Hyaluronic acid increases MMP-2 and MMP-9 expressions in cultured trabecular meshwork cells from patients with primary open-angle glaucoma

PURPOSE A depletion of hyaluronic acid (HA) in patients' eyes may be associated with primary open-angle glaucoma (POAG), but the exact mechanism remains unclear. We investigated the effect of HA on the expression of matrix metalloproteinases (MMP-2 and MMP-9) in cultured trabecular meshwork cells. METHODS Trabecular meshwork cells were cultured from trabecular tissues obtained from the POAG patients aged 23 to 45. The mRNA expression of MMP-2 and MMP-9 was determined by reverse transcription-polymerase chain reaction, and the protein expression of MMP-2 and MMP-9 by gelatin zymography analysis and qualified by the gel electrophoresis image analysis in different HA concentrations. RESULTS The expression of MMP-2 and MMP-9 by the two methods significantly increased with HA concentration in a dose-response manner. Mean values of the MMP-2 expression by the gelatin zymography analysis were 176, 264, 353, and 448 mg/ml, and mean values of the MMP-9 expression were 547, 659, 895, and 1,147 mg/ml, for HA concentration level of 0, 1, 3, and 6 mg/ml, respectively. CONCLUSIONS In POAG trabecular meshwork cells, the level of HA concentration increases the activities of MMP-2 and MMP-9. The lack of HA in aqueous humor can result in a reduction in activities of MMPs and therefore may be involved in the pathogenesis of POAG.