[Effects of aerobic interval training on myocardial oxidative stress and inflammation in rats with myocardial infarction and its mechanism].

Objective: The present study was to determine the effects of aerobic interval training (AIT) on the expressions of SIRT1, Nox4 and inflammatory factor in the heart of rats with myocardial infarction (MI). Methods: Male Sprague Dawley rats were randomly divided into sham-operated group (C), sedentary MI group (MI) and MI with AIT group (ME) (n=10). The MI model was established by ligation the left anterior descending coronary artery. Rats in C groups were subjected to the same surgery, but only threaded and not ligated. After surgery 1 week, rats in ME groups took adaptability training for 1 week, and then subjected to 4 weeks treadmill exercise training. After training, the hearts were collected for histological observation. The level of malondialdehyde (MDA) and the activity of superoxide dismutase (SOD) in heart was assessed by ultraviolet spectrophotometry. The activity of lactate dehydrogenase (LDH) was determined by enzyme linked immunosorbent assay. The expression of sirtuin1 (SIRT1) mRNA was examined by real-time quantitative polymerase chain reaction (RT-qPCR). The protein expressions of SIRT1, NADPH oxidase 4 (Nox4), tumor necrosis factor-alpha (TNF-α) and interleukin-1ß (IL-1ß) were detected by Western blotting. The levels of reactive oxygen species (ROS) were detected by dihydroethidium (DHE) staining. Results: Compared with the C group, the expression level of cardiac Nox4 protein was increased (P＜0.01), the level of MDA, activity of LDH and the level of ROS were increased significantly (P＜0.01), and the expressions of TNF-α and IL-1ß protein were augmented in the heart of rats with MI (P＜0.01). However, the expressions of SIRT1 mRNA and protein and the activity of SOD were obviously decreased in MI group (P＜0.01). Furthermore, compared with the MI group, AIT increased the expressions of SIRT1 mRNA and protein and the activity of SOD in the heart of ME group (P＜0.01); Meanwhile, the expressions of cardiac Nox4, MDA level, LDH activity and ROS level were diminished in ME group (P＜0.01) as well as the decreased expressions of TNF-α and IL-1ß protein (P＜0.01). SIRT1 expression was negatively related to the expressions of NOX4 and ROS. Conclusion: AIT obviously inhibited myocardial oxidative stress and inflammatory reaction, improved cardiac function in rats with MI, and the mechanism was closely related to the activation of SIRT1-Nox4-ROS signaling pathway.

[Effect of aerobic interval training on the expression of renal CD40 in a rat model with myocardial infarction and its mechanism].

OBJECTIVE: To study the effects of aerobic interval training (AIT) on renal cluster of differentiation 40 (CD40) expression in rats with myocardial infarction (MI) and its possible mechanism. METHODS: Thirty-six rats were randomly divided into three groups (n=12):Sham, MI and MI with AIT (ME) groups. The MI model was established by ligation of the left anterior descending coronary artery. Treadmill training was performed five times a week for 8 weeks (AIT:60 min/day with 10 min of warm-up at 10 m/min and 50 min of exercise at 25 m/min 7 min interspersed with 3 min at 15 m/min). After training, cardiaorenal function and renal tissue remodeling were evaluated. The changes of CD40, high-sensitivity C reactive protein(hs-CRP), TNF-α, IL-6, p-NF-κBp65, blood urea nitrogen (BUN) and serum creatinine (sCr) were determined. RESULTS: Compared with the sham group, MI significantly increased left ventricular end-diastolic pressure (LVEDP) and decreased left ventricular systolic pressure (LVSP) and left indoor pressure change rate peak (dp/dtmax) in the MI group, concomitant with the increase in renal collagen volume fraction (CVF), which was reversed by AIT in the ME group. Moreover, compared with the sham group, CD40 was largely dispersed within the cytoplasm of renal tubule cells in the MI group. Meanwhile, the expressions of renal CD40 mRNA and protein, the levels of serum and renal hs-CRP, TNF-α and IL-6, the phosphorylation of NF-κBp65 (p-NF-κBp65) and the levels of sCr and BUN were obviously increased in the MI group. Compared with the MI group, AIT decreased the expressions of renal CD40 mRNA and protein, the levels of serum and renal hs-CRP, TNF-α and IL-6 and the expression of p-NF-κBp65, as well as decreased the levels of sCr and BUN in the ME group. CONCLUSIONS: AIT reduces the expressions of renal CD40 protein and mRNA, inhibits NF-κB signaling pathway, and then decreases the levels of inflammatory factors thereby improve the renal dysfunction after MI.

SIRT1 regulates lipopolysaccharide-induced CD40 expression in renal medullary collecting duct cells by suppressing the TLR4-NF-κB signaling pathway.

AIMS: Recent evidence indicates that sirtuin1 (SIRT1), an NAD+-dependent deacetylase, exerts a protective effect against inflammatory kidney injury by suppressing pro-inflammatory cytokines production. The co-stimulatory molecule, CD40, is expressed in a variety of inflammatory diseases in the kidney. Here, we aimed to investigate the potential effect of SIRT1 on CD40 expression induced by lipopolysaccharide (LPS) and to disclose the underlying mechanisms in renal inner medullary collecting duct (IMCD) cells. MAIN METHODS: mRNA and protein expressions were identified by quantitative real-time PCR and Western blot respectively. Subcellular localization of SIRT1 and CD40 were respectively detected by immunofluorescence and immunohistochemical staining. Small-interfering RNA (siRNA) was carried out for mechanism study. KEY FINDINGS: LPS reduced SIRT1 expression and up-regulated the expression of CD40, Toll-like receptor 4 (TLR4) and phospho-NF-κBp65 (p-NF-κBp65) in time- and concentration-dependent manners. Moreover, SIRT1 overexpression or activation by SRT1720 diminished the expression of CD40, TLR4 and p-NF-κBp65, which was reversed by SIRT1 siRNA or inhibitors Ex527 and sirtinol in LPS-stimulated IMCD cells. In addition, knockdown of TLR4 decreased the expression of CD40 and p-NF-κBp65 in IMCD cells exposed to LPS. Knockdown of NF-κBp65 or NF-κBp65 inhibition by pyrrolidine dithiocarbamate (PDTC) reduced LPS-induced CD40 expression in IMCD cells. Importantly, the inhibitory effect of SIRT1 on the expression of CD40 and p-NF-κBp65 was augmented by pre-treating with TLR4 siRNA. SIGNIFICANCE: Our data indicate that SIRT1 inhibits LPS-induced CD40 expression in IMCD cells by suppressing the TLR4-NF-κB signaling pathway, which might provide novel insight into understanding the protective effect of SIRT1 in kidney.