Department of Otolaryngology-Head and Neck Surgery, Chonnam National University Medical School and Chonnam National University Hospital, Gwangju, Korea.
Department of Biomedical Science, College of Medicine, Chonnam National University Graduate School, BK21 PLUS Center for Creative Biomedical Scientists at Chonnam National University, Gwangju, Korea.
PLoS One. 2022 Mar 30;17(3):e0266108. doi: 10.1371/journal.pone.0266108. eCollection 2022.
Methotrexate (MTX) has been used in treating various types of cancers but can also cause damage to normal organs and cell types. Folinic acid (FA) is a well-known MTX antidote that protects against toxicity caused by the drug and has been used for decades. Since hearing loss caused by MTX treatment is not well studied, herein we aimed to investigate the efficiency of the antioxidant Avenanthramide-C (AVN-C) on high-dose MTX (HDMTX) toxicity in the ear and provide insights into the possible mechanism involved in MTX-induced hearing loss in normal adult C57Bl/6 mice and HEI-OC1 cells. Our results show that the levels of MTX increased in the serum and perilymph 30 minutes after systemic administration. MTX increased hearing thresholds in mice, whereas AVN-C and FA preserved hearing within the normal range. MTX also caused a decrease in wave I amplitude, while AVN-C and FA maintained it at higher levels. MTX considerably damaged the cochlear synapses and neuronal integrity, and both AVN-C and FA rescued the synapses. MTX reduced the cell viability and increased the reactive oxygen species (ROS) level in HEI-OC1 cells, but AVN-C and FA reversed these changes. Apoptosis- and ROS-related genes were significantly upregulated in MTX-treated HEI-OC1 cells; however, they were downregulated by AVN-C and FA treatment. We show that MTX can cause severe hearing loss; it can cross the blood-labyrinth barrier and cause damage to the cochlear neurons and outer hair cells (OHCs). The antioxidant AVN-C exerts a strong protective effect against MTX-induced ototoxicity and preserved the inner ear structures (synapses, neurons, and OHCs) from MTX-induced damage. The mechanism of AVN-C against MTX suggests that ROS is involved in HDMTX-induced ototoxicity.
甲氨蝶呤（MTX）已被用于治疗各种类型的癌症，但也会对正常器官和细胞类型造成损害。叶酸（FA）是一种众所周知的 MTX 解毒剂，可防止药物引起的毒性，已使用了数十年。由于 MTX 治疗引起的听力损失尚未得到充分研究，因此，我们旨在研究抗氧化剂 Avenanthramide-C（AVN-C）对高剂量 MTX（HDMTX）耳毒性的作用，并深入了解 MTX 诱导正常成年 C57Bl/6 小鼠和 HEI-OC1 细胞听力损失的可能机制。我们的研究结果表明，MTX 在全身给药 30 分钟后，在血清和外淋巴液中的水平增加。MTX 导致小鼠听力阈值升高，而 AVN-C 和 FA 则将听力保持在正常范围内。MTX 还导致 I 波幅度降低，而 AVN-C 和 FA 则将其维持在较高水平。MTX 极大地损害了耳蜗突触和神经元的完整性，而 AVN-C 和 FA 则挽救了这些突触。MTX 降低了 HEI-OC1 细胞的活力并增加了活性氧（ROS）水平，而 AVN-C 和 FA 则逆转了这些变化。MTX 处理的 HEI-OC1 细胞中与凋亡和 ROS 相关的基因显著上调；然而，它们被 AVN-C 和 FA 处理下调。我们表明，MTX 可导致严重的听力损失；它可以穿过血迷路屏障并导致耳蜗神经元和外毛细胞（OHC）受损。抗氧化剂 AVN-C 对 MTX 诱导的耳毒性具有很强的保护作用，并防止内耳结构（突触，神经元和 OHC）受到 MTX 诱导的损伤。AVN-C 对 MTX 的作用机制表明，ROS 参与了 HDMTX 诱导的耳毒性。
