Mac-1 (cD11b/CD18) is an adhesion molecule on neutrophils and other leukocytes that mediates interaction with a number of different counter- ligands, including intercellular adhesion molecule-1 (ICAM-1). In vitro and in vivo studies have indicated that the binding of Mac-1 with parenchymal-cell-expressed ICAM-1 is a key event in mediating adhesion- dependent oxidative injury to the parenchymal cells by activated neutrophils. A program has therefore been initiated to develop inhibitors of this adhesion event. In preliminary studies, a phage-display library of random peptides was screened for sequences binding to purified Mac-1 protein, and a consensus peptide sequence was identified. A synthetic peptide representing this sequence was found to block Mac-1-dependent adhesion events in three different binding assays. During Phase I of the project, these observations will be extended by (i) verifying that the peptide is indeed interacting with Mac-1, rather than an associated or regulatory protein (using cross-linking experiments, and binding assays based on a fragment of Mac-1 expressed recombinantly in bacteria), and (ii) generating and screening a new phage display library, with the aim of identifying more potent versions of the original peptide.Proposed commercial application:The ultimate goal of the project is to produce a therapeutic agent useful for inhibiting the neutrophil-mediated organ damage associated with acute inflammatory events in disorders such as surgical ischemia-reperfusion.National Institute fo General Medical Sciences (NIGMS)
