Microcystin-LR induced DNA damage in human peripheral blood lymphocytes

Area of Science:

• Environmental toxicology
• Molecular toxicology
• Genetics

Background:

• Human exposure to microcystins, cyanobacterial toxins, is increasing due to climate change and eutrophication.
• Microcystins are linked to liver toxicity, but effects on other tissues and genotoxicity mechanisms are unclear.
• Microcystin-LR (MCLR) is a prevalent and potent microcystin variant.

Purpose of the Study:

• To investigate the genotoxic potential of MCLR in human peripheral blood lymphocytes (HPBLs).
• To elucidate the mechanisms underlying MCLR-induced DNA damage, focusing on oxidative stress.
• To assess the impact of MCLR on DNA damage and oxidative stress-responsive gene expression.

Main Methods:

• Comet assay to measure DNA strand breaks in HPBLs exposed to varying MCLR concentrations.
• Formamidopyrimidine-DNA glycosylase (Fpg) digestion to detect oxidative DNA damage.
• Cytokinesis-block micronucleus assay to assess chromosomal damage.
• Quantitative PCR to analyze the expression of selected DNA damage and oxidative stress genes.

Main Results:

• MCLR induced a dose- and time-dependent increase in DNA damage in HPBLs via the comet assay.
• Fpg digestion confirmed MCLR induces oxidative DNA damage.
• No significant increase in micronuclei, nucleoplasmic bridges, or nuclear buds was observed.
• Upregulation of DNA damage-responsive and oxidative stress genes occurred after 24-hour MCLR exposure.

Conclusions:

• MCLR acts as an indirect genotoxic agent by inducing oxidative stress in human lymphocytes.
• Lymphocytes are a target tissue for MCLR toxicity.
• The findings highlight the potential health risks associated with microcystin exposure in contaminated water sources.