Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2016 Nov;100(5):1005-1010.
doi: 10.1189/jlb.4VMAB0316-100RR. Epub 2016 Jun 22.

Staphylococcus aureus SaeR/S-regulated factors reduce human neutrophil reactive oxygen species production

Fermin E Guerra  1 , Conrad B Addison  2 , Nienke W M de Jong  3 , Joseph Azzolino  1 , Kyler B Pallister  1 , Jos A G van Strijp  3 , Jovanka M Voyich  4
Affiliations

Staphylococcus aureus SaeR/S-regulated factors reduce human neutrophil reactive oxygen species production

Fermin E Guerra et al. J Leukoc Biol. 2016 Nov.

Abstract

Neutrophils are the first line of defense after a pathogen has breached the epithelial barriers, and unimpaired neutrophil functions are essential to clear infections. Staphylococcus aureus is a prevalent human pathogen that is able to withstand neutrophil killing, yet the mechanisms used by S. aureus to inhibit neutrophil clearance remain incompletely defined. The production of reactive oxygen species (ROS) is a vital neutrophil antimicrobial mechanism. Herein, we test the hypothesis that S. aureus uses the SaeR/S two-component gene regulatory system to produce virulence factors that reduce neutrophil ROS production. With the use of ROS probes, the temporal and overall production of neutrophil ROS was assessed during exposure to the clinically relevant S. aureus USA300 (strain LAC) and its isogenic mutant LACΔsaeR/S Our results demonstrated that SaeR/S-regulated factors do not inhibit neutrophil superoxide (O2-) production. However, subsequent neutrophil ROS production was significantly reduced during exposure to LAC compared with LACΔsaeR/S In addition, neutrophil H2O2 production was reduced significantly by SaeR/S-regulated factors by a mechanism independent of catalase. Consequently, the reduction in neutrophil H2O2 resulted in decreased production of the highly antimicrobial agent hypochlorous acid/hypochlorite anion (HOCl/-OCl). These findings suggest a new evasion strategy used by S. aureus to diminish a vital neutrophil antimicrobial mechanism.

Keywords: bacteria; host-pathogen interactions; innate immunity; two-component systems.

PubMed Disclaimer

Figures

Figure 1.
Figure 1.. SaeR/S-regulated factors decrease intracellular ROS.
Human PMNs were preloaded with luminol, as described in Materials and Methods, and exposed to LAC, LACΔsaeR/S, or RPMI, and chemiluminescence was measured. (A) Time-dependent neutrophil intracellular ROS production following exposure to S. aureus LAC or LACΔsaeR/S. (B) Total relative neutrophil ROS production determined by calculating the area under the curve (AUC) from A. (C) Time-dependent neutrophil intracellular ROS production following exposure to S. aureus LAC or LACΔsaeR/S in the presence of exogenous SOD. (D) Total relative neutrophil ROS production determined by calculating the area under the curve from C. (E) Time-dependent neutrophil intracellular ROS production following exposure to S. aureus LAC or LACΔsaeR/S in the presence of exogenous catalase. (F) Total relative neutrophil ROS production determined by calculating the area under the curve from E. Data represent 5 separate experiments, using 5 different neutrophil donors; *P ≤ 0.05, **P ≤ 0.01, as determined by two-way ANOVA (A, C, and E) and one-way ANOVA (B, D, and F). RLUs, Relative luminescence units.
Figure 2.
Figure 2.. Human neutrophil extracellular O2− production following exposure to WT S. aureus LAC and LACΔsaeR/S using isoluminol.
(A) Time-dependent neutrophil extracellular O2− production following exposure to S. aureus LAC or LACΔsaeR/S. (B) Total relative neutrophil O2− production determined by calculating the area under the curve from A. Data represent 4 separate experiments, using 4 different neutrophil donors; **P ≤ 0.01, as determined by two-way ANOVA (A) and one-way ANOVA (B).
Figure 3.
Figure 3.. Human neutrophil extracellular H2O2 production is significantly reduced by SaeR/S-regulated S. aureus factors.
(A) Time-dependent neutrophil extracellular H2O2 production was measured using Amplex Red, following exposure S. aureus LAC or LACΔsaeR/S or RPMI as a control. (B) Neutrophil-derived extracellular H2O2 production calculated from an H2O2 standard curve. (C) Secreted catalase following S. aureus exposure to human neutrophils. Bacteria exposed (+) or not exposed (−) to neutrophils. Data represent 4 separate experiments (A and C) and 5 separate experiments (B), with *P ≤ 0.05, as determined by two-way ANOVA (A) and paired t test (B).
Figure 4.
Figure 4.. Human neutrophil intracellular hypochlorite production is reduced significantly by SaeR/S-regulated S. aureus factors.
HOCl production was measured in human neutrophils using R19-S, following exposure to WT S. aureus LAC or LACΔsaeR/S. (A) Representative plot of time-dependent neutrophil intracellular HOCl production following exposure to S. aureus LAC or LACΔsaeR/S or LAC HK or RPMI as a control. (B) Relative neutrophil-derived HOCl production at the end of the 90 min assay from A. (C) Relative neutrophil-derived intracellular HOCl measured by flow cytometry. Data represent 9 separate experiments (B) and 6 separate experiments (C); **P ≤ 0.01, ***P ≤ 0.001, as determined by paired t test (B and C). RFUs, Relative fluorescence units.
Figure 5.
Figure 5.. S. aureus LAC and LACΔsaeR/S are equally susceptible to killing by HOCl.
Bacteria (1 × 107) were exposed to different concentrations of HOCl for 30 min at 37°C. Subsequently, bacteria were serially diluted and plated on trypticase soy agar plates, and CFUs were enumerated following overnight incubation at 37°C. Data represent 5 separate experiments.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Amulic B., Cazalet C., Hayes G. L., Metzler K. D., Zychlinsky A. (2012) Neutrophil function: from mechanisms to disease. Annu. Rev. Immunol. 30, 459–489. - PubMed
    1. Nordenfelt P., Tapper H. (2011) Phagosome dynamics during phagocytosis by neutrophils. J. Leukoc. Biol. 90, 271–284. - PubMed
    1. Hurst J. K. (2012) What really happens in the neutrophil phagosome? Free Radic. Biol. Med. 53, 508–520. - PMC - PubMed
    1. DeLeo F. R., Quinn M. T. (1996) Assembly of the phagocyte NADPH oxidase: molecular interaction of oxidase proteins. J. Leukoc. Biol. 60, 677–691. - PubMed
    1. DeLeo F. R., Allen L. A., Apicella M., Nauseef W. M. (1999) NADPH oxidase activation and assembly during phagocytosis. J. Immunol. 163, 6732–6740. - PubMed

Publication types

MeSH terms