Choroid Plexus-Selective Inactivation of Adenosine A2A Receptors Protects Against T Cell Infiltration And Experimental Autoimmune Encephalomyelitis

Abstract

Background: Multiple sclerosis (MS) is one of the most common autoimmune disorders characterized by the infiltration of immune cells into the brain and demyelination. The unwanted immunosuppressive side effect of therapeutically successful natalizumab led us to focus on choroid plexus (CP), a key site for the first wave of immune cell infiltration in experimental autoimmune encephalomyelitis (EAE), for the control of immune cells trafficking. Adenosine A2A receptor (A2AR) is emerging as a potential pharmacological target to control EAE pathogenesis; however, the cellular basis for the A2AR-mediated protection remains undetermined. Methods: In EAE model, we assessed A2AR expression and leukocyte trafficking determinants in CP by immunohistochemistry and qPCR analyses. We determined the effect of the A2AR antagonist KW6002 treatment at days 8-12 or 8-14 post-immunization on T cell infiltration across CP and EAE pathology. We determined the critical role of the CP-A2AR on T cell infiltration and EAE pathology by focal knockdown the CP-A2AR with intracerebroventricular injection of CRE-TAT recombinase into the A2ARflox/flox mice. In cultured CP epithelium, we also evaluated the effect of overexpression of A2ARs or the A2AR agonist CGS21680 treatment on CP permeability and lymphocytes migration. Results: We found the specific upregulation of A2AR in CP in association with enhanced CP gateway activity peaked at day 12 post-immunization in EAE mice. Furthermore, the KW6002 treatment at days 8-12 or 8-14 post-immunization reduced T-cell trafficking across CP and attenuated EAE pathology. Importantly, focal CP-A2AR knockdown attenuated pathogenic infiltration of Th17+ cells across CP via inhibiting CCR6-CCL20 axis through NFκB / STAT3 pathway and protected against EAE pathology. Lastly, activation of A2AR in cultured epithelium by A2AR overexpression or CGS21680 treatment increased the permeability of CP epithelium and facilitated lymphocytes migration. Conclusion: These findings define the CP niche as one of the primary sites of A2AR action whereby A2AR antagonists confer protection against EAE pathology. Thus, pharmacological targeting of the CP-A2AR represents a novel therapeutic strategy for MS by controlling immune cell trafficking across CP.