Abstract MP151: Cardiomyocyte HIPK2 is a Critical Regulator of Purinergic Signaling Regulated Myocardial Inflammation

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Objective: Heart failure (HF) is a major and growing public health problem worldwide. Recently our lab has identified HIPK2 as an essential kinase to maintain basal cardiac function. However, the role of cardiomyocytes specific HIPK2 (CM-HIPK2) in myocardial inflammation is unknown. Methods: α-MHC promoter-driven, Cre mice were crossed with HIPK2 fl/fl mice to generate CM-HIPK2 KO. Echocardiography was performed to assess cardiac function. Immunoblotting assays were performed to determine the expression of HIPK2, CD39, CD73, and other signaling pathway . Flow cytometry and ELISA were performed to study the dynamics of inflammation. Results: Consistent with our previous report , echocardiography confirmed an impaired cardiac function in 3 months old CM-HIPK2 KO as compared to their littermate controls. Importantly, cardiac function in the KOs starts to deteriorate at ~2.5 months of age, thus, at two months of age, the cardiac function of KO and littermate control was comparable. Comprehensive immune profiling of CM-HIPK2 KO and littermate control hearts were performed at two months of age. We observed an increased frequency of infiltrated CD45 + leukocytes, CCR2 + pro-inflammatory macrophages, Th17 + , Th9 + , CD45 + TNFα + , CD45 + IL1β + , CD45 + Ki67 + cells but diminished frequency of Myeloid-derived suppressor cells (MDSCs), TCRαβ + CTLA-4 + and TCRαβ + PD-1 + in the CM-HIPK2 KO hearts. Mechanistically, we observed a significantly reduced expression of CD39 and CD73 over HIPK2 deleted cardiomyocytes. Indeed, CD39 and CD73 are the key players of purinergic signaling regulated inflammation response. In-vitro studies with neonatal rat ventricular cardiomyocytes (NRVMs) corroborated the in-vivo findings. Specifically, adenovirus-mediated overexpression of HIPK2 significantly increased CD39 expression. Consistently, Ad-shRNA-HIPK2 expression suppressed the CD39 expression. Taken together, our findings suggest a critical role of CM-HIPK2 in purinergic signaling mediated myocardial inflammation. Conclusions: CM-HIPK2 maintains basal cardiac function by controlling purinergic signaling regulated myocardial inflammation. Future work will explore the underlying mechanism of HIPK2 mediated regulation of CD39 and CD73.