Variation in the Expression of Inflammatory Markers and Neuroreceptors in Human Conjunctival Epithelial Cells

The purpose of this research was to investigate the role of neurogenic involvement in the etiopathogenesis of ocular surface inflammation, with the final goal of identifying new potential anti-inflammatory agents. We describe the presence of two “classic” markers of inflammation (HLA-DR and ICAM-1) and some neuroreceptors in cultured human conjunctival epithelial cells under basal and pro-inflammatory conditions. Two markers of inflammation (HLA-DR, ICAM-1) and several neuroreceptor subtypes (M1-, M2-, and M3-muscarinic; α1A-, α1B-, α1D-, α2A-, α2B-, α2C-, β1-, β2-, and β3-adrenergic) were analyzed in a normal human conjunctival epithelial cell line (IOBA-NHC). These markers were studied in basal conditions and under the influence of two pro-inflammatory cytokines: tumor necrosis factor alpha (TNF-α) and/or interferon gamma (IFN-γ). Immuno-fluorescence (confocal microscopy), western blotting, or flow cytometry techniques were used. In basal conditions, epithelial cells expressed all inflammatory markers except HLA-DR. The addition of IFN-γ enhanced expression of HLA-DR, ICAM-1, and M2-muscarinic receptor. TNF-α up-regulated the expression of ICAM-1. When epithelial cells were incubated in the presence of both cytokines together, the cell surface expression of HLA-DR, ICAM-1, α1B-, and α2B-adrenergic receptors was increased. Cultured human conjunctival epithelial cells have been shown to be susceptible to up-regulation of the expression of inflammatory markers and cell membrane expression of some neuroreceptors under pro-inflammatory conditions. Consequently, pharmacologic neuromodulation could have a role in the comprehensive management of ocular surface inflammation.