TLR4活化TAP63a诱导细胞凋亡的分子机制

In the pathophysiology of sepsis, the hyper-inflammatory response induced by the over-activation of toll-like receptors (TLRs) elicits the apoptosis of immune cells, resulting in the immune paralysis which is one of the major factors for the death of the sepsis patients during the secondary infection. So it is very significant for the exhausted investigation of the molecular mechanisms of TLR-induced apoptosis. In our previous study, we found that TLR3 induces cell apoptosis via p63 family member TAp63α. In our pre-experiments of this study, we found that LPS binding TLR4 induces the activation of TAp63α, leading to the up-regulation of BH3-only family members Noxa, Puma, and Bim, which results in the cell apoptosis. These studies suggested that TAp63α may play an important role in the induction of apoptosis. Based on the previous studies and pre-experimental results, we plan to fully elucidate the molecular mechanisms of TLR4-induced cell apoptosis via TAp63α by use of cellular biological and molecular biological methods, and immunologic methods. And try to analyze the effect of TLR4 signaling block by inhibition of TAp63α on cell apoptosis. Furthermore, the effect of TLR4 signaling block by TAp63α inhibition on the pathophysiology of sepsis will be measured in in vivo studies. Our goal is to provide new thoughts for the clinical prevention and treatment of sepsis.

脓毒症的病理生理过程中，活化Toll样受体(TLRs)诱导的过激炎症反应导致免疫细胞凋亡，引发的免疫麻痹状态，是再次感染引起宿主死亡的主要原因之一，因此充分研究TLRs诱导凋亡的分子机制具有重要意义。我们的前期研究发现TLR3通过上调p63家族中的TAp63α介导细胞损伤。本项目的预实验结果显示：LPS作用TLR4诱导TAp63α的活化，上调促凋亡分子BH3-only家族中的Noxa、Puma和Bim介导细胞凋亡，提示TAp63α在TLR4诱导的细胞凋亡过程中发挥重要作用。在前期研究和预实验的基础上，本项目通过采用细胞生物学、分子生物学和免疫学等方法来阐明TLR4活化TAp63α调控细胞凋亡的分子机制；尝试以TAp63α为靶点，分析阻断TLR4信号传导对细胞凋亡的影响；并进一步在体内验证以TAp63为靶点阻断TLR4信号传导对脓毒症发生发展的影响，为临床干预脓毒症提供新的思路。

脓毒症的发生过程中，活化Toll 样受体(TLRs)诱导的过激炎症反应导致免疫细胞凋亡，引发的免疫麻痹状态，是再次感染引起宿主死亡的主要原因之一，因此，本项目主要研究TLRs诱导单核细胞凋亡的分子机制，以期为临床干预脓毒症提供新的思路。本研究发现： LPS作用THP1后，其下游的信号分子ERK, JNK, P38 和 NF-κB P65分子被活化而且细胞因子IL-1α、IL-1β、IL-8和TNFα表达量升高，说明单核细胞THP1可以表达功能性的TLR4蛋白；LPS诱导THP1后，引起时间和剂量依赖性的细胞凋亡，中和实验发现内外源性凋亡途径均参与其中；进一步发现，LPS诱导THP1细胞凋亡中TAp63α发生了核移位，由胞浆进入胞核发挥作用，诱导细胞凋亡，在此起重要作用。此研究为脓毒症的预防和治疗提供了新的靶点。