趋化因子受体CXCR2促进腹主动脉瘤发生的病理生理机制研究

Abdominal aortic aneurysm (AAA) is a leading cause of sudden death in aging men. Among the numerous pathophysiologic mechanisms, macrophage-mediated inflammation plays pivotal role in the progression of AAA. Chemokine receptors have distinct role in macrophage biology and inflammatory disease regulation, by controlling macrophage functions including recruitment, activation and polarization. Chemokine receptor plays a critical role in inflammation regulation and is involved in AAA formation. We used microarray analysis to test the mRNA expression alteration in AAA tissue from ApoE-/- mice induced by angiotensin II (Ang II) infusion. The result showed that CXCR2 mRNA expression was significantly upregulated in AAA tissue. To determine whether CXCR2 is involved in the progression of AAA, we used the specific CXCR2 antagonist SB265610 to block the chemokine signalling induced by Ang II in ApoE-/- mice. We have found that blockade of CXCR2 with inhibitor SB265610 could attenuate development of AAA by reducing the local inflammation. However, the underlying mechanisms of how CXCR2 activation could recruit macrophage and control the activation and polarization of macrophage, remain unknown. On the basis of our preliminary experiments, the project intends to solve the undefined problems. We will use the specific inhibitor, gene knockout mice and leukocyte-specific CXCR2-/- chimeric mice to block the activation of CXCR2 in vivo to illustrate the pathophysiological mechanisms of how CXCR2 could promote AAA formation and progression, and to determine whether CXCR2 could promote the recruitment of bone marrow-derived macrophages within the AAA wall at the level of animal model. Furthermore, we will perform single cell culture and co-culture to determine the molecular mechanisms of how CXCR2 could participate in the migration, activation and polarization of macrophages, and of how CXCR2 could participate in the induction of VSMC apoptosis by macrophage. In this way, we aim to reveal the precise pathophysiological and molecular mechanisms of how CXCR2 could promote the AAA progression, to find a potential target for future strategies designed to combat AAA.

趋化因子/受体是介导免疫细胞到组织聚集和活化的关键通路。单核/巨噬细胞聚集是促进腹主动脉瘤（AAA）形成的重要因素，但是调节其聚集和活化的关键趋化因子受体仍不清楚。我们前期研究发现在人AAA组织中和血管紧张素II（Ang II）诱导ApoE-/-小鼠AAA中CXCR2表达明显升高，应用CXCR2拮抗剂SB265610可明显降低ApoE-/-小鼠AAA发生率和严重程度、抑制血管炎症反应和巨噬细胞聚集。但是CXCR2促进AAA形成病理生理机制仍需深入研究。因此，本课题应用Ang II诱导ApoE-/-小鼠AAA模型，采用ApoE-/- CXCR2-/- 双基因敲除鼠、骨髓移植嵌合体鼠、拮抗剂处理及体外细胞共培养，研究CXCR2在AAA形成中的作用及病理生理机制；明确CXCR2对单核/巨噬细胞增殖、活化、极化的调节机制。阐明CXCR2调节AAA形成的病理生理机制，为寻找防治AAA新靶点提供依据。

腹主动脉瘤（AAA）是常见血管疾病，目前尚无有效的监测指标及药物干预靶点。本课题组研究发现包括：1、CXC趋化因子受体2（CXCR2）参与调节AAA形成，主要通过促进单核/巨噬细胞在主动脉组织浸润、活化，促进组织胶原沉积、基质金属蛋白酶活化等。CXCR2特异性拮抗剂SB265610、SB225002可延缓小鼠AAA发生发展；2、采用非靶向代谢组学和转录组学分析AAA与动脉粥样硬化（AS）基因表达差异，筛选出18种差异代谢物，发现7种代谢物，特别是2’-脱氧-D-核糖（2dDR），与差异表达基因显著相关；3、采用生物信息学技术解析稳定（eAAA）和破裂AAA（rAAA）之间不同的免疫调节模式，发现在rAAA中，naïve B细胞、CD4+T细胞等显著升高，Treg细胞、肥大细胞在rAAA中则相对较少，PTX3与补体系统和B细胞的相互作用可能参与了AAA的形成和发展；4、利用生物信息学技术解析胸主动脉瘤（TAA）的免疫细胞组成、血管壁内中膜与外膜等方面基因表达差异；5、发现免疫蛋白酶体激活促进AAA中巨噬细胞焦亡反应，主要通过调节IκB/NF-κB 信号通路；6、发现AAA中CCL25/TECK、Ccl9/MIP-1g等相关基因表达上调，G-CSF，MIP-1g，CT-1，MFG-E8，IL-33等尚未报导，进一步通过通路富集分析发现细胞因子-细胞因子受体信号通路、Jak-STAT信号通路等相关差异蛋白更为富集；7、对小鼠AAA组织基因芯片检测结果进行生物信息学分析，发现蛋白酶相关信号通路中，Ctsa、Ctsw、Mmp16和Mmp17为差异表达的中枢基因；8、应用计算流体力学（CFD）分析主动脉重建术后血栓形成模式，预测血管重建结局。本课题揭示了CXCR2、免疫蛋白酶体等在AAA形成中的调节作用及分子机制，发现CXCR2拮抗剂SB265610和SB225002、PR-957等药物对于AAA的治疗作用。利用组学及生物信息学分析等手段，筛选代谢组学、细胞免疫等方面差异表达基因与蛋白，为AAA循环标记物筛查及转化提供重要参考。课题在研期间，本课题组共发表相关SCI文章28篇，累计影响因子125.777，核心期刊文章8篇。指导22名学生课题设计，指导8名研究生毕业，晋升高级职称1人、中级职称1人，获批专利6项，组织国际性学术会议4次、全国性学术会议8次。