Regulation of CD4+ and CD8+ T Cell Biology by Short-Chain Fatty Acids and Its Relevance for Autoimmune Pathology

The signature of the gut microbiota associated with psoriatic arthritis revealed by metagenomics

Background

Gut microbiota is involved in the development of psoriatic arthritis (PsA), but until now, there has been a lack of understanding of the PsA host-bacteria interaction.

Objectives

To reveal the labels of gut microbiota in PsA patients and the species and functions related to disease activity.

Design

Observational research (cross-sectional) with an exploratory nature.

Methods

Metagenomics sequencing was used to analyze stool samples from 20 treatment-naïve PsA patients and 10 age-matched healthy individuals. All samples were qualified for subsequent analysis.

Results

Compared with the healthy group, α-diversity was reduced in the PsA group, and β-diversity could distinguish the two groups. Two bacteria with high abundance and correlation with PsA disease activity were identified, Bacteroides sp. 3_1_19 and Blautia AF 14-40. In different functions, K07114 (calcium-activated chloride channel (CaCC) homolog) showed a positive correlation with PsA disease activity (disease activity in psoriatic arthritis, DAPSA) and Tet32 (an antibiotic-resistant gene), and carbohydrate-binding module family 50 was negatively correlated with erythrocyte sedimentation rate. A bacterial co-expression network associated with DAPSA was constructed. The network was centered on the bacteria in the Bacteroides genus, which formed a closely related network and were positively correlated with DAPSA. As another core of the network, K07114 was closely related to multiple bacteria in the Bacteroides genus and is also positively correlated with disease activity.

Conclusion

The network composed of Bacteroides is associated with PsA disease activity, and its therapeutic value needs to be further explored. CaCCs may be a key channel for the interaction between Bacteroides and PsA-host.

Role of short-chain fatty acids in host physiology

Short-chain fatty acids (SCFAs) are major metabolites produced by the gut microbiota through the fermentation of dietary fiber, and they have garnered significant attention due to their close association with host health. As important mediators between the gut microbiota and the host, SCFAs serve as energy substrates for intestinal epithelial cells and maintain homeostasis in host immune and energy metabolism by influencing host epigenetics, activating G protein-coupled receptors, and inhibiting pathogenic microbial infections. This review provides a comprehensive summary of SCFAs synthesis and metabolism and offering an overview of the latest research progress on their roles in protecting gut health, enhancing energy metabolism, mitigating diseases such as cancer, obesity, and diabetes, modulating the gut-brain axis and gut-lung axis, and promoting bone health.

Rejuvenating fecal microbiota transplant enhances peripheral nerve repair in aged mice by modulating endoneurial inflammation

Peripheral nerve injury (PNI) resulting from trauma or neuropathies can cause significant disability, and its prognosis deteriorates with age. Emerging evidence suggests that gut dysbiosis and reduced fecal short-chain fatty acids (SCFAs) contribute to an age-related systemic hyperinflammation (inflammaging), which hinders nerve recovery after injury. This study thus aimed to evaluate the pro-regenerative effects of a rejuvenating fecal microbiota transplant (FMT) in a preclinical PNI model using aged mice. Aged C57BL/6 mice underwent bilateral crush injuries to their sciatic nerves. Subsequently, they either received FMT from young donors at three and four days after the injury or retained their aged gut microbiota. We analyzed gut microbiome composition and SCFA concentrations in fecal samples. The integrity of the ileac mucosal barrier was assessed by immunofluorescence staining of Claudin-1. Flow cytometry was utilized to examine immune cells and cytokine production in the ileum, spleen, and sciatic nerve. Various assessments, including behavioural tests, electrophysiological studies, and morphometrical analyses, were conducted to evaluate peripheral nerve function and repair following injury. Rejuvenating FMT reversed age-related gut dysbiosis by increasing Actinobacteria, especially Bifidobacteriales genera. This intervention also led to an elevation of gut SCFA levels and mitigated age-related ileac mucosal leakiness in aged recipients. Additionally, it augmented the number of T-helper 2 (Th2) and regulatory T (Treg) cells in the ileum and spleen, with the majority being positive for anti-inflammatory interleukin-10 (IL-10). In sciatic nerves, rejuvenating FMT resulted in increased M2 macrophage counts and a higher IL-10 production by IL-10+TNF-α- M2 macrophage subsets. Ultimately, restoring a youthful gut microbiome in aged mice led to improved nerve repair and enhanced functional recovery after PNI. Considering that FMT is already a clinically available technique, exploring novel translational strategies targeting the gut microbiome to enhance nerve repair in the elderly seems promising and warrants further evaluation.

Gut microbiota induced epigenetic modifications in the non-alcoholic fatty liver disease pathogenesis

Non-alcoholic fatty liver disease (NAFLD) represents a growing global health concern that can lead to liver disease and cancer. It is characterized by an excessive accumulation of fat in the liver, unrelated to excessive alcohol consumption. Studies indicate that the gut microbiota-host crosstalk may play a causal role in NAFLD pathogenesis, with epigenetic modification serving as a key mechanism for regulating this interaction. In this review, we explore how the interplay between gut microbiota and the host epigenome impacts the development of NAFLD. Specifically, we discuss how gut microbiota-derived factors, such as lipopolysaccharides (LPS) and short-chain fatty acids (SCFAs), can modulate the DNA methylation and histone acetylation of genes associated with NAFLD, subsequently affecting lipid metabolism and immune homeostasis. Although the current literature suggests a link between gut microbiota and NAFLD development, our understanding of the molecular mechanisms and signaling pathways underlying this crosstalk remains limited. Therefore, more comprehensive epigenomic and multi-omic studies, including broader clinical and animal experiments, are needed to further explore the mechanisms linking the gut microbiota to NAFLD-associated genes. These studies are anticipated to improve microbial markers based on epigenetic strategies and provide novel insights into the pathogenesis of NAFLD, ultimately addressing a significant unmet clinical need.

Unravelling the Link between the Gut Microbiome and Autoimmune Kidney Diseases: A Potential New Therapeutic Approach

The gut microbiota and short chain fatty acids (SCFA) have been associated with immune regulation and autoimmune diseases. Autoimmune kidney diseases arise from a loss of tolerance to antigens, often with unclear triggers. In this review, we explore the role of the gut microbiome and how disease, diet, and therapy can alter the gut microbiota consortium. Perturbations in the gut microbiota may systemically induce the translocation of microbiota-derived inflammatory molecules such as liposaccharide (LPS) and other toxins by penetrating the gut epithelial barrier. Once in the blood stream, these pro-inflammatory mediators activate immune cells, which release pro-inflammatory molecules, many of which are antigens in autoimmune diseases. The ratio of gut bacteria Bacteroidetes/Firmicutes is associated with worse outcomes in multiple autoimmune kidney diseases including lupus nephritis, MPO-ANCA vasculitis, and Goodpasture's syndrome. Therapies that enhance SCFA-producing bacteria in the gut have powerful therapeutic potential. Dietary fiber is fermented by gut bacteria which in turn release SCFAs that protect the gut barrier, as well as modulating immune responses towards a tolerogenic anti-inflammatory state. Herein, we describe where the current field of research is and the strategies to harness the gut microbiome as potential therapy.

Disordered GPR43/NLRP3 expression in peripheral leukocytes of patients with atrial fibrillation is associated with intestinal short chain fatty acids levels

BACKGROUND

Atrial fibrillation (AF) is associated with circulating inflammation. Short-chain fatty acids (SCFAs) derived from gut microbiota (GM) regulate leukocyte function and inhibit the release of inflammatory cytokines, which are partly mediated by the G-protein-coupled receptor 43 (GPR43) signaling. This study aimed to investigate the expression of GPR43/NOD-like receptors family pyrin domain containing 3 (NLRP3) in leukocytes and the interaction with intestinal SCFAs levels in AF patients.

METHODS

Expressions of GPR43 and NLRP3 mRNA in peripheral blood leukocytes from 23 AF patients and 25 non-AF controls were detected by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Expressions of leukocyte GPR43 and NLRP3 protein were evaluated by western blot analysis. The levels of plasma IL-1β were measured by enzyme-linked immunosorbent assay (ELISA). The fecal SCFAs levels based on GC/MS metabolome of corresponding 21 controls and 14 AF patients were acquired from our published dataset. To evaluate the expression of NLRP3 and GPR43 and the release of IL-1β, human THP-1 cells were stimulated with or without SCFAs (acetate, propionate, and butyrate), lipopolysaccharide (LPS), and nigericin in vitro, respectively.

RESULTS

Compared to the controls, the mRNA expression in peripheral leukocytes was significantly reduced in AF patients (P = 0.011) coupled with the increase in downstream leukocyte NLRP3 mRNA expression (P = 0.007) and plasma IL-1β levels (P < 0.001), consistent with changes in GPR43 and NLRP3 protein expression. Furthermore, leukocyte GPR43 mRNA levels were positively correlated with fecal GM-derived acetic acid (P = 0.046) and negatively correlated with NLRP3 mRNA expression (P = 0.024). In contrast to the negative correlation between left atrial diameter (LAD) and GPR43 (P = 0.008), LAD was positively correlated with the leukocyte NLRP3 mRNA levels (P = 0.024). Subsequent mediation analysis showed that 68.88% of the total effect of intestinal acetic acid on AF might be mediated by leukocyte GPR43/NLRP3. The constructed GPR43-NLRP3 score might have a predictive potential for AF detection (AUC = 0.81, P < 0.001). Moreover, SCFAs treatment increased GPR43 expression and remarkably reduced LPS/nigericin-induced NLRP3 expression and IL-1β release in human THP-1 cells in vitro.

CONCLUSIONS

Disrupted interactions between GPR43 and NLRP3 expression in peripheral blood leukocytes, associated with reduced intestinal GM-derived SCFAs, especially acetic acid, may be involved in AF development and left atrial enlargement by enhancing circulating inflammation.

Bifidobacterium species viability in dairy-based probiotic foods: challenges and innovative approaches for accurate viability determination and monitoring of probiotic functionality

Bifidobacterium species are essential members of a healthy human gut microbiota. Their presence in the gut is associated with numerous health outcomes such as protection against gastrointestinal tract infections, inflammation, and metabolic diseases. Regular intake of Bifidobacterium in foods is a sustainable way of maintaining the health benefits associated with its use as a probiotic. Owing to their global acceptance, fermented dairy products (particularly yogurt) are considered the ideal probiotic carrier foods. As envisioned in the definition of probiotics as "live organisms," the therapeutic functionalities of Bifidobacterium spp. depend on maintaining their viability in the foods up to the point of consumption. However, sustaining Bifidobacterium spp. viability during the manufacture and shelf-life of fermented dairy products remains challenging. Hence, this paper discusses the significance of viability as a prerequisite for Bifidobacterium spp. probiotic functionality. The paper focuses on the stress factors that influence Bifidobacterium spp. viability during the manufacture and shelf life of yogurt as an archetypical fermented dairy product that is widely accepted as a delivery vehicle for probiotics. It further expounds the Bifidobacterium spp. physiological and genetic stress response mechanisms as well as the methods for viability retention in yogurt, such as microencapsulation, use of oxygen scavenging lactic acid bacterial strains, and stress-protective agents. The report also explores the topic of viability determination as a critical factor in probiotic quality assurance, wherein, the limitations of culture-based enumeration methods, the challenges of species and strain resolution in the presence of lactic acid bacterial starter and probiotic species are discussed. Finally, new developments and potential applications of next-generation viability determination methods such as flow cytometry, propidium monoazide-quantitative polymerase chain reaction (PMA-qPCR), next-generation sequencing, and single-cell Raman spectroscopy (SCRS) methods are examined.

The associations between gut microbiota and inflammatory skin diseases: a bi-directional two-sample Mendelian randomization study

Background

Accumulating evidence shows that dysregulation of intestinal flora is associated with inflammatory skin diseases, specifically atopic dermatitis (AD), psoriasis (PSO), and rosacea (ROS). However, the causality is still unclear.

Objectives

To study the underlying causality between gut microbiota (GM) and AD, PSO, and ROS, a bi-directional two-sample Mendelian randomization (2SMR) analysis was conducted.

Methods

Summary statistics of gut microbiota, AD, PSO, and ROS were extracted from large-scale genome-wide association studies (GWASs). In 2SMR analysis, in addition to the inverse variance weighted as the principal method for evaluating causal association, four different methods were also used. Sensitivity analysis and reverse 2SMR study were implemented to evaluate the robustness of 2SMR results or reverse causal relationship, respectively.

Results

A total of 24 specific gut microbiota species related to AD, PSO, and ROS were identified by 2SMR analysis. After using the Bonferroni method for multiple testing correction, family FamilyXIII (ID: 1957) [OR = 1.28 (1.13, 1.45), p = 9.26e-05] and genus Eubacteriumfissicatenagroup (ID: 14373) [OR = 1.20 (1.09, 1.33), p = 1.65e-04] were associated with an increased risk for AD and PSO, respectively. The genus Dialister showed a negative association, suggesting a protective role against both atopic dermatitis and rosacea. Our reverse 2SMR analysis indicated no reverse causality between these inflammatory skin diseases and the identified gut microbiota.

Conclusions

In summary, this study provided evidence for the causality between GM and inflammatory skin diseases. These findings suggested that supplementing specific bacterial taxa may be an effective therapy for AD, PSO, and ROS.

The Use of Microbial Modifying Therapies to Prevent Psoriasis Exacerbation and Associated Cardiovascular Comorbidity

Psoriasis has emerged as a systemic disease characterized by skin and joint manifestations as well as systemic inflammation and cardiovascular comorbidities. Many progresses have been made in the comprehension of the immunological mechanisms involved in the exacerbation of psoriatic plaques, and initial studies have investigated the mechanisms that lead to extracutaneous disease manifestations, including endothelial disfunction and cardiovascular disease. In the past decade, the involvement of gut dysbiosis in the development of pathologies with inflammatory and autoimmune basis has clearly emerged. More recently, a major role for the skin microbiota in establishing the immunological tolerance in early life and as a source of antigens leading to cross-reactive responses towards self-antigens in adult life has also been evidenced. Gut microbiota can indeed be involved in shaping the immune and inflammatory response at systemic level and in fueling inflammation in the cutaneous and vascular compartments. Here, we summarized the microbiota-mediated mechanisms that, in the skin and gut, may promote and modulate local or systemic inflammation involved in psoriatic disease and endothelial dysfunction. We also analyze the emerging strategies for correcting dysbiosis or modulating skin and gut microbiota composition to integrate systemically existing pharmacological therapies for psoriatic disease. The possibility of merging systemic treatment and tailored microbial modifying therapies could increase the efficacy of the current treatments and potentially lower the effect on patient's life quality.

Mitochondrial and metabolic dysfunction of peripheral immune cells in multiple sclerosis

Multiple sclerosis (MS) is a chronic autoimmune disorder characterized by the infiltration of inflammatory cells and demyelination of nerves. Mitochondrial dysfunction has been implicated in the pathogenesis of MS, as studies have shown abnormalities in mitochondrial activities, metabolism, mitochondrial DNA (mtDNA) levels, and mitochondrial morphology in immune cells of individuals with MS. The presence of mitochondrial dysfunctions in immune cells contributes to immunological dysregulation and neurodegeneration in MS. This review provided a comprehensive overview of mitochondrial dysfunction in immune cells associated with MS, focusing on the potential consequences of mitochondrial metabolic reprogramming on immune function. Current challenges and future directions in the field of immune-metabolic MS and its potential as a therapeutic target were also discussed.

Engineering Strategies to Modulate the Gut Microbiome and Immune System

The gut microbiota, predominantly residing in the colon, is a complex ecosystem with a pivotal role in the host immune system. Dysbiosis of the gut microbiota has been associated with various diseases, and there is an urgent need to develop new therapeutics that target the microbiome and restore immune functions. This Brief Review discusses emerging therapeutic strategies that focus on oral delivery systems for modulating the gut microbiome. These strategies include genetic engineering of probiotics, probiotic-biomaterial hybrids, dietary fibers, and oral delivery systems for microbial metabolites, antimicrobial peptides, RNA, and antibiotics. Engineered oral formulations have demonstrated promising outcomes in reshaping the gut microbiome and influencing immune responses in preclinical studies. By leveraging these approaches, the interplay between the gut microbiota and the immune system can be harnessed for the development of novel therapeutics against cancer, autoimmune disorders, and allergies.

Immunomodulatory effects of inulin and its intestinal metabolites

"Dietary fiber" (DF) refers to a type of carbohydrate that cannot be digested fully. DF is not an essential nutrient, but it plays an important part in enhancing digestive capacity and maintaining intestinal health. Therefore, DF supplementation in the daily diet is highly recommended. Inulin is a soluble DF, and commonly added to foods. Recently, several studies have found that dietary supplementation of inulin can improve metabolic function and regulate intestinal immunity. Inulin is fermented in the colon by the gut microbiota and a series of metabolites is generated. Among these metabolites, short-chain fatty acids provide energy to intestinal epithelial cells and participate in regulating the differentiation of immune cells. Inulin and its intestinal metabolites contribute to host immunity. This review summarizes the effect of inulin and its metabolites on intestinal immunity, and the underlying mechanisms of inulin in preventing diseases such as type 2 diabetes mellitus, inflammatory bowel disease, chronic kidney disease, and certain cancer types.

Nutrients, herbal bioactive derivatives and commensal microbiota as tools to lower the risk of SARS-CoV-2 infection

The SARS-CoV-2 outbreak has infected a vast population across the world, causing more than 664 million cases and 6.7 million deaths by January 2023. Vaccination has been effective in reducing the most critical aftermath of this infection, but some issues are still present regarding re-infection prevention, effectiveness against variants, vaccine hesitancy and worldwide accessibility. Moreover, although several old and new antiviral drugs have been tested, we still lack robust and specific treatment modalities. It appears of utmost importance, facing this continuously growing pandemic, to focus on alternative practices grounded on firm scientific bases. In this article, we aim to outline a rigorous scientific background and propose complementary nutritional tools useful toward containment, and ultimately control, of SARS-CoV-2 infection. In particular, we review the mechanisms of viral entry and discuss the role of polyunsaturated fatty acids derived from α-linolenic acid and other nutrients in preventing the interaction of SARS-CoV-2 with its entry gateways. In a similar way, we analyze in detail the role of herbal-derived pharmacological compounds and specific microbial strains or microbial-derived polypeptides in the prevention of SARS-CoV-2 entry. In addition, we highlight the role of probiotics, nutrients and herbal-derived compounds in stimulating the immunity response.

Immunomodulatory Effects of Microbiota-Derived Short-Chain Fatty Acids in Autoimmune Liver Diseases

Nonpathogenic commensal microbiota and their metabolites and components are essential to maintain a tolerogenic environment and promote beneficial health effects. The metabolic environment critically impacts the outcome of immune responses and likely impacts autoimmune and allergic responses. Short-chain fatty acids (SCFAs) are the main metabolites produced by microbial fermentation in the gut. Given the high concentration of SCFAs in the gut and portal vein and their broad immune regulatory functions, SCFAs significantly influence immune tolerance and gut-liver immunity. Alterations of SCFA-producing bacteria and SCFAs have been identified in a multitude of inflammatory diseases. These data have particular significance in primary biliary cholangitis, primary sclerosing cholangitis, and autoimmune hepatitis because of the close proximity of the liver to the gut. In this focused review, we provide an update on the immunologic consequences of SCFA-producing microbiota and in particular on three dominant SCFAs in autoimmune liver diseases.

Impact of auricular percutaneous electrical nerve field stimulation on gut microbiome in adolescents with irritable bowel syndrome: A pilot study

OBJECTIVES

Percutaneous electrical nerve field stimulation (PENFS) has documented efficacy for irritable bowel syndrome (IBS) via plausible vagal neuromodulation effects. The vagus nerve may affect gut microbiome composition via brain-gut-microbiome signaling. We aimed to investigate gut microbiome alterations by PENFS therapy in adolescent IBS patients.

METHODS

A prospective study of females with IBS aged 11-18 years receiving PENFS therapy for 4 weeks with pre- and post-intervention stool sampling was conducted. Outcome surveys completed pre-therapy, weekly, and post-therapy included IBS-Severity Scoring System (IBS-SSS), Visceral Sensitivity Index (VSI), Functional Disability Inventory (FDI), and the global symptom response scale (SRS). Bacterial DNA was extracted from stool samples followed by 16S rRNA amplification and sequencing. QIIME 2 (version 2022.2) was used for analyses of α and β diversity and differential abundance by group.

RESULTS

Twenty females aged 15.6 ± 1.62 years were included. IBS-SSS, VSI, and FDI scores decreased significantly after PENFS therapy (P < 0.0001, P = 0.0003, P = 0.0004, respectively). No intra- or interindividual microbiome changes were noted pre- versus post-therapy or between responders and non-responders. When response was defined by 50-point IBS-SSS score reduction, α diversity was higher in responders compared with non-responders at week 4 (P = 0.033). There was higher abundance of Blautia in excellent responders versus non-responders.

CONCLUSIONS

There were no substantial microbial diversity alterations with PENFS. Subjects with excellent therapeutic response showed an enrichment of relative abundance of Blautia, which may indicate that patients with specific microbial signature have a more favorable response to PENFS.

Dietary approaches for normalizing dysbiosis induced by high-fat, obesogenic diets

PURPOSE OF REVIEW

Given the world-wide problem of obesity, this review considers what types of dietary changes can be utilized to minimize the adverse effects of an obesogenic diet on the intestinal microbiota.

RECENT FINDINGS

In rodents fed high-fat diets containing lard or Western blend fats to induce obesity, switching to high-fat diets formulated to contain higher amounts of fiber or fiber-containing foods, plant extracts, omega-3 fatty acids or whole grains has beneficial effects on body weight, metabolic alterations, and the intestinal microbiota. Several studies show that the intestinal microbiota has a role in mediating the beneficial health effects of these dietary factors. Many aspects of the microbiota observed in animals when healthful dietary components were added to the feed have also been observed in humans who follow healthful dietary patterns.

SUMMARY

The data shows that specific foods and macronutrients can normalize the obesity-associated microbiota and improve metabolic health. These findings support the design of dietary interventions that would allow individuals to focus on diet quality independently of weight loss to mitigate the adverse sequelae of obesity.

Redefining Autoimmune Disorders' Pathoetiology: Implications for Mood and Psychotic Disorders' Association with Neurodegenerative and Classical Autoimmune Disorders

Although previously restricted to a limited number of medical conditions, there is a growing appreciation that 'autoimmune' (or immune-mediated) processes are important aspects of a wide array of diverse medical conditions, including cancers, neurodegenerative diseases and psychiatric disorders. All of these classes of medical conditions are associated with alterations in mitochondrial function across an array of diverse cell types. Accumulating data indicate the presence of the mitochondrial melatonergic pathway in possibly all body cells, with important consequences for pathways crucial in driving CD8⁺ T cell and B-cell 'autoimmune'-linked processes. Melatonin suppression coupled with the upregulation of oxidative stress suppress PTEN-induced kinase 1 (PINK1)/parkin-driven mitophagy, raising the levels of the major histocompatibility complex (MHC)-1, which underpins the chemoattraction of CD8⁺ T cells and the activation of antibody-producing B-cells. Many factors and processes closely associated with autoimmunity, including gut microbiome/permeability, circadian rhythms, aging, the aryl hydrocarbon receptor, brain-derived neurotrophic factor (BDNF) and its receptor tyrosine receptor kinase B (TrkB) all interact with the mitochondrial melatonergic pathway. A number of future research directions and novel treatment implications are indicated for this wide collection of poorly conceptualized and treated medical presentations. It is proposed that the etiology of many 'autoimmune'/'immune-mediated' disorders should be conceptualized as significantly determined by mitochondrial dysregulation, with alterations in the mitochondrial melatonergic pathway being an important aspect of these pathoetiologies.

The impact of microbiome dysbiosis on T cell function within the tumor microenvironment (TME)

Insights into the effect of the microbiome’s composition on immune cell function have recently been discerned and further characterized. Microbiome dysbiosis can result in functional alterations across immune cells, including those required for innate and adaptive immune responses to malignancies and immunotherapy treatment. Dysbiosis can yield changes in or elimination of metabolite secretions, such as short-chain fatty acids (SCFAs), from certain bacterial species that are believed to impact proper immune cell function. Such alterations within the tumor microenvironment (TME) can significantly affect T cell function and survival necessary for eliminating cancerous cells. Understanding these effects is essential to improve the immune system’s ability to fight malignancies and the subsequent efficacy of immunotherapies that rely on T cells. In this review, we assess typical T cell response to malignancies, classify the known impact of the microbiome and particular metabolites on T cells, discuss how dysbiosis can affect their function in the TME then further describe the impact of the microbiome on T cell-based immunotherapy treatment, with an emphasis on recent developments in the field. Understanding the impact of dysbiosis on T cell function within the TME can carry substantial implications for the design of immunotherapy treatments and further our understanding of factors that could impact how the immune system combats malignancies.

Metabolism and epigenetics at the heart of T cell function

T cell subsets adapt and rewire their metabolism according to their functions and surrounding microenvironment. Whereas naive T cells rely on mitochondrial metabolic pathways characterized by low nutrient requirements, effector T cells induce kinetically faster pathways to generate the biomass and energy needed for proliferation and cytokine production. Recent findings support the concept that alterations in metabolism also affect the epigenetics of T cells. In this review we discuss the connections between T cell metabolism and epigenetic changes such as histone post-translational modifications (PTMs) and DNA methylation, as well as the 'extra-metabolic' roles of metabolic enzymes and molecules. These findings collectively point to a new group of potential therapeutic targets for the treatment of T cell-dependent autoimmune diseases and cancers.

Diet-gut microbial interactions influence cancer immunotherapy

The gut microbiome is involved in the absorption and metabolism of host nutrients and modulates the immune response, affecting the efficacy of immunotherapy for cancer. In patients receiving immunotherapy, appropriate modifications of gut microbiota are thought to improve therapeutic response. Of all the factors that influence the gut microbiota, diet is the most influential and modifiable. Healthy dietary patterns as well as some specific dietary components can help the growth of beneficial microbiota in the gut, thereby protecting against cancers and promoting human health. A growing number of researches have confirmed the positive effects of a diet-gut microbiota approach as an adjuvant therapy for cancer, but controversy remains. Here, we summarize the interactions between diet and gut microbes based on previous studies, and discuss the role of gut microbiota-based dietary strategies in tumor immunotherapy, with the potential mechanisms of actions also intensively discussed.

Crosstalk between the Gut and Brain in Ischemic Stroke: Mechanistic Insights and Therapeutic Options

There has been a significant amount of interest in the past two decades in the study of the evolution of the gut microbiota, its internal and external impacts on the gut, and risk factors for cerebrovascular disorders such as cerebral ischemic stroke. The network of bidirectional communication between gut microorganisms and their host is known as the microbiota-gut-brain axis (MGBA). There is mounting evidence that maintaining gut microbiota homeostasis can frequently enhance the effectiveness of ischemic stroke treatment by modulating immune, metabolic, and inflammatory responses through MGBA. To effectively monitor and cure ischemic stroke, restoring a healthy microbial ecology in the gut may be a critical therapeutic focus. This review highlights mechanistic insights on the MGBA in disease pathophysiology. This review summarizes the role of MGBA signaling in the development of stroke risk factors such as aging, hypertension, obesity, diabetes, and atherosclerosis, as well as changes in the microbiota in experimental or clinical populations. In addition, this review also examines dietary changes, the administration of probiotics and prebiotics, and fecal microbiota transplantation as treatment options for ischemic stroke as potential health benefits. It will become more apparent how the MGBA affects human health and disease with continuing advancements in this emerging field of biomedical sciences.