Human Immunity Against Staphylococcus Aureus Skin Infection

The incidence of community-associated (CA) staphylococcal infections, especially those caused by methicillin-resistant Staphylococcus aureus (MRSA), has increased dramatically in recent years. Skin and soft tissues are the primary site for most of these infections, and skin or mucosal colonization increases the risk of disseminated disease. Many patients without apparent underlying immune dysfunction suffer from recurrent and persistent skin infections with MRSA. Additionally, patients with conditions such as atopic dermatitis and Hyper IgE (or Job s) Syndrome (HIES) are disproportionately affected. Although underlying host molecular defects responsible for some of these predisposing conditions have been uncovered in recent years (e.g. STAT3 mutations in HIES), the skin immune response to S. aureus infections has not been elucidated in either healthy controls or susceptible populations. In this protocol, we will perform exploratory evaluations of anti-staphylococcal immune responses in healthy subjects, subjects with STAT3 mutations, and otherwise healthy subjects with a history of recurrent staphylococcal skin infections. An additional group of subjects with other underlying conditions of interest may be included.

The primary objective of this research is to perform in vivo and ex vivo challenges with killed bacteria through the use of the skin blister model and keratinocyte cultures to evaluate skin immune responses. Occasionally, a commensal fungi, such as Candida species may also be used. We will use three experimental approaches to complete this objective: 1) evaluation of in vivo responses in skin blisters to killed microbe exposure, 2) ex vivo evaluation of anti-microbial responses through derivation of keratinocyte cultures from skin blisters or biopsies, and 3) evaluation of function and immune-stimulatory ability of commensal organisms.

Specifically, a suction blister device will be used to induce a skin blister on the forearm. The tops of the blisters will be removed, and solutions of killed S. aureus, commensal coagulase-negative staphylococcal species, or other Gram-negative commensals as well as commensal fungi, such as Candida species will be applied to the blisters to stimulate inflammatory responses. The blister fluid will then be collected at various time points over 24 hours for laboratory analysis. Baseline skin and/or nasal swabs, skin biopsies, and blood draws will also be performed (The skin and nasal swabs may be performed at the screening or baseline visit.). Pediatric participants may be enrolled for baseline skin and/or nasal swabs. All research procedures will be performed at the National Institutes of Health Clinical Center. We anticipate that the research will provide critical new information on the human skin immune response to S. aureus that has direct relevance for the development of vaccines, diagnostics, and therapeutics.