SIRT1 regulates TNF-α-induced expression of CD40 in 3T3-L1 adipocytes via NF-κB pathway.

Sirtuin1 (SIRT1), a NAD(+)-dependent deacetylase, not only regulates lipid and glucose homeostasis, but also involves the regulation of proinflammatory cytokine involved in inflammation-associated diseases. The activation of CD40 triggers inflammation that plays a crucial role in the development of many chronic inflammatory diseases including obesity. Growing evidence indicated that SIRT1 exerts anti-inflammatory properties by suppressing proinflammatory cytokines production. However, the effect of SIRT1 on the expression of CD40 in adipocytes has not yet been fully elucidated. The present study showed that SIRT1 expressed both in the nucleus and cytoplasm of 3T3-L1 adipocytes. TNF-α significantly reduced the expression of SIRT1 mRNA and protein and increased the expression of CD40 mRNA and protein in time- and concentration-dependent manners. Overexpression of SIRT1 or SIRT1 activation by resveratrol obviously attenuated the expression of CD40 induced by TNF-α in 3T3-L1 adipocytes, whereas knockdown of SIRT1 or SIRT1 inhibition by nicotinamide and sirtinol significantly enhanced TNF-α-induced expression of CD40. Furthermore, overexpression of SIRT1 or SIRT1 activation by resveratrol diminished TNF-α-induced acetylation of NF-κBp65, while knockdown of SIRT1 or SIRT1 inhibition by nicotinamide and sirtinol augmented TNF-α-induced acetylation of NF-κBp65 in 3T3-L1 adipocytes. NF-κB inhibitor PDTC reduced TNF-α-induced mRNA and protein expression of CD40 in 3T3-L1 adipocytes. The combination treatment of resveratrol and PDTC significantly reduced TNF-α-induced expression of CD40, and the inhibitory effects were higher than that of the single treatment. Taken together, SIRT1 exerts anti-inflammatory property by regulating TNF-α-induced expression of CD40 partially through the NF-κB pathway in 3T3-L1 adipocytes. More importantly, the regulation of SIRT1 on the expression of CD40 provides new insight to understand the anti-inflammatory effects of SIRT1.

Effect of exercise training on renal function and renal aquaporin-2 expression in rats with chronic heart failure.

1. Chronic heart failure (CHF) is often accompanied by renal dysfunction. Exercise training may relieve the symptomatic burden and improve the overall prognosis of CHF. In the present study, the effects of exercise training on renal function and renal aquaporin (AQP)-2 expression in CHF rats were examined to determine whether exercise training could relieve renal dysfunction in CHF rats. 2. Male Sprague-Dawley rats were divided into three groups: sham, sedentary CHF (Sed-CHF) and exercise training CHF (Ex-CHF) groups. Cardiorenal function was assessed in each group by haemodynamic measurement and ultraviolet spectrophotometry. Pathological changes in cardiac and renal tissues were evaluated histologically and the collagen volume fraction (CVF) was calculated. The expressions of AQP-2 and ß-tubulin were determined by western blotting and immunohistochemistry. 3. The Sed-CHF rats were found to have increased left ventricular end-diastolic pressure (LVEDP) and CVF in the heart compared with sham rats. Exercise training decreased LVEDP and CVF values in Ex-CHF rats. The Sed-CHF rats were found to have increased serum levels of creatinine (sCr), blood urea nitrogen (BUN) and arginine vasopressin (AVP), as well as increased CVF in the kidney, compared with sham rats. Exercise training decreased levels of sCr, BUN, AVP and CVF in Ex-CHF rats. Moreover, exercise training decreased AQP-2 and ß-tubulin protein expression in the kidney of CHF rats. 4. The results suggest that exercise training can significantly improve the renal dysfunction in CHF rats and that the underlying mechanism may be related to water reabsorption and preventing changes to the cytoskeleton.

[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.

Exercise training activates neuregulin 1/ErbB signaling and promotes cardiac repair in a rat myocardial infarction model.

AIMS: Exercise training (ET) has a cardioprotective effect and can alter the molecular response to myocardial infarction (MI). The Neuregulin 1 (NRG1)/ErbB signaling plays a critical role in cardiac repair and regeneration in the failing heart. We sought to investigate whether ET following MI could activate the NRG1/ErbB signaling and promote cardiac repair and regeneration. MAIN METHODS: Male Sprague-Dawley rats were used to establish the MI model. Exercise-trained animals were subjected to four weeks of exercise (16m/min, 50min/d, 5d/wk) following the surgery. AG1478 was used as an inhibitor of ErbB (1mg/kg body weight, administered i.v. every other day during the process of training). NRG1/ErbB signaling activation, cardiomyocyte (CM) proliferation and apoptosis were evaluated. KEY FINDINGS: In the exercise-trained rats, NRG1 expression was up-regulated and ErbB/PI3K/Akt signaling was activated compared with the MI group. In addition, ET preserved heart function accompanied with increased numbers of BrdU(+) CMs, PCNA(+) CMs and c-kit(+) cells, and reduced apoptosis level in the MI rats. In contrast, blocking ErbB signaling by AG1478 attenuated the ET-induced cardiac repair and regeneration. SIGNIFICANCE: ET up-regulates NRG1 expression and activates ErbB2, ErbB4 and PI3K/Akt signal transduction to promote cardiac repair through endogenous regeneration. Activation of ErbB may be an underlying mechanism for the ET-induced cardiac repair and regeneration following MI.

The effects of Buyang Huanwu Decoction on hemorheological disorders and energy metabolism in rats with coronary heart disease.

ETHNOPHARMACOLOGICAL RELEVANCE: Buyang Huanwu Decoction (BYHWD), a traditional Chinese medicine (TCM) formula, has been recognized as a clinical treatment for coronary heart disease (CHD) with qi deficiency and blood stasis syndrome. The effects of BYHWD on hemorheological disorders and energy metabolism in CHD with qi deficiency and blood stasis syndrome are still unclear. AIM OF THE STUDY: To investigate whether the ameliorative effects of BYHWD on CHD rats with qi deficiency and blood stasis syndrome are associated with the regulation of hemorheological disorders and energy metabolism. MATERIALS AND METHODS: The rats were lavaged with 25.68, 12.84 and 6.42 g/kg BYHWD (g weight of mixed crude drugs/kg body weight), respectively, once a day for 21 days. The body weight, exhaustive swimming time and tongue characters were observed and recorded. The whole blood viscosity and plasma viscosity were determined by hematology analyzer. The level of fibrinogen (Fbg) in plasma was determined by using Fbg assay kit. The platelet aggregation induced by adenosine diphosphatase was measured by semi-automatic whole blood platelet analyzer. The level of blood glucose (BG) was determined by LifeScan. The activity of Na(+)-K(+)-ATPase in heart tissues was detected by spectrophotometer. RESULTS: BYHWD improved the exterior signs of qi deficiency and blood stasis syndrome in rats with CHD, including the body weight, exhaustive swimming time and tongue quality. The whole blood viscosity in rats treated with 25.68 g/kg BYHWD decreased at the shear rate of 10s(-1) (P<0.05) and the plasma viscosity decreased in rats treated with 25.68 and 12.84 g/kg BYHWD (P<0.05). The plasma Fbg level and the platelet aggregation decreased in rats treated with 25.68 g/kg BYHWD (P<0.01). The results also revealed that the BG level decreased and the Na(+)-K(+)-ATPase activity in heart tissues increased in rats treated with 25.68 and 12.84 g/kg BYHWD (P<0.01). CONCLUSION: The results suggest that the ameliorative effects of BYHWD on CHD rats with qi deficiency and blood stasis syndrome are mediated by the improvement of hemorheological disorders and energy metabolism.

Buyang Huanwu decoction ameliorates coronary heart disease with Qi deficiency and blood stasis syndrome by reducing CRP and CD40 in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Qi deficiency and blood stasis is traditional Chinese medicine (TCM) syndrome. It leads to many diseases including coronary heart diseases (CHD) and cerebrovascular diseases (CVD). Inflammatory biomarkers and many endothelium-derived vasoactive factors are considered to play pivotal roles in CHD. Buyang Huanwu decoction (BYHWD), a TCM formula, has been recognized as a treatment for CHD with Qi deficiency and blood stasis syndrome and CVD in clinic. The mechanisms of BYHWD effect on CHD with Qi deficiency and blood stasis syndrome are unclear. AIM OF THE STUDY: The aim is to investigate whether the effects of BYHWD on CHD with Qi deficiency and blood stasis syndrome in rats are associated with the inhibition of CRP, CD40 and vascular endothelial regulators. MATERIALS AND METHODS: The treated groups were lavaged with 25.68, 12.84 and 6.42 g/kg BYHWD respectively once a day for 21 days. The level of C-reactive protein (CRP) in serum and the expression of cluster of differentiation 40 (CD40) in the heart and aorta of rats were detected. Moreover, the levels of thromboxaneA(2) (TXA(2)) and prostacyclin (PGI(2)) in plasma were measured and the levels of inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) in serum were detected. RESULTS: BYHWD (25.68 g/kg) significantly decreased the level of CRP in serum and BYHWD (25.68 and 12.84 g/kg) decreased the expression of CD40 in the heart and aorta (P<0.01). The results also revealed that BYHWD (25.68 g/kg) inhibited the levels of iNOS in serum and TXA(2) in plasma and increased the levels of eNOS in serum and PGI(2) in plasma (P<0.01). CONCLUSION: The study shows that the ameliorative effects of BYHWD on CHD with Qi deficiency and blood stasis syndrome in rats are associated with the inhibition of CRP and CD40 and the regulation of endothelium-derived vasoactive factors.