博莱霉素致大鼠肺纤维化及与肺血管内皮细胞损伤的关系

目的 探讨血管内皮损伤与博莱霉素(BLM)致大鼠肺纤维化发生间的关系。方法 实验组大鼠经气管灌注BLM制作肺纤维化模型,采用免疫组化及图像分析系统对其肺组织中血管内皮细胞生长因子(VEGF)进行定性、定量分析。结果 (1)组织学观察:染BLM后3、7 d,大鼠肺泡腔及间隔水肿,炎细胞渗出,肺泡Ⅰ型及Ⅱ型上皮细胞变性、坏死,肺泡上皮细胞基底膜断裂,血管内皮细胞肿胀,核浓缩;7、14 d,大鼠肺泡Ⅱ型上皮细胞增生,肺泡间隔有较多成纤维细胞及新生毛细血管形成;28 d,大鼠肺泡间隔增厚,肺泡结构破坏,肺组织明显纤维化样改变。(2)VEGF免疫组化染色:对照组大鼠肺组织呈弱表达,主要分布于肺泡Ⅱ型上皮细胞、支气管黏膜上皮细胞、肺泡巨噬细胞及肺间质细胞。染BLM组大鼠VEGF呈明显高表达,其中,3 d至28 d,大鼠肺泡Ⅱ型上皮细胞VEGF持续高表达,表达量明显高于对照组,差异有统计学意义(P<0.05,P<0.01);7、14、28 d,大鼠肺间质细胞VEGF呈高表达;3 d至28 d,大鼠肺泡巨噬细胞VEGF表达均升高,与对照组的差异均有统计学意义(P<0.05,P<0.01)。结论 VEGF持续高表达与大鼠血管内皮细胞损伤有关,而血管内皮细胞的损伤可能是BLM诱发大鼠肺纤维化的重要启动因素之一。

Relationship between bleomycin-induced pulmonary fibrosis and vascular endothelial cell injury

OBJECTIVE: To explore the relationship between the injury of vascular endothelial cells and formation of lung fibrosis by bleomycin (BLM) in rats. METHODS: The rats of experimental groups were treated with bleomycin intratracheally to induce pulmonary fibrosis. The expression of vascular endothelial growth factor (VEGF) in pulmonary tissues were analyzed qualitatively and quantitatively by immunohistochemistry and image analysis system. RESULTS: (1) Histology: Edema in rat alveoli and alveolar septum, inflammatory cells exudation, degeneration and necrosis of type I and type II alveolar epithelial cells (AETI and AETII), ruptured alveolar basement membrane, as well as swollen vascular endothelial cells and karyopyknosis were observed in 3 d and 7 d after treatment with BLM. AETII proliferation, with more fibroblasts in alveolar septum, and new capillary vessel formation in 7, 14 d, as well as thickened alveolar septum, damaged alveolar structure, and obvious pulmonary tissue fibrosis in 28 d after treatment with BLM were observed. (2) Immunohistochemistry: in normal control, VEGF expressed weakly in pulmonary tissue distributing mainly in AETII, bronchial epithelial cells, alveolar macrophages and leydig's cells. While in bleomycin treated groups, the expression of VEGF increased markedly. The expression in AETII, and pulmonary macrophage were significantly higher than that in control in 3 d to 28 d (P < 0.05, P < 0.01). The rat leydig's cells also had higher expression of VEGF in 7, 14, 28 d (P < 0.05, P < 0.01). CONCLUSION: The high expression of VEGF is related to vascular endothelial cells injury which may be one of important factors in the formation of bleomycin-induced pulmonary fibrosis.