Urinary Excretion of Kidney Aquaporins as Possible Diagnostic Biomarker of Diabetic Nephropathy

Figure 2

The urinary excretion of AQP2 dramatically increases in DN patients and positively correlates with the clinical severity of DN. (a) Urinary AQP2 excretion was measured by ELISA in urine samples of healthy subjects (CTR, ), patients with DM (), patients with NDN (), and patients with DN () and expressed as fmol/mg urine creatinine. All data are reported as mean ± SEM. versus CTR, versus DM, and versus NDN, obtained by Kruskal-Wallis one-way ANOVA test. (b) DN patients were grouped according to the histological changes evaluated by kidney biopsy: DN stage II (), DN stage III (), and DN stage IV () and uAQP2 at each stage compared to uAQP2 in DM and NDN patients. All data are reported as mean ± SEM. and versus CTR, and versus DM, and versus NDN, obtained by Kruskal-Wallis one-way ANOVA test. (c) Linear regression analysis of uAQP2 abundance, as measured by ELISA, with the class of DN (; ). (d) Exosomes were isolated from urine of healthy subjects (CTR, ), patients with DM (), patients with NDN (), and patients with DN () using the two-step differential centrifugation method. Total exosome proteins were resolved on 12% SDS-PAGE and analyzed by Western blotting for AQP2 abundance. (e) Densitometry analysis of the uAQP2 band intensities was normalized for uCr and reported as means ± SEM. versus CTR, versus DM, and versus NDN, obtained by Kruskal-Wallis one-way ANOVA test. (f) DN patients were grouped according to the histological changes evaluated by kidney biopsy: DN stage II (), DN stage III (), and DN stage IV () and densitometry analysis of uAQP2 at each stage compared to uAQP2 in CTR and DM and NDN patients. All data are reported as mean ± SEM. and versus CTR, and versus DM, and and versus NDN, obtained by Kruskal-Wallis one-way ANOVA test. (g) Linear regression analysis of uAQP2 abundance, as semiquantified by Western blotting, with the class of DN (; ).

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