NR4A1调控巨噬细胞糖代谢重编程在脓毒症中的作用及分子机制研究

Immune dysfunction is an important pathogenic mechanism in sepsis. The glucose metabolic reprogramming of macrophages plays a key role in the imbalance of immune inflammatory response in sepsis. NR4A1 is a member of the orphan nuclear receptor family, and involved in the regulation of macrophage gene expression and inflammatory response. Our preliminary study had shown that NR4A1 expression was increased, oxidative phosphorylation was decreased while glycolysis was increased in the wide-type primary peritoneal macrophages after stimulation with lipopolysaccharide (LPS). However, LPS induced an increased oxidative phosphorylation and unchanged glycolysis in the primary peritoneal macrophages after interfering with NR4A1 expression. In addition, studies have demonstrated that hypoxia induced factor-1α (HIF-1α) is a key molecule in the glucose metabolic reprogamming of macrophages, and NR4A1 can increase HIF-1α protein expression level. Therefore, we hypothesize that NR4A1 may affect the glucose metabolic reprogamming of macrophages via regulating HIF-1α in the occurrence and development of sepsis. The present project will apply kinds of molecular biological skills (transfection of adenovirus vector, et al.) to verify this hypothesis. The project would provide new ideas and targets in the prevention and management of sepsis.

免疫功能紊乱是脓毒症的重要发病机制，巨噬细胞糖代谢重编程在脓毒症免疫炎症反应失衡中发挥关键作用。NR4A1系孤儿核受体家族成员之一，参与巨噬细胞基因转录的调控和炎症反应。我们的预实验发现：脂多糖（LPS）刺激野生型小鼠原代腹腔巨噬细胞NR4A1表达升高，氧化磷酸化降低，糖酵解增加；而干预NR4A1基因表达后，LPS则诱导腹腔巨噬细胞氧化磷酸化增加，糖酵解未发生明显改变。基于低氧诱导因子-1α（HIF-1α）是巨噬细胞糖代谢重编程的关键分子，NR4A1能增加HIF-1α蛋白表达水平，因此我们推测巨噬细胞NR4A1可能通过调控HIF-1α影响巨噬细胞糖代谢重编程，参与脓毒症的发生发展。本项目拟采用基因敲除动物模型、腺病毒载体转染等技术平台，从整体、细胞、分子水平上明确上述假说。本研究将为脓毒症防治探索新的靶标及开辟脓毒症免疫代谢治疗新策略奠定理论基础。

脓毒症是病原微生物入侵机体后触发的异常免疫炎症反应，合并出现危及生命的组织器官功能障碍。巨噬细胞是机体免疫功能的重要始动者和执行者，在炎症反应的发生、发展、转归中发挥重要作用。本项目围绕“NR4A1调控巨噬细胞糖代谢重编程在脓毒症中的作用及机制”，明确了在盲肠结扎穿孔（CLP）致脓毒症模型中巨噬细胞糖酵解增加，氧化磷酸化减少，并证实CLP造模后NR4A1基因敲除小鼠的巨噬细胞代谢转换受到抑制，促炎反应加剧（IL-1beta和IL-6表达较对照组更高，IL-10表达较对照组更低），病死率增加；通过构建骨髓嵌合体模型，进一步证实髓系NR4A1基因参与脓毒症巨噬细胞糖代谢重编程和炎症反应，在CLP致脓毒症中发挥保护作用。此外，该项目还初步阐明了NR4A1调控脓毒症时巨噬细胞糖代谢重编程可能是通过PFKFB3而非HIF-1α。研究工作为进一步了解脓毒症中巨噬细胞代谢状态与炎症反应的关系提供了新视角，并为今后开展临床转化和应用研究提供了发展方向和理论依据，NR4A1也有望成为今后研发脓毒症特异性治疗药物的新靶点。