Overexpression of the transforming growth factor-beta-inducible gene beta ig-h3 in anterior polar cataracts

PURPOSE. In anterior polar cataracts and the fibrosis that can occur after cataract surgery, lens epithelial cells synthesize abundant extracellular m atrix molecules and transdifferentiate into myofibroblast-like cells. Trans forming growth factor (TGF)-beta has been implicated as a key player in the se cataractous changes. The purpose of this study was to determine whether the TGF-beta-inducible gene h3 (beta ig-h3) is expressed in lens epithelial cells from patients with anterior polar cataracts and to test whether beta ig-h3 is induced by TGF-beta in cultured lens epithelial cells. METHODS. Lens epithelial cells attached to the anterior capsules of human c ataractous lenses and noncataractous lenses were examined for the expressio n of beta ig-h3 mRNA and protein using reverse transcription-polymerase cha in reaction and immunohistochemical analyses. The effect of TGF-beta on bet a ig-h3 gene expression was also tested in human lens epithelial B-3 cells using Northern and Western blot analyses. RESULTS. beta ig-h3 mRNA was not detected in lens epithelial cells from pat ients with clear lenses or patients with nuclear cataracts. Significant exp ression of mRNA for beta ig-h3 was observed in lens epithelial cells from p atients with anterior polar cataracts. Immunohistochemical analysis using a nti-beta ig-h3 antiserum indicated that beta ig-h3 protein was present with in the subcapsular plaques of anterior polar cataracts. Treatment of human lens epithelial B-3 cells with TGF-beta 1 led to an increase in beta ig-h3 mRNA and the secretion of beta ig-h3 protein into the culture medium. CONCLUSIONS. beta ig-h3 may serve as a marker for anterior polar cataracts in addition to previously known proteins, fibronectin, type I collagen, and ct-smooth muscle actin. The functions of this protein in lens pathology ne ed to be further investigated.