Browsing by Subject "Epithelium, Corneal"
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Item Effect of ULK1 Inhibition on Corneal Epithelial Cells During Pseudomonas aeruginosa Infection(2024-01-30) Abdallah, Joelle; Ayilam Ramachandran, Rajalakshmy; Robertson, Danielle M.INTRODUCTION: Pseudomonas aeruginosa (PA) keratitis is a severe infection of the cornea that can lead to blindness. Studies in our lab have shown that PA exploits autophagy, a major cellular degradation process, in corneal epithelial cells (hTCEpi cells) to promote intracellular survival. We have further shown that the inhibition of autophagy by the Unc 51-like kinase (Ulk1), an enzyme that mediates formation of the autophagosome, reduces intracellular levels of PA. More recently, we have demonstrated that PA infection negatively impacts host mitochondria. ULK1/2 has been reported to translocate to mitochondria to mediate mitophagy however, a role for ULK1/2 in mitochondrial homeostasis during infection has not yet been explored. In this study, we investigated the effects of the inhibition of Ulk1 during PA infection on host mitochondria. METHODS: Telomerase-immortalized human corneal epithelial (hTCEpi) cells were used for this study. Cells were cultured in serum-free defined keratinocyte media with growth supplements. Cells were inoculated with 106 CFU/ml of PA in log growth phase with or without treatment with 1 ï�M of the Ulk1/2 inhibitor MRT68921. Intracellular levels of PA were quantified using a gentamicin survival assay. Oxygen consumption and mitochondrial polarization were assessed using Seahorse metabolic flux analysis and tetraethyl-benzimidazolyl-carbocyanine iodide (JC-1), respectively. Levels of pro-inflammatory cytokines were assessed using ELISA. Untargeted metabolomics was performed using mass spectrometry. Cellular changes were further evaluated using transmission electron microscopy (TEM). RESULTS: PA infection induced robust mitochondrial depolarization. There was a corresponding increase in secretion of IL-6 and IL-8. Treatment with MRT68921 restored mitochondrial polarization and reduced IL-6, but had no effect on IL-8. MRT68921 also reduced intracellular levels of PA. TEM demonstrated robust mitochondrial fission during PA infection. Treatment with MRT68921 preserved mitochondrial structure and polarization during PA infection. CONCLUSIONS: Taken together, these data suggest that Ulk1/2 modulates the host mitochondrial response to PA infection. Further studies are needed to determine the mechanism by which MRT68921 preserves mitochondrial function and its potential use as an adjunct therapeutic for PA-mediated keratitis.Item Reconstitution of a Multi-layered, Differentiated Cornea by HTERT-Immortalized Corneal Epithelial Cells Transduced with Thymidine Kinase Transplanted onto Denuded Mouse Corneas(2011-10-25) Kalangara, Jerry P.; Cavanagh, H. DwightOBJECTIVE: To develop an animal model for the implementation of human telomerase enzyme reverse transcriptase (hTERT)-immortalized human corneal epithelial cell line (hTCEpi) transduced with the hygromycin-thymidine kinase gene (HyTK) as a viable cell source for the reconstruction of the corneal surface. METHODS: HyTK cells were cultured in KGM-2 serum-free culture media under hygromycin B selection. Limbal stem cell deficiency (LSCD) was established in athymic nude mice (n=75) using ethylenediaminetetraacetic acid (EDTA) and mitomycin C treatment followed by mechanical debridement of corneal and limbal epithelium. Immunofluorescence (IF) using Anti-Laminin and Propidium iodide (PI) was used to assess presence of basement membrane after epithelial removal. Cultured HyTK cells were stained with Cell Tracker Green CMFDA (5-chloromethylfluorescein diacetate) and transplanted onto the right eye after epithelial removal; the left eye served as a control. Transplanted cells were evaluated at 4 hours, 1 day, and 7 days post-transplantation using laser scanning confocal microscopy (LSCM). At 4 hours and 1 day, corneas were imaged for the presence of CMFDA. At day 7, corneas were stained using antibodies to Keratin 3, Ki-67, and the fluorescent probes – PI, and Phalloidin. Cytotoxicity of ganciclovir was assessed at concentrations of 0.1, 0.5, 1.0, 5.0, and 10.0 μM using Live-Dead Assay. RESULTS: IF confirmed an intact corneal basement membrane following epithelial removal. At 4 hours and 1 day post-transplantation, CMFDA staining demonstrated that transplanted cells were dispersed throughout the corneal surface. After 7 days, HyTK cells showed stratification and IF confirmed a differentiated corneal epithelial phenotype. Incubation in ganciclovir induced a cytotoxic effect on HyTK cells in vitro and had no significant effect on the hTCEpi control cell line. This effect was significant at 0.5 µM (p < 0.05). CONCLUSIONS: These studies demonstrate the first reconstitution of a multi-layered, differentiated corneal epithelium by HyTK cells in the nude mouse model; further, proliferating HyTK cells can be killed with ganciclovir treatment in vitro, which may reduce the potential for risk of oncogenic transformation in vivo.