Differential immunomodulatory effects of six pesticides of different chemical classes on human monocyte-derived macrophage functions

Exposure to pesticides through eyes, skin, ingestion and inhalation may affects human health by interfering with immune cells, such as macrophages. We evaluated, in vitro, the effect of six pesticides widely used in apple arboriculture on the functions of human monocyte-derived macrophages (hMDMs). hMDMs were cultured for 4 or 24 h with or without pesticides (0.01, 0.1, 1, 10 mu mol.L-1). We showed that chlorpyrifos, thiacloprid, thiophanate, boscalid, and captan had little toxic effect at the tested concentrations, while dithianon had lowcytotoxicity at 10 mu mol.L- 1. While boscalid showed no effect on hMDMs function, thiophanate (0.01 mu mol. L-1) stimulated with TPA and thiacloprid (1, 10 mu mol.L- 1) stimulated with zymosan activated ROS production. Chlorpyrifos, dithianon, and captan inhibited ROS production and TNF-alpha, IL-1I3 pro-inflammatory cytokines. We established that dithianon (0.01-1 mu mol.L- 1) and captan (0.1, 1 mu mol.L- 1) induced mRNA expression of NQO1 and HMOX1 antioxidant enzymes. Dithianon also induced the mRNA expression of catalase, superoxide dismutase-2 at 10 mu mol.L- 1. Together, these results show that exposure to chlorpyrifos, dithianon, and captan induce immunomodulatory effects that may influence the disease fighting properties of monocytes/macrophages while pesticides such as thiacloprid, thiophanate and boscalid have little influence.

Automated summary

This study examined the effects of six pesticides commonly used in apple arboriculture on the functions of human monocyte-derived macrophages (hMDMs). The results showed that exposure to certain pesticides may have toxic effects on immune cells and modulate antioxidant enzyme expression, while other pesticides had minimal influence.