Abstract P480: Myeloid YAP Inhibition Improves Cardiac Phenotype During Pressure Overload Stress

Abstract

Inflammation is a component of cardiovascular disease and is thought to contribute to cardiac dysfunction in ischemic and non-ischemic models of heart failure. While ischemia-induced inflammation has been extensively studied in the heart, relatively less is known regarding cardiac inflammation during non-ischemic stress. Recent work has implicated a role for Yes-associated protein (YAP), a transcriptional co-factor, in modulating cardiac inflammation and remodeling after myocardial infarction. We hypothesized that YAP mediates a pro-inflammatory response during pressure overload (PO)-induced non-ischemic injury, and that targeted YAP inhibition is cardioprotective. PO in mice elicits an immune response characterized by infiltration of myeloid cells that precedes cardiac dysfunction. Myeloid cells isolated from the heart after 7d PO showed evidence of increased YAP activity. Myeloid-specific YAP knockout mice (YAP F/F ;LysM Cre ) were subjected to PO stress. After 4 weeks, cardiac hypertrophy was similar between YAP KO mice and controls. However, systolic dysfunction, cardiac fibrosis, and indicators of pathological remodeling were all attenuated in YAP KO mice compared to controls. Additionally, inflammatory gene expression and macrophage infiltration to the myocardium were significantly attenuated in YAP KO mice after PO, indicating reduced inflammation compared to controls. Experiments using RAW264.7 macrophages and primary bone marrow-derived macrophages (BMDMs) from YAP KO and control mice demonstrated that increased YAP expression enhanced, while YAP suppression attenuated, inflammatory gene expression. The inflammasome is a multiprotein complex and important facilitator of cytokine processing that mediates inflammation in the PO heart. We observed attenuated inflammasome priming and function in YAP deficient BMDMs, as well as in YAP KO hearts following PO, indicating disruption of inflammasome induction. Together these data implicate YAP as an important mediator of inflammasome function and cardiac inflammation during PO stress and suggest that selective inhibition of YAP in the myeloid compartment may prove a novel therapeutic target in non-ischemic heart disease.