Study of Allergen, Genetics and Endotoxin (SAGE)

描述(申请人提供)：特应性疾病和哮喘在全球范围内的流行率呈上升趋势。与特应性和哮喘的诱导有关，暴露于抗原、内毒素和其他病原体相关分子模式(PAMPs)可诱导先天和获得性免疫反应。事实上，通过先天免疫系统的受体触发的强效过敏原与生物制剂的共同暴露，可能是适应性过敏敏化的必要途径。这些免疫反应由暴露和基因共同控制。在成人中，职业性暴露估计占新发哮喘病例的15%，职业性哮喘是成人哮喘发病的极好模型。从事动物工作的研究科学家和技术人员对实验动物(LA)的症状和敏感率很高，并在工作场所暴露于空气传播的动物过敏原和内毒素。我们建议研究这一群体，因为它是一个模型系统，在其中检查暴露、遗传和与过敏和哮喘相关的生物机制的相互作用。我们最近证明，内毒素是老鼠症状的最强预测因子，特别是在不对老鼠过敏的工作人员中。志愿者的内毒素刺激复制了职业性接触所报告的上呼吸道和下呼吸道症状。在动物中，内毒素与变应原接触会增强过敏性致敏作用，这取决于内毒素的时间和剂量。因此，内毒素既可以作为呼吸道刺激物，也可以作为过敏性致敏的佐剂。Toll样受体4(TLR4)和CD14是两个主要的人类内毒素反应元件。人类TLR4编码区和CD14启动子区域的多态性分别决定了对内毒素和变应原的不同功能反应。与野生型相比，TLR4/896G变异体降低了人的支气管反应性和对内毒素的细胞因子释放。CD14/-159C变异与过敏性疾病的标志相关，尽管在较高的内毒素暴露背景下，CD14/-159T变异与气流受限和血清IgE增加有关。其他，新描述的TLR4和CD14基因变体也可能在这些免疫事件中被证明是重要的，被其他已知的过敏和哮喘基因β2-腺受体、肿瘤坏死因子-α、IL-4、IL-4α和IL-13的影响所改变。这一建议的中心假设是，内毒素和过敏原与特定宿主TLR4和CD14变异以及其他过敏和哮喘相关基因的相互作用决定了工作相关症状、气流受限和对实验室小鼠的致敏风险。这一假设将在研究科学家、实验室技术人员和动物饲养员的横断面研究中得到解决，并在新雇用的工人的试点队列纵向研究中得到解决。在研究实验室和动物设施中对内毒素和老鼠过敏原进行采样将测量所有研究对象的暴露水平，并表征颗粒大小和分布。作为其主要目标，拟议的研究将评估野生型TLR4/896G变异或CD14/-156C或T变异与空气传播内毒素或小鼠过敏原是否与气流受限、症状或对小鼠的过敏有关。作为次要目标，这项研究将评估其他已知的哮喘和过敏相关基因变异对这些健康结果的贡献。一个子目标将通过对CD14和TLR4等位基因分类的受试者进行嵌套病例对照研究，通过检测PBMC对内毒素的体外细胞因子反应来检验基因多态的功能意义。因此，这项研究将确定LA症状和致敏所必需的暴露和遗传风险因素，提供对限制暴露和减少过敏性疾病后果至关重要的信息，并对过敏性致敏和哮喘的过程提供更广泛的洞察。

DESCRIPTION (provided by applicant): Thct worldwide prevalence of atopy and asthma is on the rise. Relevant to the induction of atopy and asthma, exposures to antigens, endotoxin and other pathogen-associated molecular patterns (PAMPs) induce both innate and adaptive immune responses. Indeed, co-exposure of potent allergens with biological agents, triggering through receptors of the innate immune system, may be the necessary pathway for adaptive allergic sensitization. These immune responses are controlled both by exposures and genes. In adults, occupational exposures are estimated to contribute 15% of new asthma cases, and occupational asthma serves as an excellent model for the development of adult onset asthma. Research scientists and technicians who work with animals have high rates of symptoms and sensitization to laboratory animals (LA), and are exposed to airborne animal allergens and endotoxin in the workplace. We propose to study this population because it is a model system in which to examine the interaction of exposures, genetics, and the biological mechanisms relevant to allergic sensitization and asthma. We recently demonstrated that endotoxin is the strongest predictor of symptoms to mice, particularly in workers who are not mouse allergic. Endotoxin challenge in volunteers reproduces upper and lower respiratory symptoms reported from occupational exposures. In animals, endotoxin exposure with allergen potentiates allergic sensitization, depending on the timing and dose of endotoxin. Endotoxin may thus act as both a respiratory irritant and as an adjuvant in allergic sensitization. Toll-like receptor 4 (TLR4) and CD14 are two major human endotoxin response elements. Polymorphisms in the human TLR4 coding region and in the CD14 promoter region dictate different functional responses to endotoxin and to allergen, respectively. The TLR4/896G variant reduces human bronchial responsiveness and cytokine release to endotoxin compared to the wild type. The CD14/-159 C variant is associated with markers of allergic disease, although in the context of higher endotoxin exposure, the CD14/-159 T variant is linked to airflow limitation and increased serum IgE. Other, newly described TLR4 and CD14 gene variants may also prove important in these immunologic events, modified by the effect of the other known allergy and asthma genes beta2-adenoreceptor, TNF-alpha, IL-4, IL-4alpha, and IL-13. The central hypothesis of this proposal is that the interaction of endotoxin and allergen with specific host genetic variants of TLR4 and CD14 and other allergy- and asthma-associated genes determines risk for work-related symptoms, airflow limitation, and sensitization to laboratory mice. This hypothesis will be addressed in a cross-sectional study of research scientists, laboratory technicians, and animal handlers, and in a pilot inception cohort longitudinal study of newly hired workers. Sampling for endotoxin and mouse allergen in research laboratories and the animal facility will measure exposure levels for all study subjects, and characterize particle size and distribution. As its primary objective, the proposed study will assess whether the wild type TLR4/896 G variant or the CD14/-156 C or T variant, in combination with airborne endotoxin or mouse allergen, are associated with airflow limitation, symptoms or sensitization to mice. As a secondary objective, the study will assess the contribution of other known asthma and allergy-related gene variants to these health outcomes. A sub-aim will examine the functional significance of gene polymorphisms, by testing in vitro cytokine responses of PBMCs to endotoxin in a nested case control study of subjects categorized by CD14 and TLR4 alleles. As such, the study will determine those exposures and genetic risk factors necessary for symptoms and sensitization to LA, supply information critical for limiting exposures and reducing allergic disease outcomes, and provide broader insight into the process of allergic sensitization and asthma.