Effect of CAT gene polymorphism on sensitivity of human lymphocytes to genotoxic effect of organochlorine pesticide in vitro

Introduction. Over recent decades, toxicogenetic studies have focused on the issues of genome instability under the action of genotoxicants, taking into account biomarkers of sensitivity. The question about the genotoxic potential of chlorpyrifos remains open, since both positive and negative effects have been revealed in various tests.

The aim of the study is the investigation of sensitivity of donor peripheral blood lymphocytes to chlorpyrifos in vitro and evaluation of the contribution of polymorphism of antioxidant defense system genes (CAT (rs1001179), SOD2 (rs4880)) to the response of human cells to the action of genotoxicant.

Materials and methods. The DNA damaging effect of chlorpyrifos was assessed on lymphocytes from fifty two donors using DNA-comet assay with metabolic activation (+S9) and without it (–S9). The study of cytotoxic effects of chlorpyrifos on human lymphocytes was carried out using an automatic fluorescent cell analyzer ADAMII LS.

Results. Chlorpyrifos had a pronounced cytotoxic effect on lymphocytes in most donors in the absence of metabolic activation system. With increasing concentration of the pesticide in the medium and time of cultivation, the viability of lymphocytes decreased, and the proportion of cells in late apoptosis and necrosis increased. Positive genotoxic effects were found on the cells of 33 donors (-S9). In the presence of the S9, mild but statistically significant effects were detected only on cells from 2 donors. % DNA values in the comet tail after exposure to the pesticide varied for cells from different donors. In the absence of metabolic activation, a statistically significant increase in the level of DNA damage was found in cells of individuals with genotype AA (homozygote for the minor allele) for the CAT G262A catalase gene (rs1001179), compared with homozygote for the dominant GG allele.

Limitations. The genotoxicity of chlorpyryfos was studied in vitro.

Conclusion. The results of the study shown cytotoxic and genotoxic effects of chlorpyrifos. The sensitivity of lymphocytes from different donors to the pesticide was found to be significantly different. The association of the level of DNA damage under exposure of chlorpyrifos in vitro with the G262A polymorphism of the catalase gene was found. The research also confirms the possibility of using a model test-system with peripheral blood lymphocytes to assess the potential genetic risk for humans and to study the contribution of gene polymorphism to individual sensitivity to the action of genotoxicants.

Compliance with ethical standards. The study was approved by the Ethics Committee of the Federal Scientific Center of Hygiene named after F.F. Erisman of the Federal Service for Supervision in Protection of the Rights of Consumer and Man Wellbeing, (Protocol No. 1, September 29, 2020).

Contribution:
Rakitskii V.N. — academic supervision;
Ilyushina N.A. — concept and design of the study, processing of material, analysis of the results; writing the text;
Egorova O.V. — concept and design of the study, collecting and processing of material, analysis of the results; writing the text;
Averianova N.S., Kotnova A.P., Gorenskaya O.V. — the collection of material;
Ignatyev S.D. — processing of material.
All authors are responsible for the integrity of all parts of the manuscript and approval of the manuscript final version.

Conflict of interests. The authors declare no conflict of interest.

Acknowledgements. The authors thank to Bioline LLC and personally to Eduard Mingazov for the opportunity to conduct the study on the assessment of cytotoxic effects using the ADAMII LS, Nano Entek automated fluorescent cell analyzer obtained under a gratuitous lease agreement.

Received: June 21, 2024 / Revised: August 14, 2024 / Accepted:  September 23, 2024 / Published: October 16, 2024