Selective inhibition of N-formylpeptide-induced neutrophil activation by carbamate-modified peptide analogues.
Stimulation of the leukocyte N-formylpeptide receptor (FPR) induces chemotaxis, cell adhesion, free radical release, and degranulation, responses associated with infection and inflammation. Under conditions where continuous activation of the receptor prevails, neutrophil-dependent tissue damage ensues. Antagonists of the FPR have potential for use as diagnostic and therapeutic agents. Hence, we have synthesized and evaluated a series of amino-terminal carbamate analogues of the peptide Met-Leu-Phe (MLF) in order to determine the structural requirements for imparting agonist or antagonist activity at the human neutrophil FPR. Peptides were evaluated in three in vitro assays: receptor binding, superoxide anion release, and cell adhesion. Unbranched carbamates (methoxycarbonyl, ethoxycarbonyl, and n-butyloxycarbonyl) resulted in agonist activity, whereas branched carbamates (iso-butyloxycarbonyl, tert-butyloxycarbonyl, and benzyloxycarbonyl) were antagonists. The peptide antagonists were more potent inhibitors of superoxide anion release than cell adhesion by 4-7-fold. When iso-butyloxycarbonyl-MLF (i-Boc-MLF) was further modified at the carboxy terminus with Lys, antagonist potency was retained but without functional selectivity. Further C-terminal modification with the radionuclide linker diethylenetriaminepentaacetic acid did not alter the potency of i-Boc-MLFK. These results indicate that the switch from agonist to antagonist activity can be achieved by modifying the overall size and shape of the amino-terminal group; that modifications at both the amino and carboxy termini can alter the functional selectivity of the peptide; and that modifications can be tolerated at the carboxy terminus to allow for development of an antagonist for diagnostic applications.
Derian
C K
CK
R. W. Johnson Pharmaceutical Research Institute, Spring House, Pennsylvania 19477, USA.
Solomon
H F
HF
Higgins
J D
JD
Beblavy
M J
MJ
Santulli
R J
RJ
Bridger
G J
GJ
Pike
M C
MC
Kroon
D J
DJ
Fischman
A J
AJ
D000328:Adult; D000595:Amino Acid Sequence; D002219:Carbamates / Q000737:chemistry*; D002448:Cell Adhesion / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology; D006801:Humans; D008969:Molecular Sequence Data; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000031:analogs & derivatives*; D018375:Neutrophil Activation / Q000187:drug effects*; D009504:Neutrophils / Q000502:physiology; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic / Q000819:agonists* / Q000037:antagonists & inhibitors* / Q000378:metabolism; D018000:Receptors, Peptide / Q000819:agonists* / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013329:Structure-Activity Relationship; D013481:Superoxides / Q000378:metabolism
D002219:Carbamates; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic; D018000:Receptors, Peptide; D013481:Superoxides; D009240:N-Formylmethionine Leucyl-Phenylalanine