Effects of Hyaluronic Acid on the Polymorphonuclear Leukocyte (PMN) Release of Active Oxygen and Protection of Bovine Corneal Endothelial Cells from Activated PMNs

The goal of this study was to evaluate the function of hyaluronic acid (HA) on the active oxygen release from polymorphonuclear leukocytes (PMNs) and the protective effect of bovine corneal endothelial cells (BCEC) from activated PMNs. We used HA with three different molecular weights (MW 700,000, 2,000,000, and 4,000,000) and five different concentrations (0, 0.1, 1, 2, and 3 mg/ml). We evaluated the amount of released superoxide from activated PMNs by using dismutase-inhibitable ferricytochrome C reduction. To compare the property and protective effect of HA with those of other viscoelastic substances, we used the same concentration of methylcellulose. HA suppressed superoxide release from PMNs and protected BCEC from activated PMNs in a dose-dependent, rather than a molecular weight-dependent, manner. The effect of HA reached almost a plateau at concentration above 2 mg/ml. However, methylcellulose, another viscoelastic substance, showed a similar effect. Therefore, it seems that the suppression of superoxide released from PMNs is not a property that is unique to HA, but is a general property of viscoelastic substances. Our results indicate that the action mechanism of HA proceeds not only through cell surface HA-receptor. We think that HA also acts as a physical barrier and/or a scavenger of superoxide.