Differential and Cooperative Effects of TNFα, IL-1β, and IFNγ on Human Conjunctival Epithelial Cell Receptor Expression and Chemokine Release

Abstract
Purpose. To gain better understanding of conjunctival epithelial cell responses to proinflammatory cytokines, the individual and combined effects of TNFα, IL-1β, and IFNγ on chemokine release (IL-8, regulated on activation normal T-cell expressed and secreted [RANTES]) and surface receptor expression (intercellular adhesion molecule [ICAM]-1, and HLA-DR, -DP, and -DQ) were examined. methods. Conjunctival epithelial cells were isolated from cadaveric conjunctival tissues and cultured in 24-well plates until almost confluent. Recombinant cytokines (0.005–50 ng/mL) were added, alone or in various combinations, 24 hours before harvesting of supernates for ELISAs and cells for flow cytometry. results. TNFα, IL-1β, and IFNγ had distinctive individual and combined effects on the parameters tested. Although TNFα and IL-1β had similar and synergistic effects on increasing expression of ICAM-1, IL-1β was a more potent upregulator of the release of IL-8 than was TNFα. Upregulation of IL-8 was additive when IL-1β was combined with TNFα. Neither TNFα nor IL-1β increased expression of HLA. In contrast, IFNγ was a potent upregulator of both surface receptors (ICAM-1 and HLA) but IFNγ alone had no effect on mediator release (IL-8 and RANTES). Release of RANTES required two cytokine signals, with IFNγ and TNFα being the most potent combination. conclusions. Knowledge of the differential and combined effects of proinflammatory cytokines on conjunctival epithelial cells allows better understanding of ocular inflammation.