Yan Ou

Sorafenib ameliorates renal fibrosis through inhibition of TGF-β-induced epithelial-mesenchymal transition.

Objective This study was to investigate whether sorafenib can inhibit the progression of renal fibrosis and to study the possible mechanisms of this effect. Methods Eight-week-old rats were subjected to unilateral ureteral obstruction (UUO) and were intragastrically administered sorafenib, while control and sham groups were administered vehicle for 14 or 21 days. NRK-52E cells were treated with TGF-β1 and sorafenib for 24 or 48 hours. HE and Masson staining were used to visualize fibrosis of the renal tissue in each group. The expression of α-SMA and E-cadherin in kidney tissue and NRK-52E cells were performed using immunohistochemistry and immunofluorescence. The apoptosis rate of NRK-52E cells was determined by flow cytometry analysis. The protein levels of Smad3 and p-Smad3 in kidney tissue and NRK-52E cells were detected by western blot analysis. Results HE staining demonstrated that kidney interstitial fibrosis, tubular atrophy, and inflammatory cell infiltration in the sorafenib-treated-UUO groups were significantly decreased compared with the vehicle-treated-UUO group (p<0.05). Masson staining showed that the area of fibrosis was significantly decreased in the sorafenib-treated-UUO groups compared with vehicle-treated-UUO group (p<0.01). The size of the kidney did not significantly increase; the cortex of the kidney was thicker and had a richer blood supply in the middle-dose sorafenib group compared with the vehicle-treated-UUO group (p<0.05). Compared with the vehicle-treated-UUO and TGF-β-stimulated NRK-52E groups, the expression of a-SMA and E-cadherin decreased and increased, respectively, in the UUO kidneys and NRK-52E cells of the sorafenib-treated groups (p<0.05). The apoptotic rate of NRK-52E cells treated with sorafenib decreased for 24 hours in a dose-dependent manner (p<0.05). Compared with the vehicle-treated UUO and TGF-β-stimulated NRK-52E groups, the ratio of p-Smad3 to Smad3 decreased in the sorafenib-treated groups (p<0.05). Conclusion Our results suggest that sorafenib may useful for the treatment of renal fibrosis through the suppression of TGF-β/Smad3-induced EMT signaling.

TIPE2, a Novel Biomarker for Clinical Chronic Kidney Allograft Rejection

Tumor necrosis factor-a--induced protein 8-like 2 (TIPE2) has an essential role in immune homeostasis, yet the relationship between TIPE2 expression and allograft rejection has not been addressed. Dependent on clinical diagnosis, 96 kidney transplant recipients were divided into three groups, long-term survival group, acute rejection group (AR) and chronic rejection group (CR). Thirty-two healthy volunteers were used as a control group. The expression of TIPE2 in peripheral blood mononuclear cells (PBMC) and kidney biopsy samples was performed using reverse transcript-polymerase chain reaction, immunohistochemistry and immunofluorescence. The expression of TIPE2 in PBMC of CR group was significantly higher than that of the healthy control (P < 0.001), but TIPE2 expression in AR group was lower than that of control individuals (P < 0.05). The renal expression of TIPE2 in allograft tissue of CR was significantly lower and its expression in AR slightly lower than in normal kidneys. The positive correlation between TIPE2 expression in PBMCs and the CR of allo-kidney grafts indicates that detection of TIPE2 in the blood samples may be used as one of the diagnosis molecular markers in clinical monitoring kidney chronic rejection.

Activation of PPAR-γ inhibits PDGF-induced proliferation of mouse renal fibroblasts

Recent studies have shown that activation of peroxisome proliferators activated receptor-γ (PPAR-γ) ameliorates renal interstitial fibrosis (RIF) in animal model. Yet, the underlying molecular mechanisms remain still largely unknown. Here, we investigated the hypothesis that activation of PPAR-γ regulates renal remodeling by modulating proliferation of primary cultured renal fibroblasts. In our present study, platelet-derived growth factor-AA (PDGF-AA), a key isoform of PDGF superfamily as mitogen in RIF, was applied to stimulate renal fibroblasts, the selective inhibitor or sequence specific siRNA of PI3K, skp2 or PPAR-γ was used to investigate the involvement of above molecular mediators in PDGF-AA-induced cell proliferation. Our results demonstrate that PDGF-AA induced proliferation of renal fibroblasts by activating PI3K/AKT signaling and resultant skp2 production. Pre-stimulation of cells with rosiglitazone or adenovirus carrying PPAR-γ cDNA (AdPPAR-γ) blocked PDGF-AA-stimulated cell proliferation, this effect was particularly coupled to PPAR-γ inhibition of AKT phosphorylation and skp2 expression. Inhibition of PPAR-γ by GW9662 restored the suppression of activated PPAR-γ on phosphorylation of AKT and subsequent skp2 production. Our results indicate that activation of PI3K/AKT signaling and resultant skp2 generation mediated PDGF-induced proliferation of renal fibroblasts. Activation of PPAR-γ inhibited cell proliferation by inhibition of AKT phosphorylation and its down-streams.

Sodium Citrate Inhibits Endoplasmic Reticulum Stress in Rats with Adenine-Induced Chronic Renal Failure.

Background/Aims: Endoplasmic reticulum stress (ERS) is an important self-protective cellular response to harmful stimuli that contribute to various diseases, including chronic renal failure (CRF). Sodium citrate plays an important role in antioxidant and cellular immunity, but whether it improves ERS in CRF is unclear. Methods: The rats were randomly divided into five groups: the control group, the sodium citrate control group, the model group, model rats with low dose sodium citrate (216 mg/kg), and model rats with a high dose of sodium citrate (746 mg/kg). The rats were euthanized at 6, 8, 12, and 16 weeks with their blood and renal tissue in detection. Results: The increased concentrations of blood urea nitrogen and serum creatinine in the model group were significantly decreased by sodium citrate treatment. Hematoxylin-eosin and Masson staining showed that sodium citrate treatment apparently improved renal pathological changes in CRF rats. Western blot analysis showed that sodium citrate treatment decreased the protein levels of transforming growth factor-beta 1 and collagen type IV, which were increased in model rats. Moreover, immunohistochemical staining demonstrated that sodium citrate could effectively reduce the protein expression of glucose-regulated protein 78 kDa and CCAAT/enhancer-binding protein homologous protein in the model rats, which was consistent with western blot results. Additionally, the high dose of sodium citrate had a stronger protective effect in CRF rats than the low dose of sodium citrate. Conclusions: Sodium citrate has a protective effect on CRF through its effects on ERS.

Citrate Attenuates Adenine-Induced Chronic Renal Failure in Rats by Modulating the Th17/Treg Cell Balance.

Citrate is commonly used as an anticoagulant in hemodialysis for chronic renal failure (CRF) and for the regulation of the immune dysfunction in CRF patients. The objective of this study was to investigate the effect of citrate on the balance of T helper 17 (Th17) and regulatory T (Treg) cells in CRF. The levels of blood urea nitrogen (BUN) and serum creatinine (Scr) were significantly increased in the CRF model group compared to the control group, and were decreased in the citrate-treated groups. Citrate treatment inhibited the viability of Th17 cells while elevating the viability of Treg cells in CRF rats. Moreover, Th17-related cytokines significantly decreased while the Treg-related cytokines significantly increased with citrate treatment. Moreover, citrate had a negative influence on the deviation of Th17/Treg cells in CRF rats. Therefore, our study suggests that citrate had an anti-inflammatory effect on CRF through the modulation of the Th17/Treg balance.

The Endothelial Nitric Oxide Synthase Gene Polymorphism is Associated with the Susceptibility to Immunoglobulin a Nephropathy in Chinese Population

Background/Aims: Endothelial nitric oxide synthase (eNOS) is one of the most important enzymes for producting nitric oxide (NO), which regulate the function of many organs and cells. The single nucleotide polymorphisms (SNPs) of eNOS were found to be associated with many kidney diseases. However, it is lack of relevant studies to evaluate the associations between eNOS polymorphisms and immunoglobulin A nephropathy (IgAN). This case-control study aimed to evaluate the relationship between eNOS polymorphisms and IgAN. Methods: We recruited 351 IgAN patients and 310 age- and sex-matched healthy controls from Northwest China. Sequenom MassARRAY was used to detect the genotypes of two common eNOS SNPs (rs1799983 and rs2070744). Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated by the Chi square test to evaluate the associations between eNOS and IgAN. Phase 2.1 was used to conduct haplotype analysis. Results: In the overall analysis, we found that the rs1799983 polymorphism was associated with a decreased risk of IgAN (G/T vs. G/G: OR=0.57, 95%CI=0.34–0.96; G/T+T/T vs. G/G: OR=0.52, 95%CI=0.31–0.86; G/T vs. G/G-T/T: OR=0.60, 95%CI=0.36–0.99; Log-additive model: OR=0.48, 95%CI=0.30–0.78). Haplotype analysis indicated that Trs1799983Crs2070744 is a protective factor against IgAN (OR=0.62, 95%CI=0.42––0.92). However, no significant differences were found between the two SNPs (rs1799983 and rs2070744) and clinical features (age, sex, blood pressure, and Lee’s grade) of IgAN. Conclusion: The eNOS gene rs1799983 polymorphism and Trs1799983Crs2070744 haplotype may reduce the risk of IgAN in Chinese populations.

Citrate attenuates vascular calcification in chronic renal failure rats

Vascular calcification (VC) is a major contributor of cardiovascular dysfunction in chronic renal failure (CRF). Citrate binds calcium and inhibits the growth of calcium crystals. This present study intends to evaluate the effect of citrate on VC in adenine‐induced CRF rats. The rats were randomly divided into five groups: the control group, the citrate control group, model group, model rats with low‐dose treatment of citrate (216 mg/kg) and model rats with high‐dose treatment of citrate (746 mg/kg). The rats were euthanized at 5 weeks with their blood and aorta in detection. The results showed that serum level of blood urea nitrogen, serum creatinine, phosphorus, calcium, and related renal failure function marker were elevated in the model group. Furthermore, the aortic calcium accumulation and alkaline phosphatase activity were significantly increased in the model group compared with control groups. Additionally, hematoxylin–eosin staining results demonstrated that the vascular calcification in aorta is significantly increased in the model group. Finally, the expression of VC‐related proteins including bone morphogenetic protein and osteocalcin were increased in the model group, whereas alpha‐smooth muscle actin was decreased in the model group compared with the control group. However, treatment with citrate caused a reversal effect of all the above events in a dose‐dependent manner. In conclusion, citrate may attenuate vascular calcification in adenine‐induced CRF rats.