The Oral-Lung Microbiome Axis in Connective Tissue Disease-Related Interstitial Lung Disease.

Connective tissue disease-related interstitial lung disease (CTD-ILD) is a frequent and serious complication of CTD, leading to high morbidity and mortality. Unfortunately, its pathogenesis remains poorly understood; however, one intriguing contributing factor may be the microbiome of the mouth and lungs. The oral microbiome, which is a major source of the lung microbiome through recurrent microaspiration, is altered in ILD patients. Moreover, in recent years, several lines of evidence suggest that changes in the oral and lung microbiota modulate the pulmonary immune response and thus may play a role in the pathogenesis of ILDs, including CTD-ILD. Here, we review the existing data demonstrating oral and lung microbiota dysbiosis and possible contributions to the development of CTD-ILD in rheumatoid arthritis, Sjögren's syndrome, systemic sclerosis, and systemic lupus erythematosus. We identify several areas of opportunity for future investigations into the role of the oral and lung microbiota in CTD-ILD.

Gut microbiome profiling in systemic sclerosis: a metagenomic approach.

OBJECTIVES: The early gastrointestinal (GI) manifestation of systemic sclerosis (SSc) suggests a possible GI microbiota engagement in the pathophysiology and/or progression of SSc. Previous studies have revealed dysbiosis among Caucasian SSc patients. This study extends these findings to Asian SSc patients. METHODS: Adult SSc patients, stratified according to 1) on immunosuppressive (On-IS) drugs or 2) no immunosuppressive drugs (No-IS), and age-and-sex-matched healthy controls (HC) were recruited. Metagenomic sequencing of stool DNA was compared between SSc patients and HC, and between SSc (On-IS) and (No-IS) patients. Alpha and beta-diversity, taxonomic and functional profiling were evaluated. RESULTS: Twenty-three female SSc patients (12 On-IS; 11 No-IS; 5 diffuse and 18 limited SSc subtype) and 19 female HC, with median age of 54 years and 56 years, respectively, were recruited. Median SSc disease duration was 3.3 years. Alpha diversity was significantly higher in SSc versus HC (p=0.014) and in SSc (No-IS) versus HC (p=0.006). There was no significant difference in beta diversity between SSc and HC (p=0.307). At the phyla level, there were significantly increased abundance of Firmicutes and Actinobacteria in SSc versus HC, and reduced abundance of Bacteroidetes (all p<0.001). At the species level, there were significantly increased abundance of several Lactobacillus, Bifidobacterium, and Coprococcus species in SSc, and increased abundance of Odoribacter, Bacteroides and Prevotella species in HC. KEGG pathway analysis demonstrated distinct differences between SSc versus HC, and between SSc (No-IS) and SSc (On-IS). CONCLUSIONS: Using metagenomic sequencing, our study further underlines distinct alterations in microbiota profiling among Asian SSc patients.

Congruent microbiome signatures in fibrosis-prone autoimmune diseases: IgG4-related disease and systemic sclerosis.

BACKGROUND: Immunoglobulin G4-related disease (IgG4-RD) and systemic sclerosis (SSc) are rare autoimmune diseases characterized by the presence of CD4+ cytotoxic T cells in the blood as well as inflammation and fibrosis in various organs, but they have no established etiologies. Similar to other autoimmune diseases, the gut microbiome might encode disease-triggering or disease-sustaining factors. METHODS: The gut microbiomes from IgG4-RD and SSc patients as well as healthy individuals with no recent antibiotic treatment were studied by metagenomic sequencing of stool DNA. De novo assembly-based taxonomic and functional characterization, followed by association and accessory gene set enrichment analysis, were applied to describe microbiome changes associated with both diseases. RESULTS: Microbiomes of IgG4-RD and SSc patients distinctly separated from those of healthy controls: numerous opportunistic pathogenic Clostridium and typically oral Streptococcus species were significantly overabundant, while Alistipes, Bacteroides, and butyrate-producing species were depleted in the two diseases compared to healthy controls. Accessory gene content analysis in these species revealed an enrichment of Th17-activating Eggerthella lenta strains in IgG4-RD and SSc and a preferential colonization of a homocysteine-producing strain of Clostridium bolteae in SSc. Overabundance of the classical mevalonate pathway, hydroxyproline dehydratase, and fibronectin-binding protein in disease microbiomes reflects potential functional differences in host immune recognition and extracellular matrix utilization associated with fibrosis. Strikingly, the majority of species that were differentially abundant in IgG4-RD and SSc compared to controls showed the same directionality in both diseases. Compared with multiple sclerosis and rheumatoid arthritis, the gut microbiomes of IgG4-RD and SSc showed similar signatures; in contrast, the most differentially abundant taxa were not the facultative anaerobes consistently identified in inflammatory bowel diseases, suggesting the microbial signatures of IgG4-RD and SSc do not result from mucosal inflammation and decreased anaerobism. CONCLUSIONS: These results provide an initial characterization of gut microbiome ecology in fibrosis-prone IgG4-RD and SSc and reveal microbial functions that offer insights into the pathophysiology of these rare diseases.

A review and roadmap of the skin, lung and gut microbiota in systemic sclerosis.

As our understanding of the genetic underpinnings of SSc increases, questions regarding the environmental trigger(s) that induce and propagate SSc in the genetically predisposed individual emerge. The interplay between the environment, the immune system, and the microbial species that inhabit the patient's skin and gastrointestinal tract is a pathobiological frontier that is largely unexplored in SSc. The purpose of this review is to provide an overview of the methodologies, experimental study results and future roadmap for elucidating the relationship between the SSc host and his/her microbiome.

Helicobacter pylori and Upper Endoscopy in Systemic Sclerosis: A Cross-sectional Study in the Real World.

BACKGROUND/AIMS: A role for Helicobacter pylori in triggering systemic sclerosis (SSc) has been proposed, but data are conflicting. In previous studies, infection has been generally searched for by using serology. We designed this study to assess H. pylori prevalence in SSc patients with histology of gastric mucosa, considered the criterion standard for infection diagnosis. METHODS: This cross-sectional study enrolled 30 SSc patients who complained of upper gastrointestinal symptoms. All underwent upper endoscopy with gastric biopsies. Endoscopic alterations were recorded, and gastric mucosa biopsies were used for both histological examination and searching for H. pylori. The role for proton-pump inhibitor (PPI) therapy was considered. Fisher exact test was used for statistical analysis. RESULTS: Data of 28 SSc patients were available, 14 with ongoing PPI therapy. Helicobacter pylori infection at histology was detected in 14.3% patients, and it equally occurred in patients with or without PPI therapy. Erosive esophagitis/Barrett esophagus was detected in 26.6% of cases. Among patients with PPI therapy, 30% received half dose only. The prevalence of intestinal metaplasia was low (14.3%). Endoscopic esophageal alterations were significantly more frequent in those patients showing anti-Scl70 antibody positivity. CONCLUSIONS: This study showed that prevalence of H. pylori is very low in SSc patients, so that it seems not having a role in triggering SSc. Management of gastroesophageal diseases in SSc patients needs to be improved, and looking to the autoimmune profile may be of help. Thus, collaboration between rheumatologist and gastroenterologist is highly recommended.

Meta-analysis of differentially expressed microRNAs in systemic sclerosis.

OBJECTIVE: Emerging evidence suggests a possible role of microRNAs (miRNAs) that can regulate gene expression in the pathogenesis of systemic sclerosis (SSc). However, contradictory results have been reported on miRNA expression in SSc. We performed a meta-analysis to identify the consistently differentially expressed miRNAs in SSc across studies. METHODS: We performed a systematic search in PubMed using the terms "microRNAs OR Circulating MicroRNA OR miRNAs" AND "systemic sclerosis OR systemic scleroderma" to identify full-text English publications until 1 August, 2019. After quality assessment using Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2), we utilized RevMan 5.3 and Meta-Disc 1.4 to assess heterogeneity (I2 index and Q test P values) and perform effect size modeling. RESULTS: From 120 publications in the initial search, 16 studies on miRNA expression profiles in blood and/or dermal fibroblasts were selected after publication screening. The median number of samples in these studies was 36 (interquartile range 19-59, range 10-119). Meta-analysis revealed 8 differentially expressed miRNAs, of which miR-21 in blood, miR-29a, miR-155, and miR-196a in dermal fibroblasts, and let-7a in both serum and dermal fibroblast samples were most consistent across studies. These miRNAs have been implicated in immune activation, vascular damage, and fibroblast activation, which could potentially lead to the overproduction of collagen and extracellular protein. CONCLUSION: Studies of miRNA expression in SSc are limited and have used a relatively small number of samples. A meta-analysis of these reports reveals a cluster of differentially expressed miRNAs implicated in immune activation, vascular damage, and fibroblast activation that could play roles in SSc pathogenesis and serve as potential biomarkers.

The efficacy and safety of fecal microbiota transplantation in the treatment of systemic sclerosis: A protocol for systematic review and meta analysis.

BACKGROUND: Systemic sclerosis (SSc) is 1 of the most complex systemic autoimmune diseases.Accumulating evidence suggests that gut microbiota affect the development and function of the immune system and may play a role in the pathogenesis of autoimmune diseases. This new paradigm raises the possibility that many diseases result, at least partially, from microbiota-related dysfunction. This understanding invites the investigation of fecal microbiota transplantation (FMT) in the treatment of SSc. However, no study has specifically and systematically investigated the efficacy and safety of FMT in the treatment of SSc. Thus, this study will systematically and comprehensively appraise the efficacy and safety of FMT in the treatment of SSc. METHODS: We will search the following sources without restrictions for date, language, or publication status: PubMed, Web of Science,Cochrane Central Register of Controlled Trials (CENTRAL) Cochrane Library, EMBASE and China National Knowledge Infrastructure. We will apply a combination of Medical Subject Heading (MeSH) and free-text terms incorporating database-specific controlled vocabularies and text words to implement search strategies. We will also search the ongoing trials registered in the World Health Organization's International Clinical Trials Registry Platform. Besides, the previous relevant reviews conducted on FMT for SSc and reference lists of included studies will also be searched. RESULTS: This study will provide a reliable basis for the treatment of SSc with FMT. CONCLUSIONS: The findings will be an available reference to evaluate the efficacy and safety of FMT in the treatment of SSc. REGISTRATION NUMBER: INPLASY202060019.

Fecal microbiota transplantation in systemic sclerosis: A double-blind, placebo-controlled randomized pilot trial.

OBJECTIVES: Systemic sclerosis (SSc) is an auto-immune, multi organ disease marked by severe gastrointestinal (GI) involvement and gut dysbiosis. Here, we aimed to determine the safety and efficacy of fecal microbiota transplantation (FMT) using commercially-available anaerobic cultivated human intestinal microbiota (ACHIM) in SSc. METHODS: Ten patients with SSc were randomized to ACHIM (n = 5) or placebo (n = 5) in a double-blind, placebo-controlled 16-week pilot. All patients had mild to severe upper and lower GI symptoms including diarrhea, distention/bloating and/or fecal incontinence at baseline. Gastroduodenoscopy transfer of ACHIM or placebo was performed at weeks 0 and 2. Primary endpoints were safety and clinical efficacy on GI symptoms assessed at weeks 4 and 16. Secondary endpoints included changes in relative abundance of total, immunoglobulin (Ig) A- and IgM-coated fecal bacteria measured by 16s rRNA sequencing. RESULTS: ACHIM side effects were mild and transient. Two placebo controls experienced procedure-related serious adverse events; one developed laryngospasms at week 0 gastroduodenoscopy necessitating study exclusion whilst one encountered duodenal perforation during gastroduodenoscopy at the last study visit (week 16). Decreased bloating, diarrhea and/or fecal incontinence was observed in four of five patients in the FMT group (week 4 or/and 16) and in two of four in the placebo group (week 4 or 16). Relative abundance, richness and diversity of total and IgA-coated and IgM-coated bacteria fluctuated more after FMT, than after placebo. CONCLUSIONS: FMT of commercially-available ACHIM is associated with gastroduodenoscopy complications but reduces lower GI symptoms by possibly altering the gut microbiota in patients with SSc.

Effectiveness of Saccharomyces boulardii and Metronidazole for Small Intestinal Bacterial Overgrowth in Systemic Sclerosis.

BACKGROUND: Small intestinal bacterial overgrowth (SIBO) affects up to 60% of patients with systemic sclerosis (SSc), and it improves with antibiotics. The addition of probiotics could lead to better results. AIMS: To evaluate the efficacy and safety of Saccharomyces boulardii (SB) versus metronidazole (M) versus M + SB for 2 months, to reduce gastrointestinal symptoms and SIBO assessed with hydrogen breath test in SSc. METHODS: An open pilot clinical trial performed in forty patients with SIBO and SSc (ACR-EULAR 2013) who signed informed consent. Three groups were assigned: M, SB, and M + SB, for 2 months. Hydrogen was measured in parts per million with a hydrogen breath test to evaluate SIBO. The National Institutes of Health Patient-Reported Outcomes Measurement Information System (NIH-PROMIS) questionnaire was applied to quantify gastrointestinal symptoms with a raw score of eight symptoms. This study is registered in ClinicalTrials.gov with the following ID: NCT03692299. RESULTS: Baseline characteristics were similar between groups. The average age was 53.2 ± 9.3 years, and the evolution of SSc was 13.5 (1-34) years. After 2 months of treatment, SIBO was eradicated in 55% of the M + SB group: 33% of SB, and 25% of M. The SB and M + SB groups had decreased diarrhea, abdominal pain, and gas/bloating/flatulence, but M remained unchanged. Reductions in expired hydrogen at 45 to 60 min were as follows: M + SB 48% and 44%, M 18% and 20%, and SB 53% and 60% at the first and second months, respectively (p < 0.01). Adverse effects were epigastric burning and constipation in M (53%) and M + SB (36%), and flatulence/diarrhea in SB (22%). CONCLUSIONS: Metronidazole treatment is partially effective in SIBO, but S. boulardii in monotherapy or in combination improves the gastrointestinal outcomes in SSc.

CXCL4 assembles DNA into liquid crystalline complexes to amplify TLR9-mediated interferon-α production in systemic sclerosis.

Systemic sclerosis (SSc) is a chronic autoimmune disease characterized by fibrosis and vasculopathy. CXCL4 represents an early serum biomarker of severe SSc and likely contributes to inflammation via chemokine signaling pathways, but the exact role of CXCL4 in SSc pathogenesis is unclear. Here, we elucidate an unanticipated mechanism for CXCL4-mediated immune amplification in SSc, in which CXCL4 organizes "self" and microbial DNA into liquid crystalline immune complexes that amplify TLR9-mediated plasmacytoid dendritic cell (pDC)-hyperactivation and interferon-α production. Surprisingly, this activity does not require CXCR3, the CXCL4 receptor. Importantly, we find that CXCL4-DNA complexes are present in vivo and correlate with type I interferon (IFN-I) in SSc blood, and that CXCL4-positive skin pDCs coexpress IFN-I-related genes. Thus, we establish a direct link between CXCL4 overexpression and the IFN-I-gene signature in SSc and outline a paradigm in which chemokines can drastically modulate innate immune receptors without being direct agonists.

Effect of probiotics on gastrointestinal symptoms and immune parameters in systemic sclerosis: a randomized placebo-controlled trial.

OBJECTIVES: Changes in the intestinal microbiota have been associated with the pathogenesis of SSc. Probiotics act by modulating the microbiome and the immune response. This study aimed to evaluate the efficacy of probiotics on gastrointestinal (GI) symptoms and immune responses in SSc patients. METHODS: Patients with SSc with a moderate-severe total score on the University of California Los Angeles Scleroderma Clinical Trials Consortium Gastrointestinal Tract 2.0 (UCLA GIT 2.0) instrument were randomly assigned to receive a daily dose of probiotics (Lactobacillus paracasei, Lactobacillus rhamnosus, Lactobacillus acidophillus and Bifidobacterium lactis, 109 colony-forming units per capsule) or placebo for 8 weeks. The primary endpoint was improvement in the UCLA GIT 2.0 total score after 8 weeks. Secondary outcomes included changes in Th1, Th2, Th17 and regulatory T cell circulating levels and in the HAQ Disability Index (HAQ-DI) score. Parameters were assessed at baseline and after 4 and 8 weeks of treatment. RESULTS: A total of 73 patients were randomized to receive probiotics (n = 37) or placebo (n = 36). After 8 weeks, there was no difference in the UCLA GIT 2.0 score between the two groups. At week 8, the probiotic group showed a significant decrease in the proportion of Th17 cells compared with placebo (P = 0.003). There was no difference in the proportion of Th1, Th2 and regulatory T cells or in the HAQ-DI score between the groups. CONCLUSION: Probiotics did not improve GI symptoms in SSc patients. The reduction in Th17 cell levels suggests an immunomodulatory effect of probiotics on SSc. TRIAL REGISTRATION: ClinicalTrials.gov (http://clinicaltrials.gov), NCT02302352.

Microbiome dysbiosis is associated with disease duration and increased inflammatory gene expression in systemic sclerosis skin.

BACKGROUND: Infectious agents have long been postulated to be disease triggers for systemic sclerosis (SSc), but a definitive link has not been found. Metagenomic analyses of high-throughput data allows for the unbiased identification of potential microbiome pathogens in skin biopsies of SSc patients and allows insight into the relationship with host gene expression. METHODS: We examined skin biopsies from a diverse cohort of 23 SSc patients (including lesional forearm and non-lesional back samples) by RNA-seq. Metagenomic filtering and annotation was performed using the Integrated Metagenomic Sequencing Analysis (IMSA). Associations between microbiome composition and gene expression were analyzed using single-sample gene set enrichment analysis (ssGSEA). RESULTS: We find the skin of SSc patients exhibits substantial changes in microbial composition relative to controls, characterized by sharp decreases in lipophilic taxa, such as Propionibacterium, combined with increases in a wide range of gram-negative taxa, including Burkholderia, Citrobacter, and Vibrio. CONCLUSIONS: Microbiome dysbiosis is associated with disease duration and increased inflammatory gene expression. These data provide a comprehensive portrait of the SSc skin microbiome and its association with local gene expression, which mirrors the molecular changes in lesional skin.

Prevalence and associated factors of small intestinal bacterial overgrowth among systemic sclerosis patients.

BACKGROUND: Small intestinal bacterial overgrowth (SIBO) results in nutrient malabsorption and malnutrition, thereby increasing the morbidity and mortality in systemic sclerosis (SSc) patients. OBJECTIVES: To evaluate the prevalence and associated factors of SIBO in SSc patients. METHOD: A cross-sectional study was conducted between July 2015 and January 2016 in SSc patients over 18, using the glucose H2 /CH4 breath test to evaluate SIBO. RESULTS: Eighty-nine SSc patients (30 male and 59 female) underwent the glucose H2 /CH4 breath test. The mean age was 54.4. Twelve participants were positive for the glucose H2 /CH4 breath test, yielding a SIBO prevalence of 13.5% (95% CI 7.2-22.4) among SSc patients. A multivariate analysis revealed that duration of disease >5 years was significantly associated with SIBO (adjusted odds ratio 9.38; 95% CI 1.09-80.47). CONCLUSION: The prevalence of SIBO, using the glucose H2 /CH4 breath test, is not common among Thai SSc patients. However, a positive result was associated with longer duration of disease.

Small intestinal bacterial overgrowth in systemic sclerosis: a review of the literature.

Systemic sclerosis (SSc) is a chronic, connective tissue disease with an autoimmune pattern characterized by inflammation, fibrosis and microcirculation changes leading to internal organs malfunctions. Recently, the presence of uncharacteristic gastrointestinal symptoms in the course of SSc has been underlined. The possible cause of such clinical presentation is the small intestinal bacterial overgrowth (SIBO). Nevertheless, these manifestations resulting from gastrointestinal tract hypomotility may occur in numerous disease entities. The systematic review of the literature was performed on MEDLINE database using the relevant MeSH terms including all sub-headings. After further investigation, the initial number of 56 records was limited to 7 results. The study analysis showed an increased presence of SIBO in 39% of patients suffering from SSc. The average SSc duration was longer in SSc patients with coexisting SIBO. SIBO remains a diagnostic and therapeutic challenge and therefore is a significant clinical problem among patients suffering from SSc.

Treatment of small intestinal bacterial overgrowth in systemic sclerosis: a systematic review.

Objectives: Almost all patients with SSc have gastrointestinal manifestations. Small intestinal bacterial overgrowth (SIBO) occurs in 30-60% of patients and leads to malnutrition and impaired quality of life. Recent systematic reviews have reported efficacy of treatments for SIBO, but these are not specific to patients with SSc. We conducted a systematic review of the evidence for all possible SIBO treatments in the SSc population. Methods: The following databases were searched: MEDLINE, EMBASE and the Cochrane Library, from database inception to 1 January 2017. All evidence for all possible SIBO treatments including antibiotics, prokinetics, probiotics and alternative treatments was included. Treatment outcomes included symptomatic relief or demonstrated SIBO eradication. Results: Of 5295 articles, five non-randomized studies were reviewed with a total of 78 SSc patients with SIBO. One trial assessed octreotide while the remaining four trials investigated the effectiveness of ciprofloxacin, rifaximin, norfloxacin and metronidazole, and the combination of amoxicillin, ciprofloxacin and metronidazole. Studies were generally of low quality and most were un-controlled. Conclusion: Data indicate that, for some SSc patients, antibiotics can eradicate SIBO. There is a paucity of data reporting the effectiveness of either prokinetics or probiotics in SSc.

Update on the Gastrointestinal Microbiome in Systemic Sclerosis.

PURPOSE OF REVIEW: Accumulating evidence suggests that gut microbiota affect the development and function of the immune system and may play a role in the pathogenesis of autoimmune diseases. The purpose of this review is to summarize recent studies reporting gastrointestinal microbiota aberrations associated with the systemic sclerosis disease state. RECENT FINDINGS: The studies described herein have identified common changes in gut microbial composition. Specifically, patients with SSc have decreased abundance of beneficial commensal genera (e.g., Faecalibacterium, Clostridium, and Bacteroides) and increased abundance of pathobiont genera (e.g., Fusobacterium, Prevotella, Erwinia). In addition, some studies have linked specific genera with the severity of gastrointestinal symptoms in systemic sclerosis. More research is needed to further characterize the gastrointestinal microbiota in systemic sclerosis and understand how microbiota perturbations can affect inflammation, fibrosis, and clinical outcomes. Interventional studies aimed at addressing/correcting these perturbations, either through dietary modification, pro/pre-biotic supplementation, or fecal transplantation, may lead to improved outcomes for patients with systemic sclerosis.

Helicobacter pylori infection in systemic sclerosis: a systematic review and meta-analysis of observational studies.

OBJECTIVES: It has been proposed that Helicobacter pylori (H.pylori) infection causes several extra-gastrointestinal disorders. However, the role of H.pylori infection in the pathogenesis of systemic sclerosis (SSc) is still debatable. This meta-analysis is aimed at exploring the association between SSc and H.pylori infection. METHODS: A comprehensive search of the MEDLINE and EMBASE databases was performed from inception through February 2018. The inclusion criterion was observational studies evaluating H.pylori infection in SSc. The pooled odds ratio (OR) of H.pylori infection and their 95% confidence interval (CI) were calculated using a random-effects meta-analysis to compare risk between SSc patients and healthy controls. The between-study heterogeneity of effect-size was quantified using the Q statistic and I2. RESULTS: Data were extracted from 8 observational studies involving 1,446 subjects. The pooled results demonstrated an increased H.pylori infection in SSc compared with healthy controls (OR=2.10; 95% CI: 1.57-2.82, p value<0.01, I2=13%). Subgroup analysis showed an increased risk of H.pylori infection measured with H.pylori ELISA test (OR=2.49; 95% CI: 1.82-3.40, p value<0.01, I2=0%). CONCLUSIONS: Our study has shown that patients with SSc have an increased prior existence of H.pylori infection. This finding implies that the role of previous infection may cause an abnormal immunological cascade in the pathogenesis of SSc. Further studies that could elucidate the inflammatory response in the pathogenesis of SSc are warranted.

Microbial and metabolic multi-omic correlations in systemic sclerosis patients.

Intestinal microbiota has been associated with systemic autoimmune diseases, yet the functional consequences of these associations are elusive. We characterized the fecal microbiota (16S rRNA gene amplification and sequencing) and the plasma metabolome (high-performance liquid chromatography coupled to mass spectrometry) in 59 patients with systemic sclerosis (SSc) and 28 healthy controls (HCs). Microbial and metabolic data were cross-correlated to find meaningful associations after extensive data mining analysis and internal validation. Our data show that a reduced model of nine bacteria is capable of differentiating HCs from SSc patients. SSc gut microbiota is characterized by a reduction in protective butyrate-producing bacteria and by an increase in proinflammatory noxious genera, especially Desulfovibrio. From the metabolic point of view, a multivariate model with 17 metabolite intermediates well distinguished cases from controls. The most interesting peaks we found were identified as glycerophospholipid metabolites and benzene derivatives. The microbial and metabolic data showed significant interactions between Desulfovibrio and alpha-N-phenylacetyl-l-glutamine and 2,4-dinitrobenzenesulfonic acid. Our data suggest that in SSc, intestinal microbiota is characterized by proinflammatory alterations subtly entwined with the metabolic state. Desulfovibrio is a relevant actor in gut dysbiosis that may promote intestinal damage and influence amino acid metabolism.

The Microbiome in Connective Tissue Diseases and Vasculitides: An Updated Narrative Review.

OBJECTIVE: To provide a narrative review of the most recent data concerning the involvement of the microbiome in the pathogenesis of connective tissue diseases (CTDs) and vasculitides. METHODS: The PubMed database was searched for articles using combinations of words or terms that included systemic lupus erythematosus, systemic sclerosis, autoimmune myositis, Sjögren's syndrome, undifferentiated and mixed CTD, vasculitis, microbiota, microbiome, and dysbiosis. Papers from the reference lists of the articles and book chapters were reviewed, and relevant publications were identified. Abstracts and articles written in languages other than English were excluded. RESULTS: We found some evidence that dysbiosis participates in the pathogenesis of systemic lupus erythematosus, systemic sclerosis, Sjögren's syndrome, and Behçet's disease, but there are still few data concerning the role of dysbiosis in other CTDs or vasculitides. CONCLUSIONS: Numerous studies suggest that alterations in human microbiota may be involved in the pathogenesis of inflammatory arthritides as a result of the aberrant activation of the innate and adaptive immune responses. Only a few studies have explored the involvement of dysbiosis in other CTDs or vasculitides, and further research is needed.