Objective: To measure the levels of human alpha-defensin 1-3 (HNP1-3) in the serum and induced sputum in patients with chronic obstructive pulmonary disease (COPD) and therefore to investigate the possible roles of HNP1-3 in COPD.
Methods: Thirty patients with acute exacerbation of COPD, 21 patients with stable COPD, and 22 healthy subjects were recruited. The concentrations of HNP1-3 and interleukin-8 (IL-8) in serum and induced sputum were measured by enzyme-linked immunosorbent assay (ELISA). The correlations among HNP1-3, neutrophils, IL-8, and lung functions were investigated. The data were analyzed using a statistical software package (SPSS 11.5). Variables were compared with One-Way ANOVA or Chi-square test. The correlations between variables were analyzed using Pearson's correlation coefficient or Spearman correlation coefficient.
Results: The sputum HNP1-3 level was significantly higher in AECOPD patients [9,652(4,272 -12,576) ng/L] than in healthy subjects [4,194 (700 -10,505) ng/L, chi2 =7.53, P <0.01] and in stable COPD patients [7,011(6,658 -7,319) ng/L, chi2 = 10.24, P <0.01]. There was significant difference among the three groups (chi2 =7.31, P <0.05). There was no significant difference in the serum HNP1-3 level among the three groups: AECOPD group [51(39 - 173) ng/L], stable COPD group [135(113 - 241) ng/L], healthy subjects group [130(13 - 160) ng/ L], chi2 = 5.75, P > 0.05. The sputum HNP1-3 level was positively correlated with the number, percentage of sputum neutrophils, and sputum IL-8 level (r = 0.29 to 0.53, respectively P <0.01). The sputum HNP1-3 level was negatively correlated with FEV1/predicted values, FEV1/FVC, and PaO2 (r= -0.33 to -0.44, respectively P <0.01).
Conclusions: HNP1-3 may be involved in the pathogenesis of airway inflammation in COPD. Sputum HNP1-3 may be a noninvasive marker of severity of COPD.