NF-κB和NADPH氧化酶相互调节介导脓毒症免疫状况转换的机制研究

The mechanism of immunosuppression is one of the hottest topic in sepsis fields, but little is known regarding the mechanism of transition between hyper-inflammatory responses and immunosuppressive state during the process of sepsis. NF-κB activity is critical for controlling inflammation and thus contributes to be a regulator of immune state, NADPH oxidase in phagocytic cells play a key role in host defense. They mutually regulate the activity of each other. Changes in bacterial loads lead to the immune status’s transformation. Hence, we hypothesis that during the process of sepsis, NF-κB and NADPH oxidase can sense the changes of bacterial loads and then regulate the other’s activity, and finally achieve the transition of high inflammatory response to immunosuppression in the host. Based on our previous findings, different severities of CLP can lead to different phenotypes of the immune state in septic mice. Moderate CLP and severe CLP successfully reproduced the hyper-inflammation and immunoisuppression state in septic mice, respectively. In this study, Pseudomonas aeruginosa was administered in different bacterial loads through intratrachael injection for moderate CLP mice and to clarify whether the increased bacterial load can cause the transition of hyper-inflammation to immunosuppression, and to investigate whether the dynamic activity of NF-κB and NADPH oxidase is involved during this process. Furthermore, by using siRNA, co-immunoprecipitation and chromatin co-immunoprecipitation technique, the dynamic changes between NF-κB and NADPH oxidase are explored to interpret their roles in regulating the transition of hyper-inflammation and immunosuppression caused by increased bacterial load. This study will elucidate the possible mechanism of transition between hyper-inflammatory response and immune suppression during sepsis, and might provide the theoretical basis for the future targeted-therapy.

免疫抑制是脓毒症领域的研究热点，但脓毒症高炎症反应向免疫抑制转换的机制尚不清。研究显示NF-κB是炎症控制的中心环节，NADPH氧化酶是吞噬细胞发挥宿主防御功能的关键因素，二者存在相互调节关系；细菌载量变化参与了宿主免疫状态调节。据此我们假说：脓毒症过程中，NF-κB和NADPH氧化酶可感受细菌载量的变化，相互调节对方活性，并由此实现高炎症反应向免疫抑制转换。前期我们通过对中、重度CLP小鼠的表型研究发现它们可分别模拟高炎症反应和免疫抑制状态。本课题利用中度CLP小鼠肺部感染铜绿假单胞菌，阐述菌量增加对免疫状况的调节作用，观察体内NF-κB、NADPH氧化酶活性的动态变化；利用siRNA、IP及ChIP等技术阐述NF-κB和NADPH氧化酶之间如何动态调节以实现宏观水平的免疫状态转换。此研究的开展将阐明脓毒症过程中高炎症反应向免疫抑制转换的机制，并为将来有针对性的靶点治疗提供理论依据。