Cholinergic anti-inflammatory mechanisms in sepsis and septic shock

描述(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、全身性炎症反应综合征、感染性休克和多器官功能障碍综合征(MODS)。为败血症/感染性休克和多器官功能障碍综合征开发有效的治疗方法已被证明是极其困难的。我们假设脓毒症的全身炎症反应可以通过使用α7尼古丁受体激动剂来激活胆碱能抗炎途径来减弱或中止。这条途径是反射弧线的一部分，通过作用于脾来抑制巨噬细胞产生促炎细胞因子来调节免疫反应。该通路的神经成分包括支配脾的节前迷走神经(胆碱能)及其靶交感神经元(去甲肾上腺素能)。最近的证据表明，去甲肾上腺素的局部释放激活了脾T细胞中的胆碱能表型，但在脾中胆碱能标志物的原位表达尚未被探索。巨噬细胞产生细胞因子的抑制是由α7烟碱受体介导的。激活的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，并可能是ACh的另一个来源。此外，脾单核细胞也产生炎性细胞因子，并可能成为ACh的额外靶点。因此，关于将神经信号转换为抗炎/抗败血症反应的机制有许多未知之处。有证据表明，胆碱能抗炎途径的益处似乎超出了脾，但全身反应的全面程度尚未确定，这一证据放大了其临床意义。该项目将通过使用临床相关的多菌败血症(CLP)小鼠模型来解决这些知识差距，并评估通过刺激α7尼古丁受体激活胆碱能抗炎途径的药物(GTS-21)治疗引起的组织化学、生化和治疗反应。目的1)应用生化和免疫组织化学方法：1)鉴定和鉴定产生和/或应答ACh的脾细胞；2)评价GTS-21增加脾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治疗的反应。将使用不同的给药方案来评估GTS-21在预防、减轻或逆转脓毒症引起的心功能障碍、肺病理和免疫抑制方面的效果。这项研究的结果将扩大我们对胆碱能抗炎途径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.