Immunomodulatory host defense peptides (HDPs) are considered to be lead compounds for novel anti-sepsis and anti-inflammatory agents. However， development of drugs based on HDPs has been hampered by problems with toxicity and low bioavailability due to in vivo proteolysis. Here， a subclass of proteolytically stable HDP mimics consisting of lipidated α-peptide/β-peptoid oligomers was investigated for their effect on neutrophil function. The most promising compound， Pam-(Lys-βNSpe)6-NH2， was shown to inhibit formyl peptide receptor 2 (FPR2) agonist-induced neutrophil granule mobilization and release of reactive oxygen species. The potency of Pam-(Lys-βNSpe)6-NH2 was comparable to that of PBP10， the ... More
Immunomodulatory host defense peptides (HDPs) are considered to be lead compounds for novel anti-sepsis and anti-inflammatory agents. However， development of drugs based on HDPs has been hampered by problems with toxicity and low bioavailability due to in vivo proteolysis. Here， a subclass of proteolytically stable HDP mimics consisting of lipidated α-peptide/β-peptoid oligomers was investigated for their effect on neutrophil function. The most promising compound， Pam-(Lys-βNSpe)6-NH2， was shown to inhibit formyl peptide receptor 2 (FPR2) agonist-induced neutrophil granule mobilization and release of reactive oxygen species. The potency of Pam-(Lys-βNSpe)6-NH2 was comparable to that of PBP10， the most potent FPR2-selective inhibitor known. The immunomodulatory effects of structural analogs of Pam-(Lys-βNSpe)6-NH2 emphasized the importance of both the lipid and peptidomimetic parts. By using imaging flow cytometry in primary neutrophils and FPR-transfected cell lines， we found that a fluorescently labeled analog of Pam-(Lys-βNSpe)6-NH2 interacted selectively with FPR2. Furthermore， the interaction between Pam-(Lys-βNSpe)6-NH2 and FPR2 was found to prevent binding of the FPR2-specific activating peptide agonist Cy5-WKYMWM， while the binding of an FPR1-selective agonist was not inhibited. To our knowledge， Pam-(Lys-βNSpe)6-NH2 is the first HDP mimic found to inhibit activation of human neutrophils via direct interaction with FPR2. Hence， we consider Pam-(Lys-βNSpe)6-NH2 to be a convenient tool in the further dissection of the role of FPR2 in inflammation and homeostasis as well as for investigation of the importance of neutrophil stimulation in anti-infective therapy involving HDPs.
