Rhinovirus-Induced Chemokine Production and Asthma

病毒性呼吸道感染是急性加重的主要原因，而最常见的病毒是鼻病毒(RV)。RV诱导的白介素8(IL-8)和RANTES的产生与细胞炎症、普通感冒症状的严重程度和呼吸道高反应性的变化密切相关。综上所述，这些提示这些趋化因子在下呼吸道的失调，通过对中性粒细胞和淋巴细胞炎症的影响，是导致呼吸道阻塞和哮喘的主要因素。RV复制诱导趋化因子产生机制的初步实验表明，RV双链RNA(DsRNA)和双链RNA依赖蛋白激酶(PKR)的激活是促进上皮细胞产生IL-8和RANTES的关键事件。基于这些发现，我们假设PKR和RV 3C蛋白酶的dsRNA激活刺激了特异的信号级联[核因子-kappaB(NF-kappaB)；丝裂原激活蛋白激酶(MAPK)，CCAAT/增强子结合蛋白β(C/EBPbeta)]，从而促进上皮细胞IL-8和RANTES的转录。此外，在哮喘中，这一过程的调节缺失，从而导致这些趋化因子的失调产生，并增加了呼吸道炎症和哮喘。为了验证这些假设，我们建议确定dsRNA对未转化的支气管上皮(BE)细胞中RANTES和IL-8基因转录的影响，并选择调节这一过程的转录因子。此外，还将确定3C蛋白酶对抑制蛋白Oct-1的裂解和IL-8转录上调的影响。最后，我们建议评估正常志愿者和哮喘志愿者来源的BE细胞在趋化因子生成和调控方面的差异。总之，这些研究将把RV复制周期中的特定事件和蛋白质与促炎趋化因子的产生联系起来，并确定哮喘对这些过程的影响。通过实现这些目标，拟议的研究将产生更多关于病毒引起的儿童哮喘加重的发病机制的信息，从而确定基因分析和更有效的治疗策略的新靶点。

Viral respiratory infections are the major cause of acute exacerbations, and the virus most often implicated is rhinovirus (RV). RV induced production of interleukin-8 (IL-8) and RANTES correlates closely with cellular inflammation, the severity of common cold symptoms, and changes in airway hyperresponsiveness. Together, these suggest that dysregulation of these chemokines in the lower airway, through effects on neutrophilic and lymphocytic inflammation, is a major factor in causing airway obstruction and asthma. Preliminary experiments conducted to establish mechanisms by which RV replication induces the production of chemokines indicate that RV double-stranded RNA (dsRNA) and activation of the double-stranded RNA-dependent protein kinase (PKR) are key events to increase epithelial cell generation of IL- 8 and RANTES. Based upon these findings, we hypothesize that dsRNA activation of PKR and RV 3C protease stimulate specific signaling cascades [nuclear factor kappa-B (NF-kappaB); mitogen- activated protein kinases (MAPK), CCAAT/enhancer-binding protein beta (C/EBPbeta)] that promote transcription of IL-8 and RANTES by epithelial cells. Furthermore, there is a loss in the regulation of this process in asthma, thus leading to dysregulated generation of these chemokines, and increased airway inflammation and asthma. To test these hypotheses, we propose to determine the effects of dsRNA on RANTES and IL-8 gene transcription, and selected transcription factors which regulate this process, in non-transformed bronchial epithelial (BE) cells. In addition, the effects of 3C protease on the cleavage of the repressor protein Oct-1 and upregulation of IL-8 transcription will be determined. Finally, we propose to evaluate differences in chemokine generation and regulation in BE cells derived from normal and asthmatic volunteers. Together, these studies will link specific events and proteins in the RV replication cycle to the generation of pro- inflammatory chemokines, and determine effects of asthma on these processes. By achieving these goals, the proposed studies will yield additional information about the pathogenesis of virus-induced asthma exacerbations in children, and thereby identify new targets for genetic analyses and more effective therapeutic strategies.