Benigni Ariela, Zoja Carla, Tomasoni Susanna, Campana Marco, Corna Daniela, Zanchi Cristina, Gagliardini Elena, Garofano Elvira, Rottoli Daniela, Ito Takahito, Remuzzi Giuseppe
Mario Negri Institute for Pharmacological Research, Azienda Ospedaliera, Ospedali Riuniti di Bergamo, Via Gavazzeni 11, Bergamo 24125, Italy, and Osaka University School of Medicine, Suita, Japan.
J Am Soc Nephrol. 2006 Jun;17(6):1624-32. doi: 10.1681/ASN.2005090983. Epub 2006 May 10.
The renoprotective potential of the peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonist pioglitazone was explored in an immune model of progressive nephropathy, passive Heymann nephritis (PHN), compared with that of an angiotensin II receptor antagonist, taken as standard therapy for renoprotection. PHN rats received orally vehicle, pioglitazone (10 mg/kg twice daily), or candesartan (1 mg/kg twice daily) from months 2 to 8. Pioglitazone reduced proteinuria as effectively as candesartan and limited renal functional and structural changes. Kidneys from untreated PHN rats showed lower nephrin mRNA and protein than controls, both restored by pioglitazone. The effect was seen both early and late during the course of the disease. Whether the antiproteinuric effect of pioglitazone could be due to its effect on nephrin gene transcription also was investigated. HK-2 cells were transfected with plasmids that harbor the luciferase gene under portions (2-kb or 325-bp) of human nephrin gene promoter that contain putative peroxisome proliferator-responsive elements (PPRE) and incubated with pioglitazone (10 muM). Transcriptional activity of luciferase gene was highly increased by pioglitazone, with the strongest expression achieved with the 325-bp fragment. Increase in luciferase activity was prevented by bisphenol A diglycidyl ether, a PPAR-gamma synthetic antagonist. Electrophoretic mobility shift assay experiments showed a direct interaction of PPAR/retinoid X receptor heterodimers to PPRE present in the enhancer region of the nephrin promoter. In conclusion, pioglitazone exerts an antiproteinuric effect in immune-mediated glomerulonephritis as angiotensin II receptor antagonist does. Enhancement of nephrin gene transcription through specific PPRE in its promoter discloses a novel mechanism of renoprotection for PPAR-gamma agonists.
在进行性肾病的免疫模型——被动型Heymann肾炎（PHN）中，探讨了过氧化物酶体增殖物激活受体γ（PPAR-γ）激动剂吡格列酮的肾脏保护潜力，并与作为肾脏保护标准疗法的血管紧张素II受体拮抗剂进行了比较。从第2个月到第8个月，PHN大鼠口服赋形剂、吡格列酮（每日两次，每次10 mg/kg）或坎地沙坦（每日两次，每次1 mg/kg）。吡格列酮降低蛋白尿的效果与坎地沙坦相当，并限制了肾功能和结构的改变。未经治疗的PHN大鼠的肾脏中，nephrin mRNA和蛋白水平低于对照组，而吡格列酮可使其恢复。在疾病过程的早期和晚期均观察到了这种效果。还研究了吡格列酮的抗蛋白尿作用是否归因于其对nephrin基因转录的影响。用携带荧光素酶基因的质粒转染HK-2细胞，该质粒位于人nephrin基因启动子的部分区域（2-kb或325-bp），这些区域含有假定的过氧化物酶体增殖物反应元件（PPRE），然后用吡格列酮（10 μM）孵育。吡格列酮可显著提高荧光素酶基因的转录活性，325-bp片段的表达最强。双酚A二缩水甘油醚（一种PPAR-γ合成拮抗剂）可阻止荧光素酶活性的增加。电泳迁移率变动分析实验表明，PPAR/视黄酸X受体异二聚体与nephrin启动子增强子区域中的PPRE直接相互作用。总之，吡格列酮在免疫介导的肾小球肾炎中发挥的抗蛋白尿作用与血管紧张素II受体拮抗剂相同。通过其启动子中的特定PPRE增强nephrin基因转录揭示了PPAR-γ激动剂肾脏保护的新机制。
