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Alexander Steven Barsam, Ying Wang, Andres Reyes-Capo, Maitee Urbieta, Hunter Mitchell, Tongyu Cao Wikramanayake, Victor L Perez; Functional consequences of Mpzl3 knockout in the ocular surface of mice . Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4035.
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© ARVO (1962-2015); The Authors (2016-present)
In the skin, the Mpzl3 (Myelin-Protein Zero-like 3) cell adhesion molecule is normally expressed in the epidermis, hair follicles, and sebaceous glands. Mpzl3 has a complex role in skin development; Mpzl3 knockout (-/-) mice developed sebaceous hypertrophy, hair loss, and inflammatory skin lesions, as well as a drastic reduction in adipose tissue. Additionally, Mpzl3 -/- mice developed eyelid abnormalities. However the role of Mpzl3 in the cornea and eyelid physiology is unknown. The purpose of our study is to determine (1) if Mpzl3 is expressed in the eye, specifically in the cornea and eyelid, and (2) if corneal and eyelid abnormalities develop in MPZL3 -/- mice.
Mpzl3 knockout mice were generated as described (Leiva et al., 2014), and loss of Mpzl3 RNA and protein expression was confirmed in -/- skin with RT-PCR analysis and immunofluorescent staining. Heterozygous knockout (+/-) mice showed no gross or histological abnormalities. A lacZ reporter gene was knocked in, so that its expression is driven by the endogenous Mpzl3 regulatory elements. Eyes with eyelids were harvested from Mpzl3 +/- (n=4, control) and -/- (n=5) mice, embedded in OCT, and sectioned for histological examination (H&E and β-Gal staining). Immunofluorescent staining (e.g. CD4, CD8, CD11-b, and CD19) was also performed to detect innate and adaptive immune system cells.
β-Gal staining revealed Mpzl3 promoter activity in the corneal epithelium and the hair follicles and epidermis of eyelids. Mpzl3 -/- mice exhibited swollen eyelids with dandruff-like flakes. H&E staining showed epidermal hyperplasia and increased inflammatory cell infiltration in the Mpzl3 -/- eyelids compared with +/- eyelids. Immunofluorescent staining confirmed that the vast majority of infiltrating cells corresponded to both innate and adaptive immune cells. Macrophages and CD4 T cells are particularly prominent in the eyelid, but not in the corneas of Mpzl3 -/- mice.
Our preliminary results detected Mpzl3 promoter activity in the epithelium of the cornea, hair follicles and epidermis of eyelids. Loss of Mpzl3 function resulted in an inflammatory eyelid phenotype, suggesting that Mpzl3 may be directly or indirectly involved in immune function. Further studies will attempt to characterize the immune system compartments of the Mpzl3 -/- mice.
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