Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, VIC, Australia.
Department of Biochemistry and Pharmacology, Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Melbourne, VIC, Australia.
Front Immunol. 2022 Jul 8;13:897462. doi: 10.3389/fimmu.2022.897462. eCollection 2022.
The respiratory tract is a gateway for viruses and bacteria from the external environment to invade the human body. Critical to the protection against these invaders are dendritic cells (DCs) - a group of highly specialized myeloid cells that monitors the lung microenvironment and relays contextual and antigenic information to T cells. Following the recognition of danger signals and/or pathogen molecular associated patterns in the lungs, DCs undergo activation. This process arms DCs with the unique ability to induce the proliferation and differentiation of T cells responding to matching antigen in complex with MHC molecules. Depending on how DCs interact with T cells, the ensuing T cell response can be tolerogenic or immunogenic and as such, the susceptibility and severity of respiratory infections is influenced by the signals DCs receive, integrate, and then convey to T cells. It is becoming increasingly clear that these facets of DC biology are heavily influenced by the cellular components and metabolites produced by the lung and gut microbiota. In this review, we discuss the roles of different DC subsets in respiratory infections and outline how microbial metabolites impact the development, propensity for activation and subsequent activation of DCs. In particular, we highlight these concepts in the context of respiratory immunity.
呼吸道是病毒和细菌从外部环境侵入人体的门户。树突状细胞（DCs）是保护人体免受这些入侵的关键——DCs 是一组高度特化的髓系细胞，可监测肺部微环境，并将上下文和抗原信息传递给 T 细胞。在识别肺部的危险信号和/或病原体分子相关模式后，DCs 会被激活。这个过程赋予了 DCs 独特的能力，可诱导与 MHC 分子结合的匹配抗原的 T 细胞增殖和分化。根据 DCs 与 T 细胞的相互作用方式，随后的 T 细胞反应可能具有耐受性或免疫原性，因此，DCs 接收到的信号、整合的信号以及随后传递给 T 细胞的信号会影响呼吸道感染的易感性和严重程度。越来越明显的是，DC 生物学的这些方面受到肺部和肠道微生物群产生的细胞成分和代谢物的强烈影响。在这篇综述中，我们讨论了不同 DC 亚群在呼吸道感染中的作用，并概述了微生物代谢物如何影响 DCs 的发育、激活倾向以及随后的激活。特别是，我们在呼吸道免疫的背景下强调了这些概念。
