Differential and cooperative effects of TNFalpha, IL-1beta, and IFNgamma 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 TNFalpha, IL-1beta, and IFNgamma 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: TNFalpha, IL-1beta, and IFNgamma had distinctive individual and combined effects on the parameters tested. Although TNFalpha and IL-1beta had similar and synergistic effects on increasing expression of ICAM-1, IL-1beta was a more potent upregulator of the release of IL-8 than was TNFalpha. Upregulation of IL-8 was additive when IL-1beta was combined with TNFalpha. Neither TNFalpha nor IL-1beta increased expression of HLA. In contrast, IFNgamma was a potent upregulator of both surface receptors (ICAM-1 and HLA) but IFNgamma alone had no effect on mediator release (IL-8 and RANTES). Release of RANTES required two cytokine signals, with IFNgamma and TNFalpha 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.