Gut microbiota and rheumatoid arthritis: From pathogenesis to novel therapeutic opportunities

A 10-year knowledge mapping of T cells in rheumatoid arthritis: A bibliometric analysis

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease of autoimmune origin. T cells play crucial roles in the initiation and progression of RA. Although bibliometric methods have been widely used to synthesize knowledge trajectories across different biomedical fields, it has hardly been used to underscore the knowledge trends in relation to T cell and RA. This study used bibliometric methods to delineate the evolution of research on T cells and RA. Data were sourced from the Web of Science™ Core Collection and were scientometrically analyzed using CiteSpace and VOSviewer. From 2014 to 2023, 7037 papers on T cells and RA were retrieved. The number of annual publications is stable between 600 and 800, and the citation frequency continues to rise. The United States, China, the United Kingdom and Japan were the most productive countries. Karolinska Institute, and Harvard Medical School were the institutions that published the most research papers. Wei W, Cho ML, and Park SH were the most prolific authors. Mclnnes IB and Smolen JS were the most frequently cited authors. The journals with the most articles are Frontiers in Immunology, Arthritis Research & Therapy, and Arthritis & Rheumatology. Current research hotspots include pathogenic factors and targeted biological therapy, immune mechanisms, inflammatory mechanisms, and bone destruction mechanisms. The current research frontiers in this field are gut microbiota, identification, fibroblast-like synoviocytes, biologic therapy, mesenchymal stem cells, and risk. This work provides new insights into the scientific research and clinical application of T cells to develop therapeutic targets for RA.

The Role of Diet in Modulating Inflammation and Oxidative Stress in Rheumatoid Arthritis, Ankylosing Spondylitis, and Psoriatic Arthritis

Rheumatic diseases such as rheumatoid arthritis (RA), ankylosing spondylitis (AS), and psoriatic arthritis (PsA) are chronic autoimmune disorders characterized by persistent inflammation and oxidative stress, leading to joint damage and reduced quality of life. In recent years, increasing attention has been given to diet as a modifiable environmental factor that can complement pharmacological therapy. This review summarizes current evidence on how key dietary components-such as omega-3 fatty acids, fiber, polyphenols, and antioxidant vitamins-affect inflammatory pathways and oxidative balance. Special emphasis is placed on the Mediterranean diet, low-starch diets, and hypocaloric regimens, which have shown potential in improving disease activity. The gut microbiota emerges as a critical mediator between diet and immune function, with dietary interventions capable of restoring eubiosis and strengthening the intestinal barrier. Additionally, this paper discusses challenges in the clinical implementation of diet therapy, the need for personalized nutritional strategies, and the importance of integrating diet into holistic patient care. Collectively, findings suggest that dietary interventions may reduce disease activity, mitigate systemic inflammation, and enhance patients' overall well-being.

Impact of Gut Microbiota and Probiotics on Rheumatoid Arthritis: A Potential Treatment Challenge

Over the past few decades, there has been a surge in global study on the relationship between gut microbiota and human health. Numerous human illnesses have been linked to dysbiosis. Gram-positive firmicutes and Gram-negative bacteroidetes are the two leading bacterial phyla that make up 90% of the gut microbiome. Many symbionts in the gut environment establish intricate relationships with host defense to stop both local and non-native dangerous bacteria from colonizing and invading. Dysbiosis alters the paracellular route and damages the epithelium, enabling them to penetrate the epithelium and come into contact with the immune cells. Impaired intestinal barrier function, immune regulation mediated by metabolites derived from the gut microbiota, posttranslational modification of host proteins such as increased citrullination, regulation of the gut microbiota's effect on immune cells, intestinal epithelial cell autophagy, interaction between the microbiome and human leukocyte antigen alleles, and interaction with microRNAs are some of the mechanisms involved in rheumatoid arthritis (RA). The gut microbiota, Prevotella copri, and Collinsella spp. were shown to be higher in the early/preclinical phases of RA, while Bacteroidetes, Bifidobacteria, and Eubacterium rectale were found to be lower. Probiotic-based early dietary intervention may reduce inflammation and slow the rate of joint deterioration, and such intervention can also aid in the restoration of gut microbiota equilibrium. This review article describes the gut microbial dysbiosis and role of probiotics in RA.

Dual regulatory effects of gut microbiota and their metabolites in rheumatoid arthritis: balancing pathogenic and protective mechanisms

Rheumatoid arthritis is a chronic autoimmune disorder characterized by destructive, symmetric joint inflammation and synovitis, resulting in substantial disability that profoundly compromises patients' quality of life. Its pathogenesis encompasses complex interactions between genetic and environmental factors. Recent advances in bacterial DNA sequencing technologies have uncovered a significant correlation between the human gut microbiota composition and rheumatoid arthritis progression. Growing clinical and experimental evidence establishes the gut-joint axis as a crucial mediator in rheumatoid arthritis pathogenesis. Comprehensive investigation of gut microbial communities and their metabolites' influence on rheumatoid arthritis mechanisms, coupled with the elucidation of microbiome's bidirectional regulatory effects in disease development, not only deepens our understanding of pathological processes but also establishes a theoretical framework for developing novel diagnostic biomarkers and personalized therapeutic interventions to enhance patient outcomes.

Escherichia coli aggravates inflammatory response in mice oral mucositis through regulating Th17/Treg imbalance

Introduction

Microbial dysbiosis links to mucosal immune dysregulation, but the specific bacterial contributions to oral mucosal inflammation remain unclear. Escherichia coli (E. coli), a pathogen well-characterized in mucosal immunity and immune regulation studies, has been observed to be enriched in chronic oral inflammatory lesions and was reported to modulate T helper 17 cells (Th17)/T regulatory cells (Treg) homeostasis. Here, we developed an oral mucositis mouse model via tongue scratch and E. coli topical application to investigate its role in Th17/Treg imbalance.

Methods

The inflammatory infiltration was evaluated by macroscopic photography and HE staining. The expression of inflammatory factors in tongue tissue and peripheral blood of mice were detected by immunohistochemical staining and enzyme-linked immunosorbent assay. The number of Th17 and Treg in mice spleen lymphocytes were evaluated with flow cytometry. Differential gene expression analysis, functional enrichment analysis and immune infiltration analysis were performed using RNA-seq data from oral lichen planus (OLP).

Results

E. coli stimulation aggravated inflammatory responses induced by scratching in lingual mucosa of mice, including increased local and systemic expression of interleukin 6 (IL6), interleukin 17 (IL17), chemokine receptor 6 (CCR6) and chemokine C-C motif ligand 20 (CCL20), increased proportions of Th17 cells and increased Th17/Treg ratio in spleen lymphocytes. Analysis of RNA-seq data from OLP revealed alterations in antimicrobial responses and inflammatory factors associated with upregulation of Th17/Treg balance.

Conclusion

This study supports the role of E. coli in promoting oral mucosal inflammation and provides an experimental basis for in vivo study of OLP from the perspective of microorganisms.

The influence of the gut microbiota on B cells in autoimmune diseases

Mounting evidence shows that gut microbiota communities and the human immune system coexist and influence each other, and there are a number of reports of a correlation between specific changes in gut microbiota and the occurrence of autoimmune diseases. B lymphocytes play a central role in the regulation of both gut microbiota communities and in autoimmune diseases. Here, we summarize evidence of the influence of gut microbiota-B cell pathways on autoimmune diseases and how B cells regulate microorganisms, which provides mechanistic insights with relevance for identification of potential therapeutic targets and related fields.

Current Approaches and Implications in Discovery of Novel Bioactive Products from Microbial Sources

Bioactive Natural Products (BNPs) are in high demand due to their disease-preventive capabilities and resistance to pathogens. However, our understanding of BNP-producing microbes is limited, because many microbial populations remain uncultivated. Various approaches have been employed to explore the potential of these hidden microbes for new bioactive therapeutic compounds. Nevertheless, the possibility of discovering BNPs from microbial communities is largely cryptic due to their unculturable nature and the absence of triggers to activate the dormant Biosynthetic Gene Clusters (BGCs). Metagenome sequencing, followed by mining and characterization, is an effective approach for discovering new therapeutic BNPs. The inactive state of BGCs can be activated through the combinatorial interaction of different microbial communities within a common niche, overcoming programmable co-evolutionary stress and producing new BNPs. The present review discusses and explores the potential of hidden, uncultivated microbes for discovering novel Bioactive Natural Products (BNPs). Moreover, it provides insights into optimizing microbial production systems and fostering sustainable drug discovery and development practices by integrating multidisciplinary strategies. This review also emphasizes the critical role of microbial sources in the ongoing search for new bioactive products that can meet the demands of modern healthcare and environmental sustainability.

High-throughput metabolomics exploring the pharmacological effects and mechanism of icariin on rheumatoid arthritis rat based on ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

Introduction

Metabolomics could provide insights into the pharmacological effects and action mechanisms of drugs through assessment of the changes in relevant biomarkers and biological pathways. Icariin (ICA) is a promising ffavonoid compound known to have significant anticancer activity; however, the pharmacological mechanisms of ICA in the treatment of rheumatoid arthritis (RA) need to be explored further.

Methods

The changes in the metabolic profiles of serum samples were revealed using non-targeted metabolomics based on ultrahigh-performance liquid chromatography coupled with quadrupole time-of-fight mass spectrometry. Tissue histopathology, physical parameters, and biochemical indicators were also measured and analyzed to reveal the mechanisms of ICA in the treatment of RA.

Results and discussion

Thirty-one potential biomarkers were identified to highlight the metabolic disorders in an RA animal model, out of which twenty-three were regulated by ICA treatment. These biomarkers were mainly involved in alanine, aspartate, and glutamate metabolism; arachidonic acid metabolism; citrate cycle; pyruvate metabolism; and glycolysis/gluconeogenesis pathways. The anticancer mechanism of ICA on RA may be attributed to amelioration of the amino acid metabolism, unsaturated fatty acid metabolism, citrate cycle, pyruvate metabolism, and others, which in turn regulate the oxidative stress state and inflammatory effects. Thus, metabolomics is a promising approach for revealing the biomarker distribution and pathways of RA to determine the effects and mechanisms of ICA, which can benefit the development of natural medicines.

A microbiota pattern associated with cardiovascular events in secondary prevention: the CORDIOPREV study

BACKGROUND AND AIMS

Preventing new cardiovascular events in patients with established cardiovascular disease (CVD) is a daunting task for clinicians. Intestinal microbiota may help identify patients at risk, thus improving the strategies of secondary prevention. The aim of this study was to evaluate the baseline differences between the gut microbiota from coronary heart disease (CHD) patients suffering new major adverse cardiovascular events (MACEs) in the following 7 years, compared with CHD patients who did not undergo new MACE in this period, and to build a score associated with the risk of suffering new MACE.

METHODS

Within the framework of the CORDIOPREV study, a clinical trial that involved 1002 patients with CHD, intestinal microbiota was examined in patients with available faecal samples (n = 679, 132 MACE), through 16S metagenomics on the Illumina MiSeq and Quiime2 software. Lipopolysaccharide (LPS) was measured using limulus amoebocyte lysate test.

RESULTS

Random survival forest identified 10 bacterial taxa with a higher predictive power for MACE incidence. Receiver operating characteristic curves yielded an area under the curve of 65.2% (59.1%-71.3%) in the training set and 68.6% (59.3%-77.9%) in the validation set. The intestinal microbiota risk score was associated with a MACE incidence hazard ratio of 2.01 (95% confidence interval 1.37-3.22). Lipopolysaccharide analysis showed a greater LPS post-prandial fold change in the MACE group (P = .005).

CONCLUSIONS

These results reinforce the relationship between intestinal microbiota and CVD and suggest that a microbiota profile is associated with MACE in CHD patients, in addition to higher endotoxaemia.

The Oral-Gut Microbiome-Brain Axis in Cognition

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline and neuronal loss, affecting millions worldwide. Emerging evidence highlights the oral microbiome-a complex ecosystem of bacteria, fungi, viruses, and protozoa as a significant factor in cognitive health. Dysbiosis of the oral microbiome contributes to systemic inflammation, disrupts the blood-brain barrier, and promotes neuroinflammation, processes increasingly implicated in the pathogenesis of AD. This review examines the mechanisms linking oral microbiome dysbiosis to cognitive decline through the oral-brain and oral-gut-brain axis. These interconnected pathways enable bidirectional communication between the oral cavity, gut, and brain via neural, immune, and endocrine signaling. Oral pathogens, such as Porphyromonas gingivalis, along with virulence factors, including lipopolysaccharides (LPS) and gingipains, contribute to neuroinflammation, while metabolic byproducts, such as short-chain fatty acids (SCFAs) and peptidoglycans, further exacerbate systemic immune activation. Additionally, this review explores the influence of external factors, including diet, pH balance, medication use, smoking, alcohol consumption, and oral hygiene, on oral microbial diversity and stability, highlighting their role in shaping cognitive outcomes. The dynamic interplay between the oral and gut microbiomes reinforces the importance of microbial homeostasis in preserving systemic and neurological health. The interventions, including probiotics, prebiotics, and dietary modifications, offer promising strategies to support cognitive function and reduce the risk of neurodegenerative diseases, such as AD, by maintaining a diverse microbiome. Future longitudinal research is needed to identify the long-term impact of oral microbiome dysbiosis on cognition.

Probiotic Interventions in Systemic Sclerosis Patients: A Systematic Review and Future Prospects

Background and Aims

Systemic sclerosis (SSc) is an uncommon autoimmune connective tissue disease distinguished by fibrosis and vascular abnormalities, often leading to gastrointestinal problems. This review explores the potential of probiotics in managing SSc-related gastrointestinal issues and modulating immune responses, highlighting the need for innovative treatments to improve patient well-being.

Methods

We performed an extensive literature search up to October 2023 in databases, including Web of Science, PubMed/MEDLINE, and Scopus.

Result

This review detected four articles that investigated the impact of probiotics on SSc. These studies, comprising non-randomized observational studies and randomized clinical trials, provide preliminary insights suggesting that probiotics may be efficacious in modulating the immune response and, consequently, in improving gastrointestinal symptoms in SSc patients.

Conclusion

The comprehensive review suggests that probiotics may aid in managing gastrointestinal symptoms and modulating immune responses in SSc. However, it is essential to acknowledge the limited existing evidence, underscoring the need for more rigorous randomized controlled trials to thoroughly assess their effectiveness.

Gut microbiota regulates gut homeostasis, mucosal immunity and influences immune-related diseases

The intestinal microbiome constitutes a sophisticated and massive ecosystem pivotal for maintaining gastrointestinal equilibrium and mucosal immunity via diverse pathways. The gut microbiota is continuously reshaped by multiple environmental factors, thereby influencing overall wellbeing or predisposing individuals to disease state. Many observations reveal an altered microbiome composition in individuals with autoimmune conditions, coupled with shifts in metabolic profiles, which has spurred ongoing development of therapeutic interventions targeting the microbiome. This review delineates the microbial consortia of the intestine, their role in sustaining gastrointestinal stability, the association between the microbiome and immune-mediated pathologies, and therapeutic modalities focused on microbiome modulation. We emphasize the entire role of the intestinal microbiome in human health and recommend microbiome modulation as a viable strategy for disease prophylaxis and management. However, the application of gut microbiota modification for the treatment of immune-related diseases, such as fecal microbiota transplantation and probiotics, remain quite challenging. Therefore, more research is needed into the role and mechanisms of these therapeutics.

Oxidative Stress, Gut Microbiota, and Extracellular Vesicles: Interconnected Pathways and Therapeutic Potentials

Oxidative stress (OS) and gut microbiota are crucial factors influencing human health, each playing a significant role in the development and progression of chronic diseases. This review provides a comprehensive analysis of the complex interplay between these two factors, focusing on how an imbalance between reactive oxygen species (ROS) and antioxidants leads to OS, disrupting cellular homeostasis and contributing to a range of conditions, including metabolic disorders, cardiovascular diseases, neurological diseases, and cancer. The gut microbiota, a diverse community of microorganisms residing in the gastrointestinal tract, is essential for regulating immune responses, metabolic pathways, and overall health. Dysbiosis, an imbalance in the gut microbiota composition, is closely associated with chronic inflammation, metabolic dysfunction, and various diseases. This review highlights how the gut microbiota influences and is influenced by OS, complicating the pathophysiology of many conditions. Furthermore, emerging evidence has identified extracellular vesicles (EVs) as critical facilitators of cellular crosstalk between the OS and gut microbiota. EVs also play a crucial role in signaling between the gut microbiota and host tissues, modulating immune responses, inflammation, and metabolic processes. The signaling function of EVs holds promise for the development of targeted therapies aimed at restoring microbial balance and mitigating OS. Personalized therapeutic approaches, including probiotics, antioxidants, and fecal microbiota transplantation-based strategies, can be used to address OS-related diseases and improve health outcomes. Nonetheless, further research is needed to study the molecular mechanisms underlying these interactions and the potential of innovative interventions to offer novel strategies for managing OS-related diseases and enhancing overall human health.

Gut microbiota and their metabolites in the immune response of rheumatoid arthritis: Therapeutic potential and future directions

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by persistent joint inflammation, damage, and loss of function. In recent years, the role of gut microbiota and its metabolites in immune regulation has attracted increasing attention. The gut microbiota influences the host immune system's homeostasis through various mechanisms, regulating the differentiation, function, and immune tolerance of immune cells. Dysbiosis of the gut microbiota in RA patients is closely associated with abnormal activation of immune cells and excessive secretion of inflammatory cytokines. Metabolites produced by the gut microbiota, such as short-chain fatty acids (SCFAs), tryptophan metabolites, bile acids, and amino acid metabolites, play a critical role in immune responses, regulating the functions of immune cells like T cells, B cells, and macrophages, and inhibiting the release of pro-inflammatory cytokines. Restoring the balance of the gut microbiota and optimizing the production of metabolic products may become a new strategy for RA treatment. This review discusses the role of gut microbiota and its metabolites in the immune response of RA, exploring how they influence the immunopathological process of RA through the regulation of immune cells and key immune factors. It also provides a theoretical basis for future therapeutic strategies based on gut microbiota modulation.

Disruption of Gut Microbiota and Associated Fecal Metabolites in Collagen-Induced Arthritis Mice During the Early Stage

Background

Rheumatoid arthritis (RA) is a chronic autoimmune disease and increasing evidence suggests that disturbances in the composition and function of gut microbiota are potentially implicated in the progression of RA. Further revealing the microbiota and related metabolic disorders in the preclinical stage of RA (pre-RA) is of great significance for exploration of disease mechanisms.

Methods

DBA/1 mice were injected with type II collagen on days 0 and 21 to establish collagen-induced arthritis (CIA) mouse model. Footpad thickness, serum autoantibodies, and joint histopathology were used to assess the progression of RA. A combination of 16S rRNA sequencing, untargeted metabolomics and targeted short-chain fatty acids (SCFAs) analysis were employed to comprehensively investigate the alterations of gut microbiota and fecal metabolites in CIA during the pre-RA stage.

Results

20 days after the initial collagen immunization, CIA mice showed immune responses without joint symptoms, alongside gut microbiota disruption. Alterations were observed in 20 microbial taxa, including Oscillospira, Bifidobacterium, Ruminococcus, Allobaculum, Alistipes, Lactobacillus, and Candidatus_Arthromitus, etc. Untargeted and targeted metabolomics identified 33 altered fecal metabolites, mainly including sugars and their derivatives, amino acids, long-chain fatty acids and SCFAs, etc. Correlation analysis showed significant correlations between specific gut microbial abundances and fecal metabolite levels. Especially, SCFAs were strongly associated with Bifidobacterium, Alistipes, Ruminococcus, Anaerotruncus, and Allobaculum.

Conclusion

These findings suggest that collagen immunization leads to disruption of gut microbiome and induces changes of fecal metabolites in mice, which may play a key role in early development of RA in CIA mice.

Specific Composition Diets and Improvement of Symptoms of Immune-Mediated Inflammatory Diseases in Adulthood-Could the Comparison Between Diets Be Improved?

Diet is considered a possible cofactor, which affects the immune system and potentially causes dysregulation of intestinal homeostasis and inflammation. This study aimed to review the quality of evidence on the effects of specific diet composition on symptoms of immune-mediated inflammatory diseases (IMIDs), including rheumatoid arthritis (RA), spondyloarthritis, multiple sclerosis (MS), inflammatory bowel disease (IBD) [remission maintenance of Crohn's disease and ulcerative colitis], psoriasis and psoriatic arthritis in adult patients. We conducted a review of meta-analyses and Cochrane systematic reviews using PubMed and EMBASE, from inception to September 2024, and Google Scholar. The methodological quality of the meta-analyses was assessed using the AMSTAR 2 rating system. Three Cochrane systematic reviews and eight meta-analyses were evaluated. Some specific composition diets have been shown to reduce the symptoms of RA, IBD, and MS and improve activity parameters in IBD and RA, with critically low or low levels of evidence. The reduction in inflammatory biomarker levels is unclear. This review summarizes the global evidence for specific dietary interventions, mostly with anti-inflammatory properties due to their components, to improve IMID symptoms, clarifying the weaknesses of clinical trials and dietary meta-analyses with critically low or low levels of evidence; and shows the need to use indices such as the Dietary Inflammatory Index, which allows diets to be classified by their pro-inflammatory or anti-inflammatory food content, to better compare diet groups in clinical trials. The difficulty of obtaining high-level evidence from dietary studies is apparent and may delay the application of the results. Clinicians should be aware of the role of diets with anti-inflammatory properties as a complement to pharmacological treatments in IMIDs.

Bifidobacterium animalis BD400 protects from collagen-induced arthritis through histidine metabolism

Background

Rheumatoid arthritis (RA) is a common chronic and systemic autoimmune disease. Numerous clinical studies have indicated a correlation between alterations in gut microbiota and the onset and progression of RA. This research aims to restore intestinal microbiota to a healthy state through the oral administration of Bifidobacterium in the early stages with the goal of delaying the onset and progression of RA.

Methods

Collagen-induced arthritis (CIA) rat model was constructed to assess the development of RA using arthritis clinical scores, paw thickness, pathological analysis of knee joint. The immune response was evaluated by determinating specific antibodies and cytokines in serum and synovial fluid. The expression of intestinal barrier protein was analyzed by qPCR to evaluate the intestinal barrier function. Alterations in gut microbiota and metabolites were assessed by 16S rDNA and non-targeted metabolomics.

Results

The findings reveal that administering Bifidobacterium animalis BD400 orally led to a significant reduction in arthritis clinical scores and paw swelling thickness in CIA rats. Additionally, there was a decrease in osteo-facial fusion and calcified cartilage thickening in the knee joint. Furthermore, the oral administration of B. animalis BD400 resulted in the down-regulation of inflammatory factors TNF-α and collagenase MMP-13 in the knee joint. Levels of specific antibodies (anti-CII IgG, anti-CII IgG1, and anti-CII IgG2a) and cytokine IL-17A in serum, as well as cytokines (TNF-α and IL-1β) in the synovial fluid of B. animalis BD400-treated CIA rats, were significantly reduced (p < 0.05). The gene expression levels of intestinal barrier proteins (occludin-1, MUC-2, and ZO-1) showed a significant increase (p < 0.05) in B. animalis BD400-treated CIA rats. The oral administration of B. animalis BD400 altered the composition of intestinal microorganisms in CIA rats at the phylum and genus levels, particularly affecting the genus HT002. B. animalis BD400 alleviates RA by down-regulating 1-methyl-L-histidine and urocanate in the histidine metabolism, laying a foundation for the RA prevention.

Conclusion

By affecting genus HT002 and histidine metabolism in the gut microbiota of CIA rats, B. animalis BD400 restored intestinal permeability, inhibited systemic inflammatory response, and ultimately slowed down the development of RA.

Gut Microbiota Interacts with Dietary Habits in Screenings for Early Detection of Colorectal Cancer

BACKGROUND/OBJECTIVES

Gut microbiota interacts with nutrients, which may be relevant to assigning a microbial signature to colorectal cancer (CRC). We aim to evaluate the potential of gut microbiota combined with dietary habits in the early detection of pathological findings related to CRC in the course of a screening program.

METHODOLOGY

The colonoscopy performed on 152 subjects positive for fecal occult blood test showed that 6 subjects had adenocarcinoma, 123 had polyps, and 23 subjects had no pathological findings. Gut microbiota was analyzed by 16S metagenomic. Caret package was used to build the classification models in R.

RESULTS

Random forest (RF) classifier models were used to test the potential of gut microbiota alone or combined with dietary habits as a biomarker to discern between individuals with CRC-related lesions (polyps or adenocarcinoma) versus individuals without pathological findings. RF classifier models yielded an area under the curve of 0.790 using gut microbiota data, 0.710 using dietary habits data, and 0.804 in the combined model including gut microbiota and dietary habits data. The abundance of Suterella, Oscillospirales, Proteobacteria, and Burkholderiales was highly discriminant between groups, together with the consumption of fruit and vegetables and the consumption of carbonated and/or sweetened beverages.

CONCLUSIONS

Our results suggest that the interaction between gut microbiota and dietary habits is relevant when a microbial signature is used as a marker in CRC. Moreover, gut microbiota signature and information about the dietary habits of the individuals seem to be important for improving screening programs for the early detection of CRC.

Mechanisms of gut homeostasis regulating Th17/Treg cell balance in PMOP

Postmenopausal osteoporosis (PMOP) is a metabolic bone disease driven by estrogen deficiency, primarily manifesting as reduced bone mass and heightened fracture risk. Its development is intricately linked to the balance between Th17 and Treg cells. Recent studies have highlighted the significant role of gut homeostasis in PMOP. The gut microbiota profoundly impacts bone health by modulating the host's immune system, metabolic pathways, and endocrine functions. In particular, the regulation of Th17 and Treg cell balance by gut homeostasis plays a pivotal role in the onset and progression of PMOP. Th17 cells secrete pro-inflammatory cytokines that stimulate osteoclast activity, accelerating bone resorption, while Treg cells counteract this process through anti-inflammatory mechanisms, preserving bone mass. The gut microbiota and its metabolites can influence Th17/Treg equilibrium, thereby modulating bone metabolism. Furthermore, the integrity of the gut barrier is critical for systemic immune stability, and its disruption can lead to immune dysregulation and metabolic imbalances. Thus, targeting gut homeostasis to restore Th17/Treg balance offers a novel therapeutic avenue for the prevention and treatment of PMOP.

Molecular Mimicry Between Gut Microbiome and Rheumatoid Arthritis: Current Concepts

Rheumatoid arthritis (RA) represents an autoimmune condition impacted by a combination of genetic and environmental factors, with the gut microbiome (GMB) being one of the influential environmental factors. Patients with RA display notable modifications in the composition of their GMB, characterised by decreased diversity and distinct bacterial alterations. The GMB, comprising an extensive array of approximately 35,000 bacterial species residing within the gastrointestinal tract, has garnered considerable attention as a pivotal contributor to both human health and the pathogenesis of diseases. This article provides an in-depth exploration of the intricate involvement of the GMB in the context of RA. The oral-GMB axis highlights the complex role of bacteria in RA pathogenesis by producing antibodies to citrullinated proteins (ACPAs) through molecular mimicry. Dysbiosis affects Tregs, cytokine levels, and RA disease activity, suggesting that regulating cytokines could be a strategy for managing inflammation in RA. The GMB also has significant implications for drug responses and toxicity, giving rise to the field of pharmacomicrobiomics. The composition of the microbiota can impact the efficacy and toxicity of drugs, while the microbiota's metabolites can influence drug response. Recent research has identified specific bacteria, metabolites, and immune responses associated with RA, offering potential targets for personalised management. However, several challenges, including the variation in microbial composition, establishing causality, accounting for confounding factors, and translating findings into clinical practice, need to be addressed. Microbiome-targeted therapy is still in its early stages and requires further research and standardisation for effective implementation.

Peptide BG From Bitter Gourd (Momordica Charantia) Improves Adjuvant-Induced Arthritis by Modulating the Necroptosis/Neutrophil Extracellular Traps/Inflammation Axis and the Gut Microbiota

Background: BG is a novel bioactive peptide derived from bitter gourd (Momordica charantia), known for its anti-inflammatory and immunomodulatory properties. In the present study, our objective is to investigate the functional roles and mechanisms of BG in the context of rheumatoid arthritis (RA). Methods: A rat model of adjuvant-induced arthritis (AIA) was established by administering complete Freund's adjuvant (CFA). The viability of BG-mediated AIA was evaluated by assessing changes in rat body weight, joint swelling, ankle joint pathology, inflammation, necroptosis, the formation of neutrophil extracellular traps (NETs), and gut microbiota. Results: The results of the study showed that peptide BG was effective in improving weight loss, joint swelling, serum IgM-rheumatoid factor (IgM-RF) level, and pathological injury of ankle joint in rats with AIA. BG administration resulted in a decrease in erythrocyte sedimentation rate, serum C-reactive protein (CRP), and inflammatory factor (interferon-γ (IFN-γ), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α)) in AIA rats. Additionally, the administration of CFA resulted in an increase in the protein levels of myeloperoxidase (MPO), neutrophil elastase (NE), citrullinated histone H3 (CitH3), peptidyl arginine deiminase 4 (PAD4), p-mixed lineage kinase domain-like (p-MLKL), and cleaved caspase 8. However, this increase was found to be inhibited by BG treatment. Furthermore, it has been found that peptide BG possesses the capacity to regulate the species composition structure of the intestinal microbiota, thereby, facilitating the reestablishment of microbial diversity and equilibrium. Conclusion: Peptide BG has demonstrated efficacy in ameliorating AIA through its regulation of the necroptosis/NETs/inflammation axis and the gut microbiota. This finding underscores the potential of BG as a promising therapeutic intervention for RA.

"Pleiotropic" Effects of Antibiotics: New Modulators in Human Diseases

Antibiotics, widely used medications that have significantly increased life expectancy, possess a broad range of effects beyond their primary antibacterial activity. While some are recognized as adverse events, others have demonstrated unexpected benefits. These adjunctive effects, which have been defined as "pleiotropic" in the case of other pharmacological classes, include immunomodulatory properties and the modulation of the microbiota. Specifically, macrolides, tetracyclines, and fluoroquinolones have been shown to modulate the immune system in both acute and chronic conditions, including autoimmune disorders (e.g., rheumatoid arthritis, spondyloarthritis) and chronic inflammatory pulmonary diseases (e.g., asthma, chronic obstructive pulmonary disease). Azithromycin, in particular, is recommended for the long-term treatment of chronic inflammatory pulmonary diseases due to its well-established immunomodulatory effects. Furthermore, antibiotics influence the human microbiota. Rifaximin, for example, exerts a eubiotic effect that enhances the balance between the gut microbiota and the host immune cells and epithelial cells. These pleiotropic effects offer new therapeutic opportunities by interacting with human cells, signaling molecules, and bacteria involved in non-infectious diseases like spondyloarthritis and inflammatory bowel diseases. The aim of this review is to explore the pleiotropic potential of antibiotics, from molecular and cellular evidence to their clinical application, in order to optimize their use. Understanding these effects is essential to ensure careful use, particularly in consideration of the threat of antimicrobial resistance.

Intermittent fasting reduces inflammation and joint damage in a murine model of rheumatoid arthritis: insights from transcriptomic and metagenomic analyses

BACKGROUND

Intermittent fasting (IF) has shown benefits in various pathological conditions. Although its anti-inflammatory potential has been recognized, its effects on the mechanism underlying rheumatoid arthritis (RA) remain insufficiently characterized. This study aimed to investigate the effects of IF in a murine model of RA.

METHODS

Collagen-induced arthritis (CIA) was developed in sixteen male DBA/1 mice, randomly assigned to two groups, with one undergoing IF every other day for four weeks. The effects of IF on joint inflammation and remodeling were evaluated clinically, histologically, and through tomography. Transcriptomic changes were characterized using expression microarrays, validated by RT-qPCR, and confirmed by immunohistochemistry. Additionally, modifications in gut microbiota were assessed through 16 S sequencing.

RESULTS

Mice subjected to IF significantly reduced the incidence and severity of clinical arthritis. Histological and radiographic assessments confirmed a decrease in inflammation and joint damage. Transcriptomic analysis revealed that IF led to the upregulation of 364 genes and the downregulation of 543 genes, with notable reductions in inflammatory signaling pathways associated with RA-related genes, including Cd72, Cd79a, Ifna, Il33, and Bglap 2. Notably, IL33 emerged as a pivotal mediator in the inflammatory processes mitigated by fasting. Key regulators associated with IF effects, such as CEBPA, FOXO1, HIF1A, PPARG, and PPARA, were identified, indicating a complex interplay between metabolic and inflammatory pathways. Furthermore, differential expression of microRNAs and lncRNAs, including miR-15b, miR-103-2, miR-302a, miR-6985, and miR- 5624, was observed. Metagenomic analysis indicated that IF enhanced the abundance and diversity of the gut microbiome, explicitly promoting anti-inflammatory bacterial populations, notably within the genus Ruminococcaceae.

CONCLUSION

Our findings suggest that IF exerts significant anti-inflammatory and immunoregulatory effects in the context of CIA. Given its non-risky nature, further investigation into the potential benefits of IF in patients with RA is warranted.

CLINICAL TRIAL NUMBER

Not applicable.

A Case Series Report on the Effect of Tofacitinib on Joint Inflammation and Gut Microbiota Composition in Psoriatic Arthritis Patients Naive to Biologic Agents

INTRODUCTION

Psoriatic arthritis (PsA) is a complex condition within the Spondyloarthritis (SpA) group. Recent studies have focused on the important role of the intestinal microbiota in maintaining immunological homeostasis, highlighting how intestinal dysbiosis may act as a trigger for autoimmune diseases. Tofacitinib is a Janus kinase inhibitor (JAK-i) with proven efficacy for the treatment of both rheumatoid arthritis and PsA. However, there is a lack of data on its ability to reduce joint remission through ultrasonography (US) and the effects it might have on the composition of the gut microbiota.

METHODS

Here, we present a case series of seven bio-naïve PsA patients who received tofacitinib treatment and were followed up for 12 months. The clinical response was assessed using validated scores (DAPSA, ASDAS, and BASDAI), laboratory tests, and US assessment of the target joint and enthesis. Finally, we evaluated changes in the composition of the intestinal microbiota using next-generation sequencing analysis of fecal samples.

RESULTS

The patients in the study showed a significant improvement in all clinical scores used; this improvement was also confirmed by a significant reduction in the US synovitis scores. The data on the microbiota analysis suggested that the effectiveness of tofacitinib in ameliorating PsA activity was associated with a relevant modification of some gut bacterial lineages. No cases of severe adverse effects were reported.

CONCLUSIONS

Treatment with tofacitinib proved to be effective, safe and capable of varying the composition of the gut microbiota by selecting bacterial strains considered beneficial in immune modulation.

Mechanism of action of Nrf2 and its related natural regulators in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovitis that can lead to joint deformities. To date, more than 18 million individuals worldwide have been diagnosed with RA, making it one of the most prevalent autoimmune diseases globally and posing a significant threat to public health and safety. Due to the complex pathogenesis of the disease, which involves autoimmunity, genetics, inflammation and oxidative stress in the body's tissues, the current drug therapy generally targets a single molecule, and effective and efficient drugs involving multiple levels and targets are lacking; thus, there is an urgent need for high-quality research and treatment in this field. Nuclear transcription factor erythroid 2-associated factor 2 (Nrf2) plays a crucial role in cellular resistance to oxidative stress and electrophilic attacks and is a potential pharmacological target for chronic disease treatment. While currently no drugs that target Nrf2 have been approved specifically for RA treatment, such an approach holds great significance. In recent years, the use of natural products to treat RA and other chronic conditions has become increasingly widespread because of their superior efficacy and minimal side effects. Therefore, this article provides a review of the mechanism of Nrf2 in RA and summarizes natural products that target Nrf2 and its associated pathways in the treatment of RA, aiming to offer new insights and strategies for the prevention and management of RA.

Butyrate: a bridge between intestinal flora and rheumatoid arthritis

In patients with rheumatoid arthritis (RA), intestinal flora imbalance and butyrate metabolism disorders precede clinical arthritis and are associated with the pathogenesis of RA. This imbalance can alter the immunology and intestinal permeability of the intestinal mucosa, leading to damage to the intestinal barrier. In this context, bacteria and their metabolites can enter the bloodstream and reach the distant target tissues of the host, resulting in local inflammation and aggravating arthritis. Additionally, arthritis is also exacerbated by bone destruction and immune tolerance due to disturbed differentiation of osteoclasts and adaptive immune cells. Of note, butyrate is a metabolite of intestinal flora, which not only locally inhibits intestinal immunity and targets zonulin and tight junction proteins to alleviate intestinal barrier-mediated arthritis but also inhibits osteoclasts and autoantibodies and balances the immune responses of T and B lymphocytes throughout the body to repress bone erosion and inflammation. Therefore, butyrate is a key intermediate linking intestinal flora to the host. As a result, restoring the butyrate-producing capacity of intestinal flora and using exogenous butyrate are potential therapeutic strategies for RA in the future.

The rheumatoid arthritis gut microbial biobank reveals core microbial species that associate and effect on host inflammation and autoimmune responses

Gut microbiota dysbiosis has been implicated in rheumatoid arthritis (RA) and influences disease progression. Although molecular and culture-independent studies revealed RA patients harbored a core microbiome and had characteristic bacterial species, the lack of cultured bacterial strains had limited investigations on their functions. This study aimed to establish an RA-originated gut microbial biobank (RAGMB) that covers and further to correlates and validates core microbial species on clinically used and diagnostic inflammation and immune indices. We obtained 3200 bacterial isolates from fecal samples of 20 RA patients with seven improved and 11 traditional bacterial cultivation methods. These isolates were phylogenetically identified and selected for RAGMB. The RAGMB harbored 601 bacterial strains that represented 280 species (including 43 novel species) of seven bacterial phyla. The RAGMB covered 93.2% at species level of medium- and high-abundant (relative abundances ≥0.2%) RA gut microbes, and included four rare species of the phylum Synergistota. The RA core gut microbiome was defined and composed of 20 bacterial species. Among these, Mediterraneibacter tenuis and Eubacterium rectale were two species that statistically and significantly correlated with clinically used diagnostic indices such as erythrocyte sedimentation rate (ESR) and IL-10. Thus, M. tenuis and E. rectale were selected for experimental validation using DSS-treated and not DSS-treated mice model. Results demonstrated both M. tenuis and E. rectale exacerbated host inflammatory responses, including shortened colon length and increased spleen weight, decreased IL-10 and increased IL-17A levels in plasma. Overall, we established the RAGMB, defined the RA core microbiome, correlated and demonstrated core microbial species effected on host inflammatory and immune responses. This work provides diverse gut microbial resources for future studies on RA etiology and potential new targets for new biomedical practices.

The gut homeostasis-immune system axis: novel insights into rheumatoid arthritis pathogenesis and treatment

Rheumatoid arthritis is a widely prevalent autoimmune bone disease that imposes a significant burden on global healthcare systems due to its increasing incidence. In recent years, attention has focused on the interaction between gut homeostasis and the immune system, particularly in relation to bone health. Dysbiosis, which refers to an imbalance in the composition and function of the gut microbiota, has been shown to drive immune dysregulation through mechanisms such as the release of pro-inflammatory metabolites, increased gut permeability, and impaired regulatory T cell function. These factors collectively contribute to immune system imbalance, promoting the onset and progression of Rheumatoid arthritis. Dysbiosis induces both local and systemic inflammatory responses, activating key pro-inflammatory cytokines such as tumor necrosis factor-alpha, Interleukin-6, and Interleukin-17, which exacerbate joint inflammation and damage. Investigating the complex interactions between gut homeostasis and immune regulation in the context of Rheumatoid arthritis pathogenesis holds promise for identifying new therapeutic targets, revealing novel mechanisms of disease progression, and offering innovative strategies for clinical treatment.

Mendelian randomization identifies causal associations between GWAS-associated bacteria and their metabolites and rheumatoid arthritis

Background

Accumulating evidence suggests that an imbalance of gut microbiota is commonly observed in patients with rheumatoid arthritis (RA). However, it remains unclear whether gut microbiota dysbiosis is a cause or consequence of RA, and the mechanisms by which gut dysbiosis contributes to RA have not been fully understood. This study aimed to investigate the causal relationship between gut microbiota and metabolites with RA.

Methods

A two-sample Mendelian randomization analysis was performed to estimate the causality of gut microbiota and metabolites on RA. A genome-wide association study (GWAS) of 211 gut microbiota and 217 metabolites was used as the exposure, whereas RA was treated as the outcome. Inverse variance weighted (IVW) was regarded as the primary approach for calculating causal estimates. MR Egger method, Weighted median method, Simple mode method, and weighted mode method were used for sensitive analysis. Metabolic pathway analysis was performed via the web-based Metaconflict 5.0. Additionally, an animal study was undertaken to evaluate the results inferred by Mendelian randomization.

Result

This study indicated that six gut microbiota taxa (RuminococcaceaeUCG013, Erysipelotrichia, Erysipelotrichaceae, Erysipelotrichales, Clostridia, and Veillonellaceae) were estimated to exert a positive impact on RA. Conversely, seven gut microbiota taxa (Oxalobacter, Cyanobacteria, RuminococcaceaeUCG002, LachnospiraceaeUCG010, Christensenellaceae, Oxalobacteraceae, Anaerostipes) were estimated to exert a negative impact on RA. Three metabolites, namely indole-3-propionate (IPA), glycine and sphingomyelin (SM 16:1), were found to be linked to lower RA risk, while five metabolites (argininosuccinate, CE 20_4, TAG 58_8, PC 40_6, and LPC 20_4) were linked to higher RA risk. Additionally, four metabolic pathways were identified by metabolic pathway analysis. The collagen-induced arthritis (CIA) rats exhibited a higher relative abundance of Class_Clostridia and a lower abundance of Genus_Lachnospiraceae (p < 0.05) than the healthy controls.

Conclusion

This study identified causal associations between specific gut microbiota, metabolites, and RA. These findings support the significant role of gut microbiota and metabolites in RA pathogenesis.

Identification and comparison of intestinal microbial diversity in patients at different stages of hepatic cystic echinococcosis

There is a significant focus on the role of the host microbiome in different outcomes of human parasitic diseases, including cystic echinococcosis (CE). This study was conducted to identify the intestinal microbiome of patients with CE at different stages of hydatid cyst compared to healthy individuals. Stool samples from CE patients as well as healthy individuals were collected. The samples were divided into three groups representing various stages of hepatic hydatid cyst: active (CE1 and CE2), transitional (CE3), and inactive (CE4 and CE5). One family member from each group was selected to serve as a control. The gut microbiome of patients with different stages of hydatid cysts was investigated using metagenomic next-generation amplicon sequencing of the V3-V4 region of the 16S rRNA gene. In this study, we identified 4862 Operational Taxonomic Units from three stages of hydatid cysts in CE patients and healthy individuals with a combined frequency of 2,955,291. The most abundant genera observed in all the subjects were Blautia, Agathobacter, Faecalibacterium, Bacteroides, Bifidobacterium, and Prevotella. The highest microbial frequency was related to inactive forms of CE, and the lowest frequency was observed in the group with active forms. However, the lowest OTU diversity was found in patients with inactive cysts compared with those with active and transitional cyst stages. The genus Agatobacter had the highest OTU frequency. Pseudomonas, Gemella, and Ligilactobacillus showed significant differences among the patients with different stages of hydatid cysts. Additionally, Anaerostipes and Candidatus showed significantly different reads in CE patients compared to healthy individuals. Our findings indicate that several bacterial genera can play a role in the fate of hydatid cysts in patients at different stages of the disease.

Immunomodulatory Effects of a Probiotic Mixture: Alleviating Colitis in a Mouse Model through Modulation of Cell Activation Markers and the Gut Microbiota

Ulcerative colitis (UC) is a persistent inflammatory intestinal disease that consistently affects the colon and rectum. Its exact cause remains unknown. UC causes a considerable challenge in healthcare, prompting research for novel therapeutic strategies. Although probiotics have gained popularity as possible candidates for managing UC, studies are still ongoing to identify the best probiotics or probiotic mixtures for clinical applications. This study aimed to determine the efficacy of a multi-strain probiotic mixture in mitigating intestinal inflammation in a colitis mouse model induced by dextran sulfate sodium. Specifically, a multi-strain probiotic mixture consisting of Tetragenococcus halophilus and Eubacterium rectale was used to study its impact on colitis symptoms. Anti-inflammatory effects were evaluated using ELISA and flow cytometry. The configuration of gut microbial communities was determined using 16S rRNA metagenomic analysis. According to this study, colitis mice treated with the probiotic mixture experienced reduced weight loss and significantly less colonic shortening compared to untreated mice. Additionally, the treated mice exhibited increased levels of forkhead box P3 (Foxp3) and interleukin 10, along with decreased expression of dendritic cell activation markers, such as CD40+, CD80+, and CD83+, in peripheral blood leukocytes and intraepithelial lymphocytes. Furthermore, there was a significant decrease in the frequencies of CD8+N.K1.1+ cells and CD11b+Ly6G+ cells. In terms of the gut microbiota, probiotic-mixture treatment of colitis mice significantly increased the abundance of the phyla Actinobacteria and Verrucomicrobia (p < 0.05). These results provide valuable insights into the therapeutic promise of multi-strain probiotics, shedding light on their potential to alleviate colitis symptoms. This research contributes to the ongoing exploration of effective probiotic interventions for managing inflammatory bowel disease.

Nature of the Association between Rheumatoid Arthritis and Cervical Cancer and Its Potential Therapeutic Implications

It is now established that patients with rheumatoid arthritis (RA) have an increased risk of developing cervical cancer (CC) or its precursor, cervical intraepithelial neoplasia (CIN). However, the underlying mechanisms of this association have not been elucidated. RA is characterized by unresolved chronic inflammation. It is suggested that human papillomavirus (HPV) infection in RA patients exacerbates inflammation, increasing the risk of CC. The tumor microenvironment in RA patients with CC is also marked by chronic inflammation, which aggravates the manifestations of both conditions. Gut and vaginal dysbiosis are also considered potential mechanisms that contribute to the chronic inflammation and aggravation of RA and CC manifestations. Numerous clinical and pre-clinical studies have demonstrated the beneficial effects of various nutritional approaches to attenuate chronic inflammation, including polyunsaturated fatty acids and their derivatives, specialized pro-resolving mediators (SPMs), probiotics, prebiotics, and certain diets. We believe that successful resolution of chronic inflammation and correction of dysbiosis, in combination with current anti-RA and anti-CC therapies, is a promising therapeutic approach for RA and CC. This approach could also reduce the risk of CC development in HPV-infected RA patients.

Bibliometric analysis of global research trends between gut microbiota and breast cancer: from 2013 to 2023

Background

Breast cancer is the most prevalent cancer globally and is associated with significant mortality. Recent research has provided crucial insights into the role of gut microbiota in the onset and progression of breast cancer, confirming its impact on the disease's management. Despite numerous studies exploring this relationship, there is a lack of comprehensive bibliometric analyses to outline the field's current state and emerging trends. This study aims to fill that gap by analyzing key research directions and identifying emerging hotspots.

Method

Publications from 2013 to 2023 were retrieved from the Web of Science Core Collection database. The VOSviewer, R language and SCImago Graphica software were utilized to analyze and visualize the volume of publications, countries/regions, institutions, authors, and keywords in this field.

Results

A total of 515 publications were included in this study. The journal Cancers was identified as the most prolific, contributing 21 papers. The United States and China were the leading contributors to this field. The University of Alabama at Birmingham was the most productive institution. Peter Bai published the most papers, while James J. Goedert was the most cited author. Analysis of highly cited literature and keyword clustering confirmed a close relationship between gut microbiota and breast cancer. Keywords such as "metabolomics" and "probiotics" have been prominently highlighted in the keyword analysis, indicating future research hotspots in exploring the interaction between metabolites in the breast cancer microenvironment and gut microbiota. Additionally, these keywords suggest significant interest in the therapeutic potential of probiotics for breast cancer treatment.

Conclusion

Research on the relationship between gut microbiota and breast cancer is expanding. Attention should be focused on understanding the mechanisms of their interaction, particularly the metabolite-microbiota-breast cancer crosstalk. These insights have the potential to advance prevention, diagnosis, and treatment strategies for breast cancer. This bibliometric study provides a comprehensive assessment of the current state and future trends of research in this field, offering valuable perspectives for future studies on gut microbiota and breast cancer.

Gut microbiome-immune interactions and their role in rheumatoid arthritis development

Objective

The primary objective is to study the impact of gut microbiota and their interactions with diverse immunological markers on the development of rheumatoid arthritis.

Methods

This study was performed in Astana, Kazakhstan, and included 77 Kazakh female patients older than 18 years, who met the American College of Rheumatology 2010 classification criteria for rheumatoid arthritis (RA), and 113 healthy controls. The DNA was extracted from fecal samples obtained from all study participants for subsequent sequencing at the 16S rRNA gene V1-V3 locus, facilitating the analysis of the gut microbiome. The Multiplex immunoassay was employed to measure the concentrations of inflammatory cytokines, chemokines, and immunoglobulins in both fecal and plasma samples.

Results

Our taxonomic analysis revealed significant differences in the composition of the gut microbiota between the healthy control cohort and the cohort with rheumatoid arthritis RA. Alpha diversity was significantly lower in the RA group. Lachnospiraceae were the most abundant taxon and found to be crucial, showing correlations with immunological markers such as IL5. Additionally, Lachnospiraceae and Oscillospiraceae exhibited the most predictable power and distinguished the composition of both study groups.

Conclusion

Our study identifies key differences in the gut microbiome of RA patients, revealing distinct microbial patterns and specific taxa abundance. We highlight potential biomarkers in immunological and bacterial pathways, offering insights into RA development and indicating possibilities for personalized treatment.

Exploring the Role of the Microbiome in Rheumatoid Arthritis-A Critical Review

Rheumatoid arthritis (RA) is a chronic, autoimmune rheumatic disease characterized by synovial joint inflammation with subsequent destruction as well as systemic manifestation, leading to impaired mobility and impaired quality of life. The etiopathogenesis of RA is still unknown, with genetic, epigenetic and environmental factors (incl. tobacco smoking) contributing to disease susceptibility. The link between genetic factors like "shared epitope alleles" and the development of RA is well known. However, why only some carriers have a break in self-tolerance and develop autoimmunity still needs to be clarified. The presence of autoantibodies in patients' serum months to years prior to the onset of clinical manifestations of RA has moved the focus to possible epigenetic factors, including environmental triggers that could contribute to the initiation and perpetuation of the inflammatory reaction in RA. Over the past several years, the role of microorganisms at mucosal sites (i.e., microbiome) has emerged as an essential mediator of inflammation in RA. An increasing number of studies have revealed the microbial role in the immunopathogenesis of autoimmune rheumatic diseases. Interaction between the host immune system and microbiota initiates loss of immunological tolerance and autoimmunity. The alteration in microbiome composition, the so-called dysbiosis, is associated with an increasing number of diseases. Immune dysfunction caused by dysbiosis triggers and sustains chronic inflammation. This review aims to provide a critical summary of the literature findings related to the hypothesis of a reciprocal relation between the microbiome and the immune system. Available data from studies reveal the pivotal role of the microbiome in RA pathogenesis.

Gut microbiota regulation of T lymphocyte subsets during systemic lupus erythematosus

BACKGROUND

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by disturbance of pro-inflammatory and anti-inflammatory lymphocytes. Growing evidence shown that gut microbiota participated in the occurrence and development of SLE by affecting the differentiation and function of intestinal immune cells. The purpose of this study was to investigate the changes of gut microbiota in SLE and judge its associations with peripheral T lymphocytes.

METHODS

A total of 19 SLE patients and 16 HCs were enrolled in this study. Flow cytometry was used to detect the number of peripheral T lymphocyte subsets, and 16 s rRNA was used to detect the relative abundance of gut microbiota. Analyzed the correlation between gut microbiota with SLEDAI, ESR, ds-DNA and complement. SPSS26.0 software was used to analyze the experimental data. Mann-Whitney U test was applied to compare T lymphocyte subsets. Spearman analysis was used for calculating correlation.

RESULTS

Compared with HCs, the proportions of Tregs (P = 0.001), Tfh cells (P = 0.018) and Naïve CD4 + T cells (P = 0.004) significantly decreased in SLE patients, and proportions of Th17 cells (P = 0.020) and γδT cells (P = 0.018) increased in SLE. The diversity of SLE patients were significantly decreased. Addition, there were 11 species of flora were discovered to be distinctly different in SLE group (P < 0.05). In the correlation analysis of SLE, Tregs were positively correlated with Ruminococcus2 (P = 0.042), Th17 cells were positively correlated with Megamonas (P = 0.009), γδT cells were positively correlated with Megamonas (P = 0.003) and Streptococcus (P = 0.004), Tfh cells were positively correlated with Bacteroides (P = 0.040), and Th1 cells were negatively correlated with Bifidobacterium (P = 0.005). As for clinical indicators, the level of Tregs was negatively correlated with ESR (P = 0.031), but not with C3 and C4, and the remaining cells were not significantly correlated with ESR, C3 and C4.

CONCLUSION

Gut microbiota and T lymphocyte subsets of SLE changed and related to each other, which may break the immune balance and affect the occurrence and development of SLE. Therefore, it is necessary to pay attention to the changes of gut microbiota and provide new ideas for the treatment of SLE.

Fecal microbiota transplantation in autoimmune diseases - An extensive paper on a pathogenetic therapy

The role of infections in the pathogenesis of autoimmune diseases has long been recognized and reported. In addition to infectious agents, the internal composition of the "friendly" living bacteria, (microbiome) and its correlation to immune balance and dysregulation have drawn the attention of researchers for decades. Nevertheless, only recently, scientific papers regarding the potential role of transferring microbiome from healthy donor subjects to patients with autoimmune diseases has been proposed. Fecal microbiota transplantation or FMT, carries the logic of transferring microorganisms responsible for immune balance from healthy donors to individuals with immune dysregulation or more accurately for our paper, autoimmune diseases. Viewing the microbiome as a pathogenetic player allows us to consider FMT as a pathogenetic-based treatment. Promising results alongside improved outcomes have been demonstrated in patients with different autoimmune diseases following FMT. Therefore, in our current extensive review, we aimed to highlight the implication of FMT in various autoimmune diseases, such as inflammatory bowel disease, autoimmune thyroid and liver diseases, systemic lupus erythematosus, and type 1 diabetes mellitus, among others. Presenting all the aspects of FMT in more than 12 autoimmune diseases in one paper, to the best of our knowledge, is the first time presented in medical literature. Viewing FMT as such could contribute to better understanding and newer application of the model in the therapy of autoimmune diseases, indeed.

Treatment for Rheumatoid Arthritis Associated With Alterations in the Gastrointestinal Microbiota

OBJECTIVE

Emerging research suggests that rheumatoid arthritis (RA) is associated with intestinal dysbiosis. This prospective pilot study evaluates changes in intestinal microbial composition in patients with RA initiating treatment with either methotrexate (MTX) or a tumor necrosis factor inhibitor (TNFi).

METHODS

Consecutive patients, fulfilling the 2010 American College of Rheumatology/EULAR classification criteria for RA, who started treatment with either MTX or TNFi delivered a stool sample upon initiation of immunosuppression and 3 months later. A 16S ribosomal RNA gene-based validated microbiota test (GA-map Dysbiosis Index Score [DIS], Genetic Analysis, Oslo, Norway) was used to evaluate for the presence and degree of dysbiosis. Fecal levels of Prevotella copri (P. copri) were analyzed by custom-made quantitative polymerase chain reaction. Changes in microbial composition were analyzed in relation to changes in disease activity, as measured by the disease activity score based on 28-joint counts, using C-reactive protein.

RESULTS

At baseline, dysbiosis was present in 33 of 50 (66%) participants and more common in participants with more than 2 years of disease duration (P = 0.019). At the 3-month follow-up, 27 of 50 (54%) were good treatment responders and the DIS had improved in 14 of 50 (28%). Participants initiating TNFi more often exhibited improvement in the DIS compared with those initiating MTX (P = 0.031). P. copri was identified in 32 of 50 (64%) at baseline. An improvement in disease activity score based on 28-joint counts, using C-reactive protein was associated with a simultaneous decrease in P. copri abundance (rs = 0.30, P = 0.036).

CONCLUSION

This study affirms that dysbiosis is a feature of RA. Although patients were not randomized to MTX or TNFi, the findings suggest that specific therapies may differentially modulate the gastrointestinal microbiota in RA. The association between P. copri and treatment response requires further study.

Fufang Duzheng tablet attenuates adjuvant rheumatoid arthritis by inhibiting arthritis inflammation and gut microbiota disturbance in rats

Objective

To explore the treatment effect and potential mechanism on gut microbiota, nutrition, and metabolism of Fufang Duzheng Tablet (DZGP) on rheumatoid arthritis (RA).

Methods

Collagen-induced arthritis rats' models were established and divided into three groups: model control group (FK), DZGP group (FZ, 0.45 g/kg/d), and methotrexate group (FM, 1.35 mg/kg), which were treated by gavage for 28 days. The physiopathologic changes of joints and body weight in each group were recorded; the morphology of synovial and ankle tissues was observed by hematoxylin-eosin staining, and the level of serum TNF-α and IL-1β was tested by ELISA. UPLC/MS-MS and network pharmacological analysis were used to identify the serum components, and 16S rDNA sequencing analysis was applied to the intestinal contents of rats.

Results

DZGP treatment significantly alleviated arthritis symptoms, pathological manifestations, toe thickness, and TNF-α and IL-1β levels in RA rats. We identified 105 metabolites and 18 components in the serum of DZGP-group rats. The main therapeutic targets of DZGP for anti-RA were TP53, epidermal growth factor receptor, and AKT1. Molecular docking showed that there was good binding efficiency between core components and main targets. 16S rDNA sequencing showed that DZGP treatment regulated the structure of the gut microbiota.

Conclusion

DZGP showed a good anti-inflammatory effect on RA and played an important role in improving the structure of the gut microbiota in RA rats.

Unveiling Novel Drug Targets and Emerging Therapies for Rheumatoid Arthritis: A Comprehensive Review

Rheumatoid arthritis (RA) is a chronic debilitating autoimmune disease, that causes joint damage, deformities, and decreased functionality. In addition, RA can also impact organs like the skin, lungs, eyes, and blood vessels. This autoimmune condition arises when the immune system erroneously targets the joint synovial membrane, resulting in synovitis, pannus formation, and cartilage damage. RA treatment is often holistic, integrating medication, physical therapy, and lifestyle modifications. Its main objective is to achieve remission or low disease activity by utilizing a "treat-to-target" approach that optimizes drug usage and dose adjustments based on clinical response and disease activity markers. The primary RA treatment uses disease-modifying antirheumatic drugs (DMARDs) that help to interrupt the inflammatory process. When there is an inadequate response, a combination of biologicals and DMARDs is recommended. Biological therapies target inflammatory pathways and have shown promising results in managing RA symptoms. Close monitoring for adverse effects and disease progression is critical to ensure optimal treatment outcomes. A deeper understanding of the pathways and mechanisms will allow new treatment strategies that minimize adverse effects and maintain quality of life. This review discusses the potential targets that can be used for designing and implementing precision medicine in RA treatment, spotlighting the latest breakthroughs in biologics, JAK inhibitors, IL-6 receptor antagonists, TNF blockers, and disease-modifying noncoding RNAs.

Exploring the significance of microbiota metabolites in rheumatoid arthritis: uncovering their contribution from disease development to biomarker potential

Rheumatoid arthritis (RA) is a multifaceted autoimmune disorder characterized by chronic inflammation and joint destruction. Recent research has elucidated the intricate interplay between gut microbiota and RA pathogenesis, underscoring the role of microbiota-derived metabolites as pivotal contributors to disease development and progression. The human gut microbiota, comprising a vast array of microorganisms and their metabolic byproducts, plays a crucial role in maintaining immune homeostasis. Dysbiosis of this microbial community has been linked to numerous autoimmune disorders, including RA. Microbiota-derived metabolites, such as short-chain fatty acids (SCFAs), tryptophan derivatives, Trimethylamine-N-oxide (TMAO), bile acids, peptidoglycan, and lipopolysaccharide (LPS), exhibit immunomodulatory properties that can either exacerbate or ameliorate inflammation in RA. Mechanistically, these metabolites influence immune cell differentiation, cytokine production, and gut barrier integrity, collectively shaping the autoimmune milieu. This review highlights recent advances in understanding the intricate crosstalk between microbiota metabolites and RA pathogenesis and also discusses the potential of specific metabolites to trigger or suppress autoimmunity, shedding light on their molecular interactions with immune cells and signaling pathways. Additionally, this review explores the translational aspects of microbiota metabolites as diagnostic and prognostic tools in RA. Furthermore, the challenges and prospects of translating these findings into clinical practice are critically examined.

Current Approaches to Prevent or Reverse Microbiome Dysbiosis in Chronic Inflammatory Rheumatic Diseases

Advances in knowledge of the microbiome and its relationship with the immune system have led to a better understanding of the pathogenesis of chronic inflammatory rheumatic diseases (CIRD). Indeed, the microbiome dysbiosis now occupies a particular place with implications for the determinism and clinical expression of CIRD, as well as the therapeutic response of affected patients. Several approaches exist to limit the impact of the microbiome during CIRD. This review aimed to present current strategies to prevent or reverse microbiome dysbiosis based on existing knowledge, in order to provide practical information to healthcare professionals treating patients suffering from CIRD.

Quality of evidence supporting the role of probiotics for rheumatoid arthritis: an overview of systematic reviews

Background

To evaluate the methodological quality, report quality, and evidence quality of meta-analysis (MA) and systematic review (SR) on the efficacy of probiotics in the treatment of rheumatoid arthritis (RA).

Methods

Databases were used to identify eligible SRs/MAs until February 12, 2024. The methodological quality of the studies was assessed using AMSTAR-2 tool, the quality of the literature reports was scored using PRISMA checklists, and the quality of the evidence was graded using GRADE system.

Results

Seven reviews including 21 outcomes were included. Methodological quality of the included reviews was of general low, and the entries with poor scores were 2, 4, and 7. By PRISMA checklists, there were some reporting deficiencies, and quality problems were mainly reflected in the reporting registration and protocol, comprehensive search strategy and additional analysis. GRADE results elevated the quality of evidence to be low or very low overall.

Conclusions

Probiotics may have a therapeutic effect on RA, based on the evidence provided by the SRs/MAs in this overview. Nevertheless, there is still a lack of conclusive evidence due to methodological limitations in the included research. To make trustworthy judgments regarding the efficacy of probiotics in the treatment of RA, more large-scale, high-quality randomized controlled trials are still required.

High fat diet increases the severity of collagen-induced arthritis in mice by altering the gut microbial community

OBJECTIVES

Research has demonstrated that obesity may be associated with rheumatoid arthritis (RA). In addition, gut microbiota and its metabolites contribute to the occurrence and development of RA and obesity. However, the mechanism by which obesity affects RA remains unclear. In this study, we aimed to investigate whether gut microbiota and their metabolites alter the effects of high fat diet (HFD) on the severity of collagen-induced arthritis (CIA) in mice.

METHODS

Briefly, mice were divided into normal group (N), CIA model group (C), HFD group (T), and HFD CIA group (CT). Hematoxylin and Eosin staining(HE) and Safranin O-fast green staining were conducted, and levels of blood lipid and inflammatory cytokines were measured. 16S rDNA sequencing technique and liquid chromatography-mass spectrometry (LC-MS)-based metabolomics were performed to explore changes in the microbiota structure to further reveal the pathomechanism of HFD on CIA.

RESULTS

HFD aggravated the severity of CIA in mice. The CT group had the highest proportion of microbial abundance of Blautia, Oscillibacter, Ruminiclostridium-9, and Lachnospiraceae UCG 006 at the genus level, but had a lower proportion of Alistipes. Additionally, the fecal metabolic phenotype of the combined CT group shows significant changes, with differential metabolites enriched in 9 metabolic pathways, including primary bile acid biosynthesis, arginine biosynthesis, sphingolipid metabolism, purine metabolism, linoleic acid metabolism, oxytocin signaling pathway, aminoacyl-tRNA biosynthesis, the pentose phosphate pathway, and sphingolipid signaling pathway. Correlation analysis revealed that some of the altered gut microbiota genera were strongly correlated with changes in fecal metabolites, total cholesterol (TC), triglyceride (TG), and inflammatory cytokine levels.

CONCLUSIONS

This study shows that HFD may aggravate inflammatory reaction in CIA mice by altering the gut microbiota and metabolic pathways.

Reassessing Gout Management through the Lens of Gut Microbiota

Gout, recognized as the most common form of inflammatory arthritis, arises from the accumulation of uric acid crystals, leading to intense pain, particularly in the big toe. This condition has traditionally been associated with the overproduction or reduced clearance of uric acid. Recent studies, however, have underscored the significant role of the gut microbiota in uric acid metabolism, impacting both its production and elimination. This emerging understanding suggests that maintaining gut health could offer innovative approaches to treating gout, complementing traditional dietary and pharmacological interventions. It highlights the potential of probiotics or microbiome-based therapies, indicating a future where treatments are tailored to an individual’s microbiome. This offers a fresh perspective on gout management and underscores the broader influence of the microbiota on health and disease.

Chondroitin sulfate-modified tragacanth gum-gelatin composite nanocapsules loaded with curcumin nanocrystals for the treatment of arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease of yet undetermined etiology that is accompanied by significant oxidative stress, inflammatory responses,  and damage to joint tissues. In this study, we designed chondroitin sulfate (CS)-modified tragacanth gum-gelatin composite nanocapsules (CS-Cur-TGNCs) loaded with curcumin nanocrystals (Cur-NCs), which rely on the ability of CS to target CD44 to accumulate drugs in inflamed joints. Cur was encapsulated in the form of nanocrystals into tragacanth gum-gelatin composite nanocapsules (TGNCs) by using an inborn microcrystallization method, which produced CS-Cur-TGNCs with a particle size of approximately 80 ± 11.54 nm and a drug loading capacity of 54.18 ± 5.17%. In an in vitro drug release assay, CS-Cur-TGNCs showed MMP-2-responsive properties. During the treatment of RA, CS-Cur-TGNCs significantly inhibited oxidative stress, promoted the polarization of M2-type macrophages to M1-type macrophages, and decreased the expression of inflammatory factors (TNF-α, IL-1β, and IL-6). In addition, it also exerted excellent anti-inflammatory effects, and significantly alleviated the swelling of joints during the treatment of gouty arthritis (GA). Therefore, CS-Cur-TGNCs, as a novel drug delivery system, could lead to new ideas for clinical therapeutic regimens for RA and GA.

Unraveling the intricate dance of the Mediterranean diet and gut microbiota in autoimmune resilience

The nutritional habits regulate the gut microbiota and increase risk of an autoimmune disease. Western diet is rich in sugars, meat, and poly-unsaturated fatty acids, which lead to dysbiosis of intestinal microbiota, disruption of gut epithelial barrier and chronic mucosal inflammation. In contrast, the Mediterranean Diet (MedDiet) is abundant in ω3 fatty acids, fruits, and vegetables, possessing anti-inflammatory properties that contribute to the restoration of gut eubiosis. Numerous studies have extensively examined the impact of MedDiet and its components on both health and various disease states. Additionally, specific investigations have explored the correlation between MedDiet, microbiota, and the risk of autoimmune diseases. Furthermore, the MedDiet has been linked to a reduced risk of cardiovascular diseases, playing a pivotal role in lowering mortality rates among individuals with autoimmune diseases and comorbidities. The aim of the present review is to specifically highlight current knowledge regarding possible interactions of MedDiet with the patterns of intestinal microbiota focusing on autoimmunity and a blueprint through dietary modulations for the prevention and management of disease's activity and progression.

Review: A Contemporary, Multifaced Insight into Psoriasis Pathogenesis

Psoriasis is a chronic recurrent inflammatory autoimmune pathology with a significant genetic component and several interferences of immunological cells and their cytokines. The complex orchestration of psoriasis pathogenesis is related to the synergic effect of immune cells, polygenic alterations, autoantigens, and several other external factors. The major act of the IL-23/IL-17 axis, strongly influencing the inflammatory pattern established during the disease activity, is visible as a continuous perpetuation of the pro-inflammatory response and keratinocyte activation and proliferation, leading to the development of psoriatic lesions. Genome-wide association studies (GWASs) offer a better view of psoriasis pathogenic pathways, with approximately one-third of psoriasis's genetic impact on psoriasis development associated with the MHC region, with genetic loci located on chromosome 6. The most eloquent genetic factor of psoriasis, PSORS1, was identified in the MHC I site. Among the several factors involved in its complex etiology, dysbiosis, due to genetic or external stimulus, induces a burst of pro-inflammatory consequences; both the cutaneous and gut microbiome get involved in the psoriasis pathogenic process. Cutting-edge research studies and comprehensive insights into psoriasis pathogenesis, fostering novel genetic, epigenetic, and immunological factors, have generated a spectacular improvement over the past decades, securing the path toward a specific and targeted immunotherapeutic approach and delayed progression to inflammatory arthritis. This review aimed to offer insight into various domains that underline the pathogenesis of psoriasis and how they influence disease development and evolution. The pathogenesis mechanism of psoriasis is multifaceted and involves an interplay of cellular and humoral immunity, which affects susceptible microbiota and the genetic background. An in-depth understanding of the role of pathogenic factors forms the basis for developing novel and individualized therapeutic targets that can improve disease management.

Protein Citrullination by Peptidyl Arginine Deiminase/Arginine Deiminase Homologs in Members of the Human Microbiota and Its Recognition by Anti-Citrullinated Protein Antibodies

The human microbiome exists throughout the body, and it is essential for maintaining various physiological processes, including immunity, and dysbiotic events, which are associated with autoimmunity. Peptidylarginine deiminase (PAD) enzymes can citrullinate self-proteins related to rheumatoid arthritis (RA) that induce the production of anti-citrullinated protein antibodies (ACPAs) and lead to inflammation and joint damage. The present investigation was carried out to demonstrate the expression of homologs of PADs or arginine deiminases (ADs) and citrullinated proteins in members of the human microbiota. To achieve the objective, we used 17 microbial strains and specific polyclonal antibodies (pAbs) of the synthetic peptide derived from residues 100-200 of human PAD2 (anti-PAD2 pAb), and the recombinant fragment of amino acids 326 and 611 of human PAD4 (anti-PAD4 pAb), a human anti-citrulline pAb, and affinity ACPAs of an RA patient. Western blot (WB), enzyme-linked immunosorbent assay (ELISA), elution, and a test with Griess reagent were used. This is a cross-sectional case-control study on patients diagnosed with RA and control subjects. Inferential statistics were applied using the non-parametric Kruskal-Wallis test and Mann-Whitney U test generated in the SPSS program. Some members of phyla Firmicutes and Proteobacteria harbor homologs of PADs/ADs and citrullinated antigens that are reactive to the ACPAs of RA patients. Microbial citrullinome and homolog enzymes of PADs/ADs are extensive in the human microbiome and are involved in the production of ACPAs. Our findings suggest a molecular link between microorganisms of a dysbiotic microbiota and RA pathogenesis.

Distinct oral DNA viral signatures in rheumatoid arthritis: a Pilot study

Background

Despite evidence linking viruses and oral microbiome to rheumatoid arthritis (RA), limited whole genome sequencing research has been conducted on the oral virome (a viral component of the microbiome) of untreated RA patients. This pilot research seeks to address this knowledge gap by comparing the oral virome of untreated rheumatoid arthritis patients (RAs) and healthy individuals (HCs).

Method

Whole genome DNA sequence of saliva samples from 45 participants including 21 RAs and 24 age and gender matched HCs was obtained from the BioProject: PRJEB6997. Metaphlan3 pipeline and LEfSe analysis were used for the viral signature detection. Wilcoxon pairwise test and ROC analysis were used to validate and predict signatures.

Results

RA exhibits higher alpha diversity compared to HCs. Callitrichine gammaherpesvirus 3, Human gammaherpesvirus 4 (EBV), Murid betaherpesvirus 8, and Suid alphaherpesvirus 1 were enriched in RAs, while Aotine betaherpesvirus 1 from the Cytomegalovirus genus was enriched in HCs. In addition, Saccharomyces cerevisiae killer virus M1 (ScV-M1) was found to be enriched in RAs, whereas bacteriophage Hk97virus (Siphoviridae) and Cd119virus (Myoviridae) were enriched in HCs.

Conclusion

This study identifies significant DNA oral viral signatures at species level as potential biomarkers for the early detection and diagnosis of rheumatoid arthritis.