Oxidative and nitrative stress-related changes in human lens epithelial cells following exposure to X-rays

Abstract

Purpose: There is limited understanding of the mechanistic effects of ionizing radiation (IR) exposure in cataract formation. In this study, we explored the effects of IR on reactive oxygen/nitrogen species (ROS and RNS) generation in human lens epithelial (HLE) cells as an early key event to long-term damage.

Materials and methods: HLE cell-line was exposed to X-rays at varied doses (0–5 Gy) and dose-rates. Cell lysates and supernatants were collected 20 h post-exposure and analysed for viability, cell cycling and metabolites of ROS (p, m-, o-, tyrosines, 3-chlorotyrosine (cl-tyrosine), 8-hydroxy deoxyguanosine, (8-OH-dG) and RNS (3-nitrotyrosine).

Results and conclusions: HLE cell-line exhibited a bi-phasic response in terms of cell viability, ROS and RNS profiles. At doses <0.5 Gy, ROS and RNS levels were lower than control and at higher doses (>0.5 Gy) a steady increase was observed in each metabolite. This response was observed irrespective of dose-rate. Among the associations tested, cl, p, m-tyrosine and 3-nitrotyrosine revealed changes (p < .05) at 5 Gy compared exclusively to 0.05 and 0.01 Gy. In addition, dose-rate related differences were observed. Overall, the data suggests that ROS and RNS are key events in radiation induced damage and this response is dependent on the dose and dose-rate of IR exposure.

Keywords:

• X-ray radiation
• oxidative stress
• human eye lens epithelial cells
• reactive oxygen species
• reactive nitrogen species
• cataract

Acknowledgements

The authors are grateful to Ruth Wilkins and Sami Qutob for critical review of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Health Canada A-based funds [#8R1055].

Notes on contributors

Simran Bahia

Simran Bahia is a student at University of Ottawa conducting her 4th year honors in Biopharmaceuticals.

Erica Blais

Erica Blais is a laboratory technician at Health Canada.

Sangeeta Murugkar

Sangeeta Murugkar is an associate professor at the Department of Physics at Carleton University.

Vinita Chauhan

Vinita Chauhan is a research scientist at the Radiobiology Division of Health Canada.

Premkumari Kumarathasan

Premkumari Kumarathason is a research scientist at the Toxicology Division of Health Canada.