Abstract
Purpose: :
A significant risk factor for the development of meibomian gland dysfunction (MGD) is exposure to isotretinoin. This compound, which originates from vitamin A, is frequently used to treat severe acne, because it significantly decreases the generation and function of sebaceous gland epithelial cells. However, the mechanism(s) underlying isotretinoin-induced MGD is unknown. We hypothesize that isotretinoin reduces the proliferation and differentiation of MG epithelial cells. This study’s purpose was to test our hypothesis.
Methods: :
Immortalized human meibomian gland (SLHMG) and conjunctival (gift from Dr. Ilene Gipson) epithelial cells were cultured in basal, proliferating (i.e. stimulation with epidermal growth factor and bovine pituitary extract) or differentiating (i.e. stimulation with FBS) conditions for 5 to 10 days in the presence or absence of varying doses of isotretinoin (0.1, 1, 2, 5, 10 uM). Cells were counted with a hemocytometer, evaluated under phase contrast microscopy and/or stained with LipidTox neutral lipid stain and DAPI.
Results: :
Our results demonstrate that isotretinoin causes a significant time- and dose-dependent effect on the morphology and proliferation of SLHMG cells. Within 1 day of exposure to 5 or 10 µM isotretinoin, cells appeared to atrophy, lose vesicles and decline in number. After 6 days of treatment with these dosages, all cells had died. Administration of 1 to 2 µM isotretinoin led to a 33 to 83% decrease in cell proliferation during a 5-7 day time period, whereas an 0.1 µM dose had no effect on cell number. Treatment of conjunctival epithelial cells with 1 µM isotretinoin had no impact on their proliferation. Exposure of SLHMG cells to 1µM isotretinoin did not appear to alter the FBS-induced accumulation of neutral lipid. However, such a concentration seemed to increase the LipidTox staining of cells cultured in basal media.
Conclusions: :
Our findings show that 1 µM isotretinoin reduces the proliferation, but not the apparent differentiation, of SLHMG cells. Our results also demonstrate that 5 and 10 µM doses of isotretinoin are toxic to these cells. Whether isotretinoin alters the nature of the lipid composition within SLHMG cells remains to be determined.
Keywords: differentiation • lipids • proliferation