NDT Advance Access published online on January 28, 2009
Nephrology Dialysis Transplantation, doi:10.1093/ndt/gfn754
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Lack of association between TGF-β-1 genotypes and microalbuminuria in essential hypertensive men
Dipartimento Cardio Toracico e Vascolare and 1Endocrinologia e Metabolismo, Università di Pisa, Italy
Correspondence and offprint requests to: Roberto Pedrinelli, Dipartimento Cardio Toracico e Vascolare, Università di Pisa, Italy. Tel: +39-050-996712; Fax: +39-050-540522; E-mail: r.pedrinelli{at}med.unipi.it
| Abstract |
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Background. Polymorphisms within the gene for transforming growth factor (TGF)-β-1, a pro-fibrogenic cytokine pathophysiologically involved in hypertension and hypertensive target damage, might modulate the biological activity of the encoded protein. Through that mechanism, they might contribute to microalbuminuria, a marker of subclinical renal damage and a correlate of systemic inflammation and endothelial dysfunction in hypertension, a possibility never before tested. For this reason, we assessed the association of four TGF-β-1 polymorphic variants (C-509T, Leu10
Pro, Arg25
Pro, Thr263
Ile) with albuminuria in uncomplicated essential hypertensive men, using (circulating active + acid-activatable latent) TGF-β-1 levels as an indirect index of their in vivo biological activity. Because of the close pathophysiological link of TGF-β-1 with the renin–angiotensin system, we also tested the behaviour of the angiotensin converting enzyme (ACE) deletion/insertion (D/I) polymorphism.
Methods. Albuminuria (three overnight collections), office and 24-h BP, left ventricular mass index (LVMI), BMI, renal function, glucose, lipids, plasma TGF-β-1 (n = 162, ELISA) were measured in 222 genetically unrelated, never-treated, uncomplicated Caucasian hypertensive men. ACE D/I polymorphisms were analysed by the polymerase chain reaction technique or a 5' nuclease assay with further restriction analysis when required.
Results. Urine albumin levels or microalbuminuria (albuminuria
15 µg/min) did not differ by TGF-β-1 genotypes, but both parameters were more frequent in ACE D/D homozygotes. Plasma TGF-β-1 was similar across genetic backgrounds and was unrelated to albuminuria. Cardiovascular, renal, metabolic parameters were homogeneously distributed across genotypes.
Conclusions. In contrast to its link with the ACE D/I genotype, microalbuminuria was independent of TGF-β-1 polymorphism in this group of never-treated, uncomplicated essential hypertensive men.
Keywords: angiotensin converting enzyme deletion/insertion polymorphism; circulating TGF-β-1 levels; hypertensive target organ damage; microalbuminuria; TGF-β-1 polymorphisms
Received for publication: 26. 9.08
Accepted in revised form: 15.12.08