Abstract Body:
Hypertension (HTN) is a global health condition with significant impacts on morbidity and mortality, often associated with functional and structural changes in perivascular adipose tissue (PVAT) via macrophage infiltration and polarization. PVAT plays a crucial role in modulating vascular function by regulating vascular tone and contractile response. In vitro, RAW 264.7 macrophages treated with CCL5 (100 ng/mL, 24 h) exhibited a pro-inflammatory phenotype, as evidenced by upregulated expression of Il6 (Fold changes: vehicle 1.06 vs. CCL5 7,81*, n:3-5.) and Tnfα (Fold changes: vehicle: 1.02 vs. CCL5: 4,20*, n:3-5). These effects were prevented by co-treatment with maraviroc, a CCR5 antagonist (40 µM) which reduced Il6 and Tnfα expression (Fold changes: 0.93 and 0.95, respectively, n:3-5) indicating that CCL5-induced macrophage activation is CCR5-dependent. Ex vivo, incubation of mesenteric PVAT with Ang II (0.1 µM, 24 h) increased the expression of CCR5 (Fold changes: vehicle: 1.00 vs. Ang II 1.22* and Ang II_Maraviroc: 1.00 n:4-5) and the adhesion molecule VCAM-1 (Fold changes: vehicle: 0.80 vs. Ang II 1.36* and Ang II_Maraviroc: 1.05, n:4-5), suggesting a shift toward a pro-inflammatory state favorable to leukocyte recruitment and CCR5 participation. To extend these findings in vivo, male wild-type (WT) C57BL/6J mice and global CCR5 knockout mice (8–10 weeks old) were treated with either vehicle or Ang II (490 ng/min/kg) for 14 days via osmotic minipumps. Vascular reactivity in mesenteric arteries with (+PVAT) or without (-PVAT) PVAT was assessed using wire myography. In WT mice, PVAT exerted an anti-contractile effect under basal conditions, as shown by reduced phenylephrine (Phe)-induced vasoconstriction [E_max: -PVAT WT 5.5 vs. +PVAT WT 4.7*, n: 3-5. *P<0.05]. However, Ang II treatment eliminated this protective effect [E_max: -PVAT WT_Ang II 6.62 vs. +PVAT WT_Ang II 6.40, n: 3-5]. Notably, this PVAT dysfunction was absent in CCR5 knockout mice treated with Ang II, as their arteries preserved the anti-contractile effect of PVAT [E_max: 3.37 vs. +PVAT WT_Ang II, n: 3-5. #P<0.05]. Our preliminary findings suggest that CCL5/CCR5 signaling contributes to PVAT dysfunction by promoting inflammation and macrophage activation in HTN. However, we still do not know whether macrophage infiltration triggers PVAT dysfunction via CCL5/CCR5.