Purchase this article with an account.
Yi-Chen Sun, Hau-Min Liou, Po-Ting Yeh, Fung-Rong Hu; Monocarboxylate Transporters Mediate the Fluorescein Uptake on Corneal Epithelial Cells. Invest. Ophthalmol. Vis. Sci. 2016;57(12):4901.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Fluorescein has been applied for the diagnosis of ocular surface disorders for over 100 years. The ability of fluorescein to diagnose was attributed to its tight-junctional permeability, and whether there is a separate mechanism for fluorescein transportation has not been determined. Monocarboxylate transporter (MCT) has been reported as a transporter shared by monocarboxylates and fluorescein in human intestinal Caco-2 cells. Interestingly, various fluorescein staining patterns are commonly observed between different ocular surface disorders, implying that fluorescein transportation could be mediated by a separate pathway. Investigation of how fluorescein is trafficked through corneal epithelial cells under different circumstances may therefore benefit further understanding of the pathogenesis of many ocular diseases.
Human corneal epithelial cells (HCECs) were cultured with addition of 1 mM fluorescein in the presence or absence of 4,4-diisothiocyanostilbene-2,2-disulfonate (DIDS), an MCT inhibitor. Separately, HCECs were cultured in medium with various pH values (6.2 to 7.4) under different treatment periods (5 to 15 min). In vivo, rabbit corneal surface was topically applied with 200 µl of fluorescein, with or without DIDS treatment. The intracellular levels of fluorescein were examined by using F-7000 Spectrophotometer for HCEC culture in vitro, as well as corneal impression cytology and external eye photographs for rabbit cornea in vivo, respectively.
Fluorescein uptake in HCECs was significantly decreased following treatment of MCT inhibitor DIDS in a time- and concentration-dependent manner. Meanwhile, reducing the pH values in culture medium also increased fluorescein uptake into HCECs. Because MCT has been reported as a proton-linked transporter, fluorescein uptake as a result of the increased level of proton implies MCT is indeed involved in fluorescein transportation. Consistent to the in vitro finding, intracellular fluorescein signal on rabbit cornea treated with DIDS was decreased following topical treatment of DIDS.
In this study, we found the penetration of fluorescein in corneal epithelial cells could be an active process mediated by MCT transporter family. Further study of the value of MCT-mediated transportation on HCECs may potentially benefit differential diagnosis and contribute better understandings of ocular surface disorders.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
This PDF is available to Subscribers Only