Urinary fibrogenic cytokines ET-1 and TGF-β1 are associated with urinary angiotensinogen levels in obese children.

BACKGROUND

Fibrogenic cytokines are recognized as putative drivers of disease activity and histopathological deterioration in various kidney diseases. We compared urinary transforming growth factor β1 (U-TGF-β1) and endothelin 1 (U-ET-1) levels across body mass index classes and assessed their association with the level of urinary angiotensinogen (U-AGT), a biomarker of intrarenal renin-angiotensin-aldosterone system (RAAS).

METHODS

The was a cross-sectional evaluation of 302 children aged 8-9 years. Ambulatory blood pressure (BP), insulin resistance (HOMA-IR), aldosterone level and renal function were evaluated. U-ET-1, U-TGF-β1 and U-AGT levels were determined by immunoenzymatic methods.

RESULTS

Obese children presented with the lowest levels of U-ET-1 and U-TGF-β1, but the difference was only significant for U-ET-1. In obese children, the median levels of both U-ET-1 and U-TGF-β1 tended to increase across tertiles (T1-T3) of U-AGT (U-ET-1: T1, 19.9 (14.2-26.3); T2, 32.5 (23.3-141.6); T3, 24.8 (18.7-51.5) ng/g creatinine, p = 0.007; U-TGF-β1: T1, 2.2 (1.8-4.0); T2, 4.3 (2.7-11.7); T3, 4.9 (3.8-10.1) ng/g creatinine, p = 0.004]. In multivariate models, in the obese group, U-ET-1 was associated with HOMA-IR and aldosterone and U-AGT levels, and U-TGF-β1 was associated with U-AGT levels and 24 h-systolic BP.

CONCLUSIONS

Whereas the initial hypothesis of higher levels of urinary fibrogenic cytokines in obese children was not confirmed in our study, both TGF-β1 and U-ET-1 levels were associated with U-AGT level, which likely reflects an early interplay between tissue remodeling and RAAS in obesity-related kidney injury.