血管紧张素转换酶对皮肤瘢痕形成的调控作用和机制研究

Wound scarring is always a major focus in the field of plastic surgery due to its difficulty in clinical treatment. However, the molecular mechanism of scar formation is not well understood. In recent years, it has been recoganized that the local renin-angiotensin system (RAS) participates in the fibrosis of multiple ograns via promoting cellular proliferation and synthesis of extracellular matrix. However, these studies of RAS in scar only focused on the effects of angiotensin II (Ang II); the functional diversity of angiotensin converting enzyme (ACE) has not been recognized. Recently, we unveiled that ACE plays various roles in the immune system, and multiple physiologic functions are regulated by ACE through a variety of bioactive peptides; we also verified that ACE is involved in scar formation in our preliminary experiments. Based on these facts, we propose here to investigate how ACE and the bioactive peptides regulated by ACE (Ang II、SP、AcSDKP and Ang 1-7) are invovled in wound healing and scar formation. In our study, cells and mice expressing no ACE (ACE knockout), normal ACE (wild type) and excessive ACE (transgene) will be used to investigate the impacts of ACE on scar formation in vitro and in vivo. Furthermore, we will evaluate the distictive roles of ACE expressed by skin tissue and inflammatory cells by means of bone marrow transplantation. Finally, the bioactive peptides and the downstreem molecue pathways will be dissected and studied. The completion of this proposal will not only extend our knownledge and understanding about wound healing and scar formation, but ultimately, may provide new targets for the treatment of scar by aiming at ACE, peptides and their intracellular pathways as well.

瘢痕研究一直是整形外科界的焦点之一，但其形成机制尚不明确。近年发现局部肾素-血管紧张素系统（RAS）可通过促细胞增殖和细胞外基质合成参与多种器官纤维化，但目前RAS与瘢痕相关性的研究仅局限于血管紧张素II（Ang II）的效应，对血管紧张素转换酶（ACE）功能多样性的认识尤其不足。我们前期发现ACE在免疫系统中具有广泛作用，并通过多种活性肽调控多种生理功能；预实验证实了ACE参与瘢痕形成。据此，本项目研究ACE及其调控的纤维化相关活性肽（Ang II、P物质、AcSDKP、Ang 1-7）在瘢痕形成中的作用，揭示其调控模式和机制。本研究采用ACE无表达（基因敲除）、正常、过表达（转基因）的细胞系和鼠系进行体内体外分析，论证其调控作用；辨别皮肤和炎症细胞ACE功能的独特性；并证明参与的活性肽及其下游分子通路。该研究将拓展对瘢痕形成机制的认识，有利于提出以ACE及其通路为靶点的瘢痕治疗新方案。

瘢痕研究一直是整形外科界的焦点之一，但其形成机制尚不明确。近年发现局部肾素-血管紧张素系统（RAS）可通过促细胞增殖和细胞外基质合成参与多种器官纤维化，但目前RAS与瘢痕相关性的研究仅局限于血管紧张素II（Ang II）的效应，对血管紧张素转换酶（ACE）功能多样性的认识尤其不足。我们前期发现ACE在免疫系统中具有广泛作用，并通过多种活性肽调控多种生理功能；预实验证实了ACE参与瘢痕形成。据此，我们系统性地开展了对ACE在瘢痕形成中的作用的研究，揭示其调控模式和机制。首先，我们在体系外小鼠细胞中利用细胞共培养不同浓度的ACEI或者野生型小鼠成纤维细胞和ACE无表达（基因敲除）小鼠成纤维细胞分别培养比较的方法，研究细胞的增值及胶原表达情况。研究证实ACE 对瘢痕形成具有调控作用，减少ACE的表达有助于降低成纤维细胞的增生及胶原的沉积情况。其次，我们分别在大鼠和小鼠体内开展了进一步研究，探究ACE对于瘢痕的调控作用是否在体内同样适用。我们的研究显示不论是在大鼠还是小鼠体内，ACE都具有类似体外实验的作用。在伤口愈合过程中，减少ACE的表达有助于调控成纤维细胞的增生及分布，改善胶原沉积，从而减小瘢痕。然后，我们研究还发现，在瘢痕愈合过程中ACE可来源于骨髓和皮肤组织，任意来源的减少都有助于改善瘢痕。进一步分析显示，骨髓和皮肤ACE通过影响炎症细胞和生长因子，调节TGF-β1/Smad和TGF-β1/TAK1这两条通路来影响皮肤瘢痕形成。该研究将拓展了瘢痕形成机制的认识，有利于提出以ACE及其通路为靶点的瘢痕治疗新方案。