纤溶酶原激活物抑制剂1 siRNA对大鼠肺纤维化的治疗作用

 目的： 观察纤溶酶原激活物抑制剂1 （PAI-1）siRNA对博来霉素(BLM)诱导的大鼠肺纤维化的治疗作用，并初步探讨其机制。方法： 72只Wister大鼠分为4组，即对照组（control组）、BLM组、BLM+非特异 siRNA 组(BLM+N组)和BLM+PAI-1 siRNA组(BLM+P组)。BLM 5 mg/kg气管内滴入制作肺纤维化模型，control组注入等体积的生理盐水。造模后，于局麻下BLM+P组每周2次气管内注入PAI-1 siRNA 7.5 nmol (0.2 mL)；BLM+N组注入相同剂量的非特异siRNA；control组和BLM组注入等体积的生理盐水，28 d共给药8次。分别于第7 d、14 d和28 d每组处死6只,左肺行肺泡灌洗测定PAI-1活性，右中叶肺组织RT-PCR法检测Ⅲ型胶原、α-平滑肌肌动蛋白（α-SMA）和金属蛋白酶组织抑制物1（TIMP-1）的mRNA表达。结果： 造模后，7 d、14 d和28 d肺泡灌洗液中PAI-1活性持续升高，每周2次气管内注入PAI-1 siRNA可以使肺泡灌洗液中PAI-1的活性降低，与同一时点BLM组比较有明显差异（均P<0.05）；模型组7 d、14 d和28 d  Ⅲ型胶原、α-SMA和TIMP-1的mRNA表达明显增高，BLM+P组3个时点Ⅲ型胶原、α-SMA和TIMP-1的mRNA表达明显减少，分别与同一时点BLM组比较有明显差异（均P<0.05）。结论： 每周2次气管内给予PAI-1 siRNA可以持续减少PAI-1表达。PAI-1 siRNA不但直接抑制肺纤维化进展，而且可以打破基质金属蛋白酶及组织抑制因子之间的平衡。

Inhibition of plasminogen activator inhibitor-1 by small interfering RNA attenuates pulmonary fibrosis in rats

AIM: To examine the effects of silencing of plasminogen activator inhibitor-1 (PAI-1) expression by small interfering RNA (siRNA) on bleomycin (BLM)-induced rat pulmonary fibrosis. METHODS: Total 72 Wistar rats were divided into 4 groups: control, BLM, BLM+non-specific siRNA (BLM+N), and BLM+ PAI-1 siRNA (BLM+P). Pulmonary fibrosis was induced by intratracheal injection of BLM (5 mg/kg), whereas equal volume of normal saline was used in control group. After the administration of BLM or normal saline, the rats were treated with tracheal injection of PAI-1-siRNA (7.5 nmol/0.2 mL per rat) in BLM+P group, non-specific siRNA (7.5 nmol/0.2 mL per rat) in BLM+N group, and 0.2 mL normal saline in BLM group and control group, twice a week, 8 times in 28 d. On day 7, 14, and 28, the rats (n=6 at each time point) were sacrificed. The bronchoalveolar lavage fluid (BALF) from the left lung was harvested to examine the activity of PAI-1. The mRNA expression of collagen type Ⅲ, α-smooth muscle actin (α-SMA) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in the middle lobe of the right lung was detected by RT-PCR. RESULTS: PAI-1 activity and the expression of collagen type Ⅲ, α-SMA and TIMP-1 were increased in BLM group on day 7, 14 and 28. Intratracheal injection of PAI-1 siRNA twice a week continuously reduced PAI-1 activity in the BALF (P<0.05),and decreased the expression of collagen type Ⅲ, α-SMA and TIMP-1 in the fibrotic lung tissues on day 7, 14 and 28. Statistical differences in the expression of collagen type Ⅲ, α-SMA and TIMP-1 between BLM+P group and BLM group at the same time point were observed. CONCLUSION: Intratracheal injection of PAI-1 siRNA twice a week continuously inhibits the expression of PAI-1. PAI-1 siRNA ameliorates BLM-induced pulmonary fibrosis by down-regulation of TIMP-1 expression.