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

• Published in: Environmental toxicology Vol. 40; no. 9; pp. 1150 - 1159
• Main Authors: Chiang, Chen‐Yu, Liu, Shin‐Wu, Chen, Chun‐Jung, Chen, Wen‐Ying
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.09.2025
• Subjects: Animals; Apoptosis; Apoptosis - drug effects; Bcl-2 protein; Caspase; Caspases - metabolism; Cell Survival - drug effects; Chlorpyrifos; Chlorpyrifos - toxicity; Cytochrome; Cytochrome c; Cytochromes; Cytochromes c - metabolism; Cytotoxicity; Damage; Death receptors; DNA damage; fas Receptor - metabolism; Flow cytometry; Genotoxicity; Immune system; Insecticides - toxicity; L-Lactate dehydrogenase; Lactate; Lactate dehydrogenase; Macrophages; Macrophages - drug effects; Macrophages - metabolism; Mice; Mitochondria; Mitochondria - drug effects; Mitochondria - metabolism; Necrosis; Neoplasms; Neurotoxicity; Oxidative stress; Pesticide toxicity; Pesticides; Proteinase; Proteins; RAW 264.7 Cells; Reagents; Receptor mechanisms; Receptors; Toxicity; Tumor necrosis factor; Tumor necrosis factor-TNF; Western blotting; extrinsic apoptotic pathway; apoptosis; intrinsic apoptotic pathway; macrophages; chlorpyrifos
• ISSN: 1520-4081; 1522-7278; 1522-7278
• DOI: 10.1002/tox.24515

Although chlorpyrifos poses considerable risks to the environment and human health, it is still used in many countries. This pesticide has various toxic effects on humans, including neurotoxicity, reproductive toxicity, genotoxicity, and organ damage caused by oxidative stress and DNA damage. However, its specific toxicity to the immune system remains unclear. In this study, we explored the intrinsic and extrinsic apoptotic pathways through which chlorpyrifos induces apoptosis in macrophages. RAW 264.7 macrophages were treated with chlorpyrifos at concentrations of 0, 2, 4, 10, and 20 ppm for 3 h. Cytotoxicity was assessed using a lactate dehydrogenase assay, whereas apoptosis was evaluated through flow cytometry. The levels of cysteinyl aspartate‐specific proteinase (caspase)‐3, caspase‐8, and caspase‐9 were measured. The disruption of mitochondrial function and the expression of the death receptors Fas receptor and tumor necrosis factor‐alpha receptor were assessed through JC‐1 stain reagent. The release of mitochondrial cytochrome c, expression of Bcl2 family proteins, and level of cleaved caspases were analyzed through Western blotting. Chlorpyrifos induced cytotoxicity and apoptosis in a concentration‐dependent manner. It activated caspase‐3, caspase‐8, and caspase‐9, as well as disrupted mitochondrial function and Bcl2 family protein balance. Furthermore, chlorpyrifos induced the release of cytochrome c from the mitochondria and upregulated the expression of Fas receptor and tumor necrosis factor‐alpha receptor. These findings suggest that chlorpyrifos induces cytotoxicity through caspase‐3‐dependent apoptosis via the intrinsic pathway (caspase‐8 activation, mitochondrial dysfunction, Bcl2 protein imbalance, and cytochrome c release) and the extrinsic pathway (caspase‐9 activation and death receptor expression).