Abstract TP242: The Suppression Of Leukocyte Rolling Via Blocking P-selectin After Stroke Is Not Sustained In Mice With Type 2 Diabetes

Abstract

Introduction: Diabetes is associated with worse stroke outcome, yet the mechanism contributing to a more severe ischemic brain injury is not well understood. Neutrophils invade the cerebral veins as early as 30 minutes after stroke and play a major role in acute ischemic brain injury and thrombosis. Leukocyte rolling on the activated endothelium is an early event of transendothelial migration and parenchymal infiltration of leukocytes including neutrophils, which involves p-selectin. The current study sought to determine the effect of blocking p-selectin in reducing leukocyte rolling in the cerebral vessels of diabetic mice after stroke. Methods: Stroke was induced in 4-month old diabetic db/db and control db/+ mice via middle cerebral artery occlusion (MCAO). P-selectin blocking antibody (P-aby) was administered intravenously 30 min after MCAO at 20 mg/kg. Adherent or rolling leukocytes was quantified at baseline before MCAO and after ischemic reperfusion by repeated 2-photon microscope imaging with fluorescent tracers. Infiltrating neutrophils and plasma soluble p-selectin were determined via FACS and ELISA, respectively. Results: Leukocyte rolling was immediate detected in the veins 1 hr after reperfusion and significantly increased 1d after MCAO in both genotypes of mice. Rolling tended to last days longer in the db/db compared to db/+ mice, and was often seen in the arterioles of the former but not in the latter mice. Increased infiltration of neutrophils was detected in db/db compared to db/+ brain parenchyma 1-3 ds after MCAO by FACS. Three to 5 fold-reduction in rolling by was detected 1 hr after reperfusion in both genotypes following P-aby treatment. However, rolling resumed in db/db mice 1 d after MCAO and antibody treatment, compared to a sustained suppression of rolling seen in the db/+ mice till days later. Elevated soluble p-selectin was also detected in the plasma of db/db compared to db/+ mice. Conclusions: Stroke-induced leukocyte rolling was only temporarily suppressed by P-selectin blocking antibody in db/db mice. Ongoing studies will determine the effect of P-selectin blocking on microthrombi formation, cerebral blood flow, neuroprotection and the role of soluble p-selectin in dampening the treatment effect.