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Leukemia inhibitory factory (LIF), as a member of the IL-6 family, has been reported to ameliorate myocardial fibrosis and myocardial cell death. The purpose of the present study was to investigate the effect of LIF on renal fibrosis and its underlying mechanism. Our results showed, first, that LIF inhibited collagen type 1 and collagen type 3 expression induced by ANG II in NRK-49F (rat kidney fibroblast) cells and in mice with unilateral ureteral obstruction. Second, LIF induced Stat3 Tyr705phosphorylation and inhibited Stat3 Tyr705and Ser727phosphorylation induced by ANG II in NRK-49F cells. Third, LIF exerted an antirenal fibrosis effect mainly through activation of Stat3 Tyr705phosphorylation in NRK-49F cells. These effects of LIF were not observed in Stat3−/−cells. Finally, LIF-Stat3 upregulated microRNA-29c expression, and the latter downregulated collagen type 1 and collagen type 3 expression in NRK-49F cells and in mice with unilateral ureteral obstruction. In conclusion, LIF played a role in antirenal fibrosis by competitively activating Stat3 Tyr705phosphorylation, which upregulated microRNA-29c to suppress collagen expression.

To explore the relationship between the signal transducer and activator of transcription 3 (STAT3) signaling and renal fibrosis. Rat renal tubular epithelial NRK-52E cells were treated with angiotesin II (Ang II), nicotinamide (an inhibitor of NAD+-dependent class III protein deacetylases, SIRT1-7), or resveratrol (an activator of SIRT1). Mice underwent unilateral ureteral obstruction (UUO) were used for in vivo studies. Renal interstitial fibrosis was observed with HE and Masson's trichrome staining. STAT3 acetylation and phosphorylation, fibronectin, collagen I, collagen IV, and α-smooth muscle actin (α-SMA) levels were examined using Western blotting. Nicotinamide (0.625–10 mmol/L) dose-dependently increased STAT3 acetylation on Lys685 and phosphorylation on Tyr705 in NRK-52E cells, accompanied by accumulation of fibronectin and collagen IV. Ang II increased STAT3 phosphorylation on Tyr705 and the expression of fibronectin, collagen IV and α-SMA in the cells. Pretreatment with resveratrol (12.5 μmol/L) blocked Ang II-induced effects in the cells. UUO induced marked STAT3 phosphorylation, fibronectin, collagen IV and α-SMA accumulation, and renal interstitial fibrosis in the obstructed kidneys, which were significantly attenuated by daily administration of resveratrol (100 mg/kg). STAT3 acetylation plays an important role in activation of STAT3 signaling pathway and consequent renal fibrosis.

To explore the signal transducer and activator of transcription 3 (STAT3) signaling pathway, especially STAT3 acetylation, in angiotensin II (Ang II)-induced pro-fibrotic responses in renal tubular epithelial cells. Rat renal tubular epithelial cell line (NRK-52E) was used. STAT3 acetylation and phosphorylation, as well as the expression of fibronectin, collagen IV and transforming growth factor-β1 (TGF-β1) were examined using Western blotting. The level and localization of STAT3 phosphorylation on Tyr705 were detected with fluorescence immunocytochemistry. The cells were transfected with a plasmid vector carrying p300 gene or siRNA targeting p300 to regulate p300 expression. Overexpression of p300 significantly increased STAT3 acetylation on Lys685, STAT3 phosphorylation on Tyr705, and the expression of TGF-β1, collagen IV and fibronectin in the cells. Treatment of the cells with Ang II (1 μmol/L) significantly increased STAT3 phosphorylation on Tyr705 through JAK2 activation, and dose-dependently increased the expression of fibronectin, collagen IV and TGF-β1. Pretreatment with curcumin, an inhibitor of JAK2 and p300, blocked Ang II-induced effects. Knockdown of p300 significantly decreased STAT3 acetylation on Lys685, and abolished Ang II-stimulated STAT3 phosphorylation on Tyr705, whereas pretreatment of the cells with C646, a selective inhibitor of p300, inhibited Ang II-induced STAT3 nuclear translocation and the expression of TGF-β1, collagen IV and fibronectin. Pretreatment of the cells with AG490, a JAK2 inhibitor, markedly inhibited Ang II-induced STAT3 phosphorylation on Tyr705 and fibronectin expression. p300-dependent STAT3 acetylation is necessary for Ang II-induced STAT3 phosphorylation and the consequent pro-fibrotic responses in renal tubular epithelial cells in vitro.

The present study was to determine whether candesartan, an angiotensin II type 1 receptor blocker (ARB), exerts anti-inflammatory effects through inhibiting the toll-like receptor 4 (TLR4) pathway in human renal tubular epithelial cells (HKCs). The experiments were carried on cultured HKCs. By means of flow cytometry, Western blot, RT-PCR and ELISA techniques, the TLR4 protein, angiotensin II type 1 receptor (AT1R) and phosphorylated nuclear factor-kappa B (NF-κB) p65 protein level, mRNA levels of macrophage chemoattractant protein-1 (MCP-1) and regulated upon expression normal T cell expressed and secreted (RANTES), as well as MCP-1 and RANTES protein concentrations in conditioned media were measured. The results showed that lipopolysaccharide (LPS) upregulated the TLR4 protein level in cultured HKCs. Application of LPS increased NF-κB activation and induced release of its downstream inflammatory factors including MCP-1 and RANTES. Candesartan reversed LPS-induced upregulation of TLR4 expression, inhibited NF-κB activation, and reduced MCP-1 and RANTES release. However, knockdown on AT1R by siRNA did not change those previous effects of candesartan. These results suggest that candesartan-induced anti-inflammatory effect may be through a novel pathway, independent of AT1R.

To inquire into interleukin-10 (IL--10) level and monocyte expression of human leukocyte antigen--DR (HLA--DR) are predictors of infection and prognosis in critically ill patients undergoing continuous renal replacement therapy (CRRT).A total of 43 critically ill patients undergoing continuous veno-venous hemofiltration (CVVH) were recruited from the intensive care unit (ICU). Anti--coagulated blood was obtained at 1 day before and 4 days after undergoing CVVH, and plasma IL--10 level (enzyme linked immunosorbent assay) and HLA--DR expression (flow cytometry) were determined. Thirty healthy subjects were enrolled as controls. In addition, the correlation between IL--10 and acute physiology and chronic health evaluation II (APACHEII) score was assessed.(1)Altogether, 7 patients died among a total of 43 critically ill patients, the mortality was 16.3%. Eighteen patients had negative cultures during the study (group I), and 19 patients had positive cultures (group II), and in 6 patients positive bacterial culture appeared 72 hours after the beginning of the treatment (group III). (2) The IL--10 level (ng/L) was higher in patients than in healthy subjects [23.46 (46.71) vs. 0.32 (0.45), P0.01]. Compared with group I, the levels of IL--10 in group II and III were higher significantly [40.20 (46.44), 41.78 (49.63) vs. 7.33 (21.05), both P0.05]. Continuous observation revealed that IL--10 rapidly lowered in group I after treatment [4.50 (7.44) vs. 7.33 (21.05), P0.05], while there was no apparent change in patients of other two groups. It was found that IL--10 was significant positive correlation with the APACHEII score (r = 0.71, P0.01).(3) HLA--DR was lower in patients than in healthy individuals [21.65% (25.62%) vs. 90.39% (9.80%), P0.01]. After CVVH, HLA--DR expression was obviously increased in group I [64.95% (35.03%) vs. 32.45% (45.03%), P0.01]. However, there were no significant changes in the other two groups. The patients who died had persistent and extremely low HLA--DR expression.(1)A significant discriminative power of IL--10 levels in predicting disease severity was found among the patients receiving CRRT, and persistently high IL--10 level predicts poor prognosis. (2) Persistently low monocyte HLA--DR expression may indicate concomitant or impending infection in patients receiving CRRT.