NLRC3致脓毒症免疫麻痹的代谢及炎症信号机制

Sepsis-induced immunoparalysisis is a leading cause of death for septic patients, but the mechanism remains to be identied. The impaired aerobic glycolysis (Warburg effect) and the downregulated ability of proinflammatory cytokines production are the main features in these patients who encountered immunoparalysis. Our preliminary study showed that the release of TNF-α, the activation of mTOR which is involved in the anaerobic glycolysis were decreased in the immune cells from septic immunoparalysis. At the same time, we found the mRNA expression of NLRC3 was increased which is a pattern recognition receptor related to negatively regulate the host response in monocytes from the hyporeactive septic patients. The NLRC3 could reduce the activity of PI3K p85 itself involved in the activation of mTOR pathway and inhibit the k63-linked polyubiquitination of TRAF6 involved in the activation of NF-κB p65. According these findings we hypothesize that NLRC3 promote immunoparalysis via inhibiting the PI3K-mTOR signaling pathway mediated the Warburg effect and dampening TRAF6 ubiquitination mediated the NF-κB p65 activation in sepsis. We will thus test this hypothesis in present proposal as follow. Aim1, we will observe the change of NLRC3 in human monocytes and mice splenic cells or monocytes/macrophages during the progression of immunoparalysis. Aim2, we are also going to investigate the effects of NLRC3 on the glycolysis and immunoparalysis of sepsis. Aim3, the interaction of NLRC3 and mTOR pathway will be studied, and we will conform that mTOR pathway is a downstream molecular of NLRC3. Aim4, the interaction of NLRC3 and TRAF6 pathway will be investigated, and we will further conform that TRAF6 pathway is a downstream molecular of NLRC3. This research may helpful to further clarify the mechanism of septic immunoparalysis and provide a new molecular target to rescue immunoparalysis.

免疫麻痹是脓毒症死亡的主要原因之一，但机制不明。免疫细胞有氧糖酵解受损、促炎因子分泌能力下降是免疫麻痹的重要特征。我们前期发现免疫麻痹时TNF-α表达、有氧糖酵解调节蛋白mTOR活性降低，单核细胞的负向调控模式识别受体NLRC3表达升高。由于NLRC3可通过结合PI3K来调节mTOR活性及调控TRAF6 K63位泛素化，因此，我们提出研究假设：NLRC3上调造成PI3K-mTOR介导氧糖酵解及TRAF6 K63位泛素化介导的促炎信号受损，从而导致脓毒症免疫麻痹。本项目拟开展以下研究工作：首先，探讨NLRC3在脓毒症免疫麻痹进程中的表达变化。其次，研究NLRC3对脓毒症免疫麻痹及其有氧糖酵解的影响；然后，探讨NLRC3与mTOR信号通路相互作用及关系；最后，探讨NLRC3与TRAF6信号通路相互作用及关系；本研究将有助于深入认识脓毒症免疫麻痹的发生机制，为改善免疫麻痹提供新的分子靶点。

免疫麻痹是脓毒症死亡的主要原因之一，但机制不明。免疫细胞有氧糖酵解受损、促炎因子分泌能力下降是免疫麻痹的重要特征。我们前期发现免疫麻痹时TNF-α表达、有氧糖酵解调节蛋白mTOR活性降低，单核细胞的负向调控模式识别受体NLRC3表达升高。由于NLRC3可通过结合PI3K来调节mTOR活性及调控TRAF6K63位泛素化，因此，我们提出研究假设：NLRC3上调造成PI3K-mTOR介导氧糖酵解及TRAF6K63位泛素化介导的促炎信号受损，从而导致脓毒症免疫麻痹。本项目拟开展以下研究工作：探明脓毒症小鼠腹腔及肺泡巨噬细胞NLRC3在脓毒症模型建立48h后表达显著增加，特异性敲除巨噬细胞NLRC3表达，可改善脓毒症小鼠肺泡巨噬细胞和腹腔巨噬细胞免疫麻痹，提高肺的免疫防御能力，增强脓毒症小鼠遭受二次打击时对细菌的清除能力，提高脓毒症免疫麻痹小鼠的生存率。在机制上，NLRC3通过与mTOR和TRAF6信号通路相互作用，抑制免疫麻痹小鼠巨噬细胞糖酵解活性，下调NLRC3表达，增加mTOR活性和TRAF6泛素化，提高免疫麻痹巨噬细胞糖酵解活性。进一步研究证实，单独抑制mTOR和TRAF6信号通路，并不能显著抑制NLRC3下调改善的巨噬细胞糖酵解活性。本研究将有助于深入认识脓毒症免疫麻痹的发生机制，为改善免疫麻痹提供新的分子靶点。