Research of heat shock protein 47 in lung fibtotic process

热休克蛋白(HSP)47作为胶原特异性分子伴侣参与了多种胶原蛋白的合成和组装。HSP47在肝硬变和其他纤维化疾病中的表达上调。本文研究了中性粒细胞天青颗粒中具有抗菌和细胞毒活性的阳离子蛋白α防御素对肺成纤维细胞产生热休克蛋白47和胶原的影响，以及热休克蛋白47的表达与肺纤维化过程的关系。首先，我们研究了α-防御素(人中性粒细胞多肽-1)对人肺成纤维细胞HSP47和胶原-1表达的直接影响。5μg/mlHNP-1诱导成纤维细胞增殖，50μg/mlHNP-1抑制细胞活力。当HNP-1浓度为10~25μg/ml时，HSP47和胶原-1mRNA的表达显著增加，蛋白释放量呈剂量依赖性增加。转化生长因子-β也促进了这些基因和蛋白的表达，而吡非尼酮抑制了这些结果。在博莱霉素诱导的小鼠肺纤维化模型中，肺纤维化程度与HSP47mRNA和蛋白的表达有良好的相关性，吡非尼酮可降低Ashcroft评分和羟脯氨酸含量。免疫组织化学研究还可降低肺细胞HSP47、α-SMA和F4/80的表达。提示α-防御素可能通过上调HSP47和胶原-1的表达，直接促进肺成纤维细胞的纤维化进程，在肺纤维化的发病机制中起重要作用，HSP47阳性细胞可能具有促进胶原合成和释放的能力。吡非尼酮抑制这些阳性细胞，这些阳性细胞负责肺纤维化中细胞外基质的积累和沉积。这些发现表明，HSP47和α-防御素可能成为治疗特发性肺纤维化的新靶点。

Heat shock protein(HSP) 47 is involved in the synthesis/assembly of various collagens as a collagen-specific molecular chaperone. HSP 47 expression has been shown upregulated in liver cirrhosis and other fibrotic diseases. We have studied the effect of α-defensin, cationic proteins with antimicrobial and cytotoxic activity in the azurophil granule of neutrophils, on the production of HSP 47 and collagen using lung fibroblasts, and the relationship between HSP47 expression and fibrotic process in murine bleomycin-induced pulmonary fibrosis. At first, we investigated the direct effect of a-defensin (human neutrophil peptide(HNP)-1) on expression of HSP47 and collagen-1 in human lung fibroblasts. HNP-1 5 μg/ml induced fibroblast proliferation and concentrations >50 μg/ml of HNP-1 reduced the cell-viability. Expression of HSP 47 and collagen-1 mRNA was significantly increased by 10 to 25 μg/ml of HNP-1, whereas their protein release increased in dose-dependent manner. TGF-β also enhanced the expression of these mRNA and proteins, and pirfenidone inhibited these findings. In murine bleomycin-induced pulmonary fibrosis, a good correlation was also observed between the degree og pulmonary fibrosis and expression of HSP47 mRNA and proteins and pirfenidone reduced the ashcroft score and hydroxyproline content. It also attenuated expression of HSP 47, a-SMA and F4/80 in lung cells by immunohistochemical study. Our results suggest that α-defensin may promote directly fibrotic process through upregulation of HSP 47 and collagen-1 in human lung fibroblasts and play an important role in the pathogenesis of pulmonary fibrosis and HSP47 positive cells may have an ability of enhanced collagen synthesis and release. Pirfenidone inhibited these positive cells responsible for the accumulation and deposition of extracellular matrix seen in pulmonary fibrosis. These findings suggest that HSP47 and α-defensin might be a new promising target for the treatment of IPF.