HMGB1 在重症中暑肠道损伤中作用机制的研究

The high mortality of severe heatstroke (SHS) is dut to the unclear mechanisms that heat stress induces systemic inflammatory response syndrome and multiple organ dysfunction syndrome, so as to no specific treatment is available. Gut-derived endotoxin and pathogenic bacteria have been proposed to be an important causative factor of morbidity and death during heatstroke. Our previous works also found that heat stress induced elevation of intestinal permeability, bacterial translocation and the occurrence of endotoxemia, and that the degree of intestinal inflammatory response and injury was associated with systemic inflammatory response and disease severity, suggesting that intestine may play an important role in SHS. However, the molecular changes underlying heat stress-induced intestinal lesions have not yet been well characterized. High mobility group box 1 (HMGB1) is a key inflammatory factor in sepsis. Our studies also shown that HMGB1 increases obviously in heatstroke patients, and can directly damage intestinal epithelial cells. Based on above knowledgement,in this project the SHS animal model and heat-stressed intestinal epithelial cells will be used. The changes in HMGB1 and the molecules that probably regulating HMGB1 expression and secretion inculuding its receptors (RAGE and TLR-4) and signal molecules (JAK/STAT and p38 MAPK) will be detected. Moreover, HMGB1 knockout animal, RANi technology, intenstinal protection interventions(cooling treatment and anti-inflammatory medicine) will also be used to clarify the regulation mechanisms of HMGB1 expression and secretion to intestinal lesions in SHS from the pros and cons of two-way, so as to provided the experimental basis for reducing SHS mortality.

重症中暑(SHS)是一种高病死率疾病，因其发病机制不清，暂无针对性治疗措施。近期研究显示，SHS是在热打击基础上，继发全身炎症反应综合征，进而致多脏器功能衰竭的过程，而肠源性感染和内毒素血症可能是其发生发展的关键机制。我们前期研究中发现SHS动物存在肠道损伤现象，且肠道局部炎症和损伤程度与全身炎症反应和疾病严重程度密切相关，提示肠道在中暑的发生发展中有重要作用，但其具体分子机制尚不明确。高迁移率族蛋白B1(HMGB1)是脓毒症重要的炎性分子，我们在中暑患者血中也发现HMGB1明显升高，并可直接损伤肠上皮细胞。本项目拟在前期工作基础上，利用动物和细胞模型，围绕HMGB1及可能参与其表达和分泌的RAGE和TLR-4受体、JAK/STAT和p38 MAPK信号通路，通过基因敲除动物、RANi技术及降温和抗炎药物处理，从正反双向研究HMGB1在肠道损伤中的作用机制，为降低SHS病死率提供科学依据。

重症中暑(SHS)是一种高病死率疾病，因其发病机制不清，暂无针对性治疗措施。目前认为SHS是在热打击基础上，继发全身炎症反应综合征，进而致多脏器功能衰竭的过程，而肠源性感染和内毒素血症可能是其发生发展的关键机制。我们前期研究发现SHS动物存在肠道损伤现象，且肠道局部炎症和损伤程度与全身炎症反应和疾病严重程度密切相关，提示肠道在中暑的发生发展中有重要作用，但关于中暑可引起肠道功能障碍的潜在机制尚不清楚，从而限制了开发对应的治疗策略。本项目从多途径基本阐明了中暑热打击下肠道损伤的病变规律和部分分子机制，并同时从开发新的肠道损伤评价指标到针对性的降温治疗措施和药物4-PBA和乌司他丁进行了应用基础研究，具体研究发现包括：1）热打击可诱导肠上皮细胞HMGB1的表达和分泌，并且发现热打击肠上皮细胞损伤早期自噬可能对凋亡有保护作用；2）发现热打击可以通过溶酶体和线粒体依赖途径诱导肠道损伤；3）发现NF-κB可通过调节HSF1和c-jun激活参与了热应激诱导的肠上皮细胞凋亡；4）发现氧化应激调节丝裂原活化蛋白激酶C-Jun活化参与了热应激和脂多糖诱导肠上皮细胞凋亡；5发现肠源性防御素cry-2不仅可能参与肠道损伤，而且肠道和血液中cry-2水平可能作为肠道损伤的分子标记物；6）发现了中暑肠道细胞凋亡的内质网应激机制，并研究了药物4-苯丁酸酯（4-PBA）对中暑肠道损伤的保护作用和分子机制；7）发现针对性的降温措施和多靶点抗炎药物乌司他丁对肠道损伤具有显著的保护作用。这为深入认识中暑肠道损伤机制，开发应用评价分子标记物和针对性治疗提供了基础和备选措施。项目成果包括在SCI 杂志上发表论文10 篇，中文论著2篇，综述2 篇，参加国际和国内学术大会交流获得优秀论文奖5次；培养硕士研究生2名，其中一名获得优秀毕业研究生奖。资助留美博士1名，项目参与获得广东省科技进步二等奖一项。