The expression and significance of Krebs von den lungen-6, pulmonary surfactant protein-A, D, interleukin-6 in patients with connective tissue diseases interstitial pulmonary disease

Abstract

Objective To determine the levels and significance of Krebs von den lungen-6 (KL-6) , pulmonary surfactant protein A (SP-A), SP-D and interleukin (IL)-6 in patients with connective tissue disease interstitial lung disease (CTD-ILD). Methods The serum KL-6, SP-A, SP-D and IL-6 in all subjects were detected and the imaging and pulmonary function were recorded t test, χ2 test, non-parametric test, ANOVA and correlation analysis were used for data analysis. Results ① The levels of serum KL-6, SP-A, SP-D, IL-6 in the CTD-ILD group [551.4(428.2, 883.5) U/ml, 938.4 (435.2, 2324.7) pg/ml, 90.7(80.7, 100.3) ng/ml and 30.4 (22.9, 41.7) pg/ml; P all<0.05] was significantly higher than that in the CTD group [192.9(139.2, 266.2) U/ml; 458.0 (372.6, 529.0) pg/ml; 80.0(71.2, 98.3) ng/ml; 18.6(4.9, 31.0) pg/ml, Z=-5.383, -3.76, -2.123,-3.903, P all <0.05]; and higher than healthy controls (n=30) [183.2(141.9, 216.6) U/ml; 229.0(162.0, 248.0) pg/ml; 50.8(26.1, 96.4) ng/ml; 7.1(3.7, 8.7) pg/ml, Z=-5.801, -8.13, 2.272, 3.266; P all<0.05]. ② The levels of KL-6 in pulmonary HRCT for active ILD group was significantly higher than the non-active ILD group [998.5(640.3, 1293.3) U/ml vs 565.0(434.0, 799.5) U/ml, Z=2.182, P=0.023], there was no statistical difference in the levels of SP-A, SP-D, IL-6 between the 2 groups. ③ Spearman correlation analysis showed that KL-6 was negatively correlated with forced vital capacity (FVC%); SP-D, IL-6 and diffusing capacity of carbon monoxide (DLCO%). ④ Logistic multiple regression analysis showed that KL-6 [OR=1.017, P=0.002, 95%CI(1.006, 1.028)], SP-A [OR=1.023, P=0.009, 95%CI(1.006, 1.041)], SP-D[OR=1.175, P=0.009, 95%CI(1.075, 1.264)], IL-6[OR=1.213, P=0.001, 95%CI(1.088, 1.354)] were the risk factors for ILD. Conclusion Serum KL-6, SP-A, SP-D and IL-6 are significantly increased and correlate with CTD-ILD. KL-6 is related to the pulmonary inflammatory disease and vital capacity, while SP-D and IL-6 are related to diffusion function. Key words: Connective tissue diseases; Lung diseases, interstitial; Pulmonary surfactant-associated proteins; Krebs von den lungen-6