Polychlorinated Biphenyl Quinone Promotes Macrophage-Derived Foam Cell Formation

Polychlorinated biphenyls (PCBs) are organic environmental pollutants that are accused of various toxic effects. PCB exposure is widely believed to be associated with atherosclerosis, but the underlying mechanisms are unclear. Although PCBs are easily metabolized, there is rarely information on the effects of their metabolites on atherosclerosis. Currently, we evaluate the effect of 2,3,5-trichloro-6-phenyl-[1,4]-benzoquinone (PCB29-pQ) on the critical phase of atherosclerosis development, that is, the formation of macrophage-derived foam cells. We exposed Ox-LDL-induced RAW264.7 cells to 2.5 μM and 5 μM PCB29-pQ. Varieties of evidence have demonstrated that PCB29-pQ promotes foam cell formation and develops proinflammatory cascade and cell necroptosis. In detail, we observed that PCB29-pQ increased levels of total cholesterol (TC), free cholesterol (FC), triglyceride (TG), and cholesteryl ester (CE) by increasing the cholesterol influx and reducing the cholesterol efflux. Moreover, we found that PCB29-pQ induced inflammatory cytokines, such as tumor necrosis factor (TNF-α), interleukin 6 (IL-6), and IL-1β, released by activating the mitogen-activated protein kinase (MAPK)-nuclear factor kappa B (NF-κB) inflammatory pathway. In addition, we demonstrated that PCB29-pQ induced cell necroptosis via receptor interacting protein kinases 1 and 3 (RIPK1/3) and a mixed-lineage kinase domain-like (MLKL) pathway. Finally, the overproduction of reactive oxygen species (ROS) by PCB29-pQ played significant roles in these processes, which could be reversed with an antioxidant. Overall, our results indicated that PCB29-pQ promoted the macrophage formation of foam cells, inflammation, and cell necroptosis.