抗趋化因子CXCL4单克隆抗体防治化疗相关性腹泻的药理机制研究

Chemotherapy induced diarrhea (CID) is a common dose-limiting severe toxicity of cancer chemotherapy. Current drugs manage mild diarrhea symptoms only, which can not protect intestinal epithelial cells from chemotherapy damages. Our previous works have demonstrated that the serum and intestinal mucose local level of chemokine CXCL4 was highly elevated by chemotherapy. Use of CXCL4 neutralizing antibody effectively suppressed 5-FU induced expression of p53 and Bax in epithelial cells, reduced apopotosis of the cells, and decreased the incidense and severity of CID in mice. In this application, firstly, we will establish the relationship of CXCL4 expression changes to the cause, course, and severity of CID, identify the target cells of CXCL4 which are the cells expressing the CXCL4 receptor CXCR3; Using the intestinal epithelial cell line (IEC-6) the CXCR3 signaling pathways will be identified specific to the activation by CXCL4.The mechanisms of CXCL4 induced apoptosis of epithelial cells will also be evaluated. Finally,using CID mouse model, the pharmacodynamics and pharmacology of anti-CXCL4 mAb will be carried out to provide data for the antibody drug development.We have developed complete reserch system and established great research condition which will insure the completeness of this applied study.

化疗相关性腹泻（CID）是肿瘤化疗常见剂量限制性严重毒性反应。已有药物仅对轻度CID症状有缓解，无法从根本上防治CID肠道粘膜损伤。我们前期工作证实：化疗导致血清和肠粘膜局部趋化因子CXCL4水平显著升高；给化疗小鼠注射抗CXCL4中和抗体，能显著抑制化疗对肠粘膜细胞p53和Bax基因表达的上调，有效减轻上皮细胞凋亡，降低CID发病率和严重程度。本项目将首先揭示CXCL4表达变化与CID病因、病程、以及严重程度之间的关系，确定CXCL4在肠粘膜中的靶细胞，即其受体CXCR3表达的细胞；用肠粘膜上皮细胞（IEC-6）体外实验研究CXCL4激活CXCR3受体、确认其下游信号通路以及诱导细胞凋亡的靶基因；最后，利用小鼠CID模型，开展抗CXCL4 单克隆抗体防治CID的药效药理机制研究，为CXCL4单抗药物研发提供依据。已建立完善的研究体系和良好的科研条件，为课题完成奠定坚实基础。

化疗相关性腹泻（CID）是肿瘤化疗常见剂量限制性毒性反应，严重时可导致病人休克甚至死亡。目前临床尚无预防CID的药物，已有治疗性药物通过抑制肠蠕动仅对轻度CID症状有缓解作用，不能从根本上预防化疗对肠黏膜上皮细胞的损伤。本基金项目研究表明，化疗导致血清和肠粘膜局部趋化因子CXCL4水平显著升高, 给化疗小鼠注射抗CXCL4中和抗体能有效减轻5-FU 导致的肠黏膜损伤程度，大大降低腹泻发生率、严重程度和缩短腹泻持续时间，减轻体重降低和加速体重恢复，并且显著地提高了小鼠存活率。.本基金项目还进一步通过体内和体外实验深入研究了抗CXCL4中和抗体防治CID 的药理机制。结果表明化疗诱导的CXCL4水平升高并与其受体CXCR3结合启动下游信号通路，激活p38信号通路，上调p53和Bax的表达，最终激活caspases，导致肠粘膜上皮细胞凋亡进而诱导化疗行腹泻的发生。抗CXCL4中和抗体通过与CXCL4结合阻断这一通路过程，抑制p53和Bax的表达上调，减少肠粘膜上皮细胞的凋亡。.本基金项目证实了抗CXCL4中和抗体对CID 全面的、稳定的防治疗效，减少化疗导致的小鼠肠黏膜损伤，加速肠黏膜再生修复，最终实现防治CID，为临床CID 的防治提供了新的预防策略，也为抗CXCL4中和抗体开发成预防CID的一类新药奠定坚实的临床前研究基础。