Kondo Shuji, Kagami Shoji, Urushihara Maki, Kitamura Akiko, Shimizu Maki, Strutz Frank, Müller Gerhard A, Kuroda Yasuhiro
Department of Pediatrics, School of Medicine, University of Tokushima, Kuramoto-cho-3-chome, Tokushima 770-8503, Japan.
Biochim Biophys Acta. 2004 Aug 23;1693(2):91-100. doi: 10.1016/j.bbamcr.2004.05.005.
Renal tubulointerstitial fibrosis is the common final pathway leading to end-stage renal failure. Tubulointerstitial fibrosis is characterized by fibroblast proliferation and excessive matrix accumulation. Transforming growth factor-beta1 (TGF-beta1) has been implicated in the development of renal fibrosis accompanied by alpha-smooth muscle actin (alpha-SMA) expression in renal fibroblasts. To investigate the molecular and cellular mechanisms involved in tubulointerstitial fibrosis, we examined the effect of TGF-beta1 on collagen type I (collagen) gel contraction, an in vitro model of scar collagen remodeling. TGF-beta1 enhanced collagen gel contraction by human renal fibroblasts in a dose- and time-dependent manner. Function-blocking anti-alpha1 or anti-alpha2 integrin subunit antibodies significantly suppressed TGF-beta1-stimulated collagen gel contraction. Scanning electron microscopy showed that TGF-beta1 enhanced the formation of the collagen fibrils by cell attachment to collagen via alpha1beta1 and alpha2beta1 integrins. Flow cytometry and cell adhesion analyses revealed that the stimulation of renal fibroblasts with TGF-beta1 enhanced cell adhesion to collagen via the increased expression of alpha1 and alpha2 integrin subunits within collagen gels. Fibroblast migration to collagen was not up-regulated by TGF-beta1. Furthermore, TGF-beta1 increased the expression of a putative contractile protein, alpha-SMA, by human renal fibroblasts in collagen gels. These results suggest that TGF-beta1 stimulates fibroblast-collagen matrix remodeling by increasing both integrin-mediated cell attachment to collagen and alpha-SMA expression, thereby contributing to pathological tubulointerstitial collagen matrix reorganization in renal fibrosis.
肾小管间质纤维化是导致终末期肾衰竭的常见最终途径。肾小管间质纤维化的特征是成纤维细胞增殖和细胞外基质过度积聚。转化生长因子-β1（TGF-β1）与肾纤维化的发生有关，伴有肾成纤维细胞中α-平滑肌肌动蛋白（α-SMA）的表达。为了研究参与肾小管间质纤维化的分子和细胞机制，我们检测了TGF-β1对I型胶原（胶原蛋白）凝胶收缩的影响，这是一种瘢痕胶原重塑的体外模型。TGF-β1以剂量和时间依赖性方式增强人肾成纤维细胞的胶原凝胶收缩。功能阻断性抗α1或抗α2整合素亚基抗体显著抑制TGF-β1刺激的胶原凝胶收缩。扫描电子显微镜显示，TGF-β1通过细胞经由α1β1和α2β1整合素附着于胶原而增强胶原纤维的形成。流式细胞术和细胞黏附分析显示，用TGF-β1刺激肾成纤维细胞可通过胶原凝胶内α1和α2整合素亚基表达的增加来增强细胞对胶原的黏附。TGF-β1并未上调成纤维细胞向胶原的迁移。此外，TGF-β1增加了人肾成纤维细胞在胶原凝胶中一种假定的收缩蛋白α-SMA的表达。这些结果表明，TGF-β1通过增加整合素介导的细胞与胶原的黏附以及α-SMA的表达来刺激成纤维细胞-胶原基质重塑，从而促进肾纤维化中病理性肾小管间质胶原基质的重组。
