Clostridioides (formerly Clostridium) difficile infection is the leading cause of antibiotic-associated colitis. Studies have demonstrated that C. difficile toxin A (TcdA) can cause apoptosis of many human cell types. The purpose of this study was to investigate the relationships among exposure to TcdA, the role of the receptor for the globular heads of C1q (gC1qR) gene and the underlying intracellular apoptotic mechanism in human colonic epithelial cells (NCM 460). In this study, gC1qR expression was examined using real-time polymerase chain reaction (PCR), western blotting and immunohistochemical staining. Cell viability was assessed by the water-soluble tetrazolium salt (WST-1) assay, and cell apoptosis was assessed by flow cytometry and the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) assay. Mitochondrial function was assessed based on reactive oxygen species (ROS) generation, changes in the mitochondrial membrane potential (ΔΨm) and the content of ATP. Our study demonstrated that increasing the concentration of TcdA from 10 ng/ml to 20 ng/ml inhibited cell viability and induced cell apoptosis (p < 0.01). Moreover, the TcdA-induced gC1qR expression and enhanced expression of gC1qR caused mitochondrial dysfunction (including production of ROS and decreases in the ΔΨm and the content of ATP) and cell apoptosis. However, silencing of the gC1qR gene reversed TcdA-induced cell apoptosis and mitochondrial dysfunction. These data support a mechanism by which gC1qR plays a crucial role in TcdA-induced apoptosis of human colonic epithelial cells in a mitochondria-dependent manner.

中文翻译：

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C1q 受体球状头在 TcdA 诱导的人结肠上皮细胞凋亡中的作用，通过线粒体依赖性途径。

艰难梭菌感染是抗生素相关性结肠炎的主要原因。研究表明，艰难梭菌毒素 A (TcdA) 可导致许多人类细胞类型的细胞凋亡。本研究的目的是研究 TcdA 暴露、C1q 球状头受体 (gC1qR) 基因的作用以及人结肠上皮细胞 (NCM 460) 中潜在的细胞内凋亡机制之间的关系。在这项研究中，使用实时聚合酶链反应 (PCR)、蛋白质印迹和免疫组织化学染色检查了 gC1qR 的表达。通过水溶性四唑盐 (WST-1) 测定评估细胞活力，并通过流式细胞术和末端脱氧核苷酸转移酶介导的脱氧尿苷三磷酸缺口末端标记 (TUNEL) 测定评估细胞凋亡。基于活性氧 (ROS) 的产生、线粒体膜电位 (ΔΨm) 的变化和 ATP 含量评估线粒体功能。我们的研究表明，将 TcdA 的浓度从 10 ng/ml 增加到 20 ng/ml 会抑制细胞活力并诱导细胞凋亡（p < 0.01）。此外，TcdA 诱导的 gC1qR 表达和 gC1qR 的增强表达导致线粒体功能障碍（包括 ROS 的产生和 ΔΨm 和 ATP 含量的降低）和细胞凋亡。然而，gC1qR 基因的沉默逆转了 TcdA 诱导的细胞凋亡和线粒体功能障碍。这些数据支持 gC1qR 在 TcdA 诱导的人结肠上皮细胞凋亡中以线粒体依赖性方式发挥关键作用的机制。