Blockade of TGF-β signaling in T cells prevents the development of experimental glomerulonephritis

Anti-glomerular basement membrane (GBM) Ab-induced glomerulonephritis (GN) at late stage is thought to be mediated by T cells. However, signaling pathways of T cells that are involved in the development of anti-GEM Ab-induced GN are unclear, We have recently established transgenic mice expressing Smad7, an inhibitor of TGF-beta signaling, in mature T cells, where signaling by TGP-beta was blocked specifically in T cells. In this study, we showed that anti-GEM Ab-induced GN was suppressed in several measures in the transgenic mice including the severity; of glomerular changes, proteinuria, renal function, and; CD4 T cell infiltration into the glomeruli without down-regulation of CD62 ligand (CD62L) (L-selectin) expression on CD4 T cells. Furthermore, treatment,vith the soluble fusion protein of CD62L and IgG enhanced anti-GEM Ah-induced GN, These findings indicated that blockade of TGF-beta signaling in T cells prevented the development of anti-GEM Ah-induced GN, Because CD62L on T cells appears to be inhibitory for the development of anti-GEM Ah-induced GN, persistent expression of CD62L on CD4 T cells may explain, at least in part, the suppression of anti-GEM Ab-induced GN in the transgenic mice. Our findings suggest that the development of anti-GEM Ab-induced GN requires TGF-beta /Smad signaling in T cells.