Leukocyte Biology Section, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, United Kingdom.
J Allergy Clin Immunol. 2010 Dec;126(6):1277-83.e3. doi: 10.1016/j.jaci.2010.08.013. Epub 2010 Oct 8.
Epithelial cell expression of calcitonin gene-related peptide (CGRP) is a feature of provoked asthma. Receptor activity modifying protein 1 (RAMP1) and the calcitonin receptor-like receptor combine to form the CGRP1 receptor.
To determine whether functional RAMP1 is expressed by airway epithelial cells and whether there are alterations in asthma.
BEAS-2B and A549 cells lines were studied by RT-PCR, confocal microscopy, a quantitative immunofluorescence assay, and ELISA. Bronchial biopsies from normal subjects and subjects with asthma were examined by immunohistochemistry and in situ hybridization.
Inflammatory cytokines induced CGRP release and CGRP mRNA in BEAS-2B and A549 epithelial cell lines. RAMP1 was highly expressed by resting, unstimulated BEAS-2B and A549 cells. CGRP induced internalization of RAMP1 and IL-6 production, both of which were inhibited by the CGRP antagonist, CGRP(8-37). Activation of BEAS-2B and A549 cells by inflammatory cytokines induced CGRP secretion, binding of CGRP to RAMP1, and RAMP1 internalization, which was blocked by CGRP (8-37). RAMP1 immunoreactivity and RAMP1 mRNA expression in bronchial biopsies from subjects with asthma were significantly lower than in normal subjects (P = .002 and P = .007, respectively). Inhalational challenge of atopic subjects with asthma with allergen-derived peptides produced a significant decrease in the numbers of RAMP1-positive epithelial cells in responders (P = .027) but not nonresponders.
Receptor activity modifying protein 1 was expressed both by airway epithelial cells in culture and in bronchial biopsies from normal subjects and internalized after epithelial cell activation through autocrine feedback of CGRP. There is an apparent dysregulation of RAMP1 in asthmatic epithelium, suggesting continuous stimulation of pathways involving CGRP.
降钙素基因相关肽（CGRP）在诱导性哮喘中的上皮细胞表达是其特征之一。受体活性修饰蛋白 1（RAMP1）和降钙素受体样受体结合形成 CGRP1 受体。
确定气道上皮细胞是否表达功能性 RAMP1，以及哮喘是否存在改变。
通过 RT-PCR、共聚焦显微镜、定量免疫荧光测定和 ELISA 研究 BEAS-2B 和 A549 细胞系。通过免疫组织化学和原位杂交检查正常受试者和哮喘受试者的支气管活检。
炎症细胞因子诱导 BEAS-2B 和 A549 上皮细胞系中 CGRP 的释放和 CGRP mRNA。静止、未刺激的 BEAS-2B 和 A549 细胞高度表达 RAMP1。CGRP 诱导 RAMP1 内化和 IL-6 产生，CGRP 拮抗剂 CGRP（8-37）可抑制这两种作用。炎症细胞因子激活 BEAS-2B 和 A549 细胞诱导 CGRP 分泌、CGRP 与 RAMP1 结合以及 RAMP1 内化，CGRP（8-37）可阻断这些作用。哮喘受试者支气管活检中 RAMP1 免疫反应性和 RAMP1 mRNA 表达明显低于正常受试者（P 分别为.002 和.007）。对哮喘的特应性受试者进行吸入性过敏原肽激发试验，结果显示，应答者（P ＝.027）而非无应答者气道上皮细胞中 RAMP1 阳性细胞数量明显减少。
气道上皮细胞在培养中以及正常受试者的支气管活检中均表达 RAMP1，并且在 CGRP 自分泌反馈作用下，上皮细胞激活后 RAMP1 发生内化。哮喘上皮细胞中 RAMP1 明显失调，提示涉及 CGRP 的途径持续受到刺激。
