Diet, Microbiota, and Gut Permeability-The Unknown Triad in Rheumatoid Arthritis

G protein-coupled receptors related to autoimmunity in postural orthostatic tachycardia syndrome

Postural orthostatic tachycardia syndrome (POTS) is characterized by exaggerated orthostatic tachycardia in the absence of orthostatic hypotension. The pathophysiology of POTS may involve hypovolemia, autonomic neuropathy, a hyperadrenergic state, and cardiovascular deconditioning, any of which can co-occur in the same patient. Furthermore, there is growing evidence of the role of autoimmunity in a subset of POTS cases. In recent years, investigators have described an increased rate of autoimmune comorbidities as evidenced by the finding of several types of neural receptor autoantibody and non-specific autoimmune marker in patients with POTS. In particular, the association of the disease with several types of anti-G protein-coupled receptor (GPCR) antibodies and POTS has frequently been noted. A previous study reported that autoantibodies to muscarinic AChRs may play an important role in POTS with persistent, gastrointestinal symptoms. To date, POTS is recognized as one of the sequelae of coronavirus disease 2019 (COVID-19) and its frequency and pathogenesis are still largely unknown. Multiple autoantibody types occur in COVID-related, autonomic disorders, suggesting the presence of autoimmune pathology in these disorders. Herein, we review the association of anti-GPCR autoantibodies with disorders of the autonomic nervous system, in particular POTS, and provide a new perspective for understanding POTS-related autoimmunity.

Emerging role of gut microbiota in autoimmune diseases

Accumulating studies have indicated that the gut microbiota plays a pivotal role in the onset of autoimmune diseases by engaging in complex interactions with the host. This review aims to provide a comprehensive overview of the existing literatures concerning the relationship between the gut microbiota and autoimmune diseases, shedding light on the complex interplay between the gut microbiota, the host and the immune system. Furthermore, we aim to summarize the impacts and potential mechanisms that underlie the interactions between the gut microbiota and the host in autoimmune diseases, primarily focusing on systemic lupus erythematosus, rheumatoid arthritis, Sjögren's syndrome, type 1 diabetes mellitus, ulcerative colitis and psoriasis. The present review will emphasize the clinical significance and potential applications of interventions based on the gut microbiota as innovative adjunctive therapies for autoimmune diseases.

Associations between rheumatoid arthritis and intestinal flora, with special emphasis on RA pathologic mechanisms to treatment strategies

BACKGROUND

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease that primarily affects the joints. Individuals at risk for RA and people with RA develop intestinal dysbiosis. The changes in intestinal flora composition in preclinical and confirmed RA patients suggest that intestinal flora imbalance may play an important role in the induction and persistence of RA.

METHODS

Based on the current research on the interaction between RA and intestinal microbiota, intestinal microbiota metabolites and intestinal barrier changes. This paper systematically summarized the changes in intestinal microbiota in RA patients, the metabolites of intestinal flora, and the influence mechanism of intestinal barrier on RA, and further discussed the influence of drugs for RA on intestinal flora and its mechanism of action.

RESULTS

Compared with healthy controls, α diversity analysis of intestinal flora showed no significant difference, β diversity analysis showed significant differences. The intestinal flora produces bioactive metabolites, such as short-chain fatty acids and aromatic amino acids, which have anti-inflammatory effects. Abnormal intestinal flora leads to impaired barrier function and mucosal immune dysfunction, promoting the development of inflammation. Traditional Chinese medicine (TCM) and chemical drugs can also alleviate RA by regulating intestinal flora, intestinal flora metabolites, and intestinal barrier. Intestinal flora is closely related to the pathogenesis of RA and may become potential biomarkers for the diagnosis and treatment of RA.

CONCLUSIONS

Intestinal flora and its metabolites play an important role in the pathogenesis of autoimmune diseases such as RA, and are expected to become a new target for clinical diagnosis and treatment, providing a new idea for targeted treatment of RA.

The Role of the Gut Microbiome and Microbial Dysbiosis in Common Skin Diseases

Dermatoses are an increasingly common problem, particularly in developed countries. The causes of this phenomenon include genetic factors and environmental elements. More and more scientific reports suggest that the gut microbiome, more specifically its dysbiosis, also plays an important role in the induction and progression of diseases, including dermatological diseases. The gut microbiome is recognised as the largest endocrine organ, and has a key function in maintaining human homeostasis. In this review, the authors will take a close look at the link between the gut-skin axis and the pathogenesis of dermatoses such as atopic dermatitis, psoriasis, alopecia areata, and acne. The authors will also focus on the role of probiotics in remodelling the microbiome and the alleviation of dermatoses.

Microbial Imbalance and Intestinal Permeability in the Pathogenesis of Rheumatoid Arthritis: A Mechanism Review with a Focus on Bacterial Translocation, Citrullination, and Probiotic Intervention

This review aims to investigate the role of intestinal permeability (IP) in rheumatoid arthritis (RA), following the hypotheses that leakage of intestinal microbes can influence increased citrullination of peptides leading to anti-citrullinated protein antibody (ACPA) production and inflammation in RA; and that leaked microbes can migrate to the peripheral joints, leading to immune responses and synovitis in peripheral joints. This review explored the evidence for the link between microbial dysbiosis and increased IP in the inflammatory state in RA, as well as the role of increased citrullination and bacterial translocation in the link between microbiota and immune responses in RA. Furthermore, this research aims to evaluate the potential effect of probiotics on RA symptoms and pathogenesis via proposed mechanisms, including the support of microbial balance and suppression of inflammatory factors in RA. A systematic literature search was conducted in three tranches (review, mechanism, intervention). 71 peer-reviewed papers met the inclusions criteria and are summarized in a narrative analysis. Primary studies were critically appraised, synthesized and their relevance to clinical practice evaluated. Evidence found in this mechanism review consistently supported intestinal dysbiosis and increased IP in arthritis. An altered intestinal microbiome was demonstrated in RA with specific microbes such as Collinsella and Eggerthella correlating with increased IP, mucosal inflammation, and immune responses. Hypercitrullination and ACPA production correlated with arthritic symptoms and intestinal microbes were shown to influence hypercitrullination. Some in vitro and animal studies demonstrated a link between leakage of microbes and bacterial translocation, but further research is needed to elucidate the link between IP and citrullination. Probiotic intervention studies evidenced reductions in inflammatory markers IL-6 and TNFα, associated with proliferation of synovial tissue and pain perception in RA joint inflammation. Despite some conflict in the literature, probiotics may present a promising nutritional intervention in the suppression of both, disease activity and inflammatory markers.Key teaching pointsThere is evidence for a dysbiotic profile of the RA gut with specific RA-associated microbes.Increased intestinal permeability and leakage of PAD enzyme facilitates citrullination of peptides.Hypercitrullination and ACPA production correlate to arthritic signs.Microbial leakage and translocation plays a role in the pathogenesis of RA.Probiotics (e.g. L. Casei 01) may reduce inflammation and ameliorate RA symptoms.

Therapeutic effects of curcumin on constipation-predominant irritable bowel syndrome is associated with modulating gut microbiota and neurotransmitters

Introduction

Constipation-predominant irritable bowel syndrome (IBS-C) is a functional bowel disease that affects 10-20% of the population worldwide. Curcumin (CUR) is widely used in traditional Chinese medicine to treat IBS, but its mechanism of action needs further investigation.

Methods

In this study, we used mosapride (MOS) as a positive control to evaluate the changes in gut microbiota in IBS-C rat models after treatment with CUR or MOS by analyzing 16S rDNA variation. In addition, we used enzyme immunoassay kits and immunohistochemical analysis to investigate whether CUR or MOS influenced serotonin (5-HT), substance P (SP), and vasoactive intestinal peptide (VIP) levels in the serum and colon of IBS-C rats.

Results

The study showed that rats supplemented with CUR showed significantly increased fecal weight, fecal water content, small intestine transit rate and significantly decreased serum levels of 5-HT, VIP and SP compared to the IBS group (p < 0.05). In addition, treatment with CUR changed the relative abundance of Blautia, Sutterella, Acetanaerobacterium and Ruminococcus2 in the gut microbiota.

Discussion

This study showed that the efficacy of CUR on IBS-C was possibly by modulating the microbiota and lowering the serum levels of HT, SP, and VIP.

Circulating microbial cell-free DNA is increased during neutropenia after hematopoietic stem cell transplantation

We used a next-generation sequencing platform to characterize microbial cell-free DNA (mcfDNA) in plasma samples from patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HCT). In this observational study, we sought to characterize plasma mcfDNA in order to explore its potential association with the immunologic complications of transplantation. We compared serially collected patient samples with plasma collected from healthy control subjects. We observed changes in total mcfDNA burden in the plasma after transplantation, which was most striking during the early posttransplant neutropenic phase. This elevation could be attributed to a number of specific bacterial taxa, including Veillonella, Bacteroides, and Prevotella (genus level). For an additional cohort of patients, we compared the data of mcfDNA from plasma with 16s-ribosomal RNA sequencing data from stool samples collected at matched time points. In a number of patients, we confirmed that mcfDNA derived from specific microbial taxa (eg, Enterococcus) could also be observed in the matched stool sample. Quantification of mcfDNA may generate novel insights into mechanisms by which the intestinal microbiome influences systemic cell populations and, thus, has been associated with outcomes for patients with cancer.

Postbiotics in rheumatoid arthritis: emerging mechanisms and intervention perspectives

Rheumatoid arthritis (RA) is a prevalent chronic autoimmune disease that affects individuals of all age groups. Recently, the association between RA and the gut microbiome has led to the investigation of postbiotics as potential therapeutic strategies. Postbiotics refer to inactivated microbial cells, cellular components, or their metabolites that are specifically intended for the microbiota. Postbiotics not only profoundly influence the occurrence and development of RA, but they also mediate various inflammatory pathways, immune processes, and bone metabolism. Although they offer a variety of mechanisms and may even be superior to more conventional "biotics" such as probiotics and prebiotics, research on their efficacy and clinical significance in RA with disruptions to the intestinal microbiota remains limited. In this review, we provide an overview of the concept of postbiotics and summarize the current knowledge regarding postbiotics and their potential use in RA therapy. Postbiotics show potential as a viable adjunctive therapy option for RA.

Dysbiosis and Alzheimer's disease: role of probiotics, prebiotics and synbiotics

Alzheimer's disease (AD) is a neurodegenerative disease characterized by dementia and the accumulation of amyloid beta in the brain. Recently, microbial dysbiosis has been identified as one of the major factors involved in the onset and progression of AD. Imbalance in gut microbiota is known to affect central nervous system (CNS) functions through the gut-brain axis and involves inflammatory, immune, neuroendocrine and metabolic pathways. An altered gut microbiome is known to affect the gut and BBB permeability, resulting in imbalance in levels of neurotransmitters and neuroactive peptides/factors. Restoration of levels of beneficial microorganisms in the gut has demonstrated promising effects in AD in pre-clinical and clinical studies. The current review enlists the important beneficial microbial species present in the gut, the effect of their metabolites on CNS, mechanisms involved in dysbiosis related to AD and the beneficial effects of probiotics on AD. It also highlights challenges involved in large-scale manufacturing and quality control of probiotic formulations.

Small intestinal bacterial overgrowth: current update

PURPOSE OF REVIEW

This article aims to provide an up-to-date review of small intestinal bacterial overgrowth (SIBO), including etiology and risk factors, clinical manifestations, diagnostic evaluation for suspected SIBO, and therapeutic options.

RECENT FINDINGS

Recent advances in breath testing, capsule and urine-based testing have opened new avenues and improved diagnostic yield of SIBO. Nonantibiotic-based treatment strategies have shown promising results in initial trials.

SUMMARY

Small intestinal bacterial overgrowth (SIBO) is a condition defined by the excess bacteria or changes in bacterial composition of the small intestine. These are associated with various gastrointestinal (GI) symptoms such as bloating, abdominal distension, diarrhea, nutrient deficiencies, and even frank weight loss. Small bowel jejunal aspirate of >10 5 CFU/ml has traditionally been considered the gold standard for diagnosis. Glucose and lactulose breath testing have become more common in clinical practice as they are noninvasive, easily accessible, and have lower cost. Treatment focuses on the eradication of excess bacteria in the small bowel and is traditionally done with the use of oral antibiotics. Other emerging therapies may include probiotics, diet manipulation, and prokinetic agents.

Dietary Isoquercetin Ameliorates Bone Loss via Restoration of the Gut Microbiota and Lipopolysaccharide-Triggered Inflammatory Status in Ovariectomy Mice

Osteoporosis is one of the skeletal degenerative diseases accompanied by bone loss and microstructure disruption. Given that the gut-bone signaling axis highly contributes to bone health, here, dietary isoquercetin (IQ) was shown to effectively improve postmenopausal osteoporosis (PMO) in an ovariectomy (OVX) mouse model through the modulation of the gut-bone cross-talk. An in vivo study showed that OVX induced striking disruption of the microbial community, subsequently causing gut leakage and gut barrier dysfunction. As a result, lipopolysaccharide (LPS)-triggered inflammatory cytokines released from the intestine to bone marrow were determined to be associated with bone loss in OVX mice. Long-term dietary IQ effectively improved microbial community and gut barrier function in the OVX mice and thus markedly improved bone loss and host inflammatory status by repressing the NF-κB signaling pathway. An in vitro study further revealed that IQ treatments dose-dependently inhibited LPS-induced inflammation and partly promoted the proliferation and differentiation of osteoblasts. These results provide new evidence that dietary IQ has the potential for osteoporosis treatment.

The Mediterranean diet, and not dietary inflammatory index, is associated with rheumatoid arthritis disease activity, the impact of disease and functional disability

PURPOSE

To assess the relationship between adherence to the Mediterranean Diet (MD) /individual Dietary Inflammatory Index (DII) and disease activity, disease impact, and functional status in Rheumatoid Arthritis (RA) patients.

METHODS

RA patients followed at a hospital in Lisbon, Portugal, were recruited. DII was calculated using dietary intake data collected with a food frequency questionnaire (FFQ). Adherence to the MD was obtained using the 14-item Mediterranean Diet assessment tool. Disease Activity Score of 28 Joints (DAS28) and the DAS28 calculated with C-Reactive Protein (DAS28-CRP) were used to assess disease activity. Impact of disease and functional status were evaluated using the Rheumatoid Arthritis Impact of Disease (RAID) questionnaire and the Health Assessment Questionnaire (HAQ), respectively.

RESULTS

120 patients (73.3% female, 61.8 ± 10.1 years of age) were included. Patients with higher adherence to the MD had significantly lower DAS28-CRP (median 3.27(2.37) vs 2.77(1.49), p = 0.030), RAID (median 5.65(2.38) vs 3.51(4.51), p = 0.032) and HAQ (median 1.00(0.56) vs 0.56(1.03), p = 0.013) scores. Higher adherence to the MD reduced the odds of having a higher DAS28 by 70% (OR = 0.303, 95%CI = (0.261, 0.347), p = 0.003). Lower adherence to MD was associated with higher DAS28-CRP (β = - 0.164, p = 0.001), higher RAID (β = - 0.311, p < 0.0001), and higher HAQ scores (β = - 0.089, p = 0.001), irrespective of age, gender, BMI and pharmacological therapy. Mean DII of our cohort was not significantly different from the Portuguese population (0.00 ± 0.17 vs - 0.10 ± 1.46, p = 0.578). No associations between macronutrient intake or DII and RA outcomes were found.

CONCLUSIONS

Higher adherence to the MD was associated with lower disease activity, lower impact of disease, and lower functional disability in RA patients.

NAD+ Precursors and Intestinal Inflammation: Therapeutic Insights Involving Gut Microbiota

The oxidized form of nicotinamide adenine dinucleotide (NAD+) is a critical metabolite for living cells. NAD+ may act either as a cofactor for many cellular reactions as well as a coenzyme for different NAD+-consuming enzymes involved in the physiological homeostasis of different organs and systems. In mammals, NAD+ is synthesized from either tryptophan or other vitamin B3 intermediates that act as NAD+ precursors. Recent research suggests that NAD+ precursors play a crucial role in maintaining the integrity of the gut barrier. Indeed, its deficiency has been associated with enhanced gut inflammation and leakage, and dysbiosis. Conversely, NAD+-increasing therapies may confer protection against intestinal inflammation in experimental conditions and human patients, with accumulating evidence indicating that such favorable effects could be, at least in part, mediated by concomitant changes in the composition of intestinal microbiota. However, the mechanisms by which NAD+-based treatments affect the microbiota are still poorly understood. In this context, we have focused specifically on the impact of NAD+ deficiency on intestinal inflammation and dysbiosis in animal and human models. We have further explored the relationship between NAD+ and improved host intestinal metabolism and immunity and the composition of microbiota in vivo. Overall, this comprehensive review aims to provide a new perspective on the effect of NAD+-increasing strategies on host intestinal physiology.

Beyond Seasoning-The Role of Herbs and Spices in Rheumatic Diseases

Although we have witnessed remarkable progress in understanding the biological mechanisms that lead to the development of rheumatic diseases (RDs), remission is still not achieved in a substantial proportion of patients with the available pharmacological treatment. As a consequence, patients are increasingly looking for complementary adjuvant therapies, including dietary interventions. Herbs and spices have a long historical use, across various cultures worldwide, for both culinary and medicinal purposes. The interest in herbs and spices, beyond their seasoning properties, has dramatically grown in many immune-mediated diseases, including in RDs. Increasing evidence highlights their richness in bioactive molecules, such as sulfur-containing compounds, tannins, alkaloids, phenolic diterpenes, and vitamins, as well as their antioxidant, anti-inflammatory, antitumorigenic, and anticarcinogenic properties. Cinnamon, garlic, ginger, turmeric, and saffron are the most popular spices used in RDs and will be explored throughout this manuscript. With this paper, we intend to provide an updated review of the mechanisms whereby herbs and spices may be of interest in RDs, including through gut microbiota modulation, as well as summarize human studies investigating their effects in Rheumatoid Arthritis, Osteoarthritis, and Fibromyalgia.

Assessment of Intestinal Permeability and Inflammation Bio-Markers in Patients with Rheumatoid Arthritis

Increased intestinal permeability and inflammation, both fueled by dysbiosis, appear to contribute to rheumatoid arthritis (RA) pathogenesis. This single-center pilot study aimed to investigate zonulin, a marker of intestinal permeability, and calprotectin, a marker of intestinal inflammation, measured in serum and fecal samples of RA patients using commercially available kits. We also analyzed plasma lipopolysaccharide (LPS) levels, a marker of intestinal permeability and inflammation. Furthermore, univariate, and multivariate regression analyses were carried out to determine whether or not there were associations of zonulin and calprotectin with LPS, BMI, gender, age, RA-specific parameters, fiber intake, and short-chain fatty acids in the gut. Serum zonulin levels were more likely to be abnormal with a longer disease duration and fecal zonulin levels were inversely associated with age. A strong association between fecal and serum calprotectin and between fecal calprotectin and LPS were found in males, but not in females, independent of other biomarkers, suggesting that fecal calprotectin may be a more specific biomarker than serum calprotectin is of intestinal inflammation in RA. Since this was a proof-of-principle study without a healthy control group, further research is needed to validate fecal and serum zonulin as valid biomarkers of RA in comparison with other promising biomarkers.

Serum Levels of IFABP2 and Differences in Lactobacillus and Porphyromonas gingivalis Abundance on Gut Microbiota Are Associated with Poor Therapeutic Response in Rheumatoid Arthritis: A Pilot Study

Intestinal dysbiosis is related to the physiopathology and clinical manifestation of rheumatoid arthritis (RA) and the response to pharmacologic treatment. The objectives of this study were (1) to analyze the effect of conventional synthetic disease modifying anti-rheumatic drugs (csDMARDs) on the abundance of gut microbiota's bacteria; (2) to evaluate the relationship between the differences in microbial abundance with the serum levels of intestinal fatty-acid binding protein 2 (IFABP2), cytokines, and the response phenotype to csDMARDs therapy in RA. A cross-sectional study was conducted on 23 women diagnosed with RA. The abundance of bacteria in gut microbiota was determined with qPCR. The ELISA technique determined serum levels of IFABP2, TNF-α, IL-10, and IL-17A. We found that the accumulated dose of methotrexate or prednisone is negatively associated with the abundance of Lactobacillus but positively associated with the abundance of Bacteroides fragilis. The Lactobacillus/Porphyromonas gingivalis ratio was associated with the Disease Activity Score-28 for RA with Erythrocyte Sedimentation Rate (DAS28-ESR) (r = 0.778, p = 0.030) and with the levels of IL-17A (r = 0.785, p = 0.027) in the group treated with csDMARD. Moreover, a relation between the serum levels of IFABP2 and TNF-α (r = 0.593, p = 0.035) was observed in the group treated with csDMARD. The serum levels of IFABP2 were higher in patients with secondary non-response to csDMARDs therapy. In conclusion, our results suggest that the ratios of gut microbiota's bacteria and intestinal permeability seems to establish the preamble for therapeutic secondary non-response in RA.

Immune Responses at Host Barriers and Their Importance in Systemic Autoimmune Diseases

Host barriers such as the skin, the lung mucosa, the intestinal mucosa and the oral cavity are crucial at preventing contact with potential threats and are populated by a diverse population of innate and adaptive immune cells. Alterations in antigen recognition driven by genetic and environmental factors can lead to autoimmune systemic diseases such rheumatoid arthritis, systemic lupus erythematosus and food allergy. Here we review how different immune cells residing at epithelial barriers, host-derived signals and environmental signals are involved in the initiation and progression of autoimmune responses in these diseases. We discuss how regulation of innate responses at these barriers and the influence of environmental factors such as the microbiota can affect the susceptibility to develop local and systemic autoimmune responses particularly in the cases of food allergy, systemic lupus erythematosus and rheumatoid arthritis. Induction of pathogenic autoreactive immune responses at host barriers in these diseases can contribute to the initiation and progression of their pathogenesis.

Crosstalk between Resveratrol and Gut Barrier: A Review

The plant-based nutraceuticals are receiving increasing interest in recent time. The high attraction to the phytochemicals is associated with their anti-inflammatory and antioxidant activities, which can lead to reduced risk of the development of cardiovascular and other non-communicable diseases. One of the most disseminated groups of plant bioactives are phenolic compounds. It was recently hypothesized that phenolic compounds can have the ability to improve the functioning of the gut barrier. The available studies showed that one of the polyphenols, resveratrol, has great potential to improve the integrity of the gut barrier. Very promising results have been obtained with in vitro and animal models. Still, more clinical trials must be performed to evaluate the effect of resveratrol on the gut barrier, especially in individuals with increased intestinal permeability. Moreover, the interplay between phenolic compounds, intestinal microbiota and gut barrier should be carefully evaluated in the future. Therefore, this review offers an overview of the current knowledge about the interaction between polyphenols with a special emphasis on resveratrol and the gut barrier, summarizes the available methods to evaluate the intestinal permeability, discusses the current research gaps and proposes the directions for future studies in this research area.

A high-fiber diet synergizes with Prevotella copri and exacerbates rheumatoid arthritis

Both preclinical and established rheumatoid arthritis (RA) patients display alterations in the gut microbiome. Prevotella spp. are preferentially enriched in a subset of RA patients. Here, we isolated a Prevotella strain, P. copri RA, from the feces of RA patients and showed that colonization of P. copri RA exacerbated arthritis in a collagen-induced arthritis (CIA) model. With the presence of P. copri RA colonization, a high-fiber diet exacerbated arthritis via microbial alterations and intestinal inflammation. Colonization of P. copri together with a high-fiber diet enabled the digestion of complex fiber, which led to the overproduction of organic acids, including fumarate, succinate and short-chain fatty acids. Succinate promoted proinflammatory responses in macrophages, and supplementation with succinate exacerbated arthritis in the CIA model. Our findings highlight the importance of dysbiosis when evaluating the effects of dietary interventions on RA pathogenesis and provide new insight into dietary interventions or microbiome modifications to improve RA management.

Contribution of HLA DRB1, PTPN22, and CTLA4, to RA dysbiosis

This narrative review gathers current evidence for a contribution of rheumatoid arthritis (RA) HLA-DRB1, PTPN22 and CTLA4 polymorphisms to the gut dysbiosis observed in RA, especially at its onset (transient excess of Prevotella). The gut microbiome contains elements which are 30% heritable, including genera like Bacteroides and Veillonella, and to a lesser extent Prevotella. The first months/year seems a critical period for the selection of a core of microbiota, that should be considered as a second self by the immune system, and tolerized by regulatory T and B cells. Imperfect tolerization may increase the risk of RA following further repeated silent translocations of various gut microorganisms, including Prevotella copri, from gut to joints (fostered by a concurrent loss in gut mucosa of protective bacteria like Faecalibacterium prausnitzii). Genetics studies confirmed that Prevotella copri was partly heritable, and strong associations were observed between the overall microbial composition of stools and the HLA-DRB1 RA risk allele, either in a US cohort (P=0.00001), or the Twins UK cohort (P=0.033). This finding also stands for persons still free from RA, and was replicated in the Swiss SCREEN-RA cohort. Gene variants of PTPN22 also modify intestinal microbiota composition, compromise granulocyte-mediated antibacterial defence in gut, and reduce the suppressive effect of gut regulatory B cells. CTLA4 variants may similarly contribute to RA dysbiosis, since immunotherapy by CTLA-4 blockade depends on microbiota, and CTLA4 activates T follicular regulatory cells to reduce immune responses to segmented filamentous bacteria. Suggestions for future works are made.

Dysbiotic Oral and Gut Viromes in Untreated and Treated Rheumatoid Arthritis Patients

Rheumatoid arthritis (RA) is influenced by oral and gut bacteria; however, much less is known about the relationship between oral or gut viromes and RA. Here, we performed whole-oral- and whole-gut-virome analyses based on shotgun sequencing of 497 samples. A comparative analysis of the oral and gut viromes in healthy controls and untreated and treated RA patients was performed, and system interaction networks among viruses, bacteria, and RA-associated clinical indices were constructed to address the potential relationship between the virome and RA by principal-coordinate analysis, distance-based redundancy analysis, permutational multivariate analysis, Spearman correlation coefficient analysis, and random-forest model analysis. The results showed that the viromes could be profiled in dental plaque, saliva, and fecal samples, among which saliva had the highest within-sample diversity. Importantly, significantly different diversities and compositions of the oral (i.e., dental plaque and saliva) viromes were observed not only between RA patients and healthy controls but also between untreated and treated RA patients, yet there were relatively minor differences in the gut viromes. Furthermore, to understand how these viruses affected the bacteriome, a virus-bacterium interaction network was constructed from dental plaque, saliva, and fecal samples of RA patients. Additionally, some RA-associated oral taxa, including Lactococcus phage (vOTU70), Bacteroides vulgatus, Lactococcus lactis, Escherichia coli, and Neisseria elongata, were correlated with the RA-related clinical indices. Whole-virome analysis illustrated the potential role of the oral and gut viromes in affecting our body either directly or via bacteria, which characterized neglected and new candidates contributing to the development of RA. IMPORTANCE Our results demonstrated community variation among dental plaque, saliva, and fecal viromes. In oral and gut samples from untreated and treated RA patients, the perturbance of viral composition and the correlation network of microbes and RA-associated clinical indices might be involved in the pathogenicity of RA. The findings in this study expand the knowledge of the potential role of oral and gut viral communities in the development of RA and may contribute to research on correlations between viruses and other diseases.

Impact of fibre and red/processed meat intake on treatment outcomes among patients with chronic inflammatory diseases initiating biological therapy: A prospective cohort study

Background

Biologic disease-modifying drugs have revolutionised the treatment of a number of chronic inflammatory diseases (CID). However, up to 60% of the patients do not have a sufficient response to treatment and there is a need for optimization of treatment strategies.

Objective

To investigate if the treatment outcome of biological therapy is associated with the habitual dietary intake of fibre and red/processed meat in patients with a CID.

Methods

In this multicentre prospective cohort study, we consecutively enrolled 233 adult patients with a diagnosis of Crohn's Disease, Ulcerative Colitis, Rheumatoid Arthritis (RA), Axial Spondyloarthritis, Psoriatic Arthritis and Psoriasis, for whom biologic therapy was planned, over a 3 year period. Patients with completed baseline food frequency questionnaires were stratified into a high fibre/low red and processed meat exposed group (HFLM) and an unexposed group (low fibre/high red and processed meat intake = LFHM). The primary outcome was the proportion of patients with a clinical response to biologic therapy after 14-16 weeks of treatment.

Results

Of the 193 patients included in our primary analysis, 114 (59%) had a clinical response to biologic therapy. In the HFLM group (N = 64), 41 (64%) patients responded to treatment compared to 73 (56%) in the LFHM group (N = 129), but the difference was not statistically significant (OR: 1.48, 0.72-3.05). For RA patients however, HFLM diet was associated with a more likely clinical response (82% vs. 35%; OR: 9.84, 1.35-71.56).

Conclusion

Habitual HFLM intake did not affect the clinical response to biological treatment across CIDs. HFLM diet in RA patients might be associated with better odds for responding to biological treatment, but this would need confirmation in a randomised trial.

Trial registration

(clinicaltrials.gov), identifier [NCT03173144].

Targeting the Gut Microbiome for Inflammation and Pain Management in Orthopedic Conditions

The human gut microbiome can be altered with probiotics, prebiotics, synbiotics, and anti-inflammatory foods and spices as part of an evidence-based strategy that targets inflammation and pain in common orthopedic conditions. Implementing these strategies avoids adverse effects associated with nonsteroidal anti-inflammatory drugs and minimizes the potential for opioid use. This review focuses exclusively on human trials studying the effects of gut microbiome alterations to address pain and inflammatory markers in common orthopedic conditions: osteoarthritis, rheumatoid arthritis, fractures/osteoporosis, and bone pain associated with chemotherapy. Individualized supplementation strategies can be further explored with the information in this review. [Orthopedics. 2022;45(5):e226-e234.].

Non-pharmacological treatment in difficult-to-treat rheumatoid arthritis

Although the management of rheumatoid arthritis (RA) has improved remarkably with new pharmacological therapies, there is still a significant part of patients not reaching treatment goals. Difficult-to-treat RA (D2TRA) is a complex entity involving several factors apart from persistent inflammation, thereafter requiring a holistic management approach. As pharmacological treatment options are often limited in D2TRA, the need for non-pharmacological treatments (NPT) is even more pronounced. The mechanism of action of non-pharmacological treatments is not well investigated, NPTs seem to have a complex, holistic effect including the immune, neural and endocrine system, which can have a significant additive benefit together with targeted pharmacotherapies in the treatment of D2TRA. In this review we summarize the current knowledge on different NPT in rheumatoid arthritis, and we propose a NPT plan to follow when managing D2TRA patients.

Disease mechanisms in preclinical rheumatoid arthritis: A narrative review

In the last decades, the concept of preclinical rheumatoid arthritis (RA) has become established. In fact, the discovery that disease mechanisms start years before the onset of clinical RA has been one of the major recent insights in the understanding of RA pathogenesis. In accordance with the complex nature of the disease, preclinical events extend over several sequential phases. In a genetically predisposed host, environmental factors will further increase susceptibility for incident RA. In the initial steps of preclinical disease, immune disturbance mechanisms take place outside the joint compartment, namely in mucosal surfaces, such as the lung, gums or gut. Herein, the persistent immunologic response to altered antigens will lead to breach of tolerance and trigger autoimmunity. In a second phase, the immune response matures and is amplified at a systemic level, with epitope spreading and widening of the autoantibody repertoire. Finally, the synovial and bone compartment are targeted by specific autoantibodies against modified antigens, initiating a local inflammatory response that will eventually culminate in clinically evident synovitis. In this review, we discuss the elaborate disease mechanisms in place during preclinical RA, providing a broad perspective in the light of current evidence.

Colonic mucosal microbiota is associated with bowel habit subtype and abdominal pain in patients with irritable bowel syndrome

Mucosal microbiota differ significantly from fecal microbiota and may play a different role in the pathophysiology of irritable bowel syndrome (IBS). The aims of this study were to determine if the composition of mucosal microbiota differed between IBS, or IBS bowel habit (BH) subtypes, and healthy controls (HCs). Sigmoid colon mucosal biopsies were obtained from 97 Rome-positive patients with IBS (28% IBS-constipation, 38% IBS-diarrhea, 24% IBS-mixed, and 10% IBS-unsubtyped) and 54 HCs, from which DNA was extracted. 16S rRNA gene sequencing and microbial composition analysis were performed. Group differences in α and β diversity and taxonomic level differences were determined using linear regression while controlling for confounding variables. IBS BH subtype was associated with microbial α diversity (P = 0.0003) with significant differences seen in the mucosal microbiota of IBS-constipation versus IBS-diarrhea (P = 0.046). There were no significant differences in α or β diversity in the mucosal microbiota of IBS versus HCs (P = 0.29 and 0.93, respectively), but metagenomic profiling suggested functional differences. The relative abundance of Prevotella_9 copri within IBS was significantly correlated with increased abdominal pain (r = 0.36, P = 0.0003), which has not been previously reported in IBS. Significant differences in the mucosal microbiota were present within IBS BH subtypes but not between IBS and HCs, supporting the possibility of IBS BH subtype-specific pathogenesis. Increased Prevotella copri may contribute to symptoms in patients with IBS.NEW & NOTEWORTHY Gut mucosal microbiota differs significantly from fecal microbiota in irritable bowel syndrome (IBS) and may play a different role in its pathophysiology. Investigation of colonic mucosal microbiota in the largest cohort of patients with IBS and healthy controls accounting for confounding variables, including diet demonstrated significant differences in mucosal microbiota between IBS bowel habit subtypes but not between IBS and healthy controls. In addition, the study reported gut microbiota is associated with abdominal pain in patients with IBS.

Inadequate Dietary Nutrient Intake in Patients With Rheumatoid Arthritis in Southwestern Sweden: A Cross-Sectional Study

Background

Patients with rheumatoid arthritis (RA), who suffer from impaired physical function and fatigue, may have difficulties with grocery shopping and preparing meals. Also, to improve symptoms, patients often experiment with diets but seldom consult a dietitian. Although this could lead to a nutritiously deprived diet, an up-to-date, thorough description of the nutrient intake in Swedish patients with RA is absent. Here, we investigated the habitual dietary energy and nutrient intake in patients with RA living in southwestern Sweden.

Materials and Methods

Three-day food records performed at two time points during the ADIRA (Anti-inflammatory Diet In Rheumatoid Arthritis) trial, were used. The intake of energy and nutrients was analyzed using The Swedish Food Composition Database.

Results

A total of 62 participants (50 females, 12 males) were included in the study, where 18 participants completed one 3-day food record and 44 participants completed two 3-day food records. Median (IQR) intake of total fat was above or in the upper range of recommendations (females: 37.1 [32.5, 41.7] energy percent (E%), and males: 40.3 [37.5, 42.9] E%). Median (IQR) intake of saturated fatty acids exceeded recommendations (females: 14.9 [12.5, 17.0] E% and males: 15.4 [12.2, 17.0] E%), while median (IQR) carbohydrate and fiber intakes were below recommendations (females: 41.7 [36.3, 45.4] E% and 17.2 [12.8, 20.9] g, respectively, and males: 38.8 [35.2, 40,3] E% and 18.5 [15.7, 21.0] g, respectively). The reported intake of other macronutrients was in line with recommendations. For several micronutrients, e.g., vitamin A and D, folate, and calcium, median intake was below recommended intake. Vitamin A intake was especially low and did not reach lower intake level (LI) for 14 and 17% of females and males, respectively. For females, about 10% did not reach LI for vitamin D, calcium, and riboflavin.

Conclusion

We found that patients with RA residing in southwestern Sweden reported a high intake of saturated fatty acids and low intake of fiber and several micronutrients.

Clinical Trial Registration

[https://clinicaltrials.gov/ct2/show/NCT02941055?term=NCT02941055&amp;draw=2&amp;rank=1], identifier [NCT02941055].

Loss of Gut Barrier Integrity In Lupus

Systemic Lupus Erythematosus is a complex autoimmune disease and its etiology remains unknown. Increased gut permeability has been reported in lupus patients, yet whether it promotes or results from lupus progression is unclear. Recent studies indicate that an impaired intestinal barrier allows the translocation of bacteria and bacterial components into systemic organs, increasing immune cell activation and autoantibody generation. Indeed, induced gut leakage in a mouse model of lupus enhanced disease characteristics, including the production of anti-dsDNA antibody, serum IL-6 as well as cell apoptosis. Gut microbiota dysbiosis has been suggested to be one of the factors that decreases gut barrier integrity by outgrowing harmful bacteria and their products, or by perturbation of gut immune homeostasis, which in turn affects gut barrier integrity. The restoration of microbial balance eliminates gut leakage in mice, further confirming the role of microbiota in maintaining gut barrier integrity. In this review, we discuss recent advances on the association between microbiota dysbiosis and leaky gut, as well as their influences on the progression of lupus. The modifications on host microbiota and gut integrity may offer insights into the development of new lupus treatment.

Different Exercise Intensity Associates with Varied Disease Biomarkers of Guts-Microbiome Genera Change in Rats: Preliminary Study

The microbiome, a community of microorganisms in the body, is currently used as a biomarker in many disease prognoses. Prevotella, Turicibacte, Bacteroides, Firmicutes/Bacteroidetes are frequently used as a biomarker for rheumatoid arthritis, colorectal cancer, and obesity in ordered. The amount of gut microbiota can be changed depending on various factors such as diet, lifestyle, and exercise. However, there is unclear on how the exercise is really effective to be a disease prevention. The present study aims to investigate the different exercise intensities on gut microbiome abundance changes that could be used as a disease biomarker. Eighteen Sprague-Dawley rats were arranged (n=6 per group) into 3 exercise intensity levels on treadmills including non-exercise group, high -exercise group (20 – 25 m/min for 60 min), and light-exercise group (10 – 15 m/min for 60 min). Rats were weighted every 2 days and stools were collected and preserved in DNA/RNA shield each week. The bacterial 16S rDNA of microbiome in feces samples was sequenced and analyzed. After week eighth of the interventions, from operational taxonomic unit (OTUs) abundance, we found that the relative abundance in bacterial genera in Prevotella and Firmicutes/Bacteroidetes were significantly correlated with the experiment timepoints in different exercise intensities (Pearson’s correlation, P<0.05) compare to other genera. The exercise intensities and exercise durations can affect the relative abundance in the bacteria genus which the abundance genus Prevotella and Firmicutes/Bacteroidetes could be used as a new standard biomarker in exercise as a disease prevention and exercise prescriptions. From the funding limitations, we could conclude the research results based on our data and statistic. Future research should utilize a longer investigation period.

Gut–Skin Axis: Unravelling the Connection between the Gut Microbiome and Psoriasis

Evidence has shown that gut microbiome plays a role in modulating the development of diseases beyond the gastrointestinal tract, including skin disorders such as psoriasis. The gut–skin axis refers to the bidirectional relationship between the gut microbiome and skin health. This is regulated through several mechanisms such as inflammatory mediators and the immune system. Dysregulation of microbiota has been seen in numerous inflammatory skin conditions such as atopic dermatitis, rosacea, and psoriasis. Understanding how gut microbiome are involved in regulating skin health may lead to development of novel therapies for these skin disorders through microbiome modulation, in particularly psoriasis. In this review, we will compare the microbiota between psoriasis patients and healthy control, explain the concept of gut–skin axis and the effects of gut dysbiosis on skin physiology. We will also review the current evidence on modulating gut microbiome using probiotics in psoriasis.

Relationship between Gut Microbiota and Bone Health

Gut microbiota (GM) are microorganisms that live in the host gastrointestinal tract, and their abundance varies throughout the host's life. With the development of sequencing technology, the role of GM in various diseases has been increasingly elucidated. Unlike earlier studies on orthopedic diseases, this review elucidates the correlation between GM health and bone health, and discusses the potential mechanism of GM effects on host metabolism, inflammation, and ability to induce or aggravate some common orthopedic diseases such as osteoarthritis, osteoporosis, rheumatoid arthritis, etc. Finally, the prospective methods of GM manipulation and evaluation of potential GM-targeting strategies in the diagnosis and treatment of orthopedic diseases are reviewed.

Traditional Tibetan Medicine Twenty-Five Wei’er Tea Pills Ameliorate Rheumatoid Arthritis Based on Chemical Crosstalk Between Gut Microbiota and the Host

Twenty-Five Wei’er Tea Pills (TFP), a traditional Tibetan medicine, has shown to have a promising therapeutic effect in patients with Rheumatoid arthritis (RA), as well as being safe. Nonetheless, there have been limited pharmacological studies that have explored this therapeutic option. As gut microbiota has been proven to have a critical role in the pathogenesis of RA, this study aims to explore and reveal relevant ways by which TFP interacts with the chemical crosstalk between the gut microbiome and its host. 16S rRNA sequencing, combined with un-targeted metabolomics, were conducted on collagen-induced arthritis (CIA) rats. CIA model rats treated with TFP showed significant improvement in weight gain, pathological phenomena in joints, as well as decreased serum levels of TNF-α, IL-6 and increased level of IL-4 and IL-10. Significant dysfunction in the gut microbiome and alteration in serum metabolites were observed in CIA model rats, which were restored by TFP treatment. Coherence analysis indicated that TFP modulated the pathways of histidine metabolism, phenylalanine metabolism, alanine, aspartate, glutamate metabolism, amino sugar and nucleotide sugar metabolism owing to the abundances of Lactobacillus, Bacteroides, Prevotellaceae_UCG-001 and Christensenellaceae_R-7_group in the gut microflora. The corresponding metabolites involved L-histidine, histamine, phenylethylamine, asparagine, L-aspartic acid, D-fructose 1-phosphate, D-Mannose 6-phosphate, D-Glucose 6-phosphate, and Glucose 1-phosphate. In conclusion, this study reveals the ameliorative effects of TFP on RA through the chemical crosstalk that exists between the gut microbiota and its host, and also further enriches our understandings of the pathogenesis of RA.

Association of autoantibodies to muscarinic acetylcholine receptors with gastrointestinal symptoms and disease severity in patients with postural orthostatic tachycardia syndrome

Previous studies have reported a relationship between postural orthostatic tachycardia syndrome (POTS) and positivity for serum autoantibodies against G-protein-coupled receptors (GPCRs). However, the role of these autoantibodies in POTS is unclear. The present retrospective study analyzed the autoimmune etiology of POTS in 24 patients using a head-up tilt test to assess for any correlation between the clinical features of POTS and serum levels of autoantibodies against diverse GPCRs. In total, ten assessment items, including autonomic function tests, were analyzed. Of these, persistent, gastrointestinal symptoms and disease severity showed a significant association with the serum level of anti-muscarinic acetylcholine receptor (mAChRs) antibodies (gastrointestinal symptoms, M1, M2, M5; disease severity, M1, M3, M4, M5) [P <0.05]), while no significant association was found between the clinical features and autoantibodies against adrenergic receptors (α1, α2, β1, β2), angiotensin receptor 1, or endothelin receptor A. The patients were further divided into two groups based on the presence or absence of persistent gastrointestinal symptoms and then were characterized by the ten assessment items and neuropsychological tests, including the Wechsler Adult Intelligence Scale score and Self-Rating Depression Scale score. The results demonstrated a clear difference between the two groups in terms of disease severity, age at onset (older or younger than 20 years), and processing speed index (P <0.05), which were highly consistent with the association between these clinical features and the levels of serum anti-mAChR antibodies, particularly the anti-M5 receptor antibody. These findings suggested that anti-mAChR antibodies may play an important role in a subgroup of POTS patients with persistent gastrointestinal symptoms.

Etiology and Risk Factors for Rheumatoid Arthritis: A State-of-the-Art Review

Rheumatoid arthritis (RA) is the most common systemic inflammatory rheumatic disease. It is associated with significant burden at the patient and societal level. Extensive efforts have been devoted to identifying a potential cause for the development of RA. Epidemiological studies have thoroughly investigated the association of several factors with the risk and course of RA. Although a precise etiology remains elusive, the current understanding is that RA is a multifactorial disease, wherein complex interactions between host and environmental factors determine the overall risk of disease susceptibility, persistence and severity. Risk factors related to the host that have been associated with RA development may be divided into genetic; epigenetic; hormonal, reproductive and neuroendocrine; and comorbid host factors. In turn, environmental risk factors include smoking and other airborne exposures; microbiota and infectious agents; diet; and socioeconomic factors. In the present narrative review, aimed at clinicians and researchers in the field of RA, we provide a state-of-the-art overview of the current knowledge on this topic, focusing on recent progresses that have improved our comprehension of disease risk and development.

Higher bacterial DNAemia can affect the impact of a polyphenol-rich dietary pattern on biomarkers of intestinal permeability and cardiovascular risk in older subjects

PURPOSE

Aging can be characterized by increased systemic low-grade inflammation, altered gut microbiota composition, and increased intestinal permeability (IP). The intake of polyphenol-rich foods is proposed as a promising strategy to positively affect the gut microbiota-immune system-intestinal barrier (IB) axis. In this context, we tested the hypothesis that a PR-dietary intervention would affect the presence of bacterial factors in the bloodstream of older adults.

METHODS

We collected blood samples within a randomized, controlled, crossover intervention trial in which older volunteers (n = 51) received a polyphenol-enriched and a control diet. We quantified the presence of bacterial DNA in blood by qPCR targeting the 16S rRNA gene (16S; bacterial DNAemia). Blood DNA was taxonomically profiled via 16S sequencing.

RESULTS

Higher blood 16S levels were associated with higher BMI and markers of IP, inflammation, and dyslipidemia. PR-intervention did not significantly change bacterial DNAemia in the older population (P = 0.103). Nonetheless, the beneficial changes caused by the polyphenol-enriched diet were greatest in participants with higher bacterial DNAemia, specifically in markers related to IP, inflammation and dyslipidemia, and in fecal bacterial taxa. Finally, we found that the bacterial DNA detected in blood mostly belonged to γ-Proteobacteria, whose abundance significantly decreased after the polyphenol-rich diet in subjects with higher bacterial DNAemia at baseline.

CONCLUSIONS

This study shows that older subjects with higher bacterial DNAemia experienced a beneficial effect from a polyphenol-rich diet. Bacterial DNAemia may be a further relevant marker for the identification of target populations that could benefit more from a protective dietary treatment.

REGISTRATION

This trial was retrospectively registered at www.isrctn.org (ISRCTN10214981) on April 28, 2017.

Altered Intestinal Permeability and Drug Repositioning in a Post-operative Ileus Guinea Pig Model

Background/Aims

The aim of this study is to identify the alteration in intestinal permeability with regard to the development of post-operative ileus (POI). Moreover, we investigated drug repositioning in the treatment of POI.

Methods

An experimental POI model was developed using guinea pigs. To measure intestinal permeability, harvested intestinal membranes of the ileum and proximal colon was used in an Ussing chamber. To identify the mechanisms associated with altered permeability, we measured leukocyte count and expression of calprotectin, claudin-1, claudin-2, and mast cell tryptase. We compared control, POI, and drug groups (mosapride [0.3 mg/kg and 1 mg/kg, orally], glutamine [500 mg/kg, orally], or ketotifen [1 mg/kg, orally] with regard to these parameters.

Results

Increased permeability after surgery significantly decreased after administration of mosapride, glutamine, or ketotifen. Leukocyte counts increased in the POI group and decreased significantly after administration of mosapride (0.3 mg/kg) in the ileum, and mosapride (0.3 mg/kg and 1 mg/kg), glutamine, or ketotifen in the proximal colon. Increased expression of calprotectin after surgery decreased after administration of mosapride (0.3 mg/kg), glutamine, or ketotifen in the ileum and proximal colon, and mosapride (1 mg/kg) in the ileum. The expression of claudin-1 decreased significantly and that of claudin-2 increased after operation. After administration of glutamine, the expression of both proteins was restored. Finally, mast cell tryptase levels increased in the POI group and decreased significantly after administration of ketotifen.

Conclusions

The alteration in intestinal permeability is one of the factors involved in the pathogenesis of POI. We repositioned 3 drugs (mosapride, glutamine, and ketotifen) as novel therapeutic agents for POI.

Extracellular Vesicles in Human Milk

Milk supports the growth and development of infants. An increasing number of mostly recent studies have demonstrated that milk contains a hitherto undescribed component called extracellular vesicles (EVs). This presents questions regarding why milk contains EVs and what their function is. Recently, we showed that EVs in human milk expose tissue factor, the protein that triggers coagulation or blood clotting, and that milk-derived EVs promote coagulation. Because bovine milk, which also contains EVs, completely lacks this coagulant activity, important differences are present in the biological functions of human milk-derived EVs between species. In this review, we will summarize the current knowledge regarding the presence and biochemical composition of milk EVs, their function(s) and potential clinical applications such as in probiotics, and the unique problems that milk EVs encounter in vivo, including survival of the gastrointestinal conditions encountered in the newborn. The main focus of this review will be human milk-derived EVs, but when available, we will also include information regarding non-human milk for comparison.

Can Studying Genetically Predisposed Individuals Inform Prevention Strategies for RA?

Rheumatoid arthritis (RA) is a prevalent autoimmune disorder in which complex genetic predisposition interacts with multiple environmental factors to precipitate chronic and progressive immune-mediated joint inflammation. Currently, in most affected individuals, ongoing suppression of the inflammation is required to prevent irreversible damage and functional loss. The delineation of a protracted preclinical period in which autoimmunity is initially established and then evolves to become pathogenic provides unprecedented opportunities for interventions that have the potential to prevent the onset of this lifelong disease. Clinical trials aimed at assessing the impact of specific prevention strategies require the identification of individuals who are at high risk of future RA development. Currently, these risk factors include a strong family history of RA, and the detection of circulating RA-associated autoantibodies, particularly anti-citrullinated protein antibodies (ACPA). Yet, even in such individuals, there remains considerable uncertainty about the likelihood and the timeframe for future disease development. Thus, individuals who are approached to participate in such clinical trials are left weighing the risks and benefits of the prevention measures, while having large gaps in our current understanding. To address this challenge, we have undertaken longitudinal studies of the family members of Indigenous North American RA patients, this population being known to have a high prevalence of RA, early age of onset, and familial clustering of cases. Our studies have indicated that the concepts of "risk" and "prevention" need to be communicated in a culturally relevant manner, and proposed prevention interventions need to have an appropriate balance of effectiveness, safety, convenience, and cultural acceptability. We have focused our proposed prevention studies on immunomodulatory/anti-inflammatory nutritional supplements that appear to strike such a complex balance.

Efficacy of therapeutic fasting and plant-based diet in patients with rheumatoid arthritis (NutriFast): study protocol for a randomised controlled clinical trial

BACKGROUND

Previous studies have shown beneficial effects of therapeutic fasting and plant-based dietary interventions on disease activity in patients with rheumatoid arthritis (RA) for a duration of up to 1 year. To date, the effects of such interventions on the gut microbiome and on modern diagnostic markers in patients with RA have not been studied. This trial aims to investigate the clinical effects of therapeutic fasting and a plant-based diet in patients with RA, additionally considering current immunological diagnostic tools and microbiome analyses.

METHODS/DESIGN

This trial is an open-label, single-centre, randomised, controlled, parallel-group clinical trial. We will randomly assign 84 patients with RA under a stable standard therapy to either (1) therapeutic fasting followed by a plant-based dietary intervention or (2) to a conventional nutritional counselling focusing on an anti-inflammatory dietary pattern according to the recommendations of the Deutsche Gesellschaft für Ernährung (German society for nutrition). Primary outcome parameter is the group difference from baseline to 12 weeks on the Health Assessment Questionnaire (HAQ). Other secondary outcomes include established clinical criteria for disease activity and treatment response in RA (Disease Activity Score 28, Simple Disease Activity Index, ACR-Response Criteria), changes in self-reported health and physical functional ability, mood, stress, quality of life, dietary behaviour via 3-day food records and a modified Food Frequency Questionnaire, body composition, changes in the gut microbiome, metabolomics and cytometric parameters. Outcomes will be assessed at baseline and day 7, after 6 weeks, 12 weeks and after 6 months.

ETHICS AND DISSEMINATION

Ethical approval to process and analyse data, and to publish the results was obtained through the institutional review board of Charité-Universitätsmedizin Berlin. Results of this trial will be disseminated through peer-reviewed publications and scientific presentations.

TRIAL REGISTRATION NUMBER

NCT03856190.

Probiotic Supplementation for Rheumatoid Arthritis: A Promising Adjuvant Therapy in the Gut Microbiome Era

Rheumatoid arthritis (RA) is a chronic immune-mediated inflammatory disease that ultimately leads to joint destruction and functional disability. Although the exact etiology of RA is not fully understood, it is well established that gut microbiota (GM) plays a vital role in the pathogenesis of RA, with accumulating evidence suggesting that gut dysbiosis induces a chronic inflammatory response that may be linked to disease development. Of interest, patients with RA have significant changes in the intestinal microbiota compared to healthy controls, and several studies have suggested the use of probiotics as a possible adjuvant therapy for RA. Benefits of probiotic supplementation were reported in animal models of arthritis and human studies, but the current evidence regarding the effect of probiotic supplementation in the management of RA remains insufficient to make definite recommendations. Several different strains of Lactobacillus and Bifidobacteria, as single species or in mixed culture, have been investigated, and some have demonstrated beneficial effects on disease activity in RA human subjects. As of now, L.casei probiotic bacteria seems to be the strongest candidate for application as adjuvant therapy for RA patients. In this review, we highlight the role of GM in the development and progression of RA and summarize the current knowledge on the use of probiotics as a potential adjuvant therapy for RA. We also review the proposed mechanisms whereby probiotics regulate inflammation. Finally, the role of fermented foods is discussed as a possible alternative to probiotic supplements since they have also been reported to have health benefits.

Intestinal barrier dysfunction plays an integral role in arthritis pathology and can be targeted to ameliorate disease

Background

Evidence suggests an important role for gut-microbiota dysbiosis in the development of rheumatoid arthritis (RA). The link between changes in gut bacteria and the development of joint inflammation is missing. Here, we address whether there are changes to the gut environment and how they contribute to arthritis pathogenesis.

Methods

We analyzed changes in markers of gut permeability, damage, and inflammation in peripheral blood and serum of RA patients. Serum, intestines, and lymphoid organs isolated from K/BxN mice with spontaneous arthritis or from wild-type, genetically modified interleukin (IL)-10R^−/−or claudin-8^−/−mice with induced arthritis were analyzed by immunofluorescence/histology, ELISA, and flow cytometry.

Findings

RA patients display increased levels of serum markers of gut permeability and damage and cellular gut-homing markers, both parameters positively correlating with disease severity. Arthritic mice display increased gut permeability from early stages of disease, as well as bacterial translocation, inflammatory gut damage, increases in interferon γ (IFNγ)⁺and decreases in IL-10⁺intestinal-infiltrating leukocyte frequency, and reduced intestinal epithelial IL-10R expression. Mechanistically, both arthritogenic bacteria and leukocytes are required to disrupt gut-barrier integrity. We show that exposing intestinal organoids to IFNγ reduces IL-10R expression by epithelial cells and that mice lacking epithelial IL-10R display increased intestinal permeability and exacerbated arthritis. Claudin-8^−/−mice with constitutively increased gut permeability also develop worse joint disease. Treatment of mice with AT-1001, a molecule that prevents development of gut permeability, ameliorates arthritis.

Conclusions

We suggest that breakdown of gut-barrier integrity contributes to arthritis development and propose restoration of gut-barrier homeostasis as a new therapeutic approach for RA.

Funding

Funded by Versus Arthritis (21140 and 21257) and UKRI/MRC (MR/T000910/1).

Serum gut-permeability markers LPB, LPS, and I-FABP are increased in RA

Mice with arthritis have increased gut permeability and intestinal inflammation

Both bacteria and leukocytes are needed to disrupt gut-barrier integrity

Prevention of gut-barrier dysfunction in arthritis ameliorates joint inflammation

Rheumatoid arthritis is an autoimmune disorder characterized by chronic joint inflammation. Accumulating evidence suggests that changes in the composition of the bacteria residing in the gut could be responsible for joint inflammation. Currently, it is unclear how bacteria or their products instruct cells of the immune system to become harmful and induce arthritis. Researchers at University College London have shown that, in arthritis, there is profound damage to the gut lining, which fails to work properly as a barrier, as well as an accumulation in the gut of white blood cells that cause inflammation. The authors show that, in arthritis, bacteria cross the prohibited border of the intestinal lining and that repairing gut permeability defects with specific drugs inhibits joint inflammation.

Effects of Wine and Its Microbial-Derived Metabolites on Intestinal Permeability Using Simulated Gastrointestinal Digestion/Colonic Fermentation and Caco-2 Intestinal Cell Models

This paper explores the effects of wine polyphenols on intestinal permeability in in vitro conditions. A red wine (2500 mg/L of gallic acid equivalents) was sequentially subjected to gastrointestinal and colonic digestion in the Dynamic Gastrointestinal Simulator (simgi^®) to obtain two simulated fluids: intestinal-digested wine (IDW) and colonic-digested wine (CDW). The two fluids were incubated with Caco-2 cell monolayers grown in Transwell^® inserts, and paracellular permeability was measured as transport of FITC-dextran. Non-significant decreases (p > 0.05) in paracellular permeability were found, which was attributed to the relatively low phenolic concentration in the solutions tested (15.6 and 7.8 mg of gallic acid equivalents/L for IDW and CDW, respectively) as quercetin (200 µM) and one of its microbial-derived phenolic metabolites, 3,4-dihydroxyphenylacetic acid (200 µM), led to significant decreases (p < 0.05). The expression of tight junction (TJ) proteins (i.e., ZO-1 and occludin) in Caco-2 cells after incubation with IDW and CDW was also determined. A slight increase in mRNA levels for occludin for both IDW and CDW fluids, albeit without statistical significance (p > 0.05), was observed. Analysis of the microbiome and microbial activity during wine colonic fermentation revealed relevant changes in the relative abundance of some families/genera (i.e., reduction in Bacteroides and an increase in Veillonella, Escherichia/Shigella and Akkermansia) as well as in the microbial production of SCFA (i.e., a significant increase in propionic acid in the presence of IDW), all of which might affect paracellular permeability. Both direct and indirect (microbiota-mediated) mechanisms might be involved in the protective effects of (wine) polyphenols on intestinal barrier integrity. Overall, this paper reinforces (wine) polyphenols as a promising dietary strategy to improve gut functionality, although further studies are needed to evaluate the effect on the intestinal barrier under different conditions.

Risk Factors for Developing Rheumatoid Arthritis in Patients With Undifferentiated Arthritis and Inflammatory Arthralgia

Currently, there is an increasing interest in treating patients at risk of rheumatoid arthritis (RA) to prevent the development of this chronic disease. In this sense, research has focused attention on the early identification of predictive factors of this disease. Autoantibodies and markers of systemic inflammation can be present before clinical arthritis and RA development. So, the phase of inflammatory arthralgia preceding clinical arthritis is an important part of the window of opportunity and, starting treatment might prevent progression to chronic arthritis. Additionally, the early diagnosis and treatment initiation, in patients with inflammatory arthritis at risk of persistence and/or erosive progression, are fundamental because may allow optimal clinical responses, better chances of achieving sustained remission, preventing irreversible organ damage and optimizing long-term outcomes. This review aims to give an overview of clinical risk factors for developing RA, both in suspected arthralgia and in undifferentiated arthritis. Besides taking into consideration the role of serological markers (immunological and acute phase reactants) and clinical features assessed at consultation such as: articular affection and patient's clinical perception. Other features as sociodemographic and environmental factors (lifestyle habits, microbiota, periodontal disease among others), have been included in this revision to give an insight on strategies to prevent development of RA and/or to treat it in early stages.

Cannabinoid-based therapy as a future for joint degeneration. Focus on the role of CB2 receptor in the arthritis progression and pain: an updated review

Over the last several decades, the percentage of patients suffering from different forms of arthritis has increased due to the ageing population and the increasing risk of civilization diseases, e.g. obesity, which contributes to arthritis development. Osteoarthritis and rheumatoid arthritis are estimated to affect 50-60% of people over 65 years old and cause serious health and economic problems. Currently, therapeutic strategies are limited and focus mainly on pain attenuation and maintaining joint functionality. First-line therapies are nonsteroidal anti-inflammatory drugs; in more advanced stages, stronger analgesics, such as opioids, are required, and in the most severe cases, joint arthroplasty is the only option to ensure joint mobility. Cannabinoids, both endocannabinoids and synthetic cannabinoid receptor (CB) agonists, are novel therapeutic options for the treatment of arthritis-associated pain. CB₁ receptors are mainly located in the nervous system; thus, CB₁ agonists induce many side effects, which limit their therapeutic efficacy. On the other hand, CB₂ receptors are mainly located in the periphery on immune cells, and CB₂ modulators exert analgesic and anti-inflammatory effects in vitro and in vivo. In the current review, novel research on the cannabinoid-mediated analgesic effect on arthritis is presented, with particular emphasis on the role of the CB₂ receptor in arthritis-related pain and the suppression of inflammation.

Interplay of Microbiota and Citrullination in the Immunopathogenesis of Rheumatoid Arthritis

Microbiota is a balanced ecosystem that has important functions to the host health including development, defense, digestion, and absorption of dietary fibers and minerals, vitamin synthesizes, protection, and training the host immune system. On the other hand, its dysbiosis is linked to many human diseases such as rheumatoid arthritis (RA). The RA is an inflammatory autoimmune disorder caused by genetic and environmental factors; microbiota may be considered as a risk environmental factor for it. Citrullination is a post-translation modification (PMT) that converts the amino acid arginine to amino acid citrulline in certain proteins. These citrullinated proteins are recognized as a foreign antigen by the immune system resulting in the upregulation of inflammatory action such as in RA. The current work highlights the effect of both gut and oral microbiota dysbiosis on the development of RA, as well as discusses how the alteration in microbiota composition leads to the overgrowth of some bacterial species that entangled in RA pathogenicity. The evidence suggested that some oral and gut microbial species such as Porphyromonas gingivalis and Prevotella copri, respectively, contribute to RA pathogenesis. During dysbiosis, these bacteria can mediate the citrullination of either human or bacteria proteins to trigger an immune response that leads to the generation of autoantibodies.

Rheumatoid arthritis and dietary interventions: systematic review of clinical trials

CONTEXT

The impact of various dietary interventions on rheumatoid arthritis (RA), characterized by immune-inflammatory response, has been subject to increased attention.

OBJECTIVE

A systematic review was conducted to update the current knowledge on the effects of nutritional, dietary supplement, and fasting interventions on RA outcomes.

DATA SOURCES

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, with prespecification of all methods, Medline and Embase were systematically searched for relevant articles.

DATA EXTRACTION

Data were extracted by 2 independent reviewers.

RESULTS

A total of 70 human studies were identified. Administration of omega-3 polyunsaturated fatty acids at high doses resulted in a reduction in RA disease activity and a lower failure rate of pharmacotherapy. Vitamin D supplementation and dietary sodium restriction were beneficial on some RA outcomes. Fasting resulted in significant but transient subjective improvements. While the Mediterranean diet demonstrated improvements in some RA disease activity measures, outcomes from vegetarian, elimination, peptide, or elemental diets suggested that responses are very individualized.

CONCLUSION

Some dietary approaches may improve RA symptoms and thus it is recommended that nutrition should be routinely addressed.

Regulation of the gut barrier by carbohydrates from diet - Underlying mechanisms and possible clinical implications

The gut barrier has been recognized as being of relevance in the pathogenesis of multiple different diseases ranging from inflammatory bowel disease, irritable bowel syndrome, inflammatory joint disease, fatty liver disease, and cardiometabolic disorders. The regulation of the gut barrier is, however, poorly understood. Especially, the role of food components such as sugars and complex carbohydrates has been discussed controversially in this respect. More recently, the intestinal microbiota has been proposed as an important regulator of the gut barrier. Whether the microbiota affects the barrier by its own, or whether food components such as carbohydrates mediate their effects through alterations of the microbiota composition or its metabolites, is still not clear. In this review, we will summarize the current knowledge on this topic derived from both animal and human studies and discuss data for possible clinical impact.