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Background Mononuclear cell infiltration of exocrine glands, production of Ro/SSA and La/SSB autoantibodies, along with oral and ocular dryness, are characteristic features of primary Sjögren’s syndrome (pSS). Non-SS sicca subjects, an underexplored group in relation to pSS, display similar sicca symptoms, with possible mild signs of inflammation in their salivary glands, yet with no serological detection of autoantibody production. In this study, we investigated inflammatory manifestations in the salivary gland tissue, tear fluid and saliva of non-SS subjects, as compared to pSS patients and healthy individuals. Methods Fifteen non-SS, 10 pSS and 10 healthy subjects were included in the analyses. Histological evaluation of salivary gland biopsies was performed. Liquid chromatography-mass spectrometry (LC-MS) was conducted on tear fluid and stimulated whole saliva, and proteomic biomarker profiles were generated. Extracellular vesicle (EVs) isolation and characterisation from both fluids were also combined with LC-MS. The LC-MS data were analysed for quantitative differences between patient and control groups using Scaffold. Database for Annotation, Visualization and Integrated Discovery (DAVID) and Functional Enrichment Analysis Tool (FunRich) were applied for functional analyses. Results Histopathological evaluation of salivary gland biopsies showed implications of milder inflammation in non-SS subjects through mononuclear cell infiltration, fibrosis and fatty replacement, as compared to pSS patients. Although unaffected in the non-SS group, upregulation of proinflammatory pathways and proteins involved in ubiquitination (LMO7 and HUWE1) and B cell differentiation (TPD52) were detected in tear fluid of pSS patients. Moreover, overexpression of proteins STOM, ANXA4 and ANXA1, regulating cellular innate and adaptive immunological pathways, were further identified in EVs from tear fluid of pSS patients. Finally, whole saliva and EVs isolated from whole saliva of pSS patients expressed proteins vital for innate MHC class I cellular regulation (NGAL) and T cell activation (CD44). Conclusions Non-SS sicca subjects may show implications of mild inflammation in their glandular tissue, while their protein profile was strikingly more similar to healthy controls than to pSS patients. Hence, the tear and salivary biomarkers identified could be implemented as potential non-invasive diagnostic tools that may aid in increasing diagnostic accuracy when evaluating non-SS subjects and pSS patients and monitoring disease progression.

Sjögren’s syndrome (SS) is a complex autoimmune disease associated with lymphocytic infiltration and secretory dysfunction of salivary and lacrimal glands. Although the etiology of SS remains unclear, evidence suggests that epithelial damage of the glands elicits immune and fibrotic responses in SS. To define molecular changes underlying epithelial tissue damage in SS, we laser capture microdissected (LCM) labial salivary gland epithelia from 8 SS and 8 non-SS controls for analysis by RNA sequencing (RNAseq). Computational interrogation of gene expression signatures revealed that, in addition to a division of SS and non-SS samples, there was a potential intermediate state overlapping clustering of SS and non-SS samples. Differential expression analysis uncovered signaling events likely associated with distinct SS pathogenesis. Notable signals included the enrichment of IFN-γ and JAK/STAT-regulated genes, and the induction of genes encoding secreted factors, such as LTF, BMP3, and MMP7, implicated in immune responses, matrix remodeling and tissue destruction. Identification of gene expression signatures of salivary epithelia associated with mixed clinical and histopathological characteristics suggests that SS pathology may be defined by distinct molecular subtypes. We conclude that gene expression changes arising in the damaged salivary epithelia may offer novel insights into the signals contributing to SS development and progression.

There is a critical need to deconvolute the heterogeneity displayed by the minor salivary glands of primary Sjögren’s syndrome (pSS) patients. This is challenging primarily because the disease etiology remains unknown. The hypothesis includes that initial events in the disease pathogenesis target the salivary glands, thereby triggering the development of focal infiltrates (≥50 mononuclear cells) and finally germinal center-like structures. However, the proportion of key mononuclear immune cells residing at these sites, in combination with the overall ratio of morphometric tissue atrophy and adipose infiltration within the minor salivary glands (MSG) parenchyma at distinct phases of inflammatory disease establishment and progression have not been quantified in detail. In this cross-sectional study, we intended to address this problem by stratifying 85 patients into mild (S1), moderate (S2), and severe (S3) stages using the Inflammatory severity index. We found that mild (<3%) and marked (≥3%) levels of atrophy were accompanied by the respective levels of adipose infiltration in the non-SS sicca controls ( p < 0.01), but not in pSS patients. The percentage of adipose infiltration significantly correlated with the age of patients ( r = 0.458, p < 0.0001) and controls ( r = 0.515, p < 0.0001). The CD4 + T helper cell incidence was reduced in the focal infiltrates of the MSG of S2 patients compared to S1 ( p < 0.01), and in S2 compared to S1 and S3 combined ( p < 0.05). CD20 + B cells increased from S1 to S3 ( p < 0.01) and S2 to S3 ( p < 0.01), meanwhile CD138 + plasma cells diminished in S3 patients compared to both S1 and S2 groups combined ( p < 0.01). The proportion of patients with anti-Ro/SSA + , anti-La/SSB + , and RF + increased over the course of inflammatory disease progression and they were significantly more common in the S3 group relative to S1 ( p < 0.05). On the other hand, S2 patients measured a higher mean salivary flow relative to S1 and S3 patients combined ( p < 0.05). Our results demonstrate how the proposed Inflammatory severity index stratification revealed pathological cell and tissue-associated aberrations in the salivary component over the course of inflammatory progression, and their correlations to clinical outcomes. This could be directly transferred to the optimization of available diagnostic strategies applied for pSS patients.

Between the years 2008 and 2023, 306 patients were referred to the Department of Oral Surgery and Oral Medicine, Faculty of Dentistry, University of Oslo, for salivary gland biopsy after clinical suspicion of Sjögren’s syndrome. This study aimed to investigate possible associations between serology and minor salivary gland histopathology by stratifying patients according to serology features (negative, single, or double seropositivity according to anti-SSA and anti-SSB), focus score (FS, negative, or actual score), and germinal centers (GCs). Information was collected from referrals and visits. Collected information included oral and ocular dryness symptoms, sialometry, Schirmer I test, histopathological analysis, and serological findings. Patients were classified using the 2002 American European Consensus Group classification criteria and were stratified into seven subgroups according to their serological profiles and FS, which were compared. The majority of patients were females, and the most frequently referred age group was 50–59 years of age. Most patients had both oral and ocular symptoms. Seropositive patients had higher median FS compared to seronegative patients. Double-seropositive patients had significantly higher median FS compared to single-seropositive patients. The results indicated that anti-SSB together with anti-SSA plays a role in disease severity in the salivary glands. In addition to anti-SSA, anti-SSB should be routinely evaluated as a possible predictor of the severity of inflammatory destruction in the salivary gland tissue.

B cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL) are members of the tumour necrosis factor superfamily. We have examined circulating BAFF and APRIL in relation to serological deviations and lymphoid organization in the salivary glands of the chronic, autoimmune disorder Sjögren's syndrome. Lymphoid organization in the shape of ectopic germinal centers were detected in 33 of 130 consecutive minor salivary gland biopsies and coincided with increased focus score and elevated levels of serum IgG. Follicular dendritic cell networks, proliferation of mononuclear cells and altered B/T cell ratio also separated the two subgroups. Serum levels of sBAFF and sAPRIL were increased in Sjögren's syndrome compared to healthy blood donors, especially in anti-Ro/La+ patients. Though the differences could not be related to germinal center formation, positive correlations between serum levels of sBAFF and sAPRIL, focus score and IgG denotes their possible role in the disease progression of primary Sjögren's syndrome.

The aim of this study was to perform a controlled in situ analysis on the incidence of apoptosis, investigate the expression of apoptosis-mediating proteins, and determine the frequency of apoptotic CD4+ and CD8+ T cells in Sjögren's syndrome (SS). The study was extended to patients with atrophy-fibrosis (AF) not related to SS, as well as to a control group. Immunohistochemistry and the terminal deoxynucleotidyl transferase mediated dUTP digoxigenin nick end labeling (TUNEL) method were applied to study the Fas and FasL expression and the incidence of apoptosis in salivary glands (SG) from patients with primary and secondary SS, AF, and controls. These methods were also combined to enable simultaneous detection of apoptotic and CD4+ or CD8+ T cells. Despite abundant expression of Fas and FasL in SS SG, apoptotic cells were not exceeding 1% in the foci of infiltrating mononuclear cells (IMC). Double staining showed that the frequency of apoptosis was low among both CD4+ and CD8+ T cells. Only a few TUNEL+ epithelial cells were found in all patient groups. Fas was expressed predominantly on SS IMC, single SS epithelial cells, and a few normal acinar cells, but not in AF SG. Although FasL was present on SS and AF IMC and epithelial cells, it was rarely detected in normal tissue. Consequently we demonstrate that Fas-induced apoptosis among SS SG is a rare event. Our findings support an earlier hypothesis indicating that IMC seem to be able to escape apoptosis, resulting in foci of inflammatory cells. Notably, however, no obvious correlation can be drawn to previous studies where a high incidence of apoptosis of epithelial cells was proposed as an important mechanism leading to decreased glandular function, which is a hallmark of SS.

Correspondence to Professor Marie Wahren-Herlenius, Unit of Rheumatology, Department of Medicine, Karolinska Institute, Stockholm 171 76, Sweden; marie.wahren@ki.se Sjögren’s syndrome (SS) is characterised by B cell abnormalities and immune-mediated destruction of exocrine glands, primarily the salivary and lacrimal glands.1 2 Among the reported genetic polymorphisms associated with primary SS (pSS), the FAM167A-BLK locus distinguishes itself as an interesting candidate for further analysis based on the strong expression quantitative locus effect of pSS-associated polymorphisms on FAM167A (member A of the Family with sequence similarity 167), contrasted with only moderate or no effect on BLK.3 4 Little is known about the FAM167A gene and its relevance to rheumatic disease pathogenesis. HeLa (cervical cancer), A375 (malignant melanoma), HEK293 (human embryonic kidney), Jurkat (acute T cell leukaemia), Nalm6 (B cell precursor leukaemia), Raji (B lymphoblast, Burkitt lymphoma), Daudi (B lymphoblast, Burkitt lymphoma), KM3 (plasma cell myeloma), LP-1 (plasma cell myeloma) assessed by real-time PCR. DIORA-1 expression in other B cell populations was confirmed by CD20 staining (online supplementary figure 3).SP110.1136/annrheumdis-2018-213634.supp1 Supplementary data SP210.1136/annrheumdis-2018-213634.supp2 Supplementary data SP310.1136/annrheumdis-2018-213634.supp3 Supplementary data SP410.1136/annrheumdis-2018-213634.supp4 Supplementary data Analysing expression of DIORA-1 in relation to clinical manifestations of pSS, we found that the percentage of DIORA-1+ cells positively correlated with salivary gland focus score as well as serum IgG levels and the presence of Ro/SSA autoantibodies (p<0.001) (figure 1H–J).

Oral symptoms are among the most distressing manifestations for patients with Sjögren’s syndrome (SS). The feeling of dry mouth is unpleasant, and hyposalivation may contribute to difficulty in speaking, chewing and swallowing and reduced quality of life. Reduced salivary flow increases the risk for dental caries and problems with prosthetic replacement. It seems that SS is not as frequently occurring as previously anticipated. Population-based prevalence studies on primary SS in Europe, conducted on large background populations and in accordance with the AECG criteria, reported of a prevalence of 1–9 cases per 10,000 people. This gives a combined prevalence of nearly 39/100,000 (~0.04 %). The cause of Sjögren’s syndrome is even now not fully understood, and the treatment of oral symptoms is still mostly palliative. Hopefully, useful information will appear from the new methods that are now available for genome wide association studies, epigenetics, DNA methylation studies, and proteomics. Similarly, this is anticipated for the immunological side of the story. The interferon signature, the interferon γ/interferon α mRNA ratio, and CXCL13 are among the proposed biomarkers of active disease. In this review, we provide an update on oral aspects of Sjögren’s syndrome with emphasis on the latest publications on these topics.

Sjogren’s syndrome (SS) is a complex autoimmune disease that primarily affects salivary and lacrimal glands and is associated with high morbidity. Although the prevailing dogma is that immune system pathology drives SS, increasing evidence points to structural defects, including defective E-cadherin adhesion, to be involved in its etiology. We have shown that E-cadherin has pivotal roles in the development of the mouse salivary submandibular gland (SMG) by organizing apical-basal polarity in acinar and ductal progenitors and by signaling survival for differentiating duct cells. Recently, E-cadherin junctions have been shown to interact with effectors of the Hippo signaling pathway, a core pathway regulating the organ size, cell proliferation, and differentiation. We now show that Hippo signaling is required for SMG-branching morphogenesis and is involved in the pathophysiology of SS. During SMG development, a Hippo pathway effector, TAZ, becomes increasingly phosphorylated and associated with E-cadherin and α -catenin, consistent with the activation of Hippo signaling. Inhibition of Lats2, an upstream kinase that promotes TAZ phosphorylation, results in dysmorphogenesis of the SMG and impaired duct formation. SMGs from non-obese diabetic mice, a mouse model for SS, phenocopy the Lats2-inhibited SMGs and exhibit a reduction in E-cadherin junctional components, including TAZ. Importantly, labial specimens from human SS patients display mislocalization of TAZ from junctional regions to the nucleus, coincident with accumulation of extracellular matrix components, fibronectin and connective tissue growth factor, known downstream targets of TAZ. Our studies show that Hippo signaling has a crucial role in SMG-branching morphogenesis and provide evidence that defects in this pathway are associated with SS in humans.