Role of tea polyphenols in delaying hyperglycemia-induced senescence in human glomerular mesangial cells via miR-126/Akt-p53-p21 pathways.

PURPOSE: The aim of this study was to investigate the effects and possible mechanism of tea polyphenols (TPs) on the senescence of human glomerular mesangial cells (HGMCs) under high glucose conditions. METHODS: HGMCs were divided into the normal group (NG, 5.5 mmol/L glucose), mannitol group (MNT, 5.5 mmol/L glucose and 24.5 mmol/L mannitol), TP group (TP, 30 mmol/L glucose and 5 µg/mL TP) and high-dose D-glucose group (HG, 30 mmol/L glucose). The effects of TP on the cell morphology of HGMCs; the percentage of cells positive for senescence-associated ß-galactosidase (SA-ß-gal); the ratio of G1 phase of cell cycle; telomere length; and the expression of p-Akt, p53, p21 and Rb proteins of the Akt-p53-p21 signaling pathway and the expression miR-126 were examined. RESULTS: High glucose led to premature senescence of HGMCs, as evident from the increase in the percentage of SA-ß-gal-positive cells, decrease in telomere length, cell cycle arrest at G1 phase,decrease in the expression of miR-126 and p-Akt and increase in the expression of p53, p21 and Rb proteins in the HG group. In contrast, in the TP group, these effects of high glucose treatment were abrogated and this indicates that TP had a protective effect on HGMCs. CONCLUSIONS: High glucose induces the senescence of HGMCs in vitro via the miR-126 and Akt-p53-p21 signaling pathways. TP can delay the high glucose-induced senescence of HGMCs by regulating the activity of these signaling pathways. Thus, the polyphenols present in tea may have potential for the treatment of diabetic nephropathies associated with premature senescence.

Vitamin D supplementation improves endothelial dysfunction in patients with non-dialysis chronic kidney disease.

PURPOSE: Hypovitaminosis D is common in chronic kidney disease (CKD) and is associated with endothelial dysfunction and cardiovascular events. This study aimed to investigate the effects of vitamin D supplementation on endothelial dysfunction in non-dialysis CKD patients. MATERIALS AND METHODS: Seventy-one non-dialysis CKD patients with low vitamin D (serum 25(OH)D < 30 ng/mL) were recruited. Patients received oral cholecalciferol 50,000 units once a week for 12 weeks. Changes in endothelial function by brachial artery flow-mediated dilation (FMD), soluble vascular cell adhesion molecule-1 (sVCAM-1), and sE-selectin were studied. RESULTS: There was a significant increase in serum levels of 25(OH)D after cholecalciferol supplementation (33.7 ± 12.1 vs. 13.2 ± 5.4 ng/mL, P < 0.001). Multivariable regression analysis showed that higher proteinuria (ß = - 0.548, P < 0.001) and lower levels of 25(OH)D (ß = 0.360, P < 0.001) at baseline were related to lower 25(OH)D level after supplementation. FMD increased significantly from 4.4 ± 1.3 to 5.1 ± 1.5% (P < 0.001), and soluble endothelial biomarkers decreased: sVCAM-1 from 926.9 ± 158.0 to 867.0 ± 129.0 ng/mL (P < 0.001), and sE-selectin 69.7 ± 15.8 to 63.3 ± 14.7 ng/mL (P < 0.001). CONCLUSIONS: Vitamin D supplementation can improve endothelial dysfunction in pre-dialysis CKD patients.

Hypovitaminosis D is associated with endothelial dysfunction in patients with non-dialysis chronic kidney disease.

OBJECTIVE: Cardiovascular events are highly prevalent in chronic kidney disease (CKD). Hypovitaminosis D and vascular endothelial dysfunction are risk factors for cardiovascular morbidity and mortality and they both are common in CKD patients. This study aimed to investigate the association between hypovitaminosis D and endothelial dysfunction in non-dialysis CKD patients. METHODS: In 117 non-dialysis CKD patients, we assessed endothelial function by brachial artery flow-mediated dilation (FMD), soluble vascular cell adhesion molecule-1 (sVCAM-1) and sE-selectin. 25-hydroxyvitamin D [25(OH)D] was measured by electrochemiluminescence immunoassay. RESULTS: Brachial artery FMD was lower in vitamin D-deficient and -insufficient versus vitamin D-sufficient groups, with the lowest value observed in the vitamin D-deficient group. Conversely, sVCAM-1 and sE-selectin were higher in vitamin D-deficient and -insufficient groups versus vitamin D-sufficient, and the highest value was observed in the vitamin D-deficient group. There was a positive association between FMD and 25(OH)D (r = 0.556, p < 0.001) and negative correlations between both sVCAM-1 (r = -0.549, p < 0.001) and sE-selectin (r = -0.360, p < 0.001) and 25(OH)D. These associations remained significant after adjusting for confounders. CONCLUSIONS: Hypovitaminosis D is associated with endothelial dysfunction in non-dialysis CKD patients. Further studies are needed to confirm whether vitamin D supplementation can improve endothelial function and reduce cardiovascular events in these patients.

[Proapoptotic effect of angiotensin II on renal tubular epithelial cells and protective effect of Cordyceps sinensis].

OBJECTIVE: To investigate the mechanism of the protective effect of Cordyceps sinensis (C. sinensis) on the apoptosis of cultured NRK-52E induced by angiotension II (AngII). METHODS: NRK-52E cells were incubated with C. sinensis (0, 5, 10, 20, and 40 mg/L) and 10(-8) mol/ L AngII for 24, 48, 72 h. The optimal concentration of C. sinensis was selected. Either NRK-52E cells were incubated with different doses of AngII (0, 10(-12), 10(-10), 10(-8), and 10(-6) mol/L) for 24 h, or with 10(-8) mol/L AngII for 24, 48, and 72 h, to observe the effect of AngII on the apoptosis of NRK- 52E cells. The optimal concentration and time of AngII were selected. In another experiment cells were divided into 5 groups: a control, AngII (10(-8) mol/L), AngII (10(-8) mol/L)+ C. sinensis (40 mg/ L), Ang II (10(-8) mol/L)+ fosinopril (10(-5) mmol/L), and Ang II (10(-8) mol/L)+ fosinopril (10(-5) mol/ L)+C. sinensis (40 mg/L). MTT assay was used to test the changes in the proliferation of NRK-52E cultured with different concentration of C. sinensis for 24, 48, 72 h. The Annecxin V-FITC and PI stainings were applied to detect the apoptosis rate induced by AngII by flow cytometer (FCM) and to determine the eddects of C. sinensis. The activity of caspase-3 was assayed by spectrophotometry. RESULTS: Certain concentrations of C. sinensis (10-40 mg/L) promoted the proliferation of NRK- 52E cells inhibited by AngII(P<0.05). AngII induced the apoptosis of NRK-52E in a dose and timedependent manner, accompanied with increased activity of caspase-3 (P<0.05). C. sinensis partially suppressed the apoptosis of NRK-52E induced by AngII, and declined the activity of caspase-3 (P<0.05). No significant difference was shown as between the fosinopril group and the fosinopril+C. sinensis group (P>0.05). CONCLUSION: C. sinensis can suppress the apoptosis of NRK-52E by AngII, and the protective effect of C. sinensis may be inhibiting the activation of caspase-3 during the AngII-induced apoptosis of NRK-52E.

[Effect of cordyceps sinensis extract on Klotho expression and apoptosis in renal tubular epithelial cells induced by angiotensin II].

OBJECTIVE: To investigate the effect of cordyceps sinensis (CS) extract and losartan (Los) on the expression of Klotho (Kl), P53, P21, and apoptosis in renal tubular epithelial cell NRK-52E induced by angiotensin II (Ang II), and to elucidate its therapeutical mechanism in Ang II induced renal tubular epithelial cell apoptosis. METHODS: NRK-52E cells were incubated with CS with or without Ang II for 24 hours. Experimental groups were divided according to the increasing concentrations of CS:0 (serving as controls), 5, 10, 20, 40, and 80 mg/L. The optimal concentration of CS was selected and cells were divided into 5 groups: controls, Ang II (1*10(-8) mol/L), Ang II (1*10(-8) mol/L)+CS (40 mg/L), Ang II (1*10(-8) mol/L)+Los (1*10(-5) mol/L), and Ang II (1*10(-8) mol/L)+CS (40 mg/L)+Los (1*10(-5) mol/L). After 24 hours, cell proliferation was evaluated by MTT assay. The mRNA and protein expression of Kl, P53 and P21 were measured by RT-PCR. Activity of caspase-3 was evaluated by caspase-3 activity assay Kit. Cell apoptosis was determined by Annexin V-FITC/PI double staining and flow cytometry. RESULTS: Certain concentrations of CS promoted the proliferation of NRK-52E cells and increased cells proliferation inhibited by Ang II (P<0.01 or P<0.05 ). Ang II significantly down-regulated the mRNA and protein expression of Kl, and up-regulated the levels of P53 and P21. Caspase-3 activity and apoptotic rates were decreased, too (all P values<0.01). CS or/and Los significantly increased the expression of Kl mRNA and protein down-regulated by Ang II, decreased P53 mRNA and protein expression, P21 mRNA and protein expression,and inhibited caspase-3 activity and apoptotic rates(all P values<0.05). No cooperative effects were observed in the two drugs (P>0.05). CONCLUSION: CS can increase the expression of Kl down-regulated by Ang II, decrease P53 and P21 expression and caspase-3 activity, and reduce Ang II induced NRK-52E cell apoptosis, which may be part of its mechanism of the protective effects on hypertensive renal damage.

[Effect of bizhongxiao decotion on TNF-alpha and interleukin-1beta in plasma of rats with C II-induced rheumatoid arthritis].

OBJECTIVE: To observe the influence of bizhongxiao decotion (BZXD) on the plasma TNF-alpha and IL-1beta in rats with C II-induced arthritis (CIA) and to explore the mechanism of BZXD in the treatment of rheumatoid arthritis. METHODS: We divided 75 rats into 4 groups randomly. The rat experimented arthritis model was established by subcutaneous injection with collagen II. The plasma TNF-alpha and IL-1beta levels were detected with the radio-immunity assay at different time spots. RESULTS: The incidence of arthritis in the rats immunized with C II was approximately 88%. The plasma TNF-alpha and IL-1beta levels of the model group, BZXD group and methotrexate (MTX) group were notably higher than those of the normal group (P < 0.05). The plasma TNF-alpha and IL-1beta levels of the model group were higher than those of the MTX control group and BZXD treatment group at different time spots (P < 0. 01). The plasma TNF-alpha and IL-1beta levels rose step by step, but those of the BZXD group and MTX group decreased gradually. Moreover, the plasma TNF-alpha and IL-1beta levels of the rats of BZXD group were lower than those of the MTX group (P < 0. 05). CONCLUSION: TNF-alpha and IL-1beta play a very important role in the formation and development of rheumatoid arthritis. Both BZXD and MTX can notably decrease the plasma TNF-alpha and IL-1beta levels, but the effect of BZXD is better than that of MTX.