O100 IL15RA MEDIATES BLOOD PRESSURE ELEVATION, INFLAMMATION AND VASCULAR DAMAGE IN ANGIOTENSIN II-INDUCED HYPERTENSION

Abstract

Cytokines are key mediators regulating blood pressure (BP) and target organ damage in hypertension. IL15 levels increase in cardiovascular diseases, but the role of IL15 and its receptor alpha (IL15R) in hypertension and hypertension-mediated inflammation and vascular damage is still unknown. Wild-type and IL15Rα-/-mice (n=5-9) were infused with vehicle or angiotensin II (AngII, 490ng/min/kg). Recombinant IL15 was administered to WT mice (1ug, daily, 14 days) during AngII infusion. Telemetry, wire myography, luminometry, PSR staining, qPCR, immunoblotting, flow cytometry, and primary cell lines were used. Hypertensive patients have increased levels of IL15Rα in arteries, which significantly correlated with systolic (r=0.33, p=0.002), diastolic (r=0.27, p=0.02) pressure and maximal constriction to phenylephrine ex vivo (r=0.27, p=0.03). Similarly, AngII infusion significantly increased serum IL15/IL15Rα (8.8±0.7pg/ml vs 12.1±0.7pg/ml, p<0.01), IL15Rα mRNA (1±0.1 vs 1.8±0.1, p<0.01) and protein (1±0.03 vs 1.8±0.28, p<0.01) levels in the aortas. BP lowering using hydralazine and hydrochlorothiazide treatment prevented these changes in vasculature. IL15Rα was induced by pathophysiological stretch (15%) or interferon-gamma in adventitial fibroblasts, vascular smooth muscles, and endothelial cells in vitro. In contrast, AngII, other inflammatory cytokines or oxidative stress mediators have no such direct effect. Il15Rα-/- blunted AngII-induced hypertension (199±5.6mmHg vs 148±7.3mmHg, p<0.001), protected against endothelial dysfunction (p<0.01) and aortic superoxide production (59.4±7.8 vs 36.4±7.6 RLU/sec/mg) compared to wild-type mice. This was accompanied by reduced perivascular inflammation, lack of immune cell recruitment and effector and memory T cell formation. Similarly, T cell interferon-gamma and interleukin-17 production was attenuated in Il15Rα-/- hypertensive mice. In contrast, simultaneous administration of AngII and rIL15 into WT mice enhanced these outcomes. Perivascular fibrosis was observed in WT, but not Il15Rα-/- hypertensive animals (111036±19117 μm2 vs 48689±5515 μm2, p<0.01) and was in line with significantly lower mRNA of collagen and fibronectin protein levels in Il15Rα-/- aortas. IL15Rα plays a crucial role in immune activation, vascular damage, and AngII-induced hypertension. Targeting this pathway may offer potential therapeutic benefits for controlling hypertension and preventing associated vascular complications.