Role of NADPH oxidase in radiation-induced pro-oxidative and pro-inflammatory pathways in mouse brain

Abstract

Purpose: The present study was designed to investigate our hypothesis that NADPH oxidase plays a role in radiation-induced pro-oxidative and pro-inflammatory environments in the brain.

Materials and methods: C57BL/6 mice received either fractionated whole brain irradiation or sham-irradiation. The mRNA expression levels of pro-inflammatory mediators, such as TNF-α and MCP-1, were determined by quantitative real-time RT-PCR. The protein expression levels of TNF-α, MCP-1, NOX-2 and Iba1 were detected by immunofluorescence staining. The levels of ROS were visualized by in situ DHE fluorescence staining.

Results: A significant up-regulation of mRNA and protein expression levels of TNF-α and MCP-1 was observed in irradiated mouse brains. Additionally, immunofluorescence staining of Iba1 showed a marked increase of microglial activation in mouse brain after irradiation. Moreover, in situ DHE fluorescence staining revealed that fractionated whole brain irradiation significantly increased production of ROS. Furthermore, a significant increase in immunoreactivity of NOX-2 was detected in mouse brain after irradiation. On the contrary, an enhanced ROS generation in mouse brain after irradiation was markedly attenuated in the presence of NOX inhibitors or NOX-2 neutralizing antibody.

Conclusions: These results suggest that NOX-2 may play a role in fractionated whole brain irradiation-induced pro-oxidative and pro-inflammatory pathways in mouse brain.

Keywords:

• Fractionated whole brain irradiation
• ROS
• NOX-2
• inflammation

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Hyung Joon Cho received his Ph.D. degree from Virginia Tech in 2015. He is a postdoctoral researcher at University of Miami Miller School of Medicine. His research interests include studying molecular and cellular mechanisms of neuroinflammation and oxidative stress in vitro/in vivo as well as cell?cell communication in blood?brain barrier.

Won Hee Lee received her Ph.D. degree from Virginia Tech in 2010. She is an instructor at Stanford University School of Medicine. Her research interests include studying effects of radiation on in vitro/in vivo models as well as stem cell and applying molecular imaging techniques in developing genetic therapy.

Olivia Min Ha Hwang received her B.S. degree from Virginia Tech in 2015.

William E. Sonntag is a Professor at Department of Geriatric Medicine, University of Oklahoma Health Sciences Center. His specific research interest is the interaction between the endocrine, vascular and the central nervous system that leads to mild cognitive impairment and specifically vascular cognitive impairment.

Yong Woo Lee is an Associate Professor at Department of Biomedical Engineering and Mechanics, Virginia Tech. His research focuses on the pro-oxidative and pro-inflammatory mechanisms of human chronic diseases including atherosclerosis and brain injury. In addition, he is interested in the biomedical applications of nanotechnology.

Additional information

Funding

The work was supported by the National Institute of Neurological Disorders and Stroke under NIH [grant number NS056218].