Correlation analysis of surfactant protein A and surfactant protein D with lung function in exhaled breath condensate from lung cancer patients with and without COPD

pulmonary surfactant protein D (SP-D) are associated with the pathogenesis of chronic obstructive pulmonary disease (COPD). The aim of the present study was to determine the correlation between SP-A, SP-D and lung function in patients with COPD. A total of 60 patients with lung cancer undergoing unilateral lobectomy were selected and divided into three groups, including a non-COPD group (n=20), a COPD treatment group (n=20) and a COPD control group (n=20). The levels of SP-A and SP-D were detected in the exhaled breath condensate (EBC) using ELISA analysis. Tissue samples were obtained during lobectomy via resection of the adjacent lung tissues, located >5 cm from the nodule. Immunohistochemistry and reverse transcription-quantitative polymerase chain reaction analysis was performed. The proportion of SP-A(+) alveolar type II (ATII) cells and the mRNA levels of SP-A and SP-D in lung tissue were measured. In addition, the correlation between SP-A and SP-D in EBC, SP-A and SP-D mRNA in lung tissue, forced expiratory volume in 1 sec (FEV1) and the ratio of SP-A(+) ATII, was evaluated. The expression levels of SP-A and SP-D were significantly increased in patients of the non-COPD group compared with the other two groups (P<0.05). In addition, the expression levels of SP-A were positively correlated with FEV1 and the ratio of SP-A(+) ATII (P<0.05). The expression levels of SP-D exhibited no correlation with FEV1 and ratio of SP-A(+) ATII (P>0.05). The results of the present study indicated that the SP-A and SP-D levels in EBC were correlated with lung function, which contributed to COPD diagnosis. Future studies are required to further investigate the results of the present study.