Transduction of Psychological Stress into Systematic Inflammation by Mitochondrial DNA Signaling

项目概要 据信，全身炎症会导致心理压力对健康造成损害。在 在实验室环境中，一次急性的社会评价压力会导致亲评价延迟升高。 健康成人的炎症细胞因子。然而，心理压力的生物学机制 转化为炎症的机制尚不清楚。已知会造成压力的细胞成分 信号传导是线粒体——一种细菌衍生的细胞器，有自己的基因组，即线粒体 DNA （线粒体DNA）。最近的证据表明，各种压力源会诱导线粒体的释放 衍生的信号分子或线粒体因子。线粒体因子全身移动并调节中枢生理 过程，包括免疫细胞功能和促炎细胞因子的产生。一键线粒体因子 是循环游离细胞 mtDNA (ccf-mtDNA)，它是由 mtDNA 的线粒体挤出产生的，被认为是 由 Toll 样受体 9 (TLR-9) 作用，导致动物和人类产生促炎细胞因子 细胞。我们的初步数据表明，ccf-mtDNA 释放，而非 ccf-核 DNA，是被急剧诱导的 在对人类进行短暂的心理压力实验后。因此，我们认为ccf-mtDNA可能是 压力-炎症级联中缺失的环节。与此同时，细胞系统的成像和分子研究 表明 ccf-mtDNA 可能由初级神经内分泌应激介质快速诱导，包括 糖皮质激素。该提案将使用实验性社会评价压力任务，并与 控制每个参与者的无压力访问，以绘制 ccf-mtDNA 的反应和恢复动力学， 健康女性和男性的其他压力调节因素。目标 1 将确定： i) ccf-的大小和动力学 线粒体DNA释放； ii) 与核 DNA 相比，该反应的特异性； iii) 检查潜在的性别 这个过程中的差异； iv) 统计测试ccf-mtDNA作为随后pro-增加的中介 炎症细胞因子。在目标 2 中，细胞和分子研究将确定： i) 是否是原发性的 糖皮质激素和儿茶酚胺应激激素足以在原发性中触发ccf-mtDNA释放 人类培养细胞和分离的白细胞； ii) 活细胞 mtDNA 因压力而释放的图像 信号发送； iii) 记录有助于 ccf-mtDNA 释放的 mtDNA 结构的物理变化。最后， 目标 3 将建立： i) 来自峰值 ccf-mtDNA 血清的 ccf-mtDNA 激活细胞因子产生的能力 靶细胞； ii) 人血清中ccf-mtDNA的结构形式和可及性（来自目标1）；以及 iii) 免疫激活依赖于 TLR-9。总体而言，这些研究将为以下方面提供机制证据： 将压力转化为人类炎症的新型线粒体介导机制。结果来自 这项工作将确定新的潜在目标，以改善与压力相关的心理健康和炎症性疾病。

PROJECT SUMMARY Systemic inflammation is believed to contribute to the damaging health effects of psychological stress. In the laboratory setting, a single acute bout of socioevaluative stress leads to a delayed elevation of pro- inflammatory cytokines in healthy adults. However, the biological mechanisms by which psychological stress is transduced into inflammation is not well understood. A cellular component known to contribute to stress signaling is the mitochondrion – a bacteria-derived organelle with its own genome, the mitochondrial DNA (mtDNA). Recent evidence has demonstrated that various stressors induce the release of mitochondria- derived signaling molecules, or mitokines. Mitokines travel systemically and modulate central physiological processes, including immune cell function and the production of pro-inflammatory cytokines. One key mitokine is circulating cell-free mtDNA (ccf-mtDNA), which arises from mitochondrial extrusion of mtDNA, is recognized by the toll-like receptor 9 (TLR-9), and leads to pro-inflammatory cytokine production in animal and human cells. Our preliminary data showed that ccf-mtDNA release, but not ccf-nuclear DNA, is acutely induced following a brief experimental psychological stress in humans. Thus, we suggest that ccf-mtDNA may be a missing link in the stress-inflammation cascade. In parallel, imaging and molecular studies on cellular systems suggests that ccf-mtDNA may be rapidly induced by primary neuroendocrine stress mediators, including glucocorticoids. This proposal will use an experimental socio-evaluative stress task, counterbalanced with a control no-stress visit for each participant, to map the kinetics of reactivity and recovery in ccf-mtDNA and other stress mediators in healthy women and men. Aim 1 will establish: i) the magnitude and kinetics of ccf- mtDNA release; ii) the specificity of this response compared to nuclear DNA; iii) examine potential sex differences in this process; and iv) statistically test ccf-mtDNA as a mediator of the subsequent increase in pro- inflammatory cytokines. In Aim 2, cellular and molecular studies will determine: i) whether primary glucocorticoid and catecholamine stress hormones are sufficient to trigger ccf-mtDNA release in primary human cultured cells and isolated leukocytes; ii) image in living cells mtDNA release in response to stress signaling; and iii) document physical changes in mtDNA structure that contribute to ccf-mtDNA release. Finally, Aim 3 will establish: i) the capacity of ccf-mtDNA from peak ccf-mtDNA serum to activate cytokine production in target cells; ii) the structural form and accessibility of ccf-mtDNA in human serum (from Aim 1); and iii) the dependency on TLR-9 for immune activation. Overall, these studies will contribute mechanistic evidence for a novel mitochondria-mediated mechanisms for transducing stress into inflammation in humans. Outcomes from this work will identify new potential targets to improve stress-related mental health and inflammatory disorders.