CD4+ and CD8+ T cell dependent immune mechanisms of rhinovirus-mediated asthma ex

描述（由申请方提供）：与哮喘相关的最大发病率是发生重度、可能危及生命的急性加重。鼻病毒（RV）约占儿童哮喘急性发作的60-70%。尽管当细胞病变性炎症反应叠加在哮喘肺上时，可以预测哮喘加重，但这不是观察到的情况-只有RV感染与哮喘加重一致相关。RV相关的恶化与2型细胞因子特征（IL-4、IL-5和IL-13）增加有关，一种解释是这些细胞因子由RV特异性T细胞本身产生，CD 4+辅助（Th 2样）或CD 8+细胞毒性（Tc 2样）T淋巴细胞。对病毒感染作出反应的T淋巴细胞产生可能对宿主有害的炎症反应。急性加重也与抗炎细胞因子IL-10表达减少有关。IL-10可以控制与旺盛的T细胞反应相关的附带损害。我们认为，感染过程中IL-10的来源可能是效应T细胞本身。目的/假设：我们建议将重点放在RV特异性效应/记忆T细胞产生2型细胞因子和IL-10，预测自然RV感染后哮喘急性发作的发展。我们假设，RV特异性记忆T细胞从儿童和青少年谁开发的RV感染期间恶化释放较高水平的2型细胞因子和/或较低水平的IL-10。我们将确定儿童哮喘谁成为感染RV和验证我们的能力，以确定循环RV特异性的CD 4+辅助和CD 8+细胞毒性T效应淋巴细胞。具体目标#1将招募哮喘儿童和青少年，我们将前瞻性评估RV感染并量化其对哮喘的影响。RV感染将在定期门诊访视和上呼吸道感染提示时通过鼻分泌物定量PCR进行诊断。RV感染的影响将主要评价为乙酰甲胆碱敏感性的变化。我们的初步研究表明，在秋季RV大流行期间，>50%的儿童将表现出感染的证据，其中约一半的感染将与哮喘急性发作相关，定义为乙酰甲胆碱敏感性增加>2倍。具体目标#2将检查RV特异性T细胞协调哮喘恶化的概念。我们将评估急性RV感染后循环RV特异性T记忆细胞的患病率和细胞因子谱。我们将鉴定RV特异性记忆T细胞，并确定其1型（IFN-3）和2型细胞因子（IL-4，-5和-13）的产生。我们将同时定义IL-10的细胞产生。我们认为RV特异性辅助（CD 4+）和细胞毒性（CD 8+）效应/记忆T细胞中的高2型/低IL-10细胞因子谱将预测哮喘急性发作。 公共卫生相关性：产生“普通感冒”的病毒（鼻病毒）是大多数儿童和青少年哮喘恶化的原因，因此，大多数哮喘住院和死亡。这种病毒的这种独特特征的机制是一个谜。尽管只有一小部分哮喘患者有严重急性发作、紧急护理转诊、住院或死亡的风险，但由于我们无法识别高危个体，目前的指南鼓励对除最轻度哮喘患者外的所有患者进行积极的日常治疗。确定鼻病毒与免疫系统相互作用产生哮喘急性发作的机制，对于确定有哮喘急性发作风险的儿童以及最有可能从预防和治疗的特定干预措施中获益的儿童至关重要。

DESCRIPTION (provided by applicant): The greatest morbidity associated with asthma is the occurrence of severe, potentially life- threatening exacerbations. Rhinovirus (RV) accounts for ~60-70% of childhood asthma exacerbations. Although an exacerbation would be predicted whenever a cytopathic inflammatory response is superimposed upon the asthmatic lung, this is not what is observed - and only RV infections are consistently associated with asthma exacerbations. RV-associated exacerbation are linked to the presence of an increased type 2 cytokine signature (IL-4, -5, and -13) and one explanation is that these cytokines are being produced by the RV-specific T cells themselves, either CD4+ helper (Th2-like) or CD8+ cytotoxic (Tc2-like) T lymphocytes. T lymphocytes responding to a viral infection produce inflammatory responses that can be harmful to the host. Exacerbations are also linked to the presence of diminished expression of the anti-inflammatory cytokine IL-10. IL-10 may to control the collateral damage associated with an exuberant T cell response. The source of this IL-10 during infection, we believe, is likely the effector T cells themselves. Objective/Hypothesis: We propose to focus on the production of type 2 cytokines and IL-10 by RV-specific effector/memory T-cells that predict the development of an asthma exacerbation following natural RV infection. We hypothesize that RV-specific memory T cells from children and adolescents who develop an exacerbation during RV infection release higher levels of type 2 cytokines and/or lower levels of IL-10. We will identify children with asthma who become infected with RV and validate our ability to identify circulating RV-specific CD4+ helper and CD8+ cytotoxic T effector lymphocytes. Specific aim #1 will enroll asthmatic children and adolescents who we will prospectively evaluate for RV infections and quantify the impact on their asthma. RV infection will be diagnosed by quantitative PCR of nasal secretions at regular clinic visits and when prompted by upper respiratory infections. Impact of RV infection will be evaluated primarily as change in methacholine sensitivity. Our preliminary studies demonstrate that during the fall RV pandemic >50% of children will demonstrate evidence for infection and ~half of those infections will be associated with an asthma exacerbation defined as a >2-fold increase in methacholine sensitivity. Specific aim #2 will examine the concept that RV-specific T cells orchestrate asthma exacerbations. We will assess the prevalence and cytokine profile of circulating RV-specific T memory cells after acute RV infections. We will identify RV-specific memory T cells and will define their production of type 1 (IFN-3) and type 2 cytokines (IL-4, -5, and -13). We will simultaneously define cellular production of IL-10. We propose that a high type 2/ low IL-10 cytokine profile within RV-specific helper (CD4+) and cytotoxic (CD8+) effector/memory T cells will predict asthma exacerbations. PUBLIC HEALTH RELEVANCE: The virus producing the "common cold" (rhinovirus) is responsible for most childhood and adolescent asthma exacerbations and, as such, most hospitalizations and deaths from asthma. The mechanism responsible for this unique feature of this virus is an enigma. Even though only a small subset of asthmatics is at risk for severe exacerbations, urgent care referral, hospitalization, or death, because of our inability to identify at risk individuals, current guidelines encourage aggressive daily treatment of all but the mildest asthmatics. Identifying the mechanism through which rhinovirus interacts with the immune system to produce an asthma exacerbation is central to identifying children who are at risk for asthma exacerbations and are most likely to benefit from specific interventions for prevention and treatment.