Increased transforming growth factor-beta 2 expression in the glomerular arteriole of the juxtaglomerular apparatus in a Bartter's-like syndrome

Although transforming growth factor-beta (TGF-beta) has been shown to parti cipate in regulating hormone synthesis and release, little is known about i nvolvement of individual human TGF-beta isoforms, TGF-beta 1, -beta 2, and -beta 3, in renin synthesis and release. We examined expression of these TG F-beta isoforms in a 50-year-old man with a Bartter's-like syndrome whose r enal biopsy specimen showed hyperplasia of the juxtaglomerular apparatus (J GA), mild mesangial hypercellularity, focal tubular atrophy, and interstiti al fibrosis. Immunoreactivity for renin and marked expression of TGF-beta 2 mRNA were noted in the glomerular arteriole of the JGA, whereas mRNA expre ssion for TGF-beta 1 was only slight and that for TGF-beta 3 was still more faint. Expression of mRNAs for all 3 TGF-beta isoforms was increased in th e fibrotic interstitium. This expression pattern suggests that TGF-beta 2 m ay be involved in inducing renin synthesis and/or release in the glomerular arteriole of the JGA. (C) 1999 by W.B. Saunders Company.