Background Obesity is associated with more severe asthma, however, the mechanisms responsible are poorly understood. Obesity is also associated with low-grade systemic inflammation; it is possible that this inflammation extends to the airways of adults with asthma, contributing to worse asthma outcomes. Accordingly, the aim of this review was to examine whether obesity is associated with increased airway and systemic inflammation and adipokines, in adults with asthma. Methods Medline, Embase, CINAHL, Scopus and Current Contents were searched till 11 August 2021. Studies reporting measures of airway inflammation, systemic inflammation and/or adipokines in obese versus non-obese adults with asthma were assessed. We conducted random effects meta-analyses. We assessed heterogeneity using the I2 statistic and publication bias using funnel plots. Results We included 40 studies in the meta-analysis. Sputum neutrophils were 5% higher in obese versus non-obese asthmatics (mean difference (MD)=5.0%, 95% CI: 1.2 to 8.9, n=2297, p=0.01, I2=42%). Blood neutrophil count was also higher in obesity. There was no difference in sputum %eosinophils; however, bronchial submucosal eosinophil count (standardised mean difference (SMD)=0.58, 95% CI=0.25 to 0.91, p<0.001, n=181, I2=0%) and sputum interleukin 5 (IL-5) (SMD=0.46, 95% CI=0.17 to 0.75, p<0.002, n=198, I2=0%) were higher in obesity. Conversely, fractional exhaled nitric oxide was 4.5 ppb lower in obesity (MD=−4.5 ppb, 95% CI=−7.1 ppb to −1.8 ppb, p<0.001, n=2601, I2=40%). Blood C reactive protein, IL-6 and leptin were also higher in obesity. Conclusions Obese asthmatics have a different pattern of inflammation to non-obese asthmatics. Mechanistic studies examining the pattern of inflammation in obese asthmatics are warranted. Studies should also investigate the clinical relevance of this altered inflammatory response. PROSPERO registeration number CRD42021254525. Data are available upon reasonable request. The data that support the findings of this systematic review and meta-analysis are available from the corresponding author, HAS, upon reasonable request.

中文翻译：

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肥胖对成人哮喘气道和全身炎症的影响：系统评价和荟萃分析

背景 肥胖与更严重的哮喘有关，但其机制尚不清楚。肥胖还与低度全身炎症有关。这种炎症可能会蔓延到成人哮喘患者的气道，导致哮喘结果恶化。因此，本综述的目的是检查成人哮喘患者中肥胖是否与气道、全身炎症和脂肪因子增加有关。方法 检索截止至 2021 年 8 月 11 日的 Medline、Embase、CINAHL、Scopus 和 Current Content。对报告肥胖与非肥胖成人哮喘患者气道炎症、全身炎症和/或脂肪因子测量值的研究进行了评估。我们进行了随机效应荟萃分析。我们使用 I2 统计量评估异质性，并使用漏斗图评估发表偏倚。结果 我们在荟萃分析中纳入了 40 项研究。肥胖哮喘患者的痰中性粒细胞比非肥胖哮喘患者高 5%（平均差 (MD)=5.0%，95% CI：1.2 至 8.9，n=2297，p=0.01，I2=42%）。肥胖者的血液中性粒细胞计数也较高。痰中嗜酸性粒细胞百分比没有差异；然而，支气管粘膜下嗜酸性粒细胞计数（标准化均数差 (SMD)=0.58，95% CI=0.25 至 0.91，p<0.001，n=181，I2=0%）和痰白细胞介素 5 (IL-5) (SMD=0.46) ，95% CI=0.17 至 0.75，p<0.002，n=198，I2=0%）在肥胖人群中较高。相反，肥胖者的呼出一氧化氮分数降低了 4.5 ppb（MD=-4.5 ppb，95% CI=-7.1 ppb 至 -1.8 ppb，p<0.001，n=2601，I2=40%）。肥胖者的血液C反应蛋白、IL-6和瘦素也较高。结论 肥胖哮喘患者与非肥胖哮喘患者具有不同的炎症模式。有必要进行机制研究来检查肥胖哮喘患者的炎症模式。研究还应该调查这种改变的炎症反应的临床相关性。PROSPERO 注册号 CRD42021254525。数据可根据合理要求提供。支持本系统评价和荟萃分析结果的数据可根据合理要求从通讯作者 HAS 处获得。