Abstract
Purpose:
To identify TGF-β2-induced proinflammatory cytokines secreted from trabecular meshwork cells.
Methods:
Cultured human trabecular meshwork cells were treated with vehicle (control), 1.0, 2.5, or 5.0 ng/ml human recombinant TGF-β2 for 24 hours after over-night serum starvation, and conditioned media were collected. Levels of interleukin (IL)-1α, IL-1β, IL-6, IL-8, IL-10, monocyte chemotactic protein (MCP)-1, tumor necrosis factor (TNF)-α, platelet-derived growth factor (PDGF)-AA, PDGF-AB/BB, and vascular endothelial growth factor (VEGF) were simultaneously determined by multiplex immunoassay. Each experiment was conducted in triplicate. The data were analyzed using the Dunnett’s multiple comparison test.
Results:
IL-1α, IL-1β, TNF-α and VEGF were undetectable in any of the conditioned media. The mean levels (±SD) of IL-6, IL-8, IL-10, MCP-1, PDGF-AA and PDGF-AB/BB in the control condition were 6.8 ± 0.2, 3.0 ± 0.6, 1.8 ± 0.1, 19.3 ± 0.6, 1.2 ± 0.1 and 1.0 ± 0.2 pg/ml, respectively. After stimulation with TGF-β2, the levels of IL-6, IL-8 and PDGF-AA were significantly increased (P <0.001 for each) compared with control, while the levels of IL-10, MCP-1, PDGF-AB/BB were not different among conditions. The IL-6 levels were significantly increased by 4.2, 4.3 and 4.6 times after stimulation with 1.0, 2.5 and 5.0 ng/ml TGF-β2, respectively compared with control. The corresponding values for IL-8 were 1.9, 2.1 and 2.4. For PDGF-AA, those values were 5.9, 17.6 and 30.5, and the increase was dose-dependent (P <0.001).
Conclusions:
TGF-β2 induced IL-6, IL-8 and PDGF-AA secretions from trabecular meshwork cells, suggesting that TGF-β2 may induce secondary proinflammatory responses in aqueous outflow tissues and thereby modulate glaucoma pathology.
Keywords: 735 trabecular meshwork •
490 cytokines/chemokines •
543 growth factors/growth factor receptors