PNAS 2007-11-20

3-Hydroxyanthranilic acid inhibits PDK1 activation and suppresses experimental asthma by inducing T cell apoptosis.

Tomoko Hayashi, Ji-Hun Mo, Xing Gong, Cyprian Rossetto, Angela Jang, Lucinda Beck, Gregory I Elliott, Irina Kufareva, Ruben Abagyan, David H Broide, Jongdae Lee, Eyal Raz

Index: Proc. Natl. Acad. Sci. U. S. A. 104 , 18619-24, (2007)

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Abstract

3-Hydroxyanthranilic acid (HAA), a compound generated during tryptophan metabolism initiated by indoleamine 2,3-dioxygenase, is known to induce T cell death, but its molecular target is not known. Here we report that HAA inhibits NF-kappaB activation upon T cell antigen receptor engagement by specifically targeting PDK1. Inhibition of NF-kappaB by HAA leads to dysfunction and cell death of activated Th2 cells, which in turn suppresses experimental asthma. Inhibition of NF-kappaB and induction of apoptosis is specific to CD4 T cells because HAA does not inhibit NF-kappaB activation or induce cell death upon Toll-like receptor 4 stimulation in dendritic cells. Thus, HAA is a natural inhibitor that restrains T cell expansion and activation.