肺纤维化鼠Ⅰ型前胶原和Ⅲ型前胶原mRNA表达及芪丹颗粒剂的干预效应

Effects of Qidan granule on the expression of precollagen Ⅰ and Ⅲ mRNA in pulmonary fibrosis rats

目的:观察芪丹颗粒对博莱霉素致肺纤维化鼠的Ⅰ型前胶原和Ⅲ型前胶原mRNA表达的影响,探讨其作用机制。方法:实验于2004-10/2006-10在山东省医学科学院基础所病理实验室完成。实验材料:清洁级雄性SD大鼠160只,体质量180～210g。氢化可的松琥珀酸钠50mg/支;芪丹(颗粒剂)是由黄芪、丹参、川芎等中草药加工提纯后的粗提取物制成的颗粒剂,10g/包(1g干粉相当于原生药8g)。实验分组:160只SD大鼠按随机区组设计分为正常组20只、模型组40只、芪丹颗粒剂50只、氢化可的松50只。实验干预:正常组20只气管内灌注和灌胃均用生理盐水。其余大鼠经气管内一次性灌注博莱霉素A5按0.25mL左右(5mg/kg体质量)诱导大鼠肺间质纤维化。随机取40只为模型组。取芪丹颗粒剂组和氢化可地松组大鼠各30只,分别从造模后第2天灌注芪丹颗粒剂(3125mg/kg)和腹腔注射氢化可的松(25mg/kg),药物干预后第7,14,28天麻醉下处死动物。两组各余20只分别从造模14d后灌注芪丹颗粒剂和腹腔注射氢化可的松(用量同前),于第28、42天分别处死动物。实验评估:用苏木精-伊红评价肺组织病理学变化和原位杂交方法检测各组大鼠肺Ⅰ型和Ⅲ型前胶原mRNA表达。结果:160只大鼠全部进入结果分析。①大鼠肺脏大体标本观察:对照组肺组织各观察时间点无明显改变,模型组肺组织表面凸凹不平,部分肺叶体积缩小,表面见灰白色结节。氢化可的松组与模型组相似。芪丹颗粒剂组见部分肺叶表面不光滑及大小不等结节。②肺组织病理学观察:模型组7d肺泡腔内大量巨噬细胞淋巴细胞中性粒细胞浸润,肺间质成纤维细胞增殖,28d肺泡结构破坏肺泡内见大量胶原纤维和成纤维细胞。芪丹颗粒剂组肺泡炎及肺纤维化程度均明显轻于模型组和氢化可的松组(P<0.05)。③肺间质纤维化形成中Ⅰ型、Ⅲ型前胶原mRNA表达:原位杂交显示两种前胶原mRNA表达呈动态变化,早期肺泡炎以Ⅲ型前胶原mRNA大量增生为主,晚期纤维化期以Ⅰ型前胶原mRNA增生为主。芪丹颗粒剂组Ⅲ型前胶原mRNA的表达在第14天处于最高,至28d仍维持较高的水平,芪丹颗粒剂组Ⅲ型前胶原mRNA的表达高于模型组和氢化可的松组(P<0.05)。28d,Ⅰ型前胶原mRNA的表达在第二天给药芪丹颗粒剂组和氢化可地松组及第14天给药芪丹颗粒剂组和氢化可的松组组间差异均有显著性(P<0.05)。结论:大鼠肺纤维化的早期以Ⅲ型前胶原mRNA的表达为主,晚期纤维化期以Ⅰ型前胶原mRNA的大量表达为主。芪丹颗粒可减轻博莱霉素诱导的大鼠肺泡炎及肺纤维化的程度,其机制可能通过影响了Ⅰ型和Ⅲ型前胶原mRNA的代谢和表达,从而减慢肺间质纤维化的进程。芪丹颗粒对肺间质纤维化有治疗作用,且优于氢化可的松。

AIM： To observe the effects of Qidan granule on the mRNA expression of type I precollagen and type Ⅲ precollagen in pulmonary fibrosis rats induced by bleomycin and explore its pathogenesis. METHODS： The experiment was performed at the Pathological Laboratory, Basic Institute, Shandong Academy of Medical Sciences from October 2004 to October 2006. Totally 160 male SD rats of clean grade with the body mass of 180-210 g were selected. There were each 50 mg hydrocortisoni and Qidan （granules） that were composed of crude extract of milkvetch root, salvia miltiorrhiza, szechwan Iovage rhizome and so on, 10 g/pack （1 g dry powder is equal to 8 g crude drug in whole）. Totally 160 SD rats were randomly divided into normal group （n =20）, model group （n =40）, Qidan granule group （n =50） and hydrocortisoni group （n =50）. Twenty rats in the control group were treated with saline water by intratracheal instillation and gastric perfusion. Pulmonary interstitial fibrosis was induced in rats by intratracheal instillation of about 0.25 mL bleomycin A5 （5 mg/kg body mass）. Forty rats were chosen as model group. Thirty rats of Qidan granule group and 30 rats of hydrocortisoni group received 3 125 mg/kg Qidan granule by gastric perfusion and 25 mg/kg hydrocortisone by intraperitoneal injection on the 2nd day after modeling, respectively. Rats were sacrificed at days 7, 14 and 28 after bleomycin. Twenty rats of Q/dan granule group and 20 rats of hydrocortisoni group received Qidan granule by gastric perfusion and hydrocortisone by intraperitoneal injection of the same volume 14 days after establishing models, respectively. Rats were sacrificed at days 28 and 42 after bleomycin. Histopathological changes of lung were evaluated by haematoxylin-eosin （HE） staining, and mRNA expression of type I precollagen and type Ⅲ precollagen in pulmonary fibrosis rats were detected by in situ hybridization. RESULTS： A total of 160 rats were involved in the result analysis.①General observation of lung of rats： There was no significant difference of pulmonary tissues on each time point in the control group and the surface of pulmonary tissues was uneven, partial pulmonary lobes contracted and gray node appeared in the model group. It was similar between the hydrocortisoni group and model group. The surface of partial pulmonary lobes was uneven and showed node of different sizes in the Qidan granule group.②Histopathological observation of lung： A mass of megalophages, leukomonocytes and neutrophile granulocytes infiltrated in alveolar space and pulmonary fibroblasts proliferated at day 7, and a mass of collagenous fibers and fibroblasts appeared in pulmonary alveoli at day 28 in the model group. Alveolar catarrh and pulmonary fibrosis were markedly milder in the Qidan granule group than the model group and hydrocortisoni group （P 〈 0.05）. ③mRNA expression of type I and Ⅲ precollagen in pulmonary fibrosis rats： in situ hybridization showed that the mRNA expression of two kinds of precollagen was dynamic change. The mRNA expression of type m precollagen mainly appeared in early alveolitis, whereas mRNA expression of type I precoUagen in late alveolitis. The mRNA expression of type Ⅲ precollagen reached the peak at day 14 and still maintained a high level at day 28 in the Qidan granule group. The mRNA expression of type m precollagen was higher in the Qidan granule group than the model group and hydrocortisoni group （P 〈 0.05）. At day 28, there were significant differences in mRNA expression of type I precollagen between the Q/dan granule group and hydrocortisoni group at days 2 and 14（P〈 0.05）. CONCLUSION： The mRNA expression of type Ⅲ precollagen mainly appeared in early alveolitis, whereas mRNA expression of type I precollagen in late alveolitis. Qidan granule can obviously reduce alveolitis and fibrosis induced by bleomycin. Qidan granules may alleviate the process of pulmonary fibrosis by influencing the expression of the mRNA expression of type I precollagen and type Ⅲ precollagen. The results strongly indicate the beneficial effects of Qidan granules in protecting lung against bleomycin-induced pulmonary fibrosis.