Genes of the major histocompatibility complex (MHC) have long been linked to odor signaling and recently researchers’ attention has focused on MHC structuring of microbial communities and how this may in turn impact odor. However, understanding of the mechanisms through which the MHC could affect the microbiota to produce a chemical signal that is both reliable and strong enough to ensure unambiguous transmission of behaviorally important information remains poor. This is largely because empirical studies are rare, predictions are unclear, and the underlying immunological mechanisms governing MHC–microbiota interactions are often neglected. Here, we review the immunological processes involving MHC class II (MHC-II) that could affect the commensal community. Focusing on immunological and medical research, we provide background knowledge for nonimmunologists by describing key players within the vertebrate immune system relating to MHC-II molecules (which present extracellular-derived peptides, and thus interact with extracellular commensal microbes). We then systematically review the literature investigating MHC–odor–microbiota interactions in animals and identify areas for future research. These insights will help to design studies that are able to explore the role of MHC-II and the microbiota in the behavior of wild populations in their natural environment and consequently propel this research area forward.

中文翻译：

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MHC 如何通过微生物群落调节社会气味？深入研究机制

主要组织相容性复合体 (MHC) 的基因长期以来一直与气味信号有关，最近研究人员的注意力集中在微生物群落的 MHC 结构以及这如何反过来影响气味。然而，对 MHC 影响微生物群以产生既可靠又足够强以确保行为重要信息的明确传输的化学信号的机制的理解仍然很差。这主要是因为经验研究很少，预测不清楚，而且控制 MHC-微生物群相互作用的潜在免疫机制经常被忽视。在这里，我们回顾了可能影响共生群落的涉及 MHC II 类 (MHC-II) 的免疫过程。专注于免疫学和医学研究，我们通过描述脊椎动物免疫系统中与 MHC-II 分子（呈现细胞外衍生肽，因此与细胞外共生微生物相互作用）相关的关键参与者，为非免疫学家提供背景知识。然后，我们系统地回顾了研究动物中 MHC-气味-微生物群相互作用的文献，并确定了未来研究的领域。这些见解将有助于设计能够探索 MHC-II 和微生物群在野生种群在自然环境中的行为中的作用的研究，从而推动该研究领域的发展。然后，我们系统地回顾了研究动物中 MHC-气味-微生物群相互作用的文献，并确定了未来研究的领域。这些见解将有助于设计能够探索 MHC-II 和微生物群在野生种群在自然环境中的行为中的作用的研究，从而推动该研究领域的发展。然后，我们系统地回顾了研究动物中 MHC-气味-微生物群相互作用的文献，并确定了未来研究的领域。这些见解将有助于设计能够探索 MHC-II 和微生物群在野生种群在自然环境中的行为中的作用的研究，从而推动该研究领域的发展。