title: A CXCL8 receptor antagonist based on the structure of N-acetyl-proline-glycine-proline.
abstract: A role for the collagen-derived tripeptide, N-acetyl proline-glycine-proline (NAc-PGP), in neutrophil recruitment in chronic airway inflammatory diseases, including COPD and cystic fibrosis, has recently been delineated. Due to structural similarity to an important motif for interleukin-8 (CXCL8) binding to its receptor, NAc-PGP binds to CXCR1/2 receptors, leading to neutrophil activation and chemotaxis. In an effort to develop novel CXCL8 antagonists, we describe the synthesis of four chiral isomers of NAc-PGP (NAc-L-Pro-Gly-L-Pro (LL-NAc-PGP), NAc-L-Pro-Gly-D-Pro (LD-NAc-PGP), NAc-D-Pro-Gly-L-Pro (DL-NAc-PGP), and NAc-D-Pro-Gly-D-Pro (DD-NAc-PGP)), characterize them by circular dichroism and NMR spectroscopy, compare their structures to the equivalent region of CXCL8, and test them as potential antagonists of ll-NAc-PGP and CXCL8. We find that LL-NAc-PGP superimposes onto the CXCR1/2 contacting E(29)S(30)G(31)P(32) region of CXCL8 (0.59A rmsd for heavy atoms). In contrast, DD-NAc-PGP has an opposing orientation of key functional groups as compared to the G(31)P(32) region of CXCL8. As a consequence, DD-NAc-PGP binds CXCR1/2, as demonstrated by competition with radiolabeled CXCL8 binding in a radioreceptor assay, yet acts as a receptor antagonist as evidenced by inhibition of CXCL8 and LL-NAc-PGP mediated neutrophil chemotaxis. The ability of DD-NAc-PGP to prevent the activation of CXC receptors indicates that DD-NAc-PGP may serve as a lead compound for the development of CXCR1/2 inhibitors. In addition, this study further proves that using a different technical approach, namely preincubation of NAc-PGP instead of simultaneous addition of NAc-PGP with radiolabeled CXCL8, the direct binding of NAc-PGP to the CXCL8 receptor is evident.
authors: Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine and UAB Lung Health Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA. plj@uab.edu
authors: Patricia L
authors: PL
authors: Jackson
authors: Brett D
authors: BD
authors: Noerager
authors: Michael J
authors: MJ
authors: Jablonsky
authors: Matthew T
authors: MT
authors: Hardison
authors: Bryan D
authors: BD
authors: Cox
authors: James C
authors: JC
authors: Patterson
authors: Boopathy
authors: B
authors: Dhanapal
authors: J Edwin
authors: JE
authors: Blalock
authors: Donald D
authors: DD
authors: Muccio
mesh_terms: D001667:Binding, Competitive; D002634:Chemotaxis, Leukocyte / Q000187:drug effects; D002942:Circular Dichroism; D015195:Drug Design; D004355:Drug Stability; D018922:HL-60 Cells; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D056004:Molecular Dynamics Simulation; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D011487:Protein Conformation; D053700:Receptors, Interleukin-8 / Q000037:antagonists & inhibitors*; D013329:Structure-Activity Relationship
chemical_list: D016209:Interleukin-8; C428643:N-acetyl-proline-glycine-proline; D009842:Oligopeptides; D053700:Receptors, Interleukin-8