Principles of antibody-mediated TNF receptor activation

Abstract

From the beginning of research on receptors of the tumor necrosis factor (TNF) receptor superfamily (TNFRSF), agonistic antibodies have been used to stimulate TNFRSF receptors in vitro and in vivo. Indeed, CD95, one of the first cloned TNFRSF receptors, was solely identified as the target of cell death-inducing antibodies. Early on, it became evident from in vitro studies that valency and Fcγ receptor (FcγR) binding of antibodies targeting TNFRSF receptors can be of crucial relevance for agonistic activity. TNFRSF receptor-specific antibodies of the IgM subclass and secondary cross-linked or aggregation prone dimeric antibodies typically display superior agonistic activity compared with dimeric antibodies. Likewise, anchoring of antibodies to cell surface-expressed FcγRs potentiate their ability to trigger TNFRSF receptor signaling. However, only recently has the relevance of oligomerization and FcγR binding for the in vivo activity of antibody-induced TNFRSF receptor activation been straightforwardly demonstrated in vivo. This review discusses the crucial role of oligomerization and/or FcγR binding for antibody-mediated TNFRSF receptor stimulation in light of current models of TNFRSF receptor activation and especially the overwhelming relevance of these issues for the rational development of therapeutic TNFRSF receptor-targeting antibodies.

Advancing targeted co-stimulation with antibody-fusion proteins by introducing TNF superfamily members in a single-chain format

“…The latter is efficiently supported either by a membrane-anchored, i.e., cell surface presentation of the ligand or its oligomerization in soluble form, depending on the activation requirement of the particular TNFSF-receptor. 28 It is conceivable that stabilization of the trimeric ligand conformation by the single-chain format in the scFv-scTNFSF positively supports this process in both phases and targeting the fusion protein to the tumor cell via one scFv unit is sufficient for efficient cell surface presentation of the ligand. From a targeting point of view, it remains to be seen how differences in antibody binding capacity will reflect in the biodistribution pattern of the fusion proteins in vivo.…”

Duokines: a novel class of dual-acting co-stimulatory molecules acting in cis or trans

“…However, efficient activation of the receptors often requires receptor clustering induced by binding of more than one ligand displayed on the cell membrane. 10,11 Here, antibodies are limited due to their bivalent binding mode and require binding to nearby Fcγ receptor-bearing cells for clustering and signal induction.…”

Binding Studies of TNF Receptor Superfamily (TNFRSF) Receptors on Intact Cells

“…In particular, values derived from cell free assays are often quite different from binding parameters obtained by cellular binding studies (Table 1). Presumably, this dissatisfying situation is mainly caused by the fact that the formation of TNFSF ligand-TNFRSF receptor complexes on the cell surface is controlled by several cell intrinsic factors, such as dynamic self-assembly of TNFRSF receptors in the absence of ligand and interactions with the cytoskeleton that cannot be adequately gathered by cell-free techniques (8).…”