RESUMO
AIM: To investigate the expression and possible role of the autophagy related protein p62 and LC3 in the retina based on a rat model of acute ocular hypertension. METHODS: Fifty rats were randomized into five groups: control group A, B, C, and D. Groups A to D all received normal saline perfusion into the anterior chamber with pressure of 80 mm Hg for one hour, and retina tissue was obtained at 6, 12, 24 and 48h after perfusion respectively, to investigate the activation of autophagy following ischemia-reperfusion. The distribution and semi-quantification of autophagy related protein p62 and LC3 in the retina were detected using immunohistochemistry technique. The expression level of these two proteins was evaluated using Western blot. RESULTS: The number of retinal ganglion cells (RGCs) decreased with increasing reperfusion time, and significant reduction in the retinal thickness was observed 48h after perfusion. In normal adult rats, LC3 protein was mainly expressed in the ganglion cell layer (GCL), and p62 protein was expressed in the nerve fiber layer (NFL), GCL, inner plexiform layer (IPL), inner nuclear layer (INL) and outer plexiform layer (OPL). In comparison to the control group, the expression level of LC3- II was higher in all the experimental groups (P<0.05), with the peak expression at 12h after reperfusion. Additionally, the expression level of p62 was higher in all the experimental groups than the control (P<0.05, except for group A), with the peak level occurred 24h after reperfusion. CONCLUSION: Both p62 and LC3 show low level and uneven expression in the retina of normal adult rats. Acute ocular hypertension can lead to upregulation of LC3- II and p62 expression in the retina. Autophagy flux is damaged 12h after reperfusion, potentially resulting in further loss of RGCs.
RESUMO
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.