目的·观察孟鲁司特在哮喘治疗中对白三烯B4（leukotriene B4，LTB4）代谢途径关键分子表达的影响，探讨哮喘的潜在干预靶点。方法·卵清蛋白（ovalbumin，OVA）+Al（OH）₃致敏激发小鼠，建立以过敏性气道疾病（allergic airway disease，AAD）为特点的小鼠急性、亚急性和慢性哮喘模型并予孟鲁司特灌胃干预，然后再予OVA激发慢性哮喘模型。无约束全身体积描记仪测定小鼠肺功能，探究气道高反应性（airway hyperresponsiveness，AHR）的变化规律。苏木精-伊红（hematoxylin-eosin，HE）染色观察肺组织嗜酸性粒细胞（eosinophil，EOS）浸润及杯状细胞（goblet cell，GCL）增生情况，观察气道过敏性炎症的病理学特点。ELISA和液相芯片多因子检测试剂盒检测支气管肺泡灌洗液（bronchoalveolar lavage fluid，BALF）和血清的免疫球蛋白E（immunoglobulin E，IgE）、干扰素γ（interferon γ，IFN-γ）和白细胞介素（interleukin，IL）表达水平，观察2型辅助性T细胞（helper T cell type 2，Th2）炎症情况。RT-qPCR、Western blotting及免疫组织化学检测小鼠LTB4合成限速酶5-脂氧合酶激活蛋白（5-lipoxygenase activating protein，ALOX5AP）和白三烯A4水解酶（leukotriene A4 hydrolase，LTA4H）及LTB4受体1（leukotriene B4 receptor 1，BLT1）基因及蛋白表达，探究LTB4的代谢与哮喘的关系。结果·OVA+Al（OH）₃可建立以AAD为特征的小鼠哮喘模型，表现为以增强呼气间歇（enhanced pause，Penh）值升高为肺功能特点的AHR，以气道EOS浸润和GCL增生为病理学特点的嗜酸性炎症和黏液高分泌状态，及以BALF和血清中IgE、IL-4和IL-13升高且IFN-γ、IL-2和IL-12降低为免疫学特点的Th2型炎症反应；孟鲁司特可有效缓解AAD。ALOX5AP、LTA4H和BLT1基因及蛋白在哮喘中表达增强，孟鲁司特始终抑制ALOX5AP表达，但可促进LTA4H和BLT1在慢性期的表达。OVA再次激发后，孟鲁司特可使LTA4H和BLT1表达增强。结论·孟鲁司特具有缓解哮喘小鼠过敏性炎症的效应，但可刺激LTB4的生成和堆积并以慢性期显著；再次予OVA激发孟鲁司特持续干预的哮喘小鼠可使LTB4与BLT1的表达增强；孟鲁司特可能存在激活LTB4及其受体BLT1进而加重哮喘发作的风险，LTB4代谢限速酶LTA4H及受体BLT1可能是哮喘治疗的潜在靶点。

Objective ·To observe the effect of montelukast on the expressions of key genes in LTB4 (leukotriene B4) metabolic pathway in treating asthma and investigate the candidate intervene targets of asthma. Methods ·The acute, subacute, and chronic asthmatic mouse models characterizing by allergic airway disease (AAD) were set up by ovalbumin (OVA) and Al(OH)₃ sensitization and challenge and intervened by intragastric administration of montelukast and finally challenged by OVA for chronic asthma model. The pulmonary functions of mice were tested by unconstrained whole body plethysmograph, to quest the change patterns of airway hyperresponsiveness (AHR). The eosinophil (EOS) infiltration and goblet cell (GCL) hyperplasia in mouse lungs were detected by hematoxylin-eosin (HE) staining, to quest the pathologic features of airway allergic inflammation. The levels of immunoglobulin E (IgE), interferon γ (IFN-γ), and interleukin (IL) in bronchoalveolar lavage fluid (BALF) and serum were detected by ELISA and Milliplex kits, to quest the helper T cell type 2 (Th2) inflammation status. The transcription and protein levels of 5-lipoxygenase activating protein (ALOX5AP), leukotriene A4 hydrolase (LTA4H), and leukotriene B4 receptor 1 (BLT1) genes, which encoded the rate-limiting enzymes in LTB4 synthesis pathway, were detected by RT-qPCR, Western blotting and immunohistochemistry (IHC). Results ·The asthmatic mouse model could be set up by OVA and Al (OH)₃ and was presented as AHR characterized by increasing enhanced pause (Penh) value, eosinophilic inflammation and high mucous secretion pathologically characterized by airway EOS infiltration and GCL hyperplasia, Th2 inflammation immunologically characterized by the increasing levels of IgE, IL-4, and IL-13 as well as decreasing levels of IFN-γ, IL-2, and IL-12 in BALF and serum. Montelukast could alleviate AAD effectively. The transcription and protein levels of ALOX5AP, LTA4H, and BLT1 genes increased in asthma. Montelukast can inhibit the expression of ALOX5AP gene and promote the expressions of LTB4 and BLT1 genes in asthmatic chronic phase. When challenged by OVA once again, montelukast can induce the significantly high expressions of LTB4 and BLT1 genes. Conclusion ·Montelukast has the effect of relieving allergic inflammation in asthma mice, but it can stimulate the production and accumulation of LTB4 and is significant in chronic phase. When challenged by OVA a second time, LTB4 could be promoted to combine with BLT1 and attend in the pathogenesis of asthma. The results suggested that there was a potential risk of activation of LTB4 by montelukast. The rate-limiting enzyme LTA4H and its receptor BLT1 metabolism may be potential targets for asthma treatment.