调节性T细胞影响中性粒细胞迁移参与腹腔感染天然免疫反应调节的机制研究

Abdominal sepsis is associated with significant morbidity and mortality rates. In its pathogenesis, Regulatory T cells (Tregs) undoubtedly play a pivotal role. However, it is still unknown whether Tregs may engage in the regulation of innate immune response during intraabdominal infections. Our preliminary data showed that the number of Tregs obtained from greater omentum increased significantly after cecum ligation and puncture procedure (CLP)，and depletion of Tregs strengthened the migration of neutrophils into the peritoneal cavity of CLP mice. Based on the above reasons, we proposed that, after the onset of intraabdominal infection, Tregs will accumulate into the milky spots of greater omentum and regulate the innate immune response via modulation of the migration of neutrophils. Then in the present study, we will firstly investigate the number and functional alterations of Tregs in milky spots and neutrophils in the peritoneal cavity, and to demonstrate the regulatory role of Tregs on neutrophils migration in milky spots via blocking antibodies. Next, we evaluate the influences of Tregs on neutrophils migration and the septic pathophysiology by modulating the quantity or function of Tregs via blocking antibody, depleting antibody or adoptive transfusion. Then, we will investigate the role of TLR4 signaling in the regulatory effect of Tregs on neutrophils migration and the septic pathophysiology by using co-culture experiments of Tregs with neutrophils and by establishment of Tregs conditional TLR4 knock-out mice. Finally, we will set out to collect patients sample and medical records to discuss the clinical significance and the relationship of alterations of Tregs and neutrophils in patients with intraabdominal infection. To summarize, the implementation of the present proposal will provide important information for further illustrating the pathophysiological mechanism and potential therapeutic targets for the intraabdominal infection with septic complications.

腹腔感染（IAI）合并脓毒症是临床经常面对的棘手问题，调节性T细胞（Treg）变化是其病生理机制的重要环节，但尚不清楚Treg是否参与IAI天然免疫反应调节。前期发现IAI时大网膜乳斑Treg比例上调，而去除Treg后腹腔中性粒细胞（PMN）数量增加，据此提出：IAI后Treg进入大网膜乳斑，影响PMN迁移，调节IAI天然免疫反应。为此，拟首先分析IAI后大网膜乳斑Treg和腹腔PMN等变化，结合阻断抗体，证实Treg进入乳斑影响PMN迁移；通过抗体清除或阻断，Treg过继转输等，分析Treg数量/功能变化对PMN迁移及IAI病生理过程的影响；采用体外共培养和Treg条件性TLR4敲除小鼠，证实Treg受TLR4调控影响PMN迁移调节IAI天然免疫反应；进而，收集IAI患者资料，分析Treg与PMN等变化及其临床意义。藉此深化对IAI病生理机制的认识，为IAI和脓毒症的防治提供参考和依据。

腹腔感染（IAI）合并脓毒症是临床经常面对的棘手问题，调节性T细胞（Treg）变化是其病生理机制的重要环节，但尚不清楚Treg是否参与IAI天然免疫反应调节。课题组从多个角度对该问题进行深入研究，具体如下：1.调节性T细胞活动中白细胞介素-3 的自分泌调节及其在脓毒症病理生理中的作用；2. 腹腔内脓毒症时大网膜在腹膜防御机制中的重要作用；3. 内质网应激及其 PERK 通路可增强TCR诱导的调节性 T 细胞活化；4. a7烟碱型乙酰胆碱受体激动剂GTS-21通过调节单核细胞募集和活性改善混合微生物感染性腹膜炎的细菌清除。项目从不同方向，多个层次证明调节性T细胞抑制中性粒细胞的作用机制，发现脓毒症中调节性T细胞通过自分泌IL-3维持免疫抑制效应，同时该过程中内质网应激及其 PERK 通路发挥重要作用，抑制腹腔大网膜上的中性粒细胞功能。与此同时，单核细胞也在脓毒症细菌清除中发挥积极作用。本项目共发表论文5篇，其中SCI4篇，中华系列杂志1篇。