CD23-IgE介导跨上皮转运在变应性鼻炎发病机制中的作用

For inhaled allergens to gain access to immune effector cells in the lamina propria, they must ?rst cross the nasal epithelium. Nasal epithelium cells can form a highly regulated and impermeable barrier made possible through the formation of tight junctions localized in the apical part of the columnar cells. Tight junctions prevent the free uptake and passage of macromolecules such as IgE and allergens. Hence, the exact mechanisms responsible for the cross-talk between allergen/IgE and immune effector cells in the airway remains poorly understood.Several elegant studies have demonstrated a potential function for CD23 to transport IgE and IgE-derived immune complex (IC) across the polarized intestinal epithelial monolayer . Furthermore, the facilitated transport of IgE and uptake of Ags by CD23 are essential steps in the initiation of rapid allergic in?ammation in the intestine in a murine model. However, it remains completely unknown whether a similar mechanism of transport of IgE or IC exists in human nasal epithelium.Our objectives of the subject are to investigate CD23 expression of nasal epithelial cells in a murine model of allergic rhinitis, to investigate the role of p38 mitogen-activated protein kinase signal transduction pathway in nasal epithelial cells up-regulation of CD23, to investigate whether CD23 is capable of transporting human IgE or IgE-derived IC across polarized human nasal epithelial monolayers and to investigate whether inhibition of CD23 expression with a small interfering RNA in vitro and in vivo results in abolition of the initiation of allergic rhinitis. Our ?ndings would provide important evidence that CD23 in human airway epithelial cells is very likely to have a pivotal role in the initiation and development of airway allergic in?ammation. This study would also suggest that blocking CD23-mediated IgE transport is a potentially important target to treat allergic rhinitis .

上皮细胞之间紧密连接的存在，阻碍了大分子变应原自由通过上皮细胞层。大分子变应原如何通过鼻黏膜上皮和黏膜固有层与免疫效应细胞接触的机制尚不清楚。有研究显示，消化道上皮细胞表达CD23能易化转运IgE和变应原，是启动快速的变应性炎症的必要步骤。然而，鼻黏膜上皮细胞表达CD23是否具有跨上皮转运作用，以及过敏状态鼻黏膜上皮细胞表达CD23的变化情况如何，尚未阐明。本课题拟以小鼠变应性鼻炎模型为研究对象，在蛋白及mRNA水平检测其鼻黏膜上皮CD23的表达情况，探讨鼻黏膜上皮上调CD23表达的信号通路；研究鼻黏膜上皮细胞表达的CD23是否具有转运IgE和IgE免疫复合物通过极化的鼻黏膜上皮的功能，并用小干扰RNA在变应性鼻炎动物模型体内外抑制CD23的表达，观察其对变应性鼻炎发病的影响。通过上述研究，力图阐明CD23-IgE介导跨上皮转运在变应性鼻炎发病机制中的作用，为治疗变应性鼻炎寻找新的靶点。

结题摘要 .本项目主要内容包括：1. 免疫组化和Western Blot发现CD23结构性的表达于小鼠鼻粘膜上皮细胞，在过敏状态下其表达发生了上调；在体内，CD23在鼻腔粘膜上皮细胞的上调与小鼠血清IL-4水平呈正相关，小鼠鼻腔灌洗液中IgE水平与CD23在鼻腔粘膜上皮细胞表达的量亦呈正相关。2. 免疫荧光双标法示CD23-IgE的结合位点可位于鼻粘膜纤毛柱状上皮细胞顶面和基底面区域的细胞膜和细胞浆，变应性鼻炎患者鼻粘膜组织切片可见大量结合点，对照患者鼻粘膜组织切片偶见；3.原位杂交染色显示CD23a、CD23b mRNA均表达于人鼻粘膜上皮细胞，变应性鼻炎患者染色强度明显高于对照患者。4. 免疫细胞化学和Western Blot示IL-4上调体外培养鼻黏膜上皮细胞CD23的表达。5. CD23可以介导IgE在透性支持物上的上皮细胞单层顶面-底面，底面-顶面的双向转运，亦可介导IgE抗原复合物从上皮细胞单层顶面转运至底面，阻断CD23与IgE结合这种跨上皮转运现象变弱，IgE和IgE抗原复合物通过IL-4刺激后鼻上皮细胞单层的水平高于未刺激的鼻黏膜上皮细胞单层。以上结果表明CD23介导的跨上皮转运IgE和IgE变应原免疫复合物在变应性鼻炎发病机制中起重要作用，鼻粘膜上皮表达的CD23可作为变应性鼻炎治疗的新靶点。