Deregulation of microRNA-155 and its transcription factor NF-kB by polychlorinated biphenyls during viral infections.

Polychlorinated biphenyls (PCBs), and similar environmental contaminants, have been linked to virus outbreaks and increased viral induced mortality since the 1970s. Yet the mechanisms behind this increased susceptibility remain elusive. It has recently been illustrated that the innate immune viral detection system is tightly regulated by small non-coding RNAs, including microRNAs (miRNAs). For virus infections miRNA-155 expression is an important host response against infection, and deregulation of this miRNA is closely associated with adverse outcomes. Thus, we designed a targeted in vitro study using primary chicken fibroblasts, first exposed to a mixture of PCBs (Arochlor-1250) before being stimulated with a synthetic RNA virus (poly I:C), to determine if PCBs have the potential to deregulate miRNA-155. In this paper, we provide the first data for the deregulation of miRNA-155 when a host is exposed to a mixture of PCBs before a virus infection. Thus, we provide important evidence that PCBs can be involved in the deregulation of important miRNA pathways involved in the immune system; thereby demonstrating novel insights into the mechanism of PCB toxicity on the immune system.