Abstract 13273: Late Senolytic Therapy Improves Cerebrovascular Endothelial Function but Not Cognition in Middle-Aged Severely Atherosclerotic Mice

Abstract

Introduction: Age-related and atherosclerosis-related vascular dysfunction contributes to neuro-vascular uncoupling, which induces neuronal damage and leads to precocious cognitive loss. This dysfunction could be partially explained by the accumulation of senescent cells (SnC) that remain metabolically active and release many pro-inflammatory factors. Hypothesis: Targeted elimination of SnC with a senolytic restores cerebrovascular function, maintains neuro-vascular coupling and slows cognitive decline. Methods and Results: Nine-month old male atherosclerotic mice (ATX, LDLR -/- ;hApoB +/+ ) were treated (n=13), or not (n=11), for 3 months with navitoclax (50mg/kg), a Bcl2 inhibitor that stimulates global elimination of SnC overexpressing this antiapoptotic pathway. Twelve-month old vehicle-treated ATX mice developed atheroma plaques up to the upper neck portion of the carotid arteries, but not in the cerebral circulation. Three months treatment with navitoclax reduced aortic plaques size (-32%, p<0.001) from 40±2% in vehicle-treated mice to 27±2% in navitoclax mice. At 12 months, endothelial dysfunction was severe in vehicle-treated ATX mice, as evidenced by a strong reduction in flow-mediated dilation (FMD) of pressurized posterior cerebral arteries ex vivo ; navitoclax improved endothelium-dependent dilatation by 50% (for example, FMD at 20 dyn/cm 2 : 58±10%) compared to vehicle-treated mice (FMD: 29±7%; p<0.05). Two cognitive tests were performed: the Y-maze and the novel object recognition tests, to assess exploratory behavior and executive function, respectively. A gradual decline of both exploratory and executive memory was observed from 3 to 6, 9 and 12 months in vehicle-treated ATX mice; navitoclax, however, did not prevent this cognitive decline. Conclusion: Global elimination of SnC slowed atherosclerotic plaque development and restored cerebral endothelial function, demonstrating that senescence contributes to vascular dysfunction. The absence of cognitive improvement with navitoclax suggests an irreversible state of neuronal damage that could not be affected by the late senolytic treatment. To demonstrate the role of SnC in cognitive impairment, an earlier senolytic therapy will be needed.