The effect of denatured lysozyme on human corneal epithelial cells

TitleThe effect of denatured lysozyme on human corneal epithelial cells
Publication TypeJournal Article
Year of Publication2018
AuthorsMcCanna, D., S. Oh, J. Seo, C. Coles-Brennan, Z. Fadli, L. Subbaraman, and L. W. Jones
JournalInvestigative Ophthalmology and Visual Science
Keywordsannexin, apoptosis, Article, Calcein, cell immortalization, cell line, cell membrane, cell survival, cell viability, chemistry, Confocal, confocal microscopy, controlled study, cornea cell, cornea epithelium, Corneal, cytokine, cytokine release, Cytokines, drug effect, enzyme activity, enzyme binding, Epithelium, epithelium cell, gamma interferon, human, human cell, Human corneal epithelial cells, Humans, inflammatory cell, interleukin 10, interleukin 12, interleukin 1beta, interleukin 4, interleukin 6, interleukin 8, lens, lysozyme, Metabolic activity, metabolic activity assay, metabolism, Micrococcus luteus, Microscopy, Muramidase, priority journal, protein denaturation, protein refolding, tumor necrosis factor

PURPOSE. During contact lens wear, the amount of lysozyme deposited on contact lenses varies depending on the lens material. The binding of lysozyme to some contact lens materials may result in a conformational change that denatures the protein to an inactive form. This investigation evaluated the effect that denatured lysozyme has on human corneal epithelial cells (HCECs) by measuring cell viability and the release of inflammatory cytokines. METHODS. HCECs were exposed to lysozyme that was denatured to various activity levels. After 24-hour exposure to the lysozyme (1.9 mg/mL) in growth media, the cells were evaluated for cell viability using confocal microscopy. The metabolic activity of the cells was determined using an alamarBlue assay. Cell supernatants were analyzed for inflammatory cytokines. RESULTS. Using confocal microscopy, there was no detectable change in the viability of the HCECs after exposure to the denatured lysozyme. However, using alamarBlue, a decrease in the metabolic activity of the HCECs exposed to denatured lysozyme was detected. HCECs exposed to lysozyme that was 67%, 47%, and 22% active showed a reduction in metabolic activity when compared with native (100% active) lysozyme and the media controls (P < 0.05). Exposure to the denatured lysozyme also caused an increase in the release of inflammatory cytokines (P < 0.05) from the HCECs. CONCLUSIONS. The results of this study show that denatured lysozyme can have a detrimental effect on HCECs. Both a reduction in metabolic activity and an increase in the release of inflammatory cytokines occurred after HCEC exposure to denatured lysozyme. © 2018 The Authors.