乌索酸改善高糖诱导系膜细胞损伤的机制

目的 探讨乌索酸能否通过抑制高糖状态下系膜细胞内miRNA-21的过表达,上调其靶基因PTEN的表达,抑制磷脂酰肌醇-3-激酶(PI3K)-Akt-哺乳动物雷帕霉素靶蛋白(mTOR)信号通路的激活,诱导自噬,减少细胞外基质堆积,发挥其肾脏保护作用.方法 高糖培养大鼠肾小球系膜细胞,以PI3K抑制剂LY294002以及不同剂量乌索酸进行干预,应用甲基噻唑基四唑(MTT)法观察细胞增殖能力,总蛋白/总细胞数测定细胞肥大,Western印迹和实时定量PCR检测PTEN-PI3K-Akt-mTOR信号通路活性、Ⅰ型胶原及自噬标志物.透射电镜观察自噬体的形成.结果 与正常对照组相比,高糖培养的系膜细胞出现显著的肥大、增殖,细胞内miRNA-21表达明显上调,PTEN蛋白及mRNA的表达明显下调,p85PI3K、磷酸化(p)-Akt、p-mTOR、Ⅰ型胶原、p62/SQSTMI表达明显增加,LC3 II表达明显降低,差异均有统计学意义(均P＜ 0.01).与高糖组相比,乌索酸干预组及LY294002组细胞肥大、增殖程度均明显降低,p85PI3K、p-Akt、p-mTOR、Ⅰ型胶原、p62/SQSTMI的表达均明显降低,LC3 II表达明显升高,差异均有统计学意义(均P＜ 0.01);但LY294002组细胞内miRNA-21和PTEN的表达与高糖组差异无统计学意义,而乌索酸干预组细胞内miRNA-21的表达明显下调,PTEN的表达明显上调,差异均有统计学意义(均P＜ 0.01).结论 乌索酸可能通过抑制高糖培养系膜细胞内miRNA-21的过表达,上调PTEN表达,抑制PI3K-Akt-mTOR信号通路异常活化,增强自噬从而减少细胞外基质堆积,减轻细胞的肥大、增殖.     

Abated microRNA-21 attenuates high glucose-induced autophagy inhibition in rat mesangial cells by PTEN/Akt/mTOR pathway

Objective To investigate the effects of abated microRNA-21 (miRNA-21) on phosphatase and tensin homologue on chromosome ten protein (PTEN) and PI3K/Akt/mTOR pathway, as well as their further influence on the autophagy in high glucose (HG, 25.0 mmol/L) induced rat glomerular mesangial cells. Methods MiRNA-21 inhibitor and negative control were transfected by liposome 2000 into rat glomerular mesangial cells (HBZY-1). The cells were divided into normal glucose (5.5 mmol/L) group, normal glucose+negative control group, normal glucose+miRNA-21 inhibitor group, HG group, HG+negative control group and HG+miRNA-21 inhibitor group. Cell proliferation and hypertrophy were assayed by MTT and the ratio of total protein to cell number respectively. The miRNA-21 expression was detected using real time PCR. The expressions of PTEN/Akt/mTOR signaling signatures, autophagy-associated protein (p62 and LC3 Ⅱ) and collagen Ⅰ was detected by Western blotting and real time PCR. Autophagosomes were observed using electron microscopy. Results Compared with those in normal glucose group, in HG group cells had hypertrophy and proliferation, up-regulated miRNA-21 expression, and down-regulated PTEN protein and mRNA expressions (all P＜0.01). Also there were and up-regulated p-Akt, p-mTOR, p62 and collagen Ⅰ expression, and lower LC3 Ⅱ expression and autophagosomes (all P＜0.01). Further, compared with those in HG group, cells hypertrophy and proliferation in HG+miRNA-21 inhibitor group were reduced, expressions of p-Akt, p-mTOR, p62 and collagen Ⅰ were down-regulated, while expressions of PTEN and LC3 Ⅱ and autophagosomes were up-regulated (all P＜0.01). Conclusions MiRNA-21 inhibitor up-regulates PTEN expression, which inhibits the activation of Akt/mTOR signaling pathway, ameliorates cell hypertrophy, proliferation and enhances autophagy to reduce extracellular matrix accumulation.     

1,25(OH)2D3 ameliorates high glucose-induced podocyte injury via PI3K/p-Akt signalling pathway

Objective To investigate the effect of 1,25(OH)2D3 on high glucose induced podocyte injury and its signal transduction mechanism. Methods Differentiated mouse podocytes were exposed to normal glucose, high glucose, and different concentrations of 1,25(OH)2D3 or LY294002 (a selective PI3K inhibitor) for 24 h. PCR and immunofluorescent staining were used to detect nephrin, podocin, and desmin. Western blotting was used to detect protein expression of nephrin, podocin, desmin, PI3K, Akt and p-Akt. Results Compared with high glucose group, 1,25(OH)2D3 (100 nmol/L and 1000 nmol/L) significantly up-regulated the expression of podocin and nephrin in podocytes induced by high glucose (P＜0.05). Meanwhile, 1,25(OH)2D3 (100 nmol/L) significantly reduced the expression of desmin (P＜0.05). PI3K and p-Akt were obviously reduced in high glucose group. In the presence of 1,25(OH)2D3, the trends were reversed. However the above effects of 1,25(OH)2D3 were abolished when p-Akt was blocked by the PI3K inhibitor LY294002. Conclusions 1,25 (OH)2D3 can inhibit high glucose-induced podocyte injury through PI3K/p-Akt signaling pathway.     

高糖通过PI3K-AKT-mTOR信号通路增加足细胞自噬

目的 研究高糖引起足细胞自噬变化及其相关的信号机制.方法 培养的足细胞被分为6组,正常浓度葡萄糖(NG)组、高浓度葡萄糖(HG)组、NG+雷帕霉素(Rap)组、HG+Rap组、NG+LY294002组和HG+LY294002组.观察自噬增强剂Rap和PI3K抑制剂LY294002对高糖条件下培养的足细胞自噬和凋亡的影响.电镜和吖啶橙染色观察细胞内自噬体的形成;Western印迹检测自噬标志蛋白微管相关蛋白1轻链3(LC3)和自噬血管基因Beclin-1的表达;通过阻断自噬的信号通路观察磷脂酰肌醇3激酶-蛋白激酶B-哺乳动物雷帕霉素靶蛋白(PI3K-AKT-mTOR)相关蛋白AKT和mTOR的磷酸化水平的改变.结果 高糖可导致足细胞凋亡增加,促进足细胞内自噬体和自噬相关蛋白表达增加(均P＜ 0.05).与高糖组相比,HG+ Rap组LC3-Ⅱ和Beclin-1的表达增加(均P＜0.05);LY294002部分抑制高糖导致的LC3-Ⅱ和Beclin-1表达增加(均P＜0.05).与高糖组相比,HG+ LY294002组足细胞内AKT磷酸化的水平增加(P＜0.05),mTOR的磷酸化水平降低(P＜0.01);HG+ LY294002组足细胞的AKT和mTOR磷酸化水平较高糖组均降低(均P＜0.05).结论 高糖可促进足细胞的自噬和凋亡,推测高糖诱导的足细胞自噬作用部分通过PI3K-AKT-mTOR信号通路调节实现的.     

Oxidized LDL leads to podocyte injury through PTEN/SR-A pathway

Objective To evaluate the effect of oxidized LDL (Ox-LDL) on scavenger receptor A (SR-A) expression in mouse podocytes and to explore the possible mechanism. Methods The conditionally immortalized mouse podocyte cell line was cultured in vitro and exposed to Ox-LDL of different concentrations for 24 h, or 20 mg/L Ox-LDL for different hours. Cell cholesterol accumulation was examined. Real-time quantity PCR and Western blotting were used to analyze the expression level of PTEN, SR-A and nephrin. Podocytes were incubated with DiI labeled Ox-LDL for 4 h and immunofluorescence was used to analyze lipid uptaking. To further confirm the relationship between PTEN and SR-A, PTEN inhibitor bpv (hOpic) [dipotassium bisperoxo (5-hydroxypyridine-2-carboxyl) oxovanadate (V) ], PTEN siRNA and PTEN adenovirus (adPTEN) were used to dual-directional regulate PTEN expression, so as to observe the change of SR-A, nephrin, cell cholesterol accumulation and lipid uptake. Results SR-A was expressed on mouse podocyte and mediated podocyte lipid uptake. Compared with control group, Ox-LDL increased cell cholesterol accumulation, and up-regulated SR-A expression along with inhibited expression of PTEN and nephrin (P＜0.05), which were correlate with dose and exposure time of Ox-LDL. Expression of PTEN significantly inhibits the expression level of SR-A and lipid uptake induced by Ox-LDL (P＜0.05), thereby decreasing cell cholesterol accumulation, but up-regulating nephrin level (P＜0.05). However, down-regulation of PTEN could cause opposite effect. Conclusion Ox-LDL up-regulates SR-A through decreasing the expression of PTEN, and contributes to podocyte injury.     

Early autophagy activation inhibits podocytes from apoptosis induced by aldosterone

Objective To explore the protection of early autophagy activation on podocyte injury induced by aldosterone. Methods In vitro cultured mouse podocyte clones (MPC5) were treated with aldosterone for 6, 12, 24, 48 h respectively. Apoptosis of podocytes was detected by Annexin V combined with flow cytometry. After 24 h treatment with aldosterone, the existence of apoptotic body and autophagosome was observed by electron microscopy. The protein expressions of LC3, caspase?3 and nephrin were examined by Western blotting. The mRNA expression of Beclin?1 was detected by real?time PCR. Results The induction of apoptosis and autophagy by aldosterone in podocytes was in time?dependent mannner. After 24 h treatment with aldosterone, the apoptosis was increased by 26.5% (P＜0.05) and the expression of nephrin was decreased by 28.0% (P＜0.05) compared to control group. Aldosterone remarkably induced the expression of Beclin?1 at 6 h and promoted the transformation of LC3?Ⅰto LC3?Ⅱ at 12 h (P＜0.05). Compared to simple aldosterone treatment, the apoptosis rate of podocyte was increased by 39.0%（P＜0.05）and the expression of nephrin was declined by 19.5%（P＜0.05) after 3?methyladenine (3?MA) pre?treatment. Conclusions Aldosterone can induce autophagy and apoptosis in podocytes. Autophagy occurs earlier (12 h) than apoptosis (24 h). The occurrence of autophagy can inhibit the apoptosis,so the autophagy pathway may be a new research topic of glomerular disease treatment.     

Protective effect ofACTH4-10 on adriamycin-induced podocyte injury

Objective To observe the influence of adrenocorticotropic hormone (ACTH4-10) in the changes of podocyte proliferation, apoptosis and expression of nephrin and podocin on adriamycin(ADR) -induced podocyte injury and investigate the protective effect ofACTH4-10. Methods All podocytes were randomly divided into following groups: normal control, ADR-induced group andACTH4-10 intervention group (low, middle and high concentration). Normal control group was not treated, ADR-induced group was induced to set the model of podocyte injury by ADR (1 μmol/L) for 24 hours andACTH4-10 intervention groups were intervened by 1 μg/L, 10 μg/L and 100 μg/LACTH4-10 for 1 hours respectively, prior to setting the model of podocyte injury. Cell counting kit (CCK-8) was used to detect the multiplication of podocytes and TUNEL apoptosis detection kit was used to detect podocyte apoptosis. Real-time PCR and Western blotting were used to examine the expression of nephrin and podocin. Results Compared with control group, podocyte proliferation and expression of nephrin and podocin was decreased significantly in ADR-induced group (P＜0.05), meanwhile podocyte apoptosis was increased obviously (38.14% vs 5.12%). Compared with ADR-induced group, podocyte proliferation and expression of nephrin and podocin was increased generally with concentration ofACTH4-10. Although podocyte apoptosis rates (20.45%, 17.39%, 11.02%) were increased inACTH4-10 intervention group (low, middle and high concentration) while comparing with normal control group, podocyte apoptosis decreased obviously while comparing with ADR-induced group. ConclusionsACTH4-10 can stabilize the expression of nephrin and podocin on slid diaphragm, and has the protective effect on podocyte injury induced by ADR, while the effect depends on the concentration ofACTH4-10.     

Ursolic acid inhibits high glucose-induced epithelial mesenchymal transition of podocyte by mediating Wnt/β-catenin signaling pathway

Objective To observe the epithelial mesenchymal transition (EMT) of podocyte induced by high glucose, and to explore the potential protective mechanism of ursolic acid (UA). Methods The podocytes cultured in vitro were divided into four groups: normal group (glucose 5.5 mmol/L), mannitol group (glucose 5.5 mmol/L+mannitol 19.5 mmol/L), high glucose group (glucose 25 mmol/L) and UA group (glucose 25 mmol/L+UA 5 μmol/L). Podocyte morphology changes were observed by inverted phase contract microscope. The expression of zonula occludens-1 (ZO-1) and α-smooth muscle actin (α-SMA) were detected by immunofluorescence. The expressions of β-catenin and glycogen synthesis kinase-3β (GSK3β) were detected by Western blotting. The expressions of Wnt1, Wnt3a, Wnt5a, Wnt5b and GSK3β were detected by real-time PCR. Results Podocytes showed irregular arborization shape in normal glucose and transited to longer cobblestone-like shape as mesenchyme cell by high glucose culture. Compared with normal group, the expression of ZO-1 protein was down-regulated and the expression of α-SMA was up-regulated by high glucose culture (P＜0.05). The expression of Wnt5a mRNA was down-regulated; β-catenin mRNA and protein were up-regulated (P＜0.05); and GSK3β protein was down-regulated by high glucose culture (P＜0.05). Compared with high glucose group, ursolic acid inhibited podocyte EMT, up-regulated the expression of ZO-1 protein, Wnt5a mRNA, GSK3β (P＜0.05), and down-regulated the expressions of α-SMA protein, β-catenin mRNA and protein (P＜0.05). Conclusion Ursolic acid attenuates high glucose induced epithelial mesenchymal transition of podocyte by inhibiting Wnt/β-catenin signaling pathway.     

Effect of aldosterone receptor antagonist on obesity-related glomerulonephropathy

Objective To examine whether aldosterone contribute to obesity related glomerular disease. Methods C57BL/6J mice were randomly divided into three groups: a control group (low-fat-diet, n=10), a model group (high-fat-diet, n=10) and a intervention group (high-fat-diet, n=12). After 8 weeks intervention group were treated with a mineralocorticoid receptor antagonist, spirolactone (SPL).The physicochemical indexes and the renal pathology of the three groups were all detected. The mRNA and protein expressions of podocyte marker protein were determined by real-time PCR and Western blotting, respectively. Results Compared with the control group, body weight, kidney weight, Lee’s index, fat index, blood cholesterol, blood triglyceride, creatinine clearance rate, urinary protein excretion, glomerular average diameter, glomerular foot process average width were significantly up-regulated (P＜0.05); The mRNA and protein expression of nephrin, podocin, podoplanin and podocalyxin were significantly down-regulated in model group (P＜0.05). Meanwhile, these changes were attenuated by SPL. Conclusion Aldosterone can participate in the process of obesity- related renal injury, and these can be attenuated by mineralocorticoid receptor antagonist, spirolactone. This gives us preliminary clues to treat ORG.     

Role of autophagy in high glucose-induced podocyte lipid droplet accumulation

Objective To investigate the role of autophagy in high glucose-induced podocyte lipid droplet metabolism. Methods (1) Cultured, conditionally immortalized human podocytes (HPC) were divided into normal control group, high glucose group and mannitol group. Oil red O staining and oil red O staining extraction assay was used to observe the degree of lipid accumulation; Protein level of SREBP-1 was analyzed by Western blotting. (2) HPC were cultured and divided into normal control group, high glucose group, high glucose+3-methyladenine (3-MA) group, and mannitol group. Acridine orange staining was used to observe the formation of autophagosomes. Western blotting was used to detect the protein levels of beclin-1 and LC3-II/LC3-I. Oil red O staining and oil red O staining extraction assay was used to observe the degree of lipid accumulation; Western blotting was used to analyze the expression of SREBP-1. Results (1) Compared with the normal control group, the lipid accumulation in the high glucose group was increased and the lipid metabolism related molecule SREBP-1 was up-regulated (P＜0.05); There was no significant difference between the normal control group and the mannitol group in lipid accumulation (P＞0.05). (2) Compared with the normal group, the number of autophagosomes was increased and autophagy-related proteins beclin-1 and LC3-II/LC3-I were up-regulated in high glucose group (all P＜0.05). After intervened with 3-methyladenine, a significant decrease in autophagosomes was observed; Protein levels of autophagy-related proteins beclin-1 and LC3-II/LC3-I were decreased (all P＜0.05); The lipid droplets in the high glucose+3-MA group was decreased and lipid metabolism related molecule SREBP-1 was down-regulated (all P＜0.05). Conclusion Autophagy may be involved in the process of high-glucose-induced podocyte lipid accumulation by affecting SREBP-1 expression, and inhibition of autophagy can alleviate the high-glucose-induced podocyte lipid accumulation.     

Effects of bone marrow-derived mesenchymal stem cells on glomerular podocyte injured by lipopolysaccharide

Objective To observe the effects of bone marrow-derived mesenchymal stem cells (BMSC) on glomerular podocyte injured by lipopolysaccharide (LPS) and the expression of related protein. Methods Podocytes are divided into control group, BMSC group, LPS group and LPS plus BMSC group. After 24 hours of intervention, observing each experimental group podocyte form under inverted phase contrast microscope;detecting the expressions of mRNA and protein of nephrin, CD2AP, synaptopodin, and TRPC6 by RT-PCR and Western-blot. Results Compared with control group, expressions of nephrin, CD2AP, and synaptopodin in LPS group decreased (P＜0.05) while that of TRPC6 increased (P＜0.05); compared with LPS group, expressions of nephrin, CD2AP, and synaptopodin in LPS+MSC group increased (P＜0.05) while that of TRPC6 decreased (P＜0.05). Conclusion BMSC may relieve LPS-induced podocyte injury.     

雷帕霉素通过调节mTOR-ULK1信号通路减轻高糖诱导的足细胞损伤

目的探讨雷帕霉素对高糖环境下足细胞自噬和损伤作用的机制。 方法体外培养永生化小鼠肾小球足细胞(mouse podocyte cell 5,MPC5)并进行分组：甘露醇等渗组(mannitol isotonic group,MG组)、高糖组( high glucose group,HG组)、雷帕霉素组(rapamycin group,RG组)以及自噬相关蛋白5-siRNA组(SiG组)。PCR和Western印迹检测足细胞标志Synaptopodin、自噬相关的ULK1以及mTOR通路相关蛋白p70S6K的表达。 结果与MG组相比,HG组的Synaptopodin表达降低,自噬活性降低,p-ULK1以及p70S6K表达明显升高。与HG组相比,RG组的Synaptopodin表达升高,自噬活性较高,p-ULK1以及p70S6K表达较低。SiG组表现出与HG组相似的变化趋势。 结论雷帕霉素可能通过mTOR-ULK1信号通路调节足细胞内自噬反应、减轻高糖环境引起的足细胞损伤。     

Intra-renal and urinary mRNA expression of podocyte-associated molecules for the estimation of glomerular podocyte loss

Background: Podocyte loss plays an important role in the pathogenesis of diabetic nephropathy, but counting the number of glomerular podocyte in renal biopsy specimen is a labor-intensive task. We study whether intra-renal and urinary messenger RNA expression of podocyte-associated molecules could be used to estimate glomerular podocyte number in patients with diabetic nephropathy. Method: We studied 21 consecutive patients with biopsy-proven diabetic nephropathy. The intra-renal and urinary mRNA expression of nephrin, podocin, and synaptopodin were measured by real-time quantitative polymerase chain reaction. Podocyte number was determined in micro-dissected glomerulus. The degree of histological scarring was quantified by morphometric analysis. Results: Glomerular podocyte number correlated with intra-renal expression of nephrin (r = 0.510, p = 0.044), podocin (r = 0.605, p = 0.013), and synaptopodin (r = 0.480, p = 0.060). Glomerular podocyte number also significantly correlated with urinary expression of synaptopodin (r = 0.595, p = 0.019) but not other targets. Baseline renal function correlated with intra-renal expression of nephrin (r = 0.617, p = 0.005), synaptopodin (r = 0.474, p = 0.040), and podocin (r = 0.443, p = 0.057). The degree of tubulointerstitial scarring also inversely correlated with intra-renal expression of nephrin (r = ?0.462, p = 0.047), podocin (r = ?0.458, p = 0.049), and synaptopodin (r = ?0.500, p = 0.029) but not with urinary gene expression. Conclusion: Intra-renal expression of podocyte-associated molecules correlated with glomerular podocyte number, renal function, and tubulointerstitial scarring. The results suggest that intra-renal, but not urinary expression of podocyte-associated molecules, might be used to assess the degree of podocyte loss in diabetic nephropathy.     

Role of ROCK1 in the podocyte injury induced by oxidized low-density lipoprotein

Objective To explore the role of ROCK1 in oxidized low-density lipoprotein (ox-LDL) induced podocyte injury and its possible mechanism. Methods The conditionally immortalized mouse podocyte cells were cultured in vitro and exposed to 20 μg/ml ox-LDL for 24 h. Western blotting was used to analyze the expression level of p-MYPT, nephrin, LC3-Ⅱ, p62, p-ULK1 in groups of control, ox-LDL, ROCK1 siRNA with ox-LDL, wtROCK1 with ox-LDL. Podocytes were incubated with DiI labeled ox-LDL for 4 h and fluorescence microscope was used to analyze lipid distribution. Results Compared with control group, ox-LDL increased cell cholesterol accumulation, activated ROCK along with decreased nephrin, LC3-Ⅱ(P＜0.05), and increased p62, and p-ULK1 expression (P＜0.05). Over-expression of ROCK1 significantly decreased the expression of nephrin and LC3-Ⅱ, but up-regulated the levels of p62, p-ULK1 and cell cholesterol accumulation in ox-LDL stimulated podocytes (P＜0.05). In contrast, Inhibition of ROCK1 protected podocyte by improved lipophagy. Conclusion ROCK1 mediated disfunction of lipophagy contributes to the ox-LDL induced podocyte injury.     

Autophagy alleviate podocytes injury induced by contrast media via oxidative stress

Objective To evaluate the effects of autophagy on oxidative stress induced by contrast media in podocytes. Methods The differentiated mouse podocytes were exposed to contrast media (Iopromide, 50 mg/L)、rapamycin (Rap, autophagy enhancer, 1 ng/L), 3-methyladenine (3-MA, autophagy inhibitor, 2 mmol/L) for 2 hours. The expression of autophagy protein LC3-Ⅱand Beclin-1 as well as oxidative stress-related proteins Catalase, MnSOD were detected by Western blot. The formations of autophagy were observed by MDC staining, and the levels of reactive oxygen species (ROS) by CM-H2DCFDA staining. Cell activity was evaluated by CCK8 assay. Results Both the levels of oxidative stress and autophagy in podocytes increased when stimulated by contrast media, the expression of LC3-Ⅱand Beclin-1 were enhanced, Catalase and MnSOD were inhibited (all P＜0.05). Rapamycin increased the expression of Catalase, MnSOD and cell activity of podocytes, reduced the generation of ROS (all P＜0.05), but in Rap group, cell activity showed no significant difference (P＞0.05). 3-MA decreased the expression of Catalase、 MnSOD and inhibited the cell activity of podocyte, increased the generation of ROS (all P＜0.05). Conclusion Autophagy protects podocyte from contrast media by the means of reducing oxidative stress.     

Sustained increase of microRNA-21 abundance drives aristolochic acid-induced acute kidney injury to renal tubulointerstitial fibrosis

Objective To investigate the role of increased microRNA-21 (miR-21) in the development of renal tubulointerstitial fibrosis secondary to aristolochic acid induced acute kidney injury. Methods C57BL/6J male mice were intraperitoneally injected with aristolochic acid at a dose of 10 mg/kg. Blood samples and kidneys were harvested at day 1, 3, 7, 14, 28 after aristolochic acid treatment. To assess the role of miR-21 in aristolochic acid induced acute kidney injury to chronic kidney disease progression, mice were intravenously injected with anti-miR-21 or anti-scramble (10 mg/kg) at 1 h before aristolochic acid dosing, as well as d5 and d10 after aristolochic acid dosing. Results Increased serum creatinine and severe kidney injury were found at d3 after aristolochic acid treatment. Renal tubulointerstitial fibrosis was developed at d14 after aristolochic acid treatment. Protein expression of α-SMA, vimentin and collagen I were significantly up-regulated at d7 and peaked at d14 (P＜0.01), while protein abundance of E-Cadherin decreased at d14 and lasted until d28 (P＜0.01). The abundance of miR-21 increased at d7 after aristolochic acid dosing, peaking at d14 and thereafter maintaining at a high level. Anti-miR-21 intervention relieved renal injury with reduced serum creatinine (P＜0.05) and attenuation of renal tubulointerstitial fibrosis. Besides, the protein expression of α-SMA, vimentin, and collagen I/IV was all down-regulated after anti-miR-21 treatment (P＜0.05). PTEN was up-regulated and the ratio of its downstream genes p-AKT/AKT was decreased. (P＜0.05) Conclusions A single high dose of aristolochic acid leads to acute kidney injury and the development of renal tubulointerstitial fibrosis secondary to AKI. Renal tubulointerstitial fibrosis could be partially reversed by inhibiting miR-21 via PTEN/ p-AKT pathway.     

姜黄素拮抗瘦素损伤小鼠足细胞的实验研究

目的：探讨瘦素对小鼠足细胞的损伤效应,及姜黄素拮抗这一效应的可能.方法：小鼠足细胞分为四组,分别为空白对照组,瘦素刺激组,姜黄素加瘦素组,及姜黄素对照组.mRNA检测采用实时定量PCR方法,蛋白检测采用免疫印迹法.结果：瘦素（15 ng/ml）能显著抑制足细胞nephrin,podocin,podoplanin,podocalyxin表达,与对照组比较,mRNA表达的抑制率分别为31％、28％、33％及29％;蛋白质表达的抑制率分别为26％、30％、24％及32％,P均＜0.05.加入姜黄素（5μmol/L）后,上述足细胞标志蛋白均被上调,与瘦素组比较,mRNA表达分别上调1.25、1.15、1.34及1.20倍;蛋白质表达分别上调1.15、1.31、1.14及1.32,P均＜0.05.瘦素（15 ng/ml）能显著活化Wnt/β-catenin信号通路,与对照组比较,Wnt1、Wnt2b和Wnt6及其下游蛋白β-catenin的mRNA表达分别上调1.54、1.29、1.52及1.25倍,P均＜0.05.β-catenin的蛋白磷酸化水平抑制率为17％,P＜0.05.加入姜黄素（5μmol/L）后,上述信号通路分子均被抑制,与瘦素组比较,Wnt1、Wnt2b和Wnt6及β-catenin的mRNA表达抑制率分别为12％、12％、22％及10％,P＜均0.05.磷酸化的β-catenin上调1.13倍.结论：瘦素能通过Wnt/β-catenin信号通路损伤足细胞,而姜黄素能逆转这一反应.     

Reduced podocin expression in minimal change disease and focal segmental glomerulosclerosis is related to the level of proteinuria

Background

Glomerular podocyte molecules are involved in the pathogenesis of congenital nephrotic syndrome. However, their role in primary nephrotic syndrome is not clear. This study investigated the expression of nephrin, podocin and synaptopodin in primary nephrotic syndrome.

Methods

Eighty-seven patients with primary nephrotic syndrome including minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MN) and membranoproliferative glomerulonephritis Type I (MPGN) were included in the study. Glomerular expression of nephrin, podocin and synaptopodin was studied in renal biopsies by immunofluorescence and immunohistochemistry. Correlation of expression with clinical and biochemical parameters was performed.

Results

The pattern of expression for all podocyte proteins in controls was uniform fine granular along the capillary walls towards the visceral epithelial cell aspect. Glomerular expression of nephrin was present in all renal biopsies and was similar to that in controls. Glomerular synaptopodin expression was seen in all MN and MPGN patients, while it was seen in 74 % (17/23) MCD and 93.5 % (29/31) FSGS. Reduced synaptopodin expression showed no correlation with clinical and biochemical factors. Podocin expression was present in 5/23 MCD (22 %), 3/31 FSGS (9.6 %), 13/17 MN (76.4 %) and 13/16 MPGN (81 %) patients. The reduced expression of podocin significantly correlated with the degree of proteinuria (p = 0.032). No correlation with age, gender and serum creatinine level was observed.

Conclusion

Reduction of glomerular podocin expression found in MCD and FSGS is related to the amount of proteinuria. Our findings suggest that alteration in podocyte phenotype may not be a primary event and may reflect the degree of podocyte injury in primary nephrotic syndrome.     

Triptolide protects podocytes from puromycin aminonucleoside induced injury in vivo and in vitro

Extracts of Tripterygium wilfordii Hook F have been used to treat glomerulonephritis for more than 30 years in China with dramatic antiproteinuric effects. Triptolide, a diterpene triepoxide, is one of the major active components of these extracts. To clarify its antiproteinuric effects we induced podocyte injury by puromycin aminonucleoside. Triptolide effectively reduced the proteinuria induced by puromycin in nephrotic rats without reducing the glomerular filtration rate. The antiproteinuric effect was associated with improvement in the foot process effacement, a decrease in the podocyte injury marker desmin as well as the restoration of nephrin and podocin expression and distribution. In cultured mouse podocytes triptolide pretreatment prevented the puromycin-induced disruption of the actin cytoskeleton and microfilament-associated synaptopodin while protecting nephrin and podocin expression. Triptolide suppressed reactive oxygen species generation and p38 mitogen-activated protein kinase activation while restoring RhoA signaling activity. These results show that triptolide ameliorates puromycin aminonucleoside-mediated podocyte injury in vivo and in vitro.