Abstract P786: Effect of Age and Stroke on Purinergic Receptor P2x4 (p2x4r) Expression in Human Monocyte Subsets

Abstract

Backgrounds: An acute ischemic stroke (AIS) triggers rapid infiltration of circulating immune cells in the brain. P2X4R, a receptor for adenosine triphosphate ATP, regulate activation of circulating monocytes after stroke injury. Over-stimulation of P2X4R contributes to ischemic injury. CD14 ++ CD16 – classical, CD14 ++ CD16 + intermediate, and CD14 + CD16 ++ non-classical monocytes are three primary subsets of monocytes. Alterations in activity of circulating monocyte subsets may independently predict pathogenesis of AIS, however, the role of P2X4R in the activation of these monocyte subsets is not known. Methods: Consecutive AIS patients (60-90 years) undergoing endovascular clot retrieval and healthy control subjects both young (18-45 years) and aged (60-90 years) of both sexes were recruited and informed consent obtained. Flow cytometric analysis of whole blood derived monocytes at 0-2 days (acute, n=10), 3-7 days (subacute, n=9), and 65±20 days (chronic, n=7) after stroke onset were compared with healthy subjects (n=9-10/ age group). Results: Both number of total monocyte counts and P2X4R intensity significantly increase with age when compared between healthy young and aged control (P<0.05). Total monocyte count progressively increased during recovery in AIS patient (P<0.05). No. of CD14 ++ CD16 + intermediate monocytes were significantly reduced after stroke ( p <0.05). Both CD14 ++ CD16 + intermediate, and CD14 + CD16 ++ non-classical monocytes showed a significant increased median fluorescent intensity (P<0.01) of P2X4R at subacute and chronic time after AIS. Conclusions: P2X4R expression increases with age and after stroke. Disappearance of the CD14 + CD16 ++ non-classical monocyte subpopulation from circulation during stroke recovery suggests potential migration of these cells to the site of injury, consistent with their potential role in inflammation/phagocytosis. Increased P2X4R expression in intermediate and non-classical monocytes subpopulation suggest its specific role in selective activation of these monocytes subtype. Detailed molecular characterization of P2X4R response in intermediate and non-classical monocyte subpopulations may provide novel insights into P2X4R’s therapeutic potential during AIS.