Excellence in Research: Mitochondrial Damage-Associated Molecular Patterns (mtDAMPs) as Immunostimulants

这一卓越研究(EIR)项目致力于通过解决核心研究问题来加强STEM研究，这一问题是：为什么我们的免疫系统进化到既能治疗微生物的危险，又能用炎症来治疗细胞损伤？在非无菌环境中，当潜在的有害细菌存在时，炎症会伴随着穿透性创伤。同样，当有机体的细胞/组织受到损伤/破坏时，可能是由于非穿透性创伤，无菌炎症随之而来。尽管情况非常不同，但这些创伤例子之后的炎症现象惊人地相似。这个项目将专注于线粒体，特别是线粒体多肽和核酸，作为无菌炎症的媒介。本项目将研究肌肉收缩诱导损伤(CII)后无菌炎症的机制，以填补运动生理学方面的知识空白。这项研究可能会进一步深入了解线粒体进化为内共生体的后果，以及CII的免疫/炎症影响。另一个目标是充分利用该项目来提高研究能力。学生和博士后研究员将在该项目期间接受培训和指导，以留住STEM管道中的下一代人才。与此同时，这项研究的开展将增强一所历史悠久的黑人学院和大学(HBCU)的机构研究能力。免疫系统通过炎症治疗微生物危险和细胞损伤。在非无菌环境中，当存在潜在有害细菌时，炎症会伴随着穿透性创伤而发生，当在无菌条件下，由于非穿透性创伤而导致有机体细胞/组织受到伤害/损害时，可能会发生炎症。目前，科学家了解到来自线粒体的损伤相关分子模式(MtDAMPs)在创伤患者中升高，并且mtDAMPs在无菌炎症中起因果作用。然而，这种增加的机制及其与运动生理学的相关性尚不清楚。已经涉及到特定的分子特征，如N-甲酰肽(Mtfps)，但也存在其他可能性，包括线粒体DNA中未甲基化的胞嘧啶-磷酸-鸟嘌呤(CpG)DNA重复模式和环状性质。研究人员假设，运动过程中肌肉收缩导致的损伤会导致mtDAMPs的释放，从而激活先天免疫，导致运动员出现无菌炎症。特别是，研究人员将测量运动引起的不孕不育炎症中线粒体蛋白质和核酸的水平。研究人员还将开发细胞培养基础设施，以询问骨骼肌细胞和先天性免疫细胞(如单核细胞和中性粒细胞)的体外相互作用。将研究人mtDAMP烟酰胺腺嘌呤二核苷酸脱氢酶亚单位6(ND6)的结构和热力学性质。研究人员将使用多种方法，如研究线粒体蛋白质的酶联免疫吸附试验，研究线粒体核酸的聚合酶链式反应，以及X射线结晶学来阐明ND6的结构。这项研究将阐明临床非感染性创伤和单纯由剧烈运动引起的创伤之间的相似之处。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This Excellence in Research (EiR) project aspires to enhance STEM research by tackling the central research question, “Why did our immune systems evolve to treat both microbial danger and cellular damage with inflammation?”. Inflammation follows penetrative trauma, in non-sterile settings, when potentially harmful bacteria are present. Similarly, when an organism’s cells/tissues are injured/damaged, perhaps due to non-penetrative trauma, sterile inflammation follows. Despite the very different circumstances, the inflammatory phenomena following these examples of trauma are surprisingly similar. This project will focus on mitochondria, specifically, mitochondrial peptides and nucleic acids, as mediators of sterile inflammation. The mechanisms of sterile inflammation following muscle contraction-induced injury (CII) that will be studied in this project will fulfill a knowledge gap in exercise physiology. The research may offer further insight into the consequences of mitochondria evolving to be endosymbionts as well as immune/ inflammatory implications of CII. Another objective is to fully leverage the project to enhance research capacity. Students and a postdoctoral fellow will be trained and mentored during this project, increasing retention of the next generation of talent in the STEM pipeline. Meanwhile, pursuit of this research will enhance institutional research capacity at a Historically Black College & University (HBCU).Immune systems treat both microbial danger and cellular damage with inflammation. Inflammation follows penetrative trauma in non-sterile settings, when potentially harmful bacteria are present, and inflammation may follow when an organism’s cells/tissues are injured/damaged due to non-penetrative trauma in sterile conditions. Presently, scientists understand that damage-associated molecular patterns emanating from mitochondria (mtDAMPs) are elevated in trauma patients, and that mtDAMPs play a causal role in sterile inflammation. However, the mechanism underlying this increase and its relevance to exercise physiology is unknown. Specific molecular signatures, such as N-formyl peptides (mtFPs), have been implicated, but other possibilities exist, including the pattern of unmethylated cytosine-phosphate-guanine (CpG) DNA repeats in, and circular nature of, mitochondrial DNA. The investigators hypothesize that muscle contraction-induced injury during exercise causes the release of mtDAMPs, which activate innate immunity, leading to sterile inflammation in athletes. In particular, the investigators will measure the levels of mitochondrial proteins and nucleic acids in exercise-induced sterile inflammation. The investigators will also develop cell culture infrastructure to query in vitro interactions of skeletal muscle cells and innate immune cells, such as monocytes and neutrophils. Structural and thermodynamic properties of the human mtDAMP, nicotinamide adenine dinucleotide dehydrogenase subunit 6 (ND6) will be investigated. The investigators will use a variety of methods, such as ELISA to investigate mitochondrial proteins, PCR to investigate mitochondrial nucleic acids, and x-ray crystallography to elucidate the structure of ND6. This research will shed light on similarities between clinical noninfective trauma and the trauma elicited simply by strenuous exercise.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.