Pathological changes of meibomian gland and ocular surface in Apolipoprotein E knockout mice

Abstract

Purpose : To investigate the pathological changes of meibomian gland (MG) and ocular surface tissues in Apolipoprotein E knockout (ApoE^-/-) mice, and to illustrate the effect of ApoE on meibomian gland function.

Methods : The ocular surface of ApoE^-/- male mice (n=30) aged from 3 months to 7 months, and age and sex matched wild type mice (n=30) was observed under slit lamp microscope. MG tissue sections underwent H&E staining, Oil Red O staining, TUNEL assay, and immuno-fluorescence staining for K10, Fabp5, Ki67, K6a, p63, PPAR-gamma, NF-kB p65, p-NF-kB p65, caspase 3, caspase 8, and immune-histochemical staining for CD45. Real-time RT-PCR and Western blot was performed to detect above mentioned gene expression in MG tissues. Lipid metabolism related genes expression in MG were also detected by real-time RT-PCR.

Results : Eyelid thickening, keratinization and corneal neovascularization occurred in ApoE^-/- mice at the age of 5 months, and the changes were more obvious at 7 months. H&E staining showed hypertrophy of the meibomian gland acinus, and Oil red O staining showed accumulation of lipid in MG acinus of ApoE^-/- mice. Both K10 and Fabp5 expression were increased, while Ki67, K6a, p63 were decreased in ApoE^-/- mice compared to the wild type mice. Cytoplasmic and nuclear expression of PPAR-gamma was decreased, NF-kB p65, p-NF-kB p65, caspase 3, and caspase 8 expression were higher in the ApoE^-/- mice compared to the wild type mice. TUNEL assay showed more positive cells in the meibomian gland acinus of ApoE^-/- mice. CD45 positive cell infiltration increased from 5 months to 7 months in ApoE^-/- mice. Lipid metabolism related genes such as FFAR1, PAR3, ACSL3, and LIPC were decreased in ApoE^-/- mice compared to the wild type mice.

Conclusions : ApoE knockout mice represented abnormal meibomian gland acinar cell proliferation, differentiation, and lipid metabolism, they also showed eyelid and corneal pathological changes. These mice may be used as model to study the pathophysiology of meibomian gland dysfunction.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.