Abstract
Purpose :
Meibomian gland is a holocrine gland which secrets lipid to the ocular surface. Its dysfunction known as meibomian gland dysfunction is one of the most common cause of dry eye syndrome especially among elderly. In the basal layer of this gland, epithelial cells are continuously proliferating. Then the cells differentiate, accumulate lipid, and finally undergo cell death. The contents of cells are released as meibum. Thus, continuous cell proliferation in the basal layer and following differentiation of proliferated cells is essential for excreting function in holocrine glands. Sodium butyrate (NaB), a histone deacetylase inhibitor, has been reported to induce differentiation and cell cycle arrest in various cells including glandular epithelial cells and adipocytes. Therefore, we hypothesized that NaB stimulated differentiation of meibomian gland epithelial cells.
Methods :
Immortalized human meibomean gland epithelial cells kindly provided from Dr. D. Sullivan were cultured in proliferation medium. Sub-confluent cultures were then incubated with differentiation medium containing 1 - 10 mM NaB. Cell viability, DNA synthesis and cell death were evaluated by MTS methods, immunocytochemistry for BrdU, and assay of lactate dehydrogenase activities released from dead cells into culture supernatant, respectively. Acetylasion of histone was evaluated immunocytochemically using anti-acetyl histone H3 antibody. Intracellular lipid vesicles were visualized by BODIPY 493/503 dye and tight junction protein ZO-1 was detected by immunocytochemical staining.
Results :
NaB dose-dependently inhibited cell proliferation and increased cell death, and promoted lipid accumulation and localization of ZO-1 along cell boundary. NaB increased number of acetylated histone-positive nuclei and enhanced their intensity of staining.
Conclusions :
In immortalized human meibomian gland epithelial cells, NaB induces suppression of cell proliferation, promotion of differentiation and increased intracellular ipid storage followed by cell death.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.