Metabolic control of regulatory T cell development and function

Role of regulatory T cells in inflammatory liver diseases

The liver is the human body's largest digestive gland, which can participate in digestion, metabolism, excretion, detoxification and immunity. Chronic liver diseases such as metabolic dysfunction-associated fatty liver disease (MAFLD) or viral hepatitis involve ongoing inflammation and resulting liver fibrosis may ultimately lead to the development of hepatobiliary cancers (HCC). Inflammation is the coordinated reaction of different liver cell types to cell signals and death of inflammation, which are linked to injury pathways within the liver or external agents from the gut-liver axis and the circulation. Regulatory T (Treg) cells play a crucial role in controlling inflammation and are essential for maintaining immune tolerance and balance. In this review, we highlight the recent discoveries related to the function of immune systems in liver inflammation and discuss the role of Treg cells in the different liver diseases (including MAFLD, autoimmune hepatitis and others).

Advancements in the study of short-chain fatty acids and their therapeutic effects on atherosclerosis

Atherosclerosis (AS) remains a leading cause of cardiovascular disease and mortality globally. This chronic condition is characterized by inflammation, lipid accumulation, and the deposition of cellular components within arterial walls. Emerging evidence has highlighted the multifaceted therapeutic potential of short-chain fatty acids (SCFAs) in mitigating AS progression. SCFAs have demonstrated anti-inflammatory properties and the ability to regulate immune responses, metabolic pathways, vascular integrity, and intestinal barrier function in animal models of AS. Consequently, SCFAs have garnered significant attention as a promising approach for the prevention and treatment of AS. However, further clinical trials and studies are necessary to fully elucidate the underlying mechanisms and effects of SCFAs. Additionally, different types of SCFAs may exert distinct impacts, necessitating more in-depth investigation into their specific roles and mechanisms. This review provides an overview of the diverse cellular mechanisms contributing to AS formation, as well as a discussion of the significance of SCFAs in AS pathogenesis and their multifaceted therapeutic potential. Nonetheless, additional research is warranted to comprehensively understand and harness the potential of various SCFAs in the context of AS.

Regulatory T Cells in Tumor Microenvironment: Therapeutic Approaches and Clinical Implications

Regulatory T cells (Tregs), previously referred to as suppressor T cells, represent a distinct subset of CD4+ T cells that are uniquely specialized for immune suppression. They are characterized by the constitutive expression of the transcription factor FoxP3 in their nuclei, along with CD25 (the IL-2 receptor α-chain) and CTLA-4 on their cell surface. Tregs not only restrict natural killer cell-mediated cytotoxicity but also inhibit the proliferation of CD4+ and CD8+ T-cells and suppress interferon-γ secretion by immune cells, ultimately impairing an effective antitumor immune response. Treg cells are widely recognized as a significant barrier to the effectiveness of tumor immunotherapy in clinical settings. Extensive research has consistently shown that Treg cells play a pivotal role in facilitating tumor initiation and progression. Conversely, the depletion of Treg cells has been linked to a marked delay in tumor growth and development.

Exploring the Gut Microbiota-Retina Axis: Implications for Health and Disease

The gut microbiota represents a rich and adaptive microbial network inhabiting the gastrointestinal tract, performing key functions in nutrient processing, immune response modulation, intestinal wall protection, and microbial defense. Its composition remains highly personalized and responsive to external influences, including lifestyle patterns, physical activity, body composition, and nutritional intake. The interactions of the gut microbiota with bodily systems are conventionally interpreted as broad systemic impacts on organ balance. Yet, emerging research-exemplified by the gut microbiota-brain axis-suggests the potential existence of more targeted and direct communication mechanisms. Dysbiosis, characterized by microbial ecosystem disturbance, generates multiple metabolic compounds capable of entering systemic circulation and reaching distant tissues, notably including ocular structures. This microbial imbalance has been associated with both systemic and localized conditions linked to eye disorders. Accumulating scientific evidence now supports the concept of a gut-retina axis, underscoring the significant role of microbiota disruption in generating various retinal pathologies. This review comprehensively investigates gut microbiota composition, functional dynamics, and dysbiosis-induced alterations, with specific focus on retinal interactions in age-related macular degeneration, diabetic retinopathy, glaucoma, and retinal artery occlusion. Moreover, the review explores microbiota-targeted therapeutic strategies, including precision nutritional interventions and microbial transplantation, as potential modulators of retinal disease progression.

HIF-1α-Induced GPR171 Expression Mediates CCL2 Secretion by Mast Cells to Promote Gastric Inflammation During Helicobacter pylori Infection

BACKGROUND

Helicobacter pylori (H. pylori) infection is one of the most important risk factors for chronic gastritis, gastric ulcers, and gastric cancer. Mast cells act as a crucial regulator in bacterial infection. The mechanisms underlying mast cell activation and their role in H. pylori infection remain poorly understood.

MATERIALS AND METHODS

In gastric mucosal tissue, the number of mast cells, G-protein-coupled receptor 171 (GPR171) and CCL2 expression were detected by immunohistochemistry (IHC) or immunofluorescence between H. pylori-negative and H. pylori-positive patients. Mast cells were co-cultured with H. pylori, and transcriptome sequencing, RT-qPCR, and Western blotting (WB) were performed to identify receptors involved in mast cell activation. WB, chromatin immunoprecipitation (ChIP), and dual-luciferase reporter assays were conducted to investigate the molecular mechanism by which HIF-1α regulates GPR171 expression. Lentiviral knockdown, ELISA, WB, and IHC were used to evaluate the role of GPR171 during H. pylori infection. An in vivo mouse model of H. pylori infection was employed to assess the effects of GPR171 blockade on CCL2 expression and gastric mucosal inflammation.

RESULTS

In the study, we found that mast cell numbers were greatly increased and correlated with the severity of inflammation in H. pylori-infected patients. We found a new receptor, GPR171, was upregulated and involved in mast cell activation upon H. pylori infection. Furthermore, H. pylori infection induced the expression of GPR171 by promoting the activation of hypoxia-inducible factor 1 alpha (HIF-1α), which directly bound to hypoxia response elements in the GPR171 promoter and regulated its transcriptional activity. Blockade or loss of GPR171 in mast cells partially inhibited CCL2 secretion via the ERK1/2 signaling pathway. In the human gastric mucosa, CCL2 derived from mast cells was associated with gastric inflammation during H. pylori infection. In vivo murine studies indicated that H. pylori infection significantly upregulated CCL2 expression, while GPR171 inhibition partially reduced CCL2 levels and alleviated gastric mucosal inflammation.

CONCLUSIONS

We provide a novel mechanism that H. pylori activates mast cells to promote gastric inflammation.

Total ginsenosides from wild ginseng improve immune regulation in a rat model of spleen qi deficiency by modulating fecal-bacteria-associated short-chain fatty acids and intestinal barrier integrity

For thousands of years, traditional Chinese medicine (TCM) has made extensive use of wild ginseng. It is thought to provide vital energy effects and to boost immunity. This study aimed to clarify the processes by which short-chain fatty acids (SCFAs) metabolites and the intestinal barrier are used by total ginsenosides wild ginseng (TWG) to modulate immunity. In this study, we analyzed and identified ginsenosides in the colon using UPLC-Q-TOF-MSE methods. In the meantime, a rat model of spleen qi deficiency (SQD) was created using reserpine, and the effects of TWG on intestinal barrier function and short-chain fatty acids in the feces of SQD-affected rats were examined. 28 ginsenosides were found in the colon during this experiment, and the main components were measured. TWG considerably increased fecal concentrations of acetic, propionic and 6 others, according to SCFAs analysis. According to serum immunological markers, TWG reduced IL-17 and IL-1β levels, increased IL-10, IL-22, and TGF-β concentrations, balanced Th17/Treg ratios, and reduced toxicants such DAO and LPS in rats with SQD. TWG improved barrier function, reduced permeability, increased tight junction protein expression, and lessened intestinal injury. A favorable correlation between intestinal barrier proteins and fatty acids was shown by correlation studies. The gut barrier and SCFAs perspectives helped to clarify the mechanism by which TWG controls immune activity. This study offers a fresh theoretical framework for TWG's future advancement and application.

KLHL25-ACLY module functions as a switch in the fate determination of the differentiation of iTreg/Th17

The differentiation of Th17 and iTreg is tightly associated with fatty acid metabolism. TGFβ1-induced iTreg differentiation from Th0 relies on fatty acid oxidation (FAO), whereas IL-6 with TGFβ1 shifts metabolism to Th17-preferred fatty acid synthesis (FAS). However, how IL-6 reprograms fatty acid metabolism remains unclear. Here, we unveiled that TGFβ1-activated JNK is recruited to the Klhl25 promoter by NF-YA. JNK then phosphorylates histone H3 at Ser10 to activate Klhl25 transcription, leading to the ubiquitination-dependent degradation of ATP-citrate lyase (ACLY) and the switch from FAS to FAO, which supports iTreg generation. Whereas, upon IL-6 signaling, NF-YA is phosphorylated by ERK, losing its DNA binding ability, which shuts off TGFβ1-JNK-mediated Klhl25 transcription and ACLY ubiquitination, thereby increasing FAS and supporting Th17 differentiation. This study demonstrated that KLHL25-ACLY module functions as a switch in response to TGFβ1 and IL-6 signals, playing a decisive role in the fate determination of iTreg/Th17 differentiation.

Association Between Altered Microbiota Composition and Immune System-Related Genes in COVID-19 Infection

Microbiota and immunity affect the host's susceptibility to SARS-CoV-2 infection and the severity of COVID-19. This study aimed to identify significant alterations in the microbiota composition, immune signaling pathways, their potential association, and candidate microRNA in COVID-19 patients using an in silico study model. Enrichment online databases and Python programming were utilized to analyze GSE164805, GSE180594, and GSE182279, as well as NGS data of microbiota composition (PRJNA650244 and PRJNA660302) associated with COVID-19, employing amplicon-based/marker gene sequencing methods. C1, TNF, C2, IL1, and CFH genes were found to have a significant impact on immune signaling pathways. Additionally, we observed a notable decrease in Bacteroides spp. and Faecalibacterium sp., while Escherichia coli, Streptococcus spp., and Akkermansia muciniphila showed increased abundance in COVID-19. Notably, A. muciniphila demonstrated an association with immunity through C1 and TNF, while Faecalibacterium sp. was linked to C2 and IL1. The correlation between E. coli and CFH, as well as IL1 and Streptococcus spp. with C2, was identified. hsa-let-7b-5p was identified as a potential candidate that may be involved in the interaction between the microbiota composition, immune response, and COVID-19. In conclusion, integrative in silico analysis shows that these microbiota members are potentially crucial in the immune responses against COVID-19.

Sphingosine-1-Phosphate Signalling Inhibition Suppresses Th1-Like Treg Generation by Reversing Mitochondrial Uncoupling

Inflammatory environments induce the generation of dysfunctional IFNγ+T-bet+FOXP3+ Th1-like Tregs, which show defective function and are found in autoimmune conditions including multiple sclerosis (MS). The pathways that control the generation of Th1-like Tregs are not well understood. Sphingosine-1-phosphate (S1P) signalling molecules are upregulated in Th1-like Tregs, and in vivo S1P inhibition with Fingolimod (FTY720) inhibits the expression of genes responsible for Treg plasticity in MS patients. However, the underlying mechanisms are unknown. Here we show that S1P signalling inhibition by FTY720 inhibits the generation of Th1-like Tregs and rescues their suppressive function. These effects are mediated by a decrease in mTORC1 signalling and reversal of the mitochondrial uncoupling that Tregs undergo during their reprogramming into Th1-like Tregs in vitro. Finally, these results are validated in in vivo-generated Th1-like Tregs, as Tregs from MS patients treated with FTY720 display decreased Th1-like Treg frequency, increased suppressive function and mitochondrial metabolism rebalance. These results highlight the involvement of mitochondrial uncoupling in Treg reprogramming and identify S1P signalling inhibition as a target to suppress the generation of dysfunctional Th1-like Tregs.

Metabolic reprogramming and therapeutic resistance in primary and metastatic breast cancer

Metabolic alterations, a hallmark of cancer, enable tumor cells to adapt to their environment by modulating glucose, lipid, and amino acid metabolism, which fuels rapid growth and contributes to treatment resistance. In primary breast cancer, metabolic shifts such as the Warburg effect and enhanced lipid synthesis are closely linked to chemotherapy failure. Similarly, metastatic lesions often display distinct metabolic profiles that not only sustain tumor growth but also confer resistance to targeted therapies and immunotherapies. The review emphasizes two major aspects: the mechanisms driving metabolic resistance in both primary and metastatic breast cancer, and how the unique metabolic environments in metastatic sites further complicate treatment. By targeting distinct metabolic vulnerabilities at both the primary and metastatic stages, new strategies could improve the efficacy of existing therapies and provide better outcomes for breast cancer patients.

Complex Interplay Between Metabolism and CD4+ T-Cell Activation, Differentiation, and Function: a Novel Perspective for Atherosclerosis Immunotherapy

Atherosclerosis is a complex pathological process that results from the chronic inflammatory reaction of the blood vessel wall and involves various immune cells and cytokines. An imbalance in the proportion and function of the effector CD4+ T-cell (Teff) and regulatory T-cell (Treg) subsets is an important cause of the occurrence and development of atherosclerotic plaques. Teff cells depend on glycolytic metabolism and glutamine catabolic metabolism for energy, while Treg cells mainly rely on fatty acid oxidation (FAO), which is crucial for determining the fate of CD4+ T cells during differentiation and maintaining their respective immune functions. Here, we review recent research achievements in the field of immunometabolism related to CD4+ T cells, focusing on the cellular metabolic pathways and metabolic reprogramming involved in the activation, proliferation, and differentiation of CD4+ T cells. Subsequently, we discuss the important roles of mTOR and AMPK signaling in regulating CD4+ T-cell differentiation. Finally, we evaluated the links between CD4+ T-cell metabolism and atherosclerosis, highlighting the potential of targeted modulation of CD4+ T-cell metabolism in the prevention and treatment of atherosclerosis in the future.

The gut-eye axis: the retinal/ocular degenerative diseases and the emergent therapeutic strategies

The interplay between human microbiota and various physiological systems has garnered significant attention in recent years. The gut microbiota plays a critical role in maintaining physiological homeostasis and influences various aspects of human health, particularly via the gut brain axis. Since 2017, the challenging concept of the gut-retina axis has emerged thanks to a network analysis emphasizing the potential role of the gut microbiota disruption in the development of the age-related macular degeneration and further retinal damages. Many other ocular disorders have been linked to the dysbiosis of the gut microbiota, including uveitis and glaucoma. It has been shown that age related macular degeneration can be prevented or reversed using a diet that induces changes in the gut microbiota. The potential link between the gut microbiota as well as others types of microbiota such as the ocular surface microbiota and the development/progression of age related as well as inherited retinal degenerations and other degenerative eye diseases, has recently been broadened. Therefore, the pathogenesis of several eye diseases has recently been associated with a larger perception called the gut eye axis. This mini-review examines the potential mechanisms underlying the gut eye axis and suggests implications for the management of eye diseases. By understanding the modulation of the gut microbiota and its impact on eye disease, this mini-review provides insight into potential therapeutic interventions and avenues for future research.

Baseline Gut Microbiota Was Associated with Long-Term Immune Response at One Year Following Three Doses of BNT162b2

BACKGROUND

This study explored neutralizing IgG antibody levels against COVID-19 decline over time post-vaccination. We conducted this prospective cohort study to investigate the function of gut microbiota in the host immune response following three doses of BNT162b2.

METHODS

Subjects who received three doses of BNT162b2 were recruited from three centers in Hong Kong. Blood samples were obtained before the first dose and at the one-year timepoint for IgG ELISA to determine the level of neutralizing antibody (NAb). The primary outcome was a high immune response (NAb > 600 AU/mL). We performed shotgun DNA metagenomic sequencing on baseline fecal samples to identify bacterial species and metabolic pathways associated with high immune response using linear discriminant analysis effect size analysis.

RESULTS

A total of 125 subjects were recruited (median age: 52 years [IQR: 46.2-59.0]; male: 43 [34.4%]), and 20 were regarded as low responders at the one-year timepoint. Streptococcus parasanguinis (log10LDA score = 2.38, p = 0.003; relative abundance of 2.97 × 10-5 vs. 0.03%, p = 0.001), Bacteroides stercoris (log10LDA score = 4.29, p = 0.024; relative abundance of 0.14% vs. 2.40%, p = 0.014) and Haemophilus parainfluenzae (log10LDA score = 2.15, p = 0.022; relative abundance of 0.01% vs. 0, p = 0.010) were enriched in low responders. Bifidobacterium pseudocatenulatum (log10LDA score = 2.99, p = 0.048; relative abundance of 0.09% vs. 0.36%, p = 0.049) and Clostridium leptum (log10LDA score = 2.38, p = 0.014; relative abundance of 1.2 × 10-5% vs. 0, p = 0.044) were enriched in high responders. S. parasanguinis was negatively correlated with the superpathway of pyrimidine ribonucleotides de novo biosynthesis (log10LDA score = 2.63), which contributes to inflammation and antibody production. H. parainfluenzae was positively correlated with pathways related to anti-inflammatory processes, including the superpathway of histidine, purine, and pyrimidine biosynthesis (log10LDA score = 2.14).

CONCLUSION

Among three-dose BNT162b2 recipients, S. parasanguinis, B. stercoris and H. parainfluenzae were associated with poorer immunogenicity at one year, while B. pseudocatenulatum and C. leptum was associated with a better response.

Oral administration of RDP58 ameliorated DSS-induced colitis in intestinal microbiota dependent manner

BACKGROUND

Although the pathogenesis of inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), has not been fully elucidated, accumulating researches suggest that intestinal microbiota imbalance contributes to the development of IBD in patients and animal models. RDP58, a peptide-based computer-assisted rational design, has been demonstrated to be effective in protecting against a wide range of autoimmune and inflammatory diseases. However, the underlying mechanism by which RDP58 protects against IBD mediated by intestinal microbiota has yet to be elucidated.

METHODS

The colitis model was induced by continuously administering 2.5 % (wt/vol) dextran sodium sulfate (DSS) solution for 7 days. The manifestations of colon inflammation were assessed via daily weight changes, colon length, tumor necrosis factor-alpha (TNF-α) level, disease activity index (DAI) score, pathology score, and intestinal barrier permeability. Intestinal microbiota analysis was carried out by 16S-rRNA sequencing. Colonic short chain fatty acids (SCFAs) and regulatory T cells (Tregs) were also detected. To further confirm the protective effect of RDP58 on intestinal microbiota, broad-spectrum antibiotic cocktail (ABX) treatment and fecal microbial transplantation (FMT) experiment were performed.

RESULTS

Oral administration of RDP58 ameliorated DSS-induced mice colitis by altering the diversity and composition of intestinal microbiota. Notably, RDP58 significantly upregulated SCFAs-producing microbiota, thereby promoting the generation of Tregs. ABX and FMT were performed to verify the above mechanism.

CONCLUSIONS

RDP58 ameliorated DSS-induced colitis through altering intestinal microbiota and enhancing SCFAs and Tregs production in intestinal microbiota dependent manner, potentially provide a novel therapy for IBD.

Re-establishing immune tolerance in multiple sclerosis: focusing on novel mechanisms of mesenchymal stem cell regulation of Th17/Treg balance

The T-helper 17 (Th17) cell and regulatory T cell (Treg) axis plays a crucial role in the development of multiple sclerosis (MS), which is regarded as an immune imbalance between pro-inflammatory cytokines and the maintenance of immune tolerance. Mesenchymal stem cell (MSC)-mediated therapies have received increasing attention in MS research. In MS and its animal model experimental autoimmune encephalomyelitis, MSC injection was shown to alter the differentiation of CD4+T cells. This alteration occurred by inducing anergy and reduction in the number of Th17 cells, stimulating the polarization of antigen-specific Treg to reverse the imbalance of the Th17/Treg axis, reducing the inflammatory cascade response and demyelination, and restoring an overall state of immune tolerance. In this review, we summarize the mechanisms by which MSCs regulate the balance between Th17 cells and Tregs, including extracellular vesicles, mitochondrial transfer, metabolic reprogramming, and autophagy. We aimed to identify new targets for MS treatment using cellular therapy by analyzing MSC-mediated Th17-to-Treg polarization.

Gut-derived immune cells and the gut-lung axis in ARDS

The gut serves as a vital immunological organ orchestrating immune responses and influencing distant mucosal sites, notably the respiratory mucosa. It is increasingly recognized as a central driver of critical illnesses, with intestinal hyperpermeability facilitating bacterial translocation, systemic inflammation, and organ damage. The "gut-lung" axis emerges as a pivotal pathway, where gut-derived injurious factors trigger acute lung injury (ALI) through the systemic circulation. Direct and indirect effects of gut microbiota significantly impact immune responses. Dysbiosis, particularly intestinal dysbiosis, termed as an imbalance of microbial species and a reduction in microbial diversity within certain bodily microbiomes, influences adaptive immune responses, including differentiating T regulatory cells (Tregs) and T helper 17 (Th17) cells, which are critical in various lung inflammatory conditions. Additionally, gut and bone marrow immune cells impact pulmonary immune activity, underscoring the complex gut-lung interplay. Moreover, lung microbiota alterations are implicated in diverse gut pathologies, affecting local and systemic immune landscapes. Notably, lung dysbiosis can reciprocally influence gut microbiota composition, indicating bidirectional gut-lung communication. In this review, we investigate the pathophysiology of ALI/acute respiratory distress syndrome (ARDS), elucidating the role of immune cells in the gut-lung axis based on recent experimental and clinical research. This exploration aims to enhance understanding of ALI/ARDS pathogenesis and to underscore the significance of gut-lung interactions in respiratory diseases.

B and T cells: (Still) the dominant orchestrators in autoimmune hepatitis

Autoimmune hepatitis (AIH) is a severe hepatopathy characterized by hypergammaglobulinemia, presence of serum autoantibodies and histological appearance of interface hepatitis. Liver damage in AIH is initiated by the presentation of a liver autoantigen to uncommitted Th0 lymphocytes, followed by a cascade of effector immune responses culminating with the production of inflammatory cytokines, activation of cytotoxic cells and subsequent hepatocyte injury. B cells actively participate in AIH liver damage by presenting autoantigens to uncommitted T lymphocytes. B cells also undergo maturation into plasma cells that are responsible for production of immunoglobulin G and autoantibodies, which mediate antibody dependent cell cytotoxicity. Perpetuation of effector immunity with consequent progression of liver damage is permitted by impairment in regulatory T cells (Tregs), a lymphocyte subset central to the maintenance of immune homeostasis. Treg impairment in AIH is multifactorial, deriving from numerical decrease, reduced suppressive function, poor response to IL-2 and less stable phenotype. In this review, we discuss the role of B and T lymphocytes in the pathogenesis of AIH. Immunotherapeutic strategies that could limit inflammation and halt disease progression while reconstituting tolerance to liver autoantigens are also reviewed and discussed.

Role of gut-liver axis and glucagon-like peptide-1 receptor agonists in the treatment of metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a hepatic manifestation of the metabolic syndrome. It is one of the most common liver diseases worldwide and shows increasing prevalence rates in most countries. MAFLD is a progressive disease with the most severe cases presenting as advanced fibrosis or cirrhosis with an increased risk of hepatocellular carcinoma. Gut microbiota play a significant role in the pathogenesis and progression of MAFLD by disrupting the gut-liver axis. The mechanisms involved in maintaining gut-liver axis homeostasis are complex. One critical aspect involves preserving an appropriate intestinal barrier permeability and levels of intestinal lumen metabolites to ensure gut-liver axis functionality. An increase in intestinal barrier permeability induces metabolic endotoxemia that leads to steatohepatitis. Moreover, alterations in the absorption of various metabolites can affect liver metabolism and induce liver steatosis and fibrosis. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are a class of drugs developed for the treatment of type 2 diabetes mellitus. They are also commonly used to combat obesity and have been proven to be effective in reversing hepatic steatosis. The mechanisms reported to be involved in this effect include an improved regulation of glycemia, reduced lipid synthesis, β-oxidation of free fatty acids, and induction of autophagy in hepatic cells. Recently, multiple peptide receptor agonists have been introduced and are expected to increase the effectiveness of the treatment. A modulation of gut microbiota has also been observed with the use of these drugs that may contribute to the amelioration of MAFLD. This review presents the current understanding of the role of the gut-liver axis in the development of MAFLD and use of members of the GLP-1 RA family as pleiotropic agents in the treatment of MAFLD.

Stachyose Exerts Anticolitis Efficacy by Re-balancing Treg/Th17 and Activating the Butyrate-Derived PPARγ Signaling Pathway

Ulcerative colitis (UC) is a complex chronic inflammatory disease closely associated with gut homeostasis dysfunction. The previous studies have shown that stachyose, a functional food additive, has the potential to enhance gut health and alleviate UC symptoms. However, the underlying mechanism of its effects remains unknown. In this study, our findings showed that dietary supplements of stachyose had a significant dose-dependent protective effect on colitis symptoms, regulation of gut microbiota, and restoration of the Treg/Th17 cell balance in dextran sulfate sodium (DSS) induced colitis mice. To further validate these findings, we conducted fecal microbiota transplantation (FMT) to treat DSS-induced colitis in mice. The results showed that microbiota from stachyose-treated mice exhibited a superior therapeutic effect against colitis and effectively regulated the Treg/Th17 cell balance in comparison to the control group. Moreover, both stachyose supplementation and FMT resulted in an increase in butyrate production and the activation of PPARγ. However, this effect was partially attenuated by PPARγ antagonist GW9662. These results suggested that stachyose alleviates UC symptoms by modulating gut microbiota and activating PPARγ. In conclusion, our work offers new insights into the benefical effects of stachyose on UC and its potential role in modulating gut microbiota.

The Molecular Mechanisms Underlying the Systemic Effects Mediated by Parathormone in the Context of Chronic Kidney Disease

Chronic kidney disease (CKD) stands as a prominent non-communicable ailment, significantly impacting life expectancy. Physiopathology stands mainly upon the triangle represented by parathormone-Vitamin D-Fibroblast Growth Factor-23. Parathormone (PTH), the key hormone in mineral homeostasis, is one of the less easily modifiable parameters in CKD; however, it stands as a significant marker for assessing the risk of complications. The updated "trade-off hypothesis" reveals that levels of PTH spike out of the normal range as early as stage G2 CKD, advancing it as a possible determinant of systemic damage. The present review aims to review the effects exhibited by PTH on several organs while linking the molecular mechanisms to the observed actions in the context of CKD. From a diagnostic perspective, PTH is the most reliable and accessible biochemical marker in CKD, but its trend bears a higher significance on a patient's prognosis rather than the absolute value. Classically, PTH acts in a dichotomous manner on bone tissue, maintaining a balance between formation and resorption. Under the uremic conditions of advanced CKD, the altered intestinal microbiota majorly tips the balance towards bone lysis. Probiotic treatment has proven reliable in animal models, but in humans, data are limited. Regarding bone status, persistently high levels of PTH determine a reduction in mineral density and a concurrent increase in fracture risk. Pharmacological manipulation of serum PTH requires appropriate patient selection and monitoring since dangerously low levels of PTH may completely inhibit bone turnover. Moreover, the altered mineral balance extends to the cardiovascular system, promoting vascular calcifications. Lastly, the involvement of PTH in the Renin-Angiotensin-Aldosterone axis highlights the importance of opting for the appropriate pharmacological agent should hypertension develop.

Metabolic imbalance driving immune cell phenotype switching in autoimmune disorders: Tipping the balance of T- and B-cell interactions

The interplay between the immune system and the metabolic state of a cell is intricate. In all phases of an immune response, the corresponding metabolic changes shall occur to support its modulation, in addition to the signalling through the cytokine environment and immune receptor stimulation. While autoimmune disorders may develop because of a metabolic imbalance that modulates switching between T-cell phenotypes, the effects that the interaction between T and B cells have on one another's cellular metabolism are yet to be understood in disease context. Here, we propose a perspective which highlights the potential of targeting metabolism to modulate T- and B-cell subtypes populations as well as T-B and B-T cell interactions to successfully treat autoimmune disorders. Specifically, we envision how metabolic changes can tip the balance of immune cells interactions, through definite mechanisms in both health and disease, to explain phenotype switches of B and T cells. Within this scenario, we highlight targeting metabolism that link inflammation, immunometabolism, epigenetics and ageing, is critical to understand inflammatory disorders. The combination of treatments targeting immune cells that cause (T/B) cell phenotype imbalances, and the metabolic pathways involved, may increase the effectiveness of treatment of autoimmune disorders, and/or ameliorate their symptoms to improve patients' quality of life.

Microbiota and Lipotoxicity

Gut microbiota is an indispensable commensal partner of human superorganism. The wealth of genetic repertoire provided by these microorganisms extends host's substrate processing capability. Energy and nutrient harvesting machinery primarily depends on the proper function of these organisms. However, the dynamic composition of microbiota changes with age, lifestyle, stress factors, infections, medications, and host pathophysiological conditions. Host immune system is primarily responsible for shaping up the microbial community and sustaining the symbiotic state. This involves controlling the delicate balance between agility toward pathobionts and tolerance toward symbionts. When things go wrong with this crosstalk, dysbiosis may arise.Metabolic syndrome is a multisystemic, low-grade chronic inflammatory disease that involves dyslipidemia, glucose intolerance, insulin resistance, and central obesity. Excess caloric intake with high-sugar and high-fat diet promote high energy harvesting and lipogenesis. The secretion of adipokines accompanies lipid spillover from fat cells, which contribute to insulin resistance and the expansion of adipose tissue in ectopic sites. Proinflammatory cytokines from adipose tissue macrophages increase the extent of adipose dysfunction.The inflammatory nature of obesity and metabolic syndrome recall the connection between dysbiosis and immune dysfunction. A remarkable association exits between obesity, inflammatory bowel disease, gluten-sensitive enteropathy, and dysbiosis. These conditions compromise the gut mucosa barrier and allow lipopolysaccharide to enter circulation. Unresolved chronic inflammation caused by one condition may overlap or trigger the other(s). Experimental studies and therapeutic trials of fecal microbiota transplantation promise limited improvement in some of these conditions.Typically, metabolic syndrome is considered as a consequence of overnutrition and the vicious cycle of lipogenesis, lipid accumulation, and chronic low-level inflammation. Because of the complex nature of this disorder, it remains inconclusive whether dysbiosis is a cause or consequence of obesity and metabolic syndrome.

Role of gut microbes in acute lung injury/acute respiratory distress syndrome

Acute lung injury (ALI) is an acute, diffuse inflammatory lung condition triggered by factors of severe infections, trauma, shock, burns, ischemia-reperfusion, and mechanical ventilation. It is primarily characterized by refractory hypoxemia and respiratory distress. The more severe form, acute respiratory distress syndrome (ARDS), can progress to multi-organ failure and has a high mortality rate. Despite extensive research, the exact pathogenesis of ALI and ARDS remains complex and not fully understood. Recent advancements in studying the gut microecology of patients have revealed the critical role that gut microbes play in ALI/ARDS onset and progression. While the exact mechanisms are still under investigation, evidence increasingly points to the influence of gut microbes and their metabolites on ALI/ARDS. This review aims to summarize the role of gut microbes and their metabolites in ALI/ARDS caused by various triggers. Moreover, it explores potential mechanisms and discusses how gut microbe-targeting interventions might offer new clinical strategies for the treatment of ALI/ARDS.

Small-molecule TIP60 inhibitors enhance regulatory T cell induction through TIP60-P300 acetylation crosstalk

Foxp3 acetylation is essential to regulatory T (Treg) cell stability and function, but pharmacologically increasing it remains an unmet challenge. Here, we report that small-molecule compounds that inhibit TIP60, an acetyltransferase known to acetylate Foxp3, unexpectedly increase Foxp3 acetylation and Treg induction. Utilizing a dual experimental/computational approach combined with a newly developed FRET-based methodology compatible with flow cytometry to measure Foxp3 acetylation, we unraveled the mechanism of action of these small-molecule compounds in murine and human Treg induction cell cultures. We demonstrate that at low-mid concentrations they activate TIP60 to acetylate P300, a different acetyltransferase, which in turn increases Foxp3 acetylation, thereby enhancing Treg cell induction. These results reveal a potential therapeutic target relevant to autoimmunity and transplant.

Metabolic changes with the occurrence of atherosclerotic plaques and the effects of statins

Atherosclerosis is a common cardiovascular disease caused by the abnormal expression of multiple factors and genes influenced by both environmental and genetic factors. The primary manifestation of atherosclerosis is plaque formation, which occurs when inflammatory cells consume excess lipids, affecting their retention and modification within the arterial intima. This triggers endothelial cell (EC) activation, immune cell infiltration, vascular smooth muscle cell (VSMC) proliferation and migration, foam cell formation, lipid streaks, and fibrous plaque development. These processes can lead to vascular wall sclerosis, lumen stenosis, and thrombosis. Immune cells, ECs, and VSMCs in atherosclerotic plaques undergo significant metabolic changes and inflammatory responses. The interaction of cytokines and chemokines secreted by these cells leads to the onset, progression, and regression of atherosclerosis. The regulation of cell- or cytokine-based immune responses is a novel therapeutic approach for atherosclerosis. Statins are currently the primary pharmacological agents utilised for managing unstable plaques owing to their ability to enhance endothelial function, regulate VSMC proliferation and apoptosis by reducing cholesterol levels, and mitigate the expression and activity of inflammatory cytokines. In this review, we provide an overview of the metabolic changes associated with atherosclerosis, describe the effects of inflammatory responses on atherosclerotic plaques, and discuss the mechanisms through which statins contribute to plaque stabilisation. Additionally, we examine the role of statins in combination with other drugs in the management of atherosclerosis.

Regulatory T cells: A suppressor arm in post-stroke immune homeostasis

The activation of the immune system and the onset of pro- and anti-inflammatory responses play crucial roles in the pathophysiological processes of ischaemic stroke (IS). CD4+ regulatory T (Treg) cells is the main immunosuppressive cell population that is studied in the context of peripheral tolerance, autoimmunity, and the development of chronic inflammatory diseases. In recent years, more studies have focused on immune modulation after IS, and Treg cells have been demonstrated to be essential in the remission of inflammation, nerve regeneration, and behavioural recovery. However, the exact effects of Treg cells in the context of IS remain controversial, with some studies suggesting a negative correlation with stroke outcomes. In this review, we aim to provide a comprehensive overview of the current understanding of Treg cell involvement in post-stroke homeostasis. We summarized the literature focusing on the temporal changes in Treg cell populations after IS, the mechanisms of Treg cell-mediated immunomodulation in the brain, and the potential of Treg cell-based therapies for treatment. The purposes of the current article are to address the importance of Treg cells and inspire more studies to help physicians, as well as scientists, understand the whole map of immune responses during IS.

Midgut microbiota affects the intestinal barrier by producing short-chain fatty acids in Apostichopus japonicus

Introduction

The intestinal microbiota participates in host physiology and pathology through metabolites, in which short-chain fatty acids (SCFAs) are considered principal products and have extensive influence on intestine homeostasis. It has been reported that skin ulceration syndrome (SUS), the disease of Apostichopus japonicus caused by Vibrio splendidus, is associated with the alteration of the intestinal microbiota composition.

Method

To investigate whether the intestinal microbiota affects A. japonicus health via SCFAs, in this study, we focus on the SCFA profiling and intestinal barrier function in A. japonicus treated with V. splendidus.

Results and discussion

We found that V. splendidus could destroy the mid-intestine integrity and downregulate the expression of tight junction proteins ZO-1 and occludin in A. japonicus, which further dramatically decreased microorganism abundance and altered SCFAs contents. Specifically, acetic acid is associated with the largest number of microorganisms and has a significant correlation with occludin and ZO-1 among the seven SCFAs. Furthermore, our findings showed that acetic acid could maintain the intestinal barrier function by increasing the expression of tight junction proteins and rearranging the tight junction structure by regulating F-actin in mid-intestine epithelial cells. Thus, our results provide insights into the effects of the gut microbiome and SCFAs on intestine barrier homeostasis and provide essential knowledge for intervening in SUS by targeting metabolites or the gut microbiota.

Zfp335 establishes eTreg lineage and neonatal immune tolerance by targeting Hadha-mediated fatty acid oxidation

Regulatory T cells (Tregs) are instrumental in maintaining immune tolerance and preventing destructive autoimmunity, but how heterogeneous Treg populations are established remains largely unknown. Here, we show that Zfp335 deletion in Tregs failed to differentiate into effector Tregs (eTregs) and lose Treg-suppressive function and that KO mice exhibited early-onset lethal autoimmune inflammation with unrestricted activation of conventional T cells. Single-cell RNA-Seq analyses revealed that Zfp335-deficient Tregs lacked a eTreg population and showed dramatic accumulation of a dysfunctional Treg subset. Mechanistically, Zfp335-deficient Tregs displayed reduced oxidative phosphorylation and dysfunctional mitochondrial activity. Further studies revealed that Zfp335 controlled eTreg differentiation by regulating fatty acid oxidation (FAO) through direct targeting of the FAO enzyme Hadha. Importantly, we demonstrate a positive correlation between ZNF335 and HADHA expression in human eTregs. Our findings reveal that Zfp335 controls FAO-driven eTreg differentiation to establish immune tolerance.

Metabolic regulation of forkhead box P3 alternative splicing isoforms and their impact on health and disease

Forkhead Box P3 (FOXP3) is crucial for the development and suppressive function of human regulatory T cells (Tregs). There are two predominant FOXP3 splicing isoforms in healthy humans, the full-length isoform and the isoform lacking exon 2, with different functions and regulation mechanisms. FOXP3 splicing isoforms show distinct abilities in the cofactor interaction and the nuclear translocation, resulting in different effects on the differentiation, cytokine secretion, suppressive function, linage stability, and environmental adaptation of Tregs. The balance of FOXP3 splicing isoforms is related to autoimmune diseases, inflammatory diseases, and cancers. In response to environmental challenges, FOXP3 transcription and splicing can be finely regulated by T cell antigen receptor stimulation, glycolysis, fatty acid oxidation, and reactive oxygen species, with various signaling pathways involved. Strategies targeting energy metabolism and FOXP3 splicing isoforms in Tregs may provide potential new approaches for the treatment of autoimmune diseases, inflammatory diseases, and cancers. In this review, we summarize recent discoveries about the FOXP3 splicing isoforms and address the metabolic regulation and specific functions of FOXP3 splicing isoforms in Tregs.

Microbiome-Metabolomic Analysis Reveals Beneficial Effects of Dietary Kelp Resistant Starch on Intestinal Functions of Hybrid Snakeheads (Channa maculata ♀ × Channa argus ♂)

The benefits of resistant starch on hypoglycemia, obesity prevention, antioxidant status and the alleviation of metabolic syndrome have received considerable attention. In this study, we explored how dietary kelp resistant starch (KRS) enhances intestinal morphology and function through a microbiome-metabolomic analysis. Hybrid snakeheads (initial weight: 11.4 ± 0.15 g) were fed experimental diets for 60 days. Fish were fed a basic wheat starch diet and the KRS diet. Dietary KRS improved intestinal morphology and enhanced intestinal antioxidant and digestive capabilities, as evidenced by decreased intestinal damage and upregulated intestinal biochemical markers. The microbiome analysis showed that KRS administration elevated the proportion of butyrate-producing bacteria and the abundance of beneficial bacteria that increases insulin sensitivity. Furthermore, significant alterations in metabolic profiles were observed to mainly associate with the amino acid metabolism (particularly arginine production), the metabolism of cofactors and vitamins, fat metabolism, glutathione metabolism, and the biosynthesis of other secondary metabolites. Additionally, alterations in intestinal microbiota composition were significantly associated with metabolites. Collectively, changes in intestinal microbiota and metabolite profiles produced by the replacement of common starch with dietary KRS appears to play an important role in the development of intestinal metabolism, thus leading to improved intestinal function and homeostasis.

Targeting the metabolism of tumor-infiltrating regulatory T cells

Although targeting the tumor metabolism is performed in cooperation with immunotherapy in the era of precision oncology, ignorance of immune cells' metabolism has resulted in unstable antitumor responses. Tumor-infiltrating regulatory T cells (TI-Tregs) are unique, overcoming the hypoxic, acidic, and nutrient-deficient tumor microenvironments (TMEs) and maintaining immunosuppressive functions. However, secondary autoimmunity caused by systemic Treg depletion remains the 'Sword of Damocles' for current Treg-targeted therapies. In this opinion piece, we propose that metabolically reprogrammed TI-Tregs might represent an obstacle to cancer therapies. Indeed, metabolism-based Treg-targeted therapy might provide higher selectivity for clearing TI-Tregs than traditional kinase/checkpoint inhibitors and chemokine/chemokine receptor blockade; it might also restore the efficacy of targeting the tumor metabolism and eliminate certain metabolic barriers to immunotherapy.

Polysaccharides from Paecilomyces hepiali Prevent Acute Colitis in Association with Modulating Gut Microbiota and Treg/Th17 Immune Balance in Mice

Cordyceps exopolysaccharide (CEP) has shown emerging potential in adjustment of gut microbiota and immune cell function. In this study, a water-soluble CEP with a molecular weight of 58.14 kDa was extracted from the fermentation broth of Paecilomyces hepiali, an endophytic fungus of Cordyceps sinensis. Our results indicated that Paecilomyces hepiali polysaccharide (PHP) showed significantly preventive potential on dextran sulfate sodium (DSS)-induced colitis in mice, which can prevent colon shortening, reduce intestinal epithelial cell (IEC) destruction, suppress inflammatory cell infiltration, and regulate the balance between regulatory T (Treg) cells and T helper type 17 (Th17) cells. Meanwhile, the disturbed gut microbiota was partially restored after PHP treatment. Further Pearson correlation coefficient analyses exhibited that the alteration of the gut microbiota was significantly related to adjustment of the IEC barrier and Treg/Th17 balance. In conclusion, all findings proposed that purified PHP has the potential to develop into a promising agent for colitis prevention and adjuvant therapy via maintaining intestinal homeostasis of gut microbiota and immune system.

Altered intestinal microbiota in children with bronchiolitis

Objective

To investigate the correlation between the alteration of intestinal microbiota and disease in children with bronchiolitis.

Methods

Fifty seven children diagnosed with bronchiolitis from January 2020 to January 2022 in our pediatric department were included as the case group, and another 36 normal children were included as the control group. Stool and blood were collected from both groups for high-throughput sequencing, untargeted metabolite detection and ELISA. A mouse model of RSV infection was established to validate the results of clinical case detection.

Results

Body weight, passive smoking, and a host of other factors were possible as acute bronchiolitis influencing factors in the onset of acute bronchiolitis. The alpha diversity Shannon, Simpson and Pielou's evenness indices were significantly lower in children with acute bronchiolitis than in healthy children with gated levels of Firmicutes, Bacteroidetes and genus levels of Clostridium and other short chain fatty acid-producing bacteria. The relative abundance of short-chain fatty acid (SCFAs)-producing bacteria decreased and the abundance of genus-level sphingolipid-producing bacteria Sphingomonas increased; the progression of acute bronchiolitis is likely to be associated with the abundance of Clostridium and Sphingomonas and higher fecal amino acid concentrations, including FF-MAS, L-aspartic acid, thioinosinic acid, picolinic acid; supplementation with Clostridium butyricum significantly alleviated RSV infection-induced lung inflammation.

Conclusion

The progression of bronchiolitis may be associated with altered intestinal microbiota, decreased SCFAs and elevated sphingolipids metabolism in children. Some fecal bacteria and metabolites may predict the onset of bronchiolitis, and oral administration of Clostridium butyricum may alleviate RSV infection-induced pulmonary inflammation.

Microbiota-assisted iron uptake promotes immune tolerance in the intestine

Iron deficiencies are the most common nonenteric syndromes observed in patients with inflammatory bowel disease, but little is known about their impacts on immune tolerance. Here we show that homeostasis of regulatory T cells in the intestine was dependent on high cellular iron levels, which were fostered by pentanoate, a short-chain fatty acid produced by intestinal microbiota. Iron deficiencies in Treg caused by the depletion of Transferrin receptor 1, a major iron transporter, result in the abrogation of Treg in the intestine and lethal autoimmune disease. Transferrin receptor 1 is required for differentiation of c-Maf+ Treg, major constituents of intestinal Treg. Mechanistically, iron enhances the translation of HIF-2α mRNA, and HIF-2α in turn induces c-Maf expression. Importantly, microbiota-produced pentanoate promotes iron uptake and Treg differentiation in the intestine. This subsequently restores immune tolerance and ameliorated iron deficiencies in mice with colitis. Our results thus reveal an association between nutrient uptake and immune tolerance in the intestine.

Treg-specific deletion of the phosphatase SHP-1 impairs control of inflammation in vivo

Introduction

To achieve a healthy and functional immune system, a delicate balance exists between the activation of conventional T cells (Tcon cells) and the suppression by regulatory T cells (Treg). The tyrosine phosphatase SHP-1, a negative regulator of TCR signaling, shapes this 'activation-suppression' balance by modulating Tcon cell resistance to Treg-mediated suppression. Treg cells also express SHP-1, but its role in influencing Treg function is still not fully understood.

Methods

We generated a Treg-specific SHP-1 deletion model, Foxp3Cre+ Shp-1f/f , to address how SHP-1 affects Treg function and thereby contributes to T cell homeostasis using a combination of ex vivo studies and in vivo models of inflammation and autoimmunity.

Results

We show that SHP-1 modulates Treg suppressive function at different levels. First, at the intracellular signaling level in Treg cells, SHP-1 attenuates TCR-dependent Akt phosphorylation, with loss of SHP-1 driving Treg cells towards a glycolysis pathway. At the functional level, SHP-1 expression limits the in vivo accumulation of CD44hiCD62Llo T cells within the steady state Tcon populations (both CD8+ as well as CD4+ Tcon). Further, SHP-1-deficient Treg cells are less efficient in suppressing inflammation in vivo; mechanistically, this appears to be due to a failure to survive or a defect in migration of SHP-1-deficient Treg cells to peripheral inflammation sites.

Conclusion

Our data identify SHP-1 as an important intracellular mediator for fine-tuning the balance between Treg-mediated suppression and Tcon activation/resistance.

The Bridge Between Ischemic Stroke and Gut Microbes: Short-Chain Fatty Acids

Short-chain fatty acids (SCFAs) are monocarboxylates produced by the gut microbiota (GM) and result from the interaction between diet and GM. An increasing number of studies about the microbiota-gut-brain axis (MGBA) indicated that SCFAs may be a crucial mediator in the MGBA, but their roles have not been fully clarified. In addition, there are few studies directly exploring the role of SCFAs as a potential regulator of microbial targeted interventions in ischemic stroke, especially for clinical studies. This review summarizes the recent studies concerning the relationship between ischemic stroke and GM and outlines the role of SCFAs as a bridge between them. The potential mechanisms by which SCFAs affect ischemic stroke are described. Finally, the beneficial effects of SFCAs-mediated therapeutic measures such as diet, dietary supplements (e.g., probiotics and prebiotics), fecal microbiota transplantation, and drugs on ischemic brain injury are also discussed.

Fatty acid metabolism in adaptive immunity

Fatty acids (FAs) not only are a key component of cellular membrane structure, but also have diverse functions in biological processes. Recent years have seen great advances in understanding of how FA metabolism contributes to adaptive immune response. Here, we review three key processes, FA biosynthesis, FA oxidation and FA uptake, and how they direct T and B cell functions during immune challenges. Then, we will focus on the relationship between microbiota derived FAs, short-chain FAs, and adaptive immunity. Along the way, we will also discuss the outstanding controversies and challenges in the field.

Regulatory immune cells: a review of the novel paradigm of primary Sjogren's syndrome

Primary Sjögren's Syndrome (pSS) is an autoimmune disease that mostly affects women. Patients with pSS experience dry mouth and eyes in addition to signs of systemic disease. pSS was considered a Th1 autoimmune disease for many years. However, in various studies, it has been shown that dysregulation of regulatory cells play critical role in the pathogenesis of the disease. This review focuses on studies supporting this view and answers questions about the role of regulatory cells in the pathogenesis of pSS.

Effects of intestinal microbes on rheumatic diseases: A bibliometric analysis

Background

Rheumatic diseases (RD) are a group of multi-system inflammatory autoimmune diseases whose causes are still under study. In the past few decades, researchers have found traces of the association between rheumatic diseases and intestinal microbiota, which can partially explain the pathogenesis of rheumatic diseases. We aimed to describe the research trend and main divisions on how gut flora interreacts with rheumatic diseases, and discussed about the possible clinical applications.

Methods

We analyzed bibliometric data from the Web of Science core collection (dated 15th May 2022). Biblioshiny R language software packages (bibliometrix) were used to obtain the annual publication and citations, core sources according to Bradford's law, and country collaboration map. We designed and verified the keyword co-occurrence network and strategic diagram with the help of VOSviewer and CiteSpace, subdivided the research topic into several themes and identified research dimensions. The tables of most local cited documents and core sources were processed manually. Furthermore, the Altmetric Attention Score and the annual Altmetric Top 100 were applied to analyze the annual publication and citation.

Results

From a total of 541 documents, we found that the overall trend of annual publication and citation is increasing. The major research method is to compare the intestinal microbial composition of patients with certain rheumatic disease and that of the control group to determine microbial alterations related to the disease's occurrence and development. According to Bradford's law, the core sources are Arthritis and Rheumatology, Annals of the Rheumatic Diseases, Current Opinion in Rheumatology, Nutrients, Rheumatology, and Journal of Rheumatology. Since 1976, 101 countries or regions have participated in studies of rheumatology and intestinal microbes. The United States ranks at the top and has the broadest academic association with other countries. Five themes were identified, including the pivotal role of inflammation caused by intestinal bacteria in the rheumatic pathogenesis, the close relationship between rheumatic diseases and inflammatory bowel disease, immunoregulation mechanism as a mediator of the interaction between rheumatic diseases and gut flora, dysbiosis and decreased diversity in intestine of patients with rheumatic diseases, and the influence of oral flora on rheumatic diseases. Additionally, four research dimensions were identified, including pathology, treatment, disease, and experiments.

Conclusion

Studies on rheumatic diseases and the intestinal microbiota are growing. Attention should be paid to the mechanism of their interaction, such as the microbe-immune-RD crosstalk. Hopefully, the research achievements can be applied to diseases' prevention, diagnosis, and treatment, and our work can contribute to the readers' future research.

Macrophage-derived exosome promotes regulatory T cell differentiation in malignant pleural effusion

Introduction

Tumor-associated macrophages are one of the key components of the tumor microenvironment. The immunomodulatory activity and function of macrophages in malignant pleural effusion (MPE), a special tumor metastasis microenvironment, have not been clearly defined.

Methods

MPE-based single-cell RNA sequencing data was used to characterize macrophages. Subsequently, the regulatory effect of macrophages and their secreted exosomes on T cells was verified by experiments. Next, miRNA microarray was used to analyze differentially expressed miRNAs in MPE and benign pleural effusion, and data from The Cancer Genome Atlas (TCGA) was used to evaluate the correlation between miRNAs and patient survival.

Results

Single-cell RNA sequencing data showed macrophages were mainly M2 polarized in MPE and had higher exosome secretion function compared with those in blood. We found that exosomes released from macrophages could promote the differentiation of naïve T cells into Treg cells in MPE. We detected differential expression miRNAs in macrophage-derived exosomes between MPE and benign pleural effusion by miRNA microarray and found that miR-4443 was significantly overexpressed in MPE exosomes. Gene functional enrichment analysis showed that the target genes of miR-4443 were involved in the regulation of protein kinase B signaling and lipid biosynthetic process.

Conclusions

Taken together, these results reveal that exosomes mediate the intercellular communication between macrophages and T cells, yielding an immunosuppressive environment for MPE. miR-4443 expressed by macrophages, but not total miR-4443, might serve as a prognostic marker in patients with metastatic lung cancer.

The role of metabolism on regulatory T cell development and its impact in tumor and transplantation immunity

Regulatory CD4⁺ T (Treg) cells play a key role in the induction of immune tolerance and in the prevention of autoimmune diseases. Treg cells are defined by the expression of transcription factor FOXP3, which ensures proliferation and induction of the suppressor activity of this cell population. In a tumor microenvironment, after transplantation or during autoimmune diseases, Treg cells can respond to various signals from their environment and this property ensures their suppressor function. Recent studies showed that a metabolic signaling pathway of Treg cells are essential in the control of Treg cell proliferation processes. This review presents the latest research highlights on how the influence of extracellular factors (e.g. nutrients, vitamins and metabolites) as well as intracellular metabolic signaling pathways regulate tissue specificity of Treg cells and heterogeneity of this cell population. Understanding the metabolic regulation of Treg cells should provide new insights into immune homeostasis and disorders along with important therapeutic implications for autoimmune diseases, cancer and other immune-system-mediated disorders.

Immunometabolic alterations in lupus: where do they come from and where do we go from there?

Systemic lupus erythematosus (SLE) is an autoimmune disease in which the overactivation of the immune system has been associated with metabolic alterations. Targeting the altered immunometabolism has been proposed to treat SLE patients based on their results obtained and mouse models of the disease. Here, we review the recent literature to discuss the possible origins of the alterations in the metabolism of immune cells in lupus, the dominant role of mitochondrial defects, technological advances that may move the field forward, as well as how targeting lupus immunometabolism may have therapeutic potential.

Intestinal microbiota metabolizing Houttuynia cordata polysaccharides in H1N1 induced pneumonia mice contributed to Th17/Treg rebalance in gut-lung axis

Influenza A virus is intricately linked to dysregulation of gut microbiota and host immunity. Previous study revealed that Houttuynia cordata polysaccharides (HCP) exert the therapeutic effect on influenza A virus inducing lung and intestine damage via regulating pulmonary and intestinal mucosal immunity. However, whether this result was due to the regulation of gut microbiota in the gut-lung axis remains unclear. Here, we firstly found that the elimination of gut microbiota using antibiotic cocktails led to both loss of the protective effect of HCP on intestine and lung injury, and reduction of the efficacy on regulating Th17/Treg balance in gut-lung axis. Fecal microbiota transplantation study confirmed that the gut microbiota fermented with HCP under pathological conditions (H1N1 infection) was responsible for reducing pulmonary and intestinal injury. Moreover, the interaction of HCP and gut microbiota under pathological conditions exhibited not only much more abundant gut microbial diversity, but also higher content of the acetate. Our results demonstrated that the underlying mechanism to ameliorate viral pneumonia in mice involving Th17/Treg rebalance via the gut microbiota and HCP metabolite (acetate) metabolized in pneumonia mice. Our results provided a new insight for macromolecular polysaccharides through targeting intestinal microenvironment reducing distant pulmonary infection.

Fine-tuning of regulatory T cells is indispensable for the metabolic steatosis-related hepatocellular carcinoma: A review

The majority of chronic hepatic diseases are caused by nutritional imbalance. These nutritional inequities include excessive intake of alcohol and fat, which causes alcoholic liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD), respectively. The pathogenesis of hepatic diseases is mainly dependent on oxidative stress, autophagy, DNA damage, and gut microbiota and their metabolites. These factors influence the normal physiology of the liver and impact the hepatic microenvironment. The hepatic microenvironment contains several immune cells and inflammatory cytokines which interact with each other and contribute to the progression of chronic hepatic diseases. Among these immune cells, Foxp3⁺ CD4⁺ regulatory T cells (Tregs) are the crucial subset of CD4⁺ T cells that create an immunosuppressive environment. This review emphasizes the function of Tregs in the pathogenesis of ALD and NAFLD and their role in the progression of NAFLD-associated hepatocellular carcinoma (HCC). Briefly, Tregs establish an immunosuppressive landscape in the liver by interacting with the innate immune cells and gut microbiota and their metabolites. Meanwhile, with the advancement of steatosis, these Tregs inhibit the proliferation, activation and functions of other cytotoxic T cells and support the progression of simple steatosis to HCC. Briefly, it can be suggested that targeting Tregs can act as a favourable prognostic indicator by modulating steatosis and insulin resistance during the pathogenesis of hepatic steatosis and NAFLD-associated HCC.

Lipid metabolism in tumor microenvironment: novel therapeutic targets

Bioactive lipid molecules have been proposed to play important roles linking obesity/metabolic syndrome and cancers. Studies reveal that aberrant lipid metabolic signaling can reprogram cancer cells and non-cancer cells in the tumor microenvironment, contributing to cancer initiation, progression, metastasis, recurrence, and poor therapeutic response. Existing evidence indicates that controlling lipid metabolism can be a potential strategy for cancer prevention and therapy. By reviewing the current literature on the lipid metabolism in various cancers, we summarized major lipid molecules including fatty acids and cholesterol as well as lipid droplets and discussed their critical roles in cancer cells and non-cancer in terms of either promoting- or anti-tumorigenesis. This review provides an overview of the lipid molecules in cellular entities and their tumor microenvironment, adding to the existing knowledge with lipid metabolic reprogramming in immune cells and cancer associated cells. Comprehensive understanding of the regulatory role of lipid metabolism in cellular entities and their tumor microenvironment will provide a new direction for further studies, in a shift away from conventional cancer research. Exploring the lipid-related signaling targets that drive or block cancer development may lead to development of novel anti-cancer strategies distinct from traditional approaches for cancer prevention and treatment.

Therapeutic opportunities to modulate immune tolerance through the metabolism-chromatin axis

The ability of the immune system to discriminate external stimuli from self-components - namely immune tolerance - occurs through a coordinated cascade of events involving a dense network of immune cells. Among them, CD4⁺CD25⁺ T regulatory cells are crucial to balance immune homeostasis and function. Growing evidence supports the notion that energy metabolites can dictate T cell fate and function via epigenetic modifications, which affect gene expression without altering the DNA sequence. Moreover, changes in cellular metabolism couple with activation of immune pathways and epigenetic remodeling to finely tune the balance between T cell activation and tolerance. This Review summarizes these aspects and critically evaluates novel possibilities for developing therapeutic strategies to modulate immune tolerance through metabolism via epigenetic drugs.

Gut microbiome-produced metabolites in pigs: a review on their biological functions and the influence of probiotics

The gastrointestinal tract is a complex ecosystem that contains a large number of microorganisms with different metabolic capacities. Modulation of the gut microbiome can improve the growth and promote health in pigs. Crosstalk between the host, diet, and the gut microbiome can influence the health of the host, potentially through the production of several metabolites with various functions. Short-chain and branched-chain fatty acids, secondary bile acids, polyamines, indoles, and phenolic compounds are metabolites produced by the gut microbiome. The gut microbiome can also produce neurotransmitters (such as γ-aminobutyric acid, catecholamines, and serotonin), their precursors, and vitamins. Several studies in pigs have demonstrated the importance of the gut microbiome and its metabolites in improving growth performance and feed efficiency, alleviating stress, and providing protection from pathogens. The use of probiotics is one of the strategies employed to target the gut microbiome of pigs. Promising results have been published on the use of probiotics in optimizing pig production. This review focuses on the role of gut microbiome-derived metabolites in the performance of pigs and the effects of probiotics on altering the levels of these metabolites.

The Pathological Mechanism Between the Intestine and Brain in the Early Stage of Parkinson's Disease

Parkinson's disease (PD) is the second most common chronic progressive neurodegenerative disease. The main pathological features are progressive degeneration of neurons and abnormal accumulation of α-synuclein. At present, the pathogenesis of PD is not completely clear, and many changes in the intestinal tract may be the early pathogenic factors of PD. These changes affect the central nervous system (CNS) through both nervous and humoral pathways. α-Synuclein deposited in the intestinal nerve migrates upward along the vagus nerve to the brain. Inflammation and immune regulation mediated by intestinal immune cells may be involved, affecting the CNS through local blood circulation. In addition, microorganisms and their metabolites may also affect the progression of PD. Therefore, paying attention to the multiple changes in the intestinal tract may provide new insight for the early diagnosis and treatment of PD.

Treatment with Distinct Antibiotic Classes Causes Different Pulmonary Outcomes on Allergic Airway Inflammation Associated with Modulation of Symbiotic Microbiota

Background

Asthma is a chronic pulmonary disease that affects about 300 million people worldwide. Previous studies have associated antimicrobial use with allergies, but the real impact of antibiotics on asthma is still elusive. We investigated the potential impact of amoxicillin (Amox), trimethoprim/sulfamethoxazole (TMP/SMX), and metronidazole (Metro) in a murine model of OVA-induced allergic airway inflammation.

Methods

BALB/c mice received three cycles of 7 days of antibiotics in drinking water followed by 7 days washout and were sensitized i.p. with OVA/Alum at days 0 and 14. After the end of the last antibiotic washout, the mice were challenged with aerosolized OVA. Pulmonary parameters were evaluated, and serum, BAL, and feces were collected for analysis.

Results

Amox- and TMP/SMX-treated animals displayed more severe allergic airway inflammation parameters with increased airway hyperresponsiveness, reduced lung alveolar volume, and increased levels in BAL of IL-4 and IL-6. In contrast, Metro-treated mice showed preserved FEV-50, decreased lung inflammation, and higher levels of butyrate and propionate in their feces. Metro treatment was associated with increased OVA-specific IgA in serum. BAL microbiota was abundant in allergic groups but not in nonallergic controls with the Amox-treated group displaying the increased frequency of Proteobacteria, while Metro and TMP/SMX showed increased levels of Firmicutes. In the gut, we observed the enrichment of Akkermansia muciniphila associated with reduced airway inflammation phenotype in the Metro group, even after the recovery period.

Conclusion

Our data suggest that different antibiotic treatments may impact the course of experimental allergic airway inflammation in diverse ways by several mechanisms, including modulation of short-chain fat acids production by intestinal microbiota.