Functional analysis of lipid mediators in pulmonary fibrosis

背景：肺纤维化是肺实质间质性疾病，其发病机制尚不清楚。已知前列腺素参与纤维形成过程，由肺内各种细胞产生，如巨噬细胞、上皮细胞、内皮细胞、平滑肌细胞、成纤维细胞等，参与肺纤维化的发病机制。我们假设抗纤维化（前列腺素I2 [PGI2]）或促纤维化（血栓素[TX]A2）前列腺素（pg）合成酶的气管内基因转移可改变肺纤维化的严重程度。方法：将含人PGIS基因的1.6-BamHI片段和含人TXAS基因的1.8-kb BamHI片段连接到pCI-neo表达载体上，分别命名为pCI-PGIS和pCI-TXAS。我们在6-8周龄的C57BL/6小鼠气管内注射含有20 mcg pCI-PGIS或pCI-TXAS的hvj脂质体复合物。基因转移后24小时气管内给予60 mcg布霉素，每天观察，处死右肺组织学研究和左肺羟脯氨酸测定。结果：PGIS基因转染后大鼠体重增加（157%，第21天，与无载体对照相比，p<0.05），肺羟脯氨酸含量降低（75%，第14天，与无载体对照相比，p<0.05），肺细胞浸润减少，而TXAS基因转染则呈现相反的效果。结论：这些结果提示抗纤维化和促纤维化pg的平衡可能是肺纤维化严重程度的决定因素。抗纤维化或促纤维化pg可能是治疗肺纤维化新疗法的分子靶点。

BACKGROUND : Pulmonary fibrosis is an interstitial disorder of the lung parenchyma, of which mechanism is poorly understood. Prostanoids are known to participate in the process of fibrogenesis and produced by various cells in the lung, such as macrophages, epithelial cells, endothelial cells, smooth muscle cells, and fibroblasts, which are involved in the pathogenesis of pulmonary fibrosis. We hypothesized that intratracheal gene transfer of a synthase of anti-fibrotic (prostaglandin I2 [PGI2]) or pro-fibrotic (thromboxane [TX]A2) prostaglandins (PGs) alters severity of lung fibrosis. METHODS : A 1.6-BamHI fragment containing human PGIS gene or a 1.8-kb BamHI fragment containing human TXAS gene was ligated into pCI-neo expression vector, and designated pCI-PGIS and pCI-TXAS, respectively. We injected HVJ-liposome complex including 20 mcg of pCI-PGIS or pCI-TXAS into tracheas of C57BL/6 mice at age of 6-8 weeks. The animals were administered with 60 mcg of bloemycin intratracheally 24 hours after gene transfer, observed daily, and sacrificed for histological study of right lungs and hydroxyproline assay of left lungs. RESULTS : The gene transfer of PGIS increased body weight (157%, day 21, vs null-vector control ; p<0.05), decreased hydroxyproline content in the lung (75%, day 14, vs null-vector control ; p<0.05) and decreased cell infiltration in the lung, whereas TXAS gene transfer tended to present opposite effects. CONCLUSION : These results suggest that a balance of antifibrotic and profibrotic PGs might be a determinant of severity of lung fibrosis. The anti-fibrotic or pro-fibrotic PGs might be molecular targets for new therapies to treat pulmonary fibrosis.