The Fifth Element: Is Vascular Dysfunction an Intrinsic Feature of Gout?

Abstract

Gout, the most common inflammatory arthritis, affects as many as 5.1% of the adult population. Classically, gout is conceived as four sequential phenotypic states: 1) asymptomatic hyperuricemia 2) acute gout flare 3) inter-critical gout (gout between flares); and 4) tophaceous gout. However, these four states are paralleled by a fifth state, consisting of vascular involvement. The mechanisms and consequences of vascular gout are incompletely elucidated. In vitro and animal models indicate that soluble urate adversely affects vascular endothelium and smooth muscle. The recent discovery that soluble urate can be transported intracellularly to alter cell metabolism and epigenetics (trained innate immunity) suggests additional impacts of urate on leukocytes and endothelium. Once gout has progressed to flares, the vasculature is exposed to inflammatory mediators, both during flares and to a lesser but persistent extent inter-critically, suggesting additional mechanisms of gout's effect. We have reported that patients with gout have diminished endothelial function measured by brachial artery flow-mediated dilation. ACR gout guideline-concordant treatment improves endothelial function but is less effective in patients with cardiometabolic comorbidities. Moreover, treatment of gout patients with the anti-inflammatory colchicine and urate lowering therapy improves endothelial function and reduces the risk of both incident coronary artery disease (CAD), and MACE in patients with established CAD.