Abstract
Abstract: :
Purpose: The cornea is always affected by various physical factors, such as, temperature, humidity, ultraviolet irradiation, and airflow. Cellular viability of the ocular surface is significantly affected by dryness. We studied the influence of dryness on corneal cells using human corneal epithelial cell line (CEPI) and dry eye model rats. Methods: CEPI was grown in keratinocyte growth medium 2 (KGM2), which was a serum–free medium with the addition of bovine pituitary extract, to approximately 80% confluence in 96–well plates or <font face="symbol">Æ</font> 6 cm2 dishes. The medium was discarded by aspiration and plates were left for 0, 5, 10, 15, 20, 25, and 30 minutes with the cover open to dry the cells. KGM2 containing 10% alamar Blue was poured into the plates to estimate the viability of the cells. CEPI in <font face="symbol">Æ</font> 6 cm2 dishes were dried by the same method as above, and KGM2 was poured into the dishes. Fifteen minutes later, the medium was collected to measure the concentration of the cytokines in medium by EIA. The expression of cytokines in the corneas of dry eye model rats was measured by real time PCR Results: CEPI lived for about 20 minutes under the drys conditions. IL–6 and TNF–α were always detected in the medium, but interferon γ was not detected. The mRNA of interferon γ was not detected in CEPI by RT–PCR. The secretion volume of IL–6 increased significantly after 10 minutes of dryness, but that of TNF–α did not change. The mRNA of IL–6 obtained from the cornea in dry eye model rats also increased significantly, but the mRNA of TNF–α did not change. Conclusions:Cell death due to dryness is suggested to be related to IL–6 secretion but not TNF–α secretion.
Keywords: cell death/apoptosis • cornea: basic science • cornea: epithelium