Benamer Najate, Le Ribeuz Hélène, Felgerolle Chloé, Calvet Charlotte, Postal Olivier, Plion Baptiste, Saenz-Roldan Mauricio, Giorgi Marie, Lecomte Marie-José, Nguyen Yann, Petit Christine, Michalski Nicolas, Gourévitch Boris, Akil Omar, Safieddine Saaid
Université Paris Cité, Institut Pasteur, AP-HP, INSERM, CNRS, Fondation Pour l'Audition, Institut de l'Audition, IHU reConnect, Paris, F-75012, France.
Sorbonne Université, Collège Doctoral, Paris, F-75005, France.
Commun Med (Lond). 2025 Jun 12;5(1):229. doi: 10.1038/s43856-025-00926-3.
The autosomal recessive deafness 9 (DFNB9) is caused by mutations in the otoferlin gene that accounts for 2-8% of all inherited deafness cases. In a previous study, we demonstrated that Adeno-associated virus (AAV) gene therapy restored hearing in a preclinical mouse model of profound DFNB9 deafness caused by a frameshift mutation leading to a complete loss of otoferlin expression. However, it remains to be demonstrated that it can address the full spectrum of DFNB9 deafness severity, while also restoring central auditory processing essential for speech understanding.
Using homologous recombination in mouse embryonic stem cells, we created a knock-in mouse model carrying the E1799del otoferlin mutation, which mirrors the human E1804del variant linked to DFNB9 deafness, characterized by moderate-to-profound deafness during febrile episodes in affected individuals. A mixture of male and female mice was used at P2, P8, and P30. Some were followed for up to 4 months for longevity monitoring and behavioral tests.
The mouse model exhibits abnormal otoferlin distribution, failure of synaptic transmission in inner hair cells, and profound hearing loss, all of which is restored to normal through AAV gene therapy. Notably, we conduct objective behavioral testing to provide the first evidence that gene therapy administered to the cochlea, which is part of the peripheral auditory system, can restore frequency discrimination, indicating the recovery of central auditory processing. This is achieved even when treatment is administered late at the end of the critical period.
These findings indicate that gene therapy can address the entire spectrum of DFNB9 hearing loss, and that profound deafness during critical period may not impede the restoration of central auditory processing.
常染色体隐性遗传性耳聋9型（DFNB9）由 otoferlin 基因突变引起，占所有遗传性耳聋病例的2% - 8%。在先前的一项研究中，我们证明腺相关病毒（AAV）基因疗法可恢复由移码突变导致 otoferlin 表达完全丧失而引起的深度DFNB9耳聋的临床前小鼠模型的听力。然而，仍有待证明其能否解决DFNB9耳聋严重程度的全谱问题，同时恢复对语音理解至关重要的中枢听觉处理能力。
利用小鼠胚胎干细胞中的同源重组，我们创建了一个携带 E1799del otoferlin 突变的敲入小鼠模型，该突变反映了与DFNB9耳聋相关的人类 E1804del 变体，其特征是受影响个体在发热发作期间出现中度至深度耳聋。在出生后第2天（P2）、第8天（P8）和第30天使用雄性和雌性小鼠的混合群体。一些小鼠被跟踪长达4个月以进行寿命监测和行为测试。
该小鼠模型表现出otoferlin分布异常、内毛细胞突触传递失败以及深度听力损失，所有这些通过AAV基因疗法均可恢复正常。值得注意的是，我们进行了客观行为测试，以提供首个证据表明给予作为外周听觉系统一部分的耳蜗的基因疗法可恢复频率辨别能力，这表明中枢听觉处理能力得到恢复。即使在关键期结束时进行晚期治疗也能实现这一点。
这些发现表明基因疗法可以解决DFNB9听力损失的全谱问题，并且关键期的深度耳聋可能不会阻碍中枢听觉处理能力的恢复。
