Lung Surfactant Proteins A (SP-A) and D (SP-D) in Chronic Obstructive Pulmonary Disease (COPD)

Abstract

Introduction:The biomarkers used in COPD are many, but studies of last decades are focused on the pulmonary surfactant, which plays a crucial role in normal lung function.

Aim: Evaluation of the levels of SP-A, SP-D and other markers in patients with SPOK and their relation to inflammation and smoking.

Material :We studied 118 patients with COPD . 10 cases were in stage B, 24 cases in stage C and 84 cases in stage D; 113 males and 5 females , mean age 69 ± 8 years and 70 ± 8 years respectively; Methodology: The SP-A and SP-D levels were measured on admission during acute exacerbation and in the day of discharge from hospital in remission of disease. We included a healthy control group.

Results: In the healthy control group mean SP-A = 22.2 +/- 16.3 ng / ml and mean SP-D=90 +/- 36.8 ng / ml . In our study group ,on admission we found mean SP-A levels 46.8 + -35.2ng / ml and SP-D 175 +/- 99 ng / ml. In COPD Stage B mean SP-A was 33.78 +/- 19.7 ng / ml, Stage C 40.7 +/- 19.5ng / ml and stage D 50.2 +/- 39 ng / ml (p = 0.0001). Mean SP-D at Stage B was 168.3 +/- 121ng / ml, Stage C 160 +/- 78 ng / ml, and Stage D 181 +/- 102ng / ml (p = 0.0001).On the last day(remission) mean SP-A 38+ /23.5ng/ml and mean SP-D 147 +/- 91 ng / ml. In COPD Stage B mean SP-A was 42.7 +/- 26.2 ng / ml, Stage C 33 +/- 15.6ng / ml and stage D 38.5 +/- 25 ng / ml (p = 0.003). Mean SP-D at Stage B was 196 +/- 157ng / ml, Stage C 130 +/- 53 ng / ml, and Stage D 137 +/- 81ng / ml (p = 0.002). In exacerbation period smoking status has significant correlations with all biomarkers presented with the Spearman coefficient: SP-A( R_s = 0.249, p = 0.002); SP-D( R_s = 0.264 p = 0.001), IL6( R_s = 0.255, p = 0.002) and CRP ( R_s = 0.231, p = 0.004). In remission state smoking has significant positive correlation with SP-D (R_s = 0.282, p = 0.002) and SP-A (R_s = 0.273, p = 0.003) .In both evaluations the mean values of SP-A and SP-D were significantly higher in smokers compared to nonsmokers (p<0.05). Levels of IL6 measured in first day were significantly higher in smokers  p=0.025, mean CRP levels had no significant diffierencies between  two groups.

Conclusion: SP-A and SP-D levels were higher in COPD patients compared to healthy control group. Their level were significantly higher AECOPD than in stable state of COPD and they correlated with the gravity of the disease. In remission state SP-A and SP-D levels ​​ reflects better the gravity of COPD. SP-A and SP-D levels are better related with smoking state and their levels are more increased in smokers .

Keywords: COPD, acute exacerbation of COPD (AECOPD), SP-A and SP-D