TNF receptor-associated factor 2 (TRAF2) is a key intracellular signaling mediator that acts downstream of not only TNF alpha but also various members of the TNF alpha superfamily. Here, we report that, despite their lack of TNF alpha signaling, TRAF2(-/-)TNF alpha(-/-) mice develop an inflammatory disorder characterized by autoantibody accumulation and organ infiltration by T cells with the phenotypes of activated, effector, and memory cells. RAG1(-/-) mice reconstituted with TRAF2(-/-)TNF alpha(-/-) bone marrow cells showed increased numbers of hyperactive T cells and rapidly developed progressive and eventually lethal inflammation. No inflammation was observed in RAG1(-/-) mice reconstituted with TRAF2(-/-)TNF alpha(-/-) T-cell receptor beta(-/-) or TRAF2(-/-)TNF alpha(-/-)NF kappa B-induced kinase(+/-) bone marrow cells. The pathogenic TRAF2(-/-)TNF alpha(-/-) T cells showed constitutive NF kappa B2p52 activation and produced elevated levels of T-helper 1 and T-helper 17 cytokines. Our results suggest that a regulatory circuit consisting of TRAF2-NF kappa B-induced kinase-NF kappa B2p52 is essential for the proper control of effector T-cell polarization and that loss of T-cell TRAF2 function induces constitutive NF kappa B2p52 activity that drives fatal autoimmune inflammation independently of TNF alpha signaling. The involvement of this regulatory circuit in controlling autoimmune responses highlights the delicate balance required to avoid paradoxical adverse events when implementing new targeted anti-inflammatory therapies.
Date:
2011-11
Relation:
Proceedings of the National Academy of Sciences of the United States of America. 2011 Nov;108(45):18354-18359.
