Curcumin Ameliorates Kidney Function and Oxidative Stress in Experimental Chronic Kidney Disease

Chronic kidney disease (CKD) is known to involve inflammation, oxidative stress and apoptosis. Here, we investigated the impact of curcumin (diferuloyl methane, a phenolic turmeric pigment), which has strong antioxidant, anti-inflammatory and anti-apoptotic activities on kidney structure and function in rats with adenine-induced CKD. Rats were treated for 5 weeks with adenine to induce CKD-like renal damage and combined with three doses of curcumin. Markers of kidney function and oxidative stress were quantified in plasma, urine, renal homogenates and on kidney tissue. Curcumin was found to significantly abate adenine-induced toxic effects such as reduced creatinine clearance, elevated neutrophil gelatinase-associated lipocalin levels and raised urinary N-acetyl-β-D-glucosaminidase activities. Curcumin markedly reduced renal morphological damage and histopathological markers of inflammation, fibrosis and apoptosis. Curcumin further reduced adenine-induced hypertension, urinary albumin, the inflammatory cytokines IL-1β, IL-6 and TNF-α, cystatin C and adiponectin. It restored plasma sclerostin concentrations and lowered oxidative stress in renal homogenates. In animals treated with the two higher curcumin concentrations, alone or in combination with adenine, an increased expression of the antioxidative transcription factor Nrf2 was found as well as up-regulation of the activity of its direct target glutathione reductase, and of an indirect target, the glutathione level. In conclusion, curcumin exhibits salutary effects against adenine-induced CKD in rats by reducing inflammation and oxidative stress via up-regulation of the transcription factor Nrf2.