PMID: 23504311

Authors:

Liang S, Dai J, Hou S, Su L, Zhang D, Guo H, Hu S, Wang H, Rao Z, Guo Y, Lou Z

Title:

Structural basis for treating tumor necrosis factor alpha (TNFalpha)-associated diseases with the therapeutic antibody infliximab.

Journal:

J Biol Chem. 2013 May 10;288(19):13799-807. doi: 10.1074/jbc.M112.433961. Epub, 2013 Mar 15.

Abstract:

BACKGROUND: Although infliximab has high efficacy in treating TNFalpha-associated diseases, the epitope on TNFalpha remains unclear. RESULTS: The crystal structure of the TNFalpha in complex with the infliximab Fab is reported at a resolution of 2.6 A. CONCLUSION: TNFalpha E-F loop plays a crucial role in the interaction. SIGNIFICANCE: The structure may lead to understanding the mechanism of mAb anti-TNFalpha Monoclonal antibody (mAb) drugs have been widely used for treating tumor necrosis factor alpha (TNFalpha)-related diseases for over 10 years. Although their action has been hypothesized to depend in part on their ability to bind precursor cell surface TNFalpha, the precise mechanism and the epitope bound on TNFalpha remain unclear. In the present work, we report the crystal structure of the infliximab Fab fragment in complex with TNFalpha at a resolution of 2.6 A. The key features of the TNFalpha E-F loop region in this complex distinguish the interaction between infliximab and TNFalpha from other TNF-receptor structures, revealing the mechanism of TNFalpha inhibition by overlapping with the TNFalpha-receptor interface and indicating the crucial role of the E-F loop in the action of this therapeutic antibody. This structure also indicates the formation of an aggregated network for the activation of complement-dependent cytolysis and antibody-dependent cell-mediated cytotoxicity, which result in development of granulomatous infections through TNFalpha blockage. These results provide the first experimental model for the interaction of TNFalpha with therapeutic antibodies and offer useful information for antibody optimization by understanding the precise molecular mechanism of TNFalpha inhibition.