Abstract
Purpose: :
Despite the lack of overt signs of inflammation the IL-1 cytokine has been observed to be constitutively up regulated in human glaucomatous trabecular meshwork (TM) compared to control tissues. This acute up regulation has been shown to increase aqueous outflow in vivo and to protect the TM tissue against oxidative stress inducing agents in vitro. We hypothesize that the acute beneficial role of IL-1 induction may become deleterious when expressed on a prolonged basis and may play a role in the pathogenesis of primary open angle glaucoma (POAG).
Methods: :
Porcine TM primary cultures were treated with IL-1 alpha or beta in media with or without 10% fetal bovine serum (FBS) added. Responsorial changes in cell permeability, cell adhesion and cytoskeletal organization were assayed. Cells were also exposed to oxidative stress inducing agents and changes in cell viability determined using the MTT assay. Each experiment examined changes over several different time points.
Results: :
Reorganization of the cytoskeleton, visualized by phalloidin staining, was observed after 24 hours in the IL-1 treated group compared to the no treatment groups in the absence of FBS in the media. A statistically significant difference (p-value < 0.05) was observed in the induced culture compared to the no treatment group in the in vitro permeability assay; the addition of FBS to the culture media did not alter the results obtained with IL-1 induction. However, the addition of FBS did affect the results obtained on cell adhesion and cell viability after exposure to oxidative stress inducing agents. IL-1 plus FBS treated cells showed increased adhesion and cell viability, whereas IL-1 in FBS minus media showed a decrease in both assays compared to no IL-1 treated controls (p-value < 0.05).
Conclusions: :
The assays selected examined the cellular properties that could alter the resistance to aqueous outflow in the TM tissue, one of the determinants of intraocular pressure. Our results reveal a dual effect of IL-1 on TM cells depending on the culture media conditions, offering a mechanism by which the cytokine could exert both a beneficial role and also participate in disease pathogenesis, depending on the extracellular environmental conditions.
Keywords: outflow: trabecular meshwork • cell survival • cell adhesions/cell junctions