SHIP1/PI3K/AKT通路在创面局部低表达miR-155拮抗增生性瘢痕形成中的作用及机制研究

Hypertrophic scar is difficult to treat in clinic. Literature and clinical trials confirmed that inhibition of wound inflammation could improve wound appearance. Our study shows that low expression of miR-155 at local wound can decrease inflammatory reaction and inhibit the hypertrophic scar formation, but the specific regulatory mechanism is not clear. SH2 structure containing inositol phosphatase 1 (SHIP1) can negative regulation of the PI3K/AKT pathway and play an important role in the proliferation, differentiation and migration of inflammatory cells in the wound. It was reported that SHIP1 mRNA is one of the important targets of miR-155. Accordingly, inhibition the expression of miR-155 can enhance SHIP1 activity, and inhibit the activation of PI3K/AKT pathway, attenuate the inflammatory response, inhibit the hypertrophic scar formation. This study intends to use the full thickness skin defect model confirmed the low expression of miR-155 antagonistic hyperplasia scar function; detect the expression of SHIP1 and PI3K/Akt pathway downstream molecular to confirm the modulation effect of miR-155; and the use of pathway inhibitors/siRNA anti-fibrosis verification on cells and animals. This study will elucidate the anti-fibrosis mechanism of miR-155 scar, and lay the foundation for the prevention and treatment of hypertrophic scar.

增生性瘢痕是临床治疗的难点。文献报道及临床试验证实抑制创面局部炎症反应能改善创面外观，且疗效显著。课题组前期研究证实，创面局部低表达miR-155通过降低炎症反应而拮抗疤痕形成，但其具体调控机制尚不清楚。含SH2结构的肌醇磷酸酶1（SHIP1）通过负性调控PI3K/AKT通路，在创面炎性细胞增殖、迁移及分化中发挥重要调控作用。文献报道SHIP1是miR-155的重要作用靶点之一。据此提出，低表达miR-155可以通过增强SHIP1活性抑制PI3K/AKT通路活化，减弱炎症反应，进而抑制增生性瘢痕形成。本研究拟采用全层皮肤缺损模型证实低表达miR-155拮抗增生性瘢痕的功能；对SHIP1及PI3K/AKT通路关键分子检测，探讨miR-155对其调节作用；并利用通路抑制剂/siRNA对细胞及动物模型进行抗纤维化验证。该研究将阐明miR-155抗瘢痕纤维化机制，为增生性瘢痕的预防及治疗奠定基础。

各种急慢性创面所致增生性瘢痕有较高发生率，是临床治疗的难点。文献报道及临床试验证实抑制创面局部炎症反应可减轻增生性疤痕形成，且对创面愈合速度无明显影响。众多研究证实巨噬细胞过度炎性因子分泌从而刺激成纤维细胞增殖及胶原分泌在增生性疤痕形成中起重要作用。miRNAs通过调节基因表达而在众多病理及生理过程中发挥重要调控作用，miR-155在巨噬细胞炎性因子分泌及纤维化疾病中起重要作用，但其在增生性疤痕形成中的作用尚未探究。本研究首次在动物模型上证实创面局部低表达miR-155可通过降低局部炎症反应而拮抗增生性疤痕形成，同时对创面愈合速度无明显影响。体外研究证实，低表达miR-155可明显抑制巨噬细胞炎性因子分泌水平，而低表达miR-155对成纤维细胞增殖及胶原分泌物明显影响。进一步机制探索发现低表达miR-155通过上调靶点SHIP1的表达而抑制PI3K/Akt通路活性，从而抑制巨噬细胞的炎性因子分泌功能。通过巨噬细胞与成纤维细胞共培养模型发现，巨噬细胞共培养可刺激成纤维细胞增殖及胶原分泌，而巨噬细胞低表达miR-155可通过抑制PI3K/Akt通路拮抗其对成纤维细胞增殖的刺激作用。通过本研究我们发现低表达miR-155通过SHIP1靶点抑制巨噬细胞PI3K/Akt通路活性，进而减少其炎性因子分泌，从而减轻对成纤维细胞的增殖及胶原分泌的刺激作用，减轻创面愈合后增生性疤痕形成。本研究进一步探索了增生性疤痕形成原因、明确了miR155抗瘢痕纤维化作用并对其机制进行了明确，为增生性瘢痕的预防及应用miR-155治疗奠定了基础。