Selective expression of TGF-β2 and TGF-β3 isoforms in early mesangioproliferative glomerulonephritis

Background/Aim: Evidence from ex vivo glomerular analysis has implicated overexpression of transforming growth factor (TGF) beta 1 in progressive renal disease. The roles of TGF-β2 and TGF-β3 are less clear. The purpose of this study was to define the temporal expression and abundance of TGF-β isoforms in both acute and progressive Thy-1 glomerulonephritis during the crucial initiation phase of these models. Methods: Acute Thy-1 glomerulonephritis was induced by a single injection of OX7, while the progressive model was induced by two injections, 7 days apart. Results: Cellular infiltration of glomeruli consisted of transient increases of neutrophils and ED1+ macrophages. The distribution of TGF-β1, TGF-β2, and TGF-β3 revealed distinct differences in normal and nephritic rats. No changes in TGF-β1 staining were observed within glomeruli of either model. In marked contrast, in the one-shot model, TGF-β2 and TGF-β3 stainings increased rapidly, yet transiently, throughout affected glomeruli, followed by more sustained staining in glomerular epithelial cells. Diffuse, transient staining was absent in two-shot glomerulonephritis, but an increase in epithelial cell staining mirrored that seen in the one-shot model. Conclusion: Based on these results, we propose that the effects, formerly thought of as solely due to a single entity, TGF-β1, may be the result of an interplay between individual TGF-β isoforms.