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Title: Structural basis for pH-insensitive inhibition of immunoglobulin G recycling by an anti-neonatal Fc receptor antibody

Abstract

The neonatal Fc receptor FcRn plays a critical role in the trafficking of IgGs across tissue barriers and in retaining high circulating concentrations of both IgG and albumin. Although generally beneficial from an immunological perspective in maintaining IgG populations, FcRn can contribute to the pathogenesis of autoimmune disorders when an abnormal immune response targets normal biological components. We previously described a monoclonal antibody (DX-2507) that binds to FcRn with high affinity at both neutral and acidic pH, prevents the simultaneous binding of IgG, and reduces circulating IgG levels in preclinical animal models. Here, we report a 2.5 Å resolution X-ray crystal structure of an FcRn–DX-2507 Fab complex, revealing a nearly complete overlap of the IgG–Fc binding site in FcRn by complementarity-determining regions in DX-2507. This overlap explains how DX-2507 blocks IgG binding to FcRn and thereby shortens IgG half-life by preventing IgGs from recycling back into circulation. Moreover, the complex structure explains how the DX-2507 interaction is pH-insensitive unlike normal Fc interactions and how serum albumin levels are unaffected by DX-2507 binding. These structural studies could inform antibody-based therapeutic approaches for limiting the effects of IgG-mediated autoimmune disease.

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
INDUSTRY
OSTI Identifier:
1409114
Resource Type:
Journal Article
Journal Name:
Journal of Biological Chemistry
Additional Journal Information:
Journal Volume: 292; Journal Issue: 42; Journal ID: ISSN 0021-9258
Publisher:
American Society for Biochemistry and Molecular Biology
Country of Publication:
United States
Language:
ENGLISH
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 59 BASIC BIOLOGICAL SCIENCES

Citation Formats

Kenniston, Jon A., Taylor, Brandy M., Conley, Gregory P., Cosic, Janja, Kopacz, Kris J., Lindberg, Allison P., Comeau, Stephen R., Atkins, Kateri, Bullen, Jameson, TenHoor, Christopher, Adelman, Burt A., Sexton, Daniel J., Edwards, Thomas E., and Nixon, Andrew E. Structural basis for pH-insensitive inhibition of immunoglobulin G recycling by an anti-neonatal Fc receptor antibody. United States: N. p., 2017. Web. doi:10.1074/jbc.M117.807396.
Kenniston, Jon A., Taylor, Brandy M., Conley, Gregory P., Cosic, Janja, Kopacz, Kris J., Lindberg, Allison P., Comeau, Stephen R., Atkins, Kateri, Bullen, Jameson, TenHoor, Christopher, Adelman, Burt A., Sexton, Daniel J., Edwards, Thomas E., & Nixon, Andrew E. Structural basis for pH-insensitive inhibition of immunoglobulin G recycling by an anti-neonatal Fc receptor antibody. United States. doi:10.1074/jbc.M117.807396.
Kenniston, Jon A., Taylor, Brandy M., Conley, Gregory P., Cosic, Janja, Kopacz, Kris J., Lindberg, Allison P., Comeau, Stephen R., Atkins, Kateri, Bullen, Jameson, TenHoor, Christopher, Adelman, Burt A., Sexton, Daniel J., Edwards, Thomas E., and Nixon, Andrew E. Wed . "Structural basis for pH-insensitive inhibition of immunoglobulin G recycling by an anti-neonatal Fc receptor antibody". United States. doi:10.1074/jbc.M117.807396.
@article{osti_1409114,
title = {Structural basis for pH-insensitive inhibition of immunoglobulin G recycling by an anti-neonatal Fc receptor antibody},
author = {Kenniston, Jon A. and Taylor, Brandy M. and Conley, Gregory P. and Cosic, Janja and Kopacz, Kris J. and Lindberg, Allison P. and Comeau, Stephen R. and Atkins, Kateri and Bullen, Jameson and TenHoor, Christopher and Adelman, Burt A. and Sexton, Daniel J. and Edwards, Thomas E. and Nixon, Andrew E.},
abstractNote = {The neonatal Fc receptor FcRn plays a critical role in the trafficking of IgGs across tissue barriers and in retaining high circulating concentrations of both IgG and albumin. Although generally beneficial from an immunological perspective in maintaining IgG populations, FcRn can contribute to the pathogenesis of autoimmune disorders when an abnormal immune response targets normal biological components. We previously described a monoclonal antibody (DX-2507) that binds to FcRn with high affinity at both neutral and acidic pH, prevents the simultaneous binding of IgG, and reduces circulating IgG levels in preclinical animal models. Here, we report a 2.5 Å resolution X-ray crystal structure of an FcRn–DX-2507 Fab complex, revealing a nearly complete overlap of the IgG–Fc binding site in FcRn by complementarity-determining regions in DX-2507. This overlap explains how DX-2507 blocks IgG binding to FcRn and thereby shortens IgG half-life by preventing IgGs from recycling back into circulation. Moreover, the complex structure explains how the DX-2507 interaction is pH-insensitive unlike normal Fc interactions and how serum albumin levels are unaffected by DX-2507 binding. These structural studies could inform antibody-based therapeutic approaches for limiting the effects of IgG-mediated autoimmune disease.},
doi = {10.1074/jbc.M117.807396},
journal = {Journal of Biological Chemistry},
issn = {0021-9258},
number = 42,
volume = 292,
place = {United States},
year = {2017},
month = {9}
}