Transcriptomics identifies differences between ultrapure non-dioxin-like polychlorinated biphenyls (PCBs) and dioxin-like PCB126 in cultured peripheral blood mononuclear cells.

Polychlorinated biphenyls (PCBs) remain ubiquitously present in human lipids despite the ban on their production and use. Their presence can be chemically monitored in peripheral blood samples of the general population. We tested whether in vitro exposure to different PCB congeners induced different gene expression profiles in peripheral blood cells. We have isolated peripheral blood mononuclear cells (PBMC) from whole blood of 8 healthy individuals and exposed these cells in vitro to individual non-dioxin-like (NDL)-PCB congeners (PCB52, 138 or 180; 10μM) or dioxin-like (DL)-PCB congener PCB126 (1μM) during 18h. Differential gene expression response was measured using Agilent whole-human genome microarrays. Two-way ANOVA analysis of the data showed that both gender and PCB exposure are important factors influencing gene expression responses in blood cells. Hierarchical cluster analysis of genes influenced by PCB exposure, revealed that DL-PCB126 induced a different gene expression response compared to the NDL-PCBs. Biological interpretation of the results revealed that exposure to PCB126 induced the AhR signaling pathway, whereas the induction of nuclear receptor pathways by the NDL-PCBs was limited in blood cells. Nevertheless, molecular responses of blood cells to individual PCB congeners revealed significantly expressed genes that play a role in biological functions and processes known to be affected by PCB exposure in vivo. Observed gene expression changes in this in vitro model were found to be related to hepatotoxicity, immune and inflammatory response and disturbance of lipid and cholesterol homeostasis.