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Skin immune responses against pathogens

Establishing immunity against infection requires the activation of memory T cells. Understanding how these cells are generated in the dermis is paramount for designing appropriate interventions.
Skin immune responses against pathogens
Staphylococcus aureus (SA) is responsible for the vast majority of bacterial skin infections in humans and poses a major public health threat. Unlike typical encapsulated bacteria, which induce efficient protective humoral immune responses, existing evidence suggests that antibody responses are insufficient to protect against SA. Rather, IL-17-producing T cells provide cell-mediated immunity against SA.

It seems that resident microbiota plays a pivotal role in protective responses against skin pathogens. In healthy individuals, bacteria belonging to the Staphylococcus species are commensal to body surfaces like the skin. Therefore, the EU-funded METAPATH (Integrated study of skin resident memory T cells and dermal mononuclear phagocytes in the fight against pathogens) project investigated the importance of skin colonisation by SA in mounting an immune response against SA.

Researchers employed a mouse model of SA skin colonisation and showed a faster pathogen clearance upon secondary infection with SA. Subsequent analysis of both the innate and adaptive compartments of the immune response indicated a specific immune signature associated with protective immunity against SA. Importantly, a single topical application of SA was sufficient to induce long term protective memory against SA in these mice. Furthermore, they showed that neutrophils were not responsible for the innate and adaptive T cell responses against SA.

Next, considering the role of dermal dendritic cells in recognising, processing and conveying foreign material from the periphery to the draining lymph nodes, scientists investigated their potential implication in the anti-SA response. In this context, they used specialised mouse models with impairment of specific dendritic cell subsets. Their results delineated the role of this specific migratory DC subset in the induction of adaptive immune response against SA. A key role of γδ T cells was also demonstrated for short term memory.

Collectively, the findings of the METAPATH study enhance the knowledge on the immune mechanisms associated with skin colonisation and on the immune responses that protect against SA infection. This information has important consequences for the design of vaccine strategies against SA.

Related information

Subjects

Life Sciences

Keywords

Skin, Staphylococcus aureus, METAPATH, dendritic cell, γδ T cell
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