The role of stroma and epithelial cells in primary Sjögren's syndrome

Single-cell transcriptome profiling reveals immune and stromal cell heterogeneity in primary Sjögren's syndrome

Primary Sjögren's syndrome (pSS) is a complex autoimmune disease characterized by lymphocytic infiltration and exocrine dysfunction, particularly affecting the salivary gland (SG). We employed single-cell RNA sequencing to investigate cellular heterogeneity in 11 patients with pSS and 5 non-SS controls. Notably, patients with pSS exhibited downregulated SOX9 in myoepithelial cells, potentially associated with impaired epithelial regeneration. An expanded ACKR1+ endothelial subpopulation in patients with pSS suggested a role in facilitating lymphocyte transendothelial migration. Our analysis of immune cells revealed expanded IGHD+ naive B cells in peripheral blood from patients with pSS. Pseudotime trajectory analysis outlined a bifurcated differentiation pathway for peripheral B cells, enriching three subtypes (VPREB3+ B, BANK1+ B, CD83+ B cells) within SGs in patients with pSS. Fibroblasts emerged as pivotal components in a stromal-immune interaction network, potentially driving extracellular matrix disruption, epithelial regeneration impairment, and inflammation. Our study illuminates immune and stromal cell heterogeneity in patients with pSS, offering insights into therapeutic strategies.

The plasma exosomes from patients with primary Sjögren's syndrome contain epithelial cell-derived proteins involved in ferroptosis

Primary Sjögren's syndrome (pSS) is an autoimmune disease represented by exocrine gland epithelial cell lesions. However, the mechanism underlying these lesions remains unclear. This study analyzed the plasma exosomes of pSS patients using proteomics and revealed the presence of 24 differentially expressed proteins (DEPs) involved in the primary biological processes and signaling pathways related to ferroptosis. The DEPs enriched in the ferroptosis-related items were represented by downregulated ceruloplasmin (CP) and transferrin (TF). CC analysis of GO enrichment showed that CP and TF were localized at the apical plasma membrane, which is currently found only in epithelial cells. PPI analysis indicated that these exosomal DEPs formed a clustering network containing CP and TF. Among them, C5, C9, Haptoglobin (HP), and SERPING1 interacted directly with CP and TF. Notably, the expression of these proteins significantly decreased in both the pSS and secondary Sjögren's syndrome (sSS) plasma exosomes but not in non-autoimmune sicca syndrome (nSS). In addition, their expression levels were significantly different in the exosomes and plasma. More importantly, the plasma and salivary exosomes of pSS patients contain higher levels of exocrine gland epithelial autoantigens SSA and SSB than those of healthy controls, and epithelial cells with positive labial glands biopsy (LGB) were more susceptible to ferroptosis than those with negative LGB. The results indicated that ferroptosis may be closely related to SS epithelial cell lesions. KEY MESSAGES: • pSS plasma exosomes contain epithelial cell-derived proteins involved in ferroptosis. • Complement C5 and C9 may be new molecules involved in ferroptosis and play a crucial role in pSS epithelial cell pathology. • The serum exosomes from pSS patients, not nSS patients, contain ferroptosis-related proteins. • The changes in the ferroptosis-related protein content in the exosomes can better reflect the state of the epithelial cell lesions than those in the plasma.

Lessons from Animal Models in Sjögren's Syndrome

Primary Sjögren's syndrome (pSS) is a connective tissue disease characterized by a wide spectrum of clinical features, extending from a benign glandular disease to an aggressive systemic disorder and/or lymphoma. The pathogenesis of Sjögren's syndrome (SS) is not completely understood, but it is assumed that pathogenesis of SS is multifactorial. The studies based on the animal models of SS provided significant insight in SS disease pathogenesis and management. The aim of this review is to summarize current studies on animal models with primary SS-like symptoms and discuss the impact of these studies on better understanding pathogenesis and management of Sjögren's syndrome. Databases PubMed, Web of Science, Scopus and Cochrane library were searched for summarizing studies on animal models in SS. Available data demonstrate that animal models are highly important for our understanding of SS disease.

Lacrimal and salivary gland ultrasound - how and when to use in patients with primary Sjögren's syndrome

This paper addresses how to perform an ultrasound assessment of the salivary and lacrimal glands, how to identify pathological changes, and how to score disease activity, focusing on the use for primary Sjögren's syndrome (pSS). It addresses the role of salivary gland ultrasound for diagnosing and management of patients with pSS and touches upon the use for differential diagnosis, including how and when to perform ultrasound-guided biopsies and injections.

Tertiary Lymphoid Structures: A Potential Biomarker for Anti-Cancer Therapy

A tertiary lymphoid structure (TLS) is a special component in the immune microenvironment that is mainly composed of tumor-infiltrating lymphocytes (TILs), including T cells, B cells, DC cells, and high endothelial venules (HEVs). For cancer patients, evaluation of the immune microenvironment has a predictive effect on tumor biological behavior, treatment methods, and prognosis. As a result, TLSs have begun to attract the attention of researchers as a new potential biomarker. However, the composition and mechanisms of TLSs are still unclear, and clinical detection methods are still being explored. Although some meaningful results have been obtained in clinical trials, there is still a long way to go before such methods can be applied in clinical practice. However, we believe that with the continuous progress of basic research and clinical trials, TLS detection and related treatment can benefit more and more patients. In this review, we generalize the definition and composition of TLSs, summarize clinical trials involving TLSs according to treatment methods, and describe possible methods of inducing TLS formation.

Genome-Wide DNA Methylation Profiling in CD8 T-Cells and Gamma Delta T-Cells of Asian Indian Patients With Takayasu Arteritis

Background: Takayasu’s Arteritis (TA) is a chronic inflammatory disease that affects aorta and its main branches at their origin. Genetic, pathological and functional studies have shown that CD8 and Gamma delta (γ/δ) T-lymphocytes are involved in inflammatory processes in affected regions of arteries causing vascular damage. The molecular function of these lymphocytes remains unclear and currently no epigenetic studies are available in TA. We primarily performed genome wide methylation analysis in CD8 T cells and γδ T cells of patients with TA and compared with healthy controls.

Methods: We recruited 12 subjects in each group namely TA patient and healthy controls. Blood samples were collected after obtaining informed written consent. CD8 T cells and γδ T cells were separated from whole blood. DNA extracted from these cells and were subjected to bisulfite treatment. Finally, bisulfite treated DNA was loaded in Infinium Methylation EPIC array. Bioinformatics analysis was used to identify differential methylation regions which were then mapped to genes.

Results: Interleukin (IL)-32 and Lymphotoxin-A were genes significantly hypomethylated in CD8 T-cells. Anti-inflammatory cytokine genes, IL-10, IL-1RN and IL-27 were hypomethylated in γδ T cells of TA patients as compared to healthy controls. Gene enrichment analysis using Gene Ontology (GO) database and Kyoto Encyclopaedia of Genes and Genomes (KEGG) identified that genes involved in T-cell receptor signalling pathways were hypomethylated in CD8 T-cells and hypermethylated in γδ T cells of TA patients.

Conclusion: CD8 T-cells might play a major role in immunopathogenesis of inflammation in TA, whereas γδ T cells may play a regulatory role.

The IL-33/ST2 Axis Promotes Primary Sjögren's Syndrome by Enhancing Salivary Epithelial Cell Activation and Type 1 Immune Response

The molecular mechanisms of primary Sjögren's syndrome (pSS) are poorly understood. In this study, we explored the role of the IL-33/ST2 axis in the development of pSS. In the mouse model of experimental Sjögren's syndrome, we found that the saliva flow rate at weeks 4 and 30 was preserved in IL-33^-/- and ST2^-/- mice, compared with that of wild-type mice. At week 30 of experimental Sjögren's syndrome induction, the histological score, anti-nuclear Ab levels, and numbers of Th1 and B cells in draining lymph nodes of the salivary gland were lower in the IL-33^-/- and ST2^-/- mice, whereas Th17 cells and regulatory T cells were not changed. Primary salivary gland epithelial cells expressed the IL-33 receptor ST2. After stimulation with rIL-33, salivary gland epithelial cells increased the transcriptional levels of CD86 and CCL2, accompanied by the activation of the NF-κB inflammatory pathway. There was a synergistic effect between rIL-33 and rIL-12 in augmenting the production of IFN-γ in CD4⁺ T cells. In the pSS patients, the expression of IL-33 was elevated in the labial salivary gland, with the number of IL-33⁺ cells positively correlated with the score of the EULAR (European Alliance of Associations for Rheumatology) Sjögren's syndrome disease activity index (ESSDAI). ST2 was highly expressed in the cytoplasm of ductal epithelial cells, with low levels of expression in lymphatic infiltration sites. Our data suggest that the IL-33/ST2 axis may promote the development of pSS by enhancing salivary epithelial cell activation and the type 1 immune response.

Advances in Pathogenesis of Sjögren's Syndrome

Sjögren's syndrome (SS) is a chronic autoimmune disease of unknown etiology that mainly involves exocrine glands. Patients present with dry mouth and eyes, fever, arthralgia, and other systemic symptoms. In severe cases, the quality of life of patients is affected. At present, there is no cure for SS, and the treatment options are extremely limited. In recent years, studies of patients and animal models have identified abnormalities of immune cell function and cytokines to be involved in SS. A systematic review of the literature may clarify the etiology and pathogenesis of SS, as well as provide a theoretical basis for the development of new drugs for the treatment of SS.

Gene expression alterations in salivary gland epithelia of Sjögren's syndrome patients are associated with clinical and histopathological manifestations

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.

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

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

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

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