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

Melatonin inhibits salivary gland epithelial cell ferroptosis via the NRF2/HO-1/GPX4 signaling pathway in primary Sjögren's syndrome

BACKGROUND

Primary Sjögren's syndrome (pSS) is an autoimmune disease characterized by xerostomia and autoimmune sialadenitis. Interferon-γ (IFN-γ) induces ferroptosis in salivary gland epithelial cells (SGECs), leading to salivary gland (SG) hypofunction. We previously demonstrated the beneficial effects of melatonin (MLT) in alleviating SG dysfunction and inflammation in a pSS animal model. However, the precise underlying mechanism remains unclear.

METHODS

Female NOD/ltj and ICR mice were used as the pSS mouse model and control group, respectively. MLT was administered via intraperitoneal injection to NOD/ltj mice to detect its effect on ferroptosis in SGs. Primary human SGECs and A253 cells were treated with IFN-γand ferroptosis inducers, with or without MLT.

RESULTS

Exogenous MLT alleviated pathological SG alterations and promoted saliva production through inhibiting SGEC ferroptosis. MLT inhibited SGEC ferroptosis induced by IFN-γ and ferroptosis inducers via nuclear factor erythroid 2-related factor 2/heme oxygenase-1/glutathione peroxidase 4 (NRF2/HO-1/GPX4) pathway activation. Moreover, MLT suppressed the nuclear factor-kappa B (NF-κB) pathway, which is triggered by ferroptosis in SGECs. Nevertheless, ML385-mediated NRF2 inhibition abrogated the antiferroptotic protective effects of MLT on SGECs.

CONCLUSIONS

MLT inhibits SGEC ferroptosis through NRF2/HO-1/GPX4 pathway activation and thus attenuates ferroptosis-triggered NF-κB activity. Melatonin represents a potential therapeutic approach for pSS owing to its capacity to regulate ferroptosis.

The Potential Contribution of the IL-37/IL-18/IL-18BP/IL-18R Axis in the Pathogenesis of Sjögren's Syndrome

The objective of this study was to explore the expression profile of the Interleukin (IL)-37/IL-18/IL-18BP/IL-18R axis in patients with primary Sjögren's syndrome (pSS). This study included 36 patients diagnosed with pSS, 13 patients presenting with sicca symptoms without confirmed pSS, and 14 healthy controls. Serum concentrations of IL-37, IL-18, IL-18BP, and IL-18R were measured using a sandwich ELISA. These levels were then correlated with relevant clinical and biological parameters. Furthermore, expression of the same cytokines was assessed in salivary gland biopsies via immunohistochemistry. No significant difference in serum IL-37 levels was observed among the three groups (p = 0.1695). However, serum levels of IL-18 and IL-18BP were significantly elevated in pSS patients compared to healthy controls (p < 0.0001), and these levels were strongly correlated. Immunohistochemical analysis revealed significantly higher expression of IL-37 in both the excretory ducts and inflammatory infiltrates of salivary glands in pSS patients compared to sicca patients. No correlation was found between IL-37 expression and the histological severity of glandular infiltration as assessed by the Chisholm score. In addition, an enhanced expression of IL-18, IL-18BP, and IL-18Rα was observed in the salivary glands of pSS patients. These findings suggest the potential contribution of the IL-37/IL-18/IL-18BP/IL-18R signaling axis in the pathogenesis of Sjögren's syndrome, particularly through its increased expression in salivary glands and correlation with disease-specific inflammatory markers. These findings may contribute to a better understanding of pSS immunopathology and suggest new avenues for biomarker development or therapeutic targeting.

Mechanism of Luteolin in the Treatment of Primary Sjogren's Syndrome: a Study Based on Systems Biology and Cell Experiments

INTRODUCTION

Primary Sjogren's Syndrome (pSS) is a chronic inflammatory autoimmune disease that manifests as dry mouth and eyes. Luteolin can repress immuno-inflammation and improve the function of exocrine glands.

METHODS

Bibliometrics was used to visualize pSS-related key indicators. The efficacy of traditional Chinese medicines (TCMs) in pSS treatment was analyzed with the internal database containing the clinical records of pSS. Using the network pharmacology technology to identify involved pathways. Additionally, molecular docking and cell experiments were performed to screen and verify the therapeutic effect of luteolin on pSS.

RESULTS

Key indicators that were selected according to the bibliometrics were worse in pSS and had certain compatibility and correlation with laboratory and immunoinflammatory indicators. After treatment, pSS patients showed improvements in the above indicators. The results of risk analyses revealed that TCMs were protective factors for laboratory indicators and key indicators. The main effective TCMs for pSS treatment and TNF pathways were identified with network pharmacology. Cell experiments validated that luteolin indeed improved the secretion dysfunction and inflammation of modeled human submandibular gland epithelial cells through the TNF/NF-κB pathway.

CONCLUSIONS

TCMs may effectively improve transcription factors and immuno-inflammatory markers in pSS patients. Moreover, we hypothesized and verified the potential mechanism of action of luteolin in HSG cells.

Explore the possible influence of Sjogren's syndrome on thyroid cancer: A literature data mining and meta-analysis

OBJECTIVES

To explore the potential influence of Sjogren's syndrome (SS) on thyroid cancer (TC).

METHODS

First, a literature data mining (LDM) approach was used to reconstruct functional pathways connecting SS and TC. A meta-analysis was then performed to examine the expression changes of genes mediated by SS using 16 TC case/control expression datasets, with results validated through the TCGA/GTEx dataset. Finally, gene set enrichment analysis (GSEA) and survival analysis using GEPIA2 were conducted on the significant genes.

RESULTS

Our findings indicate that SS may increase the risk of TC by activating 14 TC promoters (PDCD1, NTRK1, LGALS3, CD274, FOXP3, BCL2, CYP1A1, HMGB1, TGFB1, CCL2, PLA2G7, TFF3, LCN2, and CLDN1) and suppressing three TC inhibitors (MIR145, MIR30C1, and EP300). Four molecules (PLA2G7, TFF3, LCN2, and CLDN1) exhibited significant expression changes in TC patients (LFC > 1 or < -1; p < 2.07E-04), which were confirmed in TCGA/GTEx expression analysis. These results highlight three possible mechanisms-the SS-PLA2G7-CCL2-TC pathway, the SS-LCN2-LGALS3-TC pathway, and the SS-CLDN1-BCL2-TC pathway-that may explain how SS contributes to TC development. Enrichment analysis suggests that SS may affect TC prognosis by regulating leukocytes and tolerance induction. Survival analysis indicates that SS may enhance TC survival through the regulation of the CLDN1 and EGF pathways.

CONCLUSION

LDM-based pathway analysis highlighted three genetic pathways through which SS may adversely affect TC progression, while SS may enhance TC survival via the CLDN1 and EGF pathways, highlighting the need for further research.

The role of cytokines from salivary gland epithelial cells in the immunopathology of Sjögren's syndrome

In the pathogenesis and progression of Sjögren's syndrome (SS), hematopoietic cells in the peripheral circulation, tissue-resident immune cells, and parenchymal cells of salivary gland tissues (such as epithelial cells, endothelial cells, fibroblasts, etc.) all play crucial roles. These diverse cells form intricate networks and interact with each other, leading to tissue destruction and persistent chronic inflammation, ultimately causing irreversible damage in glandular function. Among these, salivary gland epithelial cells (SGECs) consistently hold a key position, characterized by their functions in expressing co-stimulatory and antigen-presenting molecules and secreting pro-inflammatory cytokines and chemokines. Moreover, SGECs actively engage in and facilitate the development of specific pathological structures within the salivary gland, such as lymphoepithelial lesions (LELs) and tertiary lymphoid structures (TLSs), thereby substantially elevating the risk of mucosa-associated lymphoid tissue (MALT) lymphoma. Overall, SGECs are recognized for their essential and irreplaceable contributions to the pathogenesis of SS. This review article initially delves into the anatomical composition of salivary gland epithelial cells, subsequently focusing on elucidating the different cytokines derived from SGECs, encompassing chemokines, pro-inflammatory cytokines, anti-inflammatory cytokines, pro-survival cytokines, and damage-associated molecular patterns (DAMPs), to explore their key roles in the pathogenesis of SS.

The intriguing role of IL33/ST2 axis signaling in oral diseases - A systematic review

PURPOSE

Oral diseases act as a silent epidemic, and the pathogenetic role of interleukin-33/suppression of tumorigenicity-2 axis (IL-33/ST2) remains unclear due to a lack of literature. This review has attempted to highlight the importance of this axis in oral diseases, which may be helpful in developing therapeutic modalities required to halt disease progression.

MATERIALS AND METHODS

A thorough search was conducted using various databases. Original research articles that assessed both IL-33 and ST2 levels in oral diseases using different techniques were included in the review. The risk of bias for each study was analyzed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool and Review Manager 5.4 was used to output the results.

RESULTS

In the qualitative data synthesis we included 13 published articles. The most commonly used method was serum estimation, while methods with optimistic results were saliva, real-time quantitative polymerase chain reaction and immunohistochemistry. The predominant mechanism of action was nuclear factor kappa B signaling and type 2 immune response. However, salivary gland epithelial cell activation, activation of mast cells, type 1 immune response, and upregulated angiogenesis are crucial in mediating IL-33/ST2 signaling in oral diseases.

CONCLUSIONS

Accumulating evidence demonstrates that the IL-33/ST2 axis is a fundamental pathogenetic mechanism of oral diseases of inflammatory, autoimmune, or neoplastic origin.

Biological effects of IL-33/ST2 axis on oral diseases: autoimmune diseases and periodontal diseases

IL-33 is a relatively new member of the IL-1 cytokine family, which plays a unique role in autoimmune diseases, particularly some oral diseases dominated by immune factors. The IL-33/ST2 axis is the main pathway by which IL-33 signals affect downstream cells to produce an inflammatory response or tissue repair. As a newly discovered pro-inflammatory cytokine, IL-33 can participate in the pathogenesis of autoimmune oral diseases such as Sjogren's syndrome and Behcet's disease. Moreover, the IL-33/ST2 axis also recruits and activates mast cells in periodontitis, producing inflammatory chemokines and mediating gingival inflammation and alveolar bone destruction. Interestingly, the high expression of IL-33 in the alveolar bone, which exhibits anti-osteoclast effects under appropriate mechanical loading, also confirms its dual role of destruction and repair in an immune-mediated periodontal environment. This study reviewed the biological effects of IL-33 in autoimmune oral diseases, periodontitis and periodontal bone metabolism, and elaborated its potential role and impact as a disease enhancer or a repair factor.

Pathogenesis and treatment of Sjogren's syndrome: Review and update

Sjogren's syndrome (SS) is a chronic autoimmune disease accompanied by multiple lesions. The main manifestations include dryness of the mouth and eyes, along with systemic complications (e.g., pulmonary disease, kidney injury, and lymphoma). In this review, we highlight that IFNs, Th17 cell-related cytokines (IL-17 and IL-23), and B cell-related cytokines (TNF and BAFF) are crucial for the pathogenesis of SS. We also summarize the advances in experimental treatment strategies, including targeting Treg/Th17, mesenchymal stem cell treatment, targeting BAFF, inhibiting JAK pathway, et al. Similar to that of SLE, RA, and MS, biotherapeutic strategies of SS consist of neutralizing antibodies and inflammation-related receptor blockers targeting proinflammatory signaling pathways. However, clinical research on SS therapy is comparatively rare. Moreover, the differences in the curative effects of immunotherapies among SS and other autoimmune diseases are not fully understood. We emphasize that targeted drugs, low-side-effect drugs, and combination therapies should be the focus of future research.

The Interleukin-33/ST2 Axis Enhances Lung-Resident CD14+ Monocyte Function in Patients with Non-Small Cell Lung Cancer

Interleukin-33 (IL-33) binds to its cognate receptor suppression of tumorigenicity 2 (ST2), leading to critical modulatory roles in immune responses during inflammation and cancers. The aim of this study was to investigate the role of IL-33/ST2 signaling in monocyte function in non-small cell lung cancer (NSCLC). Sixty-two NSCLC patients and nineteen controls were enrolled. IL-33 levels and ST2 expression were measured in peripheral blood and bronchoalveolar lavage fluid (BALF) by ELISA and flow cytometry. HLA-DR expression by CD14+ monocytes, granzyme B and proinflammatory cytokine secretion were also investigated in lipopolysaccharide-stimulated cells. CD14+ monocytes purified from BALF in the tumor site were stimulated with IL-33 in vitro, and co-cultured with a lung cancer cell line A549 cells. The cytotoxicity of monocytes with IL-33 stimulation was then assessed. IL-33 levels were lower in the peripheral blood and tumor microenvironment of NSCLC patients. There was no significant difference in peripheral ST2 expression between NSCLC patients and controls. Soluble ST2 levels were increased but membrane-bound ST2 expression in CD14+ monocytes was decreased in tumor microenvironment of NSCLC patients. There were no remarkable differences in either HLA-DR expression or proinflammatory cytokine secretion by circulating CD14+ monocytes between NSCLC patients and controls. CD14+ monocytes in the tumor microenvironment revealed a dysfunctional phenotype, which presented as lower HLA-DR expression and reduced granzyme B and proinflammatory cytokines. A higher concentration of IL-33 stimulation promoted tumor-resident CD14+ monocyte-induced target cell death. The present study indicates that IL-33/ST2 signaling pathway might enhance the activity of tumor-resident CD14+ monocytes in NSCLC.

Bioinformatics analysis identified immune infiltration, risk and drug prediction models of copper-induced death genes involved in salivary glands damage of primary Sjögren's syndrome

This study aimed to identify copper-induced death genes in primary Sjögren's syndrome (pSS) and explore immune infiltration, risk and drug prediction models for salivary glands (SGs) damage. The 3 datasets, including GSE40611, GSE23117, and GSE7451 from the Gene Expression Omnibus database were downloaded. The datasets were processed using the affy in R (version 4.0.3). In immune cells, copper-induced death genes were strongly expressed in "activated" dendritic cells (aDCs), macrophages and regulatory T cells (Treg). In immune functions, copper-induced death genes were strongly expressed in major histocompatibility complex (MHC) class I, human leukocyte antigen (HLA) and type I interferon (IFN) response. Correlation analysis showed that 5 genes including SLC31A1, PDHA1, DLD, ATP7B, and ATP7A were significantly correlated with immune infiltration. The nomogram suggested that the low expression of PDHA1 was significant for predicting the risk of pSS and the area under curve was 0.678. Drug model suggested that "Bathocuproine disulfonate CTD 00001350," "Vitinoin CTD 00007069," and "Resveratrol CTD 00002483" were the drugs most strongly associated with copper-induced death genes. In summary, copper-induced death genes are associated with SGs injury in pSS, which is worthy of clinicians' attention.

Dual Immune Regulatory Roles of Interleukin-33 in Pathological Conditions

Interleukin-33 (IL-33), a member of the IL-1 cytokine family and a multifunctional cytokine, plays critical roles in maintaining host homeostasis and in pathological conditions, such as allergy, infectious diseases, and cancer, by acting on multiple types of immune cells and promoting type 1 and 2 immune responses. IL-33 is rapidly released by immune and non-immune cells upon stimulation by stress, acting as an “alarmin” by binding to its receptor, suppression of tumorigenicity 2 (ST2), to trigger downstream signaling pathways and activate inflammatory and immune responses. It has been recognized that IL-33 displays dual-functioning immune regulatory effects in many diseases and has both pro- and anti-tumorigenic effects, likely depending on its primary target cells, IL-33/sST2 expression levels, cellular context, and the cytokine microenvironment. Herein, we summarize our current understanding of the biological functions of IL-33 and its roles in the pathogenesis of various conditions, including inflammatory and autoimmune diseases, infections, cancers, and cases of organ transplantation. We emphasize the nature of context-dependent dual immune regulatory functions of IL-33 in many cells and diseases and review systemic studies to understand the distinct roles of IL-33 in different cells, which is essential to the development of more effective diagnoses and therapeutic approaches for IL-33-related diseases.