Combinational Regulation of Inflammation in Otitis Media

描述(申请人提供)：中耳炎(OM)是儿童最常见的细菌感染，也是儿童传导性听力损失的主要原因。炎症是OM的一个特征。虽然由细菌引发的适当炎症反应对于根除细菌病原体是必不可少的，但过度的炎症反应显然对宿主有害，因为严重的组织损伤。为了避免过度活跃和有害的炎症反应，必须严格控制炎症。细菌诱导的负反馈调节被认为通过抑制Toll样受体依赖的信号适配器在预防过度活跃的炎症反应中发挥关键作用。然而，炎症负反馈调控在OM发病机制中的分子机制仍不清楚。我们的长期目标是了解炎症在OM发病机制中的诱导和调控的分子机制。在之前的资助期间，我们重点研究了在包括NTHi和肺炎链球菌在内的OM细菌病原体诱导NF-kB依赖的炎症反应中涉及的关键正信号通路。最近我们发现，新近发现的一种新的脱泛素酶CyLD以一种自我调节反馈的方式对NTHi诱导的依赖于NF-kB的炎症反应起负调控作用。有趣的是，在生理条件下，CyLD在中耳中的表达水平很低，但在NTHi的作用下，它的表达显著上调。这些令人鼓舞的初步结果为我们全面研究NTHi诱导的NF-kB依赖炎症在体内外OM发病机制中的负反馈调控机制奠定了坚实的基础(假设和短期目标)。目的1.确定介导NTHi诱导的NF-kB依赖的炎症反应所需的关键受体依赖的信号转接子。目的2.通过与TRAF6/7接头复合体的负交互作用，确定CyLD抑制NTHi诱导的NF-kB依赖的炎症反应的分子机制。目的3.探讨NTHi诱导和调控细胞色素变性的分子机制。总体而言，拟议的研究将为OM炎症严密调控的分子机制提供新的见解，并可能导致OM患者的新治疗策略。

DESCRIPTION (provided by applicant): Otitis media (OM) is the most common childhood bacterial infection and the leading cause of conductive hearing loss in children. Inflammation is a hallmark of OM. Although appropriate inflammatory response triggered by bacteria is essential for eradicating bacterial pathogen, excessive inflammatory response is clearly detrimental to the host due to severe tissue damage. To avoid overactive and detrimental inflammatory response, inflammation must be tightly regulated. Bacteria-induced negative feedback regulation is thought to play a critical role in preventing overactive inflammatory response by inhibiting Toll- like receptor-dependent signaling adaptors. However, the molecular mechanisms underlying the negative feedback regulation of inflammation in the pathogenesis of OM remain unknown. Our Long-term Objective is to understand the molecular mechanisms by which inflammation is induced and regulated in the pathogenesis of OM. During the previous grant period, we focused on investigating the key positive signaling pathways involved in induction of NF-kB-dependent inflammatory response by OM bacterial pathogens including NTHi and S. pneumoniae. Recently we found that CYLD, a newly identified novel deubiquitinase, acts as a negative regulator for NF-kB-dependent inflammatory response induced by NTHi in an autoregulatory feedback manner. Interestingly, CYLD is expressed at low level in middle ear under physiological conditions, but is greatly up-regulated by NTHi. These encouraging preliminary results have thus laid a solid foundation for us to fully investigate the negative feedback regulatory mechanisms by which NTHi-induced NF-kB-dependent inflammation is tightly controlled by CYLD in the pathogenesis of OM in vitro and in vivo (Hypothesis & Short-term Objective). Aim 1. Determine the key receptor-dependent signaling adaptors required for mediating NTHi-induced NF-kB-dependent inflammatory response. Aim 2. Determine the molecular mechanism by which CYLD inhibits NTHi-induced NF-kB-dependent inflammatory response via negative cross-talk with the TRAF6/7 adaptor complex. Aim 3. Determine the molecular mechanisms by which CYLD is induced and regulated by NTHi. Overall, the proposed studies will provide novel insights into the molecular mechanism underlying the tight regulation of inflammation in OM and may lead to new therapeutic strategies for OM patients.