Increased serum levels of HSP27 as a marker for incipient chronic obstructive pulmonary disease in young smokers.

BACKGROUND: Although chronic obstructive pulmonary disease (COPD) is amongst the leading causes of morbidity and mortality, no biomarkers for its early detection are known. We have recently demonstrated that COPD is accompanied by elevated serum heat shock protein (HSP) 27 levels as compared to a control population. OBJECTIVES: In an open prospective study, we investigated whether elevated HSP27 levels are associated with the early radiological signs of COPD, i.e., air trapping (AT), emphysema (E) and impaired lung function. METHODS: In total, 120 apparently healthy smokers underwent lung function testing and serum sampling. Serum levels of HSP27, phospho-HSP27, CXCR2 chemokines and proteins related to inflammation, tissue remodeling and apoptosis were evaluated by ELISA. Of these 120 subjects, 94 voluntarily underwent a high-resolution computed tomography scan. RESULTS: AT or AT and E were detected in 57.45%. Subjects with AT and E (n = 23) showed significantly higher HSP27 levels than those without any pathology [i.e., nothing abnormal detected (NAD)] (4,618 +/- 1,677 vs. 3,282 +/- 1,607 pg/ml; p = 0.0081). In a univariate logistic regression model including NAD and AT and E, the area under the curve of HSP27 in the receiver-operating-characteristic curve was 0.724, (0.594­0.854, 95% CI; p = 0.0033). Interestingly, proinflammatory IL-8 was elevated in those subjects with evidence of AT and E compared to those with AT and NAD. Lung function did not correlate with increased HSP27 levels or pathological radiological findings. CONCLUSIONS: HSP27 serum levels correlated with the early radiological signs of COPD, whereas lung function did not match with radiological findings or HSP27 serum levels. Serum HSP27 levels may serve as a potential marker to identify the early signs of COPD independent of lung function in young smokers.