CD34+ derived macrophage and dendritic cells display differential responses to paraquat

Paraquat (PQ) is a redox cycling herbicide known for its acute toxicity in humans. Airway parenchymal cells have been identified as primary sites for PQ accumulation, tissue inflammation and cellular injury. However, the role of immune cells in PQ induced tissue injury is largely unknown. To explore this further, primary cultures of human CD34+ stem cell derived macrophages (MCcd34) and dendritic cells (DCcd34) were established and characterised using RNA-Seq profiling. The impact of PQ on DCcd34 and MCcd34 cytotoxicity revealed increased effect within DCcd34 cultures. PQ toxicity mechanisms were examined using sub-cytotoxic concentrations and TempO-seq transcriptomic assays. Comparable increases for several stress response pathway (NFE2L2, NF-kB and HSF) dependent genes were observed across both cell types. Interestingly, PQ induced unfolded protein response (UPR), p53, Irf and DC maturation genes in DCcd34 but not in MCcd34. Further exploration of the immune modifying potential of PQ was performed using the common allergen house dust mite (HD). Co-treatment of PQ and HD resulted in enhanced inflammatory responses within MCcd34 but not DCcd34. These results demonstrate immune cell type differential responses to PQ, that may underlie aspects of acute toxicity and susceptibility to inflammatory disease. •Paraquat induces inflammatory and oxidative events in immune cells.•Paraquat prompts selective induction of several pathways in dendritic cells.•Paraquat and dust mite co-exposure enhances inflammatory response in macrophages.•These results provide insight into paraquat mechanisms of toxicity.