Akt-Smad信号轴在压力治疗增生性瘢痕中的作用机制

Scarring is a natural repair response to cutaneous injury. Abnormal scar growth will result in the pathological scar that is limited to injury scope called hypertrophic scar in clinic. So far, no treatment can heal them completely. However, pressure is a kind of effective treatment which has been widely accepted by most patients and doctors in clinic that curative effect was approved extensively. But the mechanism related to pressure treatment has not been studyed thoroughly. Signal pathways play key roles in all kinds of cells' changes. Thus, we intend to study the molecular mechanism in pressure treatment and lay the foundation for molecular target therapy. Based on the above destination, we search for document literatures largely and discover that Smad and Akt signal pathway might both play important roles in the pressure treatment in hypertrophic scar. Smad signal pathway, an important intermediary molecule in TGF-β superfamily signal transduction, participates in most biological behaviors of hypertrophic scar. It's supposed to be the most important signal pathway in the progress of hypertrophic scar formation. Acording to our previous studies, hypertrophic scar can be effectively restrained by interfering with Smad signal pathway. In addition, Akt signal pathway is the main pressure sensitivity signal pathway of fibroblast, which can promote the process of tissue fibrosis. There may be some connection betwwen Akt and Smad signal pathways in the course of hyprotrophic scarring. So the Akt-Smad signal axis concept is proposed for the first time in our project, which is supposed to be the the main mechanism in pressure thearpy for hapertrophic scar. Firstly, we will study the main proteins' expression of Akt and Smad signal pathway in fibroblast of hypertrophic scar under different pressure to discuss whether there is possible relationship between Akt and Smad signal pathway. Secondly, to investigate whether Smad signal can be influenced by controlling the Akt signal activity or not. So we can ascertain wherher Ask-Smad Signal axis exists or not. Finally, varying pressure applied to hypertrophic scar in the animal experiments by controlling the Akt signal to observe the main proteins' change of TGF-β1/Smad signal pathway, and then to discuss the influences of Ask-Smad signal asis in the hypertrophic scar fibroblast growth, transformation and extracellular matrix deposition. If we can prove the exist of Ask-Smad signal axis, a new theory for pressure treatment in hypertrophic scar could be provided.

压力作为增生性瘢痕的有效治疗手段，临床上已被广泛认可。Smad信号参与了增生性瘢痕的许多生物学行为，被认为是增生性瘢痕形成的最重要信号通路。我们的前期研究表明，干扰Smad信号通路可以有效抑制瘢痕增生。Akt信号通路是成纤维细胞主要的压力敏感性信号通路，能促进组织纤维化的进程。本项目首次提出了Akt-Smad信号轴概念，假设其为压力治疗增生瘢痕的主要作用机制。首先研究压力下增生性瘢痕成纤维细胞Akt信号和Smad信号的变化；然后观察Akt信号抑制与否对Smad信号通路各环节的影响，由此判断Akt-Smad信号轴是否存在。最后，动物体内试验将不同模式的压力作用于增生性瘢痕，通过调控Akt信号，观察TGF-β1/Smad信号通路的变化，进而探究对增生性瘢痕成纤维细胞的生长、转分化以及细胞外基质沉积的影响，为压力治疗增生性瘢痕提供理论依据。

作为创面愈合的异常结局，增生性瘢痕是皮肤损伤后成纤维细胞异常增殖、胶原蛋白、纤连蛋白、氨基多聚糖等细胞外基质的过度沉积而形成的皮肤异常凸起。由于其发病机制的多样性、复杂性和不确定性，针对增生性瘢痕的治疗仍是临床上颇为棘手的难题。压力治疗是一种防治增生性瘢痕的非损伤性的物理治疗方法，研究表明，压力可降低真皮胶原沉积、促进胶原分解，使螺旋状紊乱的胶原束转变为平行排列，从而使瘢痕组织更接近正常皮肤。目前，压力治疗因其确切的临床疗效已成为增生性瘢痕防治的首选方案。然而，压力作用于增生性瘢痕的疗效都是基于临床观察和经验，由于缺少合适的体外研究方法和动物模型，压力治疗的确切作用机制至今尚不清晰。有学者认为压力通过减少增生性瘢痕中局部毛细血管的血流量，使瘢痕局部处于缺氧状态，抑制真皮成纤维细胞活性，使其增殖、分化及合成细胞外基质的能力降低，从而达到抑制瘢痕增生的效果。然而，研究者们对于压力 — 这一机械性的外力如何转变为人体内分子生物学信息、改变成纤维细胞生物学行为的机制知之甚少。.本课题利用Flexercell® （FX-4000C™）体外压力培养装置模拟压力作用于真皮成纤维细胞的体内环境，通过人类全基因组表达谱芯片对压力作用前后的差异表达基因进行初步筛选，通过生物信息学分析进一步筛选出压力作用的靶基因(mTOR及PGE2)和潜在的信号通路(压力/mTOR通路，PGE2/EP2/Smad通路)，通过正反验证压力是通过同时抑制mTOR通路中I型及II型受体，继而抑制mTOR及其下游信号通路来抑制瘢痕增生；压力也可通过抑制PEG2的表达来抑制瘢痕增生。同时建立压力治疗增生性瘢痕的动物模型，进一步验证体外实验结果中的关键靶基因及信号通路，阐述机械压力对细胞重建机制及细胞内生物信息传递的调控，为利用压力治疗增生性瘢痕提供可靠的基础理论依据，使压力治疗在临床上的应用更加科学、规范。