Abstract 15472: Skeletal Muscle Sirt3 Deficiency Remotely Regulates Pulmonary Vascular Remodeling Via Loxl2-cnpy2-p53 Axis In Pulmonary Hypertension Associated With Heart Failure With Preserved Ejection Fraction

Abstract

Background: Pulmonary hypertension in the context of heart failure with preserved ejection fraction (PH-HFpEF) is the most common cause of PH worldwide. However, major pathways involved in the regulation of PH-HFpEF are still not well understood. We have previously reported a role of skeletal muscle sirtuin-3 (SIRT3) in PH-HFpEF. In the present study, we aimed to investigate how skeletal muscle SIRT3 defects remotely affect pulmonary vascular health in PH-HFpEF. Methods and Results: Using global mass spectrometry-based comparative analysis, we found increased secretion of lysyl oxidase homolog 2 (LOXL2) in SIRT3-deficeint skeletal muscle. Elevated circulation and protein expression levels of LOXL2 were also observed in plasma and skeletal muscle of Sirt3 skm-/- mice, rats with experimental PH-HFpEF (SU5416/Obese ZSF1, Ob-Su), and patients with PH-HFpEF. Additionally, expression levels of canopy fibroblast growth factor signaling regulator 2 (CNPY2), a known angiogenic and proliferative factor, were increased in PASMCs obtained from Sirt3 skm-/- mice and Ob-Su rats, suggesting a potential role of CNPY2 as a molecular target of skeletal muscle SIRT3-LOXL2 signaling in PASMCs. Treatment with LOXL2 recombinant protein resulted in increased levels of CNPY2, PCNA, and cellular proliferation in vitro in PASMCs. LOXL2 treatment, as well as CNPY2 overexpression, decreased the levels of tumor suppressor p53 in PASMCs. In addition, CNPY2 overexpression also decreased CNPY2 expression level in PASMCs. Media conditioned by SIRT3-deficient skeletal muscle cells increased CNPY2 expression in PASMCs, concomitant with decreased p53 and enhanced PCNA. Finally, knockdown of both SIRT3 and LOXL2 in skeletal muscle cells and/or suppression of LOXL2 with β-aminopropionitrile (BAPN) restored CNPY2, p53, and PCNA levels in PASMCs. Conclusions: These studies reveal a new endocrine signaling axis that links skeletal muscle SIRT3 deficiency to remote CNPY2 -p53 regulation in the pulmonary vasculature through myokine LOXL2. Our data may also identify skeletal muscle SIRT3, myokine LOXL2, CNPY2, and p53 as potential targets for the treatment of PH-HFpEF.