Yokozeki M, Moriyama K, Shimokawa H, Kuroda T
Department of Maxillo-Facial Orthognathics, Graduate School of Dentistry, Tokyo Medical and Dental University, Japan.
Exp Cell Res. 1997 Mar 15;231(2):328-36. doi: 10.1006/excr.1997.3473.
The effects of transforming growth factor-beta 1 (TGF-beta 1) on normal rat palatal fibroblasts in vitro were investigated in the present study in order to unravel the precise mechanisms by which the phenotypic modulation of fibroblasts occurs during the scar formation process. TGF-beta 1 dramatically changed the morphology of normal palatal fibroblasts from polygonal into an elongated shape, which was very similar to that of fibroblasts derived from experimental immature scar tissue in rat palatal mucosa. This morphological transition was concomitant with an increase in the expression of alpha-smooth muscle (alpha-SM) actin protein, a marker for myofibroblasts, when determined by immunocytochemistry. An immunoblot study also revealed that alpha-SM actin expression in palatal fibroblasts became evident after 24 h of TGF-beta 1 treatment and increased time-dependently up to 72 h. Northern blot analysis showed that TGF-beta 1 stimulated endogenous TGF-beta 1 mRNA expression in palatal fibroblasts within 24 h. Neither epidermal growth factor nor basic fibroblast growth factor had any effect on either alpha-SM actin expression or TGF-beta 1 mRNA expression. Pretreatment of palatal fibroblasts with TGF-beta 1 significantly increased the contractile capacity in a three-dimensional collagen gel culture, even when the culture medium was deprived of TGF-beta 1 for 72 h of the experimental period. Moreover, the contractility of scar fibroblasts, which highly expressed alpha-SM actin protein and TGF-beta 1 mRNA, was significantly lowered by a neutralizing antibody to TGF-beta 1. These data strongly suggest that TGF-beta 1 is a potential inducer of phenotypic expression of myofibroblasts in palatal fibroblasts and that auto-induction of TGF-beta 1 mRNA expression may play an important role in the scar formation process in palatal mucosa.
为了阐明在瘢痕形成过程中，成纤维细胞表型调节的确切机制，本研究探讨了转化生长因子β1（TGF-β1）对正常大鼠腭部成纤维细胞的体外作用。TGF-β1显著改变了正常腭部成纤维细胞的形态，使其从多边形变为细长形，这与大鼠腭黏膜实验性未成熟瘢痕组织来源的成纤维细胞形态非常相似。通过免疫细胞化学检测发现，这种形态转变伴随着肌成纤维细胞标志物α-平滑肌（α-SM）肌动蛋白表达的增加。免疫印迹研究还显示，腭部成纤维细胞在TGF-β1处理24小时后，α-SM肌动蛋白表达开始明显，并随时间依赖性增加，直至72小时。Northern印迹分析表明，TGF-β1在24小时内刺激了腭部成纤维细胞内源性TGF-β1 mRNA的表达。表皮生长因子和碱性成纤维细胞生长因子对α-SM肌动蛋白表达或TGF-β1 mRNA表达均无影响。即使在实验期72小时的培养基中去除TGF-β1，用TGF-β1预处理腭部成纤维细胞也能显著提高三维胶原凝胶培养中的收缩能力。此外，对TGF-β1的中和抗体可显著降低高表达α-SM肌动蛋白和TGF-β1 mRNA的瘢痕成纤维细胞的收缩性。这些数据强烈表明，TGF-β1是腭部成纤维细胞中肌成纤维细胞表型表达的潜在诱导剂，TGF-β1 mRNA表达的自诱导可能在腭黏膜瘢痕形成过程中起重要作用。
