Transforming growth factor-β1 levels in hypertensive patients: association with body mass index and leptin

Background: Transforming growth factor-beta(1) (TGF-beta(1)) has been demonstrated to be overexpressed in hypertension. Leptin, an adipocyte product, has been shown to play a role in obesity-related hypertension and in vitro studies demonstrated a biologic interaction between leptin and TGF-beta(1). Thus, we evaluate a possible in vivo association between TGF-beta(1), body mass index (BMI), and leptin circulating levels in hypertensive subjects. Methods: Blood samples for fasting leptin and TGFbeta(1), were evaluated in 29 overweight, 46 obese, and 29 nonobese hypertensive patients before and after a 12-week calorie-restricted diet. Monocyte cultures were used for in vitro experiments. Results: Transforming growth factor-beta(1) was significantly elevated in hypertensive obese patients (n = 46) as compared with TGF-beta(1) levels of hypertensive patients with normal BMI (n = 29) (8.9 +/- 3 ng/mL v 4.4 +/- 2; P < .001). The circulating levels of TGF-beta(1) were associated with BMI and leptin levels in an univariate analysis (r = 0.59, P < .0001; r = 0.62, P < .0001, respectively) and these associations were still present after stepwise multivariate analysis. Weight loss of 10% produced a parallel decrease in TGF-beta(1) (from 8.9 +/- 3 ng/mL to 5.3 +/- 2.8 ng/mL; P < .01) and leptin levels (from 30 +/- 24 ng/mL to 17 +/- 14; P < .05). In vitro experiments showed that leptin is able to induce a dose-dependent increase in TGF-beta(1) production and mRNA expression in human monocyte cultures. Conclusions: Our data indicate that TGF-beta(1) levels are positively associated with BMI and leptin levels in hypertensive patients and suggest that adipose tissue may be an important determinant of TGF-beta(1) levels possibly by a leptin-dependent pathway. (C) 2002 American Journal of Hypertension, Ltd.