Chen Wei, Fu Xiaobing, Ge Shili, Sun Tongzhu, Zhou Gang, Jiang Duyin, Sheng Zhiyong
Wound Healing and Cell Biology Laboratory, Burns Institute, 304th Hospital, Trauma Center of Postgraduate Medical College, Academy of Military Medicine Sciences, Beijing, People's Republic of China.
Wound Repair Regen. 2005 Jan-Feb;13(1):68-75. doi: 10.1111/j.1067-1927.2005.130109.x.
Fetal cutaneous wounds that occur in early gestation heal without scar formation. Although much work has been done to characterize the role of transforming growth factor-beta (TGF-beta) isoforms and their receptors in the wound healing process, their roles in scarless wound repair observed in early gestation and their functions in human fetal skin development, and structural and functional maintenance are still not well understood. In this study, we explore the expression and distribution characteristics of three TGF-beta isoforms and their receptors, TGF-betaRI (TBRI) and TGF-betaRII (TBRII), in fetal and postnatal skins to understand the relevance of these five proteins to skin development and elucidate the mechanism(s) underlying the phenotypic transition from scarless to scar-forming healing observed during fetal gestation. Fetal skin biopsies of human embryo were obtained from spontaneous abortions at different gestational ages from 13 to 32 weeks and postnatal skin specimens were collected from patients undergoing plastic surgery. Gene expression and positive immunohistochemical signals of TGF-beta(1), TGF-beta(2), TGF-beta(3), TBRI, and TBRII could all be detected in fetal and postnatal skins. In early gestation, gene expression of TGF-beta(1), TBRI, and TBRII was weaker and protein contents were less compared with postnatal skins (p < 0.05). In contrast, more TGF-beta(2) mRNA transcript was found in early gestation than in late gestation and in postnatal skins, whereas protein content of this growth factor increased during gestation. Lastly, mRNA transcript and protein contents of TGF-beta(3) were apparently higher in early gestation compared to postnatal skin (p < 0.05). In postnatal skin, granules containing the three TGF-beta isoforms were mainly distributed in the cytoplasm and extracellular matrix of epidermal cells, interfollicular keratinocytes, and some fibroblasts. TBRI and TBRII were chiefly located in the cellular membrane of epidermal keratinocytes and some fibroblasts. The endogenous three TGF-beta isoforms and their receptors may be involved in the development of embryonic skin and in the maintenance of cutaneous structure and function, and also in postnatal wound healing. The differential levels of TGF-beta isoforms may provide either a predominantly antiscarring or profibrotic signal upon wounding depending on the gestational period. Lower expression of their receptors in early gestational skins may be a reason for the reduced ability to perceive ligands, ultimately leading to scar-free healing.
发生在妊娠早期的胎儿皮肤伤口愈合后不会形成瘢痕。尽管已经开展了大量工作来描述转化生长因子-β(TGF-β)亚型及其受体在伤口愈合过程中的作用,但它们在妊娠早期观察到的无瘢痕伤口修复中的作用以及在人类胎儿皮肤发育、结构和功能维持中的功能仍未完全清楚。在本研究中,我们探究了三种TGF-β亚型及其受体TGF-βRI(TBRI)和TGF-βRII(TBRII)在胎儿和出生后皮肤中的表达及分布特征,以了解这五种蛋白与皮肤发育的相关性,并阐明在胎儿期观察到的从无瘢痕愈合到瘢痕形成愈合的表型转变的潜在机制。从孕13至32周不同孕周自然流产的人类胚胎获取胎儿皮肤活检样本,并从接受整形手术的患者收集出生后皮肤标本。TGF-β(1)、TGF-β(2)、TGF-β(3)、TBRI和TBRII的基因表达及阳性免疫组化信号在胎儿和出生后皮肤中均能检测到。在妊娠早期,与出生后皮肤相比,TGF-β(1)、TBRI和TBRII的基因表达较弱,蛋白含量较少(p < 0.05)。相反,在妊娠早期发现的TGF-β(2) mRNA转录本比妊娠晚期和出生后皮肤中的更多,而这种生长因子的蛋白含量在妊娠期间增加。最后,与出生后皮肤相比,妊娠早期TGF-β(3)的mRNA转录本和蛋白含量明显更高(p < 0.05)。在出生后皮肤中,含有三种TGF-β亚型的颗粒主要分布在表皮细胞、毛囊间角质形成细胞和一些成纤维细胞的细胞质和细胞外基质中。TBRI和TBRII主要位于表皮角质形成细胞和一些成纤维细胞的细胞膜上。内源性三种TGF-β亚型及其受体可能参与胚胎皮肤的发育以及皮肤结构和功能的维持,也参与出生后伤口愈合。TGF-β亚型的不同水平可能根据妊娠期在受伤时提供主要的抗瘢痕或促纤维化信号。它们的受体在妊娠早期皮肤中的较低表达可能是感知配体能力降低的一个原因,最终导致无瘢痕愈合。