Establishment Of A Novel Mouse Model For Sj(?)gren’s Syndrome By Immunization With Short Peptides Of Ro60Antigen

Objective:Primary Sjogren’s syndrome （pSS） is an autoimmune disease affecting the exocrine glands and leading to the mucosal and conjunctival dryness. One important feature of the pSS is anti-Ro60/SSA antibodies in the serum of the majority of patients. The pathogenic autoantigen of pSS is not clear, and there is a lack of a good animal model induced by active immunization with autoantigen. Here we aimed to develop a novel mouse model for pSS and to investigate the role of Ro6O in the pathogenesis of pSS.Methods:BALB/c mice were immunized with Ro60₃16-335peptide, Ro60₄80-494peptide or PBS control in presence of Titermax or CFA as the adjuvant. The anti-Ro peptide IgG and its subclasses as well as cytokines were determined in the serum of mice by ELISA. Salivary and tear secretion were measured at day0, day45and day90/120after the immunization. Mice were scarified on day90/120after immunization, and salivary glands, lacrimal glands and other tissues were collected for further histological and immunological evaluations. The inflammatory cell infiltration was detected using an immunofluorescence staining protocol. Meanwhile, autoimmune IgG deposition was determined in the lacrimal glands by direct immunofluorescence technique. The pathogenicity of the IgG from the immunized mice was determined by passive transfer of the IgG to normal BALB/c mice.Results:BALB/c mice immunized with Ro60₃16-335peptides emulsified with Titermax adjuvant developed immunological and clinical phenotypes similar to pSS at day90after the immunization. The mice showed a significant decrease in tear secretion, and the histological and structural changes were observed in lacrimal glands of the mice. Furthermore, anti-Ro60₃16-335IgG was detected in mouse serum, and autoantibody deposition was observed in the lacrimal glands. The levels of proinflammatory cytokines including IFN-y and IL-17A were significantly increased in the Ro60₃16-335immunized mice as compared with controls. Meanwhile, the lacrimal glands were characterized with infiltration in inflammatory cells including B cells, T cells, macrophage and neutrophil. The above mentioned immunological and clinical phenotypes were observed neither in mice immunized with Ro60₄80-494peptide nor in control mice immunized with PBS in presence of Titermax as adjuvant. In contrast, BALB/c mice immunized with Ro60₃16-335peptides emulsified with CFA adjuvant developed IgG against the peptides but did not showed other immunological and clinical phenotypes.Conclusion:We successfully established a novel mouse model of pSS by immunizing BALB/c mice with Ro60₃16-335peptide in presence of Titermax as adjuvant. This novel model of pSS will be a usefull tool for the investigating the pathogenesis of pSS as well as for testing the efficacy of novel therapeutics. Meanwhile, this also suggests that immune response against Ro6O autoantigen play a role in the pathogenesis of pSS, and the role of Ro6O in pSS seems to be T cell epitope dependent and adjuvant dependent.