Lactate-induced mtDNA Accumulation Activates cGAS-STING Signaling and the Inflammatory Response in Sjögren's Syndrome

Acinar epithelial cell atrophy in secretory glands is a hallmark of primary Sjögren's syndrome (pSS), the cause of which is far from elucidated. We examined the role of acinar atrophy by focusing on the metabolism of glandular epithelial cells and mitochondria in the pSS environment. After confirming the presence of a high-lactate environment in the labial glands of human pSS patients, we used the A253 cell line and NOD/Ltj mice as models to investigate the metabolic changes in salivary gland epithelial cells in a high-lactate environment in vitro and in vivo. We found that epithelial cells produced high levels of IL-6, IL-8, IFN-α, IFN-β and TNF-α and exhibited significant NF-κB and type I IFN-related pathway activation. The results confirmed that lactate damaged mitochondrial DNA (mtDNA) and led to its leakage, which subsequently activated the cGAS-STING pathway. Inflammatory cytokine production and pathway activation were inhibited in vivo and in vitro by the lactate scavenger sodium dichloroacetate (DCA). Our study provides new insights into the etiology and treatment of pSS from the perspective of cell metabolism.

Multiple fibrotic lung nodules in a patient with primary Sjögren's syndrome

Evaluation of bilateral lung nodules noted on imaging poses a diagnostic challenge to clinicians as it can have many differentials from benign to malignant causes. It becomes especially critical to identify them right when there are underlying autoimmune conditions and risk factors for infection. However, a thorough investigation can lead to the recognition of rare associations as described below. We present here a 57-year-old woman who was admitted to the hospital with shortness of breath. Imaging with a computed tomography (CT) scan showed that she had 8 bilateral cystic pulmonary nodules with focal areas of ground-glass opacity and mediastinal lymphadenopathy. Fibrobronchoscopy and histopathological studies were done on the right middle lobe lung nodule demonstrated that the lung nodule was fibrotic with reactive inflammation but showed no malignant cells. Upon further detailed history and chart review, it was noted that the patient had a history of dry eyes leading to an autoimmune workup showing positive antinuclear antibodies (ANA), anti-Ro, and anti-La antibodies with no follow-up since then. This lead to the suspicion that these nodules could be related to underlying Sjögren's syndrome. Initial inpatient management with intravenous steroids showed significant improvement in her symptomatology. Hence, we present this rare association of lung nodules with Sjögren's syndrome and its management for awareness of this condition.

An Update on the Lived Experience of Dry Mouth in Sjögren's Syndrome Patients

This paper aims to provide an update on research findings on the lived experience of dry mouth in Sjögren's Syndrome (SS) patients. Dry mouth is a significant condition that impacts on the daily lives of people with SS. There will first be a summary of the definition, etiology, and manifestation of dry mouth in SS patients. There will next be an overview of the measurement of the impact of dry mouth on the quality of life in SS patients. This will include a deliberation of both quantitative and qualitative methods. Lastly, there will be discussion on the consequences of dry mouth, with a focus on qualitative studies that seek to understand patients' physical, emotional, and social domains of life.

The Prevalence of Sjögren's Syndrome in Rheumatoid Arthritis Patients and Their Clinical Features

BACKGROUND

To estimate the prevalence of Sjögren's syndrome (SS) in patients with rheumatoid arthritis (RA) and to compare the clinical features of RA patients with and without SS.

METHODS

We conducted a retrospective study of RA patients who visited a rheumatology clinic in a tertiary referral hospital in Korea between May 20 and July 22, 2016. All patients fulfilled the classification criteria for RA, and the diagnosis of SS was made clinically by rheumatologists and according to the 2002 American-European Consensus Group (AECG), 2012 American College of Rheumatology (ACR), and 2016 ACR/European League Against Rheumatism (EULAR) classification criteria. The prevalence was estimated as the number of SS patients within the total number of RA patients. The disease activity and treatment pattern of RA were compared between patients with and without SS.

RESULTS

Among 827 RA patients, 72 patients (8.7%) were diagnosed with SS by a rheumatologist, though only 60 patients (7.3%) satisfied the 2002 AECG classification criteria for SS. Fifty-two patients (6.3%) and 56 patients (6.8%) fulfilled the 2012 ACR and 2016 ACR/EULAR classification criteria, respectively. The prevalence of SS in RA patients was 10.5%, 17.0%, and 67.6% in rheumatoid factor, antinuclear antibody (≥ 1:80), and anti-Ro antibody positive patients, respectively.

CONCLUSION

The prevalence of SS among RA patients was 8.7% according to rheumatologists' diagnosis. The presence of SS did not affect the treatment patterns of RA patients. However, the autoantibody profiles and demographics of RA patients with SS differed from those of patients without SS.

Small RNA Deep Sequencing Identifies a Unique miRNA Signature Released in Serum Exosomes in a Mouse Model of Sjögren's Syndrome

Sjögren's Syndrome (SS) is an autoimmune disease characterized by lymphocytic infiltration and loss of function of moisture-producing exocrine glands as well as systemic inflammation. SS diagnosis is cumbersome, subjective and complicated by manifestation of symptoms that overlap with those of other rheumatic and ocular diseases. Definitive diagnosis averages 4–5 years and this delay may lead to irreversible tissue damage. Thus, there is an urgent need for diagnostic biomarkers for earlier detection of SS. Extracellular vesicles called exosomes carry functional small non-coding RNAs which play a critical role in maintaining cellular homeostasis via transcriptional and translational regulation of mRNA. Alterations in levels of specific exosomal miRNAs may be predictive of disease status. Here, we have assessed serum exosomal RNA using next generation sequencing in a discovery cohort of the NOD mouse, a model of early-intermediate SS, to identify dysregulated miRNAs that may be indicative of SS. We found five miRNAs upregulated in serum exosomes of NOD mice with an adjusted p < 0.05—miRNA-127-3p, miRNA-409-3p, miRNA-410-3p, miRNA-541-5p, and miRNA-540-5p. miRNAs 127-3p and 541-5p were also statistically significantly upregulated in a validation cohort of NOD mice. Pathway analysis and existing literature indicates that differential expression of these miRNAs may dysregulate pathways involved in inflammation. Future studies will apply these findings in a human cohort to understand how they are correlated with manifestations of SS as well as understanding their functional role in systemic autoimmunity specific to SS.

Recent advances in the search for a targeted immunomodulatory therapy for primary Sjögren's syndrome

Primary Sjögren's syndrome is a chronic autoimmune disease characterized by salivary and lacrimal gland dysfunction, leading to substantial morbidity and reduced quality of life. Many patients with primary Sjögren's syndrome also have extraglandular systemic complications, some of which can be organ- or life-threatening. Over the last decade, numerous targeted immunomodulatory therapies for primary Sjögren's syndrome have failed to show a benefit in clinical trials, and as yet no disease-modifying therapy has been approved for this disease. Herein, we provide an updated review of the clinical trial landscape for primary Sjögren's syndrome and the numerous efforts to move the field forward, including the development of new classification criteria and outcome measures, the results of recent clinical trials in this field, the challenges faced in the search for effective therapies, and the expanding pipeline of novel therapies under development.

Ly9 (CD229) Antibody Targeting Depletes Marginal Zone and Germinal Center B Cells in Lymphoid Tissues and Reduces Salivary Gland Inflammation in a Mouse Model of Sjögren's Syndrome

Sjögren's Syndrome (SjS) is a common chronic autoimmune disease characterized by the B cell hyperactivation, lymphocyte infiltration, and tissue damage of exocrine glands. It can also present life-threatening extraglandular manifestations, such as pulmonary and hepatic involvement, renal inflammation and marginal zone (MZ) B cell lymphoma. Several biologic agents have been tested in SjS but none has shown significant efficacy. Here, we report the effects of Ly9 (CD229) antibody targeting, a cell surface molecule that belongs to the SLAM family of immunomodulatory receptors, using NOD.H-2^h4 mice as a model of SjS-like disease. Female mice were treated with anti-Ly9 antibody or isotype control at week 24, when all mice present SjS related autoantibodies, salivary gland infiltrates, and marginal zone (MZ) B cell pool enlargement. Antibody injection depleted key lymphocyte subsets involved in SjS pathology such as MZ, B1, and germinal center B cells in spleen and draining lymph nodes without inducing a general immunosuppression. Importantly, mice receiving anti-Ly9 mAb showed a reduced lymphocyte infiltrate within salivary glands. This reduction may be, in part, explained by the down-regulation of L-selectin and alfa4/beta7 integrin induced by the anti-Ly9 antibody. Furthermore, levels of anti-nuclear autoantibodies were reduced after anti-Ly9 treatment. These data indicate that Ly9 is a potential therapeutic target for the treatment of SjS.

A novel elastin-like polypeptide drug carrier for cyclosporine A improves tear flow in a mouse model of Sjögren's syndrome

As a potent macrolide immunosuppressant, cyclosporine A (CsA) is used to treat multiple autoimmune diseases, including non-autoimmune and autoimmune-mediated dry eye disease, rheumatoid arthritis and psoriasis. Despite its potency, CsA has poor solubility, poor bioavailability, and can cause serious adverse reactions such as nephrotoxicity and neurotoxicity. To overcome these limitations, we invented a new strategy to carry CsA by fusing its cognate human receptor, cyclophilin A (CypA), to a 73 kDa elastin-like polypeptide (ELP) termed A192 using recombinant protein expression. Derived from human tropoelastin, ELPs are characterized by the ability to phase separate above a temperature that is a function of variables including concentration, molecular weight, and hydrophobicity. The resultant fusion protein, termed CA192, which assembles into a dimeric species in solution, effectively binds and solubilizes CsA with a K_d of 189 nM, comparable to that of endogenous CypA with a K_d of 35.5 nM. The release profile of CsA from CA192 follows a one phase decay model with a half-life of 957.3 h without a burst release stage. Moreover, CA192-CsA inhibited IL-2 expression induced in Jurkat cells through the calcineurin-NFAT signaling pathway with an IC₅₀ of 1.2 nM, comparable to that of free CsA with an IC₅₀ of 0.5 nM. The intravenous pharmacokinetics of CA192 followed a two-compartment model with a mean residence time of 7.3 h. Subcutaneous administration revealed a bioavailability of 30% and a mean residence time of 15.9 h. When given subcutaneously for 2 weeks starting at 14 weeks in male non-obese diabetic (NOD) mice, a model of autoimmune dacryoadenitis used to study Sjögren's syndrome (SS), CA192-CsA (2.5 mg/kg, every other day) significantly (p = 0.014) increased tear production relative to CA192 alone. Moreover, CA192 delivery reduced indications of CsA nephrotoxicity relative to free CsA. CA192 represents a viable new approach to deliver this effective but nephrotoxic agent in a modality that preserves therapeutic efficacy but suppresses drug toxicity.

Corneal confocal microscopy alterations in Sjögren's syndrome dry eye

PURPOSE

To evaluate light backscattering (LB) in corneal layers in patients with primary Sjögren's syndrome dry eye (SSDE) utilizing in vivo corneal confocal microscopy (IVCM) and to determine the eventual association with the lacrimal functional test values.

METHODS

A complete ophthalmic evaluation, Schirmer test with and without stimulation, break-up time (BUT) and IVCM were performed on 55 patients affected by SSDE and in an age- and sex-matched cohort of healthy participants (HP). Light backscattering, measures as light reflectivity unit (LRU), detected by IVCM at Bowman's membrane (BM) at 50 μm, at 100 μm and at 200 μm deeper than BM was compared in the two groups. The correlations between LB values and lacrimal function results were evaluated.

RESULTS

In patients affected by SSDE, LB was significantly higher (p < 0.001) in each corneal layer examined (+14 ± 6.33 LRU at BM), compared with HP. A good reverse correlation between the light reflectivity measures at BM with Schirmer test with (r = -0.91) and without (r = -0.90) stimulation and BUT (r = -0.88) was found. Correlations were lower in the deeper corneal layers.

CONCLUSION

Even if our results should be confirmed in further studies with a larger population, these findings show that IVCM is a device able to detect alterations in corneal layers in SSDE patients related to the lacrimal function. Light backscattering (LB) could be very useful for clinical diagnosis and management of SSDE.

Characterizing Restorative Dental Treatments of Sjögren's Syndrome Patients Using Electronic Dental Records Data

Scant knowledge exists on the type of restorative treatments Sjögren's syndrome patients (SSP) receive in spite of their high dental disease burden due to hyposalivation. Increased adoption of electronic dental records (EDR) could help in leveraging information from these records to assess dental treatment outcomes in SSP. In this study, we evaluated the feasibility of using EDR to characterize the dental treatments SSP received and assess the longevity of implants in these patients. We identified 180 SSP in ten years of patients' data at the Indiana University School of Dentistry clinics. A total of 104 (57.77%) patients received restorative or endodontic treatments. Eleven patients received 23 implants with a survival rate of 87% at 40 months follow-up. We conclude that EDR data could be used for characterizing the treatments received by SSP and for assessing treatment outcomes.

Effect of Hydroxychloroquine Treatment on Dry Eyes in Subjects with Primary Sjögren's Syndrome: a Double-Blind Randomized Control Study

The effect of hydroxychloroquine (HCQ) on dry eye has not been fully determined. This study aimed to compare the 12-week efficacy of HCQ medication with that of a placebo in the management of dry eye in primary Sjögren's syndrome (pSS). A double-blind, randomized control study was conducted in 39 pSS subjects from May 2011 through August 2013. pSS was diagnosed based on the classification criteria of the American-European Consensus Group. Subjects received 300 mg of HCQ or placebo once daily for 12 weeks and were evaluated at baseline, 6, and 12 weeks, with a re-visit at 16 weeks after drug discontinuance. The fluorescein staining score, Schirmer test score, tear film break-up time (TBUT), and ocular surface disease index (OSDI) were measured, and tears and blood were collected for ESR, IL-6, IL-17, B-cell activating factor (BAFF), and Th17 cell analysis. Color testing was performed and the fundus was examined to monitor HCQ complications. Twenty-six subjects completed the follow-up. The fluorescein staining score and Schirmer test score did not differ significantly. The OSDI improved with medication in the HCQ group but was not significantly different between the groups. TBUT, serum IL-6, ESR, serum and tear BAFF, and the proportion of Th17 cells did not change in either group. HCQ at 300 mg daily for 12 weeks has no apparent clinical benefit for dry eye and systemic inflammation in pSS (ClinicalTrials.gov. NCT01601028).

Possible role of anti-SSA/Ro antibodies in the pathogenesis of pulmonary hypertension

INTRODUCTION

There are many different causes of pulmonary hypertension and the pathogenesis of the disease is still being elucidated. Although they are not the most common, autoimmunity and inflammation have been identified as possible causes. No one autoantibody has been identified as the definite cause of pulmonary hypertension. We present a rare association of anti-SSA/Ro antibodies and isolated pulmonary hypertension.

CASE PRESENTATION

A 53 year old African American female presented with abdominal pain, nausea, weight loss, dyspnea and fatigue. Upon further exam she was found to have high titers of antinuclear antibodies and anti-SSA/Ro antibodies. This antibody profile would typically be suggestive of Sjögren's Syndrome, which is characterized by dry eyes and poor salivary gland function. However, since this patient did not have any symptoms consistent with the disease a diagnosis of Sjögren's Syndrome could not be made. A combination of laboratory, imaging and diagnostic studies were done that revealed a final diagnosis of pulmonary hypertension.

CONCLUSION

It is known that pulmonary hypertension has association with autoimmune diseases, however no clear markers yet exist. Anti-SSA/Ro antibodies have been rarely described in cases of pulmonary disease, and less so in pulmonary hypertension. This case describes a unique association between isolated pulmonary hypertension and anti-SSA/Ro antibody, thereby illustrating the need to investigate this autoantibody and others in the pathogenesis of autoimmune pulmonary hypertension.

Imbalanced Rab3D versus Rab27 increases cathepsin S secretion from lacrimal acini in a mouse model of Sjögren's Syndrome

The mechanism responsible for the altered spectrum of tear proteins secreted by lacrimal gland acinar cells (LGAC) in patients with Sjögren's Syndrome (SS) remains unknown. We have previously identified increased cathepsin S (CTSS) activity as a unique characteristic of tears of patients with SS. Here, we investigated the role of Rab3D, Rab27a, and Rab27b proteins in the enhanced release of CTSS from LGAC. Similar to patients with SS and to the male nonobese diabetic (NOD) mouse model of SS, CTSS activity was elevated in tears of mice lacking Rab3D. Findings of lower gene expression and altered localization of Rab3D in NOD LGAC reinforce a role for Rab3D in suppressing excess CTSS release under physiological conditions. However, CTSS activity was significantly reduced in tears of mice lacking Rab27 isoforms. The reliance of CTSS secretion on Rab27 activity was supported by in vitro findings that newly synthesized CTSS was detected in and secreted from Rab27-enriched secretory vesicles and that expression of dominant negative Rab27b reduced carbachol-stimulated secretion of CTSS in cultured LGAC. High-resolution 3D-structured illumination microscopy revealed microdomains of Rab3D and Rab27 isoforms on the same secretory vesicles but present in different proportions on different vesicles, suggesting that changes in their relative association with secretory vesicles may tailor the vesicle contents. We propose that a loss of Rab3D from secretory vesicles, leading to disproportionate Rab27-to-Rab3D activity, may contribute to the enhanced release of CTSS in tears of patients with SS.

Illness Experiences in Women with Oral Dryness as a Result of Sjögren's Syndrome: The Patient Point of View

BACKGROUND

Sjögren's syndrome and the associated dryness can have multiple consequences. The aim of the present qualitative study was to give an in-depth account of the life experiences of women with primary Sjögren's syndrome (pSS) and health-related behaviours, and to summarize these experiences in an integrated model.

METHODS

Twelve women diagnosed with pSS who regularly attended the Hospital of the University of Chile participated in detailed interviews. The data were analysed using qualitative methods based on the principles of grounded theory.

RESULTS

Selective coding identified three categories: illness experience, social interaction and psychological response. An integrated model was developed connecting these dynamic aspects and suggesting how they could lead to a life cycle crisis in cases of maladjustment. We found that problem-solving strategies, reconstruction of identity, acceptance and a social support may prevent this life cycle crisis.

DISCUSSION

Xerostomia and other consequences of pSS can have a profound influence on daily life. However, the severity of the consequences depends on individual experiences with the illness, social influences and the psychological responses of the patient. Physicians, dentists and other healthcare professionals can help the patient by listening to their problems and exploring solutions based on a psychological approach.

Nebulized isotonic saline improves voice production in Sjögren's syndrome

OBJECTIVE

This study examined the effects of a topical vocal fold hydration treatment on voice production over time.

STUDY DESIGN

Prospective, longitudinal, within-subjects A (baseline), B (treatment), A (withdrawal/reversal), B (treatment) experimental design.

METHODS

Eight individuals with primary Sjögren's syndrome (SS), an autoimmune disease causing laryngeal dryness, completed an 8-week A-B-A-B experiment. Participants performed twice-daily audio recordings of connected speech and sustained vowels and then rated vocal effort, mouth dryness, and throat dryness. Two-week treatment phases introduced twice-daily 9-mL doses of nebulized isotonic saline (0.9% Na(+)Cl(-)). Voice handicap and patient-based measures of SS disease severity were collected before and after each 2-week phase. Connected speech and sustained vowels were analyzed using the Cepstral Spectral Index of Dysphonia (CSID). Acoustic and patient-based ratings during each baseline and treatment phase were analyzed and compared.

RESULTS

Baseline CSID and patient-based ratings were in the mild-to-moderate range. CSID measures of voice severity improved by approximately 20% with nebulized saline treatment and worsened during treatment withdrawal. Posttreatment CSID values fell within the normal-to-mild range. Similar patterns were observed in patient-based ratings of vocal effort and dryness. CSID values and patient-based ratings correlated significantly (P < .05).

CONCLUSION

Nebulized isotonic saline improves voice production based on acoustic and patient-based ratings of voice severity. Future work should optimize topical vocal fold hydration treatment formulations, dose, and delivery methodologies for various patient populations. This study lays the groundwork for future topical vocal fold hydration treatment development to manage and possibly prevent dehydration-related voice disorders.

LEVEL OF EVIDENCE

2b.

The SSB-positive/SSA-negative antibody profile is not associated with key phenotypic features of Sjögren's syndrome

OBJECTIVE

To determine whether the Sjögren's syndrome B (SSB)-positive/Sjögren's syndrome A (SSA)-negative antibody profile is associated with key phenotypic features of SS.

METHODS

Among registrants in the Sjögren's International Collaborative Clinical Alliance (SICCA) with possible or established SS, we compared anti-SSA/anti-SSB reactivity profiles against concurrent phenotypic features. We fitted logistic regression models to explore the association between anti-SSA/anti-SSB reactivity profile and each key SS phenotypic feature, controlling for potential confounders.

RESULTS

Among 3297 participants, 2061 (63%) had negative anti-SSA/anti-SSB, 1162 (35%) had anti-SSA with or without anti-SSB, and 74 (2%) anti-SSB alone. Key SS phenotypic features were more prevalent and had measures indicative of greater disease activity in those participants with anti-SSA, either alone or with anti-SSB, than in those with anti-SSB alone or negative SSA/SSB serology. These between-group differences were highly significant and not explained by confounding by age, race/ethnicity or gender. Participants with anti-SSB alone were comparable to those with negative SSA/SSB serology in their association with these key phenotypic features. Among SICCA participants classified with SS on the basis of the American-European Consensus Group or American College of Rheumatology criteria, only 2% required the anti-SSB-alone test result to meet these criteria.

CONCLUSIONS

The presence of anti-SSB, without anti-SSA antibodies, had no significant association with SS phenotypic features, relative to seronegative participants. The solitary presence of anti-SSB antibodies does not provide any more support than negative serology for the diagnosis of SS. This serological profile should thus be interpreted cautiously in clinical practice and potentially eliminated from future classification criteria.

EULAR Sjögren's syndrome disease activity index (ESSDAI): a user guide

The EULAR Sjögren's syndrome (SS) disease activity index (ESSDAI) is a systemic disease activity index that was designed to measure disease activity in patients with primary SS. With the growing use of the ESSDAI, some domains appear to be more challenging to rate than others. The ESSDAI is now in use as a gold standard to measure disease activity in clinical studies, and as an outcome measure, even a primary outcome measure, in current randomised clinical trials. Therefore, ensuring an accurate and reproducible rating of each domain, by providing a more detailed definition of each domain, has emerged as an urgent need. The purpose of the present article is to provide a user guide for the ESSDAI. This guide provides definitions and precisions on the rating of each domain. It also includes some minor improvement of the score to integrate advance in knowledge of disease manifestations. This user guide may help clinicians to use the ESSDAI, and increase the reliability of rating and consequently of the ability to detect true changes over time. This better appraisal of ESSDAI items, along with the recent definition of disease activity levels and minimal clinically important change, will improve the assessment of patients with primary SS and facilitate the demonstration of effectiveness of treatment for patients with primary SS.

Interaction between innate immunity and Ro52-induced antibody causes Sjögren's syndrome-like disorder in mice

OBJECTIVES

Autoantibodies reactive with Ro52 are often found in sera of patients with Sjögren's syndrome (SS). This study was undertaken to investigate the role of Ro52-induced immune responses in pathogenesis of SS.

METHODS

New Zealand Mixed (NZM) 2758 mice were immunised with Ro52 in alum adjuvant. Control mice were immunised either with maltose-binding protein or injected with alum alone. Mice were monitored for anti-Ro52 antibody, sialoadenitis and pilocarpine-induced salivation. Antibody binding to salivary gland (SG) cells was analysed in vivo and in vitro by immunofluorescence. Sera from immunised mice were passively transferred into untreated or alum injected NZM2758 mice.

RESULTS

By day 30 post-immunisation, Ro52 immunised mice generated immunoprecipitating anti-Ro52 antibodies and they had the maximum drop in saliva production. Both Ro52 immunised and control mice showed evidence of mild sialoadenitis. However, only Ro52 immunised mice had antibody deposition in their SG. Passive transfer of Ro52-immune sera induced SG dysfunction in recipient mice, only if the recipients were primed with alum. In vitro, antibodies from Ro52-immune sera were internalised by a SG cell line and this uptake was inhibited by cytochalasin D treatment.

CONCLUSIONS

Our data show for the first time that antibodies induced by Ro52 are capable of inducing SG dysfunction, and that this phenomenon is dependent on the activation of innate immunity. The mouse model described in this study implies that autoantibody deposition in the SG might be an important step in the induction of xerostomia and pathogenesis of SS.

Systemic activity and mortality in primary Sjögren syndrome: predicting survival using the EULAR-SS Disease Activity Index (ESSDAI) in 1045 patients

OBJECTIVE

To score systemic activity at diagnosis and correlate baseline activity with survival in a large cohort of patients with primary Sjögren syndrome (SS).

PATIENTS AND METHODS

We include 1045 consecutive patients who fulfilled the 2002 classification criteria for primary SS. The clinical and immunological characteristics and level of activity (EULAR-SS Disease Activity Index (ESSDAI) scores) were assessed at diagnosis as predictors of death using Cox proportional hazards regression analysis adjusted for age at diagnosis. The risk of death was calculated at diagnosis according to four different predictive models.

RESULTS

After a mean follow-up of 117 months, 115 (11%) patients died. The adjusted standardised mortality ratio for the total cohort was 4.66 (95% CI 3.85 to 5.60), and survival rates at 5, 10, 20 and 30 years were 96%, 90%, 81% and 60%, respectively. The main baseline factors associated with overall mortality in the multivariate analysis were male gender, cryoglobulins and low C4 levels. Baseline activity in the constitutional, pulmonary and biological domains was associated with a higher risk of death. High activity in at least one ESSDAI domain (HR 2.14), a baseline ESSDAI score ≥14 (HR 1.85) and more than one laboratory predictive marker (lymphopenia, anti-La, monoclonal gammopathy, low C3, low C4 and/or cryoglobulins) (HR 2.82) were associated with overall mortality; these HRs increased threefold to 10-fold when the analysis was restricted to mortality associated with systemic disease.

CONCLUSIONS

Patients with primary SS, who present at diagnosis with high systemic activity (ESSDAI ≥14) and/or predictive immunological markers (especially those with more than one), are at higher risk of death.

Calcium signaling and cell volume regulation are altered in Sjögren's Syndrome

OBJECTIVE

Sjögren's Syndrome (SS) is a chronic autoimmune disease, leading to deficient secretion from salivary and lacrimal glands. Saliva production is normally increased by cholinergic innervation, giving rise to intracellular calcium signaling and water transport through water channels (aquaporins, AQPs). The aim of this study was to investigate possible pathophysiological changes in cell volume regulation, AQP expression and localization, and intracellular calcium signaling in glandular cells from SS patients compared to controls.

MATERIALS AND METHODS

A total of 35 SS patients and 41 non-SS controls were included. Real time qPCR was combined with immunohistochemistry to analyze the mRNA expression and cellular distribution of AQP1, 3 and 5. Cell volume regulation and intracellular calcium signaling were examined in fresh acinar cells.

RESULTS

We show for the first time a reduced mRNA expression of AQP1 and 5 in SS compared to controls, accompanied by a decrease in staining intensity of AQP1, 3 and 5 in areas adjacent to local lymphocytic infiltration. Furthermore, we observed that the SS cells' capacity for volume regulation was abnormal. Similarly, the calcium response after parasympathetic agonist (carbachol) stimulation was markedly decreased in SS cells.

CONCLUSIONS

It is concluded that mRNA expression of AQP1 and 5, protein distribution of AQP1, 3 and 5, glandular cell volume regulation and intracellular calcium signaling are all altered in SS, pointing to possible pathophysiological mechanisms in SS.

Time course of cytokine upregulation in the lacrimal gland and presence of autoantibodies in a predisposed mouse model of Sjögren's Syndrome: the influence of sex hormones and genetic background

Sjögren's Syndrome (SS) is a chronic, inflammatory autoimmune disease characterized by lacrimal gland lymphocytic infiltration and epithelial cell death, as well as by the presence of serum autoantibodies. Although the symptoms of this syndrome are well characterized, patients are not diagnosed until 5-10 years into disease progression; furthermore, the early series of events leading to the initiation of SS are not well understood. In order to better understand the early events of the disease, we have been using ovariectomized (OVX) NOD.B10.H2(b) mice as a genetically predisposed model of SS. Previously, we have shown that removal of ovarian hormones through ovariectomy accelerated the symptoms of this disease, and in early events of SS in the lacrimal glands, lymphocytic infiltration preceded acinar cell apoptosis. To further elucidate the earlier events of this disease in the SS animal model, we investigated the expression and concentration of pro-inflammatory cytokines in the lacrimal glands as well as the presence of autoantibodies in both lacrimal glands and serum. Six weeks old NOD.B10.H2(b) and C57BL/10 control mice were either sham-operated, OVX, OVX and treated with 17β-estradiol (E2), or OVX and treated with dihydrotestosterone (DHT). Lacrimal glands were collected at 3, 7, 21, and 30 days after surgery and analyzed for cytokines IL-1β, TNF-α, IFN-γ, IL-10, and IL-4 gene expression by using quantitative RT-PCR and for cytokine levels using ELISA. Furthermore, anti-Ro/SSA and anti-La/SSB autoantibodies were measured in the serum and lacrimal glands supernatants using ELISA. The results of this study showed that OVX caused a significant increase in the expression and levels of the cytokines IL-1β, TNF-α, and IL-4 in the lacrimal glands of the NOD.B10.H2(b) mice starting at 3 days after OVX, while a significant increase of IL-10 gene expression and levels was observed only at later experimental time points. A small but significant increase in the expression of IL-1β and IL-4 was observed only at later experimental time points in the lacrimal glands of OVX C57BL/10 mice, while no significant changes in the expression of TNF-α and IL-10 were seen at any experimental times in this group. No significant differences were observed in the levels of the cytokines IL-1β, TNF-α, IL-4, and IL-10 in the lacrimal glands of the OVX C57BL/10 mice at any of the experimental times studied compared to the sham-operated group. IFN-γ was not detected in either mouse strains at the level of mRNA and protein. OVX in the NOD.B10.H2(b) mice also caused an increase in the levels of anti-Ro/SSA autoantibodies in the serum only, while no anti-La/SSB autoantibodies were found in the serum or lacrimal gland supernatants. Physiological doses of E2 or DHT at time of OVX prevented the upregulation of cytokines and the presence of anti-Ro/SSA autoantibodies in these animals. These results showed that a decrease in the concentrations of ovarian hormones in the genetically predisposed mice accelerated the onset of the disease by upregulating various pro-inflammatory cytokines at different time points and promoting the formation of anti-Ro/SSA serum autoantibodies, creating an environment favorable for the initiation of SS.

Epidemiology of primary Sjögren's syndrome: a systematic review and meta-analysis

OBJECTIVE

Epidemiological studies of primary Sjögren's syndrome (pSS) are crucial for describing the burden to society and the public medical system and for shedding light on aetiology. Previous reports of the epidemiology of pSS show variable outcomes. We conducted a systematic review of the epidemiology of pSS to assess the prevalence rates (PRs) and incidence rates (IRs), and to investigate possible geographic variations in pSS.

METHODS

A systematic literature search of PubMed and Embase (updated to 22 October 2013) was performed to identify all published reports on the epidemiology of pSS. The incidence and prevalence rates of pSS were summarised with IRs or PRs and 95% CIs.

RESULTS

The literature search yielded 1880 related citations. Only 21 fulfilled the inclusion criteria. According to a random-effects model, the pooled IR for pSS was 6.92 (95% CI 4.98 to 8.86) per 100 000 person-years. The overall PR was 60.82 (95% CI 43.69 to 77.94) cases per 100 000 inhabitants with a slightly lower estimate of Baodong Qin is BDQ, Jiaqi Wang is JQW, Zaixing Yang is ZXY, Renqian Zhong is RQZ. 43.03 (25.74 to 60.31) cases per 100 000 inhabitants when only considering population-based studies. The female/male ratio in incidence data was 9.15 (95% CI 3.35 to 13.18). The female/male ratio in prevalence data was 10.72 (95% CI 7.35 to 15.62). The overall age of pSS patients was 56.16 years (95% CI 52.54 to 59.78).

CONCLUSIONS

Incidence and prevalence rates of pSS vary widely around the world. The results help us better understand the global epidemiology of pSS. Large population-based studies combining meticulous case-finding and case-ascertainment strategies are needed.

Impact of the leucocyte immunoglobulin-like receptor A3 (LILRA3) on susceptibility and subphenotypes of systemic lupus erythematosus and Sjögren's syndrome

BACKGROUND

Recently, our research group identified the non-deleted (functional) leucocyte immunoglobulin-like receptor A3 (LILRA3) as a new genetic risk for rheumatoid arthritis.

OBJECTIVES

To further investigate whether the functional LILRA3 is a new susceptibility factor for other autoimmune diseases-for example, systemic lupus erythematosus (SLE) and primary Sjögren's syndrome (pSS).

METHODS

The LILRA3 deletion polymorphism and its tagging single nucleotide polymorphism rs103294 were genotyped for 1099 patients with SLE, 403 patients with pSS and 2169 healthy controls. Association analyses were performed in whole dataset or clinical/serological subsets. The impact of LILRA3 on SLE activity and LILRA3 expression was evaluated.

RESULTS

The functional LILRA3 conferred high susceptibility to both SLE (p=3.51×10(-7), OR=2.03) and pSS (p=1.40×10(-3), OR=2.32). It was associated with almost all the clinical/serological features in SLE, especially with leucopenia (p=4.09×10(-7), OR=2.19) and thrombocytopenia (p=1.68×10(-5), OR=1.70). In pSS, functional LILRA3 was specifically associated with leucopenia (p=4.39×10(-4), OR=3.25), anti-Ro/SSA-positive subphenotypes (p=4.54×10(-3), OR=2.34) and anti-La/SSB-positive subphenotypes (p=0.012, OR=2.49). Functional LILRA3 conferred higher disease activity in patients with SLE (p=0.044) and higher LILRA3 expression in both SLE (p=5.57×10(-8)) and pSS (p=1.49×10(-7)) than in controls.

CONCLUSIONS

Functional LILRA3 is a new susceptibility factor for SLE and pSS. It highly predisposes to certain phenotypes such as leucopenia and thrombocytopenia in SLE, and may confer increased disease activity in SLE and a higher risk of leucopenia and autoantibody-positive subphenotypes in pSS.

Proteomic analysis revealed the altered tear protein profile in a rabbit model of Sjögren's syndrome-associated dry eye

Sjögren's syndrome (SS) is an autoimmune disease that results in pathological dryness of mouth and eye. The diagnosis of SS depends on both clinical evaluation and specific antibodies. The goal of this study was to use quantitative proteomics to investigate changes in tear proteins in a rabbit model of SS-associated dry eye, induced autoimmune dacryoadenitis (IAD). Proteomic analysis was performed by iTRAQ and nano LC-MS/MS on tears collected from the ocular surface, and specific proteins were verified by high resolution MRM. It was found that in the tears of IAD rabbits at 2 and 4 weeks after induction, S100 A6, S100 A9, and serum albumin were upregulated, whereas serotransferrin (TF), prolactin-inducible protein (PIP), polymeric immunoglobulin receptor (pIgR), and Ig gamma chain C region were downregulated. High resolution MRM with mTRAQ labeling verified the changes in S100 A6, TF, PIP, and pIgR. Our results indicated significant changes of tear proteins in IAD rabbits, suggesting these proteins could potentially be used as biomarkers for the diagnosis and prognosis of dry eye. Several of these proteins were also found in the tears of non-SS dry eye patients indicating a common basis of ocular surface pathology, however, pIgR appears to be unique to SS.

Th17 cells play a critical role in the development of experimental Sjögren's syndrome

OBJECTIVE

Although Th17 cells have been increasingly recognised as an important effector in various autoimmune diseases, their function in the pathogenesis of Sjögren's syndrome (SS) remains largely uncharacterised. This study aims to determine the role of Th17 cells in the development of experimental SS (ESS).

METHODS

The ESS was induced in wildtype and IL-17A knockout (IL-17 KO) C57BL/6 mice immunised with salivary glands (SG) proteins. Phenotypic analysis of immune cells in the draining cervical lymph nodes (CLN) and SG was performed by flow cytometry and immunofluorescence microscopy. To determine the role of Th17 cells in ESS, immunised IL-17 KO mice were adoptively transferred with in vitro-generated Th17 cells and monitored for SS development. The salivary flow rate was measured, whereas inflammatory infiltration and tissue destruction in SG were assessed by histopathology.

RESULTS

SG protein-immunised mice developed overt SS symptoms with increased Th17 cells detected in CLN and within lymphocytic foci in inflamed SG. Notably, immunised IL-17 KO mice were completely resistant for SS induction, showing no evidence of disease symptoms and histopathological changes in SG. Adoptive transfer of Th17 cells rapidly induced the onset of ESS in immunised IL-17 KO mice with markedly reduced saliva secretion, elevated autoantibody production and pronounced inflammation and tissue damage in SG.

CONCLUSIONS

Our findings have defined a critical role of Th17 cells in the pathogenesis of ESS. Further studies may validate Th17 cell as a potential target for treating SS.

Potential involvement of the IL-33-ST2 axis in the pathogenesis of primary Sjogren's syndrome

OBJECTIVES

To investigate the role of the interleukin (IL)-33-ST2 axis in the pathophysiology of primary Sjögren's syndrome (pSS).

METHODS

Serum levels of IL-33 and sST2 were determined by ELISA. The expression of IL-33 and ST2 was investigated in salivary glands (SG) by immunohistochemistry. PBMC were isolated and stimulated with IL-33, IL-12 and IL-23 and the cytokine profile response was examined by flow cytometry. Intracellular cytokine detection of IFNγ and IL-17 was performed by flow cytometry.

RESULTS

Serum IL-33 and sST2 levels were increased in pSS patients compared with controls and patients with systemic lupus erythematosus. Expression of IL-33 was upregulated in SG with Chisholm scores of 2 and 3 of pSS patients but comparable with controls for SG with Chisholm score of 4. ST2 expression in SG was downregulated in pSS patients. IL-33 at different concentrations did not increase the secretion of pro-inflammatory cytokines but acted synergistically with IL-12 and IL-23 to promote IFNγ production. NK and NKT cells were identified as main producers of IFNγ in vitro and were found in SG of pSS patients.

CONCLUSIONS

IL-33 is released in pSS, and acts with IL-12 and IL-23 to favour the secretion of IFNγ by NK and NKT cells.

Subclinical reduced G6PD activity in rheumatoid arthritis and Sjögren's Syndrome patients: relation to clinical characteristics, disease activity and metabolic syndrome

OBJECTIVE

Glucose-6-phosphate dehydrogenase (G6PD) is an important site of metabolic control in the pentose phosphate pathway. The purpose of this study was to investigate the enzyme activity of G6PD in Rheumatoid Arthritis (RA) and Sjögren's Syndrome (SS) patients not known to be deficient in this enzyme. It was also within the scope of the aim to find the relation of G6PD to the presence of metabolic syndrome (MetS) in these patients.

METHODS

Erythrocyte G6PD activity was evaluated in 40 RA patients, 30 SS patients and in 30 age- and sex-matched control. The clinical characteristics, disease activity score (DAS28), SS disease activity (SSDAI) and damage (SSDDI) indices and presence of MetS of the included patients were analyzed in relation to the enzyme level.

RESULTS

The G6PD activity in RA patients (7.72 ± 3.57 U/g Hb) was significantly reduced compared to that in the SS patients (11.55 ± 3.14 U/g Hb) and control (13.23 ± 3.34 U/g Hb) especially those with MetS (4.61 ± 1.84 U/g Hb) (p < 0.001). There was a significant negative correlation of the G6PD activity with the disease duration and DAS28 (p < 0.001).

CONCLUSION

The results of this study, suggest that G6PD not only does not protect against MetS in RA, but may even be considered a risk factor for the development of this disorder. The identification of regulatory tools for G6PD activity may prove promising for treating the associated metabolic disorders and chronic inflammation in RA.

Potential role of human-specific genes, human-specific microRNAs and human-specific non-coding regulatory RNAs in the pathogenesis of systemic sclerosis and Sjögren's syndrome

The etiology and pathogenesis of human autoimmune diseases remain unknown despite intensive investigations. Although remarkable progress has been accomplished through genome wide association studies in the identification of genetic factors that may predispose to their occurrence or modify their clinical presentation to date no specific gene abnormalities have been conclusively demonstrated to be responsible for these diseases. The completion of the human and chimpanzee genome sequencing has opened up novel opportunities to examine the possible contribution of human specific genes and other regulatory elements unique to the human genome, such as microRNAs and non-coding RNAs, towards the pathogenesis of a variety of human disorders. Thus, it is likely that these human specific genes and non-coding regulatory elements may be involved in the development or the pathogenesis of various disorders that do not occur in non-human primates including certain autoimmune diseases such as Systemic Sclerosis and Primary Sjögren's Syndrome. Here, we discuss recent evidence supporting the notion that human specific genes or human specific microRNA and other non-coding RNA regulatory elements unique to the human genome may participate in the development or in the pathogenesis of Systemic Sclerosis and Primary Sjögren's Syndrome.

Electrolyte imbalances and nephrocalcinosis in acute phosphate poisoning on chronic type 1 renal tubular acidosis due to Sjögren's syndrome

Although renal calcium crystal deposits (nephrocalcinosis) may occur in acute phosphate poisoning as well as type 1 renal tubular acidosis (RTA), hyperphosphatemic hypocalcemia is common in the former while normocalcemic hypokalemia is typical in the latter. Here, as a unique coexistence of these two seperated clinical entities, we report a 30-yr-old woman presenting with carpal spasm related to hypocalcemia (ionized calcium of 1.90 mM/L) due to acute phosphate poisoning after oral sodium phosphate bowel preparation, which resolved rapidly after calcium gluconate intravenously. Subsequently, type 1 RTA due to Sjögren's syndrome was unveiled by sustained hypokalemia (3.3 to 3.4 mEq/L), persistent alkaline urine pH (> 6.0) despite metabolic acidosis, and medullary nephrocalcinosis. Through this case report, the differential points of nephrocalcinosis and electrolyte imbalances between them are discussed, and focused more on diagnostic tests and managements of type 1 RTA.

Extraordinary antigenicity of the human Ro52 autoantigen

Autoantibody levels to the SSA complex, composed of Ro52 and Ro60 proteins, are commonly measured in the diagnoses of Sjögren's Syndrome (SjS), as well as other rheumatological diseases. One of these proteins, Ro52, is an interferon-inducible member of the tripartite motif family bearing a RING motif functioning as an E3 ligase that ubiquitinates interferon regulatory factor 8 and other proteins. Using Luciferase Immunoprecipitation Systems (LIPS) we explored the antigenicity of Ro52 in detail. Analysis of antibody responses against Ro52 and 20 other established antigens revealed that Ro52 had the highest antibody titers and most likely represents one of the most immunogenic human proteins. While the antibody titers in many of the SjS patients were significantly and substantially higher than the controls, all healthy individuals had anti-Ro52 autoantibodies. N- and C-terminal fragments of Ro52 showed immunoreactivity in these serum samples, but the sums of these antibody titers were significantly lower than the antibody titers directed against the full-length Ro52. Antibody profiling of controls and SjS patients with three different N-terminal fragments of Ro52 revealed that the coiled-coil region was the most useful diagnostic (66% sensitivity), followed by the B-box (31% sensitivity), and then the RING-finger (24% sensitivity). The C-terminal region of Ro52, containing the B30.2 domain, showed higher antibody titers in SjS patients compared to controls and this region was responsible for the high level of Ro52 immunoreactivity in healthy individuals. Analysis of immunoreactivity to TRIM5, a Ro52-related protein, and the B30.2 domain from BTN1 and pyrin, failed to show significant antibody titers with the control or SjS patient serum. These results highlight the unusually high level of Ro52 antigenicity and demonstrate that autoantibodies are directed at both linear and conformational epitopes spanning the entire molecule.