Pharmacological blockade of the 20‐HETE receptor (GPR75) lowers blood pressure and alters vascular remodeling in mice with vascular smooth muscle‐specific overexpression of CYP‐4a12‐20‐HETE synthase
Authors: Agostinucci Kevin , Gilani Ankit , Hossain Sakib , Pascale Jonathan , Zhang Frank , Falck John R. , Garcia Victor , Schwartzman Michal Laniado 
Published: April 2020

20‐hydroxyeicosatetraenoic acid (20‐HETE) is a vasoactive eicosanoid of the microcirculation exhibiting effects on vascular smooth muscle (VSM) function that include stimulation of smooth muscle contractility, migration, and growth. The aim of this study is to assess the consequences of VSM‐targeted overexpression of Cyp4a12, the primary 20‐HETE producing enzyme in mice, on blood pressure, vascular function, and vascular remodeling, and examine whether administration of a 20‐HETE receptor antagonist reverse the phenotype of these mice. Mice with VSM‐specific overexpression of Cyp4a12 (Myh11‐4a12) and their littermate controls (WT) were generated by crossbreeding Cyp4a12‐floxed mice with Myh11‐Cre mice. Male Myh11‐4a12 and WT were administered AAA, a 20‐HETE receptor antagonist, in the drinking water at a dose of 10mg.kg−1.day−1. Experiments were carried out for 12 days. Systolic blood pressure (SBP) was measured by tail cuff. At the end of the experiments, renal interlobar (RIA) and mesenteric arteries were harvested for assessment of 20‐HETE levels measured by LC‐MS/MS, and vascular contractility, vasodilation, and remodeling using wire and pressure myography. The Myh11‐4a12 mice showed higher CYP4a levels in mesentery arteries compared to WT mice (6.5±0.71 vs 3.4±0.70; p<0.05). Myh11‐4a12 mice had increased 20‐HETE levels in the mesentery (3334±891 vs. 545±197 pg/mg protein; p<0.05) and RIA (1859±376 vs 242±62 pg/mg protein; p<0.05), but, urine 20‐HETE levels were not different (117±9 vs. 93±2 pg/mL; p=0.18) when compared to WT. Myh11‐4a12 mice displayed higher SBP compared to WT mice (145±2 vs. 127±2 mmHg; p<0.05). Administration AAA for 12 days normalized BP in Myh11‐4a12 mice (124±2 mmHg vs. 147±4 mmHg, p<0.01). Blood pressure in WT on either AAA (127±5 vs. 123±6 mmHg; p=0.94) or regular water (128±3 vs 126±2 mmHg; p=0.98) did not change during the treatment period. After 12 days of treatment, RIA from Myh11‐4a12 on regular water displayed a higher media to lumen ratio (0.335±0.033 vs 0.187 ± 0.007; p<0.01) and cross sectional area (CSA) (20024±2050 vs 13031±592 μm2; p<0.01) compared to WT on regular water. RIA from Myh11‐4a12 mice on AAA appeared to have a lower media to lumen ratio compared to Myh11‐4a12 mice on regular water (0.259 ± 0.012 vs 0.358 ± 0.033; p=0.053), but CSA was not different (19664 ± 761 vs 20024 ± 2050 μm2; p=0.98). RIA from Myh11‐4a12 mice displayed higher constrictor responsiveness to phenylephrine (EC50: 0.09 ± 0.02 vs 0.77 ± 0.23 μM, p<0.0001) and impaired relaxation to acetylcholine (Maximum response at 10−4 M: 65 ± 1 vs 83 ± 2 % relaxation, p<0.001) as compared to WT. Treatment of Myh11‐4a12 mice with AAA diminished the constrictor responsiveness to phenylephrine (EC50 of 0.37 ± 0.06 μM, p<0.0001) and the impaired relaxation to acetylcholine (92 ± 2 % relaxation, p<0.001). Taken together, these data indicate that VSM‐specific overexpression of Cyp4a12 increases blood pressure and causes hypertrophic vascular remodeling in a 20‐HETE‐dependent manner.Support or Funding InformationNIH grants HL39793 (MLS), HL39793‐01S1 (VG) and NIH (Z01 ES025034 (DCZ)).