| Background:Sj?gren’s syndrome(SS)is a chronic autoimmune disease mainly affecting exocrine glands.In addition to xerostomia and xerophthalmia,extra-glandular organs involvement(lungs,kidneys,musculoskeletal and central nervous system)can also be observed.Currently,treatment for SS is limited,with substitution therapy(artificial tears and saliva)and immunoregulation therapy(glucocorticoid and immunosuppressants).Interleukin-33(IL-33)plays an important role in local mucosal immunity as a damage-related molecule.IL-33 can act on innate immunity cells(macrophages,dendritic cells),adaptive immunity cells,and histiocytes.However,the exact mechanism of IL-33 in SS remains unclear.Objective:In this study,the expression pattern of IL-33 and ST2 in the submandibular gland was detected in the mouse model of SS.The effect of the IL-33/ST2 axis was further verified by inducing the model of SS in IL-33 and ST2 knock-out mice.Meanwhile,the expression of IL-33 and its relationship with disease activity were investigated in the pathological sections of labial glands of patients with SS.To clarify the role of the IL-33/ST2 axis in salivary gland injury and provide a new target for the treatment of SS patients.Methods:In vivo,wild-type,IL-33,and ST2 knock-out C57B/6J mice were used for the induction of SS.Serum levels of anti-nuclear antibodies were examined by ELISA.Saliva was collected for 10 minutes following pilocarpine stimulation.Tissue inflammatory cell infiltration was assessed by hematoxylin and eosin staining.Immune cells in the draining cervical lymph nodes of the salivary gland were analyzed by flow cytometry.In vitro,primary mouse salivary gland epithelial cells(SGECs)and bone marrow-derived macrophages(BMDMs)were cultured to detect the levels of chemokines and costimulatory molecules and the activation of inflammatory pathways after IL-33 stimulation.Purified CD4+T cells from mice spleens were treated with anti-CD3 antibodies,anti-CD28 antibodies,recombinant IL-12,or recombinant IL-33 to detect Th1 differentiation in CD4+T cells.For patients,the expression and localization of IL-33 in labial gland tissues of patients with primary Sj?gren’s syndrome(pSS)were detected by immunohistochemistry and immunofluorescence,and the correlation between IL-33 expression and clinical indicators was analyzed.Results:In a mouse model of experimental Sj?gren’s syndrome(ESS),the saliva gland flow rate at week-4 and 30 was increased in IL-33-/-and ST2-/-mice,compared to that of wild-type mice.At week-30 of ESS induction,the histological score,anti-nuclear antibody levels,numbers of Thl and B cells in draining lymph nodes of the salivary gland were lower in the IL-33-/-and ST2-/-mice,while Th17 cells and Treg were not changed.Primary SGECs and BMDMs expressed the IL-33 receptor ST2.After stimulation with rIL-33,SGECs increased the transcriptional levels of CD86,CCL2,and ST2,accompanied by the activation of the NF-κB inflammatory pathway.In addition,rIL-33 stimulation increased the transcriptions of ICAM-1,CCL2,and CCL5 in BMDMs.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-positive cells positively correlated with the score of EULAR Sj?gren’s Syndrome Disease Activity Index(ESSDAI).ST2 was highly expressed in the cytoplasm of ductal epithelial,with low levels of expression in lymphatic infiltration sites.Conclusion:Our data suggest that the IL-33/ST2 axis may promote the development of SS by enhancing salivary epithelial cell injure and type 1 immune response. |
