Luteolin ameliorates hyperuricemic nephropathy by activating urate excretion and Nrf2/HO-1/NQO1 antioxidant pathways in mice

Luteolin is a natural flavonoid, which exists in many plants, including onions, broccoli, carrots, peppers, celery, olive oil, and mint. Luteolin is a dietary flavonoid with potent uric acid-lowering and antioxidant bioactivities. To date, the mechanism by which luteolin alleviates hyperuricemia nephropathy (HN) still needs to be better defined. This study aims to evaluate the therapeutic efficacy of luteolin in a preclinical mouse model and in vitro. Luteolin was administered in the HN mice induced by the combination of potassium oxonate and hypoxanthine to evaluate the potential renoprotective effects in vivo. The NRK-52E cells were stimulated with adenosine for in vitro evaluation. Hematoxylin and eosin staining, biochemical analysis, immunoblotting, immunofluorescence, and immunohistochemistry were performed for the histopathologic and mechanistic investigations. The results suggest that luteolin attenuated tubular dilation and epithelial atrophy in the renal tissue of HN mice. Further, luteolin improved biochemical indicators concerning renal functions and oxidative stress in vivo. Mechanistically, luteolin reduced the renal expressions of KIM-1 and caspase-3. Luteolin activated renal SIRT1/6 cascade and its downstream Nrf2-mediated antioxidant pathway. Furthermore, luteolin elevated the renal expressions of ATP-binding cassette subfamily G isoform 2 protein (ABCG2) and organic anion/cation transporters. In addition, livers of luteolin-treated HN mice exhibited robust inhibition of xanthine oxidase. Together, our study shows that luteolin alleviates renal injury in the HN mice by activating urate excretion and Nrf2/HO-1/NQO1 antioxidant pathways and inhibiting liver xanthine oxidase activity. Thus, luteolin may be a potential agent for the treatment of HN.