Levels of soluble triggering receptor expressed on myeloid cells 1 in infectious exacerbations of chronic obstructive pulmonary disease.

BACKGROUND

Soluble triggering receptor expressed on myeloid cells 1 (sTREM-1) is an activating receptor on inflammatory cells upregulated by microbial products. Elevated levels of sTREM-1 have been associated with the diagnosis and prognosis of patients with sepsis, severe pneumonia and chronic obstructive pulmonary disease (COPD).

OBJECTIVES

The aim of this study was to define the role of sTREM-1 in acute exacerbations of COPD (AE-COPD) and to investigate the ability of sTREM-1 to differentiate between infectious triggers of AE-COPD.

METHODS

Smokers without COPD (SM), patients with stable COPD (sCOPD) and patients with AE-COPD were prospectively recruited. sTREM-1 levels were determined by ELISA in serum. Potentially pathogenic bacteria were analyzed by sputum culture, and polymerase chain reaction was used to determine the presence of respiratory viruses.

RESULTS

One hundred and ninety-five subjects were included: 64 sCOPD patients, 118 AE-COPD patients and 13 SM. In 62 (52.6%) AE-COPD patients, a respiratory pathogen was detected. Serum levels of sTREM-1 were barely detectable in SM but were significantly increased in patients with sCOPD [97.5 (interquartile value 76.6) pg/ml] and AE-COPD [110.9 (98.5) pg/ml; p<0.001]. There was no significant difference in sTREM-1 between sCOPD and AE-COPD (p=0.277). However, in AE-COPD, sTREM-1 was significantly lower in patients with virus detection [87.5 (97.3) pg/ml] compared to those without [120.3 (99.7) pg/ml; p=0.015]. No difference was found in AE-COPD patients with or without bacterial detection.

CONCLUSIONS

The present study shows an increase in sTREM-1 in patients with COPD compared to SM but not in AE-COPD compared to sCOPD. Viral exacerbations showed significantly lower sTREM-1 levels than non-viral exacerbations.