Lung Transplant Microbiome and Chronic Allograft Dysfunction

描述（由申请人提供）：肺移植是许多终末期肺部疾病的唯一长期选择，但慢性同种异体移植物功能障碍表现为e50%的受体在5年内出现闭塞性细支气管炎综合征（BOS），这是长期生存的主要障碍。微生物因素被认为在BOS发病中起着重要作用，基于与某些微生物制剂的关联，与参与微生物防御的宿主基因的联系，以及其他因素。然而，目前对肺微生物与移植结果之间关系的理解受到传统方法的限制，这些方法需要培养或对特定病原体的先验知识，关注单一药物而不是群体，以及缺乏关于肺移植受者中一般同种异体移植物微生物种群的全面和系统的信息，特别是有无BOS的人。近年来，利用不依赖培养的分子方法的进展揭示了多种生态位微生物种群及其在健康和疾病中的作用，但尚未应用于肺移植。我们的团队已经将这项新兴技术应用于肠道、血液和呼吸道中复杂的细菌、真菌和病毒种群。我们开发了新的高严格采样，测序和分析方法，通过支气管镜检查确定下呼吸道（LRT）中的微生物种群，包括解决LRT分析中的挑战的方法，如上呼吸道携带和环境源混合；识别富含肺部或独特生物体的工具；初步数据揭示了异体肺移植中富集的异常群落和特定类群。我们的假设是，肺移植后异常的LRT微生物组建立，并且群落组成的特定特征与BOS的发展有关，这可以通过使用高严格性方法的系统培养独立方法来识别。我们的具体目标是：(1)确定移植后第一年肺移植受者建立的呼吸道微生物组；(2)前瞻性地确定同种异体移植物微生物群与BOS后续发展的关系；(3)在发生BOS的移植受者与未发生BOS的移植受者的病例对照中，确定移植物功能障碍时的下呼吸道微生物组。该提案利用了两个高度协同的项目-肺移植临床研究和深度测序微生物组研究-其长期目标是提供对肺移植呼吸道微生物种群及其在BOS中的作用的关键理解，BOS是长期移植成功的主要障碍。

DESCRIPTION (provided by applicant): Lung transplantation is the only long-term option for many end stage lung diseases, but chronic allograft dysfunction manifest as bronchiolitis obliterans syndrome (BOS) develops in e50% of recipients by 5 years and is the principal barrier to long term survival. Microbial factors are believed to play an important role in BOS pathogenesis, based on associations with certain microbial agents, linkage to host genes involved in microbial defense, and other factors. However, current understanding of the relationship between lung microbes and transplant outcome is limited by reliance on traditional methods requiring culture or a priori knowledge of specific pathogens, focus on single agents rather than communities, and an absence of comprehensive and systematic information on allograft microbial populations in lung transplant recipients in general and specifically in those with vs without BOS. Recent advances using culture-independent molecular approaches are revealing remarkable insights into microbial populations in multiple ecological niches and their roles in health and disease, but have not been applied to lung transplantation. Our group has applied this emerging technology to complex bacterial, fungal & viral populations in gut, blood and, recently, the respiratory tract. We have developed novel high stringency sampling, sequencing & analytic approaches to define microbial populations in the lower respiratory tract (LRT) by bronchoscopy, including methods to account for challenges in LRT analysis such as upper respiratory tract carryover & environmental source admixture; tools to identify lung-enriched or unique organisms; and preliminary data revealing aberrant communities and specific taxa enriched in lung transplant allografts. Our hypothesis is that an abnormal LRT microbiome is established following lung transplant, and that specific features of community composition are associated with the development of BOS, which can be identified through systematic culture-independent methodology utilizing high stringency approaches. Our specific aims are to: (1) Define the respiratory tract microbiome established in lung transplant recipients over the first year post-transplant; (2) Determine prospectively the relationship between the allograft microbiome populations and subsequent development of BOS; (3) Define the lower respiratory tract microbiome at the time of graft dysfunction in a case-control of transplant recipients experiencing BOS compared with recipients without BOS. The proposal leverages two highly synergistic programs - lung transplant clinical research, and deep sequencing microbiome studies - with the long-term goal of providing critical understanding of microbial populations in the lung transplant respiratory tract and its role in BOS, the major impediment to long-term transplant success.