Effects of transforming growth factor-β2 on myocilin expression and secretion in human primary cultured trabecular meshwork cells

High intraocular pressure (IOP) is a risk factor for primary open-angle glaucoma (POAG). The trabecular meshwork (TM), a reticular tissue in the outflow passage of the aqueous humor (AH), is a major contributor to intraocular outflow resistance. High levels of myocilin (MYOC), which is expressed in the TM, are associated with high IOP. Furthermore, transforming growth factor-beta 2 (TGF-beta 2) concentrations in human AH are significantly elevated in POAG patients. This study was designed to investigate the effects of TGF-beta 2 on MYOC expression and secretion in human primary cultured TM cells. Primary cultured human TM cells were treated with 0 (control group), 1, 10, and 100 ng/mL TGF-beta 2 for 12, 24, or 48 h. MYOC mRNA and protein expressions in TM cells and protein secretion in conditioned media were analyzed by semi-quantitative RT-PCR, Western blotting, and enzyme-linked immunosorbent assays (ELISA), respectively. TM cells treated with 1, 10, and, 100 ng/mL TGF-beta 2 for 48 h showed higher MYOC mRNA and protein expressions than those in the control group (0 ng/mL TGF-beta 2) (all P < 0.05). Treatment with TGF-beta 2 for 48 h also induced MYOC secretion in conditioned media in a dose-dependent manner (0 ng/mL: 7.107+/-1.163 pg/ml; 1 ng/mL: 7.879+/-1.894 pg/ml; 10 ng/mL: 8.063+/-1.181 pg/ml; 100 ng/mL: 8.902+/-0.699 pg/ml; all P < 0.05). In Conclusion, TGF-beta 2 induced MYOC expression and secretion in human primary cultured TM cells. Further investigations are required to confirm the involvement of these two factors in POAG pathogenesis.