Influenza infection suppresses NADPH oxidase-dependent phagocytic bacterial clearance and enhances susceptibility to secondary methicillin-resistant Staphylococcus aureus infection

Keer Sun, Dennis W. Metzger

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a leading contributor to mortality during recent influenza pandemics. The mechanism for this influenza-induced susceptibility to secondary S. aureus infection is poorly understood. In this study, we show that innate antibacterial immunity was significantly suppressed during the recovery stage of influenza infection, even though MRSA superinfection had no significant effect on viral burdens. Compared with mice infected with bacteria alone, postinfluenza MRSA-infected mice exhibited impaired bacterial clearance, which was not due to defective phagocyte recruitment, but rather coincided with reduced intracellular reactive oxygen species levels in alveolar macrophages and neutrophils. NADPH oxidase is responsible for reactive oxygen species production during phagocytic bacterial killing, a process also known as oxidative burst. We found that gp91phox-containing NADPH oxidase activity in macrophages and neutrophils was essential for optimal bacterial clearance during respiratory MRSA infections. In contrast to wild-type animals, gp91phox-/- mice exhibited similar defects in MRSA clearance before and after influenza infection. Using gp91phox+/- mosaic mice, we further demonstrate that influenza infection inhibits a cell-intrinsic contribution of NADPH oxidase to phagocyte bactericidal activity. Taken together, our results establish that influenza infection suppresses NADPH oxidase-dependent bacterial clearance and leads to susceptibility to secondary MRSA infection. The Journal of Immunology, 2014, 192: 3301-3307.

Original languageEnglish (US)
Pages (from-to)3301-3307
Number of pages7
JournalJournal of Immunology
Volume192
Issue number7
DOIs
StatePublished - Apr 1 2014

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NADPH Oxidase
Methicillin-Resistant Staphylococcus aureus
Human Influenza
Infection
Phagocytes
Reactive Oxygen Species
Neutrophils
Superinfection
Wild Animals
Respiratory Burst
Alveolar Macrophages
Pandemics
Allergy and Immunology
Viral Load
Innate Immunity
Staphylococcus aureus
Macrophages
Bacteria
Mortality

ASJC Scopus subject areas

  • Immunology

Cite this

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title = "Influenza infection suppresses NADPH oxidase-dependent phagocytic bacterial clearance and enhances susceptibility to secondary methicillin-resistant Staphylococcus aureus infection",
abstract = "Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a leading contributor to mortality during recent influenza pandemics. The mechanism for this influenza-induced susceptibility to secondary S. aureus infection is poorly understood. In this study, we show that innate antibacterial immunity was significantly suppressed during the recovery stage of influenza infection, even though MRSA superinfection had no significant effect on viral burdens. Compared with mice infected with bacteria alone, postinfluenza MRSA-infected mice exhibited impaired bacterial clearance, which was not due to defective phagocyte recruitment, but rather coincided with reduced intracellular reactive oxygen species levels in alveolar macrophages and neutrophils. NADPH oxidase is responsible for reactive oxygen species production during phagocytic bacterial killing, a process also known as oxidative burst. We found that gp91phox-containing NADPH oxidase activity in macrophages and neutrophils was essential for optimal bacterial clearance during respiratory MRSA infections. In contrast to wild-type animals, gp91phox-/- mice exhibited similar defects in MRSA clearance before and after influenza infection. Using gp91phox+/- mosaic mice, we further demonstrate that influenza infection inhibits a cell-intrinsic contribution of NADPH oxidase to phagocyte bactericidal activity. Taken together, our results establish that influenza infection suppresses NADPH oxidase-dependent bacterial clearance and leads to susceptibility to secondary MRSA infection. The Journal of Immunology, 2014, 192: 3301-3307.",
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AB - Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a leading contributor to mortality during recent influenza pandemics. The mechanism for this influenza-induced susceptibility to secondary S. aureus infection is poorly understood. In this study, we show that innate antibacterial immunity was significantly suppressed during the recovery stage of influenza infection, even though MRSA superinfection had no significant effect on viral burdens. Compared with mice infected with bacteria alone, postinfluenza MRSA-infected mice exhibited impaired bacterial clearance, which was not due to defective phagocyte recruitment, but rather coincided with reduced intracellular reactive oxygen species levels in alveolar macrophages and neutrophils. NADPH oxidase is responsible for reactive oxygen species production during phagocytic bacterial killing, a process also known as oxidative burst. We found that gp91phox-containing NADPH oxidase activity in macrophages and neutrophils was essential for optimal bacterial clearance during respiratory MRSA infections. In contrast to wild-type animals, gp91phox-/- mice exhibited similar defects in MRSA clearance before and after influenza infection. Using gp91phox+/- mosaic mice, we further demonstrate that influenza infection inhibits a cell-intrinsic contribution of NADPH oxidase to phagocyte bactericidal activity. Taken together, our results establish that influenza infection suppresses NADPH oxidase-dependent bacterial clearance and leads to susceptibility to secondary MRSA infection. The Journal of Immunology, 2014, 192: 3301-3307.

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