Transforming growth factor β isoforms in human glomerulonephropathies

Transforming growth factor beta (TGF beta) is a multifunctional cytokine for which three isoforms, TGF beta 1, -2 and -3 have been characterized in mammals. Several reports suggest an involvement of TGF beta in the cellular and molecular basis of renal fibrosis. Most of these studies have focused exclusively on TGF beta 1. Here we demonstrate using reverse transcriptase polymerase chain reaction (RT-PCR) that transcripts from all three isoforms of TGF beta were detected in 31 renal biopsies, control tissue and cultured human mesangial cells. A novel alternative transcript of TGF beta 2 was identified in renal tissue. The variation in transcript levels detected using this technique did not exhibit a striking correlation with any specific disease type. In addition, complement deposition and localization (i.e. mesangial or capillary wall) does not appear to have any direct correlation with the occurrence of a particular TGF beta isoform transcript. It is likely that dynamic changes in all TGF beta transcript levels occur in normal and diseased kidneys as a response to physiological and pathological demands. Most investigations have focused on one TGF beta isoform neglecting the contribution of the others. Studies which analyse all known isoforms and their alternative transcripts may establish the interplay between these during the progression of renal disease.