Abstract Oxidation of arachidonic acid generates biologically active derivatives that play a critical role in shaping the inflammatory response. One such derivative, carboxypropylpyrrole (CPP), is a stable end product of arachidonic acid oxidation that has been previously described and detected in inflamed tissues; however, its pathophysiological contribution to inflammation has not been investigated. CPP forms covalent adducts with the extracellular matrix and plasma proteins, altering their biochemical properties and receptor-binding characteristics. Here, we examined how CPP formation impacts neutrophil migration during acute inflammation. Using cell adhesion assays and biolayer interferometry, we identified integrins αMβ2 and αDβ2 as receptors for CPP-modified proteins. Among these, αMβ2 emerged as the primary binding partner on neutrophils, reflecting the low expression of αDβ2 in this cell subset. CPP binding to αMβ2 was mediated by the αM I-domain, required the integrin’s high-affinity conformation, and partially overlapped with the classical fibrinogen-binding site. Human and mouse neutrophil swarming assays toward Candida albicans revealed that CPP-modified proteins behave as a unique substrate, unlike classical extracellular matrix protein laminin or inflammatory ligand fibrinogen. While fibrinogen and laminin support cell adhesion and robust migration, CPP-modified proteins promote strong neutrophil adhesion, but inhibit cell migration. CPP deposition within migratory substrates further reduced neutrophil migration in a concentration-dependent manner. Neutrophils isolated from αM-deficient mice confirmed the essential role of αMβ2 in these CPP-mediated effects. These findings suggest that arachidonic acid oxidation products, through selective interaction with αMβ2, regulate neutrophil adhesion and migration and may act as endogenous modulators of the inflammatory response.
Casteel et al. (Sun,) studied this question.