Leukocyte Adhesion in Allergic Inflammation

描述（由申请人提供）：过敏性炎症是一种复杂的疾病，涉及多种白细胞（包括嗜酸性粒细胞和T细胞）向炎症部位的运输和动员。在气道变应性炎症过程中观察到Th 2细胞因子、趋化因子、血管粘附分子和生长因子的表达增加，导致炎症反应加剧，包括气道过度活动（AHR）增加、气道重塑和肺血管生成。由于嗜酸性粒细胞在过敏性炎症的发病机制中起着重要作用，在过去的十年中，我们将注意力集中在这种细胞类型产生的机制上，它如何与血管内皮相互作用，以及它如何被招募到炎症部位。这些研究已经鉴定了参与嗜酸性粒细胞隔离到不同血管床如腹膜和肺血管床的关键分子。我们的初步研究表明，除了细胞表面选择素和整联蛋白，半乳糖凝集素-3（Gal-3），一种碳水化合物结合凝集素，识别由MgatS表达的N-聚糖，可以（i）作为一种新的血管和细胞粘附分子，以支持嗜酸性粒细胞的运输，（ii）参与Th 2细胞因子的产生和（iii）诱导小鼠AHR。在这个竞争性的延续中，我们假设Gal-3以及MgatS表达的N-聚糖在急性和慢性气道过敏性炎症包括哮喘的发病机制中起重要作用。为了研究这个问题，我们提出了三个具体目标。在第一个目标中，使用活体显微镜，我们将检查Gal-3作为一种新的粘附分子的功能，其通过与多种配体结合来支持细胞粘附，所述配体包括含有聚N-乙酰乳糖胺残基的N-聚糖、VCAM-1和α 4整联蛋白，以支持在不同血管床中的流动条件下嗜酸性粒细胞的运输。在下一个目标中，使用Gal-3-/-和Mgat-5-/-小鼠，我们将确定Gal-3和Mgat-5在介导免疫应答中的作用，包括AHR、粘附分子和趋化因子的表达、Th 1/Th 2细胞因子释放、肥大细胞活化和慢性过敏性炎症期间炎性白细胞的存活。最后，基于我们观察到Gal-3在慢性过敏原攻击小鼠中与气道重塑相关的气道和肺组织中表达，我们提出利用Gal-3-/-和Mgat-5-/-小鼠来检查Gal-3及其由MgatS表达的含N-聚糖的配体促进与过敏性炎症相关的气道重塑和肺血管生成的机制。总体而言，拟议的研究将描绘Gal-3及其配体在气道过敏性炎症的急性和慢性阶段的重要性。了解凝集素-碳水化合物相互作用在过敏性炎症中的作用有可能导致开发用于治疗过敏性疾病的基于聚糖的疗法（或其模拟物）。

DESCRIPTION (provided by applicant): Allergic inflammation is a complex disease that involves the trafficking and mobilization of multiple leukocytes, including eosinophils and T-cells, to sites of inflammation. Increased expression of Th2 cytokines, chemokines, vascular adhesion molecules and growth factors leading to exacerbation of the inflammatory response, including increased airway hyperactivity (AHR), airway remodeling and pulmonary angiogenesis are observed during airway allergic inflammation. Since eosinophils play an important role in the pathogenesis of allergic inflammation, in the last decade we have focused our attention on the mechanisms by which this cell type is generated, how it interacts with the vascular endothelium and how it is recruited to sites of inflammation. These studies have resulted in the identification of key molecules involved in the sequestration of eosinophils to different vascular beds such as the peritoneum and the pulmonary vascular bed. Our preliminary studies suggest that in addition to cell surface selectins and integrins, galectin- 3 (Gal-3), a carbohydrate-binding lectin that recognizes N-glycans expressed by MgatS, can (i) function as a novel vascular and cell adhesion molecule to support eosinophil trafficking, (ii) participate in the generation of Th2 cytokines and (iii) induce AHR in mice. In this competing continuation, we hypothesize that Gal-3 as well as N-glycans expressed by MgatS play an important role in the pathogenesis of acute and chronic airway allergic inflammation including asthma. To examine this, we have proposed three specific aims. In the first aim, using intravital microscopy, we will examine the function of Gal-3 as a novel adhesion molecule that supports cell adhesion by binding to multiple ligands, including N-glycans containing poly N- acetyllactosamine residues, VCAM-1 and alpha4 integrins, to support trafficking of eosinophils under conditions of flow in different vascular beds. In the next aim, using Gal-3-/- and Mgat-5-/- mice, we will determine the role of Gal-3 and Mgat5 in mediating immune responses including, AHR, expression of adhesion molecules and chemokines, Th1/Th2 cytokine release, mast cell activation and survival of inflammatory leukocytes during chronic allergic inflammation. Finally, based on our observation that Gal-3 is expressed in the airways and lung tissue associated with airway remodeling in chronically allergen-challenged mice, we propose to examine the mechanisms by which Gal-3 and its N-glycan-containing ligands expressed by MgatS promote airway remodeling and pulmonary angiogenesis associated with allergic inflammation utilizing Gal-3-/- and Mgat-5-/- mice. Overall, the proposed studies will delineate the importance of Gal-3 and its ligands in acute and chronic phases of airway allergic inflammation. Understanding the role of lectin-carbohydrate interactions in allergic inflammation has the potential to lead to the development of glycan-based therapies (or their mimetics) for the treatment of allergic diseases.