Conjugates bearing multiple formyl-methionyl peptides display enhanced binding to but not activation of phagocytic cells.
N-Formyl-methionyl peptides can specifically bind to surface receptors on phagocytic cells. A single copy of N-formyl-methionine-leucine-phenylalanine (fMLF) covalently linked to a poly(ethylene glycol)-based polymer displayed reduced binding avidity (K(d) = 190 nM) for differentiated HL-60 cells relative to free fMLF (K(d) = 28 nM). Increasing the number of fMLF residues (up to eight) attached to a single polymer results in enhanced avidity for these cells (K(d) = 0.18 nM), which appears to be independent of whether the polymer backbone is linear or branched. However, no conjugate showed enhanced ability to activate phagocytic cells, relative to the free peptide (EC(50) = 5 nM), as measured by transient stimulation of release of calcium ions from intracellular stores into the cytoplasm. A polymer bearing four fMLF and four digoxigenin residues showed specific enhancement in binding to differentiated HL-60 cells and mouse peritoneal macrophages in situ relative to a polymer lacking fMLF; no such enhancement was seen in binding to receptor-negative lymphocytic Jurkat cells. These results suggest that multiple fMLF residues linked to a drug-delivery polymer can be used to target appended drugs to phagocytic cells with relatively little toxicity due to cellular activation.
Pooyan
Shahriar
S
Department of Chemistry, Rutgers University, Rutgers, Piscataway, New Jersey 08854, USA.
Qiu
Bo
B
Chan
Marion M
MM
Fong
Dunne
D
Sinko
Patrick J
PJ
Leibowitz
Michael J
MJ
Stein
Stanley
S
D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation; D002460:Cell Line; D004337:Drug Carriers / Q000737:chemistry; D016503:Drug Delivery Systems / Q000379:methods; D018922:HL-60 Cells; D006801:Humans; D019169:Jurkat Cells; D008262:Macrophage Activation / Q000187:drug effects*; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000378:metabolism*; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology*; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D011092:Polyethylene Glycols / Q000737:chemistry; D011485:Protein Binding / Q000187:drug effects
D004337:Drug Carriers; D010455:Peptides; D011092:Polyethylene Glycols; D009240:N-Formylmethionine Leucyl-Phenylalanine; D002118:Calcium