The innate immune system in the central nervous system (CNS) is mainly represented by specialized tissue‐resident macrophages, called microglia. In the past years, various species‐, host‐ and tissue‐specific as well as environmental factors were recognized that essentially affect microglial properties and functions in the healthy and diseased brain. Host microbiota are mostly residing in the gut and contribute to microglial activation states, for example, via short‐chain fatty acids (SCFAs) or aryl hydrocarbon receptor (AhR) ligands. Thereby, the gut microorganisms are deemed to influence numerous CNS diseases mediated by microglia. In this review, we summarize recent findings of the interaction between the host microbiota and the CNS in health and disease, where we specifically highlight the resident gut microbiota as a crucial environmental factor for microglial function as what we coin “the microbiota‐microglia axis.”

中文翻译：

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中枢神经系统疾病中的微生物群-小胶质细胞轴

中枢神经系统（CNS）中的先天免疫系统主要由专门的组织驻留巨噬细胞（称​​为小胶质细胞）代表。在过去的几年中，人们认识到各种物种、宿主和组织特异性以及环境因素从本质上影响健康和患病大脑中的小胶质细胞特性和功能。宿主微生物群主要存在于肠道中，并通过短链脂肪酸（SCFA）或芳基烃受体（AhR）配体等方式促进小胶质细胞激活状态。因此，肠道微生物被认为影响小胶质细胞介导的多种中枢神经系统疾病。在这篇综述中，我们总结了宿主微生物群与中枢神经系统在健康和疾病中相互作用的最新发现，其中我们特别强调常驻肠道微生物群是小胶质细胞功能的关键环境因素，即我们所说的“微生物群-小胶质细胞轴”。 ”