The antioxidant ergothioneine alleviates cisplatin-induced hearing loss through the Nrf2 pathway

Aims: Cisplatin (CDDP) is a commonly used chemotherapeutic agent for treating head and neck tumors. However, there is high incidence of ototoxicity in patients treated with CDDP, which may be caused by the excessive Reactive Oxygen Species generation (ROS) in the inner ear. Many studies have demonstrated the strong antioxidant effects of ergothioneine (EGT). Therefore, we assumed that EGT could also attenuate CIHL as well. However, the protective effect and mechanism of EGT on CIHL have not been elucidated as so far. In this study, we investigated whether EGT could treat CIHL and the mechanism.

Results: In our study, we confirmed the protective effect of EGT on preventing cisplatin induced toxicity both in vitro and in vivo. The auditory brainstem response (ABR) threshold shift in the EGT + CDDP treatment mice was 30 dB less than that in the CDDP treatment mice. EGT suppressed production of ROS and pro-apoptotic proteins both in tissue and cells. By silencing Nrf2, we confirmed that EGT protected against CIHL via the Nrf2 pathway. We also found that SLC22A4 (OCTN1), an important molecule involved in transporting EGT, was expressed in the cochlea.

Innovation: Our results revealed the role of EGT in the prevention of CIHL by activating Nrf2/HO-1/NQO-1 pathway, and broadened a new perspective therapeutic target of EGT.

Conclusion: EGT decreased ROS production and promoted the expression of antioxidative Enzymes to maintain redox homeostasis in sensory hair cells (HCs). Overall, our results indicated that EGT may serve as a novel treatment drug to attenuate CIHL.