The activated renin-angiotensin-aldosterone system increases blood pressure and intracellular signals, thus leading to cardiac fibrosis. Whether increased blood pressure or angiotensin II-activated signaling is responsible for elevated angiotensin II-induced cardiac remodeling is unknown. Here, we aimed to determine whether lowering blood pressure with hydralazine might prevent inflammation and cardiac fibrosis in response to angiotensin II. We used the C57/BL6 mouse model of angiotensin II infusion (1,500 ng/kg per minute) for 7 days; 40 male mice (6 weeks old) were randomly assigned to 4 groups for treatment: mice with angiotensin II or vehicle infusion were given hydralazine in drinking water (250 mg/l per day). Heart sections were stained with hematoxylin and eosin and Masson trichrome and examined by immunohistostaining. The levels of proinflammatory cytokines were measured by real-time PCR and western blot analysis. The blood pressure of the control group began to increase on day 4 of angiotensin II infusion, and hydralazine treatment prevented angiotensin II-induced hypertension. Compared with the control, hydralazine treatment to lower blood pressure blocked angiotensin II-induced fibrosis and reduced Mac-2(+) inflammatory cell infiltration and proinflammatory cytokine expression. The accumulation of blood-borne CD45(+) cells and α-smooth muscle actin-positive myofibroblasts was also significantly reduced. Our results indicate that elevated blood pressure is essential for inflammatory cell infiltration and myofibroblast formation, which contribute to angiotensin II infusion-induced cardiac fibrosis. Hydralazine treatment attenuates cardiac fibrosis in response to angiotensin II. Lowering pressure could be an effective therapeutic target for cardiac fibrosis.

BackgroundDiabetic patients, through incompletely understood mechanisms, endure exacerbated ischemic heart injury compared to non-diabetic patients. Intermedin (IMD) is a novel calcitonin gene-related peptide (CGRP) superfamily member with established cardiovascular protective effects. However, whether IMD protects against diabetic myocardial ischemia/reperfusion (MI/R) injury is unknown.MethodsDiabetes was induced by streptozotocin in Sprague–Dawley rats. Animals were subjected to MI via left circumflex artery ligation for 30 minutes followed by 2 hours R. IMD was administered formally 10 minutes before R. Outcome measures included left ventricular function, oxidative stress, cellular death, infarct size, and inflammation.ResultsIMD levels were significantly decreased in diabetic rats compared to control animals. After MI/R, diabetic rats manifested elevated intermedin levels, both in plasma (64.95 ± 4.84 pmol/L, p < 0.05) and myocardial tissue (9.8 ± 0.60 pmol/L, p < 0.01) compared to pre-MI control values (43.62 ± 3.47 pmol/L and 4.4 ± 0.41). IMD administration to diabetic rats subjected to MI/R decreased oxidative stress product generation, apoptosis, infarct size, and inflammatory cytokine release (p < 0.05 or p < 0.01).ConclusionsBy reducing oxidative stress, inflammation, and apoptosis, IMD may represent a promising novel therapeutic target mitigating diabetic ischemic heart injury.

The protective effects of gAd during I/R are mediated, at least in part, by modulating SERCA activity and consequently suppressing ER stress via the activation of PI3K/Akt signaling.

Background/Aims: Atherosclerosis is a chronic inflammatory disease. Intracellular adhesion molecule-1 (ICAM-1), vascular cellular adhesion molecule-1 (VCAM-1), and monocyte chemoattractant protein-1 (MCP-1) play important roles in inflammatory processes. P38 mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-κB signaling regulate ICAM-1, VCAM-1, and MCP-1 expression. Angiotensin (Ang) II upregulates ICAM-1, VCAM-1, and MCP-1 expression through the P38 MAPK and NF-κB pathways. Ang-(1-7) may oppose the actions of Ang II. We investigated whether Ang-(1-7) prevents Ang II-induced ICAM-1, VCAM-1, and MCP-1 expression in human umbilical vein endothelial cells (HUVECs). Methods: ICAM-1, VCAM-1, and MCP-1 expression was estimated by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA); P38, NF-κB, and p-IκB-a expression was estimated by western blotting. Results: Ang-(1-7) inhibited Ang II-induced ICAM-1, VCAM-1, and MCP-1 expression and secretion in HUVECs. Ang II sharply increased P38 MAPK phosphorylation, which was inhibited by pretreatment with Ang-(1-7). Moreover, Ang-(1-7) significantly inhibited Ang II-induced IκB-a phosphorylation and NF-κB P65 nuclear translocation. The MAS receptor antagonist A-779 abolished the suppressive effects of Ang-(1-7). Conclusion: Ang-(1-7) attenuates Ang II-induced ICAM-1, VCAM-1, and MCP-1 expression via the MAs receptor by suppressing the P38 and NF-κB pathways in HUVECs. Ang-(1-7) might delay the progression of inflammatory diseases, including atherosclerosis.

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Background. Sirtuin 1 (SIRT1) is a member of the sirtuin family, which could activate cell survival machinery and has been shown to be protective in regulation of heart function. Here, we determined the mechanism by which SIRT1 regulates Angiotensin II- (AngII-) induced cardiac hypertrophy and injury in vivo and in vitro. Methods. We analyzed SIRT1 expression in the hearts of control and AngII-induced mouse hypertrophy. Female C57BL/6 mice were ovariectomized and pretreated with 17β-estradiol to measure SIRT1 expression. Protein synthesis, cardiomyocyte surface area analysis, qRT-PCR, TUNEL staining, and Western blot were performed on AngII-induced mouse heart hypertrophy samples and cultured neonatal rat ventricular myocytes (NRVMs) to investigate the function of SIRT1. Results. SIRT1 expression was slightly upregulated in AngII-induced mouse heart hypertrophy in vivo and in vitro, accompanied by elevated cardiomyocyte apoptosis. SIRT1 overexpression relieves AngII-induced cardiomyocyte hypertrophy and apoptosis. 17β-Estradiol was able to protect cardiomyocytes from AngII-induced injury with a profound upregulation of SIRT1 and activation of AMPK. Moreover, estrogen receptor inhibitor ICI 182,780 and SIRT1 inhibitor niacinamide could block SIRT1's protective effect. Conclusions. These results indicate that SIRT1 functions as an important regulator of estrogen-mediated cardiomyocyte protection during AngII-induced heart hypertrophy and injury.

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