Increased transforming growth factor-beta2 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 participate in regulating hormone synthesis and release, little is known about involvement of individual human TGF-beta isoforms, TGF-beta1, -beta2, and -beta3, in renin synthesis and release. We examined expression of these TGF-beta isoforms in a 50-year-old man with a Bartter's-like syndrome whose renal biopsy specimen showed hyperplasia of the juxtaglomerular apparatus (GA), mild mesangial hypercellularity, focal tubular atrophy, and interstitial fibrosis. Immunoreactivity for renin and marked expression of TGF-beta2 mRNA were noted in the glomerular arteriole of the JGA, whereas mRNA expression for TGF-beta1 was only slight and that for TGF-beta3 was still more faint. Expression of mRNAs for all 3 TGF-beta isoforms was increased in the fibrotic interstitium. This expression pattern suggests that TGF-beta2 may be involved in inducing renin synthesis and/or release in the glomerular arteriole of the JGA.