WRW4 (trifluoroacetate salt) (Synonyms: Trp-Arg-Trp-Trp-Trp-Trp-CONH2, Trp-Arg-Trp-Trp-Trp-Trp-NH2, WRWWWW-NH2)

WRW4 is a peptide antagonist of formyl peptide receptor 2 (FPR2; IC₅₀ = 0.23 µM) and FPR3, previously known as FPR-like 1 (FPRL1) and FPRL2, respectively.^1,2 It inhibits increases in intracellular calcium and chemotaxis induced by the FPR1 and FPR2 agonist WKYMVm in RBL-2H3 cells expressing FPR2 and by the FPR3 agonist F2L in isolated human monocytes when used at a concentration of 10 µM. WRW4 (10 µM) also prevents the production of superoxide induced by amyloid-β (1-42) in isolated human neutrophils.¹ In vivo, WRW4 (1 mg/kg) increases lung edema and bronchoalveolar lavage fluid (BALF) protein levels in the absence and presence of the antibiotic ceftriaxone in a mouse model of acute lung injury induced by S. pneumoniae.³

1.Bae, Y.-S., Lee, H.Y., Jo, E.J., et al.Identification of peptides that antagonize formyl peptide receptor-like 1-mediated signalingJ. Immunol.173(1)607-614(2004) 2.Shin, E.H., Lee, H.-Y., Kim, S.D., et al.Trp-Arg-Trp-Trp-Trp-Trp antagonizes formyl peptide receptor like 2-mediated signalingBiochem. Biophys. Res. Commun.341(4)1317-1322(2006) 3.Siegel, E.R., Croze, R.H., Fang, X., et al.Inhibition of the lipoxin A4 and resolvin D1 receptor impairs host response to acute lung injury caused by pneumococcal pneumonia in miceAm. J. Physiol. Lung Cell Mol. Physiol.320(6)L1085-L1092(2021)