Search

It has been shown that the inflammatory cytokine tumor necrosis factor α (TNFα) plays a role in the development of hypertension and end-stage renal diseases. We hypothesize that TNFα contributes to endothelial dysfunction and cardiac and vascular injury in deoxycorticosterone acetate (DOCA)/salt-hypertensive mice. The wild-type or TNFα-deficient mice were uninephrectomized and implanted with DOCA pellet treatment for 5 weeks; the mice were given either tap water or 1% NaCl drinking water. DOCA mice developed hypertension (systolic blood pressure (SBP): 167±5 vs. 110±4 mmHg in control group, p<0.05), cardiac and vascular hypertrophy, and the impairment of endothelium-dependent relaxation to acetylcholine (EDR). TNFα deficiency improved EDR and lowered cardiac and vascular hypertrophy with a mild reduction in SBP (152±4 vs. 167±5 mmHg in DOCA group, p<0.05) in DOCA mice. The mRNA expressions of the inflammatory cytokines, including TNFα, interleukin 1β (IL1β), monocyte chemotactic protein 1 (MCP1), and monocyte/macrophage marker F4/80 were significantly increased in the aorta of DOCA-hypertensive mice; TNFα deficiency reduced these inflammatory gene expressions. DOCA-hypertensive mice also exhibited an increase in the vascular oxidative fluorescence intensities, the protein expressions of gp91phox and p22phox, and the fibrotic factors transforming growth factor β and fibronectin. TNFα deficiency reduced oxidative stress and fibrotic protein expressions. The DOCA mice also showed a decrease in the protein expression of eNOS associated with increased miR155 expression; TNFα deficiency prevented a decrease in eNOS expression and an increase in miR155 expression in DOCA mice. These results support the idea that TNFα significantly contributes to vascular inflammation, vascular dysfunction, and injury in hypertension.

Objective: Hypertension is associated with a low-grade systemic inflammation in cardiovascular system. Macrophage infiltration may initiate an inflammatory process that contributes to vascular and ventricular remodeling in hypertensive human and mice. The present study investigated the effect of chemical depletion of macrophage using liposome encapsulated clodronate (LEC) on cardiac hypertrophy and remodeling in angiotensin (Ang) II hypertensive mice.Methods: C57BL/6 mice received an Ang II (1.1 mg/kg/day with a minipump) infusion for 2 weeks to induce hypertension. Endothelium-dependent relaxation (ED) was examined by organ bath, hematoxylin and staining and Masson-Trichrome staining were used to evaluate aorta and cardiac hypertrophy and fibrosis.Results: Ang II infusion significantly increased systolic blood pressure (SBP), cardiac hypertrophy and fibrosis, and impaired EDR accompanied by increased macrophage infiltration in the heart. Treatment with LEC significantly lowered Ang II-induced cardiac hypertrophy and fibrosis and cardiac macrophage infiltration, and improved EDR with a mild reduction in SBP. Ang II increased the expression of inflammatory cytokines tumor necross factor alpha and interleukin 1 beta and profibrotic factors transforming growth factor beta 1 and fibronectin in the heart, with was reduced by LEC treatment. Treatment with LEC prevented Ang II-induced the phosphorphorylation of ERK1/2 and c-Jun-N-terminal kinase.Conclusions: Our study suggests that cardiac macrophage may be critical for hypertensive cardiac hypertrophy and remodeling, the underlying mechanisms may involve initial heart inflammation and the activation of hypertrophic MAPKs pathway.

Puerarin, a major isoflavonoid compound from Chinese herb Kudzu roots, has been widely used for the treatment of hypertensive and cardiovascular diseases in China. Here, we investigated puerarin's beneficial effects on the cardiovascular system in angiotensin (Ang) II-induced hypertensive rats. Sprague-Dawley rats were treated with Ang II for 5 days or with puerarin for 10 days followed by Ang II and puerarin for 5 days. Endothelium-dependent relaxation (EDR) to acetylcholine was determined using an organ chamber bath. Ang II increased the systolic blood pressure (SBP: 178 ± 5 mmHg vs. 112 ± 3 mmHg in control, p < 0.05), aortic (30%, p < 0.05), and left ventricular (LV) weight (23%); puerarin reduced SBP (160 ± 2 mmHg, p < 0.05), aortic, and left ventricular weight in Ang II-infused rats. Puerarin also reduced aortic medial thickness and myocardial cell surface area in Ang II-infused rats. Compared with control rats, Ang II infused rats exhibited an impaired EDR with reduction in the protein expression of phosphor-eNOS at Ser 1177 and an increase in the expression of gp91phox (85%), p22phox (113%), transforming growth factor β1 (145%) and vascular cell adhesion molecule 1 (82%). Puerarin improved EDR and reversed the changes in Ang II-induced protein expression of above molecules. Our results demonstrate that in Ang II-induced hypertensive rats, puerarin protects against endothelial dysfunction and end organ damage with a mild reduction in SBP, and that the cardiovascular beneficial effects of puerarin may be in part attributed to its anti-oxidant and upregulation of phosphor-eNOS.

Puerarin is an isoflavonoid isolated from the Chinese herb, Kudzu roots (also known as Gegen), which has been widely used for the treatment of hypertensive diseases and diabetic mellitus in traditional Chinese medicine. Dahl salt-sensitive (DS) rat is a genetic model of salt-sensitive hypertension with cardiovascular injury and vascular insulin resistance. Here, we investigated whether puerarin improved vascular insulin resistance and attenuated cardiac and aortic remodeling in salt-sensitive hypertension. DS rats were given a normal (NS) or high salt diet (HS) for five weeks. An additional group of DS rats was pretreated with puerarin and NS for 10 days, then switched to HS plus puerarin for five weeks. HS for five weeks increased systolic blood pressure (SBP), cardiac hypertrophy and fibrosis, and aortic hypertrophy with increased the expression of phosphor-ERK1/2 in the aorta and heart; puerarin attenuated cardiac and aortic hypertrophy, cardiac fibrosis and phosphor-ERK1/2 with a mild reduction in SBP. Hypertensive rats also manifested impairment of acetylcholine- and insulin-mediated vasorelaxation and insulin-mediated Akt and eNOS phosphorylation associated with the activation of NF[Formula: see text]B/TNF[Formula: see text]/JNK pathway. Puerarin improved acetylcholine- and insulin-mediated vasorelaxation and insulin-stimulated Akt/NO signaling with the inhibition of the NF[Formula: see text]B inflammatory pathway. Our results demonstrated that in salt-sensitive hypertension, puerarin improved vascular insulin action with cardiovascular beneficial effects. Our results found that the underlying mechanisms may involve its inhibition of NF[Formula: see text]B/JNK and ERK1/2 pathway. These results suggest that puerarin could be used as a new antihypertensive agent to expand our armamentarium for the prevention and treatment of end-organ damage in individuals with hypertension and metabolic diseases.

Obesity and cigarette smoke are major cardiovascular (CV) risk factors and, when coexisting in the same individuals, have additive/synergistic effects upon CVD. We studied the mechanisms involved in nicotine enhancement of CVD in Sprague Dawley rats with diet-induced obesity. The rats were fed either a high fat (HFD) or normal rat chow diet with or without nicotine (100 mg/L in drinking water) for 20 weeks. HFD rats developed central obesity, increased systolic blood pressure (SBP), aortic superoxide (O2-) production, and impaired endothelial nitric oxide synthase (eNOS) and endothelium-dependent relaxation to acetylcholine (EDR). Nicotine further increased SBP, O2- and impaired eNOS and EDR in obese rats. In the peritoneal macrophages from obese rats, tumor necrosis factor (TNF) α, interleukin 1β and CD36 were increased, and were further increased in nicotine-treated obese rats. Using PCR array we found that 3 of 84 target proinflammatory genes were increased by 2-4 fold in the aorta of obese rats, 11 of the target genes were further increased in nicotine-treated obese rats. HUVECs, incubated with conditioned medium from the peritoneal macrophages of nicotine treated-obese rats, exhibited reduced eNOS and increased NADPH oxidase subunits gp91phox and p22phox expression. Those effects were partially prevented by adding anti-TNFα antibody to the conditioned medium. Our results suggest that nicotine aggravates the CV effects of diet-induced obesity including the oxidative stress, vascular inflammation and endothelial dysfunction. The underlying mechanisms may involve in targeting endothelium by enhancement of macrophage-derived TNFα.