Rational design, analysis, and potential utility of GM-CSF antagonists.
Granulocyte-macrophage colony-stimulating factor (GM-CSF) is an important cytokine involved in many immune and inflammatory processes and is believed to act in the early stages of immune responses. GM-CSF stimulates antigen-presenting cells, enhancing antigen presentation and inducing macrophage tumoricidal activity. GM-CSF binds to specific cellular receptors that are potential targets for pharmacological design. Rational design of small-molecule mimics is an important approach to pharmacophore design. One of the strategies in the development of small-molecular mimics of larger polypeptyde ligands is analysis of alternative ligands that bind the same site as does the native ligand. Molecular studies of GM-CSF-receptor interactions have led to the development of interaction site analogs and the development of an "anti-anti-GM-CSF" recombinant antibody (rAb) analog of a site on GM-CSF important for biological activity and receptor binding. This rAb and a peptide derived from the rAb first complementarity determining region (CDR) sequence bind to a monoclonal anti-GM-CSF antibody that mimics the GM-CSFR alpha chain, compete with GM-CSF for binding to GM-CSF receptor alpha chain (GM-CSFR alpha), and are specific biological antagonists. Molecular modeling of the rAb suggests structural similarity with a site previously implicated in GM-CSF binding to the GM-CSFR alpha. Two cyclic peptides, 1785 and 1786, also were developed on the basis of structural analysis of the GM-CSF region mimicked by anti-anti-GM-CSF recombinant antibody (rAb) 23.2. These peptides were designed to mimic structurally the positions of specific residues on the B and C helicies of human GM-CSF implicated in receptor binding and bioactivity. Both 1785 and 1786 were recognized specifically by polyclonal anti-GM-CSF antibody. 1786 also competitively inhibited binding of GM-CSF to the GM-CSF receptor and demonstrated antagonist bioactivity, as shown by its reversal of GM-CSF's ability to inhibit apoptosis of the GM-CSF-dependent cell line MO7E. These studies support the role of residues on the GM-CSF B and C helicies in receptor binding and bioactivity and suggest strategies for mimicking binding sites on four-helix bundle proteins with cyclic peptides.
Monfardini
C
C
Department of Medicine, University of Pennsylvania, Philadelphia 19103, USA.
Kieber-Emmons
T
T
VonFeldt
J M
JM
Godillot
A P
AP
Voet
D
D
Weiner
D B
DB
Williams
W V
WV
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D001665:Binding Sites; D015195:Drug Design; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000037:antagonists & inhibitors*; D006801:Humans; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology
D000906:Antibodies; D010455:Peptides; D011994:Recombinant Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor