contributing to reproductive failure. After numerous barriers have been overcome to obtain good-quality embryos, RIF causes extreme distress and frustration in women and couples. In recent years, significant progress has been made in understanding how inflammatory factors, which include pro-inflammatory factors, anti-inflammatory factors, chemokines, and other molecules, contribute to RIF. Immunological abnormalities, hypercoagulability, and reproductive diseases are considered potential causes of RIF. In alloimmune disorders, inflammatory factors can affect the success rate of embryo implantation by altering T helper (Th)1/Th2 and Th17/regulatory T cell ratios and causing imbalances of uterine natural killer cells and macrophages. Autoimmune disorders can also lead to RIF. Inflammatory factors also play key roles in RIF-related disorders such as hypercoagulability, chronic endometritis, adenomyosis, hydrosalpinx, and endometriosis. This review focuses on the roles of inflammatory factors in RIF, including immune factors, blood hypercoagulable states, and reproductive diseases such as chronic endometritis, adenomyosis, hydrosalpinx, and endometriosis. It also summarizes the different treatments according to the causes of RIF and discusses the efficacy of sirolimus, peripheral blood mononuclear cells, low-dose aspirin combined with low-molecular-weight heparin, blocking interleukin-22, and gonadotropin-releasing hormone agonists in the treatment of RIF.

Abnormal microglial polarization induced by Arid1a deletion leads to neuronal differentiation deficits

OBJECTIVE

Microglia, the prototypical innate immune cells of the central nervous system (CNS), are highly plastic and assume their phenotypes dependent on intrinsically genetic, epigenetic regulation or extrinsically microenvironmental cues. Microglia has been recognized as key regulators of neural stem/progenitor cells (NSPCs) and brain functions. Chromatin accessibility is implicated in immune cell development and functional regulation. However, it is still unknown whether and how chromatin remodelling regulates the phenotypic plasticity of microglia and exerts what kind of effects on NSPCs.

METHODS

We investigated the role of chromatin accessibility in microglia by deleting chromatin remodelling gene Arid1a using microglia-specific Cx3cr1-cre and Cx3cr1-CreERT2 mice. RNA-seq and ATAC-seq were performed to dissect the molecular mechanisms. In addition, we examined postnatal M1/M2 microglia polarization and analysed neuronal differentiation of NSPCs. Finally, we tested the effects of microglial Arid1a deletion on mouse behaviours.

RESULTS

Increased chromatin accessibility upon Arid1a ablation resulted in enhanced M1 microglial polarization and weakened M2 polarization, which led to abnormal neurogenesis and anxiety-like behaviours. Switching the polarization state under IL4 stimulation could rescue abnormal neurogenesis, supporting an essential role for chromatin remodeler ARID1A in balancing microglial polarization and brain functions.

CONCLUSIONS

Our study identifies ARID1A as a central regulator of microglia polarization, establishing a mechanistic link between chromatin remodelling, neurogenesis and mouse behaviours, and highlights the potential development of innovative therapeutics exploiting the innate regenerative capacity of the nervous system.

TREGking From Gut to Brain: The Control of Regulatory T Cells Along the Gut-Brain Axis

The human gastrointestinal tract has an enormous and diverse microbial community, termed microbiota, that is necessary for the development of the immune system and tissue homeostasis. In contrast, microbial dysbiosis is associated with various inflammatory and autoimmune diseases as well as neurological disorders in humans by affecting not only the immune system in the gastrointestinal tract but also other distal organs. FOXP3⁺ regulatory T cells (Tregs) are a subset of CD4⁺ helper T cell lineages that function as a gatekeeper for immune activation and are essential for peripheral autoimmunity prevention. Tregs are crucial to the maintenance of immunological homeostasis and tolerance at barrier regions. Tregs reside in both lymphoid and non-lymphoid tissues, and tissue-resident Tregs have unique tissue-specific phenotype and distinct function. The gut microbiota has an impact on Tregs development, accumulation, and function in periphery. Tregs, in turn, modulate antigen-specific responses aimed towards gut microbes, which supports the host–microbiota symbiotic interaction in the gut. Recent studies have indicated that Tregs interact with a variety of resident cells in central nervous system (CNS) to limit the progression of neurological illnesses such as ischemic stroke, Alzheimer’s disease, and Parkinson’s disease. The gastrointestinal tract and CNS are functionally connected, and current findings provide insights that Tregs function along the gut-brain axis by interacting with immune, epithelial, and neuronal cells. The purpose of this study is to explain our current knowledge of the biological role of tissue-resident Tregs, as well as the interaction along the gut-brain axis.