1] INSERM, U1148-LVTS, F-75018 Paris, France, Université Paris Diderot, Sorbonne Paris Cité, Paris, France [2] DHU FIRE, Paris, France.
1] DHU FIRE, Paris, France [2] INSERM, U1152, F-75018 Paris, France, Université Paris Diderot, Sorbonne Paris Cité, Paris, France.
Lab Invest. 2014 Nov;94(11):1237-46. doi: 10.1038/labinvest.2014.111. Epub 2014 Sep 8.
Idiopathic pulmonary fibrosis (IPF) is a chronic diffuse lung disease characterized by an accumulation of excess fibrous material in the lung. Protease nexin-1 (PN-1) is a tissue serpin produced by many cell types, including lung fibroblasts. PN-1 is capable of regulating proteases of both coagulation and fibrinolysis systems, by inhibiting, respectively, thrombin and plasminergic enzymes. PN-1 is thus a good candidate for regulating tissue remodeling occurring during IPF. We demonstrated a significant increase of PN-1 expression in lung tissue extracts, lung fibroblasts and bronchoalveolar lavage fluids of patients with IPF. The increase of PN-1 expression was reproduced after stimulation of control lung fibroblasts by transforming growth factor-β, a major pro-fibrotic cytokine involved in IPF. Another serpin, plasminogen activator inhibitor-1 (PAI-1) is also overexpressed in fibrotic fibroblasts. Unlike PAI-1, cell-bound PN-1 as well as secreted PN-1 from IPF and stimulated fibroblasts were shown to inhibit efficiently thrombin activity, indicating that both serpins should exhibit complementary roles in IPF pathogenesis, via their different preferential antiprotease activities. Moreover, we observed that overexpression of PN-1 induced by transfection of control fibroblasts led to increased fibronectin expression, whereas PN-1 silencing induced in fibrotic fibroblasts led to decreased fibronectin expression. Overexpression of PN-1 lacking either its antiprotease activity or its binding capacity to glycosaminoglycans had no effect on fibronectin expression. These novel findings suggest that modulation of PN-1 expression in lung fibroblasts may also have a role in the development of IPF by directly influencing the expression of extracellular matrix proteins. Our data provide new insights into the role of PN-1 in the poorly understood pathological processes involved in IPF and could therefore give rise to new therapeutic approaches.
特发性肺纤维化（IPF）是一种慢性弥漫性肺部疾病，其特征是肺部积聚过多的纤维物质。蛋白酶抑制剂-1（PN-1）是一种组织丝氨酸蛋白酶，由许多细胞类型产生，包括肺成纤维细胞。PN-1 能够通过抑制凝血酶和纤溶酶酶分别调节凝血和纤溶系统的蛋白酶。因此，PN-1 是调节 IPF 中发生的组织重塑的良好候选物。我们在 IPF 患者的肺组织提取物、肺成纤维细胞和支气管肺泡灌洗液中证明了 PN-1 表达的显著增加。在转化生长因子-β刺激对照肺成纤维细胞后，PN-1 的表达增加，转化生长因子-β是一种涉及 IPF 的主要促纤维化细胞因子。另一种丝氨酸蛋白酶抑制剂-1（PAI-1）也在纤维化成纤维细胞中过度表达。与 PAI-1 不同，细胞结合的 PN-1 以及从 IPF 和刺激的成纤维细胞中分泌的 PN-1 被证明能有效地抑制凝血酶活性，这表明两种丝氨酸蛋白酶抑制剂应该通过其不同的抗蛋白酶活性在 IPF 发病机制中发挥互补作用。此外，我们观察到转染对照成纤维细胞导致 PN-1 过表达会引起纤连蛋白表达增加，而纤维化成纤维细胞中 PN-1 沉默会导致纤连蛋白表达减少。缺乏抗蛋白酶活性或与糖胺聚糖结合能力的 PN-1 过表达对纤连蛋白表达没有影响。这些新发现表明，肺成纤维细胞中 PN-1 表达的调节可能通过直接影响细胞外基质蛋白的表达，在 IPF 的发展中也具有作用。我们的数据为 PN-1 在 IPF 中涉及的理解甚少的病理过程中的作用提供了新的见解，并可能由此产生新的治疗方法。
