Project description:ObjectiveSjögren's syndrome (SS) is a complex multisystem autoimmune disease that results in progressive destruction of the exocrine glands. The purpose of this study was to characterize epigenetic changes in affected gland tissue and describe the relationship of these changes to known inflammatory processes.MethodsA genome-wide DNA methylation study was performed on human labial salivary gland (LSG) biopsy samples obtained from 28 female members of the Sjögren's International Collaborative Clinical Alliance (SICCA) Registry. Gland tissue was methylotyped using the Illumina HumanMethylation450 BeadChip platform, followed by rigorous probe-filtering and data-normalization procedures.ResultsA genome-wide case-control study of 26 of the 28 subjects revealed 7,820 differentially methylated positions (DMPs) associated with disease status, including 5,699 hypomethylated and 2,121 hypermethylated DMPs. Further analysis identified 57 genes that were enriched for DMPs in their respective promoters; many are involved in immune response, including 2 previously established SS genetic risk loci. Bioinformatics analysis highlighted an extended region of hypomethylation surrounding PSMB8 and TAP1, consistent with an increased frequency of antigen-presenting cells in LSG tissue from the SS cases. Transcription factor motif enrichment analysis revealed the specific nature of the genome-wide methylation differences, demonstrating colocalization of SS-associated DMPs with stress- and immune response-related motifs.ConclusionOur findings underscore the utility of CpG methylotyping as an independent probe of active disease processes in SS, offering unique insights into the composition of disease-relevant tissue. Methylation profiling implicated several genes and pathways previously thought to be involved in disease-related processes, as well as a number of new candidates.
Project description:BackgroundActivated T and B cells participate in the development and progression of Sjögren's syndrome (SS). Metformin, a first-line anti-diabetic drug, exerts anti-inflammatory and immunomodulatory effects by activating AMPK. We investigated the therapeutic effect of metformin in non-obese diabetic (NOD)/ShiLtJ mice, an animal model of SS.MethodsMetformin or vehicle was administered orally to the mice for 9 weeks. The salivary flow rate was measured at 11, 13, 15, 17, and 20 weeks. Histological analysis of the salivary glands from vehicle- and metformin-treated mice was conducted. CD4+ T and B cell differentiation in the peripheral blood and/or spleen was determined by flow cytometry. Serum total IgG, IgG1, and IgG2a levels were determined by enzyme-linked immunosorbent assay.ResultsMetformin reduced salivary gland inflammation and restored the salivary flow rate. Moreover, metformin reduced the interleukin (IL)-6, tumor necrosis factor-α, IL-17 mRNA, and protein levels in the salivary glands. Metformin reduced the Th17 and Th1 cell populations and increased the regulatory T cell population in the peripheral blood and spleen and modulated the balance between Tfh and follicular regulatory T cells. In addition, metformin reduced B cell differentiation into germinal center B cells, decreased the serum immunoglobulin G level, and maintained the balance between IL-10- and IL-17-producing B cells.ConclusionMetformin suppresses effector T cells, induces regulatory T cells, and regulates B cell differentiation in an animal model of SS. In addition, metformin ameliorates salivary gland inflammation and hypofunction, suggesting that it has potential for the treatment of SS.
Project description:Objective: Salivary gland ultrasound (SGUS) is emerging as a valid tool in the management of primary Sjögren's syndrome (pSS). This study aimed to investigate whether pSS patients with normal-appearing or pathological SGUS findings showed different clinical, laboratory, and pathologic pSS-related features, and to compare the results by using two different SGUS scores. Methods: Consecutive pSS patients, according to the ACR-EULAR classification criteria, were evaluated. Salivary glands were scored using the early 1992 score by De Vita et al. and the latest 2019 OMERACT score, both being semiquantitative 0-3 scoring systems focused on ultrasonographic parenchymal inhomogeneity (grades 0 and 1, normal-appearing; grades 2 and 3, pathological). The patients were then divided into two groups: "SGUS normal-appearing" if all the salivary glands had normal-appearing parenchyma (grade 0 or 1), or "SGUS pathological" if the grade was 2 or 3 in at least one salivary gland. The associations between SGUS and pSS-related clinical, laboratory, and pathological features were then investigated in the two groups. Results: One hundred pSS patients were evaluated, the mean age (±SD) was 60.9 ± 12.0 years, and mean disease duration was 11.7 ± 7.2 years. Twenty-nine out of 100 (29%) patients were in the "SGUS normal-appearing" group and 71/100 (71%) were in the "SGUS pathological" group. A normal-appearing SGUS was significantly associated with the absence of anti-La/SSB antibodies (p < 0.001) and normal unstimulated salivary flow rate (p = 0.02) by both univariate and multivariate analyses. By univariate analysis, a normal-appearing SGUS was significantly associated also with the absence of rheumatoid factor (p = 0.002) and of serum monoclonal component (p = 0.003), ESSDAI < 5 (p = 0.03), and with a negative lip biopsy (p = 0.029). No associations were found with other items, including anti-Ro/SSA (p = 0.145), Schirmer's test (p = 0.793), ESSPRI (p = 0.47), and demographic data. No differences in these results were observed by using the two SGUS scoring systems. Conclusion: The SGUS allowed the identification of different phenotypes of pSS, and different SGUS scores focused on salivary gland inhomogeneity may be effective to this end.
Project description:ObjectiveMicroRNA reflect physiologic and pathologic processes and may be used as biomarkers of concurrent pathophysiologic events in complex settings such as autoimmune diseases. We generated microRNA microarray profiles from the minor salivary glands of control subjects without Sjögren's syndrome (SS) and patients with SS who had low-grade or high-grade inflammation and impaired or normal saliva production, to identify microRNA patterns specific to salivary gland inflammation or dysfunction.MethodsMicroRNA expression profiles were generated by Agilent microRNA arrays. We developed a novel method for data normalization by identifying housekeeping microRNA. MicroRNA profiles were compared by unsupervised mathematical methods to test how well they distinguish between control subjects and various subsets of patients with SS. Several bioinformatics methods were used to predict the messenger RNA targets of the differentially expressed microRNA.ResultsMicroRNA expression patterns accurately distinguished salivary glands from control subjects and patients with SS who had low-degree or high-degree inflammation. Using real-time quantitative polymerase chain reaction, we validated 2 microRNA as markers of inflammation in an independent cohort. Comparing microRNA from patients with preserved or low salivary flow identified a set of differentially expressed microRNA, most of which were up-regulated in the group with decreased salivary gland function, suggesting that the targets of microRNA may have a protective effect on epithelial cells. The predicted biologic targets of microRNA associated with inflammation or salivary gland dysfunction identified both overlapping and distinct biologic pathways and processes.ConclusionDistinct microRNA expression patterns are associated with salivary gland inflammation and dysfunction in patients with SS, and microRNA represent a novel group of potential biomarkers.
Project description:Sjögren's syndrome (SS) is an autoimmune disease characterized by inflammation with lymphoid infiltration and destruction of the salivary glands. Although many genome-wide association studies have revealed disease-associated risk alleles, the functions of the majority of these alleles are unclear. Here, we show previously unrecognized roles of GTF2I molecules by using two SS-associated single nucleotide polymorphisms (SNPs), rs73366469 and rs117026326 (GTF2I SNPs). We found that the risk alleles of GTF2I SNPs increased GTF2I expression and enhanced nuclear factor-kappa B (NF-κB) activation in human salivary gland cells via the NF-κB p65 subunit. Indeed, the knockdown of GTF2I suppressed inflammatory responses in mouse endothelial cells and in vivo. Conversely, the over-expression of GTF2I enhanced NF-κB reporter activity depending on its p65-binding N-terminal leucine zipper domain. GTF2I is highly expressed in the human salivary gland cells of SS patients expressing the risk alleles. Consistently, the risk alleles of GTF2I SNPs were strongly associated with activation of the IL-6 amplifier, which is hyperactivation machinery of the NF-κB pathway, and lymphoid infiltration in the salivary glands of SS patients. These results demonstrated that GTF2I expression in salivary glands is increased in the presence of the risk alleles of GTF2I SNPs, resulting in activation of the NF-κB pathway in salivary gland cells. They also suggest that GTF2I could be a new therapeutic target for SS.
Project description:ObjectiveA 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.MethodsSGSCs 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.ResultsSGSCs 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.ConclusionThis 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.
Project description:ObjectiveTo evaluate the safety and utility of core needle biopsy (CNB) for diagnosis of salivary gland lymphoma in Sjögren's syndrome (SS).MethodsWe analyzed data from consecutive SS patients who underwent ultrasound-guided major salivary gland CNB for lymphoma diagnosis and determined whether CNB yielded an actionable diagnosis without need for further intervention.ResultsCNBs were performed in 24 patients to evaluate discrete parotid (n = 6) or submandibular (n = 2) gland masses or diffuse enlargement (n = 16; 15 parotid). One patient had 3 CNBs of the same mass. Of the 26 CNBs, 24 included flow cytometry, using CNB and/or fine needle aspirate material, and 14 targeted sonographically identified focal lesions. No patient reported complications. In the 23 patients with 1 CNB, final diagnoses were marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT; n = 6), atypical lymphoid infiltration (n = 3), benign lymphoepithelial sialadenitis (n = 9), normal gland tissue (n = 4), and lymphoepithelial cyst (n = 1). In the patient with serial CNBs, the initial one without flow cytometry was benign, but the next 2 showed atypical lymphoid infiltration. Monoclonal lymphoid infiltration was detected in 12 patients: 6 with MALT lymphoma, 3 were benign, and 3 with atypical lymphoid infiltration. Of the latter 3, 1 was treated with rituximab and 2 with expectant observation. The diagnosis changed from atypical lymphoid infiltration to MALT lymphoma in 1 patient following biopsy of inguinal adenopathy 6 months post-CNB. CNB provided actionable results and avoided open excisional biopsies in all cases.ConclusionCNB is safe and useful in the evaluation of suspected salivary gland lymphoma in SS.
Project description:Salivary gland epithelial cells (SGECs) have been implicated in the pathogenesis of Sjögren's syndrome due to aberrant antigen-presentation function. This study examined the hypothesis that oral dysbiosis modulates the antigen-presentation function of SGECs, which regulates CD4 T cell proliferation in primary Sjögren's syndrome (pSS). Saliva samples from 8 pSS patients and 16 healthy subjects were analyzed for bacterial 16S ribosomal DNA. As a result, 39 differentially abundant taxa were identified. Among them, the phylum Proteobacteria comprised 21 taxa, and this phylum was mostly enriched in the healthy controls. The proteobacterium Haemophilus parainfluenzae was enriched in the healthy controls, with the greatest effect size at the species level. Treatment of A253 cells in vitro with H. parainfluenzae upregulated PD-L1 expression, and H. parainfluenzae-pretreated A253 cells suppressed CD4 T cell proliferation. The suppression was partially reversed by PD-L1 blockade. Among low-grade xerostomia patients, salivary abundance of H. parainfluenzae decreased in pSS patients compared to that in non-pSS sicca patients. Our findings suggest that H. parainfluenzae may be an immunomodulatory commensal bacterium in pSS.
Project description:BackgroundTreatment of patients with Sjögren's syndrome (SjS) is a clinical challenge with high unmet needs. Gene expression profiling and integrative network-based approaches to complex disease can offer an insight on molecular characteristics in the context of clinical setting.MethodsAn integrated dataset was created from salivary gland samples of 30 SjS patients. Pathway-driven enrichment profiles made by gene set enrichment analysis were categorized using hierarchical clustering. Differentially expressed genes (DEGs) were subjected to functional network analysis, where the elements of the core subnetwork were used for key driver analysis.ResultsWe identified 310 upregulated DEGs, including nine known genetic risk factors and two potential biomarkers. The core subnetwork was enriched with the processes associated with B cell hyperactivity. Pathway-based subgrouping revealed two clusters with distinct molecular signatures for the relevant pathways and cell subsets. Cluster 2, with low-grade inflammation, showed a better response to rituximab therapy than cluster 1, with high-grade inflammation. Fourteen key driver genes appeared to be essential signaling mediators downstream of the B cell receptor (BCR) signaling pathway and to have a positive relationship with histopathology scores.ConclusionIntegrative network-based approaches provide deep insights into the modules and pathways causally related to SjS and allow identification of key targets for disease. Intervention adjusted to the molecular traits of the disease would allow the achievement of better outcomes, and the BCR signaling pathway and its leading players are promising therapeutic targets.