Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Stanford University, Palo Alto, CA, 94305, USA.
J Neuroinflammation. 2024 Sep 14;21(1):223. doi: 10.1186/s12974-024-03212-6.
The activation of the NLRP3 inflammasome has been linked to several inflammatory and autoinflammatory diseases. Despite cases of potential hearing improvement in immune-mediated diseases, direct evidence of the efficacy of targeting this mechanism in the inner ear is still lacking. Previously, we discovered that macrophages are associated with Sensorineural Hearing loss (SNHL) in Chronic Suppurative Otitis Media (CSOM), the leading cause of this permanent hearing loss in the developing world and incurring costs of $4 to $11 billion dollars in the United States. However, the underlying mechanism remained unknown. Here, we investigate how macrophages drive permanent hearing loss in CSOM. We first confirmed the occurrence of NLRP3 inflammasome activation in cochlear macrophages in CSOM. We then revealed that Outer Hair Cells (OHCs) were protected in CSOM by macrophage depletion and subsequently confirmed the same protection in the NLRP3 knockout condition. Furthermore, we showed that therapeutic inhibition of NLRP3 inflammasome activation and downstream inhibition of IL-1β protects OHCs in CSOM. Collectively, our data demonstrates that the main driver for hearing loss in CSOM is NLRP3 inflammasome activation in cochlear macrophages and this is therapeutically targetable, leading the way for the development of interventions to prevent the leading cause of permanent hearing loss and a costly disease in the developed world.
NLRP3 炎性小体的激活与几种炎症性和自身炎症性疾病有关。尽管在免疫介导的疾病中存在潜在的听力改善病例,但针对内耳这一机制的疗效的直接证据仍然缺乏。此前,我们发现巨噬细胞与慢性化脓性中耳炎(CSOM)中的感觉神经性听力损失(SNHL)有关,CSOM 是发展中国家导致这种永久性听力损失的主要原因,在美国造成的损失为 40 亿至 110 亿美元。然而,其潜在机制尚不清楚。在这里,我们研究了巨噬细胞如何导致 CSOM 中的永久性听力损失。我们首先证实了 NLRP3 炎性小体在 CSOM 中的耳蜗巨噬细胞中的激活。然后,我们揭示了巨噬细胞耗竭可保护 CSOM 中的外毛细胞(OHC),随后在 NLRP3 基因敲除条件下也证实了同样的保护作用。此外,我们还表明,NLRP3 炎性小体激活的治疗性抑制和下游的白细胞介素 1β抑制可保护 CSOM 中的 OHC。总之,我们的数据表明,CSOM 中听力损失的主要驱动因素是耳蜗巨噬细胞中 NLRP3 炎性小体的激活,这是一种可治疗的靶点,为开发预防发达国家中导致永久性听力损失和昂贵疾病的主要原因的干预措施铺平了道路。