Cellular sensitivity to glucocorticoids in patients with POAG

The question of a generalized hypersensitivity to corticosteroids in primary open-angle glaucoma (POAG) was investigated using cultured skin fibroblasts from patients with POAG and age-matched controls. Nuclear binding of (³H)-dexamethasone was performed to evaluate possible changes in the glucocorticoid receptors. Cortisol effects on (³H)-thymidine uptake into the cells were investigated as a measure of the cellular sensitivity to corticosteroids. When POAG and control groups were compared, no significant differences (P<0.05) were found for either the number of affinity of glucocorticoid receptors (POAG: K(d) = 6.1 ± 1.0 nM, R(t) = 94 ± 13 sites/cell x 10³; control: K(d) = 5.5 ± 1.6 nM, R(t) = 124 ± 20 x 10³ sites/cell) or for cortisol effects on thymidine uptake (POAG: C₅₀ = 83 ± 38 nM; control: C₅₀ = 80 ± 34 nM). Use of epidermal growth factor (EGF) resulted in an increased steroid sensitivity in some cell lines, but again no differences between POAG and control groups were detected. These results suggest that a generalized cellular hypersensitivity to glucocorticoids is not intrinsic to POAG. It is possible that environmental alterations and/or endogenous factors may influence the steroid responses observed in these patients.