Abstract
Purpose:
Clinical features of severe ocular allergic disease, vernal keratoconjunctivitis, are the severe conjunctival inflammation and the corneal epithelial damage due to eosinophils which results in visual disturbance. Corneal stromal fibroblasts are the main source of CCL11/eotaxin-1. To know the role of alarmins from damaged corneal epithelial cells in tissue eosinophilia, we have now examined the effects of the supernatant derived from necrotic corneal epithelial cell and Th2 cytokines on corneal fibroblasts.
Methods:
Necrosis of cultured human corneal epithelial cells was induced by repeated freezing and thawing. The amount of chemokines released into culture medium by human corneal fibroblasts was determined by enzyme-linked immunosorbent assay, surface expression of adhesion molecules on the cultured cells was measured with a whole-cell enzyme-linked immunosorbent assay, and the intracellular abundance of these molecules mRNA was quantitated by reverse transcription and real-time polymerase chain reaction analysis. Signaling by the transcription factors NF-κB was evaluated by immunoblot and immunofluorescence analyses.
Results:
The supernatant from necrotic corneal epithelial cells induced a low level of CCL11 release by corneal fibroblasts, as did Th2 cytokines, IL-4 and IL-13. However, the combination of the supernatant from necrotic corneal epithelial cells and IL-4 or IL-13 induced a marked synergistic increase in CCL11 release. The abundance of CCL11 mRNA in the fibroblasts was also increased in a synergistic manner by costimulation with the supernatant from necrotic corneal epithelial cells and IL-4 or IL-13. In addition, the combination of the supernatant from necrotic corneal epithelial cells and IL-4 or IL-13 synergistically increased the expression of VCAM-1 in corneal fibroblasts. The supernatant from necrotic corneal epithelial cells activated NF-κB in corneal fibroblasts, and inhibitors of NF-κB and IL-1 receptor antagonist attenuated CCL11 release and VCAM-1 expression induced by the supernatant from necrotic corneal epithelial cells in combination with IL-4 or IL-13.
Conclusions:
The interaction between IL-1 from necrotic corneal epithelial cells and Th2 cytokines may play an important role in tissue eosinophilia associated with ocular allergic diseases.
Keywords: 480 cornea: basic science •
484 cornea: stroma and keratocytes •
490 cytokines/chemokines