Connection between the Gut Microbiome, Systemic Inflammation, Gut Permeability and FOXP3 Expression in Patients with Primary Sjögren's Syndrome

Exploring the role of gut microbiome in autoimmune diseases: A comprehensive review

As the industrialized society advances, there has been a gradual increase in the prevalence of autoimmune disorders. A probe into the fundamental causes has disclosed several factors in modern society that have an influence on the gut microbiome. These dramatic shifts in the gut microbiome are likely to be one of the reasons for the disarray in the immune system, and the relationship between the immune system and the gut microbiome emerging as a perennial hot topic of research. This review enumerates the findings from sequencing studies of gut microbiota on seven autoimmune diseases (ADs): Rheumatoid Arthritis (RA), Systemic Lupus Erythematosus (SLE), Ankylosing Spondylitis (AS), Systemic Sclerosis (SSc), Sjögren's Syndrome (SjS), Juvenile Idiopathic Arthritis (JIA), and Behçet's Disease (BD). It aims to identify commonalities in changes in the gut microbiome within the autoimmune disease cohort and characteristics specific to each disease. The dysregulation of the gut microbiome involves a disruption of the internal balance and the balance between the external environment and the host. This dysregulation impacts the host's immune system, potentially playing a role in the development of ADs. Damage to the gut epithelial barrier allows potential pathogens to translocate to the mucosal layer, contacting epithelial cells, disrupting tight junctions, and being recognized by antigen-presenting cells, which triggers an immune response. Primed T-cells assist B-cells in producing antibodies against pathogens; if antigen mimicry occurs, an immune response is generated in extraintestinal organs during immune cell circulation, clinically manifesting as ADs. However, current research is limited; advancements in sequencing technology, large-scale cohort studies, and fecal microbiota transplantation (FMT) research are expected to propel this field to new peaks.

Fecal microbiota transplantation for the treatment of chronic inflammatory skin diseases

The regulation of immune functions and the maintenance of homeostasis in the internal environment are both integral to human gut microbiota (GM). If GM is disturbed, it can result in a range of autoimmune diseases, including chronic inflammatory skin conditions. Chronic inflammatory skin diseases driven by T or B-cell-mediated immune reactions are complex, including the most prevalent diseases and some rare diseases. Expanding knowledge of GM dysbiosis in chronic inflammatory skin diseases has emerged. The GM has some causal roles in the pathogenesis of these skin conditions. Targeting microbiota treatment, particularly fecal microbiota transplantation (FMT), is considered to be a promising strategy. FMT was commonly used in intestinal diseases by reshaping and balancing GM, serving as a reasonable administration in these skin inflammatory diseases. This paper summarizes the existing knowledge of GM dysbiosis in chronic inflammatory skin diseases and the research data on FMT treatment for such conditions.

Gut microbiota and eye diseases: A review

Recent studies reveal that alterations in gut microbiota play a significant role in the progression of various diseases, including those affecting the eyes. The association between gut microbiota and eye health is an emerging focus of research. This review seeks to summarize the connection between the gut microbiome and specific eye conditions, such as ocular surface diseases, funduscopic disorders and immune-mediated eye diseases. Gut microbiota may influence these conditions by regulating the immune system or altering metabolites, thereby contributing to disease development. Strategies like probiotics, antibiotics, dietary modifications, and fecal transplants show promise in addressing these issues. This review examines how the gut microbiome may be linked to the pathogenesis of eye diseases, providing fresh therapeutic perspectives for ophthalmology.

Microbiome as an endocrine organ and its relationship with eye diseases: Effective factors and new targeted approaches

Microbiome is an endocrine organ that refers to both the complicated biological system of microbial species that colonize our bodies and their genomes and surroundings. Recent studies confirm the connection between the microbiome and eye diseases, which are involved in the pathogenesis of eye diseases, including age-related macular disorders, diabetic retinopathy, glaucoma, retinitis pigmentosa, dry eye, and uveitis. The aim of this review is to investigate the microbiome in relation to eye health. First, a brief introduction of the characteristics of the gut microorganisms terms of composition and work, the role of dysbiosis, the gut microbiome and the eye microbiome in the progression of eye illnesses are highlighted, then the relationship among the microbiome and the function of the immune system and eye diseases, the role of inflammation and aging and the immune system, It has been reviewed and finally, the control and treatment goals of microbiome and eye diseases, the role of food factors and supplements, biotherapy and antibiotics in relation to microbiome and eye health have been reviewed.

The Potential Role of Butyrate in the Pathogenesis and Treatment of Autoimmune Rheumatic Diseases

The gut microbiota is a complex ecosystem of microorganisms residing in the human gastrointestinal tract, playing a crucial role in various biological processes and overall health maintenance. Dysbiosis, an imbalance in the composition and function of the gut microbiota, is linked to systemic autoimmune diseases (SAD). Short-chain fatty acids (SCFAs), especially butyrate, produced by the gut microbiota through the fermentation of dietary fibers, play a significant role in immunomodulation and maintaining intestinal homeostasis. Butyrate is essential for colonocyte energy, anti-inflammatory responses, and maintaining intestinal barrier integrity. Studies show reduced butyrate-producing bacteria in SAD patients, suggesting that increasing butyrate levels could have therapeutic benefits. Butyrate's anti-inflammatory effects and its potential therapeutic role have been studied in rheumatoid arthritis, Sjogren's syndrome, systemic lupus erythematosus, systemic sclerosis, and Behçet's disease. Despite promising in vitro and animal model results, human studies are limited, and the optimal strategies for modulating dysbiosis in SADs remain elusive. This review explores the current evidence on the immunoregulatory role of butyrate and its potential therapeutic effects in SAD.

The relationship between dry eye disease and human microbiota: A review of the science

A complex relationship exists between human microbiota and the risk for ophthalmic disease. While the homeostatic composition of human microbiota is still being established, including what defines dysbiosis (i.e. changes in diversity and abundance), pilot research has begun to identify the potential influence of demographics, geography, and co-morbidities on the microbiota and describe their impact on ocular health. This review specifically focuses on the scientific relationships of the human oral and gut microbiota to dry eye disease (DED), a set of conditions impacting the tear film and ocular surface. Although data are sparse and often conflict across studies, the literature generally supports associations between microbial imbalance (dysbiosis) and DED and alterations in microbial diversity and abundance to specific aspects of DED. This review examines the relevant science and mechanistic relationships linking gut and oral dysbiosis and DED. Various physiochemical factors and therapeutic approaches that alter microbiota, including medications and fecal transplants are examined in relation to DED.

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

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

Reconstruction of Sjögren's syndrome-like sialadenitis by a defined disease specific gut-reactive single TCR and an autoantibody

Lymphocytes such as CD4+ T cells and B cells mainly infiltrate the salivary glands; however, the precise roles and targets of autoreactive T cells and autoantibodies in the pathogenesis of Sjögren's Syndrome (SS) remain unclear. This study was designed to clarify the role of autoreactive T cells and autoantibodies at the single-cell level involved in the development of sialadenitis. Infiltrated CD4+ T and B cells in the salivary glands of a mouse model resembling SS were single-cell-sorted, and their T cell receptor (TCR) and B cell receptor (BCR) sequences were analyzed. The predominant TCR and BCR clonotypes were reconstituted in vitro, and their pathogenicity was evaluated by transferring reconstituted TCR-expressing CD4+ T cells into Rag2-/- mice and administering recombinant IgG in vivo. The reconstitution of Th17 cells expressing TCR (#G) in Rag2-/- mice resulted in the infiltration of T cells into the salivary glands and development of sialadenitis, while an autoantibody (IgGr22) was observed to promote the proliferation of pathogenic T cells. IgGr22 specifically recognizes double-stranded RNA (dsRNA) and induces the activation of dendritic cells, thereby enhancing the expression of IFN signature and inflammatory genes. TCR#G recognizes antigens related to the gut microbiota. Antibiotic treatment severely reduces the activation of TCR#G-expressing Th17 cells and suppresses sialadenitis development. These data suggest that the anti-dsRNA antibodies and, TCR recognizing the gut microbiota involved in the development of sialadenitis like SS. Thus, our model provides a novel strategy for defining the roles of autoreactive TCR and autoantibodies in the development and pathogenesis of SS.

Analysis of the mucosal chemokines CCL28, CXCL14, and CXCL17 in dry eye disease: An in vitro and clinical investigation

Mucosal chemokines have antimicrobial properties and play an important role in mucosal immunity. However, little is known about their expression on the ocular surface. This study aimed to analyze the expression of the mucosal chemokines CCL28, CXCL14 and CXCL17 in corneal and conjunctival epithelial cells under in vitro dry eye (DE) conditions, and in conjunctival samples from healthy subjects and DE patients. Human corneal epithelial cells (HCE) and immortalized human conjunctival epithelial cells (IM-HConEpiC) were incubated under hyperosmolar (400-500 mOsM) or inflammatory (TNF-α 25 ng/mL) conditions for 6 h and 24 h to measure CCL28, CXCL14, and CXCL17 gene expression by RT-PCR and their secretion by immunobead-based analysis (CCL28, CXCL14) and ELISA (CXCL17). Additionally, twenty-seven DE patients and 13 healthy subjects were included in this study. DE-related questionnaires (OSDI, mSIDEQ and NRS) evaluated symptomatology. Ocular surface integrity was assessed using vital staining. Tactile sensitivity was measured with Cochet-Bonnet esthesiometer, and mechanic and thermal (heat and cold) sensitivity using Belmonte's non-contact esthesiometer. Subbasal nerve plexus and dendritic cell density were analyzed by in vivo confocal microscopy. Conjunctival cells from participants were collected by impression cytology to measure mucosal chemokines gene expression by RT-PCR. Our results showed that HCE and IM-HConEpiC cells increased CCL28, CXCL14, and CXCL17 secretion under hyperosmolar conditions. The gene expression of CCL28 was significantly upregulated in conjunctival samples from DE patients. CCL28 expression correlated positively with symptomatology, corneal staining, heat sensitivity threshold, and dendritic cell density. CXCL14 expression correlated positively with age, ocular pain, conjunctival staining, tactile sensitivity, and image reflectivity. CXCL17 expression correlated positively with corneal staining. These results suggest that corneal and conjunctival epithelial cells could be a source of CCL28, CXCL14, and CXCL17 on the ocular surface and that CCL28 might be involved in DE pathogenesis.

Association between primary Sjögren's syndrome and gut microbiota disruption: a systematic review and meta-analysis

Evidence of gut microbiota disruption for numerous autoimmune diseases has accumulated. Recently, the relationship between the microbiota and primary Sjögren's disease has been increasingly investigated but has yet to be systematically elucidated. Therefore, a meta-analysis of publications dealing on topic was conducted. Case-control studies comparing primary Sjögren's syndrome patients and healthy controls (HCs) were systematically searched in nine databases from inception to March 1, 2023. The primary result quantitatively evaluated in this meta-analysis was the α-diversity. The secondary results qualitatively extracted and analyzed were the β-diversity and relative abundance. In total, 22 case-control studies covering 915 pSS patients and 2103 HCs were examined. The quantitative analysis revealed a slight reduction in α-diversity in pSS patients compared to HCs, with a lower Shannon-Wiener index (SMD =  - 0.46, (- 0.68, - 0.25), p < 0.0001, I2 = 71%), Chao1 richness estimator (SMD =  - 0.59, (- 0.86, - 0.32), p < 0.0001, I2 = 81%), and ACE index (SMD =  - 0.92, (- 1.64, - 0.19), p = 0.01, I2 = 86%). However, the Simpson index (SMD = 0.01, (- 0.43, 0.46) p = 0.95, I2 = 86%) was similar in the two groups. The β-diversity significantly differed between pSS patients and HCs. Variations in the abundance of specific microbes and their metabolites and potential functions contribute to the pSS pathogenesis. Notably, the abundance of the phylum Firmicutes decreased, while that of Proteobacteria increased. SCFA-producing microbes including Ruminococcaceae, Lachnospiraceae, Faecalibacterium, Butyricicoccus, and Eubacterium hallii were depleted. In addition to diversity, the abundances of some specific microbes were related to clinical parameters. According to this systematic review and meta-analysis, gut microbiota dysbiosis, including reduced diversity, was associated with proinflammatory bacterium enrichment and anti-inflammatory bacterium depletion in pSS patients. Further research on the relationship between the gut microbiota and pSS is warranted.

Human umbilical cord mesenchymal stem cells improve disease characterization of Sjogren's syndrome in NOD mice through regulation of gut microbiota and Treg/Th17 cellular immunity

BACKGROUND

For the unclear pathogenesis of Sjogren's syndrome (SS), further exploration is necessary. Mesenchymal stem cells (MSCs) and derived exosomes (MSCs-exo) have exhibited promising results in treating SS.

OBJECT

This study aimed to investigate the effect and mechanism of human umbilical cord MSCs (UC-MSCs) on SS.

METHODS

Nonobese Diabetic (NOD) mouse splenic T cells were co-cultured with UC-MSCs and UC-MSCs-exo, and interferon-gamma (IFN-γ), interleukin (IL)-6, IL-10, prostaglandin E2 (PGE2), and transforming growth factor-β1 (TGF-β1) levels in the supernatant were assessed by quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay. Co-cultured T cells were injected into NOD mice via the tail vein. The inflammatory cell infiltration in the intestine and the submandibular gland was characterized by hematoxylin-eosin staining. Treg/Th17 homeostasis within the spleen was determined by flow cytometry. Gut microbiota was detected by 16S rRNA sequencing, and the relationship between differential microbiota and Treg/Th17 cytokines was analyzed by the Pearson correlation coefficient.

RESULTS

UC-MSCs, UC-MSCs-exo, and NOD mouse splenic T cells were successfully cultured and identified. After T cells were co-cultured with UC-MSCs and UC-MSCs-exo, both IFN-γ and IL-6 were decreased while IL-10, PGE2, and TGF-β1 were increased in transcriptional and translational levels. UC-MSCs and UC-MSCs-exo partially restored salivary secretion function, reduced Ro/SSA antibody and α-Fodrin immunoglobulin A levels, reduced inflammatory cell infiltration in the intestine and submandibular gland, raised proportion of Treg cells, decreased IFN-γ, IL-6, IL-2, IL-17, lipopolysaccharide, and tumor necrosis factor-alpha levels, and raised IL-10, Foxp3, and TGF-β1 levels by affecting co-cultured T cells. The intervention of UC-MSCs and UC-MSCs-exo improved intestinal homeostasis in NOD mice by increasing microbiota diversity and richness. Additionally, differential microbiota was significantly associated with Treg/Th17 cytokine levels.

CONCLUSION

Human UC-MSCs and UC-MSCs-exo improved disease characterization of SS in NOD mice through regulation of gut microbiota and Treg/Th17 cellular immunity.

Compositional and functional aberrance of the gut microbiota in treatment-naïve patients with primary Sjögren's syndrome

OBJECTIVES

To investigate the compositional and functional characteristics of the gut microbiota in primary Sjögren's syndrome (pSS) and compare them with those in systemic lupus erythematosus (SLE).

METHODS

Stool samples from 78 treatment-naïve pSS patients and 78 matched healthy controls were detected by shotgun metagenomic sequencing and compared with those from 49 treatment-naïve SLE patients. The virulence loads and mimotopes of the gut microbiota were also assessed by sequence alignment.

RESULTS

The gut microbiota of treatment-naïve pSS patients had lower richness and evenness and showed a different community distribution than that of healthy controls. The microbial species enriched in the pSS-associated gut microbiota included Lactobacillus salivarius, Bacteroides fragilis, Ruminococcus gnavus, Clostridium bartlettii, Clostridium bolteae, Veillonella parvula, and Streptococcus parasanguinis. Lactobacillus salivarius was the most discriminating species in the pSS patients, especially in those with interstitial lung disease (ILD). Among the differentiating microbial pathways, the superpathway of l-phenylalanine biosynthesis was also further enriched in pSS complicated with ILD. There were more virulence genes carried by the gut microbiota in pSS patients, most of which encoded peritrichous flagella, fimbriae, or curli fimbriae, three types of bacterial surface organelles involved in bacterial colonization and invasion. Five microbial peptides with the potential to mimic pSS-related autoepitopes were also enriched in the pSS gut. SLE and pSS shared significant gut microbial traits, including community distribution, altered microbial taxonomy and pathways, and enriched virulence genes. However, Ruminococcus torques was depleted in pSS patients but enriched in SLE patients compared to healthy controls.

CONCLUSIONS

The gut microbiota in treatment-naïve pSS patients was disturbed and shared significant similarity with that in SLE patients.

Application of omics in Sjögren's syndrome

OBJECTIVE

The pathogenesis, diagnosis, and treatment of Sjögren's syndrome (SS) face many challenges, and there is an urgent need to develop new technologies to improve our understanding of SS.

METHODS

By searching the literature published domestically and internationally in the past 20 years, this artical reviewed the research of various omics techniques in SS.

RESULTS

Omics technology provided valuable insights into the pathogenesis, early diagnosis, condition and efficacy evaluation of SS. It is helpful to reveal the pathogenesis of the disease and explore new treatment schemes, which will open a new era for the study of SS.

CONCLUSION

At present, omics research has made some gratifying achievements, but there are still many uncertainties. Therefore, in the future, we should improve research techniques, standardize the collection of samples, and adopt a combination of multi-omics techniques to jointly study the pathogenesis of SS and provide new schemes for its treatment.

Case-Control Study Examining the Composition of the Gut Microbiome in Individuals With and Without Immune-Mediated Dry Eye

PURPOSE

Gut microbiome alterations have been associated with various autoimmune diseases. There are limited data, however, on relationships between gut dysbiosis and immune-related dry eye (DE). Our aim was to compare the gut microbiome composition of individuals with early and late markers of Sjögren syndrome (SS) with controls without DE.

METHODS

We compared 20 individuals with positive early markers [antisalivary protein 1 (SP1), antiparotid secretory protein (PSP), anticarbonic anhydrase 6 (CA6) IgG, IgA, and IgM, n = 19)], or late markers (anti-Ro/SS-A and anti-La/SS-B, n = 1) of SS with no comorbid autoimmune diagnoses and 20 age-matched and sex-matched controls. Collected stool samples underwent deep RNA sequencing. The main outcomes measured included gut microbiome composition and diversity.

RESULTS

A total of 20 cases [Dry Eye Questionnaire-5 15.2 ± 3.4, Ocular Surface Disease Index 55.1 ± 22.8, and Schirmer 7.1 ± 5.2 mm] were compared with 20 controls (Dry Eye Questionnaire-5 4.8 ± 3.8, Ocular Surface Disease Index 14.2 ± 12.3, and Schirmer 20.4 ± 9.2 mm). No differences were observed in α-diversity ( P = 0.97) or overall community structure ( P = 0.62). Between groups, 32 species were differentially abundant ( P < 0.01). Among cases, 27 were relatively more abundant, including 10 Lactobacillus and 4 Bifidobacterium species. A relative depletion of 5 species was found in cases compared with controls, notably Fusobacterium varium and Prevotella stercorea .

CONCLUSIONS

Differences in gut microbiome composition were found in individuals with mostly early markers of SS compared with controls. However, their clinical significance to DE manifestations remains unclear. Further studies are needed to elucidate the role of gut dysbiosis on immune dysregulation and disease activity in the various forms of immune-mediated DE.

Insights into Microbiota in Sjögren's Syndrome

Primary Sjögren's syndrome (pSS) is a heterogeneous chronic autoimmune disorder with multiple clinical manifestations that can develop into non-Hodgkin's lymphoma in mucosa-associated lymphoid tissue. The pathogenesis of Sjögren's syndrome (SS) is not completely understood, but it is assumed that pathogenesis of SS is multifactorial. The microbiota plays a notable role in the development of autoimmune disorders, including Sjögren's syndrome. Molecular mimicry, metabolite changes and epithelial tolerance breakdown are pathways that might help to clarify the potential contribution of the microbiota to SS pathogenesis. This review aims to provide an overview of recent studies describing microbiota changes and microbiota mechanisms associated with Sjögren's syndrome. Data on the microbiota in SS from PubMed, Web of Science, Scopus and the Cochrane Library databases are summarized. Overall, the microbiota makes a major contribution to the development of Sjögren's syndrome and progression. Future microbiota studies should improve the management of this heterogeneous autoimmune disease.

Regulatory T cells: a new therapeutic link for Sjögren syndrome?

Great advancements have been made in understanding the pathogenesis of SS, but there remain unmet needs for effective and targeted treatments. Glandular and extraglandular dysfunction in SS is associated with autoimmune lymphocytic infiltration that invades the epithelial structures of affected organs. Regulatory T (Treg) cells are a subset of CD4+ T lymphocytes that maintain self-tolerance during physiological conditions. Besides inhibiting excessive inflammation and autoimmune response by targeting various immune cell subsets and tissues, Treg cells have also been shown to promote tissue repair and regeneration in pathogenic milieus. The changes of quantity and function of Treg cells in various autoimmune and chronic inflammatory disorders have been reported, owing to their effects on immune regulation. Here we summarize the recent findings from murine models and clinical data about the dysfunction of Treg cells in SS pathogenesis and discuss the therapeutic strategies of direct or indirect targeting of Treg cells in SS. Understanding the current knowledge of Treg cells in the development of SS will be important to elucidate disease pathogenesis and may guide research for successful therapeutic intervention in this disease.

Lessons from Animal Models in Sjögren's Syndrome

Primary Sjögren's syndrome (pSS) is a connective tissue disease characterized by a wide spectrum of clinical features, extending from a benign glandular disease to an aggressive systemic disorder and/or lymphoma. The pathogenesis of Sjögren's syndrome (SS) is not completely understood, but it is assumed that pathogenesis of SS is multifactorial. The studies based on the animal models of SS provided significant insight in SS disease pathogenesis and management. The aim of this review is to summarize current studies on animal models with primary SS-like symptoms and discuss the impact of these studies on better understanding pathogenesis and management of Sjögren's syndrome. Databases PubMed, Web of Science, Scopus and Cochrane library were searched for summarizing studies on animal models in SS. Available data demonstrate that animal models are highly important for our understanding of SS disease.

Lactobacillus acidophilus and propionate attenuate Sjögren's syndrome by modulating the STIM1-STING signaling pathway

BACKGROUND

Sjögren's syndrome (SS) is an autoimmune disease characterized by inflammation of the exocrine gland. An imbalance of gut microbiota has been linked to SS. However, the molecular mechanism is unclear. We investigated the effects of Lactobacillus acidophilus (L. acidophilus) and propionate on the development and progression of SS in mouse model.

METHODS

We compared the gut microbiomes of young and old mice. We administered L. acidophilus and propionate up to 24 weeks. The saliva flow rate and the histopathology of the salivary glands were investigated, and the effects of propionate on the STIM1-STING signaling pathway were evaluated in vitro.

RESULTS

Lactobacillaceae and Lactobacillus were decreased in aged mice. SS symptoms were ameliorated by L. acidophilus. The abundance of propionate-producing bacterial was increased by L. acidophilus. Propionate ameliorated the development and progression of SS by inhibiting the STIM1-STING signaling pathway.

CONCLUSIONS

The findings suggest that Lactobacillus acidophilus and propionate have therapeutic potential for SS. Video Abstract.

Gut microbiota and Sjögren's syndrome: a two-sample Mendelian randomization study

Background

The link between the gut microbiota (GM) and Sjögren's Syndrome (SS) is well-established and apparent. Whether GM is causally associated with SS is uncertain.

Methods

The MiBioGen consortium's biggest available genome-wide association study (GWAS) meta-analysis (n=13,266) was used as the basis for a two-sample Mendelian randomization study (TSMR). The causal relationship between GM and SS was investigated using the inverse variance weighted, MR-Egger, weighted median, weighted model, MR-PRESSO, and simple model methods. In order to measure the heterogeneity of instrumental variables (IVs), Cochran's Q statistics were utilized.

Results

The results showed that genus Fusicatenibacter (odds ratio (OR) = 1.418, 95% confidence interval (CI), 1.072-1.874, P = 0.0143) and genus Ruminiclostridium9 (OR = 1.677, 95% CI, 1.050-2.678, P = 0.0306) were positively correlated with the risk of SS and family Porphyromonadaceae (OR = 0.651, 95% CI, 0.427-0.994, P = 0.0466), genus Subdoligranulum (OR = 0.685, 95% CI, 0.497-0.945, P = 0.0211), genus Butyricicoccus (OR = 0.674, 95% CI, 0.470-0.967, P = 0.0319) and genus Lachnospiraceae (OR = 0.750, 95% CI, 0.585-0.961, P = 0.0229) were negatively correlated with SS risk using the inverse variance weighted (IVW) technique. Furthermore, four GM related genes: ARAP3, NMUR1, TEC and SIRPD were significant causally with SS after FDR correction (FDR<0.05).

Conclusions

This study provides evidence for either positive or negative causal effects of GM composition and its related genes on SS risk. We want to provide novel approaches for continued GM and SS-related research and therapy by elucidating the genetic relationship between GM and SS.

The Spectrum of Extraglandular Manifestations in Primary Sjögren's Syndrome

Extraglandular manifestations (EGMs) in primary Sjogren's syndrome (pSS) represent the clinical expression of the systemic involvement in this disease. EGMs are characterized by a wide heterogeneity; virtually any organ or system can be affected, with various degrees of dysfunction. The existing gaps of knowledge in this complex domain of extraglandular extension in pSS need to be overcome in order to increase the diagnostic accuracy of EGMs in pSS. The timely identification of EGMs, as early as from subclinical stages, can be facilitated using highly specific biomarkers, thus preventing decompensated disease and severe complications. To date, there is no general consensus on the diagnostic criteria for the wide range of extraglandular involvement in pSS, which associates important underdiagnosing of EGMs, subsequent undertreatment and progression to severe organ dysfunction in these patients. This review article presents the most recent basic and clinical science research conducted to investigate pathogenic mechanisms leading to EGMs in pSS patients. In addition, it presents the current diagnostic and treatment recommendations and the trends for future therapeutic strategies based on personalized treatment, as well as the latest research in the field of diagnostic and prognostic biomarkers for extraglandular involvement in pSS.

Exploring the Complex Relationship Between Microbiota and Systemic Lupus Erythematosus

PURPOSE OF REVIEW

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by various autoantibodies and multi-organ. Microbiota dysbiosis in the gut, skin, oral, and other surfaces has a significant impact on SLE development. This article summarizes relevant research and provides new microbiome-related strategies for exploring the mechanisms and treating patients with SLE.

RECENT FINDINGS

SLE patients have disruptions in multiple microbiomes, with the gut microbiota (bacteria, viruses, and fungi) and their metabolites being the most thoroughly researched. This dysbiosis can promote SLE progression through mechanisms such as the leaky gut, molecular mimicry, and epigenetic regulation. Notwithstanding study constraints on the relationship between microbiota and SLE, specific interventions targeting the gut microbiota, such as probiotics, dietary management, and fecal microbiota transplantation, have emerged as promising SLE therapeutics.

Gut dysbiosis in autoimmune diseases: Association with mortality

To better understand the impact of gut dysbiosis on four autoimmune diseases [Sjögren’s syndrome (SS), systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and multiple sclerosis (MS)], this review investigated the altered gut bacteria in each disease and the shared ones among the four diseases. The enriched gut bacteria shared by three of the four autoimmune diseases were Streptococcus, Prevotella, and Eggerthella, which are associated with autoantibody production or activation of Th17 cells in immune-related diseases. On the other hand, Faecalibacterium comprises depleted gut bacteria shared by patients with SLE, MS, and SS, which is associated with various anti-inflammatory activities. The indexes of gut dysbiosis, defined as the number of altered gut bacterial taxa divided by the number of studies in SLE, MS, RA, and SS, were 1.7, 1.8, 0.7, and 1.3, respectively. Interestingly, these values presented a positive correlation trend with the standardized mortality rates —2.66, 2.89, 1.54, and 1.41, respectively. In addition, shared altered gut bacteria among the autoimmune diseases may correlate with the prevalence of polyautoimmunity in patients with SLE, SS, RA, and MS, that is, 41 percent, 32.6 percent, 14 percent, and 1–16.6 percent, respectively. Overall, this review suggests that gut dysbiosis in autoimmune diseases may be closely related to the failure of the gut immune system to maintain homeostasis.

The composition and function profile of the gut microbiota of patients with primary Sjögren's syndrome

OBJECTIVES

This healthy volunteer control-based study was conducted to explore alterations of compositions and function of gut microbiota in Chinese pSS patients.

METHOD

The high-throughput Illumina Miseq sequencing method, targeting the V3-V4 region of the 16S ribosomal RNA (rRNA) gene, was used to compare the microbiota communities between 30 pSS patients and 30 age-matched healthy volunteers. The intestinal dysbiosis of pSS patients was evaluated and its correlation with some disease phenotypes was analyzed. Furthermore, we performed the amino acid sequence alignment analysis to illustrate the molecular mimicry patterns of new microbial peptides.

RESULTS

Compared with that in healthy controls, the composition and function of the gut microbiota significantly differed in pSS patients. Certain genera and species, including genera: Escherichia-Shigella, Sardovia, Veillonella, Insteinimonas, and Lactobacillales; species: Escherichia coli, Lactobacillus phage Sal3, Lactobacillus reuteri, Lactobacillus gasseri, Streptococcus lutetiensis, Streptococcus mutans, Scardovia wiggsiae, and Fusobacterrium ulcerans were found to be enriched in the feces of pSS patients, while butyrate-producing bacteria were less abundant in pSS patients. Certain genera (including Lactobacillales) and species (including Lactobacillus gasseri) were associated with disease severity and therapy resistance parameters. Autoantigen epitopes of "WPSALPT, NPARSFG, MNPARSFG, and AFGLAIGT" from aquaporin-5 were aligned perfectly with one enriched microbiota of patients with pSS, namely Escherichia coli.

CONCLUSIONS

The composition and function of the gut microbiota significantly differed in pSS patients compared with that in healthy controls. Our study would facilitate the possible research on the role of gut microbiota in the pathogenesis of pSS.

Integrated Network Pharmacology and Gut Microbiota Analysis to Explore the Mechanism of Sijunzi Decoction Involved in Alleviating Airway Inflammation in a Mouse Model of Asthma

Background

Asthma is a chronic inflammatory disease of the airways with recurrent attacks, which seriously affects the patients' quality of life and even threatens their lives. The disease can even threaten the lives of patients. Sijunzi decoction (SJZD), a classical Chinese medicine formula with a long history of administration, is a basic formula used for the treatment of asthma and demonstrates remarkable efficacy. However, the underlying mechanism has not been elucidated.

Materials and Methods

We aimed to integrate network pharmacology and intestinal flora sequencing analysis to study the mechanism of SJZD in the treatment of allergic asthmatic mice. The active compounds of SJZD and their asthma-related targets were predicted by various databases. We performed Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses to identify potentially relevant pathways for target genes. Furthermore, the active compound-target and target-signaling pathway network maps were constructed by using Cytoscape 3.8.2. These results were combined with those of the intestinal flora sequencing analysis to study the influence of SJZD on airway inflammation in allergic asthmatic mice.

Result

We obtained 137 active compounds from SJZD and associated them with 1445 asthma-related targets acquired from the databases. A total of 109 common targets were identified. We visualized active compound-target and target-signaling pathway network maps. The pathological analysis and inflammation score results suggested that SJZD could alleviate airway inflammation in asthmatic mice. Sequencing analysis of intestinal flora showed that SJZD could increase the relevant abundance of beneficial bacterial genus and maintain the balance of the intestinal flora. The core toll-like receptor (TLR) signaling pathway was identified based on network pharmacology analysis, and the important role TLRs play in intestinal flora and organismal immunity was also recognized. The analysis of the correlation between environmental factors and intestinal flora revealed that beneficial bacterial genera were negatively correlated with TLR2 and positively correlated with the TLR7 expression. Furthermore, they were positively correlated with IFN-γ and IL-10 levels and negatively correlated with IL-4 and IL-17 levels.

Conclusion

SJZD alleviated the airway inflammation state in asthmatic mice. The findings suggest that increasing the relevant abundance of beneficial intestinal bacteria in mice with asthma, regulating intestinal flora, interfering with the level of TLR2 and TLR7 expression to adjust the secretion of inflammatory factors, and alleviating asthmatic airway inflammation may be the possible mechanism involved in the treatment of asthma by SJZD, providing a basis for further studies on SJZD.

The Gut-Eye Axis: Correlation Between the Gut Microbiota and Autoimmune Dry Eye in Individuals With Sjögren Syndrome

ABSTRACT

The impact of gut microbiota on human health, autoimmunity, and disease occurrence has long been recognized since the advancement of metagenomic sequencing technology has enabled a new level of perspective on the human microbiome. Emerging findings also suggest the existence of a gut-eye axis, wherein gut dysbiosis may be a crucial factor affecting the onset and progression of multiple ocular diseases. Sjögren syndrome (SS) is a chronic autoimmune disease mainly affecting the exocrine glands, primarily the lacrimal gland in the eye, resulting in severe dry eye. Although there are currently various treatments for environmental dry eye, the efficacy for SS-related autoimmune dry eye is limited, and new and more effective therapies still need to be explored. The latest studies have demonstrated that the gut microbiota plays a key role in the pathogenesis of autoimmune dry eye. This review describes the effect of gut microbiota on the ocular surface of autoimmune dry eye; introduces the presumable pathways forming the "gut dysbiosis-ocular surface-lacrimal gland axis"; discusses the advantages of restoring intestinal microecology to treat dry eye by fecal microbiota transplantation or probiotics, which are expected to provide perspectives into the correlation between the gut microbiome and dry eye; enhance our understanding of the pathogenesis in autoimmune dry eye; and be useful in the development of future interventions of dry eye by regulating the gut microbiota.

Hospitalizations for infections in primary Sjögren's syndrome patients: a nationwide incidence study

BACKGROUND

Primary Sjögren's syndrome (pSS) is an autoimmune disease with increased risk of infections. Here, we assessed whether pSS patients were at higher risk of hospitalization for community and opportunistic infections.

METHODS

We selected newly hospitalized pSS patients between 2011 and 2018, through a nationwide population-based retrospective study using the French Health insurance database. We compared the incidence of hospitalization for several types of infections (according to International Classification for Disease codes, ICD-10) between pSS patients and an age- and sex-matched (1:10) hospitalized control group. We calculated adjusted Hazard Ratios (aHR, 95% CI) adjusted on socio-economic status, past cardiovascular or lung diseases and blood malignancies factors.

RESULTS

We compared 25 661 pSS patients with 252 543 matched patients. The incidence of hospitalizations for a first community infection was increased in pSS patients [aHR of 1.29 (1.22-1.31), p < .001]. The incidence of hospitalization for bronchopulmonary infections was increased in pSS patients [aHR of 1.50 (1.34-1.69), p < .001, for pneumonia]. Hospitalizations for pyelonephritis and intestinal infections were increased [aHR of 1.55 (1.29-1.87), p < .001 and 1.18 (1.08-1.29), p < .001, respectively]. Among opportunistic infections, only zoster, and mycobacteria infections (tuberculosis and non-tuberculous) were at increased risk of hospitalization [aHR of 3.32 (1.78-6.18), p < .001; 4.35 (1.41-13.5), p = .011 and 2.54 (1.27-5.06), p = .008, respectively].

CONCLUSIONS

pSS patients are at higher risk of hospitalization for infections. The increased risk of hospitalization for mycobacterial infections illustrates the potential bilateral relationship between the two conditions. Vaccination against respiratory pathogens and herpes zoster virus may help prevent some hospitalizations in pSS patients.KEY MESSAGESPrimary Sjögren's syndrome (pSS) increases hospitalization risk for community infections: bronchopulmonary, skin, dental, ear-nose-throat, intestinal infections and pyelonephritis.Hospitalizations for zoster and mycobacterial infections are also increased in this population.Dedicated preventive measures and vaccination campaigns could decrease the burden of infections in pSS patients.

Compositional and functional aberrance of the gut microbiota in treatment naïve patients with primary Sjögren's syndrome

OBJECTIVES

To investigate the compositional and functional characteristics of the gut microbiota in primary Sjögren's syndrome (pSS) and compare them with those in systemic lupus erythematosus (SLE).

METHODS

Stool samples from 78 treatment naïve pSS patients and 78 matched healthy controls were detected by shotgun metagenomic sequencing and compared with those from 49 treatment naïve SLE patients. The virulence loads and mimotopes of the gut microbiota were also assessed by sequence alignment.

RESULTS

The gut microbiota of treatment naïve pSS patients had lower richness and evenness and showed a different community distribution than that of healthy controls. The microbial species enriched in the pSS-associated gut microbiota included Lactobacillus salivarius, Bacteroides fragilis, Ruminococcus gnavus, Clostridium bartlettii, Clostridium bolteae, Veillonella parvula, and Streptococcus parasanguinis. Lactobacillus salivarius was the most discriminating species in the pSS patients, especially in those with interstitial lung disease (ILD). Among the differentiating microbial pathways, the superpathway of l-phenylalanine biosynthesis was also further enriched in pSS complicated with ILD. There were more virulence genes carried by the gut microbiota in pSS patients, most of which encoded peritrichous flagella, fimbriae, or curli fimbriae, three types of bacterial surface organelles involved in bacterial colonization and invasion. Five microbial peptides with the potential to mimic pSS-related autoepitopes were also enriched in the pSS gut. SLE and pSS shared significant gut microbial traits, including the community distribution, altered microbial taxonomy and pathways, and enriched virulence genes. However, Ruminococcus torques was depleted in pSS patients but enriched in SLE patients compared to that in healthy controls.

CONCLUSIONS

The gut microbiota in treatment naïve pSS patients was disturbed and shared significant similarity with that in SLE patients.

Gastrointestinal microbiome and primary Sjögren's syndrome: a review of the literature and conclusions

The recognition of the profound impact of the human gastrointestinal microbiome (GM) on human autoimmune diseases has gradually increased thanks to deeper research efforts. As a systemic autoimmune disease, primary Sjögren's syndrome (pSS) cannot be completely cured. Human studies have revealed that GM species and diversity are altered in patients with pSS compared with healthy individuals. Animal studies have provided possible mechanisms for the association between pSS and GM. The potential role of GM in pSS is exerted through several mechanisms. GM dysbiosis leads to increased intestinal permeability, which increases the risk of GM antigen exposure and activates specific autoreactive T lymphocytes via "molecular mimicry". In addition, GM antigen exposure and intestinal immune tolerance loss caused by GM dysbiosis together induce chronic local gut mucosal inflammation, which deteriorates to systemic chronic non-specific inflammation with the circulation of pro-inflammatory lymphocytes and cytokines. These factors eventually activate autoreactive B lymphocytes and lead to pSS. If GM plays a key role in the pathogenesis of pSS, clarifying the underlying mechanisms will be helpful for the development of new therapies targeting GM for dry eye associated with pSS. This review summarizes the latest knowledge about the relationship between GM and pSS, with the aim of contributing to future research and to the development of new clinical applications.

Characteristics of gut microbiota in patients with primary Sjögren’s syndrome in Northern China

This study analyzes and compares the structure and diversity of gut microbiota in patients with primary Sjögren’s syndrome (pSS) in Northern China to healthy individuals to identify clinical features associated with dysbiosis. We included 60 Chinese pSS patients and 50 age- and gender-matched healthy controls. DNA was extracted from stool samples and subjected to 16S ribosomal RNA gene analysis (V3-V4) for intestinal dysbiosis. In addition, patients were examined for laboratory and serological pSS features. A Spearman’s correlation analysis was performed to assess correlations between individual bacteria taxa and clinical characteristics. The alpha-diversity (Chao1 and Shannon Index) and beta-diversity (unweighted UniFrac distances) of the gut microbiota differed significantly between pSS patients and healthy controls. Further analysis showed that several gut opportunistic pathogens (Bacteroides, Megamonas, and Veillonella) were significantly more abundant in pSS patients and positively correlated with their clinical indicators. In contrast, some probiotic genera (Collinsella, unidentified_Ruminococcaceae, Romboutsia, and Dorea) were significantly decreased in pSS patients and negatively correlated with their clinical indicators. Therefore, pSS patients in Northern China showed a dysbiotic intestinal microbiome enriched for potentially pathogenic genera that might be associated with autoimmune disease.

Gut Microbiota and Therapy in Metastatic Melanoma: Focus on MAPK Pathway Inhibition

Gut microbiome (GM) and its either pro-tumorigenic or anti-tumorigenic role is intriguing and constitutes an evolving landscape in translational oncology. It has been suggested that these microorganisms may be involved in carcinogenesis, cancer treatment response and resistance, as well as predisposition to adverse effects. In melanoma patients, one of the most immunogenic cancers, immune checkpoint inhibitors (ICI) and MAPK-targeted therapy—BRAF/MEK inhibitors—have revolutionized prognosis, and the study of the microbiome as a modulating factor is thus appealing. Although BRAF/MEK inhibitors constitute one of the main backbones of treatment in melanoma, little is known about their impact on GM and how this might correlate with immune re-induction. On the contrary, ICI and their relationship to GM has become an interesting field of research due to the already-known impact of immunotherapy in modulating the immune system. Immune reprogramming in the tumor microenvironment has been established as one of the main targets of microbiome, since it can induce immunosuppressive phenotypes, promote inflammatory responses or conduct anti-tumor responses. As a result, ongoing clinical trials are evaluating the role of fecal microbiota transplant (FMT), as well as the impact of using dietary supplements, antibiotics and probiotics in the prediction of response to therapy. In this review, we provide an overview of GM’s link to cancer, its relationship with the immune system and how this may impact response to treatments in melanoma patients. We also discuss insights about novel therapeutic approaches including FMT, changes in diet and use of probiotics, prebiotics and symbiotics. Finally, we hypothesize on the possible pathways through which GM may impact anti-tumor efficacy in melanoma patients treated with targeted therapy, an appealing subject of which little is known.

Gut Dysbiosis and Fecal Microbiota Transplantation in Autoimmune Diseases

Gut microbiota dysbiosis has recently been reported in a number of clinical states, including neurological, psychiatric, cardiovascular, metabolic and autoimmune disorders. Yet, it is not completely understood how colonizing microorganisms are implicated in their pathophysiology and molecular pathways. There are a number of suggested mechanisms of how gut microbiota dysbiosis triggers or sustains extraintestinal diseases; however, none of these have been widely accepted as part of the disease pathogenesis. Recent studies have proposed that gut microbiota and its metabolites could play a pivotal role in the modulation of immune system responses and the development of autoimmunity in diseases such as rheumatoid arthritis, multiple sclerosis or type 1 diabetes. Fecal microbiota transplantation (FMT) is a valuable tool for uncovering the role of gut microbiota in the pathological processes. This review aims to summarize the current knowledge about gut microbiota dysbiosis and the potential of FMT in studying the pathogeneses and therapies of autoimmune diseases. Herein, we discuss the extraintestinal autoimmune pathologies with at least one published or ongoing FMT study in human or animal models.

Microbiota dysbiosis in primary Sjögren's syndrome and the ameliorative effect of hydroxychloroquine

The human microbiome plays an important role in autoimmune diseases. However, there is limited knowledge regarding the microbiota in individuals with primary Sjögren's syndrome (pSS). Here, we perform 16S ribosomal RNA gene sequencing of fecal, oral, and vaginal samples from a cohort of 133 individuals with pSS, 56 with non-pSS, and 40 healthy control (HC) individuals. Dysbiosis in the gut, oral, and vaginal microbiome is evident in patients with pSS, and oral samples demonstrate the greatest extent of microbial variation. Multiple key indicator bacteria and clinical characteristics are identified across different body sites, implying that microbial dysbiosis has important roles in the pathogenesis of pSS. Furthermore, we observe pSS-like dysbiosis in individuals with pre-clinical pSS or non-pSS-related disease, revealing that microbial shifts could appear prior to pSS. After hydroxychloroquine (HCQ) treatment, microbial dysbiosis in individuals with pSS is partially resolved, although the microbiota composition remain disordered. These results contribute to the overall understanding of the relationship between the microbiome and pSS.

Depression-like behaviors in mouse model of Sjögren's syndrome: A role of gut-microbiota-brain axis

Depression is a common psychiatric symptom in patients with Sjögren's syndrome (SS). Prevalence of depression in SS patients is significantly higher than that in the general population. Increasing evidence suggests a crucial role of gut-microbiota-brain axis in depression. In this study, we investigated whether non-obese diabetic (NOD) mice, a widely used animal model of SS, exhibit depression-like phenotypes and abnormal composition of gut microbiota. Eleven-week-old NOD mice spontaneously exhibited SS-related symptoms without pancreatic destruction. NOD mice displayed depression-like behaviors, decreased expression of synaptic proteins in the prefrontal cortex (PFC), and abnormal composition of gut microbiota. Interestingly, SS-related proinflammatory factors in the submandibular gland (SMG) and autoantibodies (anti-SSA and anti-SSB) in the plasma were correlated with the expression of synaptic proteins in the PFC or depression-like behaviors. In addition, there were correlations between the relative abundance of microbiota and SS-related symptoms (or depression-related phenotypes). These data suggest that SS-related symptoms and abnormal composition of gut microbiota may play a role in depression-like phenotypes in NOD mice through gut-microbiota-brain axis.

High-fat diet-induced intestinal dysbiosis is associated with the exacerbation of Sjogren’s syndrome

Environmental factors are believed to influence the evolution of primary Sjögren’s syndrome (pSS). The aims of this study were to investigate the association of pSS with a high-fat diet (HFD) and to relate HFD-induced gut dysbiosis to pSS exacerbation. Male Wild Type (WT) and IL-14α transgenic mice (IL-14α TG) were fed a standard diet (SD) and HFD for 11 months. We found an increase in the autoantibody level, more severe dry eye, severe dry mouth symptoms, and an earlier presence of systemic features in the IL-14α TG mice treated with HFD. These data suggest that HFD can promote the process of pSS in the IL-14α TG mice. In addition, an HFD leads to a decrease in the richness of gut microbiota of IL-14α TG mice treated with HFD. The abundance of Deferribacterota was significantly enriched in the IL-14α TG mice treated with HFD compared with other groups. Through the mental test between gut microbiota and clinical parameters, we found that HFD-induced dysbiosis gut microbiota were associated with pSS clinical parameters. In conclusion, HFD results in the aggravation of pSS progression, likely due to the increase of potentially pathogenic microorganisms.

A Glimpse Into the Microbiome of Sjögren’s Syndrome

Sjögren’s syndrome (SS) is a common chronic systemic autoimmune disease and its main characteristic is lymphoid infiltration of the exocrine glands, particularly the salivary and lacrimal glands, leading to sicca symptoms of the mouth and eyes. Growing evidence has shown that SS is also characterized by microbial perturbations like other autoimmune diseases. Significant alterations in diversity, composition, and function of the microbiota were observed in SS. The dysbiosis of the microbiome correlates with worse symptoms and higher disease severity, suggesting that dysbiosis may be of great importance in the pathogenesis of SS. In this review, we provide a general view of recent studies describing the microbiota alterations of SS, the possible pathways that may cause microbiota dysbiosis to trigger SS, and the existence of the gut-ocular/gut-oral axis in SS.

Microbiome and immune-mediated dry eye: a review

In this review, we aim to summarise key articles that explore relationships between the gut and ocular surface microbiomes (OSMs) and immune-mediated dry eye. The gut microbiome has been linked to the immune system by way of stimulating or mitigating a proinflammatory or anti-inflammatory lymphocyte response, which may play a role in the severity of autoimmune diseases. Although the 'normal' gut microbiome varies among individuals and demographics, certain autoimmune diseases have been associated with characteristic gut microbiome changes. Less information is available on relationships between the OSM and dry eye. However, microbiome manipulation in multiple compartments has emerged as a therapeutic strategy, via diet, prebiotics and probiotics and faecal microbial transplant, in individuals with various autoimmune diseases, including immune-mediated dry eye.

Gut Dysbiosis in Ocular Mucous Membrane Pemphigoid

Mucous Membrane Pemphigoid is an orphan multi-system autoimmune scarring disease involving mucosal sites, including the ocular surface (OcMMP) and gut. Loss of tolerance to epithelial basement membrane proteins and generation of autoreactive T cell and/or autoantibodies are central to the disease process. The gut microbiome plays a critical role in the development of the immune system. Alteration in the gut microbiome (gut dysbiosis) affects the generation of autoreactive T cells and B cell autoantibody repertoire in several autoimmune conditions. This study examines the relationship between gut microbiome diversity and ocular inflammation in patients with OcMMP by comparing OcMMP gut microbiome profiles with healthy controls. DNA was extracted from faecal samples (49 OcMMP patients, 40 healthy controls), amplified for the V4 region of the 16S rRNA gene and sequenced using Illumina Miseq platform. Sequencing reads were processed using the bioinformatics pipeline available in the mothur v.1.44.1 software. After adjusting for participant factors in the multivariable model (age, gender, BMI, diet, proton pump inhibitor use), OcMMP cohort was found to be associated with lower number of operational taxonomic units (OTUs) and Shannon Diversity Index when compared to healthy controls. Within the OcMMP cohort, the number of OTUs were found to be significantly correlated with both the bulbar conjunctival inflammation score (p=0.03) and the current use of systemic immunotherapy (p=0.02). The linear discriminant analysis effect size scores indicated that Streptococcus and Lachnoclostridium were enriched in OcMMP patients whilst Oxalobacter, Clostridia uncultured genus-level group (UCG) 014, Christensenellaceae R-7 group and butyrate-producing bacteria such as Ruminococcus, Lachnospiraceae, Coprococcus, Roseburia, Oscillospiraceae UCG 003, 005, NK4A214 group were enriched in healthy controls (Log10 LDA score < 2, FDR-adjusted p <0.05). In conclusion, OcMMP patients have gut dysbiosis correlating with bulbar conjunctival inflammation and the use of systemic immunotherapies. This provides a framework for future longitudinal deep phenotyping studies on the role of the gut microbiome in the pathogenesis of OcMMP.

Integrated Network Pharmacology and Mice Model to Investigate Qing Zao Fang for Treating Sjögren's Syndrome

Sjögren's syndrome (SS) is an autoimmune disease, and its conventional treatment has exhibited limited therapeutic efficacy. Qing Zao Fang (QZF), a traditional Chinese medicine formula, is used in the treatment of Sjögren's syndrome, but its chemical composition is complex, and its pharmacological mechanism is not clear. Therefore, this study aims to explore the potential mechanism of QZF in the treatment of Sjögren's syndrome based on network pharmacology and SS mouse model. The main active components and predicted targets of QZF were analyzed by network pharmacology. The SS mouse model was constructed and divided into 6 groups: control, SS, SS + hydroxychloroquine (HCQ)-treated, SS + low-dose QZF-treated, SS + medium-dose QZF-treated, and SS + high-dose QZF-treated group. Immunohistochemical, ELISA, and qRT-PCR assays were performed to detect the expressions of targets associated with SS. TUNEL staining was used to detect apoptosis. Cumulatively, 230 active compounds and 1883 targets of QZF were identified. There were 227 common targets for QZF and SS. The effective active ingredients were stigmasterol, neocryptotanshinone II, neotanshinone C, miltionone I, and beta-pinene. It mainly acts on biological processes such as inflammatory response, chemokine metabolic process, and immune response as well as pathways such as FoxO signaling pathway, Yersinia infection, HIF-1 signaling pathway, and TNF signaling pathway. In SS mice, levels of AKT1, HIF-1α, TNF-α, IL-6, and IL-17A were increased, while decreased after QZF treatment. In contrast, IL-10 levels were decreased in SS mice and increased in QZF-treated mice. In addition, QZF reduced apoptosis in the submandibular gland tissue compared to SS mice. It can be concluded that the QZF in treatment of SS is the result of the combined action of multiple components, multiple targets, and multiple pathways. This study improves the understanding of the link between QZF and SS on molecular mechanisms.

Aquaporin5-Targeted Treatment for Dry Eye Through Bioactive Compounds and Gut Microbiota

Dry eye and dry mouth are the principal sources of morbidity for patients with Sjögren's syndrome (SS). There are few effective treatments, particularly systemic ones. Targeting aquaprin-5 (AQP5)-mediated tear secretion has been tested as a novel ancillary strategy and has proved promising. Patients have a great interest in using complementary medicine, including nutraceuticals and bioactive compounds to alleviate their symptoms. Potential mechanisms by which phytocompounds and bioactive compounds may benefit SS ocular and mouth symptoms through modulation of AQP5 activity are presented within this review. Supplementation with prebiotics (such as polyphenols with high bioavailability) in SS patients with lower Firmicutes/Bacteroides (F/B) community ratio phenotype, through administration of butyrate-producing diets, is proposed as ancillary strategy for dry eye and mouth. The potential use of natural bioactive compounds to treat dry eye could also apply to dry mouth occurring in the context of aging and SS. This novel hypothesis could have implications with respect to planning a successful dietary regimen for achieving and maintaining a normal gut microbiota in SS patients. This regimen would include augmenting butyrate-producing foodstuffs and/or polyphenol-rich syrups, and high amounts of some specific probiotic-rich foodstuffs such as yogurt, soy yogurt, or as probiotic supplements. There are applications for pharmaceutical and nutraceutical products aiming to relieve dry eye and mouth.

Exploring the Oral Microbiome in Rheumatic Diseases, State of Art and Future Prospective in Personalized Medicine with an AI Approach

The oral microbiome is receiving growing interest from the scientific community, as the mouth is the gateway for numerous potential etiopathogenetic factors in different diseases. In addition, the progression of niches from the mouth to the gut, defined as "oral-gut microbiome axis", affects several pathologies, as rheumatic diseases. Notably, rheumatic disorders (RDs) are conditions causing chronic, often intermittent pain affecting the joints or connective tissue. In this review, we examine evidence which supports a role for the oral microbiome in the etiology and progression of various RDs, including rheumatoid arthritis (RA), Sjogren's syndrome (SS), and systemic lupus erythematosus (SLE). In addition, we address the most recent studies endorsing the oral microbiome as promising diagnostic biomarkers for RDs. Lastly, we introduce the concepts of artificial intelligence (AI), in particular, machine learning (ML) and their general application for understanding the link between oral microbiota and rheumatic diseases, speculating the application of a possible AI approach-based that can be applied to personalized medicine in the future.

Dysbiosis of gut microbiota and its correlation with dysregulation of cytokines in psoriasis patients

Background

Psoriasis is an inflammatory skin disease associated with multiple comorbidities and substantially diminishes patients’ quality of life. The gut microbiome has become a hot topic in psoriasis as it has been shown to affect both allergy and autoimmunity diseases in recent studies. Our objective was to identify differences in the fecal microbial composition of patients with psoriasis compared with healthy individuals to unravel the microbiota profiling in this autoimmune disease.

Results

We collected fecal samples from 30 psoriasis patients and 30 healthy controls, sequenced them by 16S rRNA high-throughput sequencing, and identified the gut microbial composition using bioinformatic analyses including Quantitative Insights into Microbial Ecology (QIIME) and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt). Our results showed that different relative abundance of certain bacterial taxa between psoriasis patients and healthy individuals, including Faecalibacterium and Megamonas, were increased in patients with psoriasis. It’s also implicated that many cytokines act as main effect molecules in the pathology of psoriasis. We selected the inflammation-related indicators that were abnormal in psoriasis patients and found the microbiome variations were associated with the level of them, especially interleukin-2 receptor showed a positive relationship with Phascolarctobacterium and a negative relationship with the Dialister. The relative abundance of Phascolarctobacterium and Dialister can be regard as predictors of psoriasis activity. The correlation analysis based on microbiota and Inflammation-related indicators showed that microbiota dysbiosis might induce an abnormal immune response in psoriasis.

Conclusions

We concluded that the gut microbiome composition in psoriasis patients has been altered markedly and provides evidence to understand the relationship between gut microbiota and psoriasis. More mechanistic experiments are needed to determine whether the differences observed in gut microbiota are the cause or consequences of psoriasis and whether the relationship between gut microbiota and cytokines was involved.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02125-1.