Cholinergic anti-inflammatory mechanisms in sepsis and septic shock

描述（由申请人提供）：危重患者经常出现复杂的疾病谱，可能包括急性呼吸窘迫综合征、全身炎症反应综合征、感染性休克和多器官功能障碍综合征（MODS）。已经证明，开发针对脓毒症/脓毒性休克和MODS的有效疗法的尝试极其困难。我们假设，通过使用α 7烟碱受体激动剂激活胆碱能抗炎通路，可以减弱或中止对脓毒症的全身炎症反应。该途径是反射弧的一部分，反射弧通过作用于脾脏以抑制巨噬细胞产生促炎细胞因子来调节免疫应答。该通路的神经成分包括支配脾脏的节前迷走传出神经（胆碱能）及其靶向节后交感神经元（去甲肾上腺素能）。最近的证据表明，局部释放的去甲肾上腺素激活胆碱能表型在脾T细胞，但在原位表达的胆碱能标记物在脾还没有被探讨。巨噬细胞产生细胞因子的抑制由α 7烟碱受体介导。活化的T细胞可能是刺激这些受体的乙酰胆碱（ACh）的来源。然而，巨噬细胞也可以获得胆碱能表型，可能是乙酰胆碱的额外来源。此外，脾单核细胞也产生炎性细胞因子，可能是ACh的额外靶点。因此，关于将神经信号转化为抗炎/抗败血症反应的机制存在许多未知数。胆碱能抗炎通路的临床意义被证据放大，其益处似乎超出了脾脏，但全身反应的全部程度尚未确定。该项目将通过使用临床相关的多微生物脓毒症（CLP）小鼠模型，并评估通过刺激α 7烟碱受体激活胆碱能抗炎通路的药物（GTS-21）治疗引起的组织化学，生物化学和治疗反应来解决这些知识空白。目的1将采用生物化学和免疫组织化学方法：1）鉴定和表征产生和/或响应ACh的脾细胞，2）评价GTS-21增加脾中ACh浓度和抑制脾细胞产生炎性细胞因子的作用。目的2将评估脓毒症小鼠对GTS-21治疗的治疗反应。将使用不同的给药方案来评价GTS-21在预防、减轻或逆转脓毒症诱导的心功能障碍、肺病理学和免疫抑制方面的疗效。这项研究的结果将扩大我们对胆碱能抗炎通路的机制和治疗潜力的理解。

DESCRIPTION (provided by applicant): The critically ill patient frequently develops a complex disease spectrum that may include acute respiratory distress syndrome, systemic inflammatory response syndrome, septic shock and multiple organ dysfunction syndrome (MODS). Attempts at developing effective therapies for sepsis/septic shock and MODS have proven to be exceedingly difficult. We hypothesize that the systemic inflammatory response to sepsis can be attenuated or aborted by using an alpha7 nicotinic receptor agonist to activate the cholinergic anti- inflammatory pathway. This pathway is part of a reflex arc that modulates immune responses by acting at the spleen to suppress production of pro-inflammatory cytokines by macrophages. The neural components of this pathway comprise preganglionic vagal efferent nerves (cholinergic) and their target postganglionic sympathetic neurons (noradrenergic) that innervate the spleen. Recent evidence suggests that local release of norepinephrine activates a cholinergic phenotype in splenic T cells, but in situ expression of cholinergic markers in the spleen has not been explored. Suppression of cytokine production by macrophages is mediated by alpha7 nicotinic receptors. Activated T cells may be the source of acetylcholine (ACh) that stimulates these receptors. However, macrophages can also acquire a cholinergic phenotype and might be an additional source for ACh. Furthermore, splenic monocytes also produce inflammatory cytokines and could be additional targets for ACh. Thus, there are many unknowns regarding mechanisms involved in converting the neural signal into an anti-inflammatory/anti-sepsis response. The clinical significance of the cholinergic anti-inflammatory pathway is amplified by evidence that its benefits appear to reach beyond the spleen, but the full extent of the systemic response is yet to be established. This project will address these gaps in knowledge by using a clinically relevant murine model of polymicrobial sepsis (CLP) and evaluating histochemical, biochemical, and therapeutic responses evoked by treatment with a drug (GTS-21) that activates the cholinergic anti-inflammatory pathway by stimulation of alpha7 nicotinic receptors. Aim 1 will employ biochemical and immunohistochemical methods to: 1) identify and characterize splenocytes that make and/or respond to ACh and 2) evaluate effects of GTS-21 to increase ACh concentration in the spleen and suppress production of inflammatory cytokines by splenocytes. Aim 2 will evaluate the therapeutic response of septic mice to treatment with GTS-21. Different dosing regimens will be used to evaluate the efficacy of GTS-21 at preventing, attenuating, or reversing sepsis-induced cardiac dysfunction, pulmonary pathology, and immunosuppression. Results from this study will expand our understanding of the mechanisms and therapeutic potential of the cholinergic anti-inflammatory pathway.