Microbiome and host response signatures for pneumonia among lung transplant recipients

项目摘要 肺炎（PNA）是肺移植（LTx）后死亡的主要原因。气管支气管炎（TB）是 通常在疑似呼吸道感染（RTI）的LTx接受者中诊断， 不符合PNA标准。然而，LTx背景下结核病的决定性病理学证据是 缺乏，并且尚不清楚诊断是否构成一个连贯的疾病实体。此外，LTx中的RTI 接受者在临床上常常难以与没有感染的定植（COL）区分。最近 基于DNA测序的微生物组分析研究表明，PNA的特征在于失去了 下呼吸道中的微生物多样性，以及优势病原体的出现。微生物组和宿主 LTx后与PNA、TB或COL相关的应答标志物是未定义的。初步 研究中，我们确定了支气管肺泡灌洗液（BALF）中的多变量、非培养型特征 来自LTx接受者的样品，其区分PNA和TB与COL，其由16S 微生物组和细胞因子协变量。与COL相比，PNA的特征在于多样性的丧失， 强烈的促炎细胞因子反应。相比之下，结核病的特点是微生物多样性高， 多功能的细胞因子反应不同于PNA。综合来看，初步数据 提示PNA和TB源于不同致病过程，且微生物组和细胞因子 谱分析可用作对培养物和常规标准的诊断标记。的目的 该项目的目的是完善和验证LTx接受者中PNA、TB和COL的多变量特征， 没有机械通风。在具体目标1中，我们将通过执行16S微生物组来改进特征 分析细菌，评估呼吸道病毒的存在，并测量细胞因子反应， BALF样本储存在我们的LTx生物储存库中。研究将通过以下方式扩展我们的初步数据： 包括用于每次诊断和检测呼吸道病毒以及细菌的大量样本， 从而识别更鲁棒且代表LTx群体的特征。我们会委聘 在我们的初步研究中开发了强大的多变量回归分析方法。具体目标 2，我们将验证微生物组和细胞因子的签名，使用一组独立的BALF样本， 生物保藏所和从LTx接受者前瞻性收集的样品。据我们所知，我们是第一个 描述LTx接受者中PNA、TB和COL的微生物组和宿主反应基础。 我们预计，这项研究将为这些诊断定义优化的疾病特异性特征， 不依赖于培养结果。该项目预计将导致多中心试验， 签名，以及LTx以外环境中的研究，例如呼吸机相关RTI患者或 社区获得的PNA。此外，我们的研究结果将提供深入了解可能的致病机制 对于LTx后PNA和TB，这可以为后续的机制研究提供信息。

Project Summary Pneumonia (PNA) is a leading cause of death following lung transplantation (LTx). Tracheobronchitis (TB) is commonly diagnosed in LTx recipients in whom a respiratory tract infection (RTI) is suspected, and diagnostic criteria for PNA are not fulfilled. However, conclusive pathologic evidence for TB in the setting of LTx is lacking, and it is unclear that the diagnosis constitutes a coherent disease entity. Moreover, RTIs in LTx recipients are often difficult to distinguish clinically from colonization in the absence of infection (COL). Recent DNA sequencing-based microbiome profiling studies have revealed that PNA is characterized by loss of microbial diversity in the lower respiratory tract, and emergence of a dominant pathogen. Microbiome and host response markers that are associated with PNA, TB or COL following LTx are undefined. In preliminary studies, we identified multivariable, non-culture-based signatures within bronchoalveolar lavage fluid (BALF) samples from LTx recipients that distinguished PNA and TB from COL, which were comprised of 16S microbiome and cytokine covariates. Compared to COL, PNA was characterized by loss of diversity and a robust pro-inflammatory cytokine response. In contrast, TB was characterized by high microbial diversity and multifunctional cytokine responses that differed from those of PNA. Taken together, the preliminary data suggest that PNA and TB stem from different pathogenic processes, and that microbiome and cytokine profiling may have utility as diagnostic adjuncts to cultures and conventional criteria. The objective of this project is to refine and validate multivariable signatures for PNA, TB and COL among LTx recipients who are not mechanically ventilated. In specific aim 1, we will refine the signatures by performing 16S microbiome profiling for bacteria, assessing the presence of respiratory viruses, and measuring cytokine responses in BALF samples that are banked in our LTx biorepository. Studies will expand upon our preliminary data by including a larger number of samples for each diagnosis and detecting respiratory viruses as well as bacteria, thereby identifying signatures that are more robust and representative of the LTx population. We will employ powerful multivariable regression analysis methodologies developed in our preliminary studies. In specific aim 2, we will validate microbiome and cytokine signatures, using an independent set of BALF samples from the biorepository and samples collected prospectively from LTx recipients. To our knowledge, we are the first group to describe the microbiome and host response underpinnings of PNA, TB and COL in LTx recipients. We anticipate that this study will define optimized, disease-specific signatures for these diagnoses, which are not contingent upon culture results. The project is expected to lead to multi-center trials validating the signatures, and to studies in settings outside of LTx, such as among patients with ventilator-associated RTIs or community-acquired PNA. Furthermore, our results will provide insights into possible pathogenic mechanisms for PNA and TB following LTx, which can inform subsequent mechanistic studies.