β2肾上腺素受体通过TGF-β1/Smad3信号通路调控创面愈合中纤维增生的作用

目的：探讨β2肾上腺素受体（ADRB2）在创面愈合过程中对纤维增生的调控机制。方法：小鼠背部皮肤注射非特异性敲减ADRB2基因的腺相关病毒（AAV-ADRB2组）和对照病毒（AAV-NC组）21天后，在背部建立全层皮肤缺损创面愈合模型。记录术后1、3、5、7天创面愈合率；采用H-E染色、Masson染色和免疫组化观察创面组织结构、纤维化程度及α-SMA表达；定量PCR检测ADRB2、基质金属蛋白酶（MMP）mRNA水平；western blot检测COL1a1、COL3a1、TGF-β1、Smad3蛋白表达水平。结果：术后第5、7天，AAV-ADRB2组创面愈合率显著下降（P<0.05），伴随表皮增厚、炎症增多、纤维细胞减少、胶原沉积降低；α-SMA水平显著下降（P<0.05）；I型/III型胶原比例减少（P<0.05）；ADRB2 mRNA水平显著降低（P<0.01），MMP-1和MMP-8 mRNA水平升高（P<0.01）；TGF-β1/Smad3蛋白水平显著下降（P<0.05）。结论：ADRB2敲减通过抑制TGF-β1/Smad3信号通路，减少创面纤维化反应和结缔组织含量，提高MMP mRNA水平，降低I型/III型胶原比例。

The role of β2 adrenergic receptor in fibrogenesis during wound healing via TGF-β1/Smad3 signaling pathway

Objective: To investigate the underlying mechanism of β2 adrenergic receptor (ADRB2) in fibrogenesis during wound healing. Methods: 21 days after one-off subcutaneous injection of adenovirus-associated viruses (AAV) to non-specifically knock down ADRB2 gene (AAV-ADRB2 group) and the corresponding control virus (AAV-NC group) into the dorsal skin of mice, a full-thickness skin defected wound healing murine model was established. Wound healing rates were recorded at the 1st, 3rd, 5th, and 7th after operation. Histological examinations by H-E, Masson staining, and immunohistochemistry were conducted to observe wounded skin tissue structure, fibrosis, and α-SMA protein expression; quantitative PCR was employed to analyze ADRB2 and matrix metalloproteinase (MMP) mRNA levels; western blotting was utilized to assess the protein expression levels of COL1a1, COL3a1, TGF-β1, and Smad3. Results: On postoperative day 5 and 7, the wound healing rate of the AAV-ADRB2 group significantly decreased (P< 0.05), accompanied by a series pathological changes, including thickened epidermis, exaggerated inflammation, reduced fibroblast count, and inhibited collagen deposition; the α-SMA expression showed a significant decrease (P<0.05), and the ratio of type I to type III collagen decreased (P<0.05); ADRB2 mRNA levels significantly decreased (P<0.01), while MMP-1 and MMP-8 mRNA levels increased (P<0.01); the protein levels of TGF-β1 and Smad3 exhibited a significant decrease (P<0.05). Conclusions: ADRB2 knockdown reduced fibrosis during wound healing and degenerated connective tissue content around the wound bed by inhibiting the TGF-β1/Smad3 signaling pathway, which leads to an increase in MMP mRNA levels and a decrease in the ratio of type I to type III collagen.