The Role of Interleukin-12 in Protection against Pulmonary Infection with Methicillin-Resistant Staphylococcus aureus.

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The Role of Interleukin-12 in Protection against Pulmonary Infection with Methicillin-Resistant Staphylococcus aureus.

Antimicrob Agents Chemother. 2015 Jul 27;

Authors: Nguyen QT, Furuya Y, Roberts S, Metzger DW

Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is a common pathogen associated with nosocomial pneumonia and is an increasing threat for severe community-acquired pneumonia. We have now investigated the role of interleukin-12 (IL-12) in protective immunity against lung infection with MRSA. The importance of IL-12 in protection from pulmonary MRSA infection was demonstrated by the finding that IL-12p35-deficient mice had a lower survival rate, higher bacterial burdens in both lung and spleen, and decreased expression of interferon-gamma (IFN-γ) in the lung compared to wild-type mice. These effects were completely reversed by replacement intranasal therapy with recombinant IL-12. Furthermore, exogenous IL-12 treatment of wild-type mice 24 hr before pulmonary challenge with a lethal dose of MRSA significantly improved bacterial clearance and resulted in protection from death. The IL-12-treated mice had increased numbers of lung natural killer (NK) cells and neutrophils, and higher levels of IFN-γ in the lung and serum compared to untreated mice. The major source of IL-12-driven IFN-γ expression in the lung was the NK cell and the direct target of pulmonary IFN-γ was the lung macrophage as shown using mice with a macrophage-specific defect in interferon gamma (IFN-γ) signaling (MIIG mice). Importantly, combination therapy with linezolid and IL-12 following intranasal MRSA infection significantly increased survival compared to mice receiving linezolid or IL-12 alone. These results indicate that IL-12-based immunotherapy may hold promise for treatment of MRSA pneumonia.

PMID: 26248370 [PubMed - as supplied by publisher]