Department of Dermatology and Venereology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany.
Eur J Cell Biol. 2022 Sep-Nov;101(4):151276. doi: 10.1016/j.ejcb.2022.151276. Epub 2022 Sep 23.
Early lethality of mice with complete deletion of the matrix metalloproteinase MMP14 emphasized the proteases' pleiotropic functions. MMP14 deletion in adult dermal fibroblasts (MMP14) caused collagen type I accumulation and upregulation of MMP3 expression. To identify the compensatory role of MMP3, mice were generated with MMP3 deletion in addition to MMP14 loss in fibroblasts. These double deficient mice displayed a fibrotic phenotype in skin and tendons as detected in MMP14 mice, but no additional obvious defects were detected. However, challenging the mice with full thickness excision wounds resulted in delayed closure of early wounds in the double deficient mice compared to wildtype and MMP14 single knockout controls. Over time wounds closed and epidermal integrity was restored. Interestingly, on day seven, post-wounding myofibroblast density was lower in the wounds of all knockout than in controls, they were higher on day 14. The delayed resolution of myofibroblasts from the granulation tissue is paralleled by reduced apoptosis of these cells, although proliferation of myofibroblasts is induced in the double deficient mice. Further analysis showed comparable TGFβ1 and TGFβR1 expression among all genotypes. In addition, in vitro, fibroblasts lacking MMP3 and MMP14 retained their ability to differentiate into myofibroblasts in response to TGFβ1 treatment and mechanical stress. However, in vivo, p-Smad2 was reduced in myofibroblasts at day 5 post-wounding, in double, but most significant in single knockout, indicating their involvement in TGFβ1 activation. Thus, although MMP3 does not compensate for the lack of fibroblast-MMP14 in tissue homeostasis, simultaneous deletion of both proteases in fibroblasts delays wound closure during skin repair. Notably, single and double deficiency of these proteases modulates myofibroblast formation and resolution in wounds.
基质金属蛋白酶 MMP14 完全缺失的小鼠早期致死性强调了蛋白酶的多功能性。成年真皮成纤维细胞中 MMP14 的缺失导致 I 型胶原积累和 MMP3 表达上调。为了确定 MMP3 的代偿作用，在成纤维细胞中除 MMP14 缺失外，还生成了 MMP3 缺失的小鼠。这些双缺失小鼠在皮肤和肌腱中表现出与 MMP14 小鼠相同的纤维化表型，但未检测到其他明显缺陷。然而，用全厚度切除伤口对这些小鼠进行挑战，导致双缺失小鼠早期伤口的闭合比野生型和 MMP14 单敲除对照更慢。随着时间的推移，伤口闭合，表皮完整性得到恢复。有趣的是，在创伤后第 7 天，所有敲除小鼠的伤口中肌成纤维细胞的密度低于对照组，而在第 14 天则更高。肉芽组织中肌成纤维细胞的延迟消退与这些细胞凋亡减少相平行，尽管双缺失小鼠中肌成纤维细胞的增殖被诱导。进一步分析表明，所有基因型之间 TGFβ1 和 TGFβR1 的表达相当。此外，在体外，缺乏 MMP3 和 MMP14 的成纤维细胞保留了在 TGFβ1 处理和机械应激下分化为肌成纤维细胞的能力。然而，在体内，在创伤后第 5 天，双敲除但最显著的是单敲除小鼠的肌成纤维细胞中 p-Smad2 减少，表明它们参与了 TGFβ1 的激活。因此，尽管 MMP3 不能补偿组织稳态中成纤维细胞 MMP14 的缺乏，但成纤维细胞中两种蛋白酶的同时缺失会延迟皮肤修复过程中的伤口闭合。值得注意的是，这些蛋白酶的单敲除和双敲除会调节伤口中肌成纤维细胞的形成和消退。
