How defined microbes influence the skin immune system remains poorly understood. Here we demonstrate that Corynebacteria, dominant members of the skin microbiota, promote a dramatic increase in the number and activation of a defined subset of γδ T cells. This effect is long-lasting, occurs independently of other microbes, and is, in part, mediated by interleukin (IL)-23. Under steady-state conditions, the impact of Corynebacterium is discrete and noninflammatory. However, when applied to the skin of a host fed a high-fat diet, Corynebacterium accolens alone promotes inflammation in an IL-23–dependent manner. Such effect is highly conserved among species of Corynebacterium and dependent on the expression of a dominant component of the cell envelope, mycolic acid. Our data uncover a mode of communication between the immune system and a dominant genus of the skin microbiota and reveal that the functional impact of canonical skin microbial determinants is contextually controlled by the inflammatory and metabolic state of the host.

定义的微生物如何影响皮肤免疫系统仍知之甚少。在这里，我们证明棒状杆菌（皮肤微生物群的主要成员）促进了γδT细胞的定义子集的数量和激活的急剧增加。这种作用是持久的，独立于其他微生物而发生，并且部分是由白介素（IL）-23介导的。在稳态条件下，棒状杆菌的影响是离散的且非炎性的。但是，当将其应用于高脂饮食宿主的皮肤上时，单独的棒杆菌即会以IL-23依赖性的方式促进炎症。在棒状杆菌种中，这种效果是高度保守的。并取决于细胞包膜的主要成分霉菌酸的表达。我们的数据揭示了免疫系统与皮肤微生物群的主要属之间的交流方式，并揭示了规范的皮肤微生物决定因素的功能影响在上下文中受宿主的炎症和代谢状态控制。