Mechanisms of Vascular Dysfunction in COPD and Effects of a Novel Soluble Epoxide Hydrolase Inhibitor in Smokers.

Abstract

$\textbf{BACKGROUND}$: Smoking and chronic obstructive pulmonary disease (COPD) are risk factors for cardiovascular disease, and the pathogenesis may involve endothelial dysfunction. We tested the hypothesis that endothelium-derived epoxyeicosatrienoic acid (EET)-mediated endothelial function is impaired in patients with COPD, and a novel sEH inhibitor GSK2256294 attenuates EET-mediated endothelial dysfunction in human resistance vessels both $\textit{in vitro}$ and $\textit{in vivo}$.

$\textbf{METHODS}$: Endogenous and stimulated endothelial release of EETs was assessed in 12 COPD patients, 11 overweight smokers, and 2 matched control groups, using forearm plethysmography with intra-arterial infusions of fluconazole, bradykinin, and the combination. The effects of GSK2256294 on EET-mediated vasodilatation in human resistance arteries were assessed $\textit{in vitro}$ and $\textit{in vivo}$ in a Phase 1 clinical trial in healthy overweight smokers.

$\textbf{RESULTS}$: Compared to controls, there was reduced vasodilatation to bradykinin (p=0.005), blunted effect of fluconazole on bradykinin-induced vasodilatation (p=0.03), and a trend towards reduced basal EET/DHETs ratio in COPD patients (p=0.08). A similar pattern was observed in overweight smokers. $\textit{In vitro}$, 10 μM GSK2256294 increased 11,12-EET-mediated vasodilatation compared to vehicle (90±4.2% vs. 72.6±6.2% maximal dilatation), and shifted the bradykinin EC50 (-8.33±0.172 vs. -8.10±0.118 logM; p=0.001 for EC50). $\textit{In vivo}$, 18 mg GSK2256294 improved the maximum bradykinin response from 338±46% pre-dose to 566±110% post single dose (p=0.02), and to 503±123% post chronic dose (p=0.003).

$\textbf{CONCLUSION}$: GSK2256294 attenuates smoking related EET-mediated endothelial dysfunction, suggesting potential therapeutic benefits in patients with COPD.