Interleukin-1beta-induced disruption of barrier function in cultured human corneal epithelial cells

Abstract

Purpose: The barrier function of the corneal epithelium contributes to corneal homeostasis and is impaired by inflammation. Adherens junctions (AJs) and tight junctions (TJs) of the corneal epithelium are essential for cell adhesion and barrier function. We examined the effects of the proinflammatory cytokine interleukin (IL)-1beta on AJs and TJs as well as on barrier function in simian virus 40-transformed human corneal epithelial (HCE) cells.

Methods: Barrier function was evaluated by measurement of transepithelial electrical resistance (TER). The subcellular distributions of the AJ proteins E-cadherin and beta-catenin, the TJ proteins ZO-1 and occludin, and the p65 subunit of nuclear factor (NF)-kappaB were determined by immunofluorescence staining. The expression of junctional proteins as well as the phosphorylation and degradation of the NF-kappaB-inhibitory protein IkappaB-alpha were examined by immunoblot analysis.

Results: IL-1beta induced the disappearance of ZO-1 and occludin from the interfaces of neighboring HCE cells without affecting the localization of E-cadherin or beta-catenin. It also reduced the TER of HCE cells in a concentration- and time-dependent manner. The overall abundance of TJ and AJ proteins was not affected by IL-1beta. IL-1beta induced the phosphorylation and downregulation of IkappaB-alpha as well as the translocation of p65 to the nucleus. The NF-kappaB inhibitor curcumin blocked the effects of IL-1beta on both TER and the subcellular localization of ZO-1 and occludin.

Conclusions: IL-1beta induced the redistribution of ZO-1 and occludin from TJs of HCE cells and thereby disrupted the barrier function of these cells in a manner dependent on NF-kappaB. These effects of IL-1beta may contribute to the loss of corneal epithelial barrier function associated with ocular inflammation.