Serum surfactant protein D: biomarker of chronic obstructive pulmonary disease.
BACKGROUND
Surfactant protein D (SP-D) is a lung-specific protein proposed to predict clinical outcomes in patients with chronic obstructive pulmonary disease (COPD). However, the changes in serum SP-D during acute exacerbation (AECOPD) episodes and the relationship of serum SP-D with the overall severity of the disease in stable COPD (SCOPD) remain unclear.


METHODS
Serum SP-D levels were analyzed in three groups, including AECOPD (n=40), SCOPD (n=71), and controls (n=60). In AECOPD group, serum SP-D levels were determined at 1, 5, 14, and 30 days post-exacerbation. In SCOPD group, BODE (body mass index, airflow obstruction, dyspnea, exercise capacity) index was evaluated for severity assessment.


RESULTS
Serum SP-D levels were sequentially elevated from the controls to the SCOPD, and then to the AECOPD (p< 0.001). During an AECOPD episode, the raised serum SP-D levels subsided at day 5 (p> 0.05), fell markedly at day 14 (p< 0.001), and continued to decline at day 30 (p< 0.001). Among patients with SCOPD, serum SP-D levels correlated positively with the BODE index (p< 0.01).


CONCLUSIONS
The longitudinal changes in serum SP-D levels during an AECOPD episode suggest that SP-D may be a potential systemic biomarker for COPD exacerbation. The correlation of serum SP-D levels with the BODE index suggests that circulating SP-Ds can reflect the overall severity of SCOPD.
State Key Lab of the Respiratory Disease, Guangzhou Institute of Respiratory Disease, First Affiliated Hospital of Guangzhou Medical College, Guangdong, China.
Chun-Rong
CR
Ju
Wei
W
Liu
Rong-Chang
RC
Chen
D000368:Aged; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D002097:C-Reactive Protein / Q000378:metabolism; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood*; D037663:Pulmonary Surfactant-Associated Protein D / Q000097:blood*; D012720:Severity of Illness Index; D013147:Spirometry
D015415:Biomarkers; D037663:Pulmonary Surfactant-Associated Protein D; D002097:C-Reactive Protein