Role of Spiral Ligament Fibrocytes in Inner Ear Inflammation

描述（由申请人提供）：炎症与许多病因不明的内耳疾病有关。据认为，中耳炎（OM）相关的内耳炎症导致高达3%的OM患者出现高频感音神经性听力损失（SNHL）。此外，由于常规听力测试难以检测到超高频SNHL和瞬态听力阈值移动，因此发病率可能被低估。然而，究竟是哪一种内耳细胞通过识别细菌分子和募集炎症细胞参与内耳炎症尚不清楚。螺旋韧带纤维细胞（slf）产生炎症介质，如MCP1，吸引单核细胞。单核细胞主要浸润耳蜗慢性OM或听觉创伤。这使得MCP1成为理想的slf衍生趋化因子，吸引效应细胞并引起内耳损伤。不可分型流感嗜血杆菌（NTHI）是诱发内耳炎症的模式生物，是OM的主要病原体之一。有趣的是，toll样受体2 （TLR2）在识别上皮细胞中的NTHI分子中起着重要作用，即使它是革兰氏阴性细菌。我们假设slf识别NTHI分子并通过tlr2依赖性NF释放MCP1。B激活。此外，我们假设nthi诱导的MCP1上调参与OM继发性内耳炎症，导致SNHL。因此，我们提出以下三个具体目标来检验我们的假设：；

DESCRIPTION (provided by applicant): Inflammation is associated with many inner ear disorders of unknown etiology. It is believed that otitis media (OM)-associated inner ear inflammation results in high frequency sensorineural hearing loss (SNHL) in as high as 3% of OM patients. Moreover, the incidence can be underestimated because ultrahigh-frequency SNHL and transient hearing threshold shifts are hard to detect with routine hearing tests. However, it is not well known which type of inner ear cells involved in inner ear inflammation by recognizing bacterial molecules and recruiting inflammatory cells. The spiral ligament fibrocytes (SLFs) produce inflammatory mediators such as MCP1, attracting monocytes. Monocytes predominantly infiltrate cochlea with chronic OM or acoustic trauma. This makes MCP1 the ideal SLF-derived chemokine, attracting effector cells and causing inner ear damage. Nontypeable Haemophilus influenzae (NTHI) is the model organism for inducing inner ear inflammation, which is one of the major OM pathogens. Interestingly, toll-like receptor 2 (TLR2) plays a significant role in recognizing NTHI molecules in the epithelial cells even though it is a Gram-negative bacterium. We hypothesize that SLFs recognize NTHI molecules and release MCP1 through TLR2-dependent NF?B activation. Furthermore, we hypothesize that NTHI-induced MCP1 up-regulation is involved in inner ear inflammation secondary to OM, resulting in SNHL. We therefore propose the following three Specific Aims to test our hypotheses:; 1. Do SLFs release MCP1 upon recognition of NTHI through the TLR2-dependent signaling pathway? We will determine TLR2 expression in the cochlea and involvement of the TLR2-MyD88 signaling pathway in recognizing NTHI molecules by SLFs in both in vitro and in vivo models. 2. Does NTHI-induced MCP1 up-regulation require NF?B activation mediated by I?K¿-dependent I?Ba phosphorylation? We will investigate the involvement of I?K¿-dependent I?Ba phosphorylation in NTHI-induced MCP1 up- regulation and identify the specific NF?B subunits and binding sites that are responsive to NTHI. 3. Does the blockage of NTHI-induced MCP1 up-regulation prevent inner ear inflammation secondary to OM We will determine if the presence of NTHI lysate and MCP1 in the middle ear cavity cause inner ear inflammation, resulting in SNHL and explore the possibility of blocking TLR2 and depleting MCP1 to inhibit NTHI-induced SNHL. We believe that this project can shed light on the molecular pathogenesis of inner ear complications secondary to OM. Furthermore, the findings will facilitate future development of novel therapeutic strategies to prevent potential inner ear complications of OM. The goal of this project is to study how middle ear infection affects the inner ear. We aim to investigate the molecular pathogenesis related to bacterial recognition in the inner ear, inner ear inflammation, inner ear damage and hearing loss.