1 Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas (INER), Mexico City, Mexico.
2 Cátedra Consejo Nacional de Ciencia y Tecnología (CONACyT)-INER, Mexico City, Mexico.
Am J Respir Cell Mol Biol. 2018 Jul;59(1):65-76. doi: 10.1165/rcmb.2017-0115OC.
Idiopathic pulmonary fibrosis (IPF) is characterized by the expansion of the myofibroblast population, excessive extracellular matrix accumulation, and destruction of the lung parenchyma. The R-spondin family (RSPO) comprises a group of proteins essential for development. Among them, RSPO2 is expressed primarily in the lungs, and its mutations cause severe defects in the respiratory tract. Interestingly, RSPO2 participates in the canonical Wingless/int1 pathway, a critical route in the pathogenesis of IPF. Thus, the aim of this study was to examine the expression and putative role of RSPO2 in this disease. We found that RSPO2 and its receptor leucine-rich G protein-coupled receptor 6 were upregulated in IPF lungs, where they localized primarily in fibroblasts and epithelial cells. Stimulation of IPF and normal lung fibroblasts with recombinant human RSPO2 resulted in the deregulation of numerous genes, although the transcriptional response was essentially distinct. In IPF fibroblasts, RSPO2 stimulation induced the up- or downregulation of several genes involved in the Wingless/int1 pathway (mainly from noncanonical signaling). In both normal and IPF fibroblasts, RSPO2 modifies the expression of genes implicated in several pathways, including the cell cycle and apoptosis. In accordance with gene expression, the stimulation of normal and IPF fibroblasts with RSPO2 significantly reduced cell proliferation and induced cell death. RSPO2 also inhibited collagen production and increased the expression of matrix metalloproteinase 1. Silencing RSPO2 with shRNA induced the opposite effects. Our findings demonstrate, for the first time to our knowledge, that RSPO2 is upregulated in IPF, where it appears to have an antifibrotic role.
特发性肺纤维化 (IPF) 的特征是成纤维细胞(myofibroblast)数量增加、细胞外基质过度积累和肺实质破坏。RSPO 家族(R-spondin family)由一组对发育至关重要的蛋白质组成。其中,RSPO2 主要在肺部表达,其突变导致呼吸道严重缺陷。有趣的是,RSPO2 参与了经典的 Wnt/int1 通路,这是 IPF 发病机制中的一个关键途径。因此,本研究旨在研究 RSPO2 在这种疾病中的表达和潜在作用。我们发现 RSPO2 及其受体富含亮氨酸的 G 蛋白偶联受体 6 在 IPF 肺中上调,主要定位于成纤维细胞和上皮细胞中。用重组人 RSPO2 刺激 IPF 和正常肺成纤维细胞导致许多基因的失调,尽管转录反应基本上是不同的。在 IPF 成纤维细胞中,RSPO2 刺激诱导了几个参与 Wnt/int1 途径的基因的上调或下调(主要来自非经典信号)。在正常和 IPF 成纤维细胞中,RSPO2 改变了几个涉及细胞周期和凋亡的基因的表达。与基因表达一致,RSPO2 刺激正常和 IPF 成纤维细胞显著降低细胞增殖并诱导细胞死亡。RSPO2 还抑制胶原蛋白的产生并增加基质金属蛋白酶 1 的表达。用 shRNA 沉默 RSPO2 诱导了相反的效果。我们的研究结果首次表明,RSPO2 在 IPF 中上调,在 IPF 中似乎具有抗纤维化作用。