Molecular mechanisms of eosinophil recruitment

嗜酸性粒细胞募集的分子机制

• 批准号: 7006089
• 负责人: LARRY A. SKLAR
• 金额: $ 25.48万
• 依托单位: UNIVERSITY OF NEW MEXICO
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7006089
• 关键词: allergens; asthma; basophils; cell adhesion; cell adhesion molecules; cell migration; cytokine; eosinophil; flow cytometry; inflammation; leukocyte adhesion molecules; molecular pathology; receptor binding; selectins; tissue /cell culture; transfection; vascular cell adhesion molecule

(Applicant's Abstract) Following allergen exposure, eosinophils (Eos) and basophils (Basos) but not neutrophils (PMNs) are preferentially recruited to the lung in a Th2 environment supported by dendritic cells. The sequence of events is likely to include the release of histamine from resident mast cells within min of allergen binding. The presence of histamine is expected to lead within min to an upregulation of P-selectin on vascular endothelial cells that can serve in the initial Eo and Baso adherence. Within min to hrs, allergen specific Th2 cytokines IL4, IL-5, and IL-13 are generated by mast cells and T cells. IL4 and IL-13 regulate the expression of adhesion molecules on the endothelium. IL-5 enables VLA-4 dependent adhesion of Eos and Basos while the asthma specific chemokines that bind to CCR3 enable VLA-4 and LFA-1 dependent firm adhesion and transmigration. As a consequence Eos and Basos accumulate in bronchial mucosa and mucous cell metaplasia can arise later from bronchiolar inflammation. These considerations provide a temporal and mechanistic framework for analysis of Eo and Baso recruitment following allergen. We have shown that Eos use their P-selectin glycoprotein ligand (PSGL-1) to attach to CHO cells expressing low levels of P-selectin. At the low site density of P-selectin of endothelial cells, Eos attach preferentially as compared to PMNs in accord with observations that Eos but not PMNs use PSGL-1 to adhere to venules in the lung. The first aim will focus on understanding the mechanism by which Eos and Basos but not PMNs preferentially use their PSGL-1 to engage P-selectin. VLA-4 plays a unique role in the recruitment of Eos and Basos because it can be regulated in distinct conformations that contribute both to cell capture and firm adherence. We have developed several novel real-time assays to examine how IL-5 and chemokine exposure alters the adhesive activity and affinity of VLA-4 on Eos. The second aim is to understand the relationship between the affinity of VLA-4 to the rolling and firm attachment of Basos and Eos. In animal models of allergic asthma, mAbs to P-selectin, VLA-4 and also LFA- 1 block the accumulation of Eos. Because LFA- 1 contributes to specific recruitment in so far as activated by cell specific stimuli, it must work in combination with P-selectin and VLA-4 to enable efficient transmigration. The third aim will evaluate how the adhesion molecules work in combination in the recruitment. Taken together, the work will provide a novel understanding of the attachment of PSGL-1 to P-selectin, the use of VLA-4, and the coordination of the adhesion pathways in asthma.

（申请人的摘要）过敏原暴露，嗜酸性粒细胞（EOS）和 嗜碱性粒细胞（BASO）而不是中性粒细胞（PMN）优先招募 树突状细胞支持的Th2环境中的肺。这 事件的顺序可能包括从居民释放组胺 过敏原结合的分钟内的肥大细胞。存在 组胺有望在最小内导致P-选择素的上调 可以在初始EO和BASO中使用的血管内皮细胞 坚持。在最低到HRS之内，过敏原特异性Th2细胞因子IL4，IL-5和 IL-13由肥大细胞和T细胞产生。 IL4和IL-13调节 内皮上粘附分子的表达。 IL-5启用VLA-4 EOS和BASO的依赖性粘附，而哮喘特异性趋化因子 与CCR3结合启用VLA-4和LFA-1依赖性公司粘附和 轮回。结果，EOS和BASO在支气管粘膜中积累 稍后可能由支气管炎症引起粘液细胞化生。 这些考虑提供了时间和机械框架 用于分析过敏原后EO和BASO募集。我们已经表明 EOS使用其P-选择蛋白糖蛋白配体（PSGL-1）连接到CHO细胞 表达低水平的P-选择素。在低位点密度的P-选择蛋白 内皮细胞，EOS与PMN相比优先附着 观察到EOS但不使用PMN使用PSGL-1粘附在静脉 肺。第一个目标将重点放在理解EOS和EOS的机制上 BASO，而不是PMN优先使用其PSGL-1参与P-选择蛋白。 VLA-4 在招募EOS和BASOS中起着独特的作用，因为它可以是 以不同的构象的调节，既有助于细胞捕获又有助于 坚定的依从性。我们已经开发了一些新颖的实时测定来检查 IL-5和趋化因子暴露如何改变粘附活性和亲和力 EOS上的VLA-4。第二个目的是了解 VLA-4与BASO和EOS的滚动和牢固依恋的亲和力。在 过敏性哮喘的动物模型，对P-选择素的mAb，VLA-4以及LFA-1 阻止EOS的积累。因为LFA- 1有助于特定 在细胞特异性刺激中激活的招聘中，它必须在 与P-选择素和VLA-4结合使用，以实现有效的转移。这 第三目的将评估粘附分子如何合并 招聘。综上所述，这项工作将提供对 PSGL-1与p-选择蛋白的附着，使用VLA-4和协调 哮喘中的粘附途径。