Abstract-Angiotensin (Ang) II induces hypertension by mechanisms mediated in part by adaptive immunity and T effector lymphocytes. T regulatory lymphocytes (Tregs) suppress T effector lymphocytes. We questioned whether Treg adoptive transfer would blunt Ang II-induced hypertension and vascular injury. Ten-to 12-week-old male C57BL/6 mice were injected IV with 3ϫ10 5 Treg (CD4 ϩ CD25 ϩ ) or T effector (CD4 ϩ CD25 Ϫ ) cells, 3 times at 2-week intervals, and then infused or not with Ang II (1 g/kg per minute, SC) for 14 days. Ang II increased systolic blood pressure by 43 mm Hg (PϽ0.05), NADPH oxidase activity 1.5-fold in aorta and 1.8-fold in the heart (PϽ0.05), impaired acetylcholine vasodilatory responses by 70% compared with control (PϽ0.05), and increased vascular stiffness (PϽ0.001), mesenteric artery vascular cell adhesion molecule expression (2-fold; PϽ0.05), and aortic macrophage and T-cell infiltration (PϽ0.001). All of the above were prevented by Treg but not T effector adoptive transfer. Ang II caused a 43% decrease in

Aldosterone mediates actions of the renin-angiotensin-aldosterone system inducing hypertension, oxidative stress, and vascular inflammation. Recently, we showed that angiotensin II-induced hypertension and vascular damage are mediated at least in part by macrophages and T-helper effector lymphocytes. Adoptive transfer of suppressor T-regulatory lymphocytes (Tregs) prevented angiotensin II action. We hypothesized that Treg adoptive transfer would blunt aldosterone-induced hypertension and vascular damage. Thirteen to 15-week-old male C57BL/6 mice were injected intravenously at 1-week intervals with 3×10(5) CD4(+)CD25(+) cells (representing Treg) or control CD4(+)CD25(-) cells and then infused or not for 14 days with aldosterone (600 μg/kg per day, SC) while receiving 1% saline to drink. Aldosterone induced a small but sustained increase in blood pressure (P<0.001), decreased vasodilatory responses to acetylcholine by 66% (P<0.001), increased both media:lumen ratio (P<0.001) and media cross-sectional area of resistance arteries by 60% (P<0.05), and increased NADPH oxidase activity 2-fold in aorta (P<0.001), kidney and heart (P<0.05), and aortic superoxide production. As well, aldosterone enhanced aortic and renal cortex macrophage infiltration and aortic T-cell infiltration (all P<0.05), and tended to decrease Treg in the renal cortex. Treg adoptive transfer prevented all of the vascular and renal effects induced by aldosterone. Adoptive transfer of CD4(+)CD25(-) cells exacerbated aldosterone effects except endothelial dysfunction and increases in media:lumen ratio of resistance arteries. Thus, Tregs suppress aldosterone-mediated vascular injury, in part through effects on innate and adaptive immunity, suggesting that aldosterone-induced vascular damage could be prevented by an immunomodulatory approach.

γδ T cells mediate Ang II-induced SBP elevation, vascular injury, and T-cell activation in mice. γδ T cells might contribute to the development of hypertension in humans.

Objective— Endothelin (ET)-1 plays a role in vascular reactive oxygen species production and inflammation. ET-1 has been implicated in human atherosclerosis and abdominal aortic aneurysm (AAA) development. ET-1 overexpression exacerbates high-fat diet–induced atherosclerosis in apolipoprotein E −/− ( Apoe −/− ) mice. ET-1–induced reactive oxygen species and inflammation may contribute to atherosclerosis progression and AAA development. Approach and Results— Eight-week-old male wild-type mice, transgenic mice overexpressing ET-1 selectively in endothelium (eET-1), Apoe −/− mice, and eET-1/ Apoe −/− mice were fed high-fat diet for 8 weeks. eET-1/ Apoe −/− had a 45% reduction in plasma high-density lipoprotein ( P <0.05) and presented ≥2-fold more aortic atherosclerotic lesions compared with Apoe −/− ( P <0.01). AAAs were detected only in eET-1/ Apoe −/− (8/21; P <0.05). Reactive oxygen species production was increased ≥2-fold in perivascular fat, media, or atherosclerotic lesions in the ascending aorta and AAAs of eET-1/ Apoe −/− compared with Apoe −/− ( P <0.05). Monocyte/macrophage infiltration was enhanced ≥2.5-fold in perivascular fat of ascending aorta and AAAs in eET-1/ Apoe −/− compared with Apoe −/− ( P <0.05). CD4 + T cells were detected almost exclusively in perivascular fat (3/6) and atherosclerotic lesions (5/6) in ascending aorta of eET-1/ Apoe −/− ( P <0.05). The percentage of spleen proinflammatory Ly-6C hi monocytes was enhanced 26% by ET-1 overexpression in Apoe −/− ( P <0.05), and matrix metalloproteinase-2 was increased 2-fold in plaques of eET-1/ Apoe −/− ( P <0.05) compared with Apoe −/− . Conclusions— ET-1 plays a role in progression of atherosclerosis and AAA formation by decreasing high-density lipoprotein, and increasing oxidative stress, inflammatory cell infiltration, and matrix metalloproteinase-2 in perivascular fat, vascular wall, and atherosclerotic lesions.

Mmp2 knockout impaired Ang II-induced vascular injury but not BP elevation. BM transplantation revealed a role for immune cells in Ang II-induced BP elevation, and for both vascular and immune cell MMP2 in Ang II-induced endothelial dysfunction.

FOXP3+ Treg deficiency exaggerates Ang II-induced microvascular injury by modulating innate and adaptive immune responses.

Endothelium-derived endothelin (ET)-1 has been implicated in the development of hypertension and end-organ damage, but its exact role remains unclear. We have shown that tamoxifen-inducible endothelium-restricted human ET-1 overexpressing (ieET-1) mice exhibited blood pressure rise after a 3-week induction in an ET type A (ET) receptor-dependent manner, in absence of vascular and renal injury. It is unknown whether long-term ET-1 overexpression results in sustained blood pressure elevation and vascular and renal injury. Adult male ieET-1 and control tamoxifen-inducible endothelium-restricted Cre recombinase (ieCre) mice were induced with tamoxifen and 2.5 months later, were treated with or without the ET receptor blocker atrasentan for 2 weeks. Three-month induction of endothelial human ET-1 overexpression increased blood pressure (<0.01), reduced renal artery flow (<0.001), and caused mesenteric small artery stiffening (<0.05) and endothelial dysfunction (<0.01). These changes were accompanied by enhanced mesenteric small artery and expression, and perivascular adipose tissue oxidative stress (<0.05) and monocyte/macrophage infiltration (<0.05). Early renal injury was demonstrated by increased kidney injury molecule-1 expression in renal cortex tubules (<0.05), with, however, undetectable lesions using histochemistry staining and unchanged urinary albumin. There was associated increased myeloid (CD11b) and myeloid-derived suppressive cell (CD11bGr-1) renal infiltration (<0.01) and greater frequency of myeloid and renal cells expressing the proinflammatory marker CD36 (<0.05). Atrasentan reversed or reduced all of the above changes (<0.05) except the endothelial dysfunction and collagen expression and reduced renal artery flow. These results demonstrate that long-term exposure to endothelial human ET-1 overexpression causes sustained blood pressure elevation and vascular and renal injury via ET receptors.

We investigated the role of angiotensin type 1a receptors (AGTR1a) in vascular injury induced by aldosterone activation of mineralocorticoid receptors (MR) in Agtr1a−/− and wild-type mice infused with aldosterone for 14 days while receiving 1% NaCl in drinking water. Aldosterone increased systolic blood pressure by ~30 mmHg in wild-type mice, and ~50 mmHg in Agtr1a−/− mice. Aldosterone induced aortic and small artery remodeling and impaired endothelium-dependent relaxation in wild-type mice, and enhanced fibronectin and collagen deposition, and vascular inflammation. None of these vascular effects were observed in Agtr1a−/− mice. Aldosterone effects were prevented by the AGTR1 antagonist losartan in wild-type mice. In contrast to aldosterone, norepinephrine caused similar BP increase and mesenteric artery remodeling in wild-type and Agtr1a−/− mice. Agtr1a−/− mice infused with aldosterone did not increase sodium excretion in response to a sodium chloride challenge, suggesting sodium retention that could contribute to the exaggerated blood pressure rise induced by aldosterone. Agtr1a−/− mice had decreased mesenteric artery expression of the calcium-activated potassium channel Kcnmb1, which may enhance myogenic tone and together with sodium retention exacerbate BP responses to aldosterone/salt in Agtr1a−/− mice. We conclude that although aldosterone activation of MR raises BP more in Agtr1a−/− mice, AGTR1a is required for MR stimulation to induce vascular remodeling and inflammation, and endothelial dysfunction.