Expression of transforming growth factor-β1 and its receptors related to the ureteric fibrosis in a rat model of obstructive uropathy

Purpose: Transforming growth factor (TGF-β) is a multifunctional cytokine that may stimulate fibroblast proliferation and regulate the synthesis of matrix components. To elucidate the role of TGF-β1 in the process of ureteric fibrosis in obstructive uropathy, we conducted this study. Materials and Methods: The expression of TGF-β1 and TGF-β receptors I, II, III were studied in 54 rats by the method of immunohistochemistry. Results: The degree of smooth muscle hypertrophy and serosa thickening aggravated gradually along the course of ureteric ligation. The expression of TGF-β1 in the serosa layer was noticed from day 7 after ligation. The expression of TGF-β1 and receptors in the serosa layer progressively increased during the period of ureteric obstruction, reached a peak on day 21 after ligation, and then declined. The expression of TGF-β1 and TGF-β receptors (II and III) in the serosa layer was correlated significantly (r = 0.8048 and 0.7974, respectively; p values both <0.0001). The expression of TGF-β1 also correlated significantly with the thickening of serosa layer and the severity of hydroureter (r = 0.6921 and 0.5394, respectively; p values both <0.005). The expression of TGF-β1 and TGF-β receptors in the smooth muscle layer was transient and weak, and the expression of TGF-β1 and TGF-β receptors was accompanied with the fibrosis in the muscle layer. Conclusions: We conclude that TGF-β1 might participate in the progression of ureteric fibrosis in obstructed ureters.