Short-term administration of selected anti-T-cell receptor V beta chain specific MoAb reduces sialadenitis in MRL/lpr mice

Animal models of Sjögren's syndrome

Sjögren's syndrome is an autoimmune, chronic inflammatory disease characterized by focal mononuclear cell infiltration of exocrine tissues, accompanied by loss of secretory function. The pathogenesis of autoimmune diseases is complex and, therefore, difficult to study in vitro. As of today, the role of initiating factors remains obscure, clinical symptoms develop late, and there are no tests for early diagnosis of SS. Hence, the disease is difficult to detect and treat. Animal models may provide insights into the identification of target antigens, narrowing the relevant pathological immune mechanisms, and to study the evolution of tissue pathology. This review summarizes current knowledge on murine strains, both spontaneous and induced models, used to study Sjögren's syndrome. Special attention is paid to the characteristics of different strains regarding their properties to mimic specific aspects or stages of the disease.

Sjögren's syndrome in mice carrying the Ipr(cg) gene and the therapeutic efficacy of an immunosuppressive agent FK506

The influence of the Ipr(cg) gene on the development of Sjögren's syndrome was followed up to 5 months of age in male and female mice of MRL, CBA and C3H strains. In MRL-Ipr(cg) mice, focal mononuclear cell infiltration started at 2 months and became conspicuous after 3 months of age in the lacrimal and submandibular glands but was minimal in the parotid and sublingual glands, even at 5 months of age, without any apparent sex effects found. In CBA and C3H mice carrying the Ipr(cg) gene, this manifestation of Sjögren's syndrome was much less prominent, indicating that the participation of some genes of the MRL strain may be indispensable for the development of Sjögren's syndrome in mice carrying this gene. In MRL-Ipr(cg) mice, an immunosuppressive agent, FK506, improved the serological abnormalities (decreased levels of anti-double-stranded DNA antibody of IgG2a and IgG3 subclasses) and proteinuria. It also reduced the manifestations of Sjögren's syndrome when it was intraperitoneally administered three times weekly at a dose of 2 mg/kg from 6 weeks (before disease onset) until 5 months of age (the termination of the experiment). Although VP8.2+ T cells have been demonstrated to be responsible for causing several autoimmune diseases, the selective deletion of Vp8.2+ T cells with the superantigen encoded by mouse mammary tumor virus did not affect the disease severity at all, suggesting that this T cell repertoire may not play a crucial role in induction of Sjögren's syndrome.

Effects of sialadenitis after cellular transfer in autoimmune MRL/lpr mice

The MRL/Mp mice bearing a lymphoproliferative gene, lpr (MRL/Mp-lpr/lpr), provide an appropriate model for the study of autoimmune mechanisms leading to the destruction of salivary and lacrimal gland tissue in Sjögren's syndrome. By 7-8 weeks of age, progressive focal inflammatory cell infiltrates are observed in salivary glands. We examined the possibility of transferring this disorder into syngeneic, young animals. Spleen cells and infiltrating mononuclear cells (MNC) enzymatically eluted from salivary glands were used. The results showed that sialadenitis could be transferred in vivo to young MRL/lpr mice by splenic and salivary gland MNC. The most striking finding was observed in male recipients where the highest incidence of sialadenitis (5/5) was seen in the group injected intravenously with a small dose (1 x 10(6) of salivary gland MNC, CD8+ splenic cells alone were not able to transfer disease. On the other hand, CD4+ splenic cells induced a more severe sialadenitis compared to the control animals. The transfer of pooled cells from salivary glands resulted in the most severe and accelerating sialadenitis (P < 0.05) in female recipients compared with the control animals. Overall, the highest sialadenitis scores (> 0.10) were obtained only after transfer of CD4+ spleen cells and infiltrating salivary gland MNC. These findings indicate that sialadenitis in MRL/lpr mice is mediated by cellular mechanisms and suggest that the infiltrating MNC have the ability to accelerate autoimmune disease in the salivary glands.