The mammalian intestine is home to trillions of microbes, and their colonization contributes to host physiology through the production of indispensable metabolites and competition against pathogens. However, it is also important to balance this symbiotic relationship, as overgrowth and translocation of microbes could trigger a fatal infection. IgA is the major immunoglobulin class produced and secreted in the intestine and is considered to play a pivotal role in maintaining homeostasis. In this review, we summarize recent studies exploring the interactions between IgA and the gut microbiota, and explain how different types of IgA could coexist to regulate the gut microbiota. In particular, we discuss two important aspects of IgA in controlling the gut microbes: function and specificity. Differences in these two aspects appear attributable to how IgA is induced and are associated with the functions of IgA as well. Together, our review delineates a recent understanding of IgA–microbiome interactions and proposes a future direction to clarify its complexity.

中文翻译：

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IgA 和肠道微生物群的相互调节：肠道中的关键共生关系

哺乳动物的肠道是数以万亿计微生物的家园，它们的定植通过产生不可或缺的代谢物和与病原体的竞争来促进宿主生理。然而，平衡这种共生关系也很重要，因为微生物的过度生长和易位可能引发致命的感染。IgA 是在肠道中产生和分泌的主要免疫球蛋白类别，被认为在维持体内平衡中起关键作用。在这篇综述中，我们总结了近期探索 IgA 与肠道微生物群之间相互作用的研究，并解释了不同类型的 IgA 如何共存以调节肠道微生物群。特别是，我们讨论了 IgA 在控制肠道微生物方面的两个重要方面：功能和特异性。这两个方面的差异似乎可归因于 IgA 的诱导方式，并且也与 IgA 的功能相关。总之，我们的综述描述了最近对 IgA-微生物组相互作用的理解，并提出了未来的方向来阐明其复杂性。