Antagonistic TNF receptor one-specific antibody (ATROSAB): receptor binding and in vitro bioactivity.

ABSTRACT:

Background

Selective inhibition of TNFR1 signaling holds the potential to greatly reduce the pro-inflammatory activity of TNF, while leaving TNFR2 untouched, thus allowing for cell survival and tissue homeostasis. ATROSAB is a humanized antagonistic anti-TNFR1 antibody developed for the treatment of inflammatory diseases.

Methodology/principal findings

The epitope of ATROSAB resides in the N-terminal region of TNFR1 covering parts of CRD1 and CRD2. By site-directed mutagenesis, we identified Arg68 and His69 of TNFR1 as important residues for ATROSAB binding. ATROSAB inhibited binding of (125)I-labeled TNF to HT1080 in the subnanomolar range. Furthermore, ATROSAB inhibited release of IL-6 and IL-8 from HeLa and HT1080 cells, respectively, induced by TNF or lymphotoxin alpha (LT?). Different from an agonistic antibody (Htr-9), which binds to a region close to the ATROSAB epitope but elicits strong TNFR1 activation, ATROSAB showed a negligible induction of IL-6 and IL-8 production over a broad concentration range. We further verified that ATROSAB, comprising mutations within the Fc region known to abrogate complement fixation and antibody-mediated cellular effector functions, indeed lacks binding activity for C1q, Fc?RI (CD64), Fc?RIIB (CD32b), and Fc?RIII (CD16) disabling ADCC and CDC.

Conclusions/significance

The data corroborate ATROSAB's unique function as a TNFR1-selective antagonist efficiently blocking both TNF and LT? action. In agreement with recent studies of TNFR1 complex formation and activation, we suggest a model of the underlying mechanism of TNFR1 inhibition by ATROSAB.

SUBMITTER: Richter F 

PROVIDER: S-EPMC3747052 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature