Mast Cells in Host Defense Against Cutaneous Staphylococcus aureus Infection.

Staphylococcus aureus is an opportunistic pathogen implicated in skin and soft-tissue infections and chronic inflammatory skin diseases, such as atopic dermatitis. These infections can range from mild to potentially life-threatening systemic illnesses progressing to bacteremia, endocarditis, and sepsis. Mast cells, traditionally recognized for their role in allergies, are highly abundant within the skin and are gaining recognition for their contribution to bacterial defense. Here, we discuss the role of mast cells in three models of S. aureus skin infection according to skin depth: epicutaneous sensitization, intradermal injections, and subcutaneous injections. During S. aureus skin infection, mast cells become activated and accumulate in infected skin, recognize bacterial toxins, and modulate the activity of other immune cells, including neutrophils and dendritic cells. We discuss areas of research that should be the target of future studies, such as neuroimmunology, infected excisional wounds, and risk of systemic illness. Our review aims to bring attention to the host-pathogen interaction between mast cells and S. aureus in the skin, both to encourage deeper investigation and inform the development of immunomodulatory-based therapeutics.