Activation Of The Adenosine A2A Receptor Attenuates Experimental Autoimmune Myasthenia Gravis Severity

Objective: To investigate the relationship between Adenosine A2A receptor (A2AR)and Experimental Autoimmune Myasthenia Gravis (EAMG); to investigate whetherA2AR activation holds the potential for impacting the severity of EAMG; toinvestigate whether A2AR could impact EAMG severity through impact the banlancebetween four AChR-specific Th subsets.Methods: EAMG were induced following immunization of Lewis rats with theacetylcholine receptor (AChR) R97–116peptide. We used immunohistochemistry totest the A2AR expression in spleen and lymph node. The expression of A2AR onCD4+T cells, CD8+T cells and B cells were detected by FACs analysis. ELISAmethod was used to detect the secretion of anti-AChR antibody in supernatant afterincubation with A2AR agonist CGS21680, A2AR antagonist SCH58261, ZM241385and cAMP antagonist H-89, then the proliferative ability of T lymphocytes wasdetected by3H incorporation. Th subsets distribution was meseasured by FACsanalysis.Results: Compared with CFA control group, the EAMG rats showed lower lever ofA2AR expression in both spleen and lymph node in immunohistochemistryexperiment (Pspleen<0.001, Plymph node<0.05); FACs analysis results turned out thatthe expression of A2AR of EAMG rats were significantly decreased in all CD4+Tcells, CD8+T cells and B cells comprared with CFA group (Pspleen CD4+T cells<0.001, Pspleen CD8+T cells<0.05, PspleenB cells<0.01, Plymph nodeCD4+T cells<0.001, Plymph nodeCD8+T cells<0.01, Plymph nodeB cells<0.05); the secretion of anti-AChR antibody was significantlydecreased after incubation with A2AR agonist CGS21680and this inhibition can beblocked by A2AR antagonist SCH58261, ZM241385and cAMP antagonist H-89 (PCGS21680<0.001, PSCH58261<0.05, PZM241385<0.05, PH-89<0.05). Besides, A2ARactivation could inhibit the proliferation ability of AChR-specific T cells (P <0.05).However A2AR activation had little effect on B cells. We also determined that thedevelopment of EAMG was accompanied by a T helper cell imbalance that could berestored following A2AR stimulation that resulted in increased Treg levels and areduction in Th1, Th2and Th17cell subtypes. An EAMG preventive treatmentregimen was established that consisted of CGS21680(A2AR agonist) administration1day prior to EAMG induction. Administration of CGS2168029days post EAMGinduction (therapeutic treatment) also ameliorated disease severity.Conclusion: A2AR expression is decreased in EAMG progression; A2AR activationhold the potential for impacting the severity of EAMG; A2AR activation hold thepotential for inhibiting AChR-sepecific T cells proliferation and function; A2ARactivation had little effect on B cells and A2AR activation can reversed theimbanlance between Th1/Th2/Th17/Treg subsets. We concluded that A2AR agonistsmay represent a new class of compounds that can be developed for use in thetreatment of MG or other T cell-and B cell-mediated autoimmune diseases.