Abstract 100: Activation Of The Skin Renin-angiotensin System Contributes To The Development Of Hypertension

Abstract

Recent studies suggest skin vasoconstriction and sodium (Na + ) accumulation are associated with hypertension. The skin has a localized renin-angiotensin system (RAS), a key regulator of blood pressure (BP), but its functional role remains unclear. This study aims to investigate the role of skin RAS in hypertension. Skin tissue from 32 individuals, including patients with hypertension, was used to evaluate the association between skin RAS component expression and office BP. Among the RAS components, skin expression of ATRAP (type-1 angiotensin II (Ang II) receptor (AT1R)-associated protein), which selectively inhibits pathological AT1R signaling, was inversely correlated with systolic and diastolic BP (R 2 = 0.12, P < 0.05; R 2 = 0.20, P < 0.05, respectively). To investigate the causal relationship between skin ATRAP and hypertension, mice lacking ATRAP in skin keratinocytes (KO: K14 Cre ;ATRAP flox ) were generated. Telemetry analysis showed that Ang II (500 ng/kg/min)-induced hypertension and related cardiac hypertrophy was exacerbated in KO mice compared to control mice (mean BP, 123.3 ± 4.7 vs. 132.6 ± 3.1 mmHg, n = 5, P < 0.05; heart/body weight, 4.7 ± 0.4 vs. 5.2 ± 0.7, n = 11-12, P < 0.05). KO mice showed increased skin expression of angiotensinogen and AT1R ( P < 0.05 for each; n = 11-12), while those in the kidneys and heart were similar in both groups, suggesting skin-specific enhancement of tissue RAS activity. AT1R blocker treatment eliminated exaggerated Ang II-induced hypertension and enhancement of skin RAS activity in KO mice. Sympathetic nerve activity, plasma volume, and skin Na + content did not differ between the groups. In KO mice, urine volume per water intake increased ( P < 0.001), despite similar body weight changes in both groups, suggesting decreased extra-renal water loss. Consistent with these findings, skin blood flow (22.6 ± 3.8 vs. 16.5 ± 4.5 AU, P < 0.001) and transepidermal water loss (9.0 ± 1.9 vs. 6.5 ± 1.9 g/m 2 /h, P < 0.01) were decreased in KO mice. These differences, including exaggerated Ang II-induced hypertension, were eliminated by skin vasodilation via body temperature elevation. In conclusion, enhanced skin RAS activity contributes to BP elevation via skin vasoconstriction. Skin RAS may be a novel target for treating hypertension.