McH-lpr/lpr-RA1 mice: A novel spontaneous mouse model of autoimmune sialadenitis

Many studies of the autoimmune disease Sjögren's syndrome have been performed using spontaneous mouse models. In the present study, we describe the characteristics of McH/lpr-RA1 mice and propose their use as a novel murine model of autoimmune sialadenitis. The McH/lpr-RA1 mouse is a recombinant congenic strain derived from generation F54 or more of MRL-Fas^lpr x (MRL- Fas^lpr x C3H- Fas^lpr) F1. We show for the first time that this mouse spontaneously develops autoimmune sialadenitis and vasculitis in submandibular gland tissues. Sialadenitis was accompanied by extensive inflammatory cell infiltration and tissue destruction. Immunohistochemical studies revealed that the salivary gland lesions strongly expressed four sialadenitis-related molecules: SSA and SSB (autoantigens of Sjögren's syndrome), gp91phox (an accelerator of reactive oxygen species production) and single strand DNA (a marker of apoptotic cells). In contrast, expression of aquaporin-5 (AQP5), which stimulates salivary secretion was weak or negligible. Statistical correlation analyses indicated that the apoptosis of salivary gland cells provoked by oxidative stress contributed to the severe sialadenitis and reduced expression of AQP5. Our study has demonstrated that McH/lpr-RA1 mice spontaneously develop the pathognomonic features of autoimmune sialadenitis and thus could be used as a new animal model of Sjögren's syndrome.