[show abstract][hide abstract] ABSTRACT: Major-histocompatibility-complex class I-related chain A (MICA) antigens are the ligands of NKG2D, which is an activating or coactivating receptor expressed on human NK cells and CD8+T cells. We sought to determine whether MICA expression in human corneal epithelium (HCE) could affect the cytotoxicity mediated by NK cells or CD8+T cells.
Cell cultures of HCE were harvested from human donor eyes. Flow cytometric analysis and ELISA was performed to determine the levels of MICA expression on HCE. Then, HCE was transfected with a lentivirus vector expressing MICA and GFP. Flow cytometric analysis, RT-PCR, western blot and ELISA were performed to check the levels of MICA expression. For cytotoxicity testing, allogeneic NK cells and CD8+T cells were isolated from peripheral blood mononuclear cells of healthy volunteers by magnetic cell sorting. The cytolytic activity of NK cells and CD8+T cells was assessed against MICA-transfected HCE (NK cells: E:T ratio = 3:1; CD8+T cells: E:T ratio = 10:1) using the nonradioactive cytotoxicity detection kit lactate deshydrogenase.
Surface expression of MICA on corneal epithelium was identified at a low level. A cell line of stable human MICA-transfected corneal epithelium was successfully established. Heightened expression of MICA on HCE was found to promote the cytotoxicity mediated by NK cells or CD8+T cells, which could be blocked by an anti-MICA antibody.
MICA molecules may contribute to cytotoxic responses mediated by activated immune effector cells in corneal epithelium immunity.
[show abstract][hide abstract] ABSTRACT: Natural killer (NK) cells are important in the ocular surface innate response against viral and bacterial infection. Major-histocompatibility-complex class I-related chain A (MICA) antigens are ligands of natural killer group 2D, an activating or coactivating receptor expressed on NK cells. Recent studies demonstrated that interferon-gamma (IFN-γ) could modulate MICA expression in tumor cells. However, little is known about MICA expression and regulation in human corneal epithelium. Our study assessed whether the proinflammatory cytokine, IFN-γ, affects MICA expression in human corneal epithelium. We identified low levels of surface MICA expression in corneal epithelium using flow cytometry. IFN-γ promoted surface MICA expression in corneal epithelium and increased soluble MICA levels in a dose-dependent manner. IFN-γ also enhanced NK cell-mediated cytotoxicity against the corneal epithelium. Anti-MICA antibodies could further block this process. In summary, we describe a novel IFN-γ function in the regulation of the innate response in ocular surfaces.
Journal of interferon & cytokine research: the official journal of the International Society for Interferon and Cytokine Research 03/2012; 32(3):115-20. · 1.63 Impact Factor
[show abstract][hide abstract] ABSTRACT: To study the morphology and the density of conjunctival goblet cells (GC) in patients with Sjögren's syndrome dry eye with in vivo laser scanning confocal microscopy (LSCM), and to explore its correlation with the GC density detected by impression cytology.
A total of 43 Sjögren's syndrome dry eye patients were recruited. All were required to fill in the Ocular Surface Disease Index Questionnaires. The tear break-up time was measured, followed by corneal fluorescein staining examination and Schirmer I test. The images of conjunctiva were taken by the Heidelberg retina tomography (HRT-II)/Rostock cornea module. Finally, the specimens for impression cytology were obtained. SPSS V.13.0 software was used to analyse the data.
Tear film function test showed that all patients had moderate to severe dry eye. The GC in LSCM images was characterised as a large hyper-reflective oval-shape cell with relatively homogeneous brightness. Though GC density assessed by LSCM (332 ± 137) cells/mm² was higher than that measured by impression cytology (200 ± 141) cells/mm², they showed a significant positive correlation, ρ = 0.908 (p < 0.05). Conclusion Conjunctival GC could be easily discriminated under the LSCM. LSCM may be a valuable tool in monitoring the progress and the follow-up of patients with Sjögren's syndrome dry eye.
The British journal of ophthalmology 12/2009; 94(11):1454-8. · 2.92 Impact Factor