Galectin-3 in regulation of allergic skin inflammation

特应性皮炎是一种常见的慢性炎症性皮肤病。这是一个重大的医学问题，在工业化国家，多达15%-20%的儿童受到这种疾病的影响。特应性皮炎的治疗仍然是一个挑战。目前的模型表明，特应性皮炎可归因于Th2介导的炎症反应，T细胞、树突状细胞和肥大细胞发挥重要作用。这项建议旨在确定Galectin家族成员在特应性皮炎中的作用，长期目标是开发一种治疗这种疾病的新疗法。Galectin-3是动物凝集素家族中的一员，由它们对2-半乳糖苷和共同序列的亲和力所定义。它由多种类型的细胞表达，包括上皮细胞和各种白细胞。通过使用外源添加的Galectin-3，已经证明了许多细胞外功能，这些功能与其与细胞表面多糖的结合和交联有关。然而，大量证据表明，内源性Galectin-3通过细胞内作用调节多种细胞功能。通过对Galectin-3缺陷小鼠T细胞的研究，我们证明Galectin-3是Th1细胞的抑制调节因子，并通过促进TCR下调来抑制T细胞受体(TCR)介导的Th1反应。Galectin-3定位于TCR激活的T细胞的免疫突触内。我们还证明了Galectin-3抑制树突状细胞产生IL-12。此外，我们还证明了Galectin-3在肥大细胞中的重要作用。通过酵母双杂交筛选，我们发现Alix是Galectin-3结合的伙伴，它是运输所需的内体分选复合体(ESCRT)和多囊泡体(MVB)的组成部分。我们还有其他信息表明Galectin-3与MVB和外切体有关。在特应性皮炎的小鼠模型中，我们发现Galectin-3促进Th2反应，抑制Th1反应，这在一定程度上是通过该蛋白在T细胞和树突状细胞中的功能实现的。在这项提案中，我们计划测试Galectin-3)通过在IS发挥作用来抑制TCR介导的Th1反应的假设；2)通过抑制IL-12的产生而对树突状细胞的抗原提呈功能至关重要，并作为外切体相关蛋白发挥作用；3)通过树突状细胞和肥大细胞(除T细胞外)促进过敏性皮肤炎症。 公共卫生相关性：特应性皮炎是一种常见的慢性炎症性皮肤病。在过去30年里，工业化国家的这种疾病的流行率增加了两到三倍，目前这些国家的儿童流行率估计为15%-20%。这种疾病的治疗仍然是一个挑战。阐明这种疾病的细胞和分子基础对于开发新的治疗策略是重要的。Galectin-3是一种结合碳水化合物的蛋白质家族的成员，称为凝集素。半乳糖凝集素家族，由它们与2-半乳糖苷的结合和相似的氨基酸序列所定义。当Galectin-3被加入到各种细胞中时，它可以结合到细胞表面的蛋白质上，这些蛋白质上附着着凝集素可识别的碳水化合物。然而，有大量证据表明，存在于细胞内的Galectin-3通过细胞内的作用(不分泌蛋白质)调节各种细胞功能。我们通过研究我们培育的缺乏Galectin-3的基因工程小鼠，获得了关于Galectin-3功能的重要信息。最近，我们发现Galectin-3在T细胞的反应中起着重要作用。我们发现Galectin-3聚集在对T细胞反应重要的区域的细胞内，称为免疫突触。我们还发现Galectin-3在另一种称为树突状细胞的细胞中具有重要功能。我们之前已经证明Galectin-3促进过敏性呼吸道炎症。我们现在有大量的数据支持这种蛋白在特应性皮炎小鼠模型中的作用。要了解Galectin-3如何调节这些炎症过程，并推进开发Galectin-3靶向疗法的策略，还需要进行更多的工作。在这项建议中，我们计划建立Galectin-3调节T细胞和树突状细胞反应的机制，这两种细胞类型都是与特应性皮炎相关的过敏性皮肤炎发生的关键细胞类型。我们还计划阐明Galectin-3‘S在特应性皮炎小鼠模型中调节作用的细胞基础。

DESCRIPTION (provided by applicant): Atopic dermatitis is a common chronic inflammatory skin disease. It is a significant medical problem and as much as 15-20% of children are affected by this disease in industrialized countries. Treatment of atopic dermatitis continues to be a challenge. The current model suggests that atopic dermatitis is attributable to a Th2-mediated inflammatory response and T cells, dendritic cells, and mast cells play important roles. This proposal aims at the establishment of the role of a member of the galectin family in atopic dermatitis with the long-term goal of developing a novel therapy for treatment of this disease. Galectin-3 is a member of a family of animal lectins defined by their affinity for 2-galactosides and consensus sequences. It is expressed by a number of cell types, including epithelial cells and various leukocytes. A number of extracellular functions have been demonstrated by using exogenously added galectin-3 and these are associated with its binding to and crosslinking cell surface glycans. However, there is a great deal of evidence that endogenous galectin-3 regulates various cellular functions through intracellular actions. By studying T cells from galectin-3-deficient mice, we have demonstrated that galectin-3 is an inhibitory regulator in Th1 cells and suppresses the T cell receptor (TCR)-mediated Th1 response by promoting TCR downregulation. Galectin-3 is localized intracellularly at the immunological synapse in T cells activated by TCR engagement. We have also demonstrated that galectin-3 suppresses the production of IL-12 by dendritic cells. In addition, we have demonstrated an important role of galectin-3 in mast cells. By yeast two-hybrid screening, we found Alix as a galectin-3-binding partner, which is known to be a component of the endosomal sorting complex required for transport (ESCRT) and the multivesicular body (MVB). We also have other information suggesting that galectin-3 is associated with MVBs and exosomes. In a mouse model of atopic dermatitis, we found that galectin-3 promotes the Th2 response and suppresses the Th1 response and this is in part through the protein's function in T cells and dendritic cells. In this proposal, we plan to test the hypothesis that galectin-3 1) suppresses the TCR-mediated Th1 response by functioning at the IS; 2) is critical for the antigen-presenting function of dendritic cells by suppressing IL-12 production and functions as an exosome-associated protein; 3) promotes allergic skin inflammation through dendritic cells and mast cells (in addition to T cells). PUBLIC HEALTH RELEVANCE: Atopic dermatitis is a common chronic inflammatory skin disease. The prevalence of this disease has increased by two- to three-fold during the past three decades in industrialized countries, where the current prevalence in children is estimated to be 15-20%. The treatment of this disease continues to be a challenge. Elucidation of the cellular and molecular bases of this disease is important for development of novel therapeutic strategies. Galectin-3 is a member of a family of proteins that bind carbohydrates, called lectins. The galectin family defined by their binding of 2-galactosides and sharing of similar amino acid sequences. When galectin-3 is added to various cells, it can bind to cell surface proteins that have attached carbohydrates recognizable by the lectin. However, there is a great deal of evidence that galectin-3 that is present inside the cells regulates various cellular functions through intracellular actions (without the protein being secreted). We have obtained important information on the functions of galectin-3 by studying genetically engineered mice we generated that lack galectin-3. Most recently, we found that galectin-3 plays an important function in the response of T cells. We found that galectin-3 is clustered inside the cells in the area that is important for the T cell response called the immunological synapse. We also found that galectin-3 has an important function in another cell type called dendritic cells. We have previously demonstrated that galectin-3 promotes allergic airway inflammation. We now have a significant amount of data supporting the role of this protein in a mouse model of atopic dermatitis. Additional work is required for understanding how galectin-3 regulates these inflammatory processes and for advancing strategies for developing galectin-3-targeting therapies. In this proposal, we plan to establish the mechanism by which galectin-3 regulates the responses of T cell and dendritic cell, which are both key cell types in the development of allergic skin inflammation associated with atopic dermatitis. We also plan to elucidate the cellular basis for galectin-3's regulatory role in a mouse model of atopic dermatitis.