Abstract 4145109: Disturbed Flow (d-flow)-induced Endothelial Senescence-Associated Stemness (SAS): Unveiling the Impact of CD38 and LATS1/2 Depletion on Atherothrombosis Development

Background: Atherosclerotic plaques, especially high-risk ones, form in blood vessel regions exposed to d-flow. EC dysfunction induced by d-flow likely contributes to plaque development. In contrast, regions with laminar flow (l-flow) are less susceptible to plaque formation. Although the Hippo pathway is implicated in mechano-transduction, the exact role and molecular mechanisms of LATS1/2 in response to d-flow remain incompletely understood. Methods: We employed endothelial cell (EC)-specific Lats1 and Lats2 knockout mice within a partial left carotid ligation (PLCL) model to simulate disturbed flow conditions. We characterized plaques using imaging mass cytometry (IMC) and sequential immunofluorescence via COMET TM . Results: We investigated the effects of d-flow on YAP activity and LATS1/2 expression. While both l-flow and d-flow activate YAP activity, only d-flow leads to decreased LATS1/2 expression. We induced Lats1/2 deletion in tamoxifen-inducible Lats1 -/- /Lats2 -/- EKO mice. Within 14 days, all mice (27/27) died due to severe systemic edema and increased vascular permeability. In Lats1 +/- /Lats2 -/- EKO mice (LATS1/2-EKO), we observed atherothrombotic lesions characterized by increased EC proliferation and a senescence-associated secretory phenotype (SASP) in vivo . Mechanistically, d-flow reduces LATS1/2 expression, leading to increased CD38 expression. CD38 triggers not only SASP, but also senescence-associated stemness (SAS) via NAD + depletion, dependent on Lamin A but independent of YAP. We also explored the relationship between CD38 and Ki67 in plaques in vivo. We calculated the logarithm of the Ki67:CD38 expression ratio at the single-cell level using IMC/COMET data. Based on the trimodal density distribution of this parameter, we found that in one group, CD38 and Ki67 were linearly co-expressed, and the percentage of LATS1/2-depleted cells in this group exceeded that of wild type (WT) cells, suggesting that CD38’s pro-proliferative effects dominate under LATS1/2 depletion conditions, despite its role in inducing senescence. Lastly, inhibiting CD38 mitigated d EC SAS/SASP, and atherothrombosis under LATS1/2 depletion conditions. Conclusions: Reduced LATS1/2-mediated CD38 expression in response to d-flow leads to an EC response marked by increased SASP/SAS, ultimately contributing to atherothrombosis. While this phenomenon is common in human advanced coronary atherosclerosis, it is not observed in commonly used mouse models of atherosclerosis.