A comparative study of sTREM-1, IL-6 and IL-13 concentration in bronchoalveolar lavage fluid in asthma and COPD: A preliminary study

Background. Soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) is a cell-surface receptor presented on neutrophils, macrophages and monocytes. Elevated sTREM-1 levels are a marker of acute microbial infections, and have also been reported in chronic lung diseases. IL-6 and IL-13 are effective markers in distinguishing these diseases. IL-6 has been shown to play an important role in chronic obstructive pulmonary disease (COPD), while IL-13 is described as one of the key mediators of allergic asthma. Objectives. The aim of the study was to evaluate the level of sTREM-1 in bronchoalveolar lavage fluid (BALF) from stable mild-to-moderate asthma and COPD patients and to compare the utility of BALF sTREM-1 measurements in asthma/COPD differentiation with those of IL-6 and IL-13. Material and methods. The concentration of sTREM-1, IL-6 and IL-13 was evaluated by ELISA in the BALF of stable mild-to-moderate asthma and COPD patients. Results. There were no significant differences in BALF sTREM-1 levels between asthma and COPD patients (52.5 pg/mL for asthma vs 73.4 pg/mL for COPD, p = 0.492), in contrast to the differences in the IL6/IL13 ratio (0.68 in COPD, 0.22 in asthma, p = 0.043). Conclusions. The study showed that BALF sTREM-1 levels do not discriminate between mild-to-moderate asthma and COPD. In contrast, the IL-6/IL-13 ratio measured in BALF effectively differentiated these two diseases in their stable state. These results suggest that the most important marker of inflammation in mild-to-moderate obstructive lung disease is not microbiology-dependent.