Commensal-dendritic-cell Interaction Specifies a Unique Protective Skin Immune Signature

Naik S, Bouladoux N, Linehan JL, Han SJ, Harrison OJ, Wilhelm C, Conlan S, Himmelfarb S, Byrd AL, Deming C, Quinones M, Brenchley JM, Kong HH, Tussiwand R, Murphy KM, Merad M, Segre JA, Belkaid Y.

Nature 2015 Jan5. Doi: 10.1038/nature14052

Belkaid Photo Collab.

Picture on left, from left to right: Michael Askenase, Jonathan Linehan, Vanessa Ridaura, Christoph Wilhelm, Allyson Byrd, Seong-Ji Han, Yasmine Belkaid, Denise Morais de Fonseca, Samira Tamoutounour, Timothy Hand, Sarah Himmelfarb, Nicolas Bouladoux, Oliver Harrison and Kimberly Beacht. Picture on the right: Shruti Naik

As the largest organ of the body, the skin represents the major site of interaction with microbes in the environment. This organ is also colonized by trillions of commensal microorganisms that play an important role in tissue homeostasis and local immunity. Skin microbial communities are highly diverse and can change over time, or in response to environmental challenges. In this context, how individual commensal microorganisms modulate skin immunity and the consequences of these responses for tissue physiology remains unknown. In the current study, we demonstrated that the skin immune system develops distinct responses to various defined commensals. In particular, we found that colonizing mice with Staphylococcus epidermidis increases the number of IL-17A+-producing CD8+ T cells in the skin. We next demonstrated that those cells are specific to S. epidermidis, enhance innate barrier immunity and provide heterologous protection against the cutaneous pathogen Candida albicans. Those commensal-specific T-cell responses result from the coordinated action of distinct subsets of skin resident dendritic cells and are not associated with inflammation. Altogether, these findings reveal that the immune cells found in the skin are able to rapidly sense and respond to alterations in microbial communities and have profound implications for our understanding of tissue-specific immunity and pathologies. PubMed:25539086