Effects of Muscarinic Acetylcholine 3 Receptor(208-227) Peptide Immunization on Autoimmune Response in Nonobese Diabetic Mice

The second extracellular loop (LFWQYFVGKRTVPPGECFIQFLSEPTITFGTAI, aa 205–237) of muscarinic acetylcholine 3 receptor (M3R) has been reported to be an epitope for autoantibodies generated during certain autoimmune disorders, including Sjögren's syndrome (SS). Autoantibodies against M3R(228–237) have been shown to interfere with the function of M3R. However, few studies have been performed on the M3R(205–227) peptide of the second extracellular loop. In the current study, we sought to investigate the effect of M3R(208–227) peptide immunization on autoimmune response in NOD/LtJ mice. We synthesized the M3R(208–227) peptide and immunized NOD/LtJ mice to investigate whether peptide-specific antibodies could be generated and whether immunization would lead to changes in autoimmune response in NOD/LtJ mice. Our results demonstrate that the secretions of Th-1, Th-2, and Th-17 cytokines are downregulated and lymphocytic infiltration is improved in the salivary glands and lacrimal glands following immunization with M3R(208–227) peptide in NOD/LtJ mice, suggesting that peptide immunotherapy using the M3R(208–227) peptide may represent a potential therapeutic alternative.