Abstract
Purpose::
TGFß2 is a pleitrophic factor regulating many cellular processes including cell growth and differentiation, cell adhesion, immune response, and wound healing. TGFß2 is elevated in aqueous humor of many patients with primary open angle glaucoma and has been shown to increase outflow resistance when perfused into the anterior segment of human eyes. To identify genes in the trabecular meshwork (TM) that are differentially regulated by TGFß2, we performed microarray experiments on TM isolated from anterior segments following perfusion of TGFß2.
Methods::
Anterior segments of human eyes (n=17 pairs) were placed in organ culture and perfused with either DMEM (Dulbecco’s Modified Eagle’s Media) containing 50% porcine aqueous humor and TGFß2 (3 ng/ml) or DMEM containing 50% porcine aqueous humor and vehicle (4 mM HCl). One eye received an anterior exchange followed by continuous perfusion with DMEM containing 50% porcine aqueous humor and TGFß2 while the fellow eye received an equal volume of DMEM containing 50% porcine aqueous humor and vehicle. Following 8 hour or 96 hour incubation, TM were dissected and placed in Trizol reagent. Total RNA was isolated from individual TM and 100 ng was amplified twice and processed into cRNA. Affymetrix GeneChip Human Genome U133 Plus 2.0 arrays were probed with cRNA. Microarray data was analyzed using Genespring and Genego Analysis Programs (Metacore).
Results::
TGFß2 increased outflow resistance at 8 hours by 44% ± 27% (mean ± SD) in human anterior segments while the fellow control eye increased outflow resistance by 8% ± 19% (n=11, p=0.001). Anterior segments maintained the increase in outflow resistance at 96 hours (43% ± 27%) when compared to the fellow control eye (-15% ± 20%; n=6, p=0.013). At 8 hours, genes associated with integrin-mediated signaling (i.e. integrin beta 1, etc), cell and focal adhesions, and molecules involved in actin cytoskeleton remodeling were differentially expressed. Expression of molecules associated with inflammation were also altered throughout the incubation period.
Conclusions::
TGFß2 increases outflow resistance in human anterior segments. Identification of genes associated with cell-cell and cell-matrix interactions indicate changes in cell and focal adhesion may play a role in TGFß2 induced outflow resistance. Further molecular based studies are necessary to determine whether a correlation exists between elevated levels of TGFß2, changes in gene expression, and increased outflow resistance.
Keywords: trabecular meshwork • aqueous • gene/expression