Effects of muscarinic acetylcholine 3 [receptor.sup.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 Sjogren's syndrome (SS). Autoantibodies against [M3R.sup.208-227] have been shown to interfere with the function of M3R. However, few studies have been performed on the [M3R.sup.205-227] peptide of the second extracellular loop. In the current study, we sought to investigate the effect of [M3R.sup.208-227] peptide immunization on autoimmune response in NOD/LtJ mice. We synthesized the [M3R.sup.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.sup.208-227] peptide in NOD/LtJ mice, suggesting that peptide immunotherapy using the [M3R.sup.208-227] peptide may represent a potential therapeutic alternative.