Effects of aurothioglucose and dietary Se on glutathione S-transferase activities and glutathione concentrations in chick tissues

Loss of activity of the selenoenzyme thioredoxin reductase causes induction of hepatic heme oxygenase-1

The stress response enzyme heme oxygenase (HO)-1 is induced in livers of selenium-deficient rodents, probably to compensate for loss of certain selenoproteins. We sought to identify those selenoproteins. Selenium-replete mice with genetic deletion of selenoprotein P or glutathione peroxidase-1 did not have elevated hepatic HO activity, thus ruling out involvement of those selenoproteins in HO-1 induction by selenium deficiency. However, inhibition of thioredoxin reductase (TrxR) by a low dose of gold in the form of aurothioglucose led to induction of hepatic HO activity. Moreover, further induction by phenobarbital was observed. This HO-1 induction pattern is also seen in selenium-deficient mice. In the rat hepatoma cell line H4IIE, inhibition of TrxR by aurothioglucose or by 1-chloro-2,4-dinitrobenzene led to induction of HO-1. We conclude that loss of TrxR is responsible for the induction of HO-1 by selenium deficiency.

Dietary oxidative stress and the potentiation of viral infection

Oxidative stress is implicated in the pathogenesis of several viral infections, including hepatitis, influenza, and AIDS. Dietary oxidative stress due to either selenium or vitamin E deficiency increases cardiac damage in mice infected with a myocarditic strain of coxsackievirus B3. Such dietary oxidative stress also allows a normally benign (i.e., amyocarditic) coxsackievirus B3 to convert to virulence and cause heart damage. This conversion to virulence is due to a nucleotide sequence change in the genome of the benign virus, which then resembles more closely the nucleotide sequence of virulent strains. Although it has been known for many years that poor nutrition can affect host response to infection, this is the first report of host nutrition affecting the genetic sequence of a pathogen. Further research is needed to determine whether poor host nutrition plays any role in the emergence of new viral diseases via alterations in he genotype of an infectious agent.