Kynurenine/Tryptophan Ratio Predicts Angiotensin Receptor Blocker Responsiveness in Patients with Diabetic Kidney Disease

Figures

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  Figure 1. (A) The serum kynurenine/tryptophan ratio (KTR) revealed a significantly positive correlation with the severity of albuminuria (r = 0.33, p = 0.013). (B) Serum trptophan (Trp) showed a significantly negative correlation with the severity of albuminuria (r = −0.32, p = 0.017). MAU, macroalbuminuria; mau, microalbuminuria; normo, normoalbuminuria.

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  Figure 2. ROC curve analysis was carried out by SPSS (SPSS, Chicago, IL, USA) to determine the best discrimination point of (A) Trp (cut-off value 46.75 μmol/L with sensitivity 61.8% and specificity 77.3%, AUC = 0.704 with 95% CI 0.562–0.846, p = 0.011, SD = 0.073) and KTR (cut-off value 68.5 × 10−3 with sensitivity 50.0% and specificity 86.4%, AUC = 0.687 with 95% CI 0.547–0.827, p = 0.019, SD = 0.071) for predicting MAU. (B) KTR for ARB responsiveness in diabetic patients with MAU (cut-off value 54.7 × 10−3 with sensitivity 90.0% and specificity 50.0%, AUC = 0.729 with 95% CI 0.558–0.899, p = 0.025, SD = 0.087). ROC, receiver operating characteristic; Trp, tryptophan; KTR, kynurenine to tryptophan ratio; ARB, angiotensin receptor blocker; AUC, area under the ROC curve; 95% CI, 95% confidence interval; SD, standard deviation.

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  Figure 3. The kynurenine pathway of tryptophan degradation in mammals. IDO, indoleamine 2,3-dioxygenase; TDO, tryptophan 2,3-dioxygenase; ARB, angiotensin receptor blocker; KAT, kynurenine aminotransferase.