Heilongjiang Provincial Key Laboratory of Zoonosis, College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang, China.
Front Immunol. 2023 Mar 14;14:1120996. doi: 10.3389/fimmu.2023.1120996. eCollection 2023.
, a cosmopolitan noninvasive protozoan parasite of zoonotic concern and public health importance, infects the upper portions of the small intestine and causes one of the most common gastrointestinal diseases globally termed giardiasis, especially in situations lacking safe drinking water and adequate sanitation services. The pathogenesis of giardiasis is complex and involves multiple factors from the interaction of and intestinal epithelial cells (IECs). Autophagy is an evolutionarily conserved catabolic pathway that involves multiple pathological conditions including infection. Thus far, it remains uncertain if autophagy occurs in -infected IECs and if autophagic process is associated with the pathogenic factors of giardiasis, such as tight junction (TJ) barrier defects and nitric oxide (NO) release of IECs. Here - exposed IECs showed upregulation of a series of autophagy-related molecules, such as LC3, Beclin1, Atg7, Atg16L1, and ULK1, and downregulation of p62 protein. IEC autophagy induced by was further assessed by using autophagy flux inhibitor, chloroquine (CQ), with the ratio of LC3-II/LC3-I significantly increased and downregulated p62 significantly reversed. Inhibition of autophagy by 3-methyladenine (3-MA) rather than CQ could markedly reverse -induced downregulation of TJ proteins (claudin-1, claudin-4, occludin, and ZO-1; also known as epithelial cell markers) and NO release, implying the involvement of early-stage autophagy in TJ/NO regulation. We subsequently confirmed the role of ROS-mediated AMPK/mTOR signaling in modulating -induced autophagy, TJ protein expression, and NO release. In turn, impairment of early-stage autophagy by 3-MA and late-stage autophagy by CQ both exhibited an exacerbated effect on ROS accumulation in IECs. Collectively, we present the first attempt to link the occurrence of IEC autophagy with infection , and provides novel insights into the contribution of ROS-AMPK/mTOR-dependent autophagy to infection-related downregulation of TJ protein and NO levels.
蓝氏贾第鞭毛虫是一种具有动物源性的非侵袭性原生动物寄生虫，具有动物源性和公共卫生重要性，感染小肠上部，导致全球最常见的胃肠道疾病之一，即贾第虫病，特别是在缺乏安全饮用水和充分卫生服务的情况下。贾第虫病的发病机制很复杂，涉及到和肠上皮细胞（IECs）相互作用的多个因素。自噬是一种进化上保守的分解代谢途径，涉及多种病理情况，包括感染。到目前为止，还不确定自噬是否发生在感染的 IECs 中，以及自噬过程是否与贾第虫病的致病因素有关，如紧密连接（TJ）屏障缺陷和 IECs 释放一氧化氮（NO）。在这里，暴露于的 IECs 显示出一系列自噬相关分子的上调，如 LC3、Beclin1、Atg7、Atg16L1 和 ULK1，以及 p62 蛋白的下调。用自噬流抑制剂氯喹（CQ）进一步评估由引起的 IEC 自噬，LC3-II/LC3-I 的比值显著增加，p62 显著下调。用 3-甲基腺嘌呤（3-MA）而不是 CQ 抑制自噬可以显著逆转诱导的 TJ 蛋白（claudin-1、claudin-4、occludin 和 ZO-1；也称为上皮细胞标志物）和 NO 释放的下调，表明早期自噬参与 TJ/NO 调节。随后，我们证实了 ROS 介导的 AMPK/mTOR 信号在调节诱导的自噬、TJ 蛋白表达和 NO 释放中的作用。反过来，3-MA 对早期自噬的损害和 CQ 对晚期自噬的损害都表现出对 IEC 中 ROS 积累的加剧作用。总的来说，我们首次尝试将 IEC 自噬的发生与感染联系起来，并为 ROS-AMPK/mTOR 依赖性自噬对感染相关的 TJ 蛋白和 NO 水平下调的贡献提供了新的见解。
