Impact of the modulation of Soluble epoxide hydrolase enzymatic Activities on Pulmonary HypertensIon and Right ventricular dysfunction in experimental and human heart failure – SAPHIR

Despite major therapeutic advances, the worsening heart failure (HF) epidemic and the associated healthcare costs represent a major burden to public health and the healthcare system. This is notably related to the lack of pharmacological strategies targeting the development of pulmonary hypertension (PH) and associated right ventricular (RV) dysfunction, which are known to markedly aggravate HF. Soluble epoxide hydrolase (sEH) primarily metabolizes epoxyeicosatrienoic acids (EETs), which are protective vasodilating eicosanoids in the systemic circulation but that ma exert deleterious effects in the pulmonary vasculature. Moreover, sEH has also a phosphatase domain whose lipid substrates and function remain poorly investigated, although indirect evidences suggest its role in PH development through the metabolism of cholesterol precursors and lysophosphatidic acids (LPAs). The aim of this translational project is to assess whether the modulation of sEH enzymatic activities may be useful to treat PH and RV dysfunction in a context of HF.
In absence of specific pharmacological agents, the effects of the inactivation and overexpression of sEH phosphatase will be assessed using original animals models developed by the Transgenic Rats and Immunophenomic Platform in Nantes (TRIP, Partner 3), based on the CRISPR-Cas9 technology. Moreover, sEH knock-out rats, lacking both activities and a pharmacological inhibitor of the hydrolase domain developed by the University of California Davies (Partner 4) will be used. To further evaluate and confirm the role of each sEH-associated enzymatic activities, recombinant adeno-associated viral vector of serotype 9 will be injected to mediate cardiac transgenic expression of mutated sEH forms retaining either the sole phosphatase or hydrolase activity. Ischemic HF associated with PH and RV dysfunction will be induced in rats by definitive coronary artery ligation, and two complementary models of PH without HF (monocrotaline and sugen+hypoxia) will be used to assess the impact of sEH modulation independently from its effects on the left heart. RV and left ventricular (LV) function and dimension will be assessed by magnetic resonance imaging, echocardiography and invasive hemodynamics within the cardiovascular imaging platform of INSERM U1096 (Partner 1) and INSERM U999 (Partner 2). Vascular reactivity will be assessed in coronary and pulmonary arteries by myography. Infarct size, indices of LV and RV hypertrophy, collagen and capillary densities, inflammation, oxidative stress, sEH activities and molecular pathways regulated by cholesterol precursors and LPAs will be also determined.
In parallel, a clinical study conducted by the Departments of Pharmacology and Cardiology, members of INSERM U1096 at Rouen University Hospital will investigate the association between single nucleotide polymorphisms of the sEH gene, taking into consideration their effects on sEH hydrolase and/or phosphatase activities, and the clinical characteristics of HF patients, notably the presence of PH assessed by catheterization and echocardiography.
Finally, transcriptomic and phosphoproteomic approaches applied to rat cardiac tissues and mononuclear cells isolated from genotyped HF patients will be used to further determine the substrates and function of the sEH lipid phosphatase. EETs, cholesterol precursors, LPAs and their metabolites will be determined in rat and human plasma by newly developed LC-MS/MS analysis.
This translational project based on an established network of complementary disciplines, with leading international research groups (HF and small animal imaging for INSERM U1096, PH for INSERM U999, transgenic approaches in rats for the TRIP and sEH biochemistry for the University of California) should demonstrate that the modulation of enzymatic activities of sEH represents an attractive pharmacological target to treat PH secondary to left-sided heart disease, for which no treatment is currently available.