Mechanisms of Fever-Enhanced Hyperoxic Lung Injury

描述（由申请人提供）：我们发现，暴露于发热范围高温（FRH）通过增加肺内嗜中性粒细胞（PMN）的蓄积，显著加速肺氧中毒的发作和进展。 FRH激活G-CSF表达，扩大循环PMN库，增强跨内皮迁移，并增加高氧肺内CXC趋化因子KC和LIX的产生。 初步数据表明，热休克反应，通常被认为是保护应激细胞，有助于增加肺损伤的高温，高氧肺。 我们推测，FRH和高氧的会聚导致早期和广泛的肺损伤，部分介导的过程中，没有激活的刺激单独。 我们将使用我们的高氧暴露，温度控制的小鼠模型和小鼠和人类细胞培养系统，以阐明FRH和高氧之间的协同作用，导致肺损伤的机制。 具体而言，我们将： 1)确定FRH如何扩大和启动循环PMN池，（第1-4年）：确定过热小鼠中过量G-CSF的来源，并阐明其表达增加的分子机制;分析PMN去边缘化、粒细胞生成增加和PMN存活延长的贡献;并确定FRH是否启动循环PMN的募集和细胞毒性。 2)阐明FRH增加PMN向高氧肺内输送和改变PMN分布的机制（1-4岁）：确定KC和LIX的细胞来源，阐明其表达增加和PMN向肺组织再分布的分子机制;确定FRH是否抑制PMN凋亡，增加PMN坏死和细胞毒性颗粒释放。 3)确定高温、高氧肺中热休克的激活如何反常地导致肺损伤（2-5年）：确定PMN内细胞内热休克蛋白（HSP）的产生是否有助于从PMN凋亡到坏死的转变;以及从受损细胞释放的细胞外HSP-60或-70是否通过其TLR 4依赖性促炎作用增强肺损伤。拟议的研究将为重症患者发烧的意外后果提供新的见解，并扩大我们对发烧改变免疫反应机制的了解。

DESCRIPTION (provided by applicant): We showed that exposure to febrile range hyperthermia (FRH) markedly accelerates onset and progression of pulmonary oxygen toxicity by augmenting accumulation of neutrophils (PMN) within lung interstitium. FRH activates G-CSF expression, expands the circulating PMN pool, enhances transendothelial migration, and augments generation of the CXC chemokines, KC and LIX, within the hyperoxic lung. Preliminary data suggest that the heat shock response, usually thought to be protective in stressed cells, contributes to the augmented lung injury in the hyperthermic, hyperoxic lung. We hypothesize that the convergence of FRH and hyperoxia causes early and extensive lung injury mediated, in part, by processes that are not activated by either stimulus alone. We will use our hyperoxia-exposed, temperature-controlled mouse model and mouse and human cell culture systems to elucidate the mechanisms underlying the synergism between FRH and hyperoxia in causing lung injury. Specifically, we will: 1) Determine how FRH expands and primes the circulating PMN pool, (years 1-4): identify the source of excess G-CSF in hyperthermic mice and elucidate the molecular mechanisms of its increased expression; analyze the contributions of PMN demargination, increased granulopoiesis, and prolonged PMN survival; and determine whether FRH primes circulating PMN for recruitment and cytotoxicity. 2) Elucidate the mechanisms through which FRH augments PMN delivery to and alters PMN distribution within the hyperoxic lung (years 1-4): identify cellular sources of KC and LIX and elucidate the molecular mechanisms of their increased expression and of the redistribution of PMN to lung interstitium; and determine if FRH inhibits PMN apoptosis, and increases PMN necrosis and cytotoxic granule release. 3) Determine how activation of heat shock in the hyperthermic, hyperoxic lung paradoxically worsens lung injury (years 2-5): determine if generation of intracellular heat shock proteins (HSP) within PMN contribute to shift from PMN apoptosis to necrosis; and whether extracellular HSP-60 or -70 released from injured cells augments lung injury through their TLR4-dependent proinflammatory actions. The proposed studies will provide new insights about the unanticipated consequences of fever in critically ill patients, and expand our knowledge about the mechanisms through which fever modifies the immune response.