白细胞介素-33在实验性肺纤维化大鼠肺内的表达

Dynamic changes of interleukin-33 expression in bleomycin-induced pulmonary fibrosis in rats

目的观测白细胞介素-33（interleukin，IL-33）在博莱霉素（BLM）所致大鼠肺纤维化模型中的表达。方法健康雌性SD大鼠60只，随机分两组，每组30只。实验组：气管内一次性注入生理盐水稀释的BLM（5mg／kg）；对照组：气管内注入生理盐水（0．2±0．3mL）。于给药后第1、3、7、14和28天用过量氯胺酮腹腔注射的方法随机处死实验组及对照组大鼠各6只。无菌操作下取出大鼠肺组织，RT—PCR法检测肺组织中IL-33mRNA表达，免疫荧光法检测肺组织IL-33蛋白的表达及定位。结果肺纤维化模型复制成功；IL-33基因表达相对灰度值在造模后不同时期与对照组比较差异有显著性（P〈0．01），各个时期之间比较差异有显著性（P〈0．01）。在肺纤维化形成过程中，实验组中的IL-33的基因和蛋白表达呈现出如下趋势：自BLM注入后第1天开始迅速升高，至第7天到达高峰，以后逐渐下降，但第28天仍高于正常。在对照组仅在肺泡上皮细胞有少量表达，在纤维化大鼠肺组织的肺泡上皮细胞中表达显著增高，在炎症细胞中的表达增加，特别在成纤维细胞灶内更明显，但在已形成纤维化的肺组织中表达有所下降。结论IL-33是肺纤维化过程中的前炎症因子，在纤维化的发生、发展的病理过程中起重要作用，检测IL-33的水平对肺纤维化的早期诊断有显著帮助。

[ Objective ] To observe the expression of IL-33 in bleomycin-induced pulmonary fibrosis in rats to discuss its possible role in the pathogenesis of pulmonary fibrosis. [ Methods ] The 60 female SD rats were random- ly divided into two groups （each of 30）. Group one received intratraeheal instillation of single dose bleomycin A5 （BLM） 5 mg/kg and group two received normal saline. On day 1, 3, 7, 14, 28 after administration, 6 rats of each group were sacrificed and the lung tissues were harvested respectively. Immunofluoreseence was performed to inves- tigate the expression of IL-33 protein in the lung. RT-PCR examined the expression of IL-33 mRNA. [Results] Only the bronchial epithelial cells were positive for IL-33 in the control rat. In addition to bronchial epithelial cells, inflammatory cells were predominately positive for IL-33 after the BLM challenge, especially in the fibroblastic loci （FF）. The expression of IL-33 mRNA significantly increased rapidly from day 1, reached peak on day 7, than de- creased gradually and still more than normal level on day 28 （vs. control, P 〈0.0l）, as well as the expression of IL- 33 protein. [ Conclusion] The proinflammatory cytokine IL-33 plays an important role in the lung pathology of pul- monary fibrosis. Detection of IL-33 is helpful to early diagnosis of pulmonary fibrosis.