Coxsackievirus B3 Infection and Host Defence Responses Change the Metabolism of PBDE

Abstract: It has been suggested that the rising amounts of chemicals in the environment may affect host resistance and increase susceptibility to infections. Studies have also shown that infections can change the toxicity of pollutants. The aim of this thesis was to study interactions between environmental pollutant exposure in terms of polybrominated diphenyl ethers (PBDE) and a common human coxsackievirus B3 (CVB3) infection adapted to Balb/c mice. The studies focused on virus levels, cytokines, metabolising cytochrome P450 (CYP) enzymes and tissue distribution of PBDE.A novel finding was an organ-specific effect of CVB3 infection on the metabolising capacity of PBDE. The PBDE metabolising enzyme CYP2B10 was down-regulated by the CVB3 infection in the liver, up-regulated in the lungs, but not affected in the pancreas. Accordingly, CVB3 infection increased the concentration of PBDE in the livers of infected mice. However, serum levels of PBDE were not affected by the infection, indicating that serum does not reflect the actual organ exposure of PBDE in infected individuals. The change in metabolising capacity was likely mediated by infection-induced cytokines and associated effects on the nuclear factor-?B (NF-?B) pathway.PBDE drastically decreased serum levels of several cytokines and chemokines, an event that may create a slot for viruses to replicate. Accordingly, some results show that infected mice exposed to a high dose of PBDE had higher virus levels than mice exposed to a low dose.In conclusion, infected individuals showed organ-specific changes in metabolism and tissue levels of PBDE, which potentially could change the toxicity of PBDE. PBDE also seems to affect the fate of the infection. NF-?B activated pathways may mediate one possible mechanism underlying these effects. Thus, further investigations of this pathway are warranted. In addition, future studies should address how PBDE exposure affects viral replication.