Selective laser trabeculoplasty (SLT) can increase the outflow of aqueous humor and reduce the intraocular pressure of patients with open angle glaucoma, but its mechanism is unknown.To investigate the mechanism of SLT would improve the therapeutic effect of SLT.The aqueous outflow resistance in trabecular meshwork was affected by the extracellular matrix (ECM). Matrix metalloproteinase-3(MMP-3) and MMP-9 were closely related to ECM degradation in trabecular meshwork.

This study was to observe the effects of SLT on the expressions MMP-3 and -9 in human trabecular cells in vitro.

Immortallized human trabecular cells were cultured with pigment particles mixed suspension for 16 hours and incubated overnight.Then the cells were irradiated with Q switch frequency doubling 532 nm Nd: YAG laser to establish SLT-effective cells with the energy of 0.2 mJ, spot diameter of 400 μm and pulse duration of 3 ns.The expressions of MMP-3 mRNA and MMP-9 mRNA in the cells were detected by fluorescence quantitative real time PCR before and 1 hour and 4, 8, 12, 28 hours after exposure of laser.The concentrations of MMP-3 and MMP-9 in the medium were assayed using ELISA 1 hour and 4, 8, 12, 28 hours after exposure of laser and compared between the non-irradiation group and the irradiation group.

The relative expressing levels of MMP-3 mRNA were 1.00, 1.32±0.12, 2.08±0.05, 2.34±0.04, 2.77±0.05 and 2.49±0.27 in the non-irradiation group and irradiation for 1 hour and 4, 8, 12, 28 hours after exposure of laser SLT, showing a significant difference among the groups (F=15.966, P=0.007), and relative expressing levels of MMP-3 mRNA were significantly higher in various time points after laser irradiation than those of the non-irradiation group (all at P<0.05). The relative expressing levels of MMP-9 mRNA were 1.00, 0.91±0.10, 1.27±0.07, 1.46±0.07, 1.69±0.09 and 0.87±0.09 in the non-irradiation group and irradiation for 1 hour and 4, 8, 12, 28 hours after exposure of SLT, which was considerably different among the groups(F=30.526, P=0.005), and significant increased values were seen in the 4, 8 and 12 hours after irradiation compared with the non-irradiation group (all at P<0.05), with highest expression in the irradiation for 12-hour group.The concentrations of MMP-3 and MMP-9 proteins in medium were significantly increased in various time points after laser exposure in comparison with the control group (all at P<0.05).

The expressions of MMP-3 and MMP-9 in human trabercuolar cells upregulate and the secretion ability of human trabecular cells to MMP-3 and MMP-9 proteins improves in early stage of SLT in vitro.However, these procedures gradually diminish with the lapse of time.

Argon; Laser therapy; Matrix metalloproteinases; Trabecular meshwork cell, human; Real-time PCR; ELISA