Gremlin-mediated decrease in bone morphogenetic protein signaling promotes aristolochic acid-induced epithelial-to-mesenchymal transition (EMT) in HK-2 cells

Ingestion of aristolochic acid (AA) is associated with the development of aristolochic acid nephropathy (AAN), which is characterized by progressive tubulointerstitial fibrosis, chronic renal failure and urothelial cancer. Our previous study showed that bone morphogenetic protein-7 (BMP-7) could attenuate AA-induced epithelial-to-mesenchymal transition (EMT) in human proximal tubule epithelial cells (PTEC). However, how gremlin (a BMP-7 antagonist) antagonizes the BMP-7 action in PTEC remained unsolved. The aim of the current study was to investigate the role of gremlin in AA-induced EMT in PTEC (HK-2 cells). HK-2 cells were treated with AA (10 μmol/L) for periods up to 72 h. Cell viability was determined by tetrazolium dye (MTT) assay. Morphological changes were assessed by phase-contrast microscopy. Markers of EMT, including E-cadherin and α-smooth muscle actin (α-SMA) were detected by indirect immunofluorescence stains. The BMP-7 and gremlin mRNA and protein expression in HK-2 cells were analyzed by quantitative real-time PCR (real-time RT-PCR) and western blotting after exposure to AA. The level of phosphorylated Smad1/5/8, a marker of BMP-7 activity, was also determined by western blot analysis. Cells were transfected with gremlin siRNA to determine the effects of gremlin knockdown on markers of EMT following treatment with AA. Our results indicated that AA-induced EMT was associated with acquisition of fibroblast-like cell shape, loss of E-cadherin, and increases of alpha-SMA and collagen type I. Interestingly, exposure of HK-2 cells to 10 μmol/L AA increased the mRNA and protein expression of gremlin in HK-2 cells. This increase was in parallel with a decrease in BMP-7 expression and a down-regulation of phosphorylated Smad1/5/8 protein levels. Moreover, transfection with siRNA to gremlin was able to recover BMP-7 signaling activity, and attenuate EMT-associated phenotypic changes induced by AA. Together, these observations strongly suggest that gremlin plays a critical role in the modulation of reno-protective action of BMP, and that inhibition of gremlin will be a promising means of developmenting novel treatments for AAN.     

丹酚酸B对肾小管上皮细胞转分化的影响及机制

目的:用转化生长因子(TGF-β1)诱导人肾小管上皮细胞(HK-2)转分化,观察丹酚酸B(SA-B)对HK-2细胞转分化过程的干预作用并初步探讨其机制。方法:TGF-β1(5 ng.mL-1)刺激HK-2细胞,用丹酚酸B(SA-B)(10μmol.L-1)干预;用免疫荧光法检测各组HK-2细胞黏着斑激酶(FAK)、整合素β1(β1-integrin)的表达。结果:TGF-β1成功诱导HK-2转分化;相比空白对照组,SA-B可抑制HK-2转分化,且SA-B可有效降低HK-2细胞FAK及β1-integrin蛋白的表达(P均小于0.05)。结论:SA-B可有效调节人肾小管上皮细胞转分化过程,其机制可能与其能调控HK-2细胞FAK及β1-integrin蛋白的表达有关。     

BMP-7对TGF-β_1诱导人肾小管上皮细胞外基质表达的影响

目的观察骨形态发生蛋白-7(BMP-7)对TGF-β1诱导人近端肾小管上皮细胞(HK-2)细胞外基质(ECM)成分表达的影响,以探讨其延缓肾间质纤维化病变的作用机制。方法将体外培养的HK-2细胞分为空白对照组,3μg.L-1TGF-β1组,BMP-7组,TGF-β1加不同浓度BMP-7组。免疫荧光检测FN的表达;RT-PCR和Western blot分别检测FN、ColⅠα1mRNA及蛋白的表达。结果免疫荧光检测结果显示,3μg.L-1TGF-β1刺激HK-2细胞48h后,FN表达明显增强;加入200μg.L-1BMP-7干预后荧光明显减弱。RT-PCR和Western blot结果显示,TGF-β1刺激HK-2细胞48h后,FN、ColⅠα1mRNA及蛋白表达均明显高于对照组(P<0.01);BMP-7(100～400μg.L-1)可在mRNA及蛋白水平呈剂量依赖性下调TGF-β1诱导的FN、ColⅠα1的表达。结论BMP-7能抑制TGF-β1诱导的HK-2细胞FN、ColⅠα1的合成。表明BMP-7抑制肾小管间质纤维化的进展、改善肾功能的作用,部分是通过抑制肾小管上皮细胞分泌细胞外基质实现的。     

法舒地尔对高糖培养的肾小管上皮细胞转分化的抑制作用

目的探讨法舒地尔对高糖培养人肾小管上皮细胞(HK-2)转分化的影响及可能作用机制。方法人肾小管上皮细胞同时加入葡萄糖60 mmol·L-1和法舒地尔20μmol·L-1。配体结合沉淀法检测葡萄糖60mmol·L-1作用0～24 h后细胞Rho A活性,免疫细胞化学技术检测上皮钙黏素表达,Western印迹法检测α-平滑肌肌动蛋白(α-SMA)的表达,ELISA法检测细胞培养上清液转化生长因子β1(TGF-β1)的含量。结果在一定时间范围内,高糖能刺激细胞Rho A分子活化;与正常对照组比较,葡萄糖60 mmol·L-1培养HK-2细胞72 h后上皮钙黏素表达明显减少(P<0.01),α-SMA表达明显增多(P<0.01),TGF-β1分泌增多(P<0.01),而葡萄糖5.5 mmol·L-1+甘露醇54.5 mmol·L-1高张组无明显差异。法舒地尔20μmol·L-1同步干预后,与高糖组比较,细胞上皮钙黏素表达明显增多〔(0.03±0.01)vs(0.08±0.02),P<0.05〕,α-SMA表达下降(P<0.05),48 h时TGF-β1分泌明显减少〔(128±11)vs(49±5)μg.g-1(P<0.05)〕。结论法舒地尔能抑制高糖培养的肾小管上皮细胞转分化,可能部分通过减少TGF-β1的分泌发挥作用。     

骨化三醇对单侧输尿管梗阻大鼠肾小管上皮细胞转分化影响的研究

目的观察幼年大鼠单侧输尿管梗阻(UUO)肾组织中α-肌动蛋白(α-SMA)、E-钙黏蛋白(E-Cad)、转化生长因子-β1(TGF-β1)、骨形态发生蛋白-7(BMP-7)mRNA的表达,探讨骨化三醇对肾小管上皮细胞转分化(EMT)干预效应及机制。方法 54只雄性SD大鼠随机分为3组:假手术组(A组)、UUO模型组(B组)及UUO模型干预组(C组)各18只,灌胃满3、7、14d取肾。实时荧光定量聚合酶链反应(RT-PCR)法检测各组α-SMA、E-Cad、TGF-β1、BMP-7mRNA表达水平。结果与A组相比,B组E-Cad、BMP-7mRNA表达明显下降(P<0.01),α-SMA、TGF-β1mRNA表达显著增高(P<0.01);C组与B组相比,E-Cad、BMP-7mRNA表达明显上调(P<0.01),α-SMA、TGF-β1mRNA表达明显下降(P<0.01)。结论骨化三醇对UUO模型大鼠肾小管上皮细胞转分化有抑制作用,这种抑制作用可能与下调TGF-β的表达及上调BMP-7的表达有关。     

α-酮戊二酸钠对转化生长因子β_1诱导的HK-2细胞上皮-间充质转分化的影响

目的探讨α-酮戊二酸钠对转化生长因子β1(TGF-β1)诱导的HK-2细胞上皮-间充质转分化(EMT)的影响。方法 TGF-β10.5,2和5μg.L-1分别作用于葡萄糖5和30 mmol.L-1培养的HK-2细胞72 h,通过RT-PCR法检测EMT标志物E-钙黏着糖蛋白和波形蛋白mRNA表达的变化,以选择EMT病变模型的最佳诱导条件。在此基础上,观察α-酮戊二酸钠10,100和500μmol.L-1对HK-2细胞EMT病变及G蛋白偶联受体80(GPR80)mRNA表达的影响。结果①在葡萄糖5和30 mmol.L-1条件下,当TGF-β1为5μg.L-1时,与对照组比较,E-钙黏着糖蛋白mRNA的降低和波形蛋白mRNA的升高最明显(P<0.01),表明HK-2细胞发生了典型的EMT病变;②选择TGF-β15μg.L-1和葡萄糖30 mmol.L-1制备EMT病变模型,同时加入α-酮戊二酸钠100和500μmol.L-1作用72 h,与模型组比较,E-钙黏着糖蛋白mRNA明显升高,波形蛋白mRNA明显降低,GPR80 mRNA表达增加(P<0.01),表明α-酮戊二酸钠可逆转HK-2细胞EMT的发生。结论在葡萄糖5和30 mmol.L-1培养条件下,TGF-β15μg.L-1作用72 h,HK-2细胞可出现典型的EMT病变;α-酮戊二酸钠对该病变具有抑制作用。     

普罗布考对甲基胍诱导纤维化相关因子在HK-2细胞表达的影响

目的研究降脂药普罗布考对小分子尿毒素甲基胍诱导纤维化相关因子在人肾小管上皮细胞表达的影响。方法 HK-2细胞分3组培养,A组（正常对照,不加干预因素）;B组培养基中加入0.5mmol.L-1甲基胍;C组培养基中加入0.5mmol.L-1甲基胍和20μmol.L-1普罗布考。各组细胞培养48h后用免疫细胞化学、RT-PCR检测TGF-β1、CTGF和FN,并用流式细胞仪对以上因子作定量检测,以观察其在HK-2细胞中的表达。结果在甲基胍刺激后,细胞免疫化学染色,HK-2细胞质中着色,显示TGF-β1、CTGF和FN均有表达。正常对照组HK-2细胞质中无着色。测定结果显示甲基胍组TGF-β1、CTGF和FN显著高于正常对照组（P〈0.01）,加入普罗布考后,表达显著下降（P〈0.01）。结论甲基胍能促进纤维化相关因子在肾小管上皮细胞中表达;普罗布考能抑制甲基胍诱导纤维化相关因子在肾小管上皮细胞的表达。     

去甲斑蝥素对TGF—β1诱导的人近端肾小管细胞上皮细胞转分化及信号蛋白Smad2／3表达的影响

目的探讨去甲斑蝥素对体外人源性肾小管细胞株（HK－2）上皮细胞间质转分化（epithelial—mesenchymal transition,EMT）以及信号蛋白Smad2／3的影响。方法体外培养HK2细胞,分为对照组、TGF-β1组和去甲斑蝥素组（NCTD组）。对照组为无血清DMEM培养,TGG-β1组为TGF-β1 5ng·mL^-1诱导,NCTD组为不同浓度NCTD（0．5、1．0、2．5μg·mL^-1）与TGF-β1（5ng·mL^-1）共同作用,各组作用时间48h。使用半定量RT-PCR法检测α-平滑肌肌动蛋白（α-SMA）、上皮性钙黏附蛋白（Ecadherin）与Smad2、Smad3mRNA表达;采用Western blot检测α-SMA、E-cadherin、Smad2／3、p-Smad2／3蛋白质表达。结果与对照组相比,TGF-β1组α—SMAmRNA及其蛋白表达明显上调（Pd0．05）,E-cadherin mRNA及其蛋白表达显著下调（P〈0．05）;与TGF-β1组相比,NCTD干预组α—SMAmRNA及其蛋白表达明显下调（P〈0．05）,而E-cadherin mRNA及其蛋白表达显著上调（P〈0．05）,且均呈剂量依赖性。与对照组相比,TGF-β1组Smad2、Smad3rnRNA和Smad2／3、p-Smad2／3蛋白表达上调（P〈0．05）;与TGF-β1组比较,NCTD干预组Smad2、Smad3mRNA和Smad2／3、p-Smad2／3蛋白表达下调（P〈0．05）,具有剂量依赖关系。结论去甲斑蝥素具有抑制肾小管上皮细胞EMT的作用,该作用可能与其下调信号蛋白Smad2／3的表达有关。     

三七皂苷对肾小管上皮细胞内TGF-β_1、纤维连接蛋白的影响

目的探讨三七皂苷干预肾小管间质损害的效果及机制。方法通过体外培养人类近端肾小管上皮细胞,用三七皂苷等干预后,采用ELISA法检测纤维连接蛋白和转化生长因子-β1。结果三七皂苷尤其是三七皂苷联合缬沙坦能抑制纤维连接蛋白和转化生长因子-β1的分泌。结论三七皂苷尤其是联合血管紧张受体拮抗剂可通过抑制FN、TGF-β1的表达,从而抑制细胞外基质的形成,并进一步减轻肾间质的病理性损伤,有效的防治肾间质纤维化的发生。     

慢性马兜铃酸肾病患者血清TGF-β1、BMP-7的改变

目的：探讨慢性马兜铃酸肾病（CAAN）患者血清转化生长因子-β1（TGF-β1）、骨形态发生蛋白-7（BMP-7）的变化及临床意义。方法：采用ELISA法测定30例CAAN患者血清TGF-β1及BMP-7水平,并用20例正常健康人作对照。结果：与对照组相比病例组TGF-β1明显增高（P〈0.05）,BMP-7明显降低（P〈0.05）。TGF-β1与BMP-7呈负相关（r=-0.379,P〈0.05）。结论：TGF-β1、BMP-7二者的表达水平及其相互间调节作用是慢性马兜铃酸肾病发病机制中的重要环节。     

人参皂甙Rg1对TGF-β1诱导的肾小管上皮细胞增殖及细胞外基质的影响

目的:观察人参皂甙Rg1对转化生长因子-β1诱导的肾小管上皮细胞增殖及细胞外基质的影响.方法:MTT法测细胞增殖情况.ELISA法测定培养细胞上清液中Col-Ⅰ,Col-Ⅲ和FN的含量.结果:在10～40 ng/mL浓度范围内时间、剂量依赖性的促进肾小管上皮细胞增殖,减少转化生长因子-β1诱导的肾小管上皮细胞对Col-Ⅰ、Col-Ⅲ、FN的分泌.结论:G-Rg1能够促进TGF-β1诱导下的肾小管上皮细胞的增殖,可能与抑制ECM的分泌有关.     

全反式维甲酸对糖尿病大鼠肾脏组织BMP-7表达及细胞外基质代谢的影响

目的探讨全反式维甲酸（atRA）对糖尿病大鼠肾脏组织骨形成蛋白-7（BMP-7）、转化生长因子-β1（TGF-β1）表达和细胞外基质（E（M）Ⅳ、Ⅲ型胶原代谢的影响。方法随机选择24只舍SD大鼠制作糖尿病模型,其中12只入糖尿病模型（DM）组,另12只入糖尿病模型＋atRA（DM＋atRA）组,此外再随机选择12只正常大鼠作为空白对照（NC）组。分别于第8、12周末各组处死6只大鼠,通过光镜、电镜观察各组大鼠肾脏病理结果;通过免疫组织化学方法观察BMP-7,TGF-β1,Ⅳ、Ⅲ型胶原表达,并进行半定量分析;通过实时荧光定量PCR方法对TGF-β1 mRNA、BMP-7mRNA,进行相对定量分析。结果DM＋atRA组大鼠肾组织BMP-7表达较同时期DM组增加（P〈0.01）,主要表达于大鼠肾小管上皮细胞,而TGF-β1表达较同时期DM组减少（P〈0．01）：且DM＋atRA组大鼠肾组织ECM重要成分Ⅳ、Ⅲ型胶原表达与DM组相比较显著减少（P〈0．01）。同时观察到BMP-7蛋白与Ⅳ型胶原蛋白表达呈负相关（r=-0．75,P〈0．01）,与Ⅲ型胶原蛋白表达呈负相关（r=-0．71,P〈0．01）,与TGF-β1蛋白表达呈负相关（r=-0．86,P〈O．01）。荧光定量PCR结果表明,DM＋atRA组BMP-7mRNA水平升高,TGF-β1 mRNA水平下降,且两者星显著负相关（r=-0．83,P〈0．01）。结论atRA能减轻糖尿病大鼠肾脏病理损伤,延缓肾脏纤维化,这一防治作用可能与其增加BMP-7表达,下调TGF-β1表达从而减少肾组织ECM沉积有关。     

Hirudin improves renal interstitial fibrosis by reducing renal tubule injury and inflammation in unilateral ureteral obstruction (UUO) mice

Renal interstitial fibrosis (RIF) often occurs in many chronic kidney diseases (CKD). Hirudin now is applied to treat fibrosis in some organs. In this study, we verified the treatment effects of hirudin on RIF in vivo and in vitro with the underlying mechanism. The RIF in vivo was the unilateral ureteral obstruction (UUO) model and RIF in vitro was the renal tubular epithelial cells induced by TGF-β. The renal pathological changes and renal fibrosis were observed by hematoxylin and eosin (H&E) staining and Masson staining. The α-SMA in renal tissues was detected by immunohistochemistry. The inflammatory factors were analyzed by the ELISA assay. The cell apoptosis was observed by TUNEL assay. The related proteins of fibrosis, epithelial-mesenchymal transition (EMT) and apoptosis were assessed by western blot analysis. The experimental data demonstrated that hirudin decreased fibrosis, EMT, inflammation and cell apoptosis in renal tissues of UUO rats and TGF-β-induced renal tubular epithelial cells. Furthermore, hirudin also reduced the expression of collgen-I, FN, α-SMA, N-cad, slug, E-cad, IL-1β, IL-6 and TNF-α in mice serum and TGF-β-induced renal tubular epithelial cells. The apoptosis related proteins (pro-caspase3, pro-caspase9, bcl2 and bax) expression was also down-regulated in renal tissues of UUO rats. In conclusion, hirudin depressed the fibrosis in renal tissues and renal tubular epithelial cells by inhibiting the inflammation, regulating the related proteins of fibrosis and ETM and decreasing the apoptosis of renal tubular epithelial cells. These findings may offer an effective treatment method for RIF.     

曲格列酮对转化生长因子-β_1诱导的HK-2细胞纤连蛋白和胶原Ⅰ型基因表达的影响

目的观察曲格列酮对转化生长因子-β1(TGF-β1)诱导的人肾近曲小管上皮细胞(HK-2)细胞外基质纤连蛋白和胶原Ⅰ型的影响,探讨曲格列酮抗肾间质纤维化的潜在作用。方法将曲格列酮0,0.25,0.5,1,2.5,5和10μmol.L-1预处理HK-2细胞2h,随后加入TGF-β15mg.L-1作用24h,利用乳酸脱氢酶(LDH)释放实验检测曲格列酮对HK-2细胞的毒性作用;曲格列酮0,1,2.5,5和10μmol.L-1预处理HK-2细胞2h,再加入TGF-β15mg.L-1作用24h,通过实时荧光定量PCR检测HK-2细胞外基质主要成分胶原Ⅰ型mRNA和纤连蛋白mRNA表达。结果曲格列酮0.25～5μmol.L-1对HK-2细胞膜完整性无影响,LDH的释放与正常对照组无明显差异,曲格列酮10μmol.L-1组LDH释放率为(10.7±5.3)%,明显高于正常对照组(P<0.01)。与正常对照组相比,曲格列酮1,2.5,5和10μmol.L-1单独作用并没有增加HK-2细胞外基质中胶原Ⅰ型纤维和纤连蛋白的表达,而TGF-β1刺激下胶原Ⅰ型纤维和纤连蛋白表达明显上调,曲格列酮提前干预下纤连蛋白mRNA及胶原Ⅰ型mRNA表达下降,曲格列酮2.5,5和10μmo.lL-1可显著下调纤连蛋白mRNA表达(P<0.05,P<0.01);曲格列酮5和10μmol.L-1可显著下调胶原Ⅰ型mRNA表达(P<0.05)。结论曲格列酮可能具有拮抗肾间质纤维化的潜在作用,其作用机制可能与抑制HK-2细胞纤连蛋白和胶原Ⅰ型纤维的增加有关。     

Ganoderic acid hinders renal fibrosis via suppressing TGF-β/Smad and MAPK signaling pathways

OBJECTIVE To investigatethe anti-renal fibrotic effect of Ganoderic acid(GA) and the related mechanisms in vivo and in vitro. METHODS We investigated whether GA could hinder renal fibrosis and the related mechanisms in a unilateral ureteral obstruction(UUO) mouse model and TGF-β1-stimulated HK-2 cells model. The C57 mice were randomly devided into sham group, sham with GA administration group, UUO group and UUO with GA treatment group. After UUO surgery,the mice were treated with GA(3.125, 12.5 and 50 mg·kg~(-1) per day, ip) for 14 d. Then the mice were sacrificed for collecting blood and kidneys. The kidney functions were revealed by blood urea nitrogen and serum creatinine.The fibrosis and tubules injury levels were detected by Masson staining and HE staining. The epithelial-mesenchymal transition(EMT) level was detected by Western blotting and immunohistochemical staining. The changes of related signaling pathways and underlying mechanisms were demonstrated by Western blotting. The cell model was adopted to identify the potent inhibitor of renal fibrosis. RESULTS After 14 d treatment, GA dosedependently attenuated UUO-induced tubular injury and renal fibrosis; GA(50 mg·kg~(-1)) significantly ameliorated renal disfunction during fibrosis progression. We further revealed that GA treatment significantly decreased the expression of mesenchymal cell markers alpha-smooth muscle actin(α-SMA) and vimentin, and up-regulated E-cadherin expression in the kidney, suggesting the suppression of tubular EMT. Further study showed that GA downregulated both TGF-β/Smad and MAPK(ERK,JNK, P38) signaling pathways both in vivo and in vitro.GA-A, a GA monomer, was identified as a potent inhibitor on renal fibrosis in TGF-β1-stimulated HK-2 cell model.CONCLUSION GA inhibits renal interstitial fibrosis induced by UUO, mostly by suppressing EMT progression and inhibiting TGF-β/Smad and MAPK signaling pathways. In conclusion, our results suggest that GA and its purified monomer GA-A might be developed as a potential therapeutic agent in the treatment of renal fibrosis.     

雷公藤多苷对高糖诱导人肾小管上皮细胞凋亡及CXCL10/CXCR3轴的影响

目的 探讨雷公藤多苷（TG）对高糖诱导人肾小管上皮细胞HK-2凋亡及CXC趋化因子配体10(CXCL10)/CXC趋化因子受体3(CXCR3)轴的影响。方法 体外培养人肾小管上皮细胞HK-2,并分为对照组（含5.5 mmol/L葡萄糖培养基）、高糖组（含25 mmol/L葡萄糖培养基）和12.5、25、50 mg/L TG组（分别用12.5、25、50 mg/L的TG和25 mmol/L葡萄糖培养基）。四甲基偶氮唑盐比色法检测HK-2细胞活力;流式细胞术检测HK-2细胞凋亡情况;2’,7’-二氯二氢荧光素二乙酸酯法检测HK-2细胞活性氧（ROS）水平;黄嘌呤氧化酶法检测HK-2细胞超氧化物歧化酶（SOD）水平;酶联免疫吸附试验检测HK-2细胞炎性因子肿瘤坏死因子-α(TNF-α)、转化生长因子-β1(TGF-β1)水平;蛋白免疫印迹法检测HK-2细胞凋亡蛋白[胱天蛋白酶（Caspase）-3、Caspase-9]以及CXCL10、CXCR3蛋白表达。结果 与对照组比较,高糖组HK-2细胞活力、SOD水平显著降低,凋亡率、ROS、TNF-α、TGF-β1水平及Caspase-3、Casp...     

红景天苷对转化生长因子-β1诱导人肾小管上皮细胞逆向分化的影响

目的：阐释红景天苷对转化生长因子-β1（TGF-β1）诱导人肾小管上皮细胞（HKC）表型转分化的效应,探讨其对I型（colⅠ）和Ⅲ型（ColⅢ）胶原蛋白表达的影响。方法：体外培养HKC,应用不同浓度红景天苷处理经TGF-β1诱导活化的HKC细胞,显微镜观察细胞形态改变,免疫组化法检测角化蛋白-18和α-平滑肌肌动蛋白（α-SMA）的表达：应用酶联免疫吸附法（ELISA）检测ColⅠ型和ColⅢ型胶原蛋白表达。结果：HKC细胞经过TGF-β1诱导,细胞角化蛋白．18表达明显下调,α-SMA、ColⅠ、ColⅢ型胶原表达明显上调,与空白对照组比较,差异有统计学意义（P〈0．05）。经红景天苷干预后,其表达有所下降,与TGF-β1诱导组比较,差异有统计学意义（P〈0．05）。结论：红景天苷可抑制TGF-β1诱导的HKC表型转分化,同时可以抑制肾小管上皮细胞外基质成分ColⅠ、ColⅢ型胶原的合成,在一定程度上具有阻止肾小管间质纤维化的作用。     

Cyclophilin D Promotes Acute,but Not Chronic,Kidney Injury in a Mouse Model of Aristolochic Acid Toxicity

The plant-derived toxin, aristolochic acid (AA), is the cause of Chinese Herb Nephropathy and Balkan Nephropathy. Ingestion of high dose AA induces acute kidney injury, while chronic low dose ingestion leads to progressive kidney disease. Ingested AA is taken up by tubular epithelial cells of the kidney, leading to DNA damage and cell death. Cyclophilin D (CypD) participates in mitochondrial-dependent cell death, but whether this mechanism operates in acute or chronic AA-induced kidney injury is unknown. We addressed this question by exposing CypD-/- and wild type (WT) mice to acute high dose, or chronic low dose, AA. Administration of 5 mg/kg AA to WT mice induced acute kidney injury 3 days later, characterised by loss of kidney function, tubular cell damage and death, and neutrophil infiltration. All of these parameters were significantly reduced in CypD-/- mice. Chronic low dose (2 mg/kg AA) administration in WT mice resulted in chronic kidney disease with impaired renal function and renal fibrosis by day 28. However, CypD-/- mice were not protected from AA-induced chronic kidney disease. In conclusion, CypD facilitates AA-induced acute kidney damage, but CypD does not contribute to the transition of acute kidney injury to chronic kidney disease during ongoing AA exposure.     

New aristolochic acid, aristololactam and renal cytotoxic constituents from the stem and leaves of Aristolochia contorta

Two novel phenanthrene derivatives, aristololactam IVa (1) and 9-hydroxy aristolochic acid I (2) were isolated from the stem and leaves of Anstolochia contorta Bunge, together with 17 known compounds (3-19). The structures of these compounds were determined by spectroscopic analysis. The phenanthrenes obtained were tested for cytotoxicity against renal proximal tubular epithelial cell line (HK-2). Aristololactam IVa and 7-methoxy aristololactam IV were found to have strong cytotoxic activity against HK-2 cells with a potency similar to or even stronger than those of aristolochic acid I and aristololactam I.     

Effect of Sedum sarmentosum Bunge Extract on Aristolochic Acid– Induced Renal Tubular Epithelial Cell Injury

Aristolochic acid (AA) is known as a potent mutagen that induces significant cytotoxic and mutagenic effects on renal tubular epithelial cells. Clinically, the persistent injury of AA results in the infiltration of inflammatory cells, epithelial-to-mesenchymal transition (EMT), and renal tubulointerstitial fibrosis. There are no truly effective pharmaceuticals. In this study, we investigated the potential role of the extract of Sedum sarmentosum Bunge (SSB), a traditional Chinese herbal medicine, on rat tubuloepithelial (NRK-52E) cells after AA injury in vitro. Evidence revealed that AA induced mitochondrial-pathway–mediated cellular apoptosis, accompanied by cell proliferation in a feedback mechanism. Treatment with SSB also induced cells to enter early apoptosis, but inhibited cell proliferation. In cultured NRK-52E cells, AA induced the imbalance of MMP-2/TIMP-2 and promoted EMT and ECM accumulation. SSB treatment significantly alleviated AA-induced NRK-52E cells fibrosis-like appearance, inhibited the induction of EMT, and deposition of ECM. SSB also decreased the activity of the NF-κB signaling pathway, resulting in down-regulated expression of NF-κB–controlled chemokines and pro-inflammatory cytokines, including MCP-1, MIF, and M-CSF, which may regulate the macrophage-mediated inflammatory reaction during renal fibrosis in vivo. Therefore, these findings suggest that SSB exerts protective effects against AA-induced tubular epithelial cells injury through suppressing the synthesis of inflammatory factors, EMT, and ECM production.