Low-dose colchicine treatment improves vasorelaxation, reduces arterial remodeling and attenuates blood pressure increases in spontaneously hypertensive rats
Colchicine, a microtubule depolymerizing agent, is an effective therapy for the secondary prevention of cardiovascular disease and has been approved recently as a novel treatment for atherosclerosis associated with coronary artery disease. Hypertension is a leading cause of cardiovascular disease, yet the impact of colchicine on hypertension has not been studied. We hypothesized that low-dose colchicine could be used to treat hypertension to reduce cardiovascular disease risk. The aim of this study was to administer daily, low dose (0.05 mg/kg/day) oral colchicine for 4 weeks to spontaneously hypertensive rats (SHR) and normotensive controls (WKY) and determine the effect on blood pressure, vascular reactivity, remodeling and inflammation, and left ventricular hypertrophy. Daily blood pressure measurements recorded by telemetry in conscious rats showed colchicine prevented increases in mean arterial pressure observed in the SHRs receiving vehicle over the 4-week treatment period. After the 4-weeks of treatment, 3rd order mesenteric artery vasorelaxations to isoproterenol, sodium nitroprusside and the Kv7.2-5 channel activator, ML213, were enhanced in the SHRs receiving colchicine compared to vehicle. The improved isoproterenol-mediated relaxation was also observed in WKY rats receiving colchicine, and in both the SHR and WKY, this improved effect was attenuated by the {beta}2 adrenoceptor antagonist, ICI118,551. Proteomic analysis of the mesenteric arteries by mass spectrometry revealed that colchicine treatment prevented changes observed when comparing the SHR vehicle group with the WKY vehicle group in proteins associated with extracellular matrix pathways. Immunostaining of 3rd order mesenteric arteries with Sirius red found that colchicine treatment attenuated the increased media thickness of the artery wall observed in SHRs receiving vehicle. Multiplex immunoassay and Western blots revealed colchicine reduced certain inflammatory mediators in the wall of the SHR mesenteric arteries, particularly the nucleotide-binding domain and leucine-rich repeat pyrin containing protein-3 (NLRP3), IL-18, CXCL10, and CXCL2, as well as reducing phosphorylated STAT3. Finally, in the left ventricle of the SHR, colchicine treatment attenuated a number of inflammatory mediators, including NLRP3, IL-1{beta}, and IL-18, and reduced fibrosis and cell size, which are indicative of left ventricular hypertrophy. Overall, we show colchicine has the potential to elicit cardiovascular protective effects in hypertension by targeting multiple cell types.