Chlorpyrifos Induces Apoptosis in Macrophages by Activating Both Intrinsic and Extrinsic Apoptotic Pathways

Area of Science:

• Immunotoxicology
• Cellular Biology
• Environmental Health

Background:

• Chlorpyrifos is a widely used pesticide with known environmental and human health risks.
• While its neurotoxic and genotoxic effects are documented, its impact on the immune system is not fully understood.
• Investigating chlorpyrifos's specific toxicity mechanisms in immune cells is crucial.

Purpose of the Study:

• To elucidate the apoptotic pathways induced by chlorpyrifos in macrophages.
• To determine the roles of intrinsic and extrinsic apoptotic signaling in chlorpyrifos-induced cytotoxicity.
• To assess the concentration-dependent effects of chlorpyrifos on macrophage viability and apoptosis.

Main Methods:

• RAW 264.7 macrophages were exposed to varying concentrations of chlorpyrifos.
• Cytotoxicity was measured using lactate dehydrogenase assay.
• Apoptosis, caspase activation (caspase-3, -8, -9), mitochondrial function, death receptor expression, cytochrome c release, and Bcl2 family proteins were analyzed via flow cytometry and Western blotting.

Main Results:

• Chlorpyrifos induced concentration-dependent cytotoxicity and apoptosis in macrophages.
• Activation of caspase-3, caspase-8, and caspase-9 was observed.
• Mitochondrial dysfunction, cytochrome c release, altered Bcl2 family protein expression, and increased death receptor expression were confirmed.

Conclusions:

• Chlorpyrifos triggers apoptosis in macrophages via a caspase-3-dependent mechanism.
• Both intrinsic (involving caspase-8, mitochondrial pathways) and extrinsic (involving caspase-9, death receptors) apoptotic pathways are activated by chlorpyrifos.
• These findings reveal significant immunotoxicity of chlorpyrifos, contributing to its overall health risks.