Smilax glabra roxb. alleviates cisplatin-induced acute kidney injury in mice by activating the Nrf2/HO-1 Signalling Pathway.

Background: Owing to its remarkable efficacy, cisplatin (CDDP) is widely used as a chemotherapeutic drug in clinical cancer treatment; however, its severe nephrotoxicity often leads to acute kidney injury (AKI), in turn adversely affecting patient treatment and quality of life. Smilax glabra Roxb. (TFL), a Chinese herbal medicine, has various pharmacological effects, including antitumour, anti-inflammatory, and antioxidant activities, with the antioxidant activity being of useful in the detoxification of heavy metal toxicity.

Aim: This study aimed to investigate, for the first time, the nephroprotective effects of TFL in alleviating CDDP-induced AKI and to elucidate its underlying mechanisms.

Methods: In vitro and in vivo models of AKI were established using CDDP induction. For the in vivo model, CDDP (20 mg/kg) was intraperitoneally injected on day 7 to induce AKI. TFL treatment was administered daily at doses of 1.95 and 3.9 g/kg starting from the day 1 and continuing for 10 consecutive days. Blood samples were collected on day 10 after 72-h of CDDP injection for analysis. Kidney pathology was observed using haematoxylin and eosin (HE) staining, and mitochondrial ultrastructure was assessed using transmission electron microscopy. The expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2), HO-1, NQO1, caspase-3, and cytochrome C (CYT-C) were determined using western blotting, PCR, and immunofluorescence (IF). Adenosine triphosphate (ATP) levels, mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) were measured using the corresponding kits. Lastly, reverse validation of the Nrf2/HO-1 pathway was performed using the Nrf2-specific inhibitor, ML385.

Results: After induction with 40 μM CDDP, HK2 cells showed obvious mitochondrial damage, and the protein and mRNA expressions of Nrf2, HO-1, and NQO1 were inhibited, but gradually increased with TFL treatment. Furthermore, CDDP-induced AKI in mice was similar to the observations in the in vitro model using HK2 cells. The protective effects of TFL were reversed with ML385 therapy.

Conclusion: In both in vivo and in vitro experiments, TFL activated the Nrf2/HO-1 signalling pathway, promoting the expression of antioxidant enzymes and thereby ameliorating CDDP-induced oxidative stress, mitochondrial dysfunction and renal cell apoptosis.