Link between angiotensin II and TGF-beta in the kidney.
Glomerulosclerosis and tubulointerstitial fibrosis are common morphological correlates of many end-stage kidneys. There is ample evidence that transforming growth factor-beta (TGF-beta) plays a major role in these alterations by directly stimulating synthesis of many extracellular matrix components and reducing collagenase production, finally leading to renal scarring. Although many factors may induce TGF-beta expression in the kidney, one very interesting aspect is the link between angiotensin II (ANG II) and TGF-beta. Originating from observations in vascular smooth muscle cells, there are now several additional studies showing that ANG II stimulates TGF-beta expression in the kidney. Although cell culture studies have convincingly demonstrated that the vasoactive peptide directly stimulates transcription as well as bioactivation of TGF-beta, the in vivo evidence is more indirect. Nevertheless, there are several pathophysiological situations including unilateral ureteral obstruction, chronic cyclosporin A nephrotoxicity, various models of hypertension, and probably diabetic nephropathy in which ANG II-mediated TGF-beta induction has been demonstrated to play an important role in the progression of the disease. The fascinating aspect of this relationship between ANG II and TGF-beta is the fact that hemodynamic changes as well as structural changes are linked together generating a unifying model of progression of chronic renal failure with ANG II as the key player. Angiotensin-converting enzyme (ACE) inhibitor and the more recently introduced AT1-receptor blocker may be potential drugs to interfere with this ANG II-mediated TGF-beta expression. Therefore, these drugs should not only be considered as antihypertensive medications, but should rather be viewed as renoprotective substances influencing renal remodeling by preventing local TGF-beta expression.
Wolf
G
G
Department of Medicine, University of Hamburg, Germany. wolf@uke.uni-hamburg.de
D000804:Angiotensin II / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007668:Kidney / Q000378:metabolism / Q000473:pathology; D007676:Kidney Failure, Chronic / Q000378:metabolism / Q000473:pathology; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000502:physiology*
D016212:Transforming Growth Factor beta; D000804:Angiotensin II