Li D Q, Lee S B, Tseng S C
Ocular Surface and Tear Center Department of Ophthalmology Bascom Palmer Eye Institute USA Florida, Miami, FL 33101, USA.
Curr Eye Res. 1999 Aug;19(2):154-61. doi: 10.1076/ceyr.19.2.154.5321.
We have reported that three patterns of cytokine expression are potentially involved between epithelia and fibroblasts of the human ocular surface. The TGF-beta family is a prototypical fibrogenic cytokine responsible for fibroblast activation in wound healing. We investigated how the TGF-beta family is differentially expressed and regulated in cultured human corneal, limbal and conjunctival fibroblasts.
Human corneal (HCF), limbal (HLF) and conjunctival fibroblast (HJF) were cultured in DMEM-10% FBS until confluence and switched to serum-free DMEM-ITS for 48 h before adding 10 ng/ml of each of eight cytokines for 4 h in three separate experiments. Total RNA was isolated and subjected to Northern hybridization with GAPDH as a control. ELISA was used to determine TGF-beta1 and TGF-beta2 proteins in the media.
All three isoforms of TGF-beta and three types of TGF-betaR were expressed by HCF, HLF and HJF. Expression of TGF-beta1 mRNA was strongest and upregulated by the three TGF-betas in all three types of fibroblast. PDGF-BB and TGF-alpha slightly increased TGF-beta1 mRNA. TGF-betas also upregulated TGF-beta3 mRNA in HJF. TGF-betaRI mRNA was the only receptor upregulated by TGF-betas. TGF-betaRII and TGF-betaRIII mRNA were not regulated by all cytokines tested.
TGF-betas auto-induction is the major mechanism upregulating TGF-beta1 expression. Promotion of TGF-beta3 by the TGF-betas may have a special role in HJF. Differential expression and regulation of TGF-betas and TGF-betaRs suggest that each TGF-beta isoform may have specific functions in different ocular surface fibroblasts. No cytokine tested can downregulate TGF-beta1 and the TGF-betaRs.
我们曾报道，人眼表上皮细胞与成纤维细胞之间可能存在三种细胞因子表达模式。转化生长因子-β（TGF-β）家族是一种典型的促纤维化细胞因子，在伤口愈合过程中负责激活成纤维细胞。我们研究了TGF-β家族在培养的人角膜、角膜缘和结膜成纤维细胞中是如何差异表达和调控的。
将人角膜成纤维细胞（HCF）、角膜缘成纤维细胞（HLF）和结膜成纤维细胞（HJF）在含10%胎牛血清的DMEM中培养至汇合，然后换成无血清的DMEM-ITS培养48小时，之后在三个独立实验中分别加入10 ng/ml的八种细胞因子中的每一种，作用4小时。提取总RNA，以甘油醛-3-磷酸脱氢酶（GAPDH）作为对照进行Northern杂交。采用酶联免疫吸附测定法（ELISA）测定培养基中TGF-β1和TGF-β2蛋白的含量。
HCF、HLF和HJF均表达TGF-β的三种同工型以及三种类型的TGF-β受体。在所有三种类型的成纤维细胞中，TGF-β1 mRNA的表达最强，且受到三种TGF-β的上调。血小板源性生长因子-BB（PDGF-BB）和TGF-α略微增加TGF-β1 mRNA的表达。TGF-β也上调HJF中TGF-β3 mRNA的表达。TGF-βRI mRNA是唯一受TGF-β上调的受体。TGF-βRII和TGF-βRIII mRNA不受所测试的所有细胞因子的调控。
TGF-β的自身诱导是上调TGF-β1表达的主要机制。TGF-β对TGF-β3的促进作用可能在HJF中具有特殊作用。TGF-β及其受体的差异表达和调控表明，每种TGF-β同工型可能在不同的眼表成纤维细胞中具有特定功能。所测试的细胞因子均不能下调TGF-β1和TGF-β受体。
