Novel Insights into the Cardioprotective Effects of Calcitriol in Myocardial Infarction.

BACKGROUND: Increasing evidence indicates that vitamin D deficiency negatively affects the cardiovascular system. Here we studied the therapeutic effects of calcitriol in myocardial infarction (MI) and investigated its underlying mechanisms. METHODS: A MI model of Kun-ming mice induced by left anterior descending coronary artery ligation was utilized to study the potential therapeutic effects of calcitriol on MI. AC16 human cardiomyocyte-like cells treated with TNF-α were used for exploring the mechanisms that underlie the cardioprotective effects of calcitriol. RESULTS: We observed that calcitriol reversed adverse cardiovascular function and cardiac remodeling in post-MI mice. Mechanistically, calcitriol suppressed MI-induced cardiac inflammation, ameliorated cardiomyocyte death, and promoted cardiomyocyte proliferation. Specifically, calcitriol exerted these cellular effects by upregulating Vitamin D receptor (VDR). Increased VDR directly interacted with p65 and retained p65 in cytoplasm, thereby dampening NF-κB signaling and suppressing inflammation. Moreover, up-regulated VDR was translocated into nuclei where it directly bound to IL-10 gene promoters to activate IL-10 gene transcription, further inhibiting inflammation. CONCLUSION: We provide new insights into the cellular and molecular mechanisms underlying the cardioprotective effects of calcitriol, and we present comprehensive evidence to support the preventive and therapeutic effects of calcitriol on MI.

Xin-Ji-Er-Kang protects myocardial and renal injury in hypertensive heart failure in mice.

BACKGROUND: Xin-Ji-Er-Kang (XJEK) as a herbal formula of traditional Chinese medicine (TCM) has shown the protective effects on myocardial function as well as renal function in mouse models of myocardial infarction. HYPOTHESIS/PURPOSE: We investigated the effects of XJEK on cardiovascular- and renal-function in a heart failure mouse model induced by high salt (HS) and the associated mechanisms. STUDY DESIGN: For the purpose of assessing the effects of XJEK on a hypertensive heart failure model, mice were fed with 8% high salt diet. XJEK was administered by oral gavage for 8 weeks. Cardiovascular function parameters, renal function associated biomarkers and XJEK's impact on renin-angiotensin-aldosterone system (RAAS) activation were assessed. To determine the underlying mechanism, the calpain1/junctophilin-2 (JP2)/sarcoplasmic reticulum Ca2+ ATPase (SERCA2a) pathway was further studied in AC16 cells after angiotensin II-challenge or after calpastatin small interfering RNA (siRNA) transfection. RESULTS: Mice on HS-diet exhibited hypertensive heart failure along with progressive kidney injury. Similar to fosinopril, XJEK ameliorated hypertension, cardiovascular-and renal- dysfunction in mice of HS-diet group. XJEK inhibited HS-induced activation of RAAS and reversed the abnormal expression pattern of calpain1and JP2 protein in heart tissues. XJEK significantly improved cell viability of angiotensin II-challenged AC16 cells. Moreover, XJEK's impact on calpain1/JP2 pathway was partly diminished in AC16 cells transfected with calpastatin siRNA. CONCLUSION: XJEK was found to exert cardiovascular- and renal protection in HS-diet induced heart failure mouse model. XJEK inhibited HS-diet induced RAAS activation by inhibiting the activity and expression of calpain1 and protected the junctional membrane complex (JMC) in cardiomyocytes.

Xin-Ji-Er-Kang ameliorates kidney injury following myocardial infarction by inhibiting oxidative stress via Nrf2/HO-1 pathway in rats.

AIM: Cardiovascular diseases, such as coronary heart disease and myocardial infarction (MI) are currently considered as the leading causes of death and disability. The aim of the present study is to investigate the effects of Xin-Ji-Er-Kang (XJEK) on kidney injury and renal oxidative stress. In addition, the associated mechanism involved in these processes was examined in an MI model, and particularly focused on the nuclear factor erythroid 2-related factor (NRF2)/heme oxygenase-1 (HO-1) pathway. MATERIALS AND METHODS: A total of 138 Sprague-Dawley rats were used in the present study. The control group was designated as 0 wk (n = 8). A total of 3 phases (2, 4, 6 wk) of administration were used in the sham-operated groups (sham, n = 10), MI groups (MI, n = 10), MI + XJEK groups (XJEK, n = 10) and MI + fosinopril groups (fosinopril, n = 10). Additional 10 rats were used to evaluate the infarct area. At 2, 4 or 6 wk post-MI, the hemodynamic parameters were monitored, the rats were sacrificed, then blood, heart and renal tissues were collected for furtherly analysis. RESULTS: The results indicated that XJEK administration continuously ameliorated renal hypertrophy index, blood urea nitrogen and cystatin C concentrations. XJEK further improved post-MI cardiac function by limiting scar formation and caused a downregulation in the hemodynamic parameters at the end of 2 and 4 wk. The hemodynamic parameters were upregulated after 6 wk treatment with XJEKcompared with those noted in the MI groups. Similarly, XJEK treatment for 2 wk potentiated Nrf2 nuclear translocation and HO-1 expression and inhibited the deficiency of nuclear Nrf2 and HO-1 at 6 wk post-MI compared with that of the MI groups, indicating the attenuation of the renal oxidative stress condition. The levels of malondialdehyde and angiotensin II (Ang II) in plasma and renal tissues, as well as the levels of aldosterone, 8-hydroxydeoxyguanosine, angiotensin II type 1 receptor and NADPH Oxidase-4 in the kidney tissue significantly decreased following XJEK treatment for 6 wk. In addition, the XJEK treatment groups revealed a significant upregulation in the activity of superoxide dismutase and in the total antioxidant capacity activity compared with those noted in the corresponding MI groups. CONCLUSION: These results demonstrated that progressive nephropathy in MI rats was associated with intrarenal activation of the renin-angiotensin-aldosterone system. Concomitantly, this process was associated with oxidative stress and impaired Nrf2 activation. The improvement in the severity of nephropathy by XJEK in this model may be associated with the reversal of these abnormalities.

Protective effect of Xin-Ji-Er-Kang on cardiovascular remodeling in high-salt induced hypertensive mice: Role ofoxidative stress and endothelial dysfunction.

BACKGROUND: Xin-Ji-Er-Kang (XJEK) is a Chinese herbal formula that has beenreported to exert effective protection against cardiovascular diseases, such as hypertension and myocarditis. OBJECTIVE: The aim of the present study was to investigate the effect of XJEK on high-salt-induced hypertensive mice and its possible mechanism. METHODS: The model of hypertension was established through a high-salt diet. Sixty male Kunming mice were randomized into six groups, namely the Control, Model, Low-dose XJEK, Middle-dose XJEK, High-dose XJEK and Fosinopril groups (n=10 per group). Different steady interventions were given to each group: 0.9% Sodium chloride was added to the diet of the Control group and 8% sodium chloride to the diet of the other five groups from the very beginning. An additional 4, 8 and 12 g/kg/day XJEK were intragastrically administered to the Low-dose, Middle-dose and High-dose XJEK groups, respectively, and 2 mg/kg/day fosinopril to the fosinopril group, from the start of week 5. Systolic blood pressure (SBP) was measured weekly from weeks 1 to 8 using the tail-cuff method. At the end of week 8, left ventricular (LV) systolic pressure, LV end-diastolic pressure and rate of rise of LV pressure were examined using a TransonicScisense catheter (Transonic Systems Inc,Ithaca, NY,USA). Endothelium-dependent relaxations induced by acetylcholine were observed in an isolated thoracic aorta ring. Serum and heartsweresampled for the measurement of the following indexes:Serum nitric oxide (NO), superoxide dismutase (SOD) activity and malondialdehyde (MDA) content (determined by colorimetricanalysis); serum angiotensin II(Ang II), endothelin-1, endothelial NO synthase (eNOS), asymmetric dimethylarginine (ADMA), tetrahydrobiopterin (BH4) concentration and l-arginine (determined by enzyme-linked immunosorbent assay); heart to body weight (HW/BW) ratio; myocardial morphological change (determined by HE and VG staining); myocardial eNOS expression (determined by immunofluorescence), and myocardial endothelin receptor A (ETA) expression (determined by western blotting). RESULTS: Statistical data showed that the HW/BW ratio was significantly decreased in the drug treatment group. XJEK treatment could improve the heart systolic and diastolic function and ameliorate hemodynamic parameters and vascular remodeling indexes. Colorimetric results showed that, compared with the model group, XJEK increased serum SOD, NOlevels, and decreased those of serum MDA and Ang II. XJEK reverted changes in cardiac pathology, decreased the myocardial cross-sectional area, collagen volume fraction and perivascular collagen area and improved endothelial dysfunction (ED) by promoting eNOS activity, enhancing NO bioavailability, increasing the expression of BH4 and decreasing ETA content. In addition, treatment with XJEK decreased ADMA content in the myocardium. CONCLUSION: In conclusion, XJEK mitigates cardiac remodeling in high-salt-induced hypertensive mice. The potential mechanism involves improved oxidative stress and endothelial dysfunction, independently of ameliorating BP.