P2256Aging and inhibition of Nox4 and Nox1 exacerbate perivascular inflammation in spontaneous hypertension

Abstract

Abstract Introduction Hypertension is associated with enhanced NADPH oxidase activation and increased accumulation of immune cells leading to perivascular inflammation. However, while aging and oxidative stress are a major factor for the development of hypertension, their effect on perivascular inflammation remains unclear. Purpose We aimed to establish the interaction between aging, oxidative stress and perivascular inflammation. We hypothesize that the modulation of oxidative stress, by NADPH oxidase inhibition, could affect perivascular inflammation during the aging. Methods Using flow cytometry, we studied leukocyte infiltration in the perivascular adipose tissue (PVAT) in 1-, 3-, 6- and 12-month-old SHR (Spontaneously Hypertensive Rats) and normotensive WKY (Wistar-Kyoto) rats (n=5–12). Additionally, 1-month-old rats were treated with GKT137831 or ML171 (60mg/kg; NOX1/4 and NOX1 inhibitor, respectively) for 4 weeks. Blood pressure (PB) was measured by tail cuff. Statistical analysis was performed using two-way ANOVA or t-test. Data are presented as means±SEM. Results Aging in SHRs was associated with an increase of BP (139±4 vs. 180±4 vs. 203±3 vs. 209±3, mmHg) and an elevation of PVAT leukocytes (2090±164 vs. 2255±359 vs. 2502±496 vs. 3255±408, cell/mg) in 1-, 3-, 6- and 12-month-old rats, respectively. These effects were not seen in WKY. These were associate with similar changes of NK cells (p int <0.001) and macrophages (p int <0.001) in the SHR PVAT. Within T cell compartment, TH17 cells in PVAT were only elevated with age in SHR (1.04±0.08% vs. 1.89±0.2%, 1.08±0.1% vs. 2.03±0.2%, 1.71% vs. 4.37±0.5%, WKY vs. SHR, 3-,6- and 12-months, respectively, p int<0.001). While an age-related increase of Nox4 mRNA in the vessels was observed in both groups, this increase was more dynamic in SHRs, (p int <0.05). Furthermore, 5-, 6- and 9-fold induction of Nox1 mRNA was observed in the vessels of 3-, 6- and 12-months-old SHRs, respectively (p<0.01). Interestingly, GKT137831 increased BP in both WKY and SHR rats (p<0.01, 2-way ANOVA). This was accompanied by the elevation of leukocytes (988±180 vs 147±188 cell/mg, 1487±945 vs 1878±164 cell/mg) and macrophages (107±14 vs. 153±14 cell/mg, 228±26 vs. 298±42 cell/mg) in PVAT of both WKYs and SHRs treated with GKT137831. Moreover, GKT137831 treatment significantly increased (p int<0.01) percentage of TH17 in PVAT of both normotensive (1.4±0.2% vs. 2.5±0.2%) and hypertensive (2.3±0.1% vs. 2.9±0.1%) animals. On the contrary, ML171 treatment, inhibiting only Nox1, in turn protected against an increase of PVAT leukocytes especially among macrophages, TH17 cells (p<0.01). Conclusion Aging and spontaneous hypertension is associated with a trajectory of BP elevation and perivascular inflammation. This state is hastened after NOX1/4 inhibition, while ML171 treatment protects against perivascular inflammation. Acknowledgement/Funding National Science Centre 2013/11/N/NZ4/00310