Abstract DP197: Blockade of VCAM1 or VLA4 promotes normal cerebrovasculature and prevents cognitive decline late after stroke

Introduction: Infarct-induced neurodegeneration occurs chronically after stroke, doubling the risk of dementia. Vascular cell adhesion molecule 1 (VCAM1) facilitates blood-brain barrier (BBB) opening and immune cell diapedesis by binding very late antigen 4 (VLA4). We hypothesized that elevated VCAM1 persists after stroke and contributes to vascular dysfunction and cognitive decline. Methods: VCAM1 was measured in plasma from 106 humans with chronic stroke (median 10 mo) and 212 healthy controls matched for age, sex, and sample storage time using two SomaLogic aptamers. Adult (3 mo) and middle-aged (10 mo) C57BL/6J male&female mice (N=9-10/group) underwent permanent middle cerebral artery occlusion and were dosed with anti-VCAM1, anti-VLA4 or isotype control every 3 days beginning 4 days after stroke. Barnes maze and novel object were performed at -1, 1 and 6 weeks, and scRNASeq was performed on immune and endothelial cells at 10 weeks. We quantified vessel length, pericyte (CD13) coverage of vasculature (CD31), tight junctions (ZO-1), and extravascular fibrinogen with immunostaining. Results: VCAM1 was elevated in plasma of humans with chronic stroke by 10-13% (p<0.0001, both aptamers) and further in those with worse cognitive trajectory (p=0.02). Mouse vasculature exhibited elevated VCAM1 (p=0.0352), and decreased BBB integrity at 8 weeks after stroke with reduced ZO-1 (50%, p=0.0133), pericyte coverage (35%, p= 0.016), and increased extravascular fibrinogen (p=0.0057). Stroked mice developed a cognitive deficit in both Barnes maze and novel object by 6 weeks, while sham and stroke anti-VCAM1 and VLA4 all performed the Barnes Maze and novel object normally (p<0.0059-<0.0001 compared to stroke-isotype control). Anti-VCAM1 and anti-VLA4 both increased expression of pro-angiogenesis genes ( sox18 , klf4 ) and BBB maintenance genes ( cldn5, ocln, lama2 ) in brain endothelial cells. In addition, both antibodies increased blood vessel length and pericyte vascular coverage by 67% (p=0.0113) and 65% (p=0.0215), respectively. Finally, extravascular fibrinogen was reduced 18% by anti-VCAM1 (p=0.031) and 15% by anti-VLA4 (p=0.0493). Conclusion: Together, our findings establish the VCAM1-VLA4 axis as a promising target to prevent cognitive decline late after stroke. Our data is consistent with a model where blocking either VCAM1 or VLA4 promotes angiogenesis, restores the BBB, and decreases inflammation to prevent infarct-induced neurodegeneration after stroke.