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

这个卓越研究（EiR）项目旨在通过解决中心研究问题来加强STEM研究，“为什么我们的免疫系统进化到用炎症来治疗微生物危险和细胞损伤？”。在非无菌环境中，当存在潜在的有害细菌时，穿透性创伤会导致炎症。类似地，当生物体的细胞/组织受伤/受损时，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，但这些创伤后的炎症现象惊人地相似。该项目将重点关注线粒体，特别是线粒体肽和核酸，作为无菌炎症的介质。本项目将研究肌肉收缩诱导损伤（CII）后无菌性炎症的机制，这将填补运动生理学的知识空白。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，增加STEM管道中下一代人才的保留。与此同时，这项研究的追求将提高一个历史悠久的黑人学院大学（HBCU）的机构研究能力。免疫系统既可以治疗微生物的危险，也可以治疗炎症引起的细胞损伤。当存在潜在有害细菌时，在非无菌环境中的穿透性创伤之后会发生炎症，并且当生物体的细胞/组织由于无菌条件下的非穿透性创伤而受伤/受损时，炎症可能会发生。目前，科学家们了解到，来自线粒体（mtDAMP）的损伤相关分子模式在创伤患者中升高，并且mtDAMP在无菌炎症中发挥因果作用。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。特定的分子特征，如N-甲酰肽（mtFP），已被牵连，但其他可能性存在，包括未甲基化的胞嘧啶-磷酸-鸟嘌呤（CpG）DNA重复序列的模式，和环状的性质，线粒体DNA。研究人员假设，运动过程中肌肉收缩引起的损伤会导致mtDAMP的释放，从而激活先天免疫，导致运动员的无菌炎症。特别是，研究人员将测量运动诱导的无菌性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，以查询骨骼肌细胞和先天免疫细胞（如单核细胞和中性粒细胞）的体外相互作用。本文研究了人线粒体腺苷二磷酸酶亚基6（ND 6）的结构和热力学性质。研究人员将使用多种方法，如ELISA研究线粒体蛋白，PCR研究线粒体核酸，X射线晶体学研究ND 6的结构。这项研究将阐明临床非感染性创伤和单纯剧烈运动引起的创伤之间的相似性。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值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.