Laboratorio de Biología Celular, Departamento de Fibrosis Pulmonar, Instituto Nacional de Enfermedades Respiratorias "Ismael Cosío Villegas", Ciudad de México 14080, Mexico.
Laboratorio de Investigación en Enfermedades Reumáticas, Instituto Nacional de Enfermedades Respiratorias "Ismael Cosío Villegas", Ciudad de México 14080, Mexico.
Int J Mol Sci. 2021 Jul 23;22(15):7870. doi: 10.3390/ijms22157870.
Idiopathic pulmonary fibrosis (IPF) is a devastating disease characterized by increased activation of fibroblasts/myofibroblasts. Previous reports have shown that IPF fibroblasts are resistant to apoptosis, but the mechanisms remain unclear. Since inhibition of the mitochondrial permeability transition pore (mPTP) has been implicated in the resistance to apoptosis, in this study, we analyzed the role of mitochondrial function and the mPTP on the apoptosis resistance of IPF fibroblasts under basal conditions and after mitomycin C-induced apoptosis. We measured the release of cytochrome c, mPTP opening, mitochondrial calcium release, oxygen consumption, mitochondrial membrane potential, ADP/ATP ratio, ATP concentration, and mitochondrial morphology. We found that IPF fibroblasts were resistant to mitomycin C-induced apoptosis and that calcium, a well-established activator of mPTP, is decreased as well as the release of pro-apoptotic proteins such as cytochrome c. Likewise, IPF fibroblasts showed decreased mitochondrial function, while mPTP was less sensitive to ionomycin-induced opening. Although IPF fibroblasts did not present changes in the mitochondrial membrane potential, we found a fragmented mitochondrial network with scarce, thinned, and disordered mitochondria with reduced ATP levels. Our findings demonstrate that IPF fibroblasts are resistant to mitomycin C-induced apoptosis and that altered mPTP opening contributes to this resistance. In addition, IPF fibroblasts show mitochondrial dysfunction evidenced by a decrease in respiratory parameters.
特发性肺纤维化（IPF）是一种破坏性疾病，其特征在于成纤维细胞/肌成纤维细胞的过度激活。先前的报告表明，IPF 成纤维细胞对细胞凋亡具有抗性，但机制尚不清楚。由于抑制线粒体通透性转换孔（mPTP）与细胞凋亡的抗性有关，因此在这项研究中，我们分析了在基础条件下和丝裂霉素 C 诱导细胞凋亡后，线粒体功能和 mPTP 对 IPF 成纤维细胞抗凋亡的作用。我们测量了细胞色素 c 的释放、mPTP 的开放、线粒体钙释放、耗氧量、线粒体膜电位、ADP/ATP 比、ATP 浓度和线粒体形态。我们发现，IPF 成纤维细胞对丝裂霉素 C 诱导的细胞凋亡具有抗性，钙作为 mPTP 的一种已确立的激活剂，其释放以及细胞色素 c 等促凋亡蛋白的释放减少。同样，IPF 成纤维细胞表现出线粒体功能降低，而 mPTP 对离子霉素诱导的开放不太敏感。尽管 IPF 成纤维细胞的线粒体膜电位没有变化，但我们发现线粒体网络呈碎片化，线粒体稀少、变薄且排列紊乱，ATP 水平降低。我们的研究结果表明，IPF 成纤维细胞对丝裂霉素 C 诱导的细胞凋亡具有抗性，并且改变的 mPTP 开放有助于这种抗性。此外，IPF 成纤维细胞表现出线粒体功能障碍的证据，表现为呼吸参数下降。
