p38MAP kinase-dependent mechanisms of fever-enhanced acute lung injury

描述（由申请人提供）：这是一份竞争性续期申请，旨在扩展联合首席研究员正在进行的研究，该研究的重点是发烧和退烧对急性肺损伤（ALI）的影响。尽管普遍接受低潮气量通气来支持ALI患者，但此类患者的死亡率仍高达40%。我们确定发热/高热是ARDS发病机制的另一个潜在重要因素。据报道，重症监护病房收治的患者中约有一半出现发热，而ALI/ARDS患者中高达90%出现发热。ARDS的特征是中性粒细胞丰富的炎症，内皮屏障的丧失和上皮损伤。我们之前的研究表明，暴露于发热范围（FRH, ~39.5℃）的高温会大大增加这些致病过程。目前的申请提出了一项机制研究，重点关注p38丝裂原活化蛋白激酶（MAPK）依赖性机制在FRH增强ALI中的作用。我们已经表明，暴露于FRH增强先天免疫功能部分是通过增强中性粒细胞（PMN）募集。这种作用加速了病原体的清除，但也增加了侧支组织的损伤，特别是在肺部。基于新的数据，本研究将重点关注肺血管内皮和应激激活的MAPK， p38的核心作用。初步数据表明：(1)FRH至少部分通过自磷酸化直接激活p38； (2) FRH直接改变p38构象、激酶活性、细胞定位和底物选择性。这一提议将检验以下假设：

DESCRIPTION (provided by applicant): This is a competitive renewal application to extend ongoing research by the co-Principal Investigators that is focused on the effects of fever and fever suppression on acute lung injury (ALI). Despite the general acceptance of low tidal volume ventilation for support of patients with ALI, mortality in such patients remains ~40%. We identified fever/hyperthermia as another potentially important contributor to ARDS pathogenesis. Fever is reported to occur in about half of patients admitted to intensive care units and in up to 90% of those with ALI/ARDS. ARDS is characterized by neutrophil-rich inflammation, loss of endothelial barrier, and epithelial injury. Our previous studies show that exposure to hyperthermia in the febrile range (FRH, ~39.5oC) profoundly augments each of these pathogenic processes. The current application proposes a mechanistic study that focuses on the role of p38 mitogen-activated protein kinase (MAPK)-dependent mechanisms of FRH- augmented ALI. We have shown that exposure to FRH augments innate immune function in part by enhancing neutrophil (PMN) recruitment. This effect accelerates pathogen clearance, but also increases collateral tissue injury, especially in the lung. Based on new data, this proposal focuses on the central role of pulmonary vascular endothelium and the stress-activated MAPK, p38. Preliminary data suggests that (1) FRH directly activates p38 at least in part through autophosphorylation and (2) that FRH directly alters p38 conformation, kinase activity, cellular localization, and substrate selectivity. This proposal will test the following hypotheses: (1) FRH activates p38 through multiple pathways including through a conformational change in p38 that facilitates its autophosphorylation and by activating upstream kinases; (2) the FRH-induced conformational changes in p38 will result in distinct patterns of p38 intermolecular docking, subcellular distribution, and downstream signaling events, which will uniquely modify downstream substrate phosphorylation patterns with important consequences for lung inflammation and injury; and (3) in the patient with ALI and fever, inhibition of p38 or downstream signaling pathways will improve outcome better than suppressing fever. We will use primary cultured HMVEC- Ls and mouse models of ALI to: (1) elucidate the molecular mechanisms by which FRH activates p38, (2) analyze how FRH modifies p38 subcellular distribution and substrate phosphorylation profile, and (3) test the potential of p38 signaling pathway blockade to reduce FRH-augmented lung injury without impairing pathogen clearance. We expect that the results of these studies will clarify the mechanisms of FRH-induced p38 signaling relevant to ALI and provide essential information about disproportionate substrate phosphorylation that will identify alternative therapeutic targets to test in ALI/ARDS. We expect that these findings will have wider applications in mitigating inflammation and injury in other tissues as well.