Pathogenesis of Sjögren's syndrome

Altered characteristics of regulatory T cells in target tissues of Sjögren's syndrome in murine models

Sjӧgren's syndrome (SS), also known as Sjögren's disease, is a chronic autoimmune condition predominantly affecting the salivary and lacrimal glands. The disease is driven by autoimmune responses involving the activation and actions of major innate- and adaptive immune cell subsets. However, the specific characteristics and roles of regulatory T cells (Tregs) in SS remain elusive. This study seeks to clarify the main phenotypic and functional attributes of Tregs in the salivary glands and their draining lymph nodes in murine models of SS. Our flow cytometric analysis revealed that Tregs in the salivary gland-draining lymph nodes of female non-obese diabetic (NOD) mice, a spontaneous model of SS, exhibited a greater proportion of activated Tregs and fewer resting Tregs compared to Balb/c mice. Furthermore, Tregs from the salivary gland-draining lymph nodes of female C57BL/6.NOD-Aec1Aec2 (B6.NOD-Aec) mice, a model for primary SS, demonstrated significantly lower IL-10 production but markedly higher IFNγ- and IL-17 production than their C57BL/6 counterparts. Additionally, treatment of C57BL/6 Tregs with IL-7, a cytokine critical for SS pathogenesis, resulted in diminished IL-10 production and enhanced IFNγ and IL-17 production in these cells. Notably, the alterations in B6.NOD-Aec Tregs also included an increased expression of the immune-inhibitory molecule CTLA-4 compared to the C57BL/6 Tregs. Intriguingly, in vitro co-cultures of Tregs with conventional CD4 T cells and other key immune populations from lymph nodes indicated that Tregs from salivary gland-draining lymph nodes of both B6.NOD-Aec and C57BL/6 strains exhibited comparable and limited immunosuppressive effects on the proliferation and function of conventional CD4 T cells. The ability of B6.NOD-Aec Tregs to directly inflict damages to salivary gland epithelial tissues and contribute to SS pathologies through IFNγ and IL-17 that they produce warrants further investigations. In addition, enhancing the relatively weak immunosuppressive capacities of these Tregs may also serve as a viable strategy to alleviate the SS phenotype in the mouse models and potentially in patients.

Artesunate alleviates Sjögren's Syndrome by inhibiting the interferon-α signaling in plasmacytoid dendritic cells via TLR-MyD88-IRF7

Sjögren's syndrome (SS) is an autoimmune disease in which the salivary glands (SGs) and the lacrimal glands (LGs) are affected by lymphocytic infiltration and inflammation. It has been reported that interferon-α (IFN-α) released by plasmacytoid dendritic cells (pDCs) contribute to the pathology of SS, and ART has been shown to effectively ameliorates SS. Despite the current research endeavors, the mechanism of how ART works in the treatment of SS remains to be fully elucidated. Whether ART can treat SS by inhibiting IFN-α remains unclear. This hypothesis was tested both in vivo and in vitro settings during the study. The SS model mice, which were treated with ART, showed amelioration in symptoms related to dryness. RNA-seq analysis revealed strong anti-IFN-α signaling response upon ART treatment. Additional in vitro studies provided further confirmation that the application of ART inhibits the MyD88 protein expression and the nuclear translocation of IRF7. This suggests that the intervention of ART in the TLR-MyD88-IRF7 pathway plays a role in the therapeutic approach for SS. In summary, this study highlighted the therapeutic potential of ART in SS and ART inhibited the IFN-α signaling in pDCs via the TLR-MyD88-IRF7 pathway.

Downregulated GPX4 in salivary gland epithelial cells contributes to salivary secretion dysfunction in Sjogren's syndrome via lipid ROS/pSTAT4/AQP5 axis

Sjogren's syndrome (SS) is an autoimmune disease characterized by dysfunction of exocrine glands, such as salivary glands. However, the molecular mechanism of salivary secretion dysfunction in SS is still unclear. Given the significance of glutathione peroxidase 4 (GPX4) in cellular redox homeostasis, we hypothesized that dysregulation of GPX4 may play a pivotal role in the pathogenesis of salivary secretion dysfunction observed in SS. The salivary gland of SS patients and the SS mouse model exhibited reduced expression of the ferroptosis inhibitor GPX4 and the important protein aquaporin 5 (AQP5), which is involved in salivary secretion. GPX4 overexpression upregulated and GPX4 knockdown downregulated AQP5 expression in salivary gland epithelial cells (SGECs) and salivary secretion. Bioinformatics analysis of GSE databases from SS patients' salivary glands revealed STAT4 as a key intermediary regulator between GPX4 and AQP5. A higher level of nuclear pSTAT4 was observed in the salivary gland of the SS mouse model. GPX4 overexpression inhibited and GPX4 knockdown promoted STAT4 phosphorylation and nuclear translocation in SGECs. CHIP assay confirmed the binding of pSTAT4 within the promoter of AQP5 inhibiting AQP5 transcription. GPX4 downregulation accumulates intracellular lipid ROS in SGECs. Lipid ROS inhibitor ferrostatin-1 treatment during in vitro and in vivo studies confirmed that lipid ROS activates STAT4 phosphorylation and nuclear translocation in SGECs. In summary, the downregulated GPX4 in SGECs contributes to salivary secretion dysfunction in SS via the lipid ROS/pSTAT4/AQP5 axis. This study unraveled novel targets to revitalize the salivary secretion function in SS patients.

Exploring Salivary Epithelial Dysfunction in Sjögren's Disease

Sjögren's Disease (SjD) is an autoimmune disease of the exocrine tissues. Etiological events result in the loss of epithelial homeostasis alongside extracellular matrix (ECM) destruction within the salivary and lacrimal glands, followed by immune cell infiltration. In this review, we have assessed the current understanding of epithelial-mesenchymal transition (EMT)-associated changes within the salivary epithelium potentially involved in salivary dysfunction and SjD pathogenesis. We performed a PubMed literature review pertaining to the determination of pathogenic events that lead to EMT-related epithelial dysfunction and signaling in SjD. Molecular patterns of epithelial dysfunction in SjD salivary glands share commonalities with EMT mediating wound healing. Pathological changes altering salivary gland integrity and function may precede direct immune involvement while perpetuating MMP9-mediated ECM destruction, inflammatory mediator expression, and eventual immune cell infiltration. Dysregulation of EMT-associated factors is present in the salivary epithelium of SjD and may be significant in initiating and perpetuating the disease. In this review, we further highlight the gap regarding mechanisms that drive epithelial dysfunction in salivary glands in the early or subclinical pre-lymphocytic infiltration stages of SjD.

Weighted Gene Co-expression Network Analysis and Machine Learning Validation for Identifying Major Genes Related to Sjogren's Syndrome

Sjogren's syndrome (SS) is an autoimmune disorder characterized by dry mouth and dry eyes. Its pathogenic mechanism is currently unclear. This study aims to integrate weighted gene co-expression network analysis (WGCNA) and machine learning to identify key genes associated with SS. We downloaded 3 publicly available datasets from the GEO database comprising the gene expression data of 231 SS and 78 control cases, including GSE84844, GSE48378 and GSE51092, and carried out WGCNA to elucidate differences in the abundant genes. Candidate biomarkers for SS were then identified using a LASSO regression model. Totally 6 machine-learning models were subsequently utilized for validating the biological significance of major genes according to their expression. Finally, immune cell infiltration of the SS tissue was assessed using the CIBERSORT algorithm. A weighted gene co-expression network was built to divide genes into 10 modules. Among them, blue and red modules were most closely associated with SS, and showed significant enrichment in type I interferon signaling, cellular response to type I interferon and response to virus, etc. Combined machine learning identified 5 hub genes, including OAS1, EIF2AK2, IFITM3, TOP2A and STAT1. Immune cell infiltration analysis showed that SS was associated with CD8+ T cell, CD4+ T cell, gamma delta T cell, NK cell and dendritic cell activation. WGCNA was combined with machine learning to uncover genes that may be involved in SS pathogenesis, which can be utilized for developing SS biomarkers and appropriate therapeutic targets.

Association of endometriosis with Sjögren's syndrome: Genetic insights (Review)

Patients with a history of endometriosis have an increased risk of developing various autoimmune diseases such as rheumatoid arthritis, ankylosing spondylitis, systemic lupus erythematosus, multiple sclerosis and celiac disease. There is a potential association between endometriosis and an increased susceptibility for Sjögren's syndrome (SS). SS is a common chronic, inflammatory, systemic, autoimmune, multifactorial disease of complex pathology, with genetic, epigenetic and environmental factors contributing to the development of this condition. It occurs in 0.5‑1% of the population, is characterized by the presence of ocular dryness, lymphocytic infiltrations and contributes to neurological, gastrointestinal, vascular and dermatological manifestations. Endometriosis is an inflammatory, estrogen‑dependent, multifactorial, heterogeneous gynecological disease, affecting ≤10% of reproductive‑age women. It is characterized by the occurrence of endometrial tissue outside the uterine cavity, mainly in the pelvic cavity, and is associated with pelvic pain, dysmenorrhea, deep dyspareunia and either subfertility or infertility. It is still unclear whether SS appears as a secondary response to endometriosis, or it is developed due to any potential shared mechanisms of these conditions. The aim of the present review was to explore further the biological basis only of the co‑occurrence of these disorders but not their association at clinical basis, focusing on the analysis of the partially shared genetic background between endometriosis and SS, and the clarification of the possible similarities in the underlying pathogenetic mechanisms and the relevant molecular pathways.

Loss of STIM1 and STIM2 in salivary glands disrupts ANO1 function but does not induce Sjogren's disease

Sjogren's disease (SjD) is an autoimmune disease characterized by xerostomia (dry mouth), lymphocytic infiltration into salivary glands and the presence of SSA and SSB autoantibodies. Xerostomia is caused by hypofunction of the salivary glands and has been involved in the development of SjD. Saliva production is regulated by parasympathetic input into the glands initiating intracellular Ca 2+ signals that activate the store operated Ca 2+ entry (SOCE) pathway eliciting sustained Ca 2+ influx. SOCE is mediated by the STIM1 and STIM2 proteins and the ORAI1 Ca 2+ channel. However, there are no studies on the effects of lack of STIM1/2 function in salivary acini in animal models and its impact on SjD. Here we report that male and female mice lacking Stim1 and Stim2 ( Stim1/2 K14Cre ) in salivary glands showed reduced intracellular Ca 2+ levels via SOCE in parotid acini and hyposalivate upon pilocarpine stimulation. Bulk RNASeq of the parotid glands of Stim1/2 K14Cre mice showed a decrease in the expression of Stim1/2 but no other Ca 2+ associated genes mediating saliva fluid secretion. SOCE was however functionally required for the activation of the Ca 2+ activated chloride channel ANO1. Despite hyposalivation, ageing Stim1/2 K14Cre mice showed no evidence of lymphocytic infiltration in the glands or elevated levels of SSA or SSB autoantibodies in the serum, which may be linked to the downregulation of the toll-like receptor 8 ( Tlr8 ). By contrast, salivary gland biopsies of SjD patients showed increased STIM1 and TLR8 expression, and induction of SOCE in a salivary gland cell line increased the expression of TLR8 . Our data demonstrate that SOCE is an important activator of ANO1 function and saliva fluid secretion in salivary glands. They also provide a novel link between SOCE and TLR8 signaling which may explain why loss of SOCE does not result in SjD.

Associations between TNFSF13B polymorphisms and primary Sjögren's syndrome susceptibility in primary Sjögren's syndrome patients: A meta-analysis

OBJECTIVE

B-cell activating factor (BAFF) is a key regulator of primary Sjögren's syndrome (pSS), which is characterized by B-lymphocyte hyperactivity. BAFF, also known as tumor necrosis factor ligand superfamily member 13B, is encoded by TNFSF13B. This study aimed to explore the possible relationships between five single-nucleotide polymorphisms (SNPs) of TNFSF13B (rs9514827, rs1041569, rs9514828, rs1224141, and rs12583006) and pSS susceptibility.

METHODS

We searched the following databases for articles on TNFSF13B polymorphism and pSS published up to January 2023: PubMed, Cochrane, Elsevier, Web of Science, CNKI, CQVIP, and WanFang. The odds ratios (with 95% confidence intervals) of genotypes and SNP alleles of TNFSF13B were investigated in patients with pSS to determine their relationships with pSS.

RESULTS

This meta-analysis employing the fixed-effect model comprised three studies of pSS patients and randomly selected healthy controls (HCs), revealing statistically significant relationships between pSS susceptibility and two SNPs: rs1041569 and rs12583006. Because rs1041569 was not in Hardy-Weinberg equilibrium in the HC group, it was eliminated from the analysis.

CONCLUSIONS

Polymorphisms in the BAFF (TNFSF13B) gene were related to vulnerability to pSS among pSS patients and HCs alike. The SNP rs12583006 was significantly related to pSS susceptibility in pSS patients.

The P2X7 Receptor in Autoimmunity

The P2X7 receptor (P2X7R) is an ATP-gated nonselective cationic channel that, upon intense stimulation, can progress to the opening of a pore permeable to molecules up to 900 Da. Apart from its broad expression in cells of the innate and adaptive immune systems, it is expressed in multiple cell types in different tissues. The dual gating property of P2X7R is instrumental in determining cellular responses, which depend on the expression level of the receptor, timing of stimulation, and microenvironmental cues, thus often complicating the interpretation of experimental data in comprehensive settings. Here we review the existing literature on P2X7R activity in autoimmunity, pinpointing the different functions in cells involved in the immunopathological processes that can make it difficult to model as a druggable target.

Marginal Zone B (MZB) Cells: Comparison of the Initial Identification of Immune Activity Leading to Dacryoadenitis and Sialadenitis in Experimental Sjögren's Syndrome

Although multiple mouse strains have been advanced as models for Sjögren's syndrome (SS), which is a human systemic autoimmune disease characterized primarily as the loss of lacrimal and salivary gland functions, the C57BL/6.NOD-Aec1Aec2 recombinant inbred (RI) mouse derived from the NOD/ShiLtJ line is considered one of the more appropriate models exhibiting virtually all the characteristics of the human disease. This mouse model, as well as other mouse models of SS, have shown that B lymphocytes are essential for the onset and development of observed clinical manifestations. Recently, studies carried out in the C57BL/6.IL14α transgenic mouse have provided clear evidence that the marginal zone B (MZB) cell population is directly involved in the early pathological events initiating the development of the clinical SS disease, as well as late-stage lymphomagenesis resulting in B-cell lymphomas. Since MZB cells are difficult to study in vivo and in vitro, we carried out a series of ex vivo investigations that utilize temporal global RNA transcriptomic analyses to profile differentially expressed genes exhibiting temporal upregulation during the initial onset and subsequent development of pathophysiological events within the lacrimal and salivary gland tissues per se or associated with the leukocyte cell migrations into these glands. The initial transcriptomic analyses revealed that while the upregulated gene expression profiles obtained from lacrimal and salivary glands overlap, multiple genetic differences exist between the defined activated pathways. In the current study, we present a concept suggesting that the initial pathological events differ between the two glands, yet the subsequent upregulated TLR4/TLR3 signal transduction pathway that activates the type-1 interferon signature appears to be identical in the two glands and indicates an autoimmune response against dsRNA, possibly a virus. Here, we attempt to put these findings into perspective and determine how they can impact the design of future therapeutic protocols.

VDR Gene Single Nucleotide Polymorphisms and Autoimmunity: A Narrative Review

The vitamin D/Vitamin D receptor (VDR) axis is crucial for human health as it regulates the expression of genes involved in different functions, including calcium homeostasis, energy metabolism, cell growth and differentiation, and immune responses. In particular, the vitamin D/VDR complex regulates genes of both innate and adaptive immunity. Autoimmune diseases are believed to arise from a genetic predisposition and the presence of triggers such as hormones and environmental factors. Among these, a role for Vitamin D and molecules correlated to its functions has been repeatedly suggested. Four single nucleotide polymorphisms (SNPs) of the VDR gene, ApaI, BsmI, TaqI, and FokI, in particular, have been associated with autoimmune disorders. The presence of particular VDR SNP alleles and genotypes, thus, was observed to modulate the likelihood of developing diverse autoimmune conditions, either increasing or reducing it. In this work, we will review the scientific literature suggesting a role for these different factors in the pathogenesis of autoimmune conditions and summarize evidence indicating a possible VDR SNP involvement in the onset of these diseases. A better understanding of the role of the molecular mechanisms linking Vitamin D/VDR and autoimmunity might be extremely useful in designing novel therapeutic avenues for these disorders.

Extracellular vesicles as a new horizon in the diagnosis and treatment of inflammatory eye diseases: A narrative review of the literature

Extracellular vesicles include exosomes, microvesicles, and apoptotic bodies. Their cargos contain a diverse variety of lipids, proteins, and nucleic acids that are involved in both normal physiology and pathology of the ocular system. Thus, studying extracellular vesicles may lead to a more comprehensive understanding of the pathogenesis, diagnosis, and even potential treatments for various diseases. The roles of extracellular vesicles in inflammatory eye disorders have been widely investigated in recent years. The term "inflammatory eye diseases" refers to a variety of eye conditions such as inflammation-related diseases, degenerative conditions with remarkable inflammatory components, neuropathy, and tumors. This study presents an overview of extracellular vesicles' and exosomes' pathogenic, diagnostic, and therapeutic values in inflammatory eye diseases, as well as existing and potential challenges.

CXCL9, 10, 11/CXCR3 Axis Contributes to the Progress of Primary Sjogren's Syndrome by Activating GRK2 to Promote T Lymphocyte Migration

Primary Sjogren's syndrome (pSS) is a systemic autoimmune disease that causes dysfunction of secretory glands and the specific pathogenesis is still unknown. The CXCL9, 10, 11/CXCR3 axis and G protein-coupled receptor kinase 2 (GRK2) involved in many inflammation and immunity processes. We used NOD/Ltj mice, a spontaneous SS animal model, to elucidate the pathological mechanism of CXCL9, 10, 11/CXCR3 axis promoting T lymphocyte migration by activating GRK2 in pSS. We found that CD4 + GRK2, Th17 + CXCR3 was apparently increased and Treg + CXCR3 was significantly decreased in the spleen of 4W NOD mice without sicca symptom compared to ICR mice (control group). The protein levels of IFN-γ, CXCL9, 10, 11 increased in submandibular gland (SG) tissue accompanied by obvious lymphocytic infiltration and Th17 cells overwhelmingly infiltrated relative to Treg cells at the sicca symptom occurs, and we found that the proportion of Th17 cells was increased, whereas that of Treg cells was decreased in spleen. In vitro, we used IFN-γ to stimulate human salivary gland epithelial cells (HSGECs) co-cultured with Jurkat cells, and the results showed that CXCL9, 10, 11 was increased by IFN-γ activating JAK2/STAT1 signal pathway and Jurkat cell migration increased with the raised of cell membrane GRK2 expression. HSGECs with tofacitinib or Jurkat cells with GRK2 siRNA can reduce the migration of Jurkat cells. The results indicate that CXCL9, 10, 11 significantly increased in SG tissue through IFN-γ stimulating HSGECs, and the CXCL9, 10, 11/CXCR3 axis contributes to the progress of pSS by activating GRK2 to promote T lymphocyte migration.

Reduced Tear Thrombospondin-1/Matrix Metalloproteinase-9 Ratio Can Aid in Detecting Sjögren's Syndrome Etiology in Patients with Dry Eye

Differentiating patients with Sjögren's syndrome (SS)‐associated dry eye from non‐SS dry eye is critical for monitoring and appropriate management of possible sight‐ or life‐threatening extraglandular complications associated with SS. We tested whether reduced tear levels of immunoregulatory thrombospondin (TSP)‐1, which also inhibits matrix metalloproteinase (MMP)‐9, would reflect SS pathogenesis aiding the identification of patients with SS‐dry eye. Total of 61 participants, including healthy controls (n = 20), patients with non‐SS dry eye (n = 20) and SS‐dry eye (n = 21) were enrolled prospectively. Tear TSP‐1 and MMP‐9 levels were measured using a custom magnetic bead‐based multi‐plex assay in a masked manner. Analyte concentrations were assessed further according to ocular surface and tear film parameters. Relative to median tear TSP‐1 (308 ng/ml) and MMP‐9 (1.9 ng/ml) levels in the control group, significantly higher proportion of patients with SS‐dry eye than non‐SS had lower tear TSP‐1 levels (55% vs. 29%, odds ratio [OR] = 3, 95% confidence interval [CI] = 1.64 to 5.35, p < 0.05) and higher tear MMP‐9 levels (65% vs. 24%, OR = 5.8, 95% CI = 4.46 to 19.81, p < 0.05), respectively. The tear TSP‐1/MMP‐9 ratio was significantly reduced in patients with SS‐dry eye compared to non‐SS (B = −2.36, 95% CI = −3.94 to −0.0.79, p < 0.05), regardless of tear MMP‐9 levels. Patients with a lower ratio were 2.3 times more likely to have SS (OR = 0.28, 95% CI = 0.1 to 0.75, p < 0.05). This ratio showed significant inverse correlations with clinical parameters (conjunctival and corneal staining scores). Our results denote that tear TSP‐1/MMP‐9 ratio can be useful in identifying patients with dry eye with underlying SS and used as a screening test.

Exposure to environmental air pollutants as a risk factor for primary Sjögren's syndrome

Background

Environmental etiology of primary Sjögren's syndrome (pSS), an autoimmune disease, has been proposed. This study determined whether the exposure to air pollutants was an independent risk factor for pSS.

Methods

Participants were enrolled from a population-based cohort registry. Daily average concentrations of air pollutants from 2000 to 2011 were divided into 4 quartiles. Adjusted hazard ratios (aHRs) of pSS for exposure to air pollutants were estimated in a Cox proportional regression model adjusting for age, sex, socioeconomic status, and residential areas. A subgroup analysis stratified by sex was conducted to validate the findings. Windows of susceptibility indicated years of exposure which contributed the most to the observed association. Ingenuity Pathway Analysis was used to identify underlying pathways of air pollutant-associated pSS pathogenesis, using Z-score visualization.

Results

Two hundred patients among 177,307 participants developed pSS, with a mean age of 53.1 years at acumulative incidence of 0.11% from 2000 to 2011. Exposure to carbon monoxide (CO), nitric oxide (NO), and methane (CH4) was associated with a higher risk of pSS. Compared to those exposed to the lowest concentration level, the aHRs for pSS were 2.04 (95%CI=1.29-3.25), 1.86 (95%CI=1.22-2.85), and 2.21 (95%CI=1.47-3.31) for those exposed to high levels of CO, NO, and CH4, respectively. The findings persisted in the subgroup analysis, in which females exposed to high levels of CO, NO, and CH4 and males exposed to high levels of CO were associated with significantly great risk of pSS. The cumulative effect of air pollution on pSS was time-dependent. The underlying cellular mechanisms involved chronic inflammatory pathways including the interleukin-6 signaling pathway.

Conclusion

Exposure to CO, NO, and CH4 was associated with a high risk of pSS, which was biologically plausible.

Omega 6 polyunsaturated fatty acids in red blood cell membrane are associated with xerostomia and taste loss in patients with breast cancer

Chemosensory and physical complaints are common disorders in cancer patients under chemotherapy treatments that may affect the food intake, leading to a decreased quality of life. Lipid metabolism is a major pathway of cancer proliferation, where erythrocyte membrane phospholipids and their fatty acid composition are promising tools for monitoring metabolic pathways. Relationship between lipid profile in erythrocyte membrane phospholipids and chemosensory alterations in 44 newly diagnosed patients with breast cancer was here investigated. Smell changes and xerostomia were the most common complaints, with xerostomia as the main influencing factor on the development of other taste disorders. Lipid profiles revealed significant negative correlation between diminution of linoleic acid levels and xerostomia as well as positive correlation between increased arachidonic acid and salty taste. The involvement of these polyunsaturated lipids suggests the importance of oxidative and nutritional conditions of cancer patients, which can affect the molecular status for taste signals.

Sjögren's Syndrome and Viral Infections

Sjögren's syndrome (SS) is a systemic autoimmune disease, characterized by lymphocytic infiltration of the secretory glands. This leads to dryness of the main mucosal surfaces such as the mouth, eyes, nose, larynx, pharynx, and vagina. Although there is little morbidity data at the initial diagnosis, SS may be a serious disease, with extra mortality caused by hematological cancer. The cause of SS is unknown, but factors postulated to play a role include genetic and environmental factors, hormonal abnormality, and viral infection. Under the influence of these factors, the immune system becomes abnormal and the tissue is damaged. In this study, we summarize recent developments in our understanding of the relationship between SS and viral infections, including Epstein-Barr virus (EBV), hepatitis C virus (HCV), human T cell lymphotropic virus type 1 (HTLV-1), cytomegalovirus (CMV), and human immunodeficiency virus (HIV).

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.

Primary Immune Responses and Affinity Maturation Are Controlled by IgD

Mature B cells co-express IgM and IgD B cell antigen receptors (BCR) on their surface. While IgM BCR expression is already essential at early stages of development, the role of the IgD-class BCR remains unclear as most B cell functions appeared unchanged in IgD-deficient mice. Here, we show that IgD-deficient mice have an accelerated rate of B cell responsiveness as they activate antibody production within 24h after immunization, whereas wildtype (WT) animals required 3 days to activate primary antibody responses. Strikingly, soluble monovalent antigen suppresses IgG antibody production induced by multivalent antigen in WT mice. In contrast, IgD-deficient mice were not able to modulate IgG responses suggesting that IgD controls the activation rate of B cells and subsequent antibody production by sensing and distinguishing antigen-valences. Using an insulin-derived peptide we tested the role of IgD in autoimmunity. We show that primary autoreactive antibody responses are generated in WT and in IgD-deficient mice. However, insulin-specific autoantibodies were detected earlier and caused more severe symptoms of autoimmune diabetes in IgD-deficient mice as compared to WT mice. The rapid control of autoimmune diabetes in WT animals was associated with the generation of high-affinity IgM that protects insulin from autoimmune degradation. In IgD-deficient mice, however, the generation of high-affinity protective IgM is delayed resulting in prolonged autoimmune diabetes. Our data suggest that IgD is required for the transition from primary, highly autoreactive, to secondary antigen-specific antibody responses generated by affinity maturation.

A New Screening Questionnaire to Identify Patients With Dry Eye With a High Likelihood of Having Sjögren Syndrome

PURPOSE

To develop a screening questionnaire to identify patients with dry eye with a high likelihood of having underlying Sjögren syndrome (SS).

METHODS

This was a cross-sectional study of participants with dry eye complaints who were self-referred or referred by an ophthalmologist to the Sjögren's International Collaborative Clinical Alliance study. Symptoms and ocular surface examination findings were candidate predictors. Univariable and multivariable logistic regression analyses were performed to estimate odds ratios (ORs) and 95% confidence intervals (95% CI) for the association of a symptom and/or ocular sign with SS. Area under the receiver operating characteristic curve (AUC) was used to summarize the predictive ability of different regression models and the derived likelihood score.

RESULTS

Four questions were statistically significant in the final multivariable model: 1) Is your mouth dry when eating a meal? [Yes = OR 1.63 (1.18-2.26)]; 2) Can you eat a cracker without drinking a fluid or liquid? [No = OR 1.46 (1.06-2.01)]; 3) How often do you have excessive tearing? [None of the time = OR 4.06 (1.81-9.10)]; and 4) Are you able to produce tears? [No = OR 2.24 (1.62-3.09)]. The SS likelihood score had an AUC of 0.70 (95% CI, 0.66-0.73), and when including tear break-up time and conjunctival staining, it yielded an AUC of 0.79 (95% CI, 0.77-0.82).

CONCLUSIONS

This questionnaire can be used to identify patients with dry eye with a high likelihood of having SS. With future refinement and validation, this screening tool could be used alone or in combination with examination findings to identify patients with SS earlier, thereby facilitating better clinical outcomes.

The NZB/W F1 mouse model for Sjögren's syndrome: A historical perspective and lessons learned

Sjögren's syndrome (SS) is a chronic rheumatic autoimmune disorder affecting multiple organ systems. The clinical findings in SS patients show considerable heterogeneity and overlap with other autoimmune diseases. In addition, the autoimmune response in SS initiates several years before the appearance of clinical symptoms. Thus, understanding the pathogenic mechanisms involved in the disease process have been a challenge. Several animal model systems of SS-like disease have been developed to overcome these issues. The New Zealand Black (NZB) x New Zealand White (NZW) F1 (NZB/W F1) mouse represents the first spontaneous mouse model of SS. In this review, we provide a historical perspective and detailed description of this mouse model focusing on exocrine gland histopathology, autoantibody populations, and glandular dysfunction. Considering that NZB/W F1 mice also develop a systemic lupus erythematosus (SLE)-like disease, this mouse model mimics the clinical presentation of polyautoimmunity seen in a sizable subset of SS patients. It is plausible that such patients will require distinct therapeutic interventions necessary to treat both SLE and SS. Therefore, the NZB/W F1 mouse is a powerful tool to decipher pathogenic mechanisms involved in SS related polyautoimmunity and develop appropriate therapeutic strategies.

Total glucosides of paeony (TGP) alleviates constipation and intestinal inflammation in mice induced by Sjögren's syndrome

ETHNOPHARMACOLOGICAL RELEVANCE

Sjögren's syndrome (SS) is an autoimmune disease and can cause gastrointestinal disorders such as constipation and intestinal inflammation. As a kind of medicinal material, Paeonia lactiflora Pall has a variety of pharmacological effects, and it is also an indispensable component in many pharmaceutical preparations, which has been widely concerned by the medical and pharmaceutical circles. Total glucosides of paeony (TGP) is a mixture of biologically active compounds extracted from the root of Paeonia lactiflora Pall and has therapeutic effects on a variety of autoimmune diseases.

AIM OF THE STUDY

To investigate the therapeutic effect of TGP on constipation and intestinal inflammation in mice modeled by SS, and to provide a basis for clinical research.

MATERIALS AND METHODS

The SS model was set up by submandibular gland (SMG) immune induction method and then treated with TGP for 24 weeks. The fecal characteristics were observed and the fecal number and moisture content were measured. Colonic pathology was observed by H&E staining. The levels of serum P substance (SP), vasoactive intestinal peptide (VIP), interleukin (IL)-1β, tumor necrosis factor (TNF)-α, nuclear factor (NF)-κB, nitric oxide (NO), and nitric oxide synthase (NOS) were determined by enzyme linked immunosorbent assay (ELISA) and microplate method, respectively. Reverse transcription polymerase chain reaction (RT-PCR) was employed to analyze the mRNA expression of c-kit and stem cell factor (SCF) in colon.

RESULTS

Compared with the model group, the dry and rough condition of the feces was improved, and the fecal gloss, number and moisture content significantly increased after the administration of TGP capsules. Meanwhile, TGP treatment improved colonic pathological damage, inhibited the serum concentrations of NO, NOS, IL-1β, TNF-α, NF-κB and SP, increased serum VIP concentration, and up-regulated mRNA expression of SCF and c-kit in colon.

CONCLUSIONS

TGP could obviously attenuate SS-mediated constipation and intestinal inflammation in mice by acting on some intestinal motility related factors and inflammatory factors.

Antibodies to the Muscarinic Acetylcholine Receptor M3 in Primary Biliary Cholangitis Inhibit Receptor Function on Cholangiocytes

Background and Aims: In primary biliary cholangitis (PBC), antibodies to a peptide of the muscarinic acetylcholine receptor 3 (mAChR3) have been described. Since the mAChR3 is expressed on cholangiocytes and mAChR3-signaling is involved in the pathogenesis of chronic inflammatory biliary diseases, we wanted to investigate whether anti-mAChR3-antibodies influence the function of the receptor and the proliferative response of cholangiocytes. Methods: Immunoglobulins were isolated by ammonium sulfate precipitation using sera from patients with PBC (n = 63) and with other chronic liver disorders (n = 150). All immunoglobulins were analyzed by a luminometric assay using Chinese hamster ovary (CHO) cells overexpressing the mAChR3 and cholangiocytes (TFK-1-cells) expressing the receptor constitutively. Cell proliferation was measured by ³H-thymidine assay. PBC patients were also analyzed in the follow-up. Results: Antibodies inhibiting the mAChR3 were found in 49 and 79% of PBC patients using CHO-cells or TFK-1-cells, respectively, but only in up to 26% of controls (p < 0.01). Stimulatory antibodies were hardly detected. Antibody reactivity only marginally changed during the course of the disease, independently of the choice of treatment (ursodeoxycholic acid, immunosuppressive therapy, or no medication). There was no correlation with laboratory, clinical or histological parameters, but the antibodies were more frequently found in PBC patients with a benign course (96%) than in patients with active disease progressing to late stages within 10 years (57%; p < 0.01). Proliferation of cells was not influenced by immunoglobulins from PBC-patients. Conclusion: Sera from patients with PBC contain inhibitory antibodies to the mAChR3 on cholangiocytes (TFK-1 cells) without influencing TFK-1-cell proliferation. These antibodies were predominantly observed in patients with non-progressing PBC.

A Multivalent ICAM-1 Binding Nanoparticle which Inhibits ICAM-1 and LFA-1 Interaction Represents a New Tool for the Investigation of Autoimmune-Mediated Dry Eye

The autoimmune disorder, Sjögren’s syndrome (SS), is characterized by lymphocytic infiltration and loss of function of exocrine glands such as the lacrimal gland (LG) and salivary gland. SS-associated changes in the LG are associated with the development of autoimmune-mediated dry eye disease. We have previously reported the accumulation of intercellular adhesion molecule 1 (ICAM-1) in the LG of Non-Obese Diabetic (NOD) mice, a murine model of autoimmune-mediated dry eye in SS, in both LG acinar cells and infiltrating lymphocytes. ICAM-1 initiates T-cell activation and can trigger T-cell migration through binding to lymphocyte function-associated 1 antigen (LFA). To modulate this interaction, this study introduces a new tool, a multivalent biopolymeric nanoparticle assembled from a diblock elastin-like polypeptide (ELP) using the S48I48 (SI) ELP scaffold fused with a mouse ICAM-1 targeting peptide to form IBP-SI. IBP-SI forms a multivalent, monodisperse nanoparticle with a radius of 21.9 nm. Unlike the parent SI, IBP-SI binds mouse ICAM-1 and is internalized by endocytosis into transfected HeLa cells before it accumulates in lysosomes. In vitro assays measuring lymphocyte adhesion to Tumor Necrosis Factor TNF-α-treated bEnd.3 cells, which express high levels of ICAM-1, show that adhesion is inhibited by IBP-SI but not by SI, with IC₅₀ values of 62.7 μM and 81.2 μM, respectively, in two different assay formats. IBP-SI, but not SI, also blocked T-cell proliferation in a mixed lymphocyte reaction by 74% relative to proliferation in an untreated mixed cell reaction. These data suggest that a biopolymeric nanoparticle with affinity for ICAM-1 can disrupt ICAM-1 and LFA interactions in vitro and may have further utility as an in vivo tool or potential therapeutic.

Agonist-induced 4-1BB activation prevents the development of Sjӧgren's syndrome-like sialadenitis in non-obese diabetic mice

Activation of costimulatory receptor 4-1BB enhances T helper 1 (Th1) and CD8 T cell responses in protective immunity, and prevents or attenuates several autoimmune diseases by increasing Treg numbers and suppressing Th17 or Th2 effector response. We undertook this study to elucidate the impact of enforced 4-1BB activation on the development of Sjögren's syndrome (SS)-like sialadenitis in non-obese diabetic (NOD) model of this disease. An anti-4-1BB agnostic antibody was intraperitoneally injected to female NOD mice aged 7 weeks, prior to the disease onset that occurs around 10-11 weeks of age, 3 times weekly for 2 weeks, and the mice were analyzed for SS pathologies at age 11 weeks. The salivary flow rate was markedly higher in the anti-4-1BB-treated NOD mice compared to the IgG-treated controls. Anti-4-1BB treatment significantly reduced the leukocyte infiltration of the submandibular glands (SMGs) and the levels of serum antinuclear antibodies. Flow cytometric analysis showed that the percentages of CD4 T cells, Th17 cells and plasmacytoid dendritic cells among SMG leukocytes were markedly reduced by anti-4-1BB treatment, in conjunction with a reduction in SMG IL-23p19 mRNA levels and serum IL-17 concentrations. Although the proportion of Tregs and IL-10 mRNA levels in SMGs were not altered by 4-1BB activation, IL-10 mRNA levels in salivary gland-draining lymph nodes and serum IL-10 concentrations were both markedly increased. While anti-4-1BB treatment did not affect the amount of Th1 cells and IFNγ mRNA in the SMGs, it increased these measurables in salivary gland-draining lymph nodes. Hence, agonistic activation of 4-1BB impedes the development of SS-like sialadenitis and hyposalivation.

Comparison of MicroRNA Expression in Tears of Normal Subjects and Sjögren Syndrome Patients

Purpose

Deregulated expression of several microRNAs (miRNAs) in sera or salivary glands of patients with Sjögren syndrome (SS) has been reported. However, none have investigated miRNAs in samples that can represent lacrimal glands. We compared the miRNAs expression in the tears of SS patients and healthy controls. Moreover, we investigated the correlation between miRNAs expression and ocular staining score (OSS).

Methods

Individual tear samples were collected from 18 SS patients and 8 age-matched controls. Clinical ophthalmologic assessments included Schirmer I test, tear film breakup time (tBUT), and OSS. The expression of 43 different miRNAs in tears was measured using real-time polymerase chain reaction, and compared between the SS patients and controls. And we also compared between the three groups of control, primary SS, and secondary SS patients. The correlation between the miRNA expression and OSS was evaluated.

Results

The expression levels of miR-16-5p, miR-34a-5p, miR-142-3p, and miR-223-3p were significantly upregulated in patients with SS when compared with those in the control group (P < 0.05). The expression of 10 miRNAs (miR-30b-5p, miR-30c-5p, miR-30d-5p, miR-92a-3p, miR-134-5p, miR-137, miR-302d-5p, miR-365b-3p, miR-374c-5p, miR-487b-3p) was significantly downregulated in the SS patients (P < 0.05). Eight miRNAs showed statistically significant differences between the three groups of control, primary SS and secondary SS. All 14 miRNAs with significant differences in SS patients and control group were not significantly correlated with OSSs.

Conclusions

The 14 differentially expressed miRNAs may be involved in the pathogenesis of SS, in particular, related to autoimmunity and neuropathy.

Catalpol ameliorates Sjögren's Syndrome by modulating interplay of T and B cells

Catalpol is an active ingredient of Rehmanniae Radix, a medical herb used frequently in treating primary Sjogren's Syndrome (pSS). However, no study has assessed the therapeutic effects of catalpol in treating Sjogren's Syndrome. This study aimed to investigate the therapeutic effects of catalpol for pSS by evaluating the water consumption, stimulated salivary flow rates, sialadenitis, T cell subsets and related cytokine levels. Catalpol treated mice had improved stimulated salivary flow rates and water consumption compared to mice from the control group. Catalpol also reduced the lymphocytic infiltration and prevented the formation of ectopic germinal centers. These effects, especially in the catalpol high dose group, were associated with elevated CD4⁺ CXC-R5⁺ PD-1⁺ Foxp3⁺ T follicular regulatory (Tfr) cells (1.572 % vs 1.118 %, P = 0.0005) and a higher ratio of Tfr cells to T follicular helper (Tfh) cells (2.137 vs 1.541, P = 0.0007). Downregulated levels of IFN-γ and BAFF in serum and submandibular glands were also noted in catalpol treated groups. Our work indicated that catalpol might be a potential drug for treating pSS by regulating the interplay between T and B cells.

Molecular Targeting of Immunosuppressants Using a Bifunctional Elastin-Like Polypeptide

Elastin-Like Polypeptides (ELP) are environmentally responsive protein polymers which are easy to engineer and biocompatible, making them ideal candidates as drug carriers. Our team has recently utilized ELPs fused to FKBP12 to carry Rapamycin (Rapa), a potent immunosuppressant. Through high affinity binding to Rapa, FKBP carriers can yield beneficial therapeutic effects and reduce the off-site toxicity of Rapa. Since ICAM-1 is significantly elevated at sites of inflammation in diverse diseases, we hypothesized that a molecularly targeted ELP carrier capable of binding ICAM-1 might have advantageous properties. Here we report on the design, characterization, pharmacokinetics, and biodistribution of a new ICAM-1-targeted ELP Rapa carrier (IBPAF) and its preliminary characterization in a murine model exhibiting elevated ICAM-1. Lacrimal glands (LG) of male NOD mice, a disease model recapitulating the autoimmune dacryoadenitis seen in Sjögren's Syndrome patients, were analyzed to confirm that ICAM-1 was significantly elevated in the LG relative to control male BALB/c mice (3.5-fold, p < 0.05, n = 6). In vitro studies showed that IBPAF had significantly higher binding to TNF-α-stimulated bEnd.3 cells which overexpress surface ICAM-1, relative to nontargeted control ELP (AF)(4.0-fold, p < 0.05). A pharmacokinetics study in male NOD mice showed no significant differences between AF and IBPAF for plasma half-life, clearance, and volume of distribution. However, both constructs maintained a higher level of Rapa in systemic circulation compared to free Rapa. Interestingly, in the male NOD mouse, the accumulation of IBPAF was significantly higher in homogenized LG extracts compared to AF at 2 h (8.6 ± 6.6% versus 1.3 ± 1.3%, respectively, n = 5, p < 0.05). This accumulation was transient with no differences detected at 8 or 24 h. This study describes the first ICAM-1 targeted protein-polymer carrier for Rapa that specifically binds to ICAM-1 in vitro and accumulates in ICAM-1 overexpressing tissue in vivo, which may be useful for molecular targeting in diverse inflammatory diseases where ICAM-1 is elevated.

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.

DNA-stimulated cell death: implications for host defence, inflammatory diseases and cancer

The immune system detects disturbances in homeostasis that occur during infection, sterile tissue damage and cancer. This initiates immune responses that seek to eliminate the trigger of immune activation and to re-establish homeostasis. At the same time, these mechanisms can also play a crucial role in the progression of disease. The occurrence of DNA in the cytosol constitutes a potent trigger for the innate immune system, governing the production of key inflammatory cytokines such as type I interferons and IL-1β. More recently, it has become clear that cytosolic DNA also triggers other biological responses, including various forms of programmed cell death. In this article, we review the emerging literature on the pathways governing DNA-stimulated cell death and the current knowledge on how these processes shape immune responses to exogenous and endogenous challenges.

Salivary Gland Stem Cells Age Prematurely in Primary Sjögren's Syndrome

OBJECTIVE

A major characteristic of the autoimmune disease primary Sjögren's syndrome (SS) is salivary gland (SG) hypofunction. The inability of resident SG stem cells (SGSCs) to maintain homeostasis and saliva production has never been explained and limits our comprehension of mechanisms underlying primary SS. The present study was undertaken to investigate the role of salivary gland stem cells in hyposalivation in primary SS.

METHODS

SGSCs were isolated from parotid biopsy samples from controls and patients classified as having primary SS or incomplete primary SS, according to the American College of Rheumatology/European League Against Rheumatism criteria. Self-renewal and differentiation assays were used to determine SGSC regenerative potential, RNA was extracted for sequencing analysis, single telomere length analysis was conducted to determine telomere length, and frozen tissue samples were used for immunohistochemical analysis.

RESULTS

SGSCs isolated from primary SS parotid gland biopsy samples were regeneratively inferior to healthy control specimens. We demonstrated that SGSCs from samples from patients with primary SS are not only lower in number and less able to differentiate, but are likely to be senescent, as revealed by telomere length analysis, RNA sequencing, and immunostaining. We further found that SGSCs exposed to primary SS-associated proinflammatory cytokines we induced to proliferate, express senescence-associated genes, and subsequently differentiate into intercalated duct cells. We also localized p16+ senescent cells to the intercalated ducts in primary SS SG tissue, suggesting a block in SGSC differentiation into acinar cells.

CONCLUSION

This study represents the first characterization of SGSCs in primary SS, and also the first demonstration of a linkage between an autoimmune disease and a parenchymal premature-aging phenotype. The knowledge garnered in this study indicates that disease-modifying antirheumatic drugs used to treat primary SS are not likely to restore saliva production, and should be supplemented with fresh SGSCs to recover saliva production.

The evaluation of the Myxovirus Resistance 1 protein in serum and saliva to monitor disease activation in primary Sjögren's syndrome

OBJECTIVE

Primary Sjögren's syndrome (pSjS) is a chronic autoimmune disease that causes dry eye and mouth. No laboratory parameters to monitor the activation of this disease have been identified. Therefore, any possible relationships between salivary and blood myxovirus resistance 1 (MX1) and pSjS must be prospectively studied.

METHODS

Thirty female patients with pSjS, 30 women with rheumatoid arthritis (RA) without secondary Sjögren's syndrome (SjS) and 28 healthy control women were enrolled in this investigation. Analyses of MX1 by the enzyme-linked immunosorbent assay (ELISA) method, SS-A (Ro) and SS-B (La) tests by the strip immunoblot method, anti-nuclear antibody (ANA) tests by immunofluorescence and the measurement of serum rheumatoid factor (RF), C3, C4, immunoglobulin A (IgA), immunoglobulin M (IgM), and immunoglobulin G (IgG) were performed.

RESULTS

The serum level of MX1 in patients without Raynaud phenomenon was higher than in those with Raynaud phenomenon (p:0.029, p<0.05, statistically significant). There was a statistically significant positive association between hemoglobin levels and MX1 serum levels. No statistically significant association was found among the other parameters. Low MX1 levels were shown to be associated with both a low disease activity score based on the European League Against Rheumatism (EULAR) Sjögren's Syndrome Disease Activity Index (ESSDAI) and hydroxychloroquine use in all patients.

CONCLUSION

MX1 levels have a considerable impact on the assessment of the disease activity in SjS. We believe that more-comprehensive studies should be performed on patients with pSjS who do not use hydroxychloroquine to prove this relationship and that MX1 levels should be used as a routine marker for the assessment of pSjS disease activity. Further studies are needed to create awareness of the role that MX1 has in the diagnosis of pSjS, which may help to uncover novel pathways for new therapeutic modalities.

Comorbid connective tissue diseases and autoantibodies in lymphangioleiomyomatosis: a retrospective cohort study

BACKGROUND

Lymphangioleiomyomatosis (LAM) and connective tissue diseases (CTDs) occur more frequently among women than men. We investigated the frequency of comorbid CTD and positive serum autoantibody findings in patients with LAM.

METHODS

A total of 152 patients with LAM were prospectively and consecutively registered in the National Hospital Organization Kinki-Chuo Chest Medical Centre cohort. The clinical data were retrospectively analysed, and patients were categorised into the following three groups: a CTD group, a non-CTD-autoantibody-positive group, and a non-CTD-autoantibody-negative group.

RESULTS

All patients were women. We identified five patients with comorbid CTDs (3.3%): Sjögren's syndrome (SjS) (n = 3), systemic lupus erythematosus (n = 1), and rheumatoid arthritis (n = 1). One patient with SjS was also diagnosed with antiphospholipid antibody syndrome. The positive rate for anti nuclear antibody was 31.5% and 6.9% at dilution of 1:40 or higher, and those of 1:160 or higher, respectively.  It tended to be lower in patients with LAM than in healthy women. The positive rate for anti-SS-A and anti-SS-B antibody was 7.9% and 1.8%, respectively. No significant differences in age, type of LAM, smoking status, serum vascular endothelial growth factor D level, respiratory function, treatment, or prognosis were observed among the three groups.

CONCLUSIONS

Comorbid CTDs, especially SjS, in LAM patients should be considered.

Comparison of corneal biomechanical properties of patients with dry eye secondary to Sjögren's syndrome and healthy subjects

PURPOSE

The goal of this study is to determine whether any difference in corneal biomechanical properties exists between Sjögren's syndrome dry eye patients and healthy subjects.

METHODS

Thirty-one patients diagnosed with Sjögren's syndrome and associated dry eye manifestations and 44 healthy individuals were included in the study. Ultrasonic pachymetry (UP) was used to measure central corneal thickness (CCT). Corneal biomechanical parameters were obtained using ocular response analyzer (ORA). The main parameters assessed were corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann correlated intraocular pressure (IOPg) and corneal compensated IOP (IOPcc). A Student's t-test for independent groups was performed to compare the mean of these variables between both groups.

RESULTS

Mean CH values in Sjögren's syndrome and healthy subject eyes were 10.1mmHg and 11.18mmHg respectively, representing a statistically significant difference (P=0.003). No other variable measured differed between cases and controls (P>0.05). Mean CRF values were 9.51mmHg and 10.37mmHg respectively, and mean CCT measured by UP in cases and controls was 527.41μm and 552.51μm respectively.

CONCLUSIONS

Sjögren's syndrome can influence corneal biomechanical properties, specifically CH. ORA measurements should be considered of interest in the evaluation of Sjögren syndrome subjects.

The role of RORα in salivary gland lesions in patients with primary Sjögren's syndrome

Background

The orphan nuclear receptors retinoic acid-related receptor α and γt (RORα and RORγt) are critical in the development of T helper 17 (Th17) cells, and ROR-specific synthetic ligands have proven efficacy in several mouse models of autoimmunity. However, the pathological significance of RORα in primary Sjögren’s syndrome (pSS) remains to be elucidated. The present study was designed to clarify the significance of RORα in the pathogenesis of pSS.

Methods

RORα expression in the labial salivary gland (LSG) was determined by immunohistochemical analysis using a quantitative scoring system in 34 patients with pSS. The correlation between RORα expression in LSGs and the focus score (FS) was determined, and Th17 and IL-17 receptor A (1L-17RA) levels in LSGs were determined. To investigate the effect of RORs and the therapeutic potential of targeting RORs in pSS, we administered SR1001, a selective RORα/γt inverse agonist, to non-obese diabetic (NOD) mice.

Results

The expression of RORα was significantly increased in LSGs of patients with pSS and intensified with disease stage/FS, showing a similar increasing trend with IL-17A and IL-17RA. SR1001 significantly improved salivary gland secretory function and relieved sialadenitis in treated mice.

Conclusion

Our data reveal the importance of RORα in controlling pathologic lymphocytic infiltration of the salivary glands and suggest that RORα may be a druggable target in treating pSS.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1698-5) contains supplementary material, which is available to authorized users.

Calcium signaling defects underlying salivary gland dysfunction

Salivary glands secrete saliva, a mixture of proteins and fluids, which plays an extremely important role in the maintenance of oral health. Loss of salivary secretion causes a dry mouth condition, xerostomia, which has numerous deleterious consequences including opportunistic infections within the oral cavity, difficulties in eating and swallowing food, and problems with speech. Saliva secretion is regulated by stimulation of specific signaling mechanisms within the acinar cells of the gland. Neurotransmitter-stimulated increase in cytosolic [Ca²⁺] ([Ca²⁺]_i) in acinar cells is the primary trigger for salivary fluid secretion from salivary glands, the loss of which is a critical factor underlying dry mouth conditions in patients. The increase in [Ca²⁺]_i regulates multiple ion channel and transport activities that together generate the osmotic gradient which drives fluid secretion across the apical membrane. Ca²⁺ entry mediated by the Store-Operated Ca²⁺ Entry (SOCE) mechanism provides the essential [Ca²⁺]_i signals to trigger salivary gland fluid secretion. Under physiological conditions depletion of ER-Ca²⁺ stores is caused by activation of IP3R by IP3 and this provides the stimulus for SOCE. Core components of SOCE in salivary gland acinar cells are the plasma membrane Ca²⁺ channels, Orai1 and TRPC1, and STIM1, a Ca²⁺-sensor protein in the ER, which regulates both channels. In addition, STIM2 likely enhances the sensitivity of cells to ER-Ca²⁺ depletion thereby tuning the cellular response to agonist stimulation. Two major, clinically relevant, conditions which cause irreversible salivary gland dysfunction are radiation treatment for head-and-neck cancers and the autoimmune exocrinopathy, Sjögren's syndrome (pSS). However, the exact mechanism(s) that causes the loss of fluid secretion, in either condition, is not clearly understood. A number of recent studies have identified that defects in critical Ca²⁺ signaling mechanisms underlie salivary gland dysfunction caused by radiation treatment or Sjögren's syndrome (pSS). This chapter will discuss these very interesting and important studies.

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.

Significance of Interleukin-6/STAT Pathway for the Gene Expression of REG Iα, a New Autoantigen in Sjögren's Syndrome Patients, in Salivary Duct Epithelial Cells

The regenerating gene, Reg, was originally isolated from a rat regenerating islet complementary DNA (cDNA) library, and its human homologue was named REG Iα. Recently, we reported that REG Iα messenger RNA (mRNA), as well as its product, was overexpressed in ductal epithelial cells in the salivary glands of Sjögren's syndrome patients. Furthermore, autoantibodies against REG Iα were found in the sera of Sjögren's syndrome patients, and the patients who were positive for the anti-REG Iα antibody showed significantly lower saliva secretion than antibody-negative patients. We found the mechanism of REG Iα induction in salivary ductal epithelial cells. Reporter plasmid containing REG Iα promoter (-1190/+26) upstream of a luciferase gene was introduced into human NS-SV-DC and rat A5 salivary ductal cells. The cells were treated with several cytokines (interleukin (IL)-6, IL-8, etc.), upregulated in Sjögren's syndrome salivary ducts, and the transcriptional activity was measured. IL-6 stimulation significantly enhanced the REG Iα promoter activity in both cells. Deletion analysis revealed that the -141∼-117 region of the REG Iα gene was responsible for the promoter activation by IL-6, which contains a consensus sequence for signal transducer and activator of transcription (STAT) binding. The introduction of small interfering RNA for human STAT3 abolished IL-6-induced REG Iα transcription. These results indicated that IL-6 stimulation induced REG Iα transcription through STAT3 activation and binding to the REG Iα promoter in salivary ductal cells. This dependence of REG Iα induction upon IL-6/STAT in salivary duct epithelial cells may play an important role in the pathogenesis/progression of Sjögren's syndrome.

A spatial gradient of bacterial diversity in the human oral cavity shaped by salivary flow

Spatial and temporal patterns in microbial communities provide insights into the forces that shape them, their functions and roles in health and disease. Here, we used spatial and ecological statistics to analyze the role that saliva plays in structuring bacterial communities of the human mouth using >9000 dental and mucosal samples. We show that regardless of tissue type (teeth, alveolar mucosa, keratinized gingiva, or buccal mucosa), surface-associated bacterial communities vary along an ecological gradient from the front to the back of the mouth, and that on exposed tooth surfaces, the gradient is pronounced on lingual compared to buccal surfaces. Furthermore, our data suggest that this gradient is attenuated in individuals with low salivary flow due to Sjögren's syndrome. Taken together, our findings imply that salivary flow influences the spatial organization of microbial communities and that biogeographical patterns may be useful for understanding host physiological processes and for predicting disease.

Reduced myofilament component in primary Sjögren's syndrome salivary gland myoepithelial cells

Primary Sjögren's syndrome (pSS) is a solitary poorly understood autoimmune inflammatory disease by involvement of the salivary and lacrimal glands resulting in dry mouth and dry eyes. Myoepithelial cells (MECs) are cells knowing for its hybrid epithelial and mesenchymal phenotype that are important components of the salivary gland (SGs) structure aiding the expulsion of saliva from acinar lobules. In this study we investigate possible alteration in the myofilament component of MECs in SGs specimens obtained from pSS patients in comparison with healthy subjects, to evaluate MECs hypothetical involvement in the pathogenesis of pSS. The expression of alpha-smooth muscle actin (α-SMA) and p63, as MECs markers, was evaluated in bioptic specimens from pSS and healthy labial SGs through immunohistochemistry and immunofluorescence analyses; the distribution of MECs markers was quantified using Aperio ScanScope and ImageScope software to provide quantitative assessments of staining levels. Our observations demonstrated that p63 nuclear labeling in pSS MECs is preserved whereas α-SMA cytoplasmic staining is strongly and significantly reduced when compared with healthy SGs; the digital images analysis quantification of the expression of labeled α-SMA and p63 protein in the healthy and pSS MECs salivary tissues, led to results suggesting a loss of mechanical support for acini and ducts in pSS, correlated, probably, with the reduction of salivary flow that features one important aspect of pSS disease.

Detection of autoantibodies against aquaporin-5 in the sera of patients with primary Sjögren's syndrome

The pathophysiology of exocrine dysfunction observed in Sjögren's syndrome (SS) is not fully understood. The purpose of this study was to investigate whether autoantibodies against human AQP5 are present in the sera of SS patients. Frozen sections of mouse submandibular salivary glands, CHO cells over-expressing a human AQP5-GFP fusion protein or GFP, and MDCK cells over-expressing AQP5 were used in the indirect immunofluorescence assay to detect anti-AQP5 autoantibodies in the sera from patients with primary SS. The lysates of HEK-293 cells over-expressing the AQP5-GFP fusion protein or GFP were used for immunoprecipitation. Serum IgG from the SS patients but not from the control subjects stained acinar cells in the mouse salivary glands, the signals of which colocalized with those of AQP5-specific antibodies. Serum IgG from the SS patients also selectively stained AQP5-GFP expressed in CHO cells. However, both the control and SS sera immunoprecipitated the AQP5-GFP, suggesting that autoantibodies against AQP5 were also present in the control sera. The screening of 53 control and 112 SS samples by indirect immunofluorescence assay using the AQP5-expressing MDCK cells revealed the presence of significantly higher levels of anti-AQP5 IgG in the SS samples than in the control samples with sensitivity of 0.73 and a specificity of 0.68. Furthermore, the presence of anti-AQP5 autoantibodies was associated with low resting salivary flow in SS patients. In conclusion, anti-AQP5 autoantibodies were detected in the sera from SS patients, which could be a novel biomarker of SS and provide new insight into the pathogenesis of SS.

TFOS DEWS II Sex, Gender, and Hormones Report

One of the most compelling features of dry eye disease (DED) is that it occurs more frequently in women than men. In fact, the female sex is a significant risk factor for the development of DED. This sex-related difference in DED prevalence is attributed in large part to the effects of sex steroids (e.g. androgens, estrogens), hypothalamic-pituitary hormones, glucocorticoids, insulin, insulin-like growth factor 1 and thyroid hormones, as well as to the sex chromosome complement, sex-specific autosomal factors and epigenetics (e.g. microRNAs). In addition to sex, gender also appears to be a risk factor for DED. "Gender" and "sex" are words that are often used interchangeably, but they have distinct meanings. "Gender" refers to a person's self-representation as a man or woman, whereas "sex" distinguishes males and females based on their biological characteristics. Both gender and sex affect DED risk, presentation of the disease, immune responses, pain, care-seeking behaviors, service utilization, and myriad other facets of eye health. Overall, sex, gender and hormones play a major role in the regulation of ocular surface and adnexal tissues, and in the difference in DED prevalence between women and men. The purpose of this Subcommittee report is to review and critique the nature of this role, as well as to recommend areas for future research to advance our understanding of the interrelationships between sex, gender, hormones and DED.

Is hydroxychloroquine effective in treating primary Sjogren's syndrome: a systematic review and meta-analysis

BACKGROUND

To systematically review and assess the efficacy and safety of hydroxychloroquine (HCQ) for treating primary Sjogren's syndrome (pSS).

METHODS

Five electronic databases (Pubmed, EMBASE, Web of science, Ovid, Cochrane Library) were searched for randomized controlled trials and retrospective or prospective studies published in English that reported the effect of HCQ on pSS. The subjective symptoms (sicca symptoms, fatigue and pain) and the objective indexes (erythrocyte sedimentation rate and Schirmer test) were assessed as main outcome measures. A meta-analysis and descriptive study on the efficacy and safety of HCQ were conducted. The estimate of the effect of HCQ treatment was expressed as a proportion together with 95% confidence interval, and plotted on a forest plot.

RESULTS

Four trials with totals of 215 SS patients, including two randomized controlled trials, one double blind crossover trial and one retrospective open-label study, were analyzed in this review. For dry mouth and dry eyes, the effectiveness of HCQ treatment was essentially the same as placebo treatment. For fatigue, the effectiveness of HCQ was lower than placebo. The efficacy of HCQ in treating pain associated with pSS was superior to that of the placebo. There was no significant difference between HCQ-treated groups and controls in terms of Schirmer test results, but HCQ could reduce the erythrocyte sedimentation rate compare with placebo. A descriptive safety assessment showed that gastrointestinal adverse effects were the most common adverse effects associated with HCQ.

CONCLUSIONS

This systematic review showed that there is no significant difference between HCQ and placebo in the treatment of dry mouth and dry eye in pSS. Well-designed, randomized, controlled trials are needed to provide higher-quality evidence to confirm our findings, and future studies should focus on some other index or extraglandular measures, such as cutaneous manifestations, to further explore the therapeutic effect of HCQ in pSS.

Significance and Implications of Patient-reported Xerostomia in Sjögren's Syndrome: Findings From the National Institutes of Health Cohort

Background

Xerostomia is a chief complaint of patients with Sjögren's syndrome (SS). However, newer proposals for SS classification remove xerostomia and hyposalivation from the criteria list. Given these developments and the importance of patient-centered research outcomes, we sought to evaluate the utility of patient-reported xerostomia with implications for classification criteria, and clinical trials targeting SS treatment modalities.

Methods

A nested case-control study was designed within The National Institute of Dental and Craniofacial Research/National Institutes of Health (NIDCR/NIH) SS Cohort - one of the largest SS cohorts in the US. Clinical characteristics of those with and without xerostomia in SS and other salivary gland dysfunctions were compared. Several analytical methods were employed, including multivariable logistic regression modeling.

Findings

The NIDCR/NIH Sjögren's Syndrome Clinic has an open cohort with ongoing enrollment since 1984. This open cohort comprised of 2046 participants by August 27, 2015. Baseline data of 701 SS, 355 Sicca, and 247 ISS participants within the source cohort were analyzed. Xerostomia was highest among SS participants (87.4%, 95% CI: 84.8%–89.8%) compared to Sicca (72.4%, 95% CI: 67.4%–77.0%, p < 0.001) and ISS groups (38.1%, 95% CI: 32.0%–44.4%, p < 0.001). Those with xerostomia were more likely to have SS than Sicca/ISS (OR = 4.98, 95% CI: 3.78–6.56). The ability of xerostomia to screen for SS among those with salivary gland dysfunction was higher than screening for Sicca/ISS. Screening diagnostics of xerostomia were of greater utility compared to hyposalivation. After adjusting for confounding in multivariable modeling, SS participants with xerostomia were more likely to be White (Black/African Americans (OR: 0.40, 95% CI: 0.23–0.68, p-value = 0.001) and Asians (OR: 0.49, 95% CI: 0.25–0.96, p-value = 0.038) were less likely to have xerostomia compared to Whites), have dry eye symptoms for > 3 months (OR: 5.80, 95% CI: 3.62–9.28, p-value < 0.001), a lower Van Bijsterveld score (OR: 0.55, 95%CI: 0.34–0.90, p-value = 0.017), a lower stimulated salivary flow rate (OR: 1.67, 95% CI: 1.06–2.65, p-value = 0.028), a focus score of > 2 (OR: 1.92, 95% CI: 1.20–3.09, p-value = 0.007), and salivary gland swelling (OR: 49.39, 95% CI: 2.02–1206.30, p-value = 0.017). Age, gender, fatigue, pain, anxiety, and autoantibodies were not significantly associated with xerostomia.

Interpretation

Findings from this study indicate that patient-reported xerostomia is highly prevalent among SS patients and is associated with several clinical phenotypes of this complex syndrome, thereby making it an important indicator of SS. The evidence also suggests that xerostomia is not limited to low salivary flow but might be reflective of compositional changes of saliva. Consequently, these findings suggest the need to consider xerostomia in the development of SS classification criteria and in patient-centered outcomes research in SS intervention trials.

This research was supported by the Intramural Research Program of the National Institutes of Health (NIH), National Institute of Dental and Craniofacial Research (NIDCR) Grant # DE000704-15. Dr. Baer is supported by RO1-DE-12354-15A1.

•

Xerostomia is highly prevalent among SS patients and is associated with several clinical characteristics of SS.

•

Test diagnostics of xerostomia and other findings indicate that xerostomia is an important indicator of SS.

•

Findings of the study have implications for SS classification systems and SS intervention trials.

Research in Context

Data on the prevalence of xerostomia/dry mouth in SS are lacking, despite it being a chief complaint of patients. SS is a complex autoimmune disorder that is defined on the basis of classification criteria. There is ongoing debate on the selection of criteria and a consensus has not yet been reached by the scientific community. There is push to eliminate both xerostomia and hyposalivation, an objective sign of low salivary flow, from SS classification. This study offers evidence on the importance of xerostomia with implications for SS classification. Clinical trials to test newer treatment modalities for SS use classification criteria to define an SS case. Therefore, classification criteria are critical for research and advancement of newer therapeutics for SS. Xerostomia should be targeted as a patient-centered research outcome in SS intervention trials.