Thiram modulates pro-inflammatory mediators in RAW 264.7 murine macrophage cells

Thiram (TMTD) is a widely used dithiocarbamate pesticide and fungicide and is one of potent contact allergens. In the light of known properties, thiram is also considered to be used as an inhibitor of inflammation. To investigate whether known pro-oxidative properties of thiram might be involved in immunogenic mechanisms, we carried out an in vitro study aimed at analysis of reactive oxygen species (ROS) generation, activation of NF-κB, expression of iNOS and COX-2, production of NO, PGE2 and IL-1β in murine macrophage cells (RAW 264.7). The cells were treated by thiram alone (0.5 µg/mL; 2 μM and 2 µg/mL; 8 μM) or concomitantly with bacterial endotoxin (LPS; 1 μg/mL). LPS was used as an endotoxin that triggers changes characteristic for inflammatory state of the cell. TMTD increased ROS production, level of oxidized glutathione (GSSG) and activated NF-κB. The consequence of NF-κB activation was the increase of IL-1β and NO production characteristic for inflammation. However, we did not observe changes in PGE2 concentration. We observed expression of iNOS, COX-2 proteins and NO and PGE2 production in macrophages treated with thiram concomitantly with LPS lower than those in cells stimulated with LPS alone. Thiram (2 µg/mL) decreased NF-κB activation and production of LPS-induced IL-1β. In conclusion, we demonstrated changes induced by TMTD characteristic for inflammation. Hence, it can be supposed that they may participate in the elicitation phase of allergic contact dermatitis induced by thiram. However, when TMTD acts concomitantly with LPS, it decreases the intensity of inflammation state in RAW 264.7.