Hydrogen peroxide enhances phagocytosis of Pseudomonas aeruginosa in hyperoxia

Abstract

Mechanical ventilation with hyperoxia is a necessary treatment for patients with respiratory distress. However, patients on mechanical ventilation have increased susceptibility to infection. Studies including ours have shown that reactive oxygen species (ROS), generated by exposure to prolonged hyperoxia, can cause a decrease in the phagocytic activity of alveolar macrophages. Hydrogen peroxide (H₂O₂) is a form of ROS generated under hyperoxic conditions. In this study, we examined whether treatment with H₂O₂ directly affects macrophage phagocytic ability in RAW 264.7 cells that were exposed to either 21% O₂ (room air) or 95% O₂ (hyperoxia). Moderate concentrations (ranging from 10 to 250 µM) of H₂O₂ significantly enhanced macrophage phagocytic activity and restored hyperoxia-suppressed phagocytosis through attenuation of hyperoxia-induced disorganization of actin cytoskeleton and actin oxidation. These results indicate that H₂O₂ at low–moderate concentrations can be beneficial to host immune responses by improving macrophage phagocytic activity.

Keywords::

• hydrogen peroxide
• hyperoxia
• phagocytosis
• macrophages

Acknowledgements

We thank Dr. Charles R. Ashby Jr, Maitreyi Muralidhar, and Ashwini Gore for insightful discussion and invaluable suggestions on this project/manuscript. This work was supported by grants from the American Lung Association of New York State (LLM), National Heart and Blood Institute (HL093708, LLM), St. John’s University College of Pharmacy, and Ministry of Education and Training, Vietnamese Government. Dr. Maria Entezari (Tahereh Tahera) is currently at LaGuardia Community College, City University of New York.

Declaration of interest

The authors report no declarations of interest. The authors are alone responsible for the content and writing of the paper.