Sarcoglycan subcomplex expression in refluxing ureteral endings.

PURPOSE: Functional and structural lesions of ureteral endings seem to alter the active valve mechanism of the ureterovesical junction, causing vesicoureteral reflux. The interaction of the dystroglycan complex with components of the extracellular matrix may have an important role in force transmission and sarcolemma protection, and the sarcoglycan complex is an essential component of the muscle membrane located dystroglycan complex. We performed immunofluorescence and molecular analysis on the expression of sarcoglycan complex subunits. MATERIALS AND METHODS: A total of 21 specimens of refluxing ureteral endings were obtained during ureteral reimplantation. Six ureteral ends obtained during organ explantation were used as controls. Immunohistochemical analysis and reverse transcriptase polymerase chain reaction evaluation were performed for alpha, beta, gamma, delta and epsilon-sarcoglycan complex. RESULTS: The Spearman test revealed a significant positive correlation between alpha-sarcoglycan complex immunofluorescence intensity and grade of vesicoureteral reflux, while a negative correlation was recorded between epsilon-sarcoglycan complex immunofluorescence intensity and grade of vesicoureteral reflux. CONCLUSIONS: Semiquantitative analysis demonstrated a significant grade related impairment of epsilon-sarcoglycan complex coupled with an increased expression of alpha-sarcoglycan complex. This observation suggests that the structural deficiency of the trigonal ureterovesical junction could cause a passive stretching of refluxing urine on the ureter, deranging the multimodular tensegrity architecture of the sarcoglycan subcomplex, or that the sarcoglycan complex could have a key role in the physiopathology of vesicoureteral reflux. In fact, the defect in any of the sarcoglycan complexes results in degeneration of membrane integrity and muscle fiber. An altered configuration of the sarcoglycan complex could explain the structural and functional changes in refluxing ureteral endings. Our observations underline the assumption that primary vesicoureteral reflux might be regarded as a sarcoglycanopathy with marked quantitative deficiency of epsilon-sarcoglycan complex and over expression of alpha-sarcoglycan complex.