Yesterday I saw a fascinating Nature article (Nature doi:10.1038/nature13323): Low doses of LPS in mice induce LPS tolerance. The underlying mechanism involve – according to the authors – the AhR and two different dioxigenases, tryptophan 2,3-dioxygenase and indoleamine 2,3-dioxygenase. This is related to endotoxic shock a still devasting condition.