单侧输尿管结扎幼鼠肾间质纤维化中周细胞转分化趋势及意义

Transdifferentiational tendency of peritubular pericytes in renal interstitial fibrosis in young rats with unilateral ureteral obstruction

目的：本实验旨在通过观察单侧输尿管结扎（UUO）幼鼠模型中周细胞标志物胶原Ⅰ型蛋白（coll1α1）、血小板源性生长因子β（PDGFRβ）、神经生长因子2（NG2）、平滑肌肌动蛋白（α-SMA）的表达水平的变化，进而探讨周细胞转分化趋势，以及用雷公藤多苷治疗后的干预效果。方法采用UUO模型，将5~6周龄90只雄性幼年SD大鼠，按随机数表法平均分为3组，即假手术组（行手术分离但不结扎左侧输尿管）、模型组（手术结扎左侧输尿管近肾盂段）和雷公藤多苷干预组。分别在术后1、2、3、7、14 d每组各取6只小鼠处死，留取左肾，采用免疫组织化学法检测周细胞标志物coll1α1、PDGFRβ、NG2、α-SMA在肾间质纤维化过程中的表达水平的变化，同时利用Masson染色观测绿染面积（胶原纤维）的大小变化。结果 UUO模型组中coll1α1、PDGFRβ、NG2、α-SMA的表达水平显著高于假手术组（P＜0．01），随着梗阻时间的延长，其表达水平均呈增高的趋势，纤维化程度逐渐加重；UUO模型组中Masson染色蓝染面积随着实验时间的增加而增大；雷公藤多苷干预组各时间点coll1α1、PDGFRβ、NG2、α-SMA的表达水平均低于模型组（P＜0．01），纤维化程度较其减轻，但仍高于假手术组（P＜0．01）。结论肾间质纤维化过程中，周细胞发生了转分化，治疗组雷公藤多苷可能有一定的抑制周细胞转分化作用，从而延缓纤维化的进程。

Objective To determine the peritubular pericyte transdifferentiational tendency of renal interstitial fibrosis and the efficacy of tripterygium wilfordii based on the expressional levels of collagen typeα1 （coll1α1）, platelet-derived growth factor receptor β（PDGFRβ）, neurogenic growth factor 2 （NG2） and α-smooth muscle actin （α-SMA） in young rats with unilateral ureteral obstruction （UUO）. Methods Following establishment of the model of U-UO, ninety SD male mice five weeks of age were assigned to be subject to surgical procedures without ligation of the left urinary duct （sham-operated group, n=30） surgical ligation of the left urinary duct in the vicinity of renal pelvis （UUO group, n=30） and tripterygium wilfordii polyglycoside treatment following ligation of the left urinary duct （treat-ment group, n=30）. Six mice from individual groups were sacrificed at days 1, 2, 3, 7 and 14. This allowed extraction of the left kidney for immunohistochemistry assay of the pericytes markers, including coll1α1, PDGFRβ, NG2 and α-SMA during renal interstitial fibrosis. Meanwhile, the positively stained areas （in green） were measured by Masson staining. Results The expression levels of coll1α1, PDGFRβ, NG2 and α-SMA were increased in group UUO com-pared with sham-operation group （all P〈0.05）. The magnitude of expression progressively increased with the prolonged time course, indicating aggravated fibrosis. In group UUO, the Masson staining-positive area progressively increased with time. The expression of coll1α1, PDGFRβ, NG2 and α-SMA at all time points was substantially lower in the treatment group than in the UUO group （P〈0.01）, but not in control group. Conclusion The peritubular pericytes demonstrate signs of transdifferentiation during the process of renal interstitial fibrosis in mice with UUO. Intervention with tripterygium wilfordii may inhibit the transdifferentiation of pericytes and hinder the progression of renal intersti-tial fibrosis.