肥胖和哮喘的关联是单向还是双向？

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谢华
北部战区总医院总医院 110016

   肥胖和哮喘之间的关联历来被认为是单向的：患有严重哮喘的人活动减少，体重增加，哮喘患者常常需要激素治疗，而口服皮质类固醇的应用进一步导致了体重增加。虽然这组患者不可否认地存在，但越来越多的证据支持提示 BMI 升高、哮喘和哮喘控制不佳之间的存在一定的关系。群组队列研究显示，现在广泛认可的女性为主的肥胖严重哮喘表型[1-3] ，特别影响围绝经期和绝经后妇女[4]。然而，美国的一项大型横断面研究显示，雌二醇(当前哮喘的 OR 为0.43,95% CI 为0.23-0.78)和睾酮(当前哮喘的 OR 为0.59,95% CI 为0.37-0.91)似乎在肥胖哮喘中发挥保护作用[5]。

   肥胖和哮喘之间的联系是复杂的，也许最好认为是双向的[6]。在这些患者队列研究中，肥胖与较差的哮喘控制和生活质量，增加的皮质类固醇使用和急诊就医的相关性在世界各地的许多研究中得到证实[7-9]。

   肥胖已被证明会增加哮喘患者和非哮喘患者的炎症反应[10-11∙]。有研究发现体重指数的增加与血液中性粒细胞和嗜酸性粒细胞计数的增加有关(直到体重指数约40 kg/m2时，嗜酸性粒细胞计数水平下降)。然而，这项研究的另一个有趣的发现是，那些在基线时嗜酸性粒细胞水平升高的人与 BMI 增加呈负相关，表明脂肪过量与炎症之间的关系更加复杂。

   在肥胖性哮喘中使用 SPECT/CT 扫描近显示，与健康 BMI 相比，肺嗜酸性粒细胞摄取增加，进一步增强了肥胖对气道炎症的影响[12]。BMI 升高也通过哮喘患者气道高反应性增加直接影响气道[13]，来自肥胖女性受试者的人气道平滑肌(HASM)细胞比来自肥胖男性受试者的 HASM 细胞对卡巴胆碱更敏感[14]。独立于 BMI 或腰围的内脏脂肪影响哮喘相关的生活质量[15]。其原因包括肺功能降低，相关合并症如胃酸反流和抑郁症增加；然而，脂肪组织及其与炎症的关系无疑是重要的。有进一步的证据支持肥胖相关的合并症，特别是代谢症候群的存在，也会导致较差的哮喘控制[16]。表现为腰围身高比升高的中心性肥胖和胰岛素抵抗对哮喘患者的肺功能有负面影响[17]。

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