Abstract
Purpose:
To characterize the effects of two in vitro models of dry eye on the expression/mobilization of HLA-DR known as a biomarker of dry eye. We investigated the effect of hyperosmolarity (HO) and desiccation stress (DS) on the membrane expression and the induction of HLA-DR mRNA as a first step to inflammation in dry eye disease in correlation with other inflammatory biomarkers such as IL-6, IL-8.
Methods:
Hyperosmolar (HO) and desiccative stresses (DS) were induced on conjunctival cells (Wong-Kilbourne-derived of Chang Conjunctiva, WKD). WKD were exposed either to NaCl-induced HO conditions (500mOsm) for 24h or to desiccating conditions by seeding them on transwell membranes (d: 2.4cm, pore 0.4 μm) and incubated in a drying chamber (relative humidity: 17±3%) for 6h after cell culture medium removal from the upper side of the transwell. We evaluated the effect of HO or DS on IL-6, IL-8 and HLA-DR mRNA expression by qRT-PCR. IL-6 and IL-8 were measured for each stress condition using ELISA assay. HLA-DR cell was investigated using flow cytometry and immunofluorescence analyses.
Results:
Both HO and DS induced an increase of IL-6 and IL-8 mRNA in WKD cells and a production of IL-6 and IL-8 in the supernatant. HO and DS induced a mild increase of the HLA-DR mRNA synthesis and a translocation of the cytoplasmic HLA-DR to the cell membrane confirmed by flow cytometry when compared to basal conditions.
Conclusions:
By using these two in vitro dry eye models, we confirmed the proinflammatory profile induced by hyperosmolar or desiccating conditions on conjunctival cells. These conditions could trigger HLA-DR translocation at the cell membrane without the presence of IFNγ released by immune cell infiltration. These observations revealed the existence of a preliminary step in the chronic dry eye inflammation process.
Keywords: 474 conjunctiva •
557 inflammation •
726 stress response