Binks Andrew P, Beyer Megyn, Miller Ryan, LeClair Renee J
Department of Biomedical Sciences, School of Medicine, Greenville, University of South Carolina, Greenville, South Carolina.
Department of Biomedical Sciences, College of Osteopathic Medicine, University of New England, Biddeford, Maine.
Physiol Rep. 2017 Mar;5(5). doi: 10.14814/phy2.13115.
Idiopathic pulmonary fibrosis (IPF) involves collagen deposition that results in a progressive decline in lung function. This process involves activation of Smad2/3 by transforming growth factor (TGF)- and Wnt signaling pathways. Collagen Triple Helix Repeat-Containing-1 (Cthrc1) protein inhibits Smad2/3 activation. To test the hypothesis that Cthrc1 limits collagen deposition and the decline of lung function, Cthrc1 knockout (Cthrc1) and wild-type mice (WT) received intratracheal injections of 2.5 U/kg bleomycin or saline. Lungs were harvested after 14 days and Bronchoalveolar lavage (BAL) TGF-, IL1-, hydroxyproline and lung compliance were assessed. TGF- was significantly higher in Cthrc1 compared to WT (53.45 ± 6.15 ng/mL vs. 34.48 ± 11.05) after saline injection. Bleomycin injection increased TGF- in both Cthrc1 (66.37 ± 8.54 ng/mL) and WT (63.64 ± 8.09 ng/mL). Hydroxyproline was significantly higher in Cthrc1 compared to WT after bleomycin-injection (2.676 ± 0.527 g/mg vs. 1.889 ± 0.520, = 0.028). Immunohistochemistry of Cthrc1 lung sections showed intracellular localization and activation of -catenin Y654 in areas of tissue remodeling that was not evident in WT Lung compliance was significantly reduced by bleomycin in Cthrc1 but there was no effect in WT animals. These data suggest Cthrc1 reduces fibrotic tissue formation in bleomycin-induced lung fibrosis and the effect is potent enough to limit the decline in lung function. We conclude that Cthrc1 plays a protective role, limiting collagen deposition and could form the basis of a novel therapy for pulmonary fibrosis.
特发性肺纤维化（IPF）涉及胶原蛋白沉积，导致肺功能进行性下降。这一过程涉及转化生长因子（TGF）-β和Wnt信号通路对Smad2/3的激活。含胶原蛋白三螺旋重复序列-1（Cthrc1）蛋白可抑制Smad2/3的激活。为了验证Cthrc1限制胶原蛋白沉积和肺功能下降这一假说，将Cthrc1基因敲除小鼠（Cthrc1-/-）和野生型小鼠（WT）经气管内注射2.5 U/kg博来霉素或生理盐水。14天后采集肺组织，并评估支气管肺泡灌洗（BAL）液中的TGF-β、白细胞介素-1（IL-1）、羟脯氨酸和肺顺应性。注射生理盐水后，Cthrc1-/-小鼠BAL液中的TGF-β显著高于WT小鼠（53.45±6.15 ng/mL对34.48±11.05 ng/mL）。注射博来霉素后，Cthrc1-/-小鼠（66.37±8.54 ng/mL）和WT小鼠（63.64±8.09 ng/mL）的TGF-β均升高。注射博来霉素后，Cthrc1-/-小鼠的羟脯氨酸显著高于WT小鼠（2.676±0.527 μg/mg对1.889±0.520 μg/mg，P = 0.028）。Cthrc1-/-小鼠肺组织切片的免疫组织化学显示，在组织重塑区域，β-连环蛋白Y654呈细胞内定位并被激活，而WT小鼠肺组织中未观察到这一现象。博来霉素显著降低了Cthrc1-/-小鼠的肺顺应性，但对WT小鼠无影响。这些数据表明，Cthrc1可减少博来霉素诱导的肺纤维化中的纤维化组织形成，且该作用足以限制肺功能下降。我们得出结论，Cthrc1发挥保护作用，限制胶原蛋白沉积，可能成为肺纤维化新疗法的基础。
