Role of TGF-β in tissue eosinophilia associated with vernal keratoconjunctivitis

To determine the role of TGF-β1 in the tissue eosinophilia associated with vernal keratoconjunctivitis (VKC), we investigated the immunohistochemical expression of TGF-β1 and TGF-β1-related proteins in giant papillae obtained from VKC patients. We also investigated the effect of TGF-β1 on production of eotaxin by cultured conjunctival and corneal fibroblasts using ELISA. Finally, the effects of glucocorticoids, cyclosporine, and tacrolimus on eotaxin production by corneal fibroblasts were assessed. Our investigations revealed that eosinophils expressing TGF-β1 and TGF-β1-related proteins (such as phosphorylated Smad2, integrin αvβ6, α-smooth muscle actin, type I procollagen, and tenascin-C) were expressed in the giant papillae. TGF-β1 and IL-4/IL-13 caused a synergistic increase of eotaxin production in cultured conjunctival and corneal fibroblasts. This effect of TGF-β1 and IL-4/IL-13 was inhibited by glucocorticoids, but neither by cyclosporine nor by tacrolimus. In conclusion, TGF-β1 has an important role in the tissue eosinophilia associated with VKC.

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► TGF-β1-positive eosinophils are detected in giant papillae of VKC patients.
► TGF-β1 and IL-4/IL-13 synergistically increase eotaxin production by fibroblasts.
► Eotaxin production from corneal fibroblasts is inhibited by steroid.
► TGF-β1 has a crucial role in the tissue eosinophilia associated with VKC.