T Helper 17 Cells in Primary Sjögren's Syndrome

Genetic insight into dissecting the immunophenotypes and inflammatory profiles in the pathogenesis of Sjogren syndrome

BACKGROUND

Sjogren syndrome (SS) is a chronic systemic autoimmune disease and its pathogenesis often involves the participation of numerous immune cells and inflammatory factors. Despite increased researches and studies recently focusing on this area, it remains to be fully elucidated. We decide to incorporate genetic insight into investigation of the causal link between various immune cells, inflammatory factors and pathogenesis of Sjogren syndrome (SS).

METHODS

Our study leveraged the genetic variants of multi-omics statistics extracted from genome-wide association study (GWAS), the University of Bristol and the FinnGen study. We performed a bidirectional Mendelian randomization and mediation study based on randomly allocated instrumental variables to infer causality, followed by external validation with UK Biobank data and Bayesian colocalization.

RESULTS

We demonstrated that an elevated level of CD27 on IgD + CD24 + B cell, a subset of B cells expressing both IgD and CD24, was associated with a higher risk of SS (OR = 1.119, 95% CI: 1.061-1.179, P < 0.001), while CD3 on CD45RA + CD4 + Treg was a protective factor (OR = 0.917, 95%CI: 0.877-0.959, P < 0.001). Results of meta-analysis and colocalization further supported the significant results identified in the primary analysis. A total of 4 inflammatory cytokines and 7 circulating proteins exhibited potential causal relationships with SS despite no significant result achieved after FDR correction. Finally, results of mediation analysis indicated that CD40L receptor levels had significant mediating effects (β = 0.0314, 95% CI: 0.0004-0.0624, P = 0.0471) at a mediation proportion of 28% (95% CI: 0.364%-55.6%) in causal relationship between CD27 on IgD + CD24 + B cell and SS.

CONCLUSIONS

By providing a novel genetic insight into unveiling the roles of autoimmunity and inflammation in Sjogren syndrome, our findings may potentially lead to identifying new clinical biomarkers for disease monitoring and therapeutic targets that offer more effective alternatives for treating this condition. Therefore, our study may provide valuable evidence for future clinical intervention and targeted immunotherapy.

Endogenous IL-22 contributes to the pathogenesis of salivary gland dysfunction in the non-obese diabetic model of Sjögren's syndrome

Sjӧgren's syndrome is a systemic autoimmune disease primarily targeting the salivary and lacrimal glands. Our previous investigations have shown that administration of interleukin-22 (IL-22), an IL-10 family cytokine known for its complex and context-dependent effects on tissues, either protective- or detrimental, to salivary glands leads to hypofunction and pathological changes of salivary glands in C57BL/6 mice and in non-obese diabetic (NOD) mice, the latter being a commonly used model of Sjӧgren's syndrome. This study aims to delineate the pathophysiological roles of endogenously produced IL-22 in the development of salivary gland pathologies and dysfunction associated with Sjӧgren's disease in the NOD mouse model. Our results reveal that neutralizing IL-22 offered a protective effect on salivary gland function without significantly affecting the immune cell infiltration of salivary glands or the autoantibody production. Blockade of IL-22 reduced the levels of phosphorylated STAT3 in salivary gland tissues of NOD mice, while its administration to salivary glands had the opposite effect. Correspondingly, the detrimental impact of exogenously applied IL-22 on salivary glands was almost completely abrogated by a specific STAT3 inhibitor. Moreover, IL-22 blockade led to a downregulation of protein amounts of Ten-Eleven-Translocation 2, a methylcytosine dioxygenase critical for mediating interferon-induced responses, in salivary gland epithelial cells. IL-22 neutralization also exerted a protective effect on the salivary gland epithelial cells that express high levels of surface EpCAM and bear the stem cell potential, and IL-22 treatment in vitro hampered the survival/expansion of these salivary gland stem cells, indicating a direct negative impact of IL-22 on these cells. In summary, this study has uncovered a critical pathogenic role of the endogenous IL-22 in the pathogenesis of Sjögren's disease-characteristic salivary gland dysfunction and provided initial evidence that this effect is dependent on STAT3 activation and potentially achieved through fostering Tet2-mediated interferon responses in salivary gland epithelial cells and negatively affecting the EpCAMhigh salivary gland stem cells.

Risk factors of primary Sjögrens syndrome combined with osteoporosis

Primary Sjögren's syndrome (pSS) is a systemic autoimmune disease that is prevalent in middle-aged and elderly women, characterized by dry mouth, dry eyes, fatigue, and joint pain. Nearly one-third pSS patients have been suffering with osteoporosis (OP), displaying symptoms of lumbago, back pain, and even fracture, all of which severely affect their life quality. Common risk factors for pSS and OP include gender and age, persistent state of inflammation, immune disorders, intestinal flora imbalance, vitamin D deficiency, dyslipidemia and sarcopenia. Meanwhile, the comorbidities of pSS, such as renal tubular acidosis, primary biliary cholangitis, autoimmune thyroid diseases, and drugs (glucocorticoids, methotrexate, and cyclophosphamide) are unique risk factors for pSS complicated with OP. Education, guidance of healthy lifestyle, and OP screening are recommended for bone management of pSS patients. Early detection and intervention are crucial for keeping bone health and life quality in pSS patients.

The role of epithelial cells in the immunopathogenesis of Sjögren's syndrome

Sjögren's syndrome is a systemic autoimmune disease characterized by dysfunction of the affected exocrine glands. Lymphocytic infiltration within the inflamed glands and aberrant B-cell hyperactivation are the two salient pathologic features in Sjögren's syndrome. Increasing evidence indicates that salivary gland epithelial cells act as a key regulator in the pathogenesis of Sjögren's syndrome, as revealed by the dysregulated innate immune signaling pathways in salivary gland epithelium and increased expression of various proinflammatory molecules as well as their interaction with immune cells. In addition, salivary gland epithelial cells can regulate adaptive immune responses as nonprofessional antigen-presenting cells and promote the activation and differentiation of infiltrated immune cells. Moreover, the local inflammatory milieu can modulate the survival of salivary gland epithelial cells, leading to enhanced apoptosis and pyroptosis with the release of intracellular autoantigens, which further contributes to SG autoimmune inflammation and tissue destruction in Sjögren's syndrome. Herein, we reviewed recent advances in elucidating the role of salivary gland epithelial cells in the pathogenesis of Sjögren's syndrome, which may provide rationales for potential therapeutic targeting of salivary gland epithelial cells to alleviate salivary gland dysfunction alongside treatments with immunosuppressive reagents in Sjögren's syndrome.

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.

Endocrine-disrupting chemicals and autoimmune diseases

Endocrine-disrupting chemicals (EDCs) widely exist in people's production and life which have great potential to damage human and animal health. Over the past few decades, growing attention has been paid to the impact of EDCs on human health, as well as immune system. So far, researchers have proved that EDCs (such as bisphenol A (BPA), phthalate, tetrachlorodibenzodioxin (TCDD), etc.) affect human immune function and promotes the occurrence and development of autoimmune diseases (ADs). Therefore, in order to better understand how EDCs affect ADs, we summarized the current knowledge about the impact of EDCs on ADs, and elaborated the potential mechanism of the impact of EDCs on ADs in this review.

A multi-center, open-label, randomized study to explore efficacy and safety of baricitinib in active primary Sjogren's syndrome patients

BACKGROUND

Primary Sjogren's syndrome (pSS) is a systemic autoimmune disease involving multiple organ systems. The Janus kinase/signal transduction and activator of transcription (JAK/STAT) signaling pathway is a key pathway involving the pathogenesis of pSS. Baricitinib, a selective JAK1 and JAK2 inhibitor, has been approved for treatment of active rheumatoid arthritis and reported in treatment of some other autoimmune diseases including systemic lupus erythematosus. We have found that baricitinib might be effective and safe in pSS in a pilot study. However, there is no published clinical evidence of baricitinib in pSS. Hence, we conducted this randomized study to further explore the efficacy and safety of baricitinib in pSS.

METHODS

This is a multi-center, prospective, open-label, randomized study to compare the efficacy of baricitinib + hydroxychloroquine (HCQ) with HCQ alone in pSS patients. We plan to involve 87 active pSS patients with European League Against Rheumatism pSS disease activity index (ESSDAI) ≥ 5 from eight different tertiary centers in China. Patients will be randomized (2:1) to receive baricitinib 4 mg per day + HCQ 400 mg per day or HCQ 400 mg per day alone. We will switch HCQ to baricitinib + HCQ if the patient in the latter group has no ESSDAI response at week 12. The final evaluation will be at week 24. The primary endpoint is the percentage of ESSDAI response, or minimal clinically important improvement (MCII), which was defined as an improvement of ESSDAI at least three points at week 12. The secondary endpoints include EULAR pSS patient-reported index (ESSPRI) response, change of Physician's Global Assessment (PGA) score, serological activity parameters, salivary gland function test, and focus score on labial salivary gland biopsy.

DISCUSSION

This is the first randomized controlled study to evaluate the clinical efficacy and safety of baricitinib in pSS. We hope that the result of this study can provide more reliable evidence of the efficacy and safety of baricitinib in pSS.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05016297. Registered on 19 Aug 2021.

Interleukin-22 Exerts Detrimental Effects on Salivary Gland Integrity and Function

Interleukin-22 (IL-22) affects epithelial tissue function and integrity in a context-dependent manner. IL-22 levels are elevated in salivary glands of Sjögren’s syndrome (SS) patients, but its role in the pathogenesis of this disease remains unclear. The objective of this study is to elucidate the impact of IL-22 on salivary gland tissue integrity and function in murine models. We showed that IL-22 levels in sera and salivary glands increased progressively in female non-obese diabetic (NOD) mice, accompanying the development of SS. Administration of IL-22 to the submandibular glands of NOD mice prior to the disease onset reduced salivary secretion and induced caspase-3 activation in salivary gland tissues, which were accompanied by alterations in multiple genes controlling tissue integrity and inflammation. Similarly, IL-22 administration to submandibular glands of C57BL/6 mice also induced hyposalivation and caspase-3 activation, whereas blockade of endogenous IL-22 in C57BL/6 mice treated with anti-CD3 antibody mitigated hyposalivation and caspase-3 activation. Finally, IL-22 treatment reduced the number of viable C57BL/6 mouse submandibular gland epithelial cells cultured in vitro, indicating a direct impact of this cytokine on these cells. We conclude that IL-22 exerts a detrimental impact on salivary gland tissues.

Salivary gland function, development, and regeneration

Salivary glands produce and secrete saliva, which is essential for maintaining oral health and overall health. Understanding both the unique structure and physiological function of salivary glands, as well as how they are affected by disease and injury, will direct the development of therapy to repair and regenerate them. Significant recent advances, particularly in the OMICS field, increase our understanding of how salivary glands develop at the cellular, molecular, and genetic levels: the signaling pathways involved, the dynamics of progenitor cell lineages in development, homeostasis, and regeneration, and the role of the extracellular matrix microenvironment. These provide a template for cell and gene therapies as well as bioengineering approaches to repair or regenerate salivary function.

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.

Qing Zao Fang (QZF) Alleviates the Inflammatory Microenvironment of the Submandibular Gland in Sjögren's Syndrome Based on the PI3K/Akt/HIF-1α/VEGF Signaling Pathway

Sjögren's syndrome (SS) which could lead to a disorder of our immune system is a chronic autoimmune disease characterized by invading exocrine glands such as salivary glands and lacrimal glands and other exocrine glands. Its common symptom is dry mouth and dry eyes, often accompanied by a large number of lymphocyte infiltrations and can involve other organs to cause complex clinical manifestations. In this study, we aimed at investigating the effect of QZF in SS, identifying the molecular mechanism in modulating autoimmune response, and determining the important roles of these factors' function as a modulator in the pathogenesis of SS. The NOD mice were utilized to establish the rats' model of Sjögren's syndrome. After 10 weeks' hydroxychloroquine and QZF in different dose interference, submandibular gland tissue was collected. The therapeutic effect of QZF on SS rats was identified, and the results suggest the comparable potential to hydroxychloroquine. In submandibular gland tissue, interleukin- (IL-) 17 was significantly lower in high-dose QZF than that in SS rats and the focal lymphocytes were highly attenuated. Moreover, we found that PI3K/Akt signals were activated and the downstream HIF-1α/VEGF signals were enhanced in SS rats whose protein expression could be inhibited by QZF treatment. In addition, QZF could modulate autophagy in submandibular gland tissue and then inhibit the inflammation response and therefore facilitate the tissue repair.

Anti-Ro/SSA and/or anti-La/SSB antibodies are associated with adverse IVF and pregnancy outcomes

Anti-Ro/SSA and/or anti-La/SSB antibodies (anti-SSA/SSB) were reported to increase the risk of recurrent pregnancy loss. However, the effects of anti-SSA/SSB antibodies on in-vitro fertilization (IVF) and pregnancy outcomes were still unclear. The purpose of the study was to determine whether anti-SSA/SSB antibodies were detrimental to IVF and pregnancy outcomes. This study included 55 anti-SSA/SSB antibodies-positive women and 61 anti-SSA/SSB antibodies-negative control women receiving gonadotropin-releasing hormone (GnRH) agonist long protocol (n = 30 and 39, respectively) or GnRH antagonist protocol (n = 25 and 22, respectively) for in-vitro fertilization and embryo transfer (IVF-ET). The impact of anti-SSA/SSB antibodies on immune-related indicators, fertilization, embryo development and pregnancy outcomes were analyzed. With either GnRH agonist or antagonist protocol, women with anti-SSA/SSB had higher levels of peripheral blood cytokines, including TNF-α and IL-17A, lower levels of peripheral blood Th and NK cells, and poor IVF outcomes, including lower number of retrieved oocytes and embryos, lower M II oocytes rate, blastocyst formation rate, and perfect and available embryo rates. Moreover, clinical pregnancy rate, implantation rate, take-home baby rate, and birth weight were significantly lower in the study group as compared with those of the control group. In conclusion, women with anti-SSA/SSB are associated with adverse IVF and pregnancy outcomes. Screening for these antibodies and proper counselling of couples undergoing IVF-ET should be considered. Underlying immunopathology associated with SSA/SSB antibodies and reproduction should be explored further.

Stem cells from exfoliated deciduous teeth transplantation ameliorates Sjögren's syndrome by secreting soluble PD-L1

Mesenchymal stem cell transplantation (MSCT) regulates immune cells, and is a promising therapeutic approach for treating autoimmune diseases. Stem cells from human exfoliated deciduous teeth (SHED) are a unique postnatal stem cell population from the cranial neural crest with high self-renewal, multipotent differentiation, and superior immunomodulatory properties. However, the mechanisms by which SHED can treat autoimmune diseases remain unclear. Sjögren's syndrome (SS) is an autoimmune disease histologically characterized by high lymphocytic infiltration in the salivary and lacrimal glands that results in dryness symptoms. This study explores the potential of systemic transplantation of SHED to ameliorate SS-induced dryness symptoms in mice. Overall, SHED could rescue the balance of regulatory T cell (Treg)/T helper cell 17 (Th17) in the recipient SS mice. Mechanistically, SHED promoted Treg conversion and inhibited Th17 function via paracrine effects, which were related to the secretion of soluble programmed cell death ligand 1 (sPD-L1). Moreover, it directly induced Th17 apoptosis via cell-cell contact, leading to the up-regulation of Treg and down-regulation of Th17 cells. In summary, SHED-mediated rescue of Treg/Th17 balance via the sPD-L1/PD-1 pathway ameliorates the gland inflammation and dryness symptoms in SS mice. These findings suggest that SHED are a promising stem cell source for the treatment of autoimmune diseases in the clinical setting.

Immunobiology of T Cells in Sjögren's Syndrome

Sjögren's syndrome (SjS) is a systemic autoimmune disease marked by xerostomia (dry mouth), keratoconjunctivitis sicca (eye dryness), and other systematic disorders. Its pathogenesis involves an inflammatory process that is characterized by lymphocytic infiltration into exocrine glands and other tissues. Although the development of ectopic lymphoid tissue and overproduction of autoantibodies by hyperactive B cells suggest that they may promote SjS development, treatment directed towards them fails to induce significant laboratory or clinical improvement. T cells are overwhelming infiltrators in most phases of the disease, and the involvement of multiple T cell subsets of suggests the extraordinary complexity of SjS pathogenesis. The factors, including various cellular subtypes and molecules, regulate the activation and suppression of T cells. T cell activation induces inflammatory cell infiltration, B cell activation, tissue damage, and metabolic changes in SjS. Knowledge of the pathways that link these T cell subtypes and regulation of their activities are not completely understood. This review comprehensively summarizes the research progress and our understanding of T cells in SjS, including CD4⁺ T cells, CD8⁺ T_RM cells, and innate T cells, to provide insights into for clinical treatment.

IL-17 and CCR9+α4β7- Th17 Cells Promote Salivary Gland Inflammation, Dysfunction, and Cell Death in Sjögren's Syndrome

Previous studies have evaluated the roles of T and B cells in the pathogenesis of Sjögren's syndrome (SS); however, their relationships with age-dependent and metabolic abnormalities remain unclear. We examined the impacts of changes associated with aging or metabolic abnormalities on populations of T and B cells and SS disease severity. We detected increased populations of IL-17-producing T and B cells, which regulate inflammation, in the salivary glands of NOD/ShiLtJ mice. Inflammation-induced human submandibular gland cell death, determined based on p-MLKL and RIPK3 expression levels, was significantly increased by IL-17 treatment. Among IL-17-expressing cells in the salivary gland, peripheral blood, and spleen, the α4β7 (gut-homing integrin)-negative population was significantly increased in aged NOD/ShiLtJ mice. The α4β7-positive population markedly increased in the intestines of aged NOD/ShiLtJ mice following retinoic acid (RA) treatment. A significant increase in α4β7-negative IL-17-expressing cells in salivary glands may be involved in the onset and progression of SS. These results suggest the potential therapeutic utility of RA in SS treatment.

Sex Differences in Otolaryngology: Focus on the Emerging Role of Estrogens in Inflammatory and Pro-Resolving Responses

Otolaryngology (also known as ear, nose, and throat (ENT)) diseases can be significantly affected by the level of sex hormones, which indicates that sex differences affect the manifestation, pathophysiology, and outcomes of these diseases. Recently, increasing evidence has suggested that proinflammatory responses in ENT diseases are linked to the level of sex hormones. The sex hormone receptors are present on a wide variety of immune cells; therefore, it is evident that they play crucial roles in regulating the immune system and hence affect the disease progression of ENT diseases. In this review, we focus on how sex hormones, particularly estrogens, regulate ENT diseases, such as chronic rhinosinusitis, vocal fold polyps, thyroid cancer, Sjögren’s syndrome, and head and neck cancers, from the perspectives of inflammatory responses and specialized proresolving mediator-driven resolution. This paper aims to clarify why considering sex differences in the field of basic and medical research on otolaryngology is a key component to successful therapy for both males and females in the future.

Adaptive Immune Responses Associated with the Central Nervous System Pathology of Gulf War Illness

Gulf War Illness is a multisymptomatic condition which affects 30% of veterans from the 1991 Gulf War. While there is evidence for a role of peripheral cellular and humoral adaptive immune responses in Gulf War Illness, a potential role of the adaptive immune system in the central nervous system pathology of this condition remains unknown. Furthermore, many of the clinical features of Gulf War Illness resembles those of autoimmune diseases, but the biological processes are likely different as the etiology of Gulf War Illness is linked to hazardous chemical exposures specific to the Gulf War theatre. This review discusses Gulf War chemical–induced maladaptive immune responses and a potential role of cellular and humoral immune responses that may be relevant to the central nervous system symptoms and pathology of Gulf War Illness. The discussion may stimulate investigations into adaptive immunity for developing novel therapies for Gulf War Illness.

Triptolide reduces salivary gland damage in a non-obese diabetic mice model of Sjögren's syndrome via JAK/STAT and NF-κB signaling pathways

Triptolide (TP) has anti-inflammatory and immunosuppressive effects. However, the effect of triptolide on Sjögren's syndrome (SS) is rarely reported. In this paper, we studied the effects of triptolide on non-obese diabetes mice model of SS. In this study, salivary flow rate was measured every two weeks, and autoantibodies levels in the serum were detected. Salivary gland index and spleen index were detected, pathological changes of salivary gland were detected by hematoxylin-eosin staining, inflammatory factors were detected by enzyme linked immunosorbent assay, lymphocytes were detected by flow cytometry, proliferation of T cells and B cells were detected, and related proteins were detected by Western blot. Triptolide increased salivary flow rate and salivary gland index, and decreased spleen gland index. Moreover, triptolide reduced the infiltration of lymphocytes to salivary glands, decreased the level of autoantibodies in serum, and reduced the inflammatory factors in salivary glands and IFN-γ induced salivary gland epithelial cells. Further, triptolide inhibited activator of JAK/STAT pathway and NF-κB pathway. In conclusion, triptolide could inhibit the infiltration of lymphocytes and the expression of inflammatory factors through JAK/STAT pathway and NF-κB pathway. Thus, triptolide may be used as a potential drug to treat SS.

The therapeutic applications of mesenchymal stromal cells from human perinatal tissues in autoimmune diseases

The autoimmune diseases are characterized by overactivation of immune cells, chronic inflammation, and immune response to self-antigens, leading to the damage and dysfunction of multiple organs. Patients still do not receive desired clinical outcomes while suffer from various adverse effects imparted by current therapies. The therapeutic strategies based on mesenchymal stromal cell (MSC) transplantation have become the promising approach for the treatment of autoimmune diseases due to the immunomodulation property of MSCs. MSCs derived from perinatal tissues are collectively known as perinatal MSCs (PMSCs), which can be obtained via painless procedures from donors with lower risk of being contaminated by viruses than those MSCs from adult tissue sources. Therefore, PMSCs may be the ideal cell source for the treatment of autoimmune diseases. This article summarizes recent progress and possible mechanisms of PMSCs in treating autoimmune diseases in animal experiments and clinical studies. This review also presents existing challenges and proposes solutions, which may provide new hints on PMSC transplantation as a therapeutic strategy for the treatment of autoimmune diseases.

Interleukin-22 and connective tissue diseases: emerging role in pathogenesis and therapy

Interleukin-22 (IL-22), a member of the IL-10 family of cytokines, is produced by a number of immune cells involved in the immune microenvironment of the body. IL-22 plays its pivotal roles by binding to the IL-22 receptor complex (IL-22R) and subsequently activating the IL-22R downstream signalling pathway. It has recently been reported that IL-22 also contributes to the pathogenesis of many connective tissue diseases (CTDs). In this review, we will discuss the role of IL-22 in several CTDs, such as system lupus erythematosus, rheumatoid arthritis, Sjögren’s syndrome, systemic sclerosis and dermatomyositis, suggesting that IL-22 may be a potential therapeutic target in CTDs.

Transcriptome Sequencing Reveals Potential Roles of ICOS in Primary Sjögren's Syndrome

Primary Sjögren's syndrome (pSS) is a chronic systemic autoimmune disease characterized by exocrine gland damage and extraglandular involvements. To identify potential biomarkers for the early detection of pSS and to further investigate the potential roles of the biomarkers in the progression of pSS, our previous RNA sequencing data and four microarray data of salivary glands (SGs) were combined for integrative transcriptome analysis between pSS and non-pSS. Differential gene expression analysis, gene co-expression network analysis, and pathway analysis were conducted to detect hub genes, which were subsequently investigated in peripheral blood mononuclear cell (PBMC) and plasma. Correlation analysis, single-gene Gene Set Enrichment Analysis, and receiver operating characteristic (ROC) curve were applied to investigate the potential function of the hub genes and their classification capacity for pSS. A total of 51 common up-regulated genes were identified among different pSS cohorts. A key module was found to be the most closely linked to pSS, which was significantly associated with inflammation-related pathways. Seven overlapped hub genes (ICOS, SELL, CR2, BANK1, MS4A1, ZC3H12D, and CCR7) were identified, among which ICOS was demonstrated to be involved in most crucial immune pathways. ICOS was up-regulated not only in SGs but also in PBMC and plasma in pSS, and the expression of ICOS was closely associated with lymphocytic infiltration in SGs and disease activity of pSS patients. It showed a strong classification capacity with classic clinical index in SGs (ROC curve 0.9821) and significant distinct discrimination in PBMC (ROC curve 0.9107). These findings are expected to gain a further insight into the pathogenesis of pSS and provide a promising candidate for the early detection of pSS.

Innate Immunity and Biological Therapies for the Treatment of Sjögren's Syndrome

Sjögren's syndrome (SS) is a systemic autoimmune disorder affecting approximately 3% of the population in the United States. This disease has a female predilection and affects exocrine glands, including lacrimal and salivary glands. Dry eyes and dry mouths are the most common symptoms due to the loss of salivary and lacrimal gland function. Symptoms become more severe in secondary SS, where SS is present along with other autoimmune diseases like systemic lupus erythematosus, systemic sclerosis, or rheumatoid arthritis. It is known that aberrant activation of immune cells plays an important role in disease progression, however, the mechanism for these pathological changes in the immune system remains largely unknown. This review highlights the role of different immune cells in disease development, therapeutic treatments, and future strategies that are available to target various immune cells to cure the disease.

Contributions of Major Cell Populations to Sjögren's Syndrome

Sjögren’s syndrome (SS) is a female dominated autoimmune disease characterized by lymphocytic infiltration into salivary and lacrimal glands and subsequent exocrine glandular dysfunction. SS also may exhibit a broad array of extraglandular manifestations including an elevated incidence of non-Hodgkin’s B cell lymphoma. The etiology of SS remains poorly understood, yet progress has been made in identifying progressive stages of disease using preclinical mouse models. The roles played by immune cell subtypes within these stages of disease are becoming increasingly well understood, though significant gaps in knowledge still remain. There is evidence for distinct involvement from both innate and adaptive immune cells, where cells of the innate immune system establish a proinflammatory environment characterized by a type I interferon (IFN) signature that facilitates propagation of the disease by further activating T and B cell subsets to generate autoantibodies and participate in glandular destruction. This review will discuss the evidence for participation in disease pathogenesis by various classes of immune cells and glandular epithelial cells based upon data from both preclinical mouse models and human patients. Further examination of the contributions of glandular and immune cell subtypes to SS will be necessary to identify additional therapeutic targets that may lead to better management of the disease.

Increased CD200 levels in peripheral blood mononuclear cells of patients with primary Sjögren's syndrome

OBJECTIVES

Primary Sjögren's syndrome (pSS) is a chronic autoimmune disease with an unknown etiology. CD200 is associated with many autoimmune diseases, but little is known about its role in pSS. This study aims to correlate the expression of CD200 with pSS and evaluate its significance.

METHODS

Plasma CD200, CD200R, and interleukin (IL)-17 levels were measured and analyzed by enzyme-linked immunosorbent assay. Messenger RNA levels of CD200 and CD200R in peripheral blood mononuclear cells (PBMCs) were quantified by quantitative real-time polymerase chain reaction (RT-qPCR). Following pretreatment of CD200-Fc, the protein levels of IL-17A were measured in PBMCs from patients and healthy controls.

RESULTS

Results showed that, compared to CD200 in healthy controls, the relative levels in PBMCs from pSS were greater than 2-fold. In addition, CD200 levels in plasma positively correlated with IL-17 levels, as well as between plasma CD200 and pSS activity indexes (including immunoglobulin G and European League Against Rheumatism SS Disease Activity Index). While CD200R levels were significantly decreased in pSS patients, no correlation could be found. Furthermore, the protein level of IL-17 decreased after pretreatment of CD200-Fc in PBMCs from pSS patients.

CONCLUSION

Our results suggested that the CD200/CD200R pathway is involved in pSS pathogenesis. It is hypothesized that regulation of IL-17 expression affects Th17 differentiation. This newly discovered pathway could give rise to a novel targeted therapy for pSS.

MiR-let-7d-3p regulates IL-17 expression through targeting AKT1/mTOR signaling in CD4+ T cells

The aberrant expression of interleukin-17 (IL-17) has been reported in the pathogenesis of autoimmune diseases, such as primary Sjögren's syndrome (pSS). However, the detailed mechanism remains poorly understood. We aim to characterize the expression of IL-17 in pSS and analyze the detailed underlying mechanism. IL-17 and microRNA miR-let-7d-3p expression were assayed by quantitative real-time PCR and Western blot, and proliferation-related protein expression was measured by Western blot. Luciferase reporter assays were performed to detect the direct regulation of IL-17 by miR-let-7d-3p. Expression of miR-let-7d-3p was negatively correlated with the expression of IL-17 in patients with pSS. Besides, the AKT1/mTOR signaling pathway was found critical for miR-let-7d-3p-mediated IL-17 expression. Furthermore, miR-let-7d-3p targeted AKT1 to bridge the regulation of IL-17. Finally, we verified AKT1 co-expression could rescue IL-17 downregulation caused by miR-let-7d-3p. Our study revealed novel mechanism that how did IL-17 was exactly modulated by miR-let-7d-3p and the potential of miR-let-7d-3p-AKT1-mTOR-IL-17 signaling as therapeutic targets for autoimmune diseases.

Identifying Key Genes and Functionally Enriched Pathways in Sjögren's Syndrome by Weighted Gene Co-Expression Network Analysis

Purpose: Sjögren’s syndrome (SS) is an autoimmune disease characterized by dry mouth and eyes. To date, the exact molecular mechanisms of its etiology are still largely unknown. The aim of this study was to identify SS related key genes and functionally enriched pathways using the weighted gene co-expression network analysis (WGCNA).

Materials and Methods: We downloaded the microarray data of 190 SS patients and 32 controls from Gene Expression Omnibus (GEO). Gene network was constructed and genes were classified into different modules using WGCNA. In addition, for the hub genes in the most related module to SS, gene ontology analysis was applied. The expression profile and diagnostic capacity (ROC curve) of interested hub genes were verified using a dataset from the GEO. Moreover, gene set enrichment analysis (GSEA) was also performed.

Results: A total of 1483 differentially expressed genes were filtered. Weighted gene coexpression network was constructed and genes were classified into 17 modules. Among them, the turquoise module was most closely associated with SS, which contained 278 genes. These genes were significantly enriched in 10 Gene Ontology terms, such as response to virus, immune response, defense response, response to cytokine stimulus, and the inflammatory response. A total of 19 hub genes (GBP1, PARP9, EPSTI1, LOC400759, STAT1, STAT2, IFIH1, EIF2AK2, TDRD7, IFI44, PARP12, FLJ20035, PARP14, ISGF3G, XAF1, RSAD2,LY6E, IFI44L, and DDX58) were identified. The expression levels of the five interested genes including EIF2AK2, GBP1, PARP12, PARP14, and TDRD7 were also confirmed. ROC curve analysis determined that the above five genes’ expression can distinguish SS from controls (the area under the curve is all greater than 0.7). GSEA suggests that the SS samples with highly expressed EIF2AK2 or TDRD7 genes are correlated with inflammatory response, interferon α response, and interferon γ response.

Conclusion: The present study applied WGCNA to generate a holistic view of SS and provide a basis for the identification of potential pathways and hub genes that may be involved in the development of SS.

Th17 Cells and the IL-23/IL-17 Axis in the Pathogenesis of Periodontitis and Immune-Mediated Inflammatory Diseases

Innate immunity represents the semi-specific first line of defense and provides the initial host response to tissue injury, trauma, and pathogens. Innate immunity activates the adaptive immunity, and both act highly regulated together to establish and maintain tissue homeostasis. Any dysregulation of this interaction can result in chronic inflammation and autoimmunity and is thought to be a major underlying cause in the initiation and progression of highly prevalent immune-mediated inflammatory diseases (IMIDs) such as psoriasis, rheumatoid arthritis, inflammatory bowel diseases among others, and periodontitis. Th1 and Th2 cells of the adaptive immune system are the major players in the pathogenesis of IMIDs. In addition, Th17 cells, their key cytokine IL-17, and IL-23 seem to play pivotal roles. This review aims to provide an overview of the current knowledge about the differentiation of Th17 cells and the role of the IL-17/IL-23 axis in the pathogenesis of IMIDs. Moreover, it aims to review the association of these IMIDs with periodontitis and briefly discusses the therapeutic potential of agents that modulate the IL-17/IL-23 axis.

Sex Effects on Gene Expression in Lacrimal Glands of Mouse Models of Sjögren Syndrome

Purpose

Sjögren syndrome is an autoimmune disease that occurs primarily in women, and is associated with lacrimal gland inflammation and aqueous-deficient dry eye. We hypothesize that sex-associated differences in lacrimal gland gene expression are very important in promoting lymphocyte accumulation in this tissue and contribute to the onset, progression, and/or severity of the inflammatory disease process. To test our hypothesis, we explored the nature and extent of sex-related differences in gene expression in autoimmune lacrimal glands.

Methods

Lacrimal glands were collected from age-matched, adult, male and female MRL/MpJ-Tnfrsf6^lpr (MRL/lpr) and nonobese diabetic/LtJ (NOD) mice. Glands were processed for the analysis of differentially expressed mRNAs by using CodeLink Bioarrays and Affymetrix GeneChips. Data were evaluated with bioinformatics and statistical software.

Results

Our results show that sex significantly influences the expression of thousands of genes in lacrimal glands of MRL/lpr and NOD mice. The immune nature of this glandular response is very dependent on the Sjögren syndrome model. Lacrimal glands of female, as compared with male, MRL/lpr mice contain a significant increase in the expression of genes related to inflammatory responses, antigen processing, and chemokine pathways. In contrast, it is the lacrimal tissue of NOD males, and not females, that presents with a significantly greater expression of immune-related genes.

Conclusions

These data support our hypothesis that sex-related differences in gene expression contribute to lacrimal gland disease in Sjögren syndrome. Our findings also suggest that factors in the lacrimal gland microenvironment are critically important in mediating these sex-associated immune effects.

Association between Periodontal Disease and Subsequent Sjögren's Syndrome: A Nationwide Population-Based Cohort Study

Xerostomia (dry mouth) is the cardinal symptom of Sjögren’s syndrome (SS), which is an autoimmune disease involving the exocrine glands and other organs. Xerostomia may predispose patients to periodontal disease (PD) and an association between SS and PD has been reported. This association may be bidirectional; therefore, we conducted this study to investigate the risk of SS in patients with PD using data from the National Health Insurance Research Database of Taiwan. A total of 135,190 patients were enrolled in our analysis. In all, 27,041 patients with PD were matched by gender, age, insured region, urbanization and income, with cases and controls in a 1:4 ratio. Both groups were followed and the risks of SS were calculated by Cox proportional hazards regression. Finally, 3292 (2.4%) patients had newly diagnosed SS. Patients with PD had a significantly higher risk of subsequent SS (903 (3.3%) vs. 2389 (2.2%), adjusted hazard 1.47, 95% confidence interval: 1.36–1.59). In conclusion, patients with PD had an approximately 50% increased risk of subsequent SS. Physicians should be aware of the symptoms and signs of SS in patients with PD.

Cutaneous and Mucosal Manifestations of Sjögren's Syndrome

Sjögren's syndrome is currently considered an "autoimmune epithelitis," as exocrine glands, especially salivary and lacrimal, are progressively destructed by an immune-mediated process associated with specific serum autoantibodies and local lymphocyte infiltrate. Xerostomia remains a key complain in patients with Sjögren's syndrome but should be evaluated also for other causes such as xerogenic medications, followed by radiation and chemotherapy for head and neck cancers, hormone disorders, infections, or other connective tissue diseases. Further, xerophtalmia (also known as dry eye) frequently associated with keratoconjunctivitis sicca cumulatively affects approximately 10-30% of the general population with increasing incidence with age and is more frequently secondary to non-autoimmune diseases. On the other hand, numerous patients with Sjögren's syndrome manifest signs of systemic dryness involving the nose, the trachea, the vagina, and the skin, suggesting that other glands are also affected beyond the exocrine epithelia. Skin involvement in Sjögren's syndrome is relatively common, and various manifestations may be present, in particular xeroderma, eyelid dermatitis, annular erythema, and cutaneous vasculitis. Additional skin non-vasculitic manifestations include livedo reticularis which may occur in the absence of vasculitis, and localized nodular cutaneous amyloidosis possibly representing lymphoproliferative diseases related to Sjögren's syndrome. The treatment of skin and mucosal manifestations in Sjögren's syndrome is similar regardless of the cause, starting from patient education to avoid alcohol and tobacco smoking and to pursue dental hygiene. In conclusion, a strict collaboration between the dermatologist and the rheumatologist is essential in the adequate management of Sjögren's syndrome skin and mucosal manifestations.

MicroRNA in Sjögren's Syndrome: Their Potential Roles in Pathogenesis and Diagnosis

Sjögren's syndrome (SS) or sicca syndrome was described by Swedish ophthalmologist Sjögren in the year 1933 for the first time. The etiology of the SS is multifunctional and includes a combination of genetic predisposition and environmental as well as epigenetic factors. It is an autoimmune disease characterized by features of systemic autoimmunity, dysfunction, and inflammation in the exocrine glands (mainly salivary and lacrimal glands) and lymphocytic infiltration of exocrine glands. In fact, the involvement of lacrimal and salivary glands results in the typical features of dry eye and salivary dysfunction (xerostomia). Only in one-third of the patients also present systemic extraglandular manifestations. T cells were originally considered to play the initiating role in the autoimmune process, while B cells were restricted to autoantibody production. In recent years, it is understood that the roles of B cells are multiple. Moreover, autoantibodies and blood B cell analysis are major contributors to a clinical diagnosis of Sjögren's syndrome. Recently, there has been rising interest in microRNA implication in autoimmunity. Unfortunately, to date, there are only a few studies that have investigated their participation in SS etiopathogenesis. The purpose of this work is to gather the data present in the literature to clarify this complex topic.

Is there a role for IL-17 in the pathogenesis of systemic sclerosis?

In systemic sclerosis (SSc) immuno-inflammatory events are central to disease development. Amongst other mediators of inflammation, interleukin 17 (IL-17) and Th17 cells have been reported to be increased in the peripheral blood and target organs including involved skin in SSc. They participate and amplify inflammatory responses by inducing the production of cytokines such as IL-6, chemokines such as CCL2 and CXCL8 (IL-8), matrix metalloproteinases-1, -2, -9 and the expression of adhesion molecules in stromal cells including fibroblasts and endothelial cells. In this respect, IL-17 and Th17 cells behave paradigmatically as documented in other autoimmune pathological conditions or infectious diseases. In experimental animal models of skin and lung fibrosis, IL-17 indirectly enhances the fibrotic process by favoring further inflammation by recruiting inflammatory cells, by activating and/or stimulating the production of TGF-β and other pro-fibrotic mediators, by inhibiting autophagy. Whether the findings generated in animal models of fibrosis can be translated to human SSc is unproven. Furthermore, it is controversial whether IL-17 directly promotes the transdifferentiation of human fibroblasts into myofibroblasts and enhances collagen production, with most of the available evidence against this possibility. The reductionist approach in which fibroblast in monolayers are cultured in plastic dishes under the influence of IL-17 limits the relevance of these findings. Further in vitro/ex vivo models with human tissues are being developed to investigate the real effect of IL-17 on extracellular matrix deposition, since agents blocking IL-17 are available for the clinic and it will be important to know whether their use in SSc would be beneficial or detrimental.

The oral microbiome

The human microbiome is receiving a great deal of attention as its role in health and disease becomes ever more apparent. The oral microbiome, perhaps due to the ease with which we can obtain samples, is arguably the most well-studied human microbiome to date. It is obvious, however, that we have only just begun to scratch the surface of the complex bacterial and bacterial–host interactions within this complex community. Here, we describe the factors which are known to influence the development of the seemingly globally conserved, core, oral microbiome and those which are likely to be responsible for the observed differences at the individual level. We discuss the paradoxical situation of maintaining a stable core microbiome which is at the same time incredibly resilient and adaptable to many different stresses encountered in the open environment of the oral cavity. Finally, we explore the interactions of the oral microbiome with the host and discuss the interactions underlying human health and disease.