肾素血管紧张素系统在晚期糖基化终产物改变肾小球内皮细胞通透性中的作用

【摘要】 目的 探讨晚期糖基化终产物（AGE）对大鼠肾小球内皮细胞（rGEnC）紧密连接的影响及激活细胞内肾素血管紧张素系统（RAS）在其中的作用。 方法 采用原代培养的rGEnC，予不同浓度AGE（20、40、80 mg/L）分别作用6 h、12 h和24 h，采用跨内皮细胞电阻抗和异硫氰酸荧光素标记的牛血清白蛋白滤过率观察通透性的变化；Western印迹检测晚期糖基化终产物受体(RAGE)、紧密连接蛋白[occludin、claudin-5、连接黏附分子A（JAM-A）和闭合小环蛋白1（ZO-1）]和细胞RAS组分[血管紧张素原、肾素和血管紧张素Ⅱ（AngⅡ）1型受体（AT1）]蛋白表达量的变化；免疫荧光技术显示紧密连接的完整性；紫外光法和酶免疫分析技术测定细胞内外血管紧张素转化酶（ACE）活性及AngⅡ水平。 结果 AGE可引起内皮细胞通透性、RAGE表达量、ACE活性、AngⅡ浓度和AT1表达量的升高，occludin、claudin-5和JAM-A表达量的下降。加入抗RAGE抗体（100 mg/L）预处理后，上述AGE作用被阻断。AGE可引起上述紧密连接蛋白在细胞连接处的中断。予卡托普利（1 mmol/L）或缬沙坦（10 μmol/L）预处理可部分阻断AGE上述效应。 结论 AGE可通过上调RAGE表达，激活细胞内肾素血管紧张素系统，破坏肾小球内皮细胞紧密连接，导致其通透性的升高。

Role of renin-angiotensin system in advanced glycation end products-induced changes of permeability in rat glomerular endothelial cells

Objective To investigate the effect of advanced glycation end products (AGEs) on the disruption of tight junctions in rat glomerular endothelial cells (rGEnCs) and the role of renin-angiotensin system (RAS) in this pathological procedure.Methods Primary cultured rGEnCs were incubated with AGEs at concentrations of 20 mg/L,40 mg/L and 80 mg/L,for 6 h,12 h and 24 h respectively.The cells were treated with captopril (1 mmol/L) or valsartan (10 μ mol/L)to block RAS.The endothelial permeability was investigated by transendothelial electrical resistance and the flux of fluorescein isothiocyanate-conjugated bovine serum albumin.The expression of AGEs receptor (RAGE),tight junction proteins [occludin,claudin-5,junctional adhesion molecules A (JAM-A) and zona occludens-1 (ZO-1)]and RAS components [angiotensinogen,renin and angiotensin Ⅱ type 1 receptor (AT1)]were detected by Western blotting.Immunofluorescence was used to demonstrate the disruptions of the tight junction proteins.The activity of angiotensin converting enzyme (ACE) was evaluated by UV spectrophotometry.Angiotensin Ⅱ (Ang Ⅱ ) was measured by enzyme immunoassay.Results The monolayer permeability,the expression of RAGE,the activity of ACE,the concentration of Ang Ⅱ and the expression of AT1 of rGEnCs were increased after induced by AGEs.Meanwhile,AGEs decreased the expression of occludin,claudin5 and JAM-A and induced disruption of tight junction proteins.Pretreatment with anti-RAGE antibody (100 mg/L),captopril or valsartan could attenuate the detrimental effect of AGEs.Conclusion The changes of permeability induced by AGEs in glomerular endothelial cells are partly mediated by RAS through RAGE.