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Journal of Innate Immunity: New research article from Dr. Eva Medina's Infection Immunology Research Group

Friday, 22. July 2011

Staphylococcus aureus Evades the Extracellular Antimicrobial Activity of Mast Cells by Promoting Its Own Uptake

Jens Abel a, Oliver Goldmann a, Christina Ziegler a, Claudia Höltje a, Mark S. Smeltzer c, Ambrose L. Cheung d, Daniela Bruhn a, Manfred Rohde b, Eva Medina a

(a Infection Immunology Research Group and b Department of Medical Microbiology, Helmholtz Centre for Infection Research, Braunschweig, Germany; c Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Ark. , and d Department of Microbiology, Dartmouth Medical School, Hanover, N.H. , USA.)

Key Words

Mast cells | Staphylococcus aureus | Antimicrobial activity | Intracellular persistence

Abstract

In this study, we investigated the interactions of Staphylococcus aureus with mast cells, which are multifunctional sentinels lining the surfaces of the body. We found that bone marrow-derived murine mast cells (BMMC) exerted a powerful phagocytosis-independent antimicrobial activity against S. aureus. Both the release of extracellular traps as well as discharge of antimicrobial compounds were the mechanisms used by the BMMC to kill extracellular S. aureus. This was accompanied by the secretion of mediators such as TNF-α involved in the recruitment of effector cells. Interestingly, S. aureus subverted the extracellular antimicrobial activity of the BMMC by internalizing within these cells. S. aureus was also capable to internalize within human mast cells (HMC-1) and within murine skin mast cells during in vivo infection. Bacteria internalization was, at least in part, mediated by the α5β1 integrins expressed on the surface of the mast cell. In the intracellular milieu, the bacterium survived and persisted by increasing the cell wall thickness and by gaining access into the mast cell cytosol. The expression of α-hemolysin was essential for staphylococci intracellular persistence. By hiding within the long-life mast cells, staphylococci not only avoid clearance but also establish an infection reservoir that could contribute to chronic carriage.

J Innate Immun (DOI: 10.1159/000327714)



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