A peptidomimetic antagonist of TNF-alpha-mediated cytotoxicity identified from a phage-displayed random peptide library.

Phage-displayed peptide libraries represent a vast collection of peptide sequences that can be used to identify novel therapeutic molecules. In this report, a 15-mer phage-displayed peptide library was used to identify potential TNF-alpha antagonists. After direct interaction of recombinant human TNF-alpha with the library, four randomly selected phage clones were shown to inhibit in a dose-dependent fashion both mouse and human TNF-alpha-induced cytotoxicity in vitro. DNA sequencing of the positive clones revealed a common amino acid sequence that does not bear any structural similarity to the known primary structures of the extracellular domains of either 55-kDa or 75-kDa TNF receptors. This sequence was synthesized, and the peptidomimotope was shown i) to bind to the recombinant human TNF-alpha using surface plasmon resonance (biosensor) technology and ii) to inhibit both recombinant mouse and human TNF-alpha-induced cytotoxicity in vitro in a dose-dependent fashion. These findings highlight the potential of phage-displayed random peptide libraries for the identification of novel low molecular antagonistic molecules that can block the biologic activities of TNF-alpha.