Abstract 17307: TGR5 Contributes to Improved Perivascular Adipose Tissue Function (PVAT) After Vertical Sleeve Gastrectomy in Mice

Abstract

PVAT is a critical regulator of vascular contractility and its dysfunction contributes to obesity-induced hypertension (HTN). Bariatric surgery, such as vertical sleeve gastrectomy (VSG), causes high rates of HTN remission prior to weight loss, and rescues PVAT function by increasing nitric oxide (NO) production. We have previously validated a VSG mouse model that recapitulates the body weight-independent lowering of blood pressure. VSG increases bile acid (BA) signaling through the BA receptor, TGR5. TGR5 stimulates NO production from endothelial cells (ECs) but the role of TGR5 signaling in adipocyte NO production is unknown. We hypothesized that VSG increases NO bioavailability within PVAT in a TGR5-dependent manner. High fat diet (HFD)-fed male C57BLmice underwent VSG or sham surgery ( n =4-6) Sham (S) mice were food restricted to match body weight to VSG mice. Vascular contractility was reduced in VSG mice (Max contraction (%): S: 30±2, VSG: 23±3; P <0.05). To assess the role of TGR5 on NO production within PVAT, we performed western blotting on mesenteric PVAT from VSG or sham-operated HFD-fed TGR5 WT and KO mice. eNOS phosphorylation was increased in PVAT in VSG WT, but not VSG KO (western blot quantification (AU): S WT: 1.0±0.1, VSG WT: 1.3±0.1, S KO: 1.1±0, VSG KO: 1.0±0.1; P <0.05). To determine how TGR5 regulates PVAT NO production, we assessed the impact of TGR5 on microRNA-21 (miR-21) expression. MiR-21 stimulates NO production in ECs but its role in adipocytes in unknown. Thus, we hypothesized that TGR5 regulates NO production within PVAT by upregulating miR-21. MiR-21 expression was increased in PVAT from VSG-operated TGR5 WT mice but not KO compared to sham controls (western blot quantification (AU): S WT: 0.9±0.1, VSG WT: 2.1±0.5, S KO: 0.7±0.6, VSG KO: 0.6±0.1; P <0.05). We further investigated whether TGR5 activation and miR-21 overexpression stimulate NO production in adipocytes. Mature 3T3-L1 adipocytes were treated with INT-777 or transfected with miR-21 mimic. TGR5 activation and miR-21 overexpression increased eNOS phosphorylation ( P <0.05). In conclusion, our data suggest that VSG increases NO bioavailability in PVAT by activating adipocyte TGR5 signaling and upregulating miR-21 expression.