Curcumin Attenuates Urinary Excretion of Albumin in Type II Diabetic Patients with Enhancing Nuclear Factor Erythroid-Derived 2-Like 2 (Nrf2) System and Repressing Inflammatory Signaling Efficacies

Curcumin has a therapeutic potential in treating diabetic kidney disease (DKD) while potential mechanisms underlining this beneficial effect remain to be elucidated. In the present study, curcumin intervention was performed in patients with Type II diabetes mellitus (T2DM) by oral intake of curcumin at the dose of 500mg/day for a period of 15-30 days. Nephritic excretion of urinary micro-albumin (U-mAlb) and blood metabolic indexes were assessed before and after this intervention. In addition, the lipid oxidation index, malondialdehyde (MDA) in plasma and the status of anti-oxidative Nrf2 system in blood lymphocytes were measured. The effect of curcumin on inflammation was assessed by measuring plasma lipopolysaccharide (LPS) content and inflammatory signaling protein in blood lymphocytes. A self-comparison method was used for assessing statistical significances of these measurements. Here we show that curcumin intervention markedly attenuated U-mAlb excretion without affecting metabolic control of participated patients. In addition, curcumin reduced plasma MDA level with enhanced the Nrf2 system specifically regulated protein, NAD(P)H quinone oxidoreductase 1 (NQO-1) together with other anti-oxidative enzymes in patients' blood lymphocytes. Furthermore, we observed reduced plasma LPS content and increased IB, an inhibitory protein on inflammatory signaling in patient's lymphocytes after curcumin administration. Finally, several gut bacterials important for maintaining gut barrier integrity and function were upregulated by curcumin. In conclusion, short-term curcumin intervention ablates DKD progress with activating Nrf2 anti-oxidative system and anti-inflammatory efficacies in patients with T2DM.