DS-70, a novel and potent alpha(4) integrin antagonist, is an effective treatment for experimental allergic conjunctivitis in guinea pigs

BACKGROUND AND PURPOSE Allergic conjunctivitis is an eye inflammation that involves the infiltration of immune cells into the conjunctiva via cell surface-adhesion receptors, such as integrin alpha(4)beta(1). These receptors interact with adhesion molecules expressed on the conjunctival endothelium and may be a target to treat this disease. We synthesized DS-70, a novel alpha/beta-peptidomimetic alpha(4) integrin antagonist, to prevent the conjunctival infiltration of immune cells and clinical symptoms in a model of allergic conjunctivitis. EXPERIMENTAL APPROACH In vitro, DS-70 was pharmacologically characterized using a scintillation proximity procedure to measure its affinity for alpha(4)beta(1) integrin, and its effect on cell adhesion mediated by different integrins was also evaluated. The effects of DS-70 on vascular cell adhesion molecule-1 (VCAM-1)-mediated degranulation of a human mast cell line and an eosinophilic cell line, which both express alpha(4)beta(1), and on VCAM-1-mediated phosphorylation of ERK 1/2 in Jurkat E6.1 cells were investigated. Effects of DS-70 administered in the conjunctival fornix of ovalbumin-sensitized guinea pigs were evaluated. KEY RESULTS DS-70 bound to integrin alpha(4)beta(1) with nanomolar affinity, prevented the adhesion of alpha(4) integrin-expressing cells, antagonized VCAM-1-mediated degranulation of mast cells and eosinophils and ERK 1/2 phosphorylation. Only 20% was degraded after an 8h incubation with serum. DS-70 dose-dependently reduced the clinical symptoms of allergic conjunctivitis, conjunctival alpha(4) integrin expression and conjunctival levels of chemokines and cytokines in ovalbumin-sensitized guinea pigs. CONCLUSIONS AND IMPLICATIONS These findings highlight the role of alpha(4) integrin in allergic conjunctivitis and suggest that DS-70 is a potential treatment for this condition.