Gut environment-induced intraepithelial autoreactive CD4(+) T cells suppress central nervous system autoimmunity via LAG-3

Contribution of gut-derived T cells to extraintestinal autoimmune diseases

The mammalian intestine harbors abundant T cells with high motility, where these cells can affect both intestinal and extraintestinal disorders. Growing evidence shows that gut-derived T cells migrate to extraintestinal organs, contributing to the pathogenesis of certain autoimmune diseases, including type 1 diabetes (T1D) and multiple sclerosis (MS). However, three key questions require further elucidation. First, how do intestinal T cells egress from the intestine? Second, how do gut-derived T cells enter organs outside the gut? Third, what is the pathogenicity of gut-derived T cells and their correlation with the gut microenvironment? In this Opinion, we propose answers to these questions. Understanding the migration and functional regulation of gut-derived T cells might inform precise targeting for achieving safe and effective approaches to treat certain extraintestinal autoimmune diseases.

Indirect suppression of CD4 T cell activation through LAG-3-mediated trans-endocytosis of MHC class II

Blockade of immune checkpoint receptors has shown outstanding efficacy for tumor immunotherapy. Promising treatment with anti-lymphocyte-activation gene-3 (LAG-3) has already been recognized as the next efficacious treatment, but there is still limited understanding of the mechanism of LAG-3-mediated immune suppression. Here, utilizing high-resolution molecular imaging, we find a mechanism of CD4 T cell suppression via LAG-3, in which LAG-3-bound major histocompatibility complex (MHC) class II molecules on antigen-presenting cells (APCs) gather at the central region of an immunological synapse and are trans-endocytosed by T cell receptor-driven internalization motility toward CD4 and CD8 T cells expressing LAG-3. Downregulation of MHC class II molecules on APCs thus results in the attenuation of their antigen-presentation function and impairment of CD4 T cell activation. From these data, anti-LAG-3 treatment is suggested to have potency to directly block the inhibitory signaling via LAG-3 and simultaneously reduce MHC class II expression on APCs by LAG-3-mediated trans-endocytosis for recovery from T cell exhaustion.

Human umbilical cord mesenchymal stem cell-derived exosomes alleviate the severity of experimental autoimmune encephalomyelitis and enhance lag-3 expression on foxp3 + CD4 + T cells

BACKGROUND

Multiple sclerosis (MS) is a complex autoimmune disease that affects the central nervous system, causing inflammation, demyelination, and neurodegeneration. Understanding the dysregulation of Tregs, dynamic cells involved in autoimmunity, is crucial in comprehending diseases like MS. However, the role of lymphocyte-activation gene 3 (Lag-3) in MS remains unclear.

METHODS

In this study, we explore the potential of exosomes derived from human umbilical cord mesenchymal stem cells (hUMSCs-Exs) as an immune modulator in experimental autoimmune encephalomyelitis (EAE), a model for MS.

RESULTS

Using flow cytometry, our research findings indicate that groups receiving treatment with hUMSC-Exs revealed a significant increase in Lag-3 expression on Foxp3 + CD4 + T cells. Furthermore, cell proliferation conducted on spleen tissue samples from EAE mice using the CFSE method exposed to hUMSC-Exs yielded relevant results.

CONCLUSIONS

These results suggest that hUMSCs-Exs could be a promising anti-inflammatory agent to regulate T-cell responses in EAE and other autoimmune diseases. However, further research is necessary to fully understand the underlying mechanisms and Lag-3's precise role in these conditions.

A dynamic atlas of immunocyte migration from the gut

Dysbiosis in the gut microbiota affects several systemic diseases, possibly by driving the migration of perturbed intestinal immunocytes to extraintestinal tissues. Combining Kaede photoconvertible mice and single-cell genomics, we generated a detailed map of migratory trajectories from the colon, at baseline, and in several models of intestinal and extraintestinal inflammation. All lineages emigrated from the colon in an S1P-dependent manner. B lymphocytes represented the largest contingent, with the unexpected circulation of nonexperienced follicular B cells, which carried a gut-imprinted transcriptomic signature. T cell emigration included distinct groups of RORγ+ and IEL-like CD160+ subsets. Gut inflammation curtailed emigration, except for dendritic cells disseminating to lymph nodes. Colon-emigrating cells distributed differentially to distinct sites of extraintestinal models of inflammation (psoriasis-like skin, arthritic synovium, and tumors). Thus, specific cellular trails originating in the gut and influenced by microbiota may shape peripheral immunity in varied ways.

Fecal Microbiota Transplantation in Amyotrophic Lateral Sclerosis: Clinical Protocol and Evaluation of Microbiota Immunity Axis

The fecal microbial transplantation (FMT) is a therapeutic transplant of fecal microbiota from healthy donors to patients. This practice is aimed at restoring eubiosis and rebalancing the enteric and systemic immune responses, and then eliminating pathogenic triggers of multiple disease, including neurodegenerative diseases. Alterations of gut microbiota (GM) affect the central nervous system (CNS) health, impacting neuro-immune interactions, synaptic plasticity, myelination, and skeletal muscle function. T-regulatory lymphocytes (Treg) are among the most important players in the pathogenesis of amyotrophic lateral sclerosis (ALS), altering the disease course. Along with circulating neuropeptides, other immune cells, and the gut-brain axis, the GM influences immunological tolerance and controls Treg's number and suppressive functions. A double-blind, controlled, multicenter study on FMT in ALS patients has been designed to evaluate if FMT can modulate neuroinflammation, by restoring Treg number, thus modifying disease activity and progression.

The Role of the Intestinal Microbiome in Multiple Sclerosis-Lessons to Be Learned from Hippocrates

Based on recent advances in research of chronic inflammatory conditions, there is a growing body of evidence that suggests a close correlation between the microbiota of the gastrointestinal tract and the physiologic activity of the immune system. This raises the idea that disturbances of the GI ecosystem contribute to the unfolding of chronic diseases including neurodegenerative pathologies. Here, we overview our current understanding on the putative interaction between the gut microbiota and the immune system from the aspect of multiple sclerosis, one of the autoimmune conditions accompanied by severe chronic neuroinflammation that affects millions of people worldwide.

Gut immune microenvironment and autoimmunity

A variety of immune cells or tissues are present in the gut to form the gut immune microenvironment by interacting with gut microbiota, and to maintain the gut immune homeostasis. Accumulating evidence indicated that gut microbiota dysbiosis might break the homeostasis of the gut immune microenvironment, which was associated with many health problems including autoimmune diseases. Moreover, disturbance of the gut immune microenvironment can also induce extra-intestinal autoimmune disorders through the migration of intestinal pro-inflammatory effector cells from the intestine to peripheral inflamed sites. This review discussed the composition of the gut immune microenvironment and its association with autoimmunity. These findings are expected to provide new insights into the pathogenesis of various autoimmune disorders, as well as novel strategies for the prevention and treatment against related diseases.

From bench to bedside: targeting lymphocyte activation gene 3 as a therapeutic strategy for autoimmune diseases

BACKGROUND

Immune checkpoints negatively regulate immune response, thereby playing an important role in maintaining immune homeostasis. Substantial studies have confirmed that blockade or deficiency of immune checkpoint pathways contributes to the deterioration of autoimmune diseases. In this context, focusing on immune checkpoints might provide alternative strategies for the treatment of autoimmunity. Lymphocyte activation gene 3 (LAG3), as a member of immune checkpoint, is critical in regulating immune responses as manifested in multiple preclinical studies and clinical trials. Recent success of dual-blockade of LAG3 and programmed death-1 in melanoma also supports the notion that LAG3 is a crucial regulator in immune tolerance.

METHODS

We wrote this review article by searching the PubMed, Web of Science and Google Scholar databases.

CONCLUSION

In this review, we summarize the molecular structure and the action mechanisms of LAG3. Additionally, we highlight its roles in diverse autoimmune diseases and discuss how the manipulation of the LAG3 pathway can serve as a promising therapeutic strategy as well as its specific mechanism with the aim of filling the gaps from bench to bedside.

Gut immune cell trafficking: inter-organ communication and immune-mediated inflammation

Immune cell trafficking is a complex and tightly regulated process that is indispensable for the body's fight against pathogens. However, it is also increasingly acknowledged that dysregulation of cell trafficking contributes to the pathogenesis of immune-mediated inflammatory diseases (IMIDs) in gastroenterology and hepatology, such as inflammatory bowel disease and primary sclerosing cholangitis. Moreover, altered cell trafficking has also been implicated as a crucial step in the immunopathogenesis of other IMIDs, such as rheumatoid arthritis and multiple sclerosis. Over the past few years, a central role of the gut in mediating these disorders has progressively emerged, and the partly microbiota-driven imprinting of particular cell trafficking phenotypes in the intestine seems to be crucially involved. Therefore, this Review highlights achievements in understanding immune cell trafficking to, within and from the intestine and delineates its consequences for immune-mediated pathology along the gut-liver, gut-joint and gut-brain axes. We also discuss implications for current and future therapeutic approaches that specifically interfere with homing, retention, egress and recirculation of immune cells.

Association between LAG3/CD4 Genes Variants and Risk for Multiple Sclerosis

Several recent works have raised the possibility of the contribution of the lymphocyte activation gene 3 (LAG3) protein in the inflammatory processes of multiple sclerosis (MS). Results of studies on the possible association between LAG3 gene variants and the risk of MS have been inconclusive. In this study, we tried to show the possible association between the most common single nucleotide variants (SNVs) in the CD4 and LAG3 genes (these two genes are closely related) and the risk of MS in the Caucasian Spanish population. We studied the genotypes and allelic variants CD4 rs1922452, CD4 rs951818, and LAG3 rs870849 in 300 patients diagnosed with MS and 400 healthy patients using specific TaqMan-based qPCR assays. We analyzed the possible influence of the genotype frequency on age at the onset of MS, the severity of MS, clinical evolutive subtypes of MS, and the HLADRB1*1501 genotype. The frequencies of the CD4 rs1922452, CD4 rs951818, and LAG3 rs870849 genotypes and allelic variants were not associated with the risk of MS and were unrelated to gender, age at onset and severity of MS, the clinical subtype of MS, and HLADRB1*1501 genotype. The results of the current study showed a lack of association between the CD4 rs1922452, CD4 rs951818, and LAG3 rs870849 SNVs and the risk of developing MS in the Caucasian Spanish population.

Metabolic regulation and function of T helper cells in neuroinflammation

Neuroinflammatory conditions such as multiple sclerosis (MS) are initiated by pathogenic immune cells invading the central nervous system (CNS). Autoreactive CD4⁺ T helper cells are critical players that orchestrate the immune response both in MS and in other neuroinflammatory autoimmune diseases including animal models that have been developed for MS. T helper cells are classically categorized into different subsets, but heterogeneity exists within these subsets. Untangling the more complex regulation of these subsets will clarify their functional roles in neuroinflammation. Here, we will discuss how differentiation, immune checkpoint pathways, transcriptional regulation and metabolic factors determine the function of CD4⁺ T cell subsets in CNS autoimmunity. T cells rely on metabolic reprogramming for their activation and proliferation to meet bioenergetic demands. This includes changes in glycolysis, glutamine metabolism and polyamine metabolism. Importantly, these pathways were recently also implicated in the fine tuning of T cell fate decisions during neuroinflammation. A particular focus of this review will be on the Th17/Treg balance and intra-subset functional states that can either promote or dampen autoimmune responses in the CNS and thus affect disease outcome. An increased understanding of factors that could tip CD4⁺ T cell subsets and populations towards an anti-inflammatory phenotype will be critical to better understand neuroinflammatory diseases and pave the way for novel treatment paradigms.

LAG3 ectodomain structure reveals functional interfaces for ligand and antibody recognition

The immune checkpoint receptor lymphocyte activation gene 3 protein (LAG3) inhibits T cell function upon binding to major histocompatibility complex class II (MHC class II) or fibrinogen-like protein 1 (FGL1). Despite the emergence of LAG3 as a target for next-generation immunotherapies, we have little information describing the molecular structure of the LAG3 protein or how it engages cellular ligands. Here we determined the structures of human and murine LAG3 ectodomains, revealing a dimeric assembly mediated by Ig domain 2. Epitope mapping indicates that a potent LAG3 antagonist antibody blocks interactions with MHC class II and FGL1 by binding to a flexible 'loop 2' region in LAG3 domain 1. We also defined the LAG3-FGL1 interface by mapping mutations onto structures of LAG3 and FGL1 and established that FGL1 cross-linking induces the formation of higher-order LAG3 oligomers. These insights can guide LAG3-based drug development and implicate ligand-mediated LAG3 clustering as a mechanism for disrupting T cell activation.

Fewer LAG-3+ T Cells in Relapsing-Remitting Multiple Sclerosis and Type 1 Diabetes

The coinhibitory receptor lymphocyte activation gene 3 (LAG-3) is an immune checkpoint molecule that negatively regulates T cell activation, proliferation, and homeostasis. Blockade or deletion of LAG-3 in autoimmune-prone backgrounds or induced-disease models has been shown to exacerbate disease. We observed significantly fewer LAG-3+ CD4 and CD8 T cells from subjects with relapsing-remitting multiple sclerosis (RRMS) and type 1 diabetes. Low LAG-3 protein expression was linked to alterations in mRNA expression and not cell surface cleavage. Functional studies inhibiting LAG-3 suggest that in subjects with RRMS, LAG-3 retains its ability to suppress T cell proliferation. However, LAG-3 expression was associated with the expression of markers of apoptosis, indicating a role for low LAG-3 in T cell resistance to cell death. In T cells from subjects with RRMS, we observed a global dysregulation of LAG-3 expression stemming from decreased transcription and persisting after T cell stimulation. These findings further support the potential clinical benefits of a LAG-3 agonist in the treatment of human autoimmunity.

A Comprehensive Review on the Role of the Gut Microbiome in Human Neurological Disorders

The human body is full of an extensive number of commensal microbes, consisting of bacteria, viruses, and fungi, collectively termed the human microbiome. The initial acquisition of microbiota occurs from both the external and maternal environments, and the vast majority of them colonize the gastrointestinal tract (GIT). These microbial communities play a central role in the maturation and development of the immune system, the central nervous system, and the GIT system and are also responsible for essential metabolic pathways. Various factors, including host genetic predisposition, environmental factors, lifestyle, diet, antibiotic or nonantibiotic drug use, etc., affect the composition of the gut microbiota. Recent publications have highlighted that an imbalance in the gut microflora, known as dysbiosis, is associated with the onset and progression of neurological disorders. Moreover, characterization of the microbiome-host cross talk pathways provides insight into novel therapeutic strategies. Novel preclinical and clinical research on interventions related to the gut microbiome for treating neurological conditions, including autism spectrum disorders, Parkinson's disease, schizophrenia, multiple sclerosis, Alzheimer's disease, epilepsy, and stroke, hold significant promise. This review aims to present a comprehensive overview of the potential involvement of the human gut microbiome in the pathogenesis of neurological disorders, with a particular emphasis on the potential of microbe-based therapies and/or diagnostic microbial biomarkers. This review also discusses the potential health benefits of the administration of probiotics, prebiotics, postbiotics, and synbiotics and fecal microbiota transplantation in neurological disorders.

Coix Seed Diet Ameliorates Immune Function Disorders in Experimental Colitis Mice

Coix seed is a functional food in the Chinese diet that possesses the ability to alleviate ulcerative colitis clinically. However, the underlying mechanisms remain ambiguous. In this study, we investigated the protective effect of the Coix seed diet on experimental colitis mice. The mice were randomly divided into four groups: control group, model group, Coix seed feed group, and positive control group. The maintenance feed of the mice was replaced with Coix seed feed 10 days before orally administering the mice 5% (w/v) dextran sulfate sodium drink. As a result, the Coix seed feed alleviated colitis symptoms, maintained the complete blood count at a normal level, reduced the pathological score, relieved inflammatory cytokine secretion, and alleviated oxidative stress. Network pharmacology analysis was used for further exploration of the targets of Coix seed feed. The results showed that T-cell regulation is one of the targets of Coix seed feed, and the analysis of the T-lymphocyte subset and innate immune cell distribution of the colon tissue supported the network pharmacology results. In conclusion, Coix seed, as a staple food, can alleviate experimental colitis, and the mechanism may be related to the immune regulation effect of Coix seeds.

The Immune Barrier of Porcine Uterine Mucosa Differs Dramatically at Proliferative and Secretory Phases and Could Be Positively Modulated by Colonizing Microbiota

Endometrial immune response is highly associated with the homeostatic balance of the uterus and embryo development; however, the underlying molecular regulatory mechanisms are not fully elucidated. Herein, the porcine endometrium showed significant variation in mucosal immunity in proliferative and secretory phases by single-cell RNA sequencing. The loose arrangement and high motility of the uterine epithelium in the proliferative phase gave opportunities for epithelial cells and dendritic cells to cross talk with colonizing microbial community, guiding lymphocyte migration into the mucosal and glandular epithelium. The migrating lymphocytes were primarily NK and CD8⁺ T cells, which were robustly modulated by the chemokine signaling. In the secretory phase, the significantly strengthened mechanical mucosal barrier and increased immunoglobulin A alleviated the migration of lymphocytes into the epithelium when the neuro-modulation, mineral uptake, and amino acid metabolism were strongly upregulated. The noticeably increased intraepithelial lymphocytes were positively modulated by the bacteria in the uterine cavity. Our findings illustrated that significant mucosal immunity variation in the endometrium in the proliferative and secretory phases was closely related to intraepithelial lymphocyte migration, which could be modulated by the colonizing bacteria after cross talk with epithelial cells with higher expressions of chemokine.

Nuclear receptors: a bridge linking the gut microbiome and the host

Background

The gut microbiome is the totality of microorganisms, bacteria, viruses, protozoa, and fungi within the gastrointestinal tract. The gut microbiome plays key roles in various physiological and pathological processes through regulating varieties of metabolic factors such as short-chain fatty acids, bile acids and amino acids. Nuclear receptors, as metabolic mediators, act as a series of intermediates between the microbiome and the host and help the microbiome regulate diverse processes in the host. Recently, nuclear receptors such as farnesoid X receptor, peroxisome proliferator-activated receptors, aryl hydrocarbon receptor and vitamin D receptor have been identified as key regulators of the microbiome-host crosstalk. These nuclear receptors regulate metabolic processes, immune activity, autophagy, non-alcoholic and alcoholic fatty liver disease, inflammatory bowel disease, cancer, obesity, and type-2 diabetes.

Conclusion

In this review, we have summarized the functions of the nuclear receptors in the gut microbiome-host axis in different physiological and pathological conditions, indicating that the nuclear receptors may be the good targets for treatment of different diseases through the crosstalk with the gut microbiome.

The Gut-Brain Axis in Multiple Sclerosis. Is Its Dysfunction a Pathological Trigger or a Consequence of the Disease?

A large and expending body of evidence indicates that the gut-brain axis likely plays a crucial role in neurological diseases, including multiple sclerosis (MS). As a whole, the gut-brain axis can be considered as a bi-directional multi-crosstalk pathway that governs the interaction between the gut microbiota and the organism. Perturbation in the commensal microbial population, referred to as dysbiosis, is frequently associated with an increased intestinal permeability, or "leaky gut", which allows the entrance of exogeneous molecules, in particular bacterial products and metabolites, that can disrupt tissue homeostasis and induce inflammation, promoting both local and systemic immune responses. An altered gut microbiota could therefore have significant repercussions not only on immune responses in the gut but also in distal effector immune sites such as the CNS. Indeed, the dysregulation of this bi-directional communication as a consequence of dysbiosis has been implicated as playing a possible role in the pathogenesis of neurological diseases. In multiple sclerosis (MS), the gut-brain axis is increasingly being considered as playing a crucial role in its pathogenesis, with a major focus on specific gut microbiota alterations associated with the disease. In both MS and its purported murine model, experimental autoimmune encephalomyelitis (EAE), gastrointestinal symptoms and/or an altered gut microbiota have been reported together with increased intestinal permeability. In both EAE and MS, specific components of the microbiota have been shown to modulate both effector and regulatory T-cell responses and therefore disease progression, and EAE experiments with germ-free and specific pathogen-free mice transferred with microbiota associated or not with disease have clearly demonstrated the possible role of the microbiota in disease pathogenesis and/or progression. Here, we review the evidence that can point to two possible consequences of the gut-brain axis dysfunction in MS and EAE: 1. A pro-inflammatory intestinal environment and "leaky" gut induced by dysbiosis could lead to an altered communication with the CNS through the cholinergic afferent fibers, thereby contributing to CNS inflammation and disease pathogenesis; and 2. Neuroinflammation affecting efferent cholinergic transmission could result in intestinal inflammation as disease progresses.

Gut-Brain Connection: Microbiome, Gut Barrier, and Environmental Sensors

The gut is an important organ with digestive and immune regulatory function which consistently harbors microbiome ecosystem. The gut microbiome cooperates with the host to regulate the development and function of the immune, metabolic, and nervous systems. It can influence disease processes in the gut as well as extra-intestinal organs, including the brain. The gut closely connects with the central nervous system through dynamic bidirectional communication along the gut-brain axis. The connection between gut environment and brain may affect host mood and behaviors. Disruptions in microbial communities have been implicated in several neurological disorders. A link between the gut microbiota and the brain has long been described, but recent studies have started to reveal the underlying mechanism of the impact of the gut microbiota and gut barrier integrity on the brain and behavior. Here, we summarized the gut barrier environment and the 4 main gut-brain axis pathways. We focused on the important function of gut barrier on neurological diseases such as stress responses and ischemic stroke. Finally, we described the impact of representative environmental sensors generated by gut bacteria on acute neurological disease via the gut-brain axis.

CCDC137 Is a Prognostic Biomarker and Correlates With Immunosuppressive Tumor Microenvironment Based on Pan-Cancer Analysis

Background

The coiled-coil domain containing (CCDC) family proteins have important biological functions in various diseases. However, the coiled-coil domain containing 137 (CCDC137) was rarely studied. We aim to investigate the role of CCDC137 in pan-cancer.

Methods

CCDC137 expression was evaluated in RNA sequence expression profilers of pan-cancer and normal tissues from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) database. The influence of CCDC137 on the prognosis of tumor patients was analyzed using clinical survival data from TCGA. Function and pathway enrichment analysis was performed to explore the role of CCDC137 using the R package “clusterProfiler.” We further analyzed the correlation of immune cell infiltration score of TCGA samples and CCDC137 expression using TIMER2 online database.

Results

CCDC137 was over-expressed and associated with worse survival status in various tumor types. CCDC137 expression was positively correlated with tumor associated macrophages (TAMs) and cancer associated fibroblasts (CAFs) in Lower Grade Glioma (LGG) and Uveal Melanoma (UVM). In addition, high CCDC137 expression was positively correlated with most immunosuppressive genes, including TGFB1, PD-L1, and IL10RB in LGG and UVM.

Conclusions

Our study identified CCDC137 as an oncogene and predictor of worse survival in most tumor types. High CCDC137 may contribute to elevated infiltration of TAMs and CAFs and be associated with tumor immunosuppressive status.

Perturbed Microbiota/Immune Homeostasis in Multiple Sclerosis

Objective

Based on animal models and human studies, there is now strong suspicion that host/microbiota mutualism in the context of gut microbial dysbiosis could influence immunity and multiple sclerosis (MS) evolution. Our goal was to seek evidence of deregulated microbiota-induced systemic immune responses in patients with MS.

Methods

We investigated gut and systemic commensal-specific antibody responses in healthy controls (n = 32), patients with relapsing-remitting MS (n = 30), and individuals with clinically isolated syndromes (CISs) (n = 15). Gut microbiota composition and diversity were compared between controls and patients by analysis of 16S ribosomal ribonucleic acid (rRNA) sequencing. Autologous microbiota and cultivable bacterial strains were used in bacterial flow cytometry assays to quantify autologous serum IgG and secretory IgA responses to microbiota. IgG-bound bacteria were sorted by flow cytometry and identified using 16S rRNA sequencing.

Results

We show that commensal-specific gut IgA responses are drastically reduced in patients with severe MS, disease severity being correlated with the IgA-coated fecal microbiota fraction (r = −0.647, p < 0.0001). At the same time, IgA-unbound bacteria elicit qualitatively broad and quantitatively increased serum IgG responses in patients with MS and CIS compared with controls (4.1% and 2.5% vs 1.9%, respectively, p < 0.001).

Conclusions

Gut and systemic microbiota/immune homeostasis are perturbed in MS. Our results argue that defective IgA responses in MS are linked to a breakdown of systemic tolerance to gut microbiota leading to an enhanced triggering of systemic IgG immunity against gut commensals occurring early in MS.

Bidirectional communication between mast cells and the gut-brain axis in neurodegenerative diseases: Avenues for therapeutic intervention

Although the global incidence of neurodegenerative diseases has been steadily increasing, especially in adults, there are no effective therapeutic interventions. Neurodegeneration is a heterogeneous group of disorders that is characterized by the activation of immune cells in the central nervous system (CNS) (e.g., mast cells and microglia) and subsequent neuroinflammation. Mast cells are found in the brain and the gastrointestinal tract and play a role in "tuning" neuroimmune responses. The complex bidirectional communication between mast cells and gut microbiota coordinates various dynamic neuro-cellular responses, which propagates neuronal impulses from the gastrointestinal tract into the CNS. Numerous inflammatory mediators from degranulated mast cells alter intestinal gut permeability and disrupt blood-brain barrier, which results in the promotion of neuroinflammatory processes leading to neurological disorders, thereby offsetting the balance in immune-surveillance. Emerging evidence supports the hypothesis that gut-microbiota exert a pivotal role in inflammatory signaling through the activation of immune and inflammatory cells. Communication between inflammatory cytokines and neurocircuits via the gut-brain axis (GBA) affects behavioral responses, activates mast cells and microglia that causes neuroinflammation, which is associated with neurological diseases. In this comprehensive review, we focus on what is currently known about mast cells and the gut-brain axis relationship, and how this relationship is connected to neurodegenerative diseases. We hope that further elucidating the bidirectional communication between mast cells and the GBA will not only stimulate future research on neurodegenerative diseases but will also identify new opportunities for therapeutic interventions.

Lactobacillus acidipiscis Induced Regulatory Gamma Delta T Cells and Attenuated Experimental Autoimmune Encephalomyelitis

Multiple sclerosis is a chronic autoimmune disease involving the central nervous system, and shows a high disability rate. Its pathogenesis is complicated, and there is no good treatment. In recent years, with in-depth studies on the regulation of gastrointestinal flora, the relationship between the mammalian immune system and the intestinal flora has been extensively explored. Changes in the composition and structure of the gastrointestinal flora can affect the characteristics and development of the host immune system and even induce a series of central nervous system inflammation events. The occurrence and development of multiple sclerosis are closely related to the continuous destruction of the intestinal barrier caused by intestinal dysbacteriosis. In this study, we analyzed Lactobacillus acidipiscis in a mouse model of experimental autoimmune encephalomyelitis (EAE). We found that the amount of L. acidipiscis in the intestinal tract was inversely proportional to the progress of EAE development. In addition, the number of CD4+ FOXP3+ regulatory T cells in the mesenteric lymph nodes of mice increased significantly after the mice were fed with L. acidipiscis, and the differentiation of CD4+ T cells to Th1 and Th17 cells was inhibited. However, the protective effect of L. acidipiscis was lost in γδ T cell-deficient mice and hence was concluded to depend on the presence of regulatory γδ T cells in the intestinal epithelium. Moreover, including L. acidipiscis enhanced the development of Vγ1+γδ T cells but suppressed that of Vγ4+γδ T cells. In summary, our results demonstrated the ability of L. acidipiscis to induce generation of regulatory γδ T cells that suppress the development of the encephalomyelitic Th1 and Th17 cells and the progress of EAE.

IL10- and IL35-Secreting MutuDC Lines Act in Cooperation to Inhibit Memory T Cell Activation Through LAG-3 Expression

Dendritic cells (DCs) are professional antigen-presenting cells involved in the initiation of immune responses. We generated a tolerogenic DC (tolDC) line that constitutively secretes interleukin-10 (IL10-DCs), expressed lower levels of co-stimulatory and MHCII molecules upon stimulation, and induced antigen-specific proliferation of T cells. Vaccination with IL10-DCs combined with another tolDC line that secretes IL-35, reduced antigen-specific local inflammation in a delayed-type hypersensitivity assay independently on regulatory T cell differentiation. In an autoimmune model of rheumatoid arthritis, vaccination with the combined tolDCs after the onset of the disease impaired disease development and promoted recovery of mice. After stable memory was established, the tolDCs promoted CD4 downregulation and induced lymphocyte activation gene 3 (LAG-3) expression in reactivated memory T cells, reducing T cell activation. Taken together, our findings indicate the benefits of combining anti-inflammatory cytokines in an antigen-specific context to treat excessive inflammation when memory is already established.

The aryl hydrocarbon receptor and the gut-brain axis

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor initially identified as the receptor for dioxin. Almost half a century after its discovery, AHR is now recognized as a receptor for multiple physiological ligands, with important roles in health and disease. In this review, we discuss the role of AHR in the gut-brain axis and its potential value as a therapeutic target for immune-mediated diseases.

Efficacy of probiotics in multiple sclerosis: a systematic review of preclinical trials and meta-analysis of randomized controlled trials

Preliminary evidence shows the potential role of probiotics in ameliorating multiple sclerosis (MS); however, the effects of probiotics on MS remain unclear.

The Role of Gamma-Delta T Cells in Diseases of the Central Nervous System

Gamma-delta (γδ) T cells are a subset of T cells that promote the inflammatory responses of lymphoid and myeloid lineages, and are especially vital to the initial inflammatory and immune responses. Given the capability to connect crux inflammations of adaptive and innate immunity, γδ T cells are responsive to multiple molecular cues and can acquire the capacity to induce various cytokines, such as GM-CSF, IL-4, IL-17, IL-21, IL-22, and IFN-γ. Nevertheless, the exact mechanisms responsible for γδ T cell proinflammatory functions remain poorly understood, particularly in the context of the central nervous system (CNS) diseases. CNS disease, usually leading to irreversible cognitive and physical disability, is becoming a worldwide public health problem. Here, we offer a review of the neuro-inflammatory and immune functions of γδ T cells, intending to understand their roles in CNS diseases, which may be crucial for the development of novel clinical applications.

Contributions of T cells in multiple sclerosis: what do we currently know?

BACKGROUND

Multiple sclerosis (MS) is a complex autoimmune disorder characterized by neurologic dysfunction. The symptoms worsen as the disease progresses to the relapsing stage.

AIM

This study aimed to examine the role of T cells in MS pathogenesis.

MATERIALS AND METHODS

The review was performed based on articles obtained from PsycINFO, PubMed, Web of Science, and CINAHL. Search terms and phrases, such as "multiple sclerosis," "MS," "T cells," "development," "Dysregulated T cells," and "Effector T cells", were used to identify articles that could help explore the research topic.

RESULTS

The pathogenesis of MS is linked to the regulatory, inflammatory, suppressive, and effector roles of T cells. However, the actual roles of specific T cell subsets in MS development are not well understood.

DISCUSSION

The study revealed a significant link between MS and T cell activity. Targeting T cells is a potential strategy for the development of new therapies to manage MS.

CONCLUSION

MS is a complex demyelinating condition that affects several million people around the world. Research has revealed that various classes of T cells, including effector T cells and regulatory T cells, influence the development and progression of MS. Further investigations are required to elucidate the underlying mechanisms through which specific T cell populations influence MS pathogenesis.

LAG-3: from molecular functions to clinical applications

To prevent the destruction of tissues owing to excessive and/or inappropriate immune responses, immune cells are under strict check by various regulatory mechanisms at multiple points. Inhibitory coreceptors, including programmed cell death 1 (PD-1) and cytotoxic T lymphocyte antigen 4 (CTLA-4), serve as critical checkpoints in restricting immune responses against self-tissues and tumor cells. Immune checkpoint inhibitors that block PD-1 and CTLA-4 pathways significantly improved the outcomes of patients with diverse cancer types and have revolutionized cancer treatment. However, response rates to such therapies are rather limited, and immune-related adverse events are also observed in a substantial patient population, leading to the urgent need for novel therapeutics with higher efficacy and lower toxicity. In addition to PD-1 and CTLA-4, a variety of stimulatory and inhibitory coreceptors are involved in the regulation of T cell activation. Such coreceptors are listed as potential drug targets, and the competition to develop novel immunotherapies targeting these coreceptors has been very fierce. Among such coreceptors, lymphocyte activation gene-3 (LAG-3) is expected as the foremost target next to PD-1 in the development of cancer therapy, and multiple clinical trials testing the efficacy of LAG-3-targeted therapy are underway. LAG-3 is a type I transmembrane protein with structural similarities to CD4. Accumulating evidence indicates that LAG-3 is an inhibitory coreceptor and plays pivotal roles in autoimmunity, tumor immunity, and anti-infection immunity. In this review, we summarize the current understanding of LAG-3, ranging from its discovery to clinical application.

Alterations of the gut ecological and functional microenvironment in different stages of multiple sclerosis

We have compared gut microbiomes in the different stages of multiple sclerosis (MS) based on both microbial and functional analyses using fecal samples. Together with microbial composition data, metagenomic functional and metabolite data revealed a reduced level of microbial butyrate and propionate biosynthesis in the gut of relapsing remitting MS (RRMS). On the other hand, in the gut of secondary progressive MS (SPMS), we revealed an enhancement in microbial DNA mismatch repair, which was consistent with excessive fecal oxidation shown in sulfur metabolomic analysis. As elevated oxidative stress is closely associated with chronic neuroinflammation and neurodegeneration, the present result opens a way to microbiome data-assisted management of MS, useful for prevention of disease progression.

Multiple sclerosis (MS), an autoimmune disease of the central nervous system, generally starts as the relapsing remitting form (RRMS), but often shifts into secondary progressive MS (SPMS). SPMS represents a more advanced stage of MS, characterized by accumulating disabilities and refractoriness to medications. The aim of this study was to clarify the microbial and functional differences in gut microbiomes of the different stages of MS. Here, we compared gut microbiomes of patients with RRMS, SPMS, and two closely related disorders with healthy controls (HCs) by 16S rRNA gene and whole metagenomic sequencing data from fecal samples and by fecal metabolites. Each patient group had a number of species having significant changes in abundance in comparison with HCs, including short-chain fatty acid (SCFA)-producing bacteria reduced in MS. Changes in some species had close association with clinical severity of the patients. A marked reduction in butyrate and propionate biosynthesis and corresponding metabolic changes were confirmed in RRMS compared with HCs. Although bacterial composition analysis showed limited differences between the patient groups, metagenomic functional data disclosed an increase in microbial genes involved in DNA mismatch repair in SPMS as compared to RRMS. Together with an increased ratio of cysteine persulfide to cysteine in SPMS revealed by sulfur metabolomics, we postulate that excessive DNA oxidation could take place in the gut of SPMS. Thus, gut ecological and functional microenvironments were significantly altered in the different stages of MS. In particular, reduced SCFA biosynthesis in RRMS and elevated oxidative level in SPMS were characteristic.

Vaginal microbiota, genital inflammation, and neoplasia impact immune checkpoint protein profiles in the cervicovaginal microenvironment

Emerging evidence suggests that the vaginal microbiota play a role in HPV persistence and cervical neoplasia development and progression. Here we examine a broad range of immune checkpoint proteins in the cervicovaginal microenvironment across cervical carcinogenesis and explore relationships among these key immunoregulatory proteins, the microbiota composition, and genital inflammation. First, we demonstrate that immune checkpoint molecules can be measured in cervicovaginal lavages. Secondly, we identify CD40, CD27, and TIM-3 to specifically discriminate cervical cancer from other groups and CD40, CD28, and TLR2 to positively correlate to genital inflammation. Finally, PD-L1 and LAG-3 levels negatively, whereas TLR2 positively correlate to health-associated Lactobacillus dominance. Overall, our study identifies immune checkpoint signatures associated with cervical neoplasm and illuminates the multifaceted microbiota-host immunity network in the local microenvironment. This study provides a foundation for future mechanistic studies and highlights the utility of cervicovaginal lavage profiling for predicting and monitoring response to cancer therapy.

The Gut-CNS Axis in Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune inflammatory disease of the CNS driven by the inflammatory activity of peripheral immune cells recruited to the CNS and by CNS-resident glial cells. MS pathogenesis has been linked to both genetic and environmental factors. In addition, the commensal flora have been shown to modulate immune processes relevant to MS pathogenesis. We discuss the effects of the gut microbiota on T cells and glial cells, and their relevance for the control of inflammation and neurodegeneration in MS. A better understanding of the gut-CNS axis will shed new light on the mechanisms of disease pathogenesis, and may help to guide the development of efficacious therapies for MS.

Dietary natural products as epigenetic modifiers in aging-associated inflammation and disease

Covering: up to 2020Chronic, low-grade inflammation is linked to aging and has been termed "inflammaging". Inflammaging is considered a key contributor to the development of metabolic dysfunction and a broad spectrum of diseases or disorders including declines in brain and heart function. Genome-wide association studies (GWAS) coupled with epigenome-wide association studies (EWAS) have shown the importance of diet in the development of chronic and age-related diseases. Moreover, dietary interventions e.g. caloric restriction can attenuate inflammation to delay and/or prevent these diseases. Common themes in these studies entail the use of phytochemicals (plant-derived compounds) or the production of short chain fatty acids (SCFAs) as epigenetic modifiers of DNA and histone proteins. Epigenetic modifications are dynamically regulated and as such, serve as potential therapeutic targets for the treatment or prevention of age-related disease. In this review, we will focus on the role for natural products that include phytochemicals and short chain fatty acids (SCFAs) as regulators of these epigenetic adaptations. Specifically, we discuss regulators of methylation, acetylation and acylation, in the protection from chronic inflammation driven metabolic dysfunction and deterioration of neurocognitive and cardiac function.

Microbiota and metabolites in rheumatic diseases

As a gigantic community in the human body, the microbiota exerts pleiotropic roles in human health and disease ranging from digestion and absorption of nutrients from food, defense against infection of pathogens, to regulation of immune system development and immune homeostasis. Recent advances in "omics" studies and bioinformatics analyses have broadened our insights of the microbiota composition of the inner and other surfaces of the body and their interactions with the host. Apart from the direct contact of microbes at the mucosal barrier, metabolites produced or metabolized by the gut microbes can serve as important immune regulators or initiators in a wide variety of diseases, including gastrointestinal diseases, metabolic disorders and systemic rheumatic diseases. This review focuses on the most recent understanding of how the microbiota and metabolites shape rheumatic diseases. Studies that explore the mechanistic interplay between microbes, metabolites and the host could thereby provide clues for novel methods in the diagnosis, therapy, and prevention of rheumatic diseases.

Smad7 in intestinal CD4+ T cells determines autoimmunity in a spontaneous model of multiple sclerosis

Environmental triggers acting at the intestinal barrier are thought to contribute to the initiation of autoimmune disorders. The transforming growth factor beta inhibitor Smad7 determines the phenotype of CD4+ T cells. We hypothesized that Smad7 in intestinal CD4+ T cells controls initiation of opticospinal encephalomyelitis (OSE), a murine model of multiple sclerosis (MS), depending on the presence of gut microbiota. Smad7 was overexpressed or deleted in OSE CD4+ T cells to determine the effect on clinical progression, T cell differentiation, and T cell migration from the intestine to the central nervous system (CNS). Smad7 overexpression worsened the clinical course of OSE and increased CNS inflammation and demyelination. It favored expansion of intestinal CD4+ T cells toward an inflammatory phenotype and migration of intestinal CD4+ T cells to the CNS. Intestinal biopsies from MS patients revealed decreased transforming growth factor beta signaling with a shift toward inflammatory T cell subtypes. Smad7 in intestinal T cells might represent a valuable therapeutic target for MS to achieve immunologic tolerance in the intestine and suppress CNS inflammation.

The aryl hydrocarbon receptor: an environmental sensor integrating immune responses in health and disease

The environment, diet, microbiota and body's metabolism shape complex biological processes in health and disease. However, our understanding of the molecular pathways involved in these processes is still limited. The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that integrates environmental, dietary, microbial and metabolic cues to control complex transcriptional programmes in a ligand-specific, cell-type-specific and context-specific manner. In this Review, we summarize our current knowledge of AHR and the transcriptional programmes it controls in the immune system. Finally, we discuss the role of AHR in autoimmune and neoplastic diseases of the central nervous system, with a special focus on the gut immune system, the gut-brain axis and the therapeutic potential of targeting AHR in neurological disorders.

Gut microbiota-dependent CCR9+CD4+ T cells are altered in secondary progressive multiple sclerosis

The mechanism underlying the progression of relapsing-remitting multiple sclerosis to secondary progressive multiple sclerosis (SPMS), characterized by accumulating fixed disability, is yet to be fully understood. Although alterations in the gut microbiota have recently been highlighted in multiple sclerosis pathogenesis, the mechanism linking the altered gut environment with the remote CNS pathology remains unclear. Here, we analyse human CD4⁺ memory T cells expressing the gut-homing chemokine receptor CCR9 and found a reduced frequency of CCR9⁺ memory T cells in the peripheral blood of patients with SPMS relative to healthy controls. The reduction in the proportion of CCR9⁺ cells among CD4⁺ memory T cells (%CCR9) in SPMS did not correlate with age, disease duration or expanded disability status scale score, although %CCR9 decreased linearly with age in healthy controls. During the clinical relapse of both, relapsing-remitting multiple sclerosis and neuromyelitis optica, a high proportion of cells expressing the lymphocyte activating 3 gene (LAG3) was detected among CCR9⁺ memory T cells isolated from the CSF, similar to that observed for mouse regulatory intraepithelial lymphocytes. In healthy individuals, CCR9⁺ memory T cells expressed higher levels of CCR6, a CNS-homing chemokine receptor, and exhibited a regulatory profile characterized by both the expression of C-MAF and the production of IL-4 and IL-10. However, in CCR9⁺ memory T cells, the expression of RORγt was specifically upregulated, and the production of IL-17A and IFNγ was high in patients with SPMS, indicating a loss of regulatory function. The evaluation of other cytokines supported the finding that CCR9⁺ memory T cells acquire a more inflammatory profile in SPMS, reporting similar aspects to CCR9⁺ memory T cells of the elderly healthy controls. CCR9⁺ memory T cell frequency decreased in germ-free mice, whereas antibiotic treatment increased their number in specific pathogen-free conditions. Here, we also demonstrate that CCR9⁺ memory T cells preferentially infiltrate into the inflamed CNS resulting from the initial phase and that they express LAG3 in the late phase in the experimental autoimmune encephalomyelitis mouse model of multiple sclerosis. Antibiotic treatment reduced experimental autoimmune encephalomyelitis symptoms and was accompanied by an increase in CCR9⁺ memory T cells in the peripheral blood. Antibodies against mucosal vascular addressin cell adhesion molecule 1 (MADCAM1), which is capable of blocking cell migration to the gut, also ameliorated experimental autoimmune encephalomyelitis. Overall, we postulate that the alterations in CCR9⁺ memory T cells observed, caused by either the gut microbiota changes or ageing, may lead to the development of SPMS.

Therapeutic potential of aryl hydrocarbon receptor in autoimmunity

Aryl hydrocarbon receptor (AhR), a type of transcriptional factor, is widely expressed in immune cells. The activation of AhR signaling pathway depends on its ligands, which exist in environment and can also be produced by metabolism. Normal expressions of AhR and AhR-mediated signaling may be essential for immune responses, and effects of AhR signaling on the development and function of innate and adaptive immune cells have also been revealed in previous studies. Recent studies also indicate that aberrant AhR signaling may be related to autoimmune diseases, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), multiple sclerosis (MS), autoimmune uveitis (AU), autoimmune diabetes, Behcet's disease (BD) and myasthenia gravis (MG). Moreover, administration of AhR ligands or drugs has been proven effective for improving pathological outcomes in some autoimmune diseases or models. In this review, we summarize the effects of AhR on several innate and adaptive immune cells associated with autoimmunity, and the mechanism on how AhR participates in autoimmune diseases. In addition, we also discuss therapeutic potential and application prospect of AhR in autoimmune diseases, so as to provide valuable information for exploring novel and effective approaches to autoimmune disease treatments.

FETR-ALS Study Protocol: A Randomized Clinical Trial of Fecal Microbiota Transplantation in Amyotrophic Lateral Sclerosis

Background and Rationale: Among the key players in the pathogenesis of Amyotrophic Lateral Sclerosis (ALS), microglia and T regulatory lymphocytes (Treg) are candidate cells for modifying the course of the disease. The gut microbiota (GM) acts by shaping immune tolerance and regulating the Treg number and suppressive function, besides circulating neuropeptides, and other immune cells that play in concert through the gut-brain axis. Previous mouse models have shown an altered enteric flora in early stage ALS, pointing to a possible GM role in ALS pathogenesis. Fecal Microbial Transplantation (FMT) is a well-known therapeutic intervention used to re-establish the proper microenvironment and to modulate enteric and systemic immunity.

Methods: We are going to perform a multicenter randomized double-blind clinical trial employing FMT as a therapeutic intervention for ALS patients (NCT0376632). Forty-two ALS patients, at an early stage, will be enrolled with a 2:1 allocation ratio (28 FMT-treated patients vs. 14 controls). Study duration will be 12 months per patient. Three endoscopic procedures for intestinal biopsies in FMT and control groups are predicted at baseline, month 6 and month 12; at baseline and at month 6 fresh feces from healthy donors will be infused at patients in the intervention arm. The primary outcome is a significant change in Treg number between FMT-treated patients and control arm from baseline to month 6. Secondary outcomes include specific biological aims, involving in-depth analysis of immune cells and inflammatory status changes, central and peripheral biomarkers of ALS, besides comprehensive analysis of the gut, saliva and fecal microbiota. Other secondary aims include validated clinical outcomes of ALS (survival, forced vital capacity, and modifications in ALSFRS-R), besides safety and quality of life.

Expected Results: We await FMT to increase Treg number and suppressive functionality, switching the immune system surrounding motorneurons to an anti-inflammatory, neuroprotective status. Extensive analysis on immune cell populations, cytokines levels, and microbiota (gut, fecal and saliva) will shed light on early processes possibly leading the degenerative ALS course.

Conclusions: This is the first trial with FMT as a potential intervention to modify immunological response to ALS and disease progression at an early stage.

The role of immune regulatory molecules in multiple sclerosis

Multiple sclerosis (MS) is the most common demyelinating disease which mainly impacts the integrity of central nervous system (CNS). MS etiology is not clearly known but genetic, environmental factors and immune system are the most frequently explored risk factors. Adaptive immune responses have a critical role in MS pathogenesis in which auto-reactive T-cells and autoantibodies are main orchestrators. Immune responses are modulated by inhibitory molecules which regulates adaptive system activation and hemostasis interface. These molecules suppress immune responses through inhibition of cytokine secretion and T cell proliferation and subsequently reducing the inflammation and respective damage. Therefore the critical role of inhibitory molecules in regulating the healthy and safe immune responses make them very attractive target for immunotherapy. In this review paper, the role of inhibitory molecules expressed on the various immune cell types in MS pathogenesis and experimental autoimmune encephalomyelitis (EAE) animal model will be summarized.

LAG3: The Biological Processes That Motivate Targeting This Immune Checkpoint Molecule in Human Cancer

The programmed cell death 1 (PD-1) pathway is an important regulator of immune responses in peripheral tissues, including abnormal situations such as the tumor microenvironment. This pathway is currently the principal target for immunotherapeutic compounds designed to block immune checkpoint pathways, with these drugs improving clinical outcomes in a number of solid and hematological tumors. Medical oncology is experiencing an immune revolution that has scientists and clinicians looking at alternative, non-redundant inhibitory pathways also involved in regulating immune responses in cancer. A variety of targets have emerged for combinatorial approaches in immune checkpoint blockade. The main purpose of this narrative review is to summarize the biological role of lymphocyte activation gene 3 (LAG3), an emerging targetable inhibitory immune checkpoint molecule. We briefly discuss its role in infection, autoimmune disease and cancer, with a more detailed analysis of current data on LAG3 expression in breast cancer. Current clinical trials testing soluble LAG3 immunoglobulin and LAG3 antagonists are also presented in this work.

Different Expression Characteristics of LAG3 and PD-1 in Sepsis and Their Synergistic Effect on T Cell Exhaustion: A New Strategy for Immune Checkpoint Blockade

The impairment of immunity characterized by T cell exhaustion is the main cause of death in patients with sepsis after the acute phase. Although PD-1 blockade is highly touted as a promising treatment for improving prognosis, the role of PD-1 plays in sepsis and particularly its different roles in different periods are still very limited. A recent study revealed LAG3 can resist the therapeutic effect of PD-1 blockade in tumor, which inspired us to understand their role in sepsis. We enrolled 26 patients with acute sepsis from 422 candidates using strict inclusion criteria. Follow-up analysis revealed that the expression levels of PD-1 were rapidly increased in the early stage of sepsis but did not change significantly as infection continued (P < 0.05). However, the expression of LAG3 was contrary to that of PD-1. Compared with LAG3 or PD-1 single-positive T cells, T cells coexpressing LAG3 and PD-1 were significantly exhausted (P < 0.05). The proportion of coexpressing T cells was negatively correlated with the total number of lymphocytes (r = −0.653, P = 0.0003) and positively correlated with the SOFA score (r = 0.712, P < 0.0001). In addition, the higher the proportion of coexpressing T cells was, the longer the hospital stay and the higher the mortality. These results showed that LAG3 and PD-1 had a potential synergistic effect in regulating the gradual exhaustion of T cells in sepsis, which seriously affected the clinical prognosis of patients. Therefore, LAG3 and PD-1 double-positive T cells are an important indicator for immunity detection and prognostic evaluation. In the future, precision therapy may pay more attention to the different expression patterns of these two molecules.

The intestinal barrier in multiple sclerosis: implications for pathophysiology and therapeutics

Biological barriers are essential for the maintenance of homeostasis in health and disease. Breakdown of the intestinal barrier is an essential aspect of the pathophysiology of gastrointestinal inflammatory diseases, such as inflammatory bowel disease. A wealth of recent studies has shown that the intestinal microbiome, part of the brain-gut axis, could play a role in the pathophysiology of multiple sclerosis. However, an essential component of this axis, the intestinal barrier, has received much less attention. In this review, we describe the intestinal barrier as the physical and functional zone of interaction between the luminal microbiome and the host. Besides its essential role in the regulation of homeostatic processes, the intestinal barrier contains the gut mucosal immune system, a guardian of the integrity of the intestinal tract and the whole organism. Gastrointestinal disorders with intestinal barrier breakdown show evidence of CNS demyelination, and content of the intestinal microbiome entering into the circulation can impact the functions of CNS microglia. We highlight currently available studies suggesting that there is intestinal barrier dysfunction in multiple sclerosis. Finally, we address the mechanisms by which commonly used disease-modifying drugs in multiple sclerosis could alter the intestinal barrier and the microbiome, and we discuss the potential of barrier-stabilizing strategies, including probiotics and stabilization of tight junctions, as novel therapeutic avenues in multiple sclerosis.

CD4+CD25+LAG3+ T Cells With a Feature of Th17 Cells Associated With Systemic Lupus Erythematosus Disease Activity

Systemic lupus erythematosus (SLE) is an autoimmune disease that involves multiple immune cell subsets. We analyzed immune cell subsets in human peripheral blood mononuclear cells (PBMC) in order to identify the cells that are significantly associated with SLE disease activity and treatment. The frequencies of various subsets of CD4⁺ T cells, B cells, monocytes and NK cells in PBMC were assessed in 30 healthy controls (HC), 30 rheumatoid arthritis (RA) patients and 26 SLE patients using flow cytometry. The correlations between subset frequencies in SLE and clinical traits including Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) were examined. Changes in subset frequencies after the treatment in SLE patients were investigated. We focused on CD25⁺LAG3⁺ T cells and investigated their characteristics, including cytokine secretion, mRNA expression and suppression capacity. We assessed correlations between CD25⁺LAG3⁺ T cells and SLEDAI by Spearman's rank correlation coefficient. CD25⁺LAG3⁺ T cells were significantly increased in SLE whereas there were few in RA and HC groups. CD25⁺LAG3⁺ T cell frequencies were significantly correlated with SLEDAI and were increased in patients with a high SLEDAI score (> 10). CD25⁺LAG3⁺ T cells produced both IL-17 and FOXP3, expressed mRNA of both FOXP3 and RORC and lacked suppressive capacity. CD25⁺LAG3⁺ T cells were associated with disease activity of SLE. CD25⁺LAG3⁺ T cells had features of both CD25⁺FOXP3⁺ regulatory T cells (CD25⁺ Treg) and Th17. CD25⁺LAG3⁺ T cells could be associated with the inflammatory pathophysiology of SLE.

Multiple sclerosis: Possibility of a gut environment-induced disease

Multiple sclerosis is a putative autoimmune disease of the central nervous system, a representative disease of 'neuroimmunology.' We now understand that gut microbiota constitutes an integral part of our body and play critical roles in various neurological diseases with which no intestinal pathology was previously associated. In fact, several reports from Japan, North America, and Europe confirmed dysbiosis of the gut microbiome in MS patients. Given the increase in the prevalence of MS worldwide, especially in Japan, some previously unknown causal environmental factors needed to be identified to inhibit the development of MS in future generations. In this review, we will introduce recent key topics related to MS pathogenesis and immune cells linking gut and brain, and then summarize studies on gut microbiome in MS and its mouse model. Lastly, we will discuss the potential role of diet in the development of MS and propose a hypothesis that could explain the dramatic increase in the number of patients suffering with MS in Japan in the past few decades.