重度支气管哮喘患者气道炎症及其与白细胞介素17的关系

目的探讨重度支气管哮喘(简称哮喘)患者气道炎症特征及其可能机制,并进一步观察吸入糖皮质激素治疗对气道炎性细胞分类计数、炎症介质、白细胞介素17(IL-17)和IL-8等细胞因子的影响。方法分别选择轻度(轻度组)、中度(中度组)和重度(重度组)持续哮喘患者16例、14例和18例,正常对照组15名,采用基线评估包括哮喘症状控制评分、肺功能测定和用诱导痰检查方法对痰炎性细胞进行分类计数;采用酶联免疫吸附测定(ELISA)法检测痰IL-17和IL-8浓度;采用酶联免疫荧光法测定嗜酸粒细胞阳离子蛋白(ECP)浓度;采用比色法测定中性粒细胞髓过氧化物酶(MPO)浓度,并用痰液蛋白含量进行校正。然后规范吸入糖皮质激素治疗4周,随访轻、中度和重度哮喘患者各15例复查上述指标。结果痰嗜酸粒细胞(EOS)比值和ECP浓度在每克蛋白中轻度组分别为0.0670±0.0740、(155±91)×10-6g;中度组分别为0.0830±0.0440、(180±83)×10-6g;重度组分别为0.1240±0.1430、(191±87)×10-6g,与正常对照组[0.0000±0.0010、(44±25)×10-6g]比较差异有统计学意义(P<0.01);但各哮喘组间比较差异无统计学意义(P>0.05)。中性粒细胞比值在重度组为0.589±0.203,与轻度组(0.455±0.154)、中度组(0.449±0.194)、正常对照组(0.313±0.134)比较差异有统计学意义(P<0.01)。MPO水平在每克蛋白中,重度组为(31±10)U,轻度组为(12±4)U、中度组为(22±7)U,与正常对照组[(10±4)U]比较差异有统计学意义(P<0.01)。IL-17水平在每克蛋白中重度组为(264±137)×10-9g,中度组为(172±65)×10-9g,轻度组为(126±52)×10-9g,与正常对照组[(56±20)×10-9g]比较差异有统计学意义(P<0.01);IL-8浓度在每克蛋白中,重度组为(531±321)×10-9g,轻度组为(410±181)×10-9g,中度组为(438±148)×10-9g,正常对照组为(83±36)×10-9g,重度组与正常对照组比较差异有统计学意义(P<0.01);而轻度组与中度组间比较差异无统计学意义(P>0.05)。IL-17水平与IL-8、中性粒细胞与MPO呈显著相关(r分别为0.525、0.349、0.602,P均<0.01)。经糖皮质激素治疗后,对轻、中、重度30例哮喘患者进行合并分析表明,EOS、ECP、MPO、IL-17和IL-8均显著降低;但两组患者的中性粒细胞比值在治疗后比较差异均无统计学意义(P>0.05);但重度组(0.642±0.157)与轻、中度哮喘组(0.394±0.147)比较差异有统计学意义(P<0.01)。结论中性粒细胞增多是重度哮喘的气道炎症特征之一,IL-17/IL-8可能参与中性粒细胞向气道内的募集。

Characteristics of the airway inflammation and the relationship to interleukin-17 in severe asthma

OBJECTIVE: To investigate the characteristics of airway inflammation in severe asthma and the association with interleukin-17 (IL-17). METHODS: Sixteen patients with mild persistent asthma, 14 patients with moderate persistent asthma and 18 patients with severe persistent asthma, as well as 15 normal control subjects, were included in this study. At baseline, asthma symptom score was recorded, and lung function was measured. Induced sputum was obtained and processed for cell differential and the supernatant was assayed for the concentrations of IL-17 and IL-8 by sandwich enzyme-linked immunosorbent assay (ELISA), eosinophil cationic protein (ECP) by the immuno-CAP system, and neutrophil myeloperoxidase (MPO) by a colorimetric method, and the values were normalized to the protein content. Then 15 mild to moderate and 15 severe asthmatic patients received inhaled corticosteroid (Pulmicort, Astra-Zeneca) therapy for 4 weeks, and the above measurements were repeated. RESULTS: The percentage of sputum eosinophils and the level of ECP were significantly increased in mild [0.0670 +/- 0.0740, (155 +/- 91) x 10(-6) g/g protein], moderate [0.0830 +/- 0.0440, (180 +/- 83) x 10(-6) g/g protein] and severe [0.1240 +/- 0.1430, (191 +/- 87) x 10(-6) g/g protein] asthmatic patients, as compared to the normal controls [0.0000 +/- 0.0010, (44 +/- 25) x 10(-6) g/g protein, P < 0.01)]; but there was no significant difference among mild, moderate and severe asthma (P > 0.05). On the contrary, the percentage of sputum neutrophils was significantly increased in patients with severe asthma (0.589 +/- 0.203) as compared to patients with mild (0.455 +/- 0.154) and moderate (0.449 +/- 0.194) asthma and normal controls (0.313 +/- 0.134, P < 0.01). The level of MPO was also increased in severe asthma [(31 +/- 10 ) U/g protein] as compared to mild [(12 +/- 4) U/g protein] and moderate [(22 +/- 7) U/g protein] asthma and normal controls [(10 +/- 4) U/g protein, P < 0.01]. The sputum level of IL-17 in severe, moderate asthma [(264 +/- 137) x 10(-9) g/g protein, (172 +/- 65) x 10(-9) g/g protein] was significantly higher than those in mild asthma [(126 +/- 52) x 10(-9) g/g protein] and normal controls [(56 +/- 20) x 10(-9) g/g protein, P < 0.01]. As compared to the normal controls [(83 +/- 36) x 10(-9) g/g protein], the level of IL-8 in severe asthma [(531 +/- 321) x 10(-9) g/g protein] was significantly increased (P < 0.01), and those in mild [(410 +/- 181) x 10(-9) g/g protein] and moderate [(438 +/- 148) x 10(-9) g/g protein] asthma were also increased, although the difference was not statistically significant (P > 0.05). The level of IL-17 was correlated positively with IL-8, neutrophils and MPO (r = 0.525, 0.349, 0.602, all P < 0.01). After steroid therapy, the percentage of eosinophils, the levels of ECP, MPO, IL-17 and IL-8 decreased significantly in all patients combined, but the percentage of neutrophils remained unchanged (P > 0.05) and still significantly higher in severe asthmatic patients (0.642 +/- 0.157) as compared to mild and moderate asthmatic patients (0.394 +/- 0.147, P < 0.01). CONCLUSIONS: Airway neutrophilia is a feature of severe asthma. The IL-17/IL-8 pathway may be involved in the initial neutrophil influx into the airways.