Altered hyaluronan deposition by bronchial epithelial cells contributes to inflammation during respiratory syncytial virus infection

项目总结/摘要 通常由呼吸道合胞病毒（RSV）引起的下呼吸道感染是呼吸道感染的主要原因。 住院率和死亡率。尽管经过多年的研究， 治疗仍然是支持性护理，目前没有RSV特异性治疗或疫苗可用。细胞 气管上皮细胞（BEC）是RSV的主要靶细胞 感染RSV感染BEC导致随后的BEC损伤，下呼吸道阻塞 与细胞碎片和粘液，并通过募集免疫细胞建立气道炎症 如中性粒细胞进入支气管周围空间。我们实验室最近的研究表明， RSV感染基质细胞如肺成纤维细胞导致细胞外基质的建立 (ECM)富含透明质酸（HA），可促进白细胞的积累和激活， 离体细胞培养模型。此外，我们发现RSV感染后HA积累增加， 与成纤维细胞层更紧密相关，并显示出更大的重链修饰 (HC)这在其他研究中已经被描述为增强ECM的能力， 炎症细胞，并促进肺部的炎症反应。HC-HA的形成是 肿瘤坏死因子刺激基因6（TSG-6）的酶活性，该基因通常不表达 在健康的肺组织中，但在对损伤的反应中被诱导。在我们之前对肺成纤维细胞的工作中，我们已经 表明TSG-6在RSV感染期间上调，用siRNA阻断其诱导降低了TSG-6的表达。 HC-HA的形成量，并减少白细胞的积累。尽管是主要的 RSV感染的靶点，目前还没有研究评估RSV感染对BEC生产的影响， HA或TSG-6诱导HC-HA形成，尽管HC-HA在促进肺功能方面起重要作用， 炎症我们的实验室在HA基质的表征方面具有专业知识， 来自特征良好的儿科供体的人BEC使我们的小组处于一个独特的位置，以评估 BEC衍生的HC-HA对RSV感染后炎症反应的贡献。我们假设 BEC的RSV感染导致HA的产生和积累增加，这反过来将促进BEC的生长。 在离体人细胞培养模型系统中的嗜中性粒细胞的积累和活化。此外，我们将 测试RSV感染BEC将诱导TSG-6表达从而促进BEC表达的假设。 在我们的模型系统中，HC-HA的形成和进一步驱动嗜中性粒细胞的积累和活化。我们 将阻断富含HC-HA的ECM的形成，并且还阻断TSG-6的诱导 为了确定嗜中性粒细胞的积累增加是否是HC-HA 依赖。如果这是真的，那么描述由BEC产生的HC-HA的重要性可能会导致新的靶点， 急性RSV感染期间的治疗干预，并可能适用于其他呼吸道病毒。

PROJECT SUMMARY / ABSTRACT Lower respiratory tract infections commonly caused by respiratory syncytial virus (RSV) are a leading cause of hospitalizations and mortality worldwide in young children. Despite many years of study, the mainstay of treatment remains supportive care and currently no RSV specific treatment or vaccine is available. The cells that line the airways, otherwise known as bronchial epithelial cells (BECs), are the primary target for RSV infection. Infection of the BECs with RSV leads to subsequent BEC damage, obstruction of the lower airways with cellular debris and mucous, and the establishment of airway inflammation by recruitment of immune cells such as neutrophils into the peribronchial space. Recent studies from our laboratory have demonstrated that RSV infection of stromal cells such as lung fibroblasts leads to the establishment of an extracellular matrix (ECM) that is enriched with hyaluronan (HA) which promotes the accumulation and activation of leukocytes in ex vivo cell culture models. Furthermore, we found that the increased HA accumulation following RSV infection was more closely associated with the fibroblast cell layer and displayed greater modification with heavy chains (HC) which has been described in other studies to enhance the ECM’s ability to become sticky for inflammatory cells and promotes the inflammatory response in the lung. The formation of HC-HA is the result of the enzymatic activity of tumor necrosis factor stimulated gene 6 (TSG-6), which is not normally expressed in healthy lung tissue, but is induced in response to injury. In our previous work with lung fibroblasts, we have shown that TSG-6 is upregulated during RSV infection and blocking its induction with siRNA decreased the amount of HC-HA that was formed and decreased the accumulation of leukocytes. Despite being the primary target of RSV infection, no studies exist that have evaluated the effects of RSV infection on BEC production of HA or TSG-6 induced HC-HA formation despite the important role that HC-HA plays in promoting lung inflammation. Our laboratory both has expertise in the characterization of HA matrices and access to primary human BECs from well-characterized pediatric donors placing our group in a unique position to evaluate the contribution of BEC derived HC-HA to the inflammatory response following RSV infection. We hypothesize that RSV infection of BECs leads to increased production and accumulation of HA which will in turn promote the accumulation and activation of neutrophils in an ex vivo human cell culture model system. Additionally, we will test the hypothesis that RSV infection of BECs will induce the expression of TSG-6 thereby promoting the formation of HC-HA and further drive the accumulation and activation of neutrophils in our model system. We will pharmacologically block the formation of HC-HA enriched ECMs and also block the induction of TSG-6 during RSV infection in order to establish whether the increased accumulation of the neutrophils is HC-HA dependent. If true, characterizing the importance of HC-HA produced by BECs may lead to novel targets for therapeutic intervention during acute RSV infections and may be applicable to other respiratory viruses.