BACKGROUND For still unclear reasons, chronic airway infection often occurs in patients with Chronic Obstructive Pulmonary Disease (COPD), particularly in those with more severe airflow limitation. Fatty-acid binding protein 4 (FABP4) is an adipokine involved in the innate immune response against infection produced by alveolar macrophages (Mɸ). We hypothesized that airway levels of FABP4 may be altered in COPD patients with chronic airway infection. METHODS In this prospective and controlled study we: (1) compared airway FABP4 levels (ELISA) in induced sputum, bronchoalveolar lavage fluid (BALF) and plasma samples in 52 clinically stable COPD patients (65.2 ± 7.9 years, FEV1 59 ± 16% predicted) and 29 healthy volunteers (55.0 ± 12.3 years, FEV1 97 ± 16% predicted); (2) explored their relationship with the presence of bacterial airway infection, defined by the presence of potentially pathogenic bacteria (PPB) at ≥103 colony-forming units/ml in BALF; (3) investigated their relationship with the quantity and proportion of Mɸ in BALF (flow cytometry); and, (4) studied their relationship with the severity of airflow limitation (FEV1), GOLD grade and level of symptoms (CAT questionnaire). RESULTS We found that: (1) airway levels of FABP4 (but not plasma ones) were reduced in COPD patients vs. controls [219.2 (96.0-319.6) vs. 273.4 (203.1-426.7) (pg/ml)/protein, p = 0.03 in BALF]; (2) COPD patients with airway infection had lower sputum FABP4 levels [0.73 (0.35-15.3) vs. 15.6 (2.0-29.4) ng/ml, p = 0.02]; (3) in COPD patients, the number and proportion of Mɸ were positively related with FABP4 levels in BALF; (4) BALF and sputum FABP4 levels were positively related with FEV1, negatively with the CAT score, and lowest in GOLD grade D patients. CONCLUSIONS Airway FABP4 levels are reduced in COPD patients, especially in those with airway infection and more severe disease. The relationship observed between Mɸ and airway FABP4 levels supports a role for FABP4 in the pathogenesis of airway infection and disease severity in COPD.

中文翻译：

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COPD中脂肪酸结合蛋白4的气道水平降低：与气道感染和疾病严重程度的关系。

背景技术由于仍然不清楚的原因，慢性气道感染经常发生在慢性阻塞性肺疾病（COPD）患者中，特别是在气流受限严重的患者中。脂肪酸结合蛋白4（FABP4）是一种脂肪因子，参与了针对肺泡巨噬细胞（Mɸ）产生的感染的先天免疫应答。我们假设在患有慢性气道感染的COPD患者中FABP4的气道水平可能改变。方法在这项前瞻性和对照研究中，我们：（1）在52例临床稳定的COPD患者（65.2±7.9岁，FEV1 59±16％预测值）中比较了诱导痰，支气管肺泡灌洗液（BALF）和血浆样本中的气道FABP4水平（ELISA） ）和29名健康志愿者（55.0±12.3岁，预测的FEV1 97±16％）；（2）探讨了它们与细菌性气道感染的关系，通过BALF中≥103菌落形成单位/ ml的潜在病原菌（PPB）的存在来定义; （3）研究了它们与BALF中Mɸ的数量和比例的关系（流式细胞仪）；（4）研究了它们与气流受限严重程度（FEV1），GOLD等级和症状水平（CAT问卷）的关系。结果我们发现：（1）COPD患者相对于对照组[219.2（96.0-319.6）vs. 273.4（203.1-426.7）（pg / ml）/ pg，蛋白，p，FABP4（但不是血浆）的气道水平降低了= 0.03 in BALF]; （2）患有气道感染的COPD患者的痰FABP4水平较低[0.73（0.35-15.3）vs. 15.6（2.0-29.4）ng / ml，p = 0.02]；（3）COPD患者Mɸ的数量和比例与BALF中FABP4水平呈正相关；（4）BALF和痰中FABP4水平与FEV1呈正相关，CAT评分为阴性，在GOLD D级患者中最低。结论在COPD患者中，尤其是在患有气道感染和更严重疾病的患者中，气道FABP4水平降低。Mɸ与气道FABP4水平之间的关系支持了FABP4在COPD中气道感染的发病机理和疾病严重程度中的作用。