Saika Shizuya, Ikeda Kazuo, Yamanaka Osamu, Flanders Kathleen C, Okada Yuka, Miyamoto Takeshi, Kitano Ai, Ooshima Akira, Nakajima Yuji, Ohnishi Yoshitaka, Kao Winston W-Y
Department of Ophthalmology, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-0012, Japan.
Am J Pathol. 2006 Jun;168(6):1848-60. doi: 10.2353/ajpath.2006.050980.
Animal cornea is an avascular transparent tissue that is suitable for research on wound healing-related scarring and neovascularization. Here we show that loss of tumor necrosis factor alpha (TNFalpha) potentiates the undesirable, pathogenic response of wound healing in an alkali-burned cornea in mice. Excessive invasion of macrophages and subsequent formation of a vascularized scar tissue were much more marked in TNFalpha-null knockout (KO) mice than in wild-type mice. Such an unfavorable outcome in KO mice was abolished by Smad7 gene introduction, indicating the involvement of transforming growth factor beta or activin/Smad signaling. Bone marrow transplantation from wild-type mice normalized healing of the KO mice, suggesting the involvement of bone marrow-derived inflammatory cells in this phenomenon. Co-culture experiments showed that loss of TNFalpha in macrophages, but not in fibroblasts, augmented the fibroblast activation as determined by detection of alpha-smooth muscle actin, the hallmark of myofibroblast generation, mRNA expression of collagen Ialpha2 and connective tissue growth factor, and detection of collagen protein. TNFalpha in macrophages may be required to suppress undesirable excessive inflammation and scarring, both of which are promoted by transforming growth factor beta, and for restoration of tissue architecture in a healing alkali-burned cornea in mice.
动物角膜是一种无血管的透明组织，适用于与伤口愈合相关的瘢痕形成和新生血管形成的研究。在此我们表明，肿瘤坏死因子α（TNFα）的缺失增强了小鼠碱烧伤角膜中伤口愈合的不良致病反应。在TNFα基因敲除（KO）小鼠中，巨噬细胞的过度浸润以及随后血管化瘢痕组织的形成比野生型小鼠更为明显。通过导入Smad7基因，KO小鼠中的这种不良结果得以消除，这表明转化生长因子β或激活素/Smad信号通路参与其中。来自野生型小鼠的骨髓移植使KO小鼠的愈合恢复正常，这表明骨髓来源的炎症细胞参与了这一现象。共培养实验表明，巨噬细胞而非成纤维细胞中TNFα的缺失增强了成纤维细胞的活化，这是通过检测α平滑肌肌动蛋白（肌成纤维细胞生成的标志）、Iα2型胶原蛋白和结缔组织生长因子的mRNA表达以及胶原蛋白的检测来确定的。巨噬细胞中的TNFα可能是抑制不良的过度炎症和瘢痕形成所必需的，这两者均由转化生长因子β促进，并且对于小鼠碱烧伤角膜愈合过程中组织结构的恢复也是必需的。
