血管紧张素Ⅱ受体拮抗剂对慢性肾衰竭大鼠肾小管上皮细胞增殖和转分化的影响

Effect of AngiotensinⅡType-1 Receptor Blocker on Renal Tubulointerstitial Cell Transdifferentiation and Proliferation in 5/6 Nephrectomy Rats

目的:探讨血管紧张素Ⅱ受体拮抗剂(ARB)losartan对慢性肾衰竭(CRF)大鼠肾小管上皮细胞增殖和转分化的影响。方法:Wistar大鼠随机分为假手术(Sham)组、模型(Nx)组、ARB小剂量(ARB15,losartan 15mg·kg-1·d-1灌胃)组、ARB大剂量(ARB150,losartan 150mg·kg-1·d-1灌胃)组。5/6肾切除制作CRF模型。12周后,观察各组肾功能、蛋白尿、肾重/体重(BW)、心脏重量/BW、肾脏病理变化,免疫组化观察肾脏胰岛素样生长因子-1(IGF-1)、α-平滑肌肌动蛋白(α-SMA)、Vimentin表达变化及增殖细胞核抗原(PCNA)阳性细胞数,TUNEL法观察细胞凋亡。结果:(1)Nx组大鼠Scr、BUN、24h尿蛋白定量、肾重/BW、心脏重量/BW均明显高于Sham组(P<0.05);ARB治疗后肾功能明显改善、蛋白尿减少、肾重/BW、心脏重量/BW降低(P<0.05)。(2)Nx组大鼠肾组织有明显的肾小球硬化及肾小管间质损伤,肾小球硬化指数(GSI)及肾小管间质损伤指数(TII)均较Sham组明显增高;ARB治疗后GSI及TII均较Nx组降低(P<0.05)。(3)与Sham组比较,Nx组肾间质IGF-1表达明显增加(P<0.05),ARB可明显减少IGF-1的表达(P<0.05)。(4)Sham组肾组织可见α-SMA表达,肾间质无Vimentin表达;Nx组肾间质Vimentin及α-SMA表达增加(均P<0.05),ARB治疗后较Nx组两者表达减少(P<0.05)。(5)Nx组TUNEL阳性细胞和PCNA阳性细胞均明显增加,ARB治疗对TUNEL阳性细胞无明显影响,但可明显减少PCNA阳性细胞数(P<0.05)。结论:ARB可明显减轻CRF大鼠的肾损伤,该作用与抑制局部IGF-1表达和肾小管上皮细胞转分化以及改变细胞凋亡与增生的平衡有关。

Objective：To assess the effect of losartan, an angiotensin Ⅱ type - 1 receptor blocker （ARB）, on the renal tubulointerstitial cell transdifferentiation and proliferation in chronic renal failure （CRF） rats. Methods：Wistar rats were randomly divided into 4 groups： Sham operation group （sham）, nephrectomy group （Nx）, low - dose （ 15 mg·kg^-1·d^-1 ） ARB treated group （ARB15） and high-dose （150 mg·kg^-1·d^-1） ARB treated group （ARB150）. CRF was induced by 5/6 nephrectomy. Twelve weeks after operation, renal function, proteinuria, renal, heart and body weight were measured and renal pathology was observed. The expressions of insulin- like growth factor- 1 （IGF- 1）, alpha- smooth muscle actin （α- SMA）, Vimentin in tubulointerstitial were assessed by immunohistochemistry. Tubulointerstitial Cell Proliferation was assessed by measuring proliferating cell nuclear antigen （PCNA） and tubulointerstitial cell apoptosis was tested by terminal deoxynucleotidyl transferase （TdT） -mediated dUTP- biotin nick end labeling （TUNEL） essay. Results： （1） Compared with sham ones, Nx rats showed increased serum creatinine （Scr）, BUN, 24 - hour proteinuria, renal weight/body weight and heart weight/body weight （ P 〈 0.05 ）. ARB inhibited the increase of above index （ P 〈 0.05）. （2） Nx rats showed higher glomerular sclerosis index （GSI） and the tubulointerstitial index （TII） than the sham. ARB decreased GSI and TII （P〈0.05）. （3） IGF- 1 strongly expressed in renal interstitium in Nx rats, and was down - regulated by ARB. （4） Alpha - SMA was confined to vascular smooth muscle cell in sham rats, while strongly expressed within interstitium in Nx rats. ARB decreased the expression of α - SMA （ P 〈 0.05 ）. Vimentin strongly expressed in interstitium of Nx rats compared with sham rats and was down- regulated by ARB. Conclusion：ARB markedly ameliorates renal injury in CRF rats. The underlying mechanisms is, at least partly, related to the suppression of local IGF - 1 expression and transdifferetion of tubulointerstitial cell as well as regulation the balance between tubulointerstitial cell proliferation and apoptosis.