The Therapeutic Effect of DA-6034 on Ocular Inflammation via Suppression of MMP-9 and Inflammatory Cytokines and Activation of the MAPK Signaling Pathway in an Experimental Dry Eye Model

Abstract

PURPOSE: To investigate the effect of DA-6034, 7-carboxymethyloxy-3',4',5-trimethoxy flavone, in experimentally-induced inflammatory dry eye in rabbit. In addition, to elucidate the mechanism of DA-6034, we evaluated the mitogen-activated protein kinase (MAPK) signaling pathway and transcriptional factor-kappa B (NF-kB) in corneal epithelial cells. METHODS: Rabbit lacrimal glands were injected with the T-cell mitogen concanavalin A (Con A). DA-6034 was then administered topically four times a day for six days starting 24 hr after Con A injection. Tear volume, tear function, MMP-9 and inflammatory cytokine levels in the lacrimal glands, and histological evaluation were subsequently assessed. In in vitro study, phosphorylated MAPKs (c-Jun NH2-terminal kinase (JNK) and p38 MAPK) and NF-kB were detected by enzyme-linked immunosorbent assay (ELISA) using human corneal epithelial cells. RESULTS: A single injection of Con A into the lacrimal glands induced a pronounced inflammatory response, caused elevated levels of MMP-9 and cytokines IL-8 and TGF-beta(1), and induced a decrease in tear volume and shortening of tear breakup time (TBUT). In this inflammation model of dry eye, DA-6034 clearly showed therapeutic efficacy by restoring tear function and inhibiting inflammatory responses after topical ocular application. Furthermore, DA-6034 attenuated the phosphorylation of JNK and p38 MAPK and inhibited NF-kB activation in a concentration-dependent manner in corneal epithelial cells. CONCLUSIONS: These results suggest that DA-6034 has the therapeutic effect in rabbit lacrimal gland inflammation model of dry eye and might be a potential treatment option for acute dry eye syndrome.