Conjunctival expression of thymosin-beta4 in vernal keratoconjunctivitis.

PURPOSE Thymosin-beta4 (Tbeta4) is a small actin-sequestrating peptide that modulates inflammation and healing in different tissues. The aim of this study was to investigate the molecular and biochemical expression of Tbeta4 in the healthy conjunctiva and in the conjunctiva of patients with vernal keratoconjunctivitis (VKC), a severe allergic eye disease characterized by chronic inflammation and marked tissue remodeling. METHODS Conjunctival tissues, obtained from seven VKC patients and five sex/age-matched healthy subjects, were evaluated for Tbeta4 expression by relative real time-PCR and light/confocal microscopy. The distribution patterns of Tbeta4 in conjunctival sections as well as Tbeta4 expression by mast cells (AA1), eosinophils (EG2), and fibroblast/myofibroblasts (Thy1/alpha-SMA) in VKC tissues was also evaluated by double immunofluorescence. RESULTS Compared to healthy specimens, Tbeta4 mRNA appeared upregulated in VKC conjunctival biopsies as detected by real-time PCR. In the healthy conjunctiva, Tbeta4 protein expression was confined to the conjunctival epithelium, while a weak staining was observed in the stroma. In VKC conjunctival sections, Tbeta4 immunoreactivity was selectively increased in the stroma where, by confocal analysis of VKC papillary formations, Tbeta4 appeared to be mostly localized in eosinophils and activated fibroblasts/myofibroblasts. CONCLUSIONS Our data provides the first evidence of Tbeta4 expression in the conjunctival tissues. The upregulation of both Tbeta4 mRNA and protein in the conjunctival stroma, and its peculiar localization in eosinophils and myofibroblasts populating VKC lesions, suggest a possible role for Tbeta4 in tissue inflammation and remodeling occurring in VKC.