The potent and selective adenosine A2AR antagonists P400 and P625 protect against symptoms in autoimmune experimental encephalomyelitis by attenuating neuroinflammation and demyelination

Multiple sclerosis (MS) is an autoimmune chronic inflammatory disease of the central nervous system characterized by oxidative stress, demyelination, and neuronal damage. Current MS therapies are unsatisfactory and new therapies are encouraged. Adenosine is highly implicated in MS as it regulates, via activation of its A_2A receptor (A_2AR), the inflammatory and immune response. The aim of this study is to investigate the therapeutic potential of new selective A_2AR antagonists, P400 and P625, in the experimental autoimmune encephalomyelitis (EAE), the principal animal model of MS. P400 and P625 administration (10 μg/mouse intranasal) for 14 days reduced motor disability (clinical score, rotarod) and thermal (hot plate) and mechanical (von Frey) hypernociceptive symptoms associated with a chronic MS model. Quantitative analysis of lymphocytes infiltration in the spinal cord sections stained with hematoxylin and eosin (H&E) showed a larger number of inflammatory cells in EAE sections that were markedly reduced by P400 and P625. P400 also reduced the immunostaining of Iba1, marker of microglia. Luxol Fast Blue (LFB) staining and myelin basic protein (MBP) immunostaining of spinal cord sections showed a robust loss of myelin that was partially restored by P400 and P625. Both treatments increased spinal neurofilament H (NfH) and GAP43 protein expression compared to untreated immunize mice. These data illustrate the efficacy of the new selective A_2AR antagonists in ameliorating EAE symptoms by attenuating neuroinflammation and demyelination. These findings further highlight A_2AR blocking as a promising perspective to control neurological disturbances in MS patients.