Expression profile between mast cells from diabetic prone and diabetic resistant rat strains

Abstract Human type 1 diabetes mellitus (T1DM) arises through autoimmune destruction of pancreatic ? cells and is modeled in many respects by the lymphopenic and spontaneously diabetic BioBreeding (BB) DRlyp/lyp rat. Previously, pre-onset expression profiling of whole DRlyp/lyp pancreatic lymph nodes (PLN) revealed innate immune activity, specifically that of mast cells and eosinophils. Furthermore, we observed that pancreatic islets of DRlyp/lyp rats as well as those of diabetes-inducible BB DR+/+ rats potentially recruit innate cells through eotaxin expression. Here we determine that lifelong eotaxin expression begins before 40 days of life and localized specifically to ? cells. In this report, we find PLN mast cells more abundant in DRlyp/lyp compared to related BB DR+/+ rats (2.1 +/-0.9% versus 0.9+/-0.4% of total cells, p<0.0001). DRlyp/lyp PLN mast cell gene expression profiling revealed an activated population and included significant overrepresentation of transcripts for mast cell protease 1, cationic trypsinogen, carboxypeptidase A, IL-5, and phospholipase C?. In the DR+/+ rat, which develops T1DM upon depletion of TREG cells, mast cells displayed gene expression consistent with the negative regulation of degranulation, including significant overrepresentation of transcripts encoding tyrosine phosphatase SHP-1, lipid phosphatase SHIP, and E3 ubiquitin ligase c-Cbl. To recapitulate negative mast cell regulation observed in the DR+/+, we treated DRlyp/lyp rats with the mast cell “stabilizer” cromolyn which significantly (p<0.05) delayed T1DM onset. These findings are consistent with a growing body of evidence in humans and animal models where a role for mast cells in the initiation and progression of autoimmune disease is emerging. Keywords: Expression profile between disease and control