Role of transforming growth factor-β2 in, and apossible transforming growth factor-β 2 gene polymorphism as a marker of, renal dysfunction in essential hypertension: A study in Turkish patients.

Background: Many studies have shown that transforming growth factor(TGF)-β has a major role in renal scarring in many renal diseases and hypertension.

Objectives: The primary aim of this study was to investigate both the relationship between hypertension and serum and urinary levels of TGF-β2 (a more sensitive isoform for glomeruli than TGF-β1), and the effects of combination therapy with perindopril + indapamide on microalbuminuria, which becomes an early indicator of hypertensive benign nephropathy, and serum and urinary TGF-β2 levels in patients with mild to moderate essential hypertension. In addition, we examined the possible relationship between TGF-β2 gene polymorphism and essential hypertension.

Methods: This study was conducted at the Department of Nephrology, Medical Faculty, Gazi University, Ankara, Turkey. Patients aged ≥18 years with newly diagnosed mild to moderate essential hypertension (systolic/diastolic blood pressure [SBP/DBP] >120/>80 mm Hg) who had not previously received antihypertensive treatment were included in the study. Patients with stage I hypertension received perindopril 2 mg + indapamide 0.625 mg (tablet), and patients with stage lI hypertension received perindopril 4 mg + indapamide 1.125 mg (tablet). All study drugs were given OD (morning) PO with food for 6 months. Serum and urinary TGF-β2 and creatinine levels and serum and urinary albumin levels were measured before and after perindopril + indapamide administration. Amplified DNA fragments of the TGF-β2 primer region were screened using amplification refractory mutation system polymerase chain reaction analysis, and the number of ACA repeats was confirmed by DNA sequencing. Genetic studies were performed using a commercial TGF-β2 kit.

Results: Forty patients were enrolled in the study, and 38 patients (27 women, 11 men; mean [SD] age, 46.3 [6.5] years) completed it. SBP and DBP were significantly decreased from baseline with perindopril/indapamide (both, P < 0.001). Microalbuminuria and urinary TGF-β2 levels also decreased significantly from baseline (P = 0.04 and P < 0.001, respectively), whereas the serum TGF-β2 level did not change significantly. Three patients, all of whom were found to have TGF-β2 gene mutations, had increased urinary TGF-β2 levels despite good blood pressure control.

Conclusions: The results of this study in patients with mild to moderate hypertension suggest that, despite good clinical control of blood pressure, the persistence of microalbuminuria and high urinary TGF-β2 levels might predict renal impairment. When treating these patients, genetic tendencies and possible polymorphisms on the TGF-β2 locus should be kept in mind.