Angiotensin II (ANG II) promotes vascular inflammation through nuclear factor-kappaB (NF-kappaB)-mediated induction of pro-inflammatory genes. The role of peroxisome proliferator-activated receptors (PPARs) in modulating vascular inflammation and atherosclerosis in vivo is unclear. The aim of the present study was to examine the effects of ANG II on PPARs and NF-kappaB-dependent pro-inflammatory genes in the vascular wall in an in vivo model of atherosclerosis and aneurysm formation. Six-month-old male apolipoprotein E-deficient (apoE-KO) mice were treated with ANG II (1.44 mg/kg per day for 30 days). ANG II enhanced vascular inflammation, accelerated atherosclerosis, and induced formation of abdominal aortic aneurysms. These effects of ANG II in the aorta were associated with downregulation of both PPAR-alpha and PPAR-gamma mRNA and protein and an increase in transcription of monocyte chemotactic protein-1 (MCP-1), macrophage-colony stimulating factor (M-CSF), endothelial-selectin (E-selectin), intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) throughout the entire aorta. ANG II also activated NF-kappaB with increases in both p52 and p65 NF-kappaB subunits. In summary, these in vivo results indicate that ANG II, through activation of NF-kappaB-mediated pro-inflammatory genes, promotes vascular inflammation, leading to acceleration of atherosclerosis and induction of aneurysm in apoE-KO mice. Downregulation of PPAR-alpha and -gamma by ANG II may diminish the anti-inflammatory potential of PPARs, thus contributing to enhanced vascular inflammation.

Apolipoprotein E-knockout (ApoE-KO) mice develop advanced atherosclerotic lesions by 1 yr of age and have been well characterized pathologically and morphologically, but little is known regarding their cardiovascular physiology and hemodynamics. We used noninvasive Doppler ultrasound to measure aortic and mitral blood velocity and aortic pulse-wave velocity in 13-mo-old ApoE-KO and wild-type (WT) mice anesthetized with isoflurane. In other mice from the same colony, we measured systolic blood pressure, body weight, heart weight, cholesterol, and hematocrit. Heart rate and blood pressure were comparable (P = not significant) between ApoE-KO and WT mice, but significant decreases (P < 0.001) were found in body weight (-22%) and hematocrit (-11%), and significant increases were found in heart weight (+23%), aortic velocity (+60%), mitral velocity (+81%) (all P < 0.001), and pulse-wave velocity (+13%, P < 0.05). We also found inflections in the aortic arch velocity signal consistent with enhanced peripheral wave reflection. Thus ApoE-KO mice have phenotypic alterations in indexes of peripheral vascular resistance and compliance and significantly elevated cardiac outflow velocities and heart weight-to-body weight ratios.

Objectives-Angiotensin II (Ang II) promotes vascular inflammation, accelerates atherosclerosis, and induces abdominal aortic aneurysm (AAA). These changes were associated with activation of nuclear factor (NF)-B-mediated induction of proinflammatory genes. The incidence of AAA in this model was higher in male than in female mice, and the vascular effects of estrogen may be associated with anti-inflammatory actions. The present study was undertaken to test the hypothesis that estrogen can attenuate Ang II-induced AAA in apolipoprotein E-deficient mice via its antiinflammatory mechanism. Methods and Results-Infusion of Ang II (1.44 mg/kg per d for 1 month) induced AAA in 90% of the animals (nϭ20) with an expansion of the suprarenal aorta (diameter 1.9Ϯ0.14 mm versus Ͻ1 mm in normal mice). In mice treated with 17␤-estradiol (E2, 0.25-mg subcutaneous pellets), Ang II induced AAA only in 42% of the animals (nϭ19) with a significant reduction of average diameters of the suprarenal aorta (1.5Ϯ0.14 mm). E2 also decreased the expressions of intracellular adhesion molecule-1, vascular cellular adhesion molecule-1, E-selectin, monocyte chemotactic protein-1, and macrophage-colony stimulating factor in the aorta. Key Words: estrogen Ⅲ aneurysm Ⅲ vascular inflammation Ⅲ PPAR Ⅲ gene expression A therosclerosis is an inflammatory disease. 1 Infiltration of monocytes and macrophages into the vessel wall is a major source of proteolytic enzymes, including metalloproteinases, which degrade extracellular matrix, thus impairing the integrity of the artery wall and causing aneurysm. 2 Angiotensin II (Ang II) has been implicated in vascular inflammation and progression of atherosclerosis. 3,4 Chronic infusion of Ang II in apolipoprotein E-deficient (apoE-KO) mice induces aneurysm. 5 We demonstrated that vascular inflammation and aneurysm induced by Ang II were associated with activation of nuclear transcription factor (NF)-Bmediated proinflammatory gene induction. 6,7 It has been reported clinically that the incidence of abdominal aortic aneurysm (AAA) was higher in males than in females. 8 Ang II-induced AAA was also higher in male than in female mice in this model. 9 Estrogen has long been recognized to have vascular actions. 10 Treatment with estrogen reduces atherosclerotic lesion formation in several animal models, including apoE-KO mice, 11,12 even in the absence of lipid-lowering effects. 13 Accumulating evidence suggests that the antiatherosclerotic effects of estrogen can be attributed, at least in part, to anti-inflammatory actions. 14,15 Furthermore, there is in vivo evidence that estrogen inhibits the NF-B pathway, which contributes to anti-inflammatory actions. 16 The present study, therefore, was aimed to test the hypothesis that treatment of 17␤-estradiol can attenuate Ang IIinduced AAA in apoE-KO mice via the mechanism of inhibiting NF-B-mediated proinflammatory gene induction. Conclusions-These MethodsMale apoE-KO mice (Jackson Laboratory, Bar Harbor, Maine) were fed normal rodent chow. When the mice were 5 months ol...

Background-Endothelial NO deficiency (endothelial NO synthase [eNOS]-knockout [KO]) enhanced smooth musclecell (SMC)-rich neointimal lesion formation in a mouse model of carotid artery ligation (CAL). Recent evidence indicated that stromal cell-derived factor-1␣ (SDF-1␣)-mediated recruitment of circulating SMC progenitor cells substantially contributed to the SMC-rich neointimal hyperplasia induced by vascular injury. The goal of this study was to investigate the effects of eNOS deficiency on the expression of SDF-1␣ and mobilization of circulating SMC progenitor cells in CAL model. Methods and Results-Two-to 3-month-old C57BL/6J wild-type (WT) and eNOS-KO mice were evaluated 1, 2, or 4 weeks after CAL. CAL-induced expression of SDF-1␣, as detected by immunohistochemical staining and further quantified by ELISA in the ligated carotid arteries, was moderate and transient with a peak at 1 week in WT mice. SDF-1␣ expression was significantly higher at 1 week and persisted through 2 weeks in eNOS-KO mice. CAL was associated with increased circulating stem cell antigen-1ϩ (Sca-1 ϩ )/c-Kit Ϫ /Lin Ϫ cells (interpreted as SMC progenitor cells), which peaked at 1 week in WT mice. This effect was also significantly greater and longer-lasting in eNOS-KO than WT mice. The number of circulating Sca-1 ϩ /c-Kit Ϫ /Lin Ϫ cells was positively correlated with the expression of SDF-1␣ but not vascular endothelial growth factor in the ligated carotid arteries. Furthermore, immunostaining showed abundant Sca-1-positive cells in the adventitia of the 1-week ligated carotid arteries from eNOS-KO mice but not in WT mice. We also determined that eNOS deficiency enhanced CAL-induced intimal cell proliferation in the ligated arteries as detected by proliferating cell nuclear antigen staining but did not induce cell apoptosis as detected by staining for active caspase-3. Conclusion-Our results indicate that eNOS deficiency exacerbates CAL-induced expression of SDF-1␣ and its receptorCXCR4. This is correlated with an increase in Sca-1 ϩ cells in peripheral blood and adventitia, which may contribute to vascular remodeling and SMC-rich neointimal lesion formation. This suggests that constitutive eNOS inhibits SDF-1␣ expression and provides an important vasculoprotective mechanism for intact endothelium to limit SMC proliferation and recruitment in response to vascular injury. Key Words: eNOS knockout mice Ⅲ neointima Ⅲ smooth muscle cell Ⅲ progenitor cell Ⅲ stromal cell-derived factor-1␣ S mooth muscle cell (SMC) accumulation forming a neointima is a hallmark of many vascular diseases, such as atherosclerosis, 1 restenosis after angioplasty, 2 transplant vasculopathy, 3 and vein bypass graft failure. 4 Recent studies examining SMC origin have garnered much attention in defining new therapeutic approaches and strategies. Four potential sources of SMCs include migration of medial SMCs, 5 proliferation of pre-existing intimal clones, 6 emigration of adventitial fibroblasts, 7,8 and infiltration of circulating progenitor cells. 9,10 Among these, ...

Cardiovascular diseases, such as atherosclerosis and hypertension, are associated with arterial stiffening. Previous studies showed that ANG II exacerbated atherosclerosis and induced hypertension and aneurysm formation in apolipoprotein E-deficient (apoE-KO) mice. The aim of the present study was to examine the effects of chronic treatment of ANG II on the arterial elastic properties in apoE-KO mice. We hypothesized that ANG II will injure the arterial wall resulting in increased arterial stiffening. Male apoE-KO mice were infused with either ANG II (1.44 mg ⅐ kg Ϫ1 ⅐ day Ϫ1 ) or vehicle (PBS) for 30 days. ANG II treatment accelerated atherosclerosis in the carotid artery by sixfold (P Ͻ 0.001) and increased blood pressure by 30% (P Ͻ 0.05). Additionally, our data demonstrated that ANG II increased arterial stiffening using both in vivo and in vitro methods. ANG II significantly increased pulse wave velocity by 36% (P Ͻ 0.01) and decreased arterial elasticity as demonstrated by a more than 900% increase in maximal stiffening (high strain Young's modulus) compared with vehicle (P Ͻ 0.05). These functional changes were correlated with morphological and biochemical changes as demonstrated by an increase in collagen content (60%), a decrease in elastin content (74%), and breaks in the internal elastic lamina in the aortic wall. In addition, endotheliumindependent vasorelaxation to sodium nitroprusside was impaired in the aortic rings of ANG II-treated mice compared with vehicle. Thus, the present data indicate that ANG II injures the artery wall in multiple ways and arterial stiffening may be a common outcome of ANG II-induced arterial damage.aneurysm; atherosclerosis; hypertension; vascular stiffness LARGE ARTERIES ARE CHARACTERIZED by their elastic properties and ability to synthesize many vasoactive substances. These properties enable the arterial wall to function as a modulator of blood pressure and more generally of cardiovascular hemodynamics (14). It is well recognized that the mechanical properties of large arteries are primarily determined by the composition of the arterial wall. The "passive" biomechanical properties of the arterial wall are influenced predominantly by the extracellular matrix proteins, collagen, and elastin, whereas the "active" properties depend on the activation of vascular smooth muscle cells. Aging, environmental and genetic factors are responsible for the functional (decreased release of vasodilators and increased synthesis of vasoconstrictors) and structural (smooth muscle cell hypertrophy, extracellular matrix accumulation, and degradation of elastin) (19) modifications of the arterial wall and the arterial endothelium. These modifications could lead to a diminution of elasticity and increased vascular stiffness.Atherosclerosis produces many pathological changes in the arterial wall, one of the most important being a progressive increase in arterial stiffening. It has also been demonstrated that hypertension can increase aortic stiffness (3,4,23,24,26,28,37). In addition, previous...