Pediatric Urology, Univ. of Florida, Gainesville, FL 32610.
Am J Physiol Renal Physiol. 2013 Oct 1;305(7):F1014-21. doi: 10.1152/ajprenal.00620.2012. Epub 2013 Jul 31.
IL-18 is an important mediator of obstruction-induced renal fibrosis and renal tubular epithelial cell (TEC) injury. IL-18's proinflammatory properties have been attributed, in part, to NF-κB activation and the stimulation of cytokine gene expression; however, STAT3 has increasingly been shown to mediate renal fibrotic injury. We therefore hypothesized that IL-18 mediates profibrotic TEC injury via STAT3 activation. Male C57BL6 wild-type mice and transgenic mice for human IL-18-binding protein were subjected to unilateral ureteral obstruction or sham operation. The kidneys were harvested 1 or 2 wk afterward and analyzed for active STAT3 (p-STAT3) expression (Western blotting, immunohistochemistry) and suppressor of cytokine signaling 3 (SOCS3) expression. In a separate arm, renal tubular cells (HK-2) were directly stimulated with IL-18 for 2 days with or without the STAT3 inhibitor S3I-201 (50 μM). Cell lysates were then analyzed for p-STAT3 and SOCS3 expression, profibrotic cellular changes (collagen and α-SMA expression), and tubular cell apoptosis. p-STAT3 and SOCS3 expression increased significantly in response to obstruction; however, a significant reduction in p-STAT3 and SOCS3 expression occurred following 1 wk, but not 2 wk, of obstruction in the presence of IL-18 neutralization. In vitro results similarly demonstrate increased p-STAT3, SOCS3, α-SMA, and collagen III expression, and increased collagen production and TEC apoptosis in response to IL-18 stimulation, but the response was significantly diminished in the presence of STAT3 inhibition. These results demonstrate that IL-18-induces profibrotic cellular changes and collagen production in TECs via STAT3 activation.
白细胞介素 18（IL-18）是一种重要的中介介质，可诱导梗阻性肾纤维化和肾小管上皮细胞（TEC）损伤。IL-18 的促炎特性部分归因于 NF-κB 的激活和细胞因子基因表达的刺激；然而，STAT3 越来越多地被证明介导了肾纤维化损伤。因此，我们假设 IL-18 通过 STAT3 激活介导促纤维化的 TEC 损伤。雄性 C57BL6 野生型小鼠和人白细胞介素 18 结合蛋白转基因小鼠接受单侧输尿管梗阻或假手术。2 周后收获肾脏，并分析活性 STAT3（p-STAT3）表达（Western blot、免疫组化）和细胞因子信号转导抑制物 3（SOCS3）表达。在另一个分支中，将肾小管细胞（HK-2）直接用 IL-18 刺激 2 天，同时使用或不使用 STAT3 抑制剂 S3I-201（50μM）。然后分析细胞裂解物中的 p-STAT3 和 SOCS3 表达、促纤维化的细胞变化（胶原和α-SMA 表达）以及肾小管细胞凋亡。p-STAT3 和 SOCS3 的表达在梗阻后显著增加；然而，在 IL-18 中和后 1 周而不是 2 周，p-STAT3 和 SOCS3 的表达显著降低。体外结果同样表明，在 IL-18 刺激下，p-STAT3、SOCS3、α-SMA 和胶原 III 的表达增加，胶原蛋白产生和 TEC 凋亡增加，但在 STAT3 抑制存在时，反应明显减弱。这些结果表明，IL-18 通过 STAT3 激活诱导 TEC 中的促纤维化细胞变化和胶原产生。
