Blocking IAg(7) class II major histocompatibility complex by drug-like small molecules alleviated Sjogren's syndrome in NOD mice.

BACKGROUND: Sjogren's syndrome (SjS) is an autoimmune disease with a strong genetic association. To date, no vaccine or therapeutic agent exists to cure SjS, and patients must rely on lifelong therapies to treat symptoms. Human leukocyte antigens (HLA) are primary susceptibility loci that form the genetic basis for many autoimmune diseases, including SjS. In this study, we sought to determine whether blocking MHC class II IAg(7) antigen presentation in the NOD mouse would alleviate SjS by preventing the recognition of autoantigens by pathogenic T cells. METHODS: Mapping of the antigenic epitopes of Ro60 autoantigen to IAg(7) of the NOD mice was performed using structural modeling and in-vitro stimulation. Tetraazatricyclo-dodecane (TATD) and 8-Azaguanine (8-Aza) were previously identified as potential binders to IA(g7) of the NOD mice using in silico drug screening. Mice were treated with 20mgs/kg via IP every day five days/week for 23 weeks. Disease profiling was conducted. FINDINGS: Specific peptides of Ro60 autoantigen were identified to bind to IAg(7) and stimulated splenocytes of the NOD mice. Treating NOD mice with TATD or 8-Azaguanine alleviated SjS symptoms by improving salivary and lacrimal gland secretory function, decreasing the levels of autoantibodies, and reducing the severity of lymphocytic infiltration in the salivary and lacrimal glands. INTERPRETATION: This study presents a novel therapeutic approach for SjS by identifying small molecules capable of inhibiting T cell response via antigen-specific presentation. FUNDING: CQN is supported financially in part by PHS grants AI130561, DE026450, and DE028544 from the National Institutes of Health.