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

Abstract

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 μmol.L^-1). We showed that chlorpyrifos, thiacloprid, thiophanate, boscalid, and captan had little toxic effect at the tested concentrations, while dithianon had low-cytotoxicity at 10 μmol.L^-1. While boscalid showed no effect on hMDMs function, thiophanate (0.01 μmol.L^-1) stimulated with TPA and thiacloprid (1, 10 μmol.L^-1) stimulated with zymosan activated ROS production. Chlorpyrifos, dithianon, and captan inhibited ROS production and TNF-α, IL-1β pro-inflammatory cytokines. We established that dithianon (0.01-1 μmol.L^-1) and captan (0.1, 1 μmol.L^-1) induced mRNA expression of NQO1 and HMOX1 antioxidant enzymes. Dithianon also induced the mRNA expression of catalase, superoxide dismutase-2 at 10 μmol.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.

Keywords: Antioxidant molecules; Cytokines; Macrophages; Oxidative burst; Pesticides.