Inactivation of the Phosphatase Activity of Soluble Epoxide Hydrolase Modulates SIRT3 and Attenuates Experimental Pulmonary Hypertension

INTRODUCTION: Pulmonary hypertension (PH) is a severe cardiovascular disorder characterized by elevated pulmonary artery pressure caused by remodeling of the pulmonary circulation. This study aimed to investigate the role of the soluble epoxide hydrolase phosphatase domain (sEH-P) in PH pathogenesis. METHODS: The effects of sEH-P genetic inactivation were evaluated in vivo using a CRISPR/Cas9-mediated approach in two rat modes of PH: the monocrotaline and the Sugen/hypoxia model. To further explore the underlying mechanisms, complementary in vitro experiments were conducted in cultured human pulmonary artery smooth muscle cells (PA-SMCs), where sEH expression was modulated. RESULTS: sEH-P inactivation attenuated experimental PH in both rat models, as demonstrated by reductions in mean pulmonary artery pressure and total pulmonary vascular resistance. Histological analysis showed decreased pulmonary artery muscularization and reduced collagen deposition in the right ventricle. Moreover, sEH-P inactivation reduced sEH protein levels and enhanced SIRT3 expression in the lungs. Two-hybrid interaction assays suggested that sEH indirectly regulates SIRT3 expression. In cultured human PA-SMCs, altering sEH levels influenced SIRT3 expression, cell proliferation, and the levels of FoxO1, BCL2, and Bax proteins. In sEH-P KI rat lungs, FoxO1 levels increased, while anti-apoptotic BCL2 protein decreased. CONCLUSIONS: Our findings underscore the role of sEH-P in the development and progression of PH, partly through its regulation of SIRT3 expression, cell proliferation, and apoptosis-related proteins. Targeting sEH-P emerges as a promising therapeutic strategy for PH.