Zuhdi Alimam M, Piazza F M, Selby D M, Letwin N, Huang L, Rose M C
Department of Allergy, Immunology, and Pulmonary Medicine, Children's Research Institute, Children's National Medical Center, George Washington University, Washington, District of Columbia 20010, USA.
Am J Respir Cell Mol Biol. 2000 Mar;22(3):253-60. doi: 10.1165/ajrcmb.22.3.3768.
Airway inflammation, hyperreactivity, increased number of goblet cells, and mucus overproduction characterize asthma. Respiratory challenge with ovalbumin (OVA) of sensitized mice has been shown by several laboratories to cause pulmonary pathology similar to that observed in human allergic asthma. Recently, interleukin (IL)-13 has been shown to be a central mediator in this process. Because the airways of healthy mice have few, if any, mucus-producing cells, an increase in the number of these cells likely reflects induction of mucin-gene expression. The purpose of this study was to identify mucin genes induced as a result of airway goblet-cell metaplasia (GCM) in mice sensitized and challenged with OVA or in mice treated with IL-13 alone. BALB/c mice were sensitized by intraperitoneal injection (Days 0, 4, 7, 11, and 14) and intranasal instillation (Day 14) of 100 microg of OVA in saline, and then challenged by intranasal instillation (Days 25, 26, and 27) of the same. IL-13-treated mice received 5 microg of IL-13 by intranasal instillation on three consecutive days. Control mice were given saline alone. All mice were studied 24 h after the last challenge. Histologic analysis of the lungs revealed both a striking peribronchial and perivascular lymphocytic and eosinophilic inflammation and airway GCM in OVA-treated mice, and also airway GCM without inflammation in IL-13-treated mice. Northern blot analysis of lung RNA demonstrated (1) expression of Muc-5/5ac messenger RNA (mRNA) in OVA-treated and IL-13-treated mice, but not in control mice; (2) expression of Muc-1 mRNA at comparable levels in all mice regardless of treatment; and (3) no expression of Muc-2 or Muc-3 mRNA in control or treated mice. Western blot analysis demonstrated the expression of Muc-5/5ac protein (both apomucin and glycosylated mucin) in lung lysates of OVA-treated (but not control) mice, and also the expression of Muc-5/5ac mucins in the bronchoalveolar lavage fluid of OVA-treated and IL-13-treated mice. These findings demonstrate that airway GCM is associated with the induction of pulmonary expression of Muc-5/5ac mRNA and mucin in murine models of allergic asthma.
气道炎症、高反应性、杯状细胞数量增加以及黏液过度产生是哮喘的特征。多个实验室已证实，用卵清蛋白（OVA）对致敏小鼠进行呼吸道激发会导致肺部病理变化，类似于人类过敏性哮喘中观察到的情况。最近，白细胞介素（IL）-13已被证明是这一过程的核心介质。由于健康小鼠的气道中几乎没有（如果有的话）产生黏液的细胞，这些细胞数量的增加可能反映了黏蛋白基因表达的诱导。本研究的目的是确定在经OVA致敏和激发的小鼠或仅用IL-13处理的小鼠中，由于气道杯状细胞化生（GCM）而诱导的黏蛋白基因。BALB/c小鼠通过腹腔注射（第0、4、7、11和14天）和在第14天经鼻滴注100μg溶于生理盐水的OVA进行致敏，然后在第25、26和27天经鼻滴注相同物质进行激发。用IL-13处理的小鼠连续三天经鼻滴注5μg IL-13。对照小鼠仅给予生理盐水。在最后一次激发后24小时对所有小鼠进行研究。对肺组织的组织学分析显示，在经OVA处理的小鼠中，既有显著的支气管周围和血管周围淋巴细胞及嗜酸性粒细胞炎症，又有气道GCM，而在经IL-13处理的小鼠中，只有气道GCM而无炎症。对肺RNA的Northern印迹分析表明：（1）Muc-5/5ac信使核糖核酸（mRNA）在经OVA处理和经IL-13处理的小鼠中表达，但在对照小鼠中不表达；（2）无论处理如何，Muc-1 mRNA在所有小鼠中的表达水平相当；（3）对照小鼠或处理过的小鼠中均无Muc-2或Muc-3 mRNA表达。蛋白质印迹分析表明，Muc-5/5ac蛋白（脱辅基黏蛋白和糖基化黏蛋白）在经OVA处理（而非对照）的小鼠肺裂解物中表达，并且Muc-5/5ac黏蛋白在经OVA处理和经IL-13处理的小鼠的支气管肺泡灌洗液中也有表达。这些发现表明，在过敏性哮喘的小鼠模型中，气道GCM与肺中Muc-5/5ac mRNA和黏蛋白表达的诱导有关。
