INRAE, AgroParisTech, Micalis Institute, Université Paris-Saclay, Jouy-en-Josas, France.
INSERM, Institut Cochin, Université de Paris Cité, CNRS, Paris, France.
Gut Microbes. 2022 Jan-Dec;14(1):2110639. doi: 10.1080/19490976.2022.2110639.
The commensal bacteria that make up the gut microbiota impact the health of their host on multiple levels. In particular, the interactions taking place between the microbe-associated molecule patterns (MAMPs) and pattern recognition receptors (PRRs), expressed by intestinal epithelial cells (IECs), are crucial for maintaining intestinal homeostasis. While numerous studies showed that TLRs and NLRs are involved in the control of gut homeostasis by commensal bacteria, the role of additional innate immune receptors remains unclear. Here, we seek for novel MAMP-PRR interactions involved in the beneficial effect of the commensal bacterium on intestinal homeostasis. We show that strongly activates NF-κB in IECs by releasing one or more potent activating metabolites into the microenvironment. By using drugs, chemical and gene-editing tools, we found that the released metabolite(s) enter(s) epithelial cells and activate(s) NF-κB via an ALPK1, TIFA and TRAF6-dependent pathway. Furthermore, we show that the released molecule has the biological characteristics of the ALPK1 ligand ADP-heptose. Finally, we show that induces the expression of the and genes involved in the maintenance of the intestinal barrier function and that this process is dependent on TIFA. Altogether, our data strongly suggest that the commensal promotes intestinal homeostasis by activating the ALPK1/TIFA/TRAF6 axis, an innate immune pathway exclusively described so far in the context of Gram-negative bacterial infections.
定殖于肠道的共生菌(肠道微生物群)通过多个层面影响宿主健康。特别是,肠道上皮细胞(IECs)表达的微生物相关分子模式(MAMPs)与模式识别受体(PRRs)之间的相互作用对于维持肠道内稳态至关重要。虽然许多研究表明 TLRs 和 NLRs 参与了共生菌对肠道内稳态的控制,但其他先天免疫受体的作用仍不清楚。在这里,我们寻求参与共生菌对肠道内稳态有益作用的新型 MAMP-PRR 相互作用。我们发现 通过向微环境中释放一种或多种有效的激活代谢物,强烈激活 IECs 中的 NF-κB。通过使用药物、化学和基因编辑工具,我们发现释放的代谢物通过 ALPK1、TIFA 和 TRAF6 依赖性途径进入上皮细胞并激活 NF-κB。此外,我们表明释放的分子具有 ALPK1 配体 ADP-庚糖的生物学特征。最后,我们表明 诱导参与维持肠道屏障功能的 和 基因的表达,并且该过程依赖于 TIFA。总之,我们的数据强烈表明,共生菌通过激活 ALPK1/TIFA/TRAF6 轴促进肠道内稳态,这是迄今为止仅在革兰氏阴性菌感染的背景下描述的先天免疫途径。
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