Molecular biological analysis of bradykinin B1 receptor in chronic inflammatory pulmonary diseases.

为了探讨激肽-钾素系统在慢性炎性肺疾病中的作用，我们在体外和离体研究了缓激肽B1受体的分子生物学功能。缓激肽受体有B1和B2两种亚型，分别是- arg ^9-缓激肽和- arg ^10-kallidin的诱导受体和构成受体，以及缓激肽和kallidin的B1和B2受体激动剂。首先，我们对小鼠肺泡巨噬细胞系MH-S中的小鼠B1受体进行了表征。促炎细胞因子白细胞介素-1__。β(IL 1 __。β)诱导小鼠B1受体基因表达，B1激动剂通过IL-1__刺激肿瘤坏死因子α (TNF-α)的产生。β预处理的MH-S细胞。然后我们对人肺成纤维细胞系IMR-90中人Bl受体进行了表征。IL-1__。通过实时定量RT-PCR检测β诱导人Bl受体基因表达，而Bl激动剂刺激IMR-90细胞产生细胞外基质纤维连接蛋白。用Bl受体激动剂刺激IL-1__。β-预处理的IMR-90细胞比IL-1__产生的纤维连接蛋白少。β-未处理的IMR-90细胞。这种有趣的现象被环加氧酶（COX）抑制剂吲哚美辛和NS-398逆转，它们分别是COX1/COX-2双重抑制剂和选择性COX-2抑制剂。此外，特发性肺纤维化患者肺组织中B1受体基因表达较对照组降低。提示激肽-钾likrein系统联合诱导型COX-2通过激活B1受体保护肺纤维化，在慢性炎性肺疾病中发挥一定作用。由于B1受体基因在其他疾病中也存在一定的多态性，因此在慢性炎性肺疾病尤其是特发性肺纤维化中也需要进一步的研究。

To investigate the role of kinin-kallikein system in chronic inflammatory pulmonary diseases, we studied the molecular biological function of bradykinin B1 receptor in vitro and ex vivo. Bradykinin receptor has two subtypes B1 and B2, which are inducible and constitutive receptors for des-Arg^9-bradykinin and des-Arg^10-kallidin and for bradykinin and kallidin, B1 and B2 receptor agonists, respectively. First we characterized murine B1 receptor in a murine alveolar macrophage cell line MH-S. Pro-inflammatory cytokine interleukin-1__.β(IL -1__.β)induced murine B1 receptor gene expression assessed by quantitative real time RT-PCR, and B1 agonist stimulated the production of tumor necrosis factor alpha (TNF-α) by IL-1__.β-pretreated MH-S cells. Then we characterized human Bl receptor in human lung fibroblast cell line IMR-90. IL-1__.βinduced human Bl receptor gene expression assessed by quantitative real time RT-PCR, and Bl agonist stimulated the production of extracellular matrix fibronectin by IMR-90 cells. With Bl receptor agonist stimulation IL-1__.β-pretreated IMR-90 cells produced less fibronectin than that of IL-1__.β-untreated IMR-90 cells. This interesting phenomenon was reversed by cyclooxygenase (COX) inhibitors indomethacin and NS-398, the dual COX1/COX-2 inhibitor and selective COX-2 inhibitor, respectively. Furthermore, there was a decrease in the gene expression of B1 receptor in the lung tissue of idiopathic pulmonary fibrosis patients compared to the control. These results suggest that kinin-kallikrein system play some role in the chronic inflammatory pulmonary diseases via B1 receptor activation to protect lung fibrosis in combination with inducible COX-2. Because there are some polymorphisms in B1 receptor gene in other diseases, further investigation would be needed in chronic inflammatory pulmonary diseases as well especially in idiopathic pulmonary fibrosis.