Proresolving and Tissue-Protective Actions of Annexin A1-Based Cleavage-Resistant Peptides Are Mediated by Formyl Peptide Receptor 2/Lipoxin A4 Receptor

Endogenous mechanisms regulating the host response during inflammation resolution are critical in ensuring disposal of noxious stimuli and return to homeostasis. In this article, we engineered novel Annexin A1 (AnxA1)-based peptides, AnxA1(2-50), that displayed specific binding to the AnxA1 receptor (formyl peptide receptor 2/Lipoxin A(4) receptor [FPR2/ALX]; IC50 similar to 4 nM). Intravenous administration of AnxA12-50 markedly reduced (> 60%) leukocyte adhesion to postcapillary venules in wild type and Fpr1(-/-), but not Fpr2/Alx(-/-), mice. Generation of a metabolically stable form of this peptide (CR-AnxA1(2-50)), engineered by substituting a cleavage site shared by human proteinase 3 and neutrophil elastase, yielded an agonist that was resistant to neutrophil-mediated cleavage and displayed enhanced proresolving actions: accelerated resolution of self-limited inflammation and enhanced macrophage efferocytosis after sterile injury, when compared with AnxA1(2-50). These actions were retained with human primary leukocytes where CR-AnxA1(2-50) decreased neutrophil-endothelial interactions (similar to 25-45%), and stimulated neutrophil apoptosis and macrophage efferocytosis (similar to 45%). In murine cardiac ischemia/reperfusion injury, CR-AnxA1(2-50) elicited tissue-protective actions reducing infarct size (similar to 60%) and incidence of 24-h death. These results identify AnxA1(2-50) and CRAnxA1(2-50) as FPR2/ALX agonists that harness the proresolving actions of AnxA1, and thus may represent therapeutic tools for treatment of inflammatory conditions.