Ricardo S D, Ding G, Eufemio M, Diamond J R
Department of Medicine, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, Hershey 17033, USA.
Am J Physiol. 1997 Jun;272(6 Pt 2):F789-98. doi: 10.1152/ajprenal.1997.272.6.F789.
We assessed whether levels of renal reactive oxygen species (ROS) and antioxidant enzymes are perturbed in rats following unilateral ureteral obstruction (UUO). The mechanism of catalase perturbation was investigated using proximal tubule suspensions following stimulation with transforming growth factor (TGF)-beta and interleukin (IL)-1 and in a proximal tubular cell line (OKC) subjected to cyclic mechanical stretch, which mimics the early hydrodynamic derangement after UUO. Levels of catalase and copperzinc superoxide dismutase (Cu,Zn-SOD) mRNA from 96-h UUO rats showed a 5.5-fold (P < 0.001) and 5.0-fold (P < 0.001) decrease, respectively, compared with the contralateral unobstructed kidney (CUK). Levels of superoxide anion and hydrogen peroxide showed a significant 1.8-fold (P < 0.0001) and 14.0-fold (P < 0.0001) increase, respectively, in 96-h UUO kidney slice cultures. In situ hybridization and immunohistochemistry showed Cu,Zn-SOD and catalase mRNA and protein transcription expressed in proximal tubules of UUO and CUK specimens. Catalase mRNA levels were markedly downregulated following a 1-h exposure of isolated proximal tubules to TGF-beta (0.1-10 ng) and IL-1 (1-5 ng), in comparison to control proximal tubular suspensions. OKC subjected to cyclic mechanical stretch for 1-24 h had marked decrements in catalase mRNA levels, compared with unstretched cells at the same time point. These results indicate that a primary downregulation of proximal tubular Cu,Zn-SOD and catalase expression develops in the proximal tubules of UUO with consequent increments in cortical oxidant levels. These findings suggest that either an early mechanical disturbance produced by UUO or local tubular generation of cytokines can reduce tubular catalase expression. The downregulation of catalase mRNA expression, together with increased oxidant stress in the rat renal cortex post-UUO, may amplify the proinflammatory state of experimental hydronephrosis culminating in tubulointerstitial injury and fibrosis.
我们评估了单侧输尿管梗阻（UUO）后大鼠肾脏活性氧（ROS）水平和抗氧化酶是否受到干扰。使用转化生长因子（TGF）-β和白细胞介素（IL）-1刺激后的近端肾小管悬浮液，以及在经历周期性机械拉伸的近端肾小管细胞系（OKC）中研究过氧化氢酶干扰的机制，该拉伸模拟了UUO后早期的流体动力学紊乱。与对侧未梗阻肾脏（CUK）相比，96小时UUO大鼠的过氧化氢酶和铜锌超氧化物歧化酶（Cu,Zn-SOD）mRNA水平分别下降了5.5倍（P < 0.001）和5.0倍（P < 0.001）。在96小时UUO肾脏切片培养物中，超氧阴离子和过氧化氢水平分别显著增加了1.8倍（P < 0.0001）和14.0倍（P < 0.0001）。原位杂交和免疫组织化学显示，Cu,Zn-SOD和过氧化氢酶mRNA及蛋白转录在UUO和CUK标本的近端小管中表达。与对照近端肾小管悬浮液相比，分离的近端小管暴露于TGF-β（0.1 - 10 ng）和IL-1（1 - 5 ng）1小时后，过氧化氢酶mRNA水平明显下调。与同一时间点未拉伸的细胞相比，经历1 - 24小时周期性机械拉伸的OKC过氧化氢酶mRNA水平显著下降。这些结果表明，在UUO的近端小管中，近端小管Cu,Zn-SOD和过氧化氢酶表达发生原发性下调，从而导致皮质氧化剂水平升高。这些发现表明，UUO产生的早期机械干扰或局部肾小管细胞因子的产生均可降低肾小管过氧化氢酶表达。过氧化氢酶mRNA表达的下调，以及UUO后大鼠肾皮质氧化应激增加，可能会放大实验性肾积水的促炎状态，最终导致肾小管间质损伤和纤维化。
