Analysis of systemic biomarkers in COPD patients.

The finding that alphal-antitrypsin (AAT) deficiency, PiZZ, a well-established genetic risk factor for COPD, is related to high levels of circulating AAT polymers, prompted us to measure serum levels of such polymers and selected markers of inflammation in age- and gender-matched patients with stable COPD and control subjects with and without severe AAT deficiency, and to assess their relationship with each other and with the genetic AAT-variant. We found that COPD individuals (n= 20), independent of AAT-variant, had significantly higher serum levels of AAT and its polymers, MMP-9, sICAM-1, VEGF and sE-selectin than controls (n=30). Subjects with PiZZ COPD (n= 10) showed significantly elevated serum levels of AAT-polymers, sE-selectin and sICAM-1, while patients with PiMM COPD (n= 10) showed higher levels of MMP-9, VEGF, IL-8 and MCP-1 than controls. By using factor analysis we were able to split the analysed biomarkers into two independent components: the first containing MMP-9, MCP-1, IL-8 and VEGF and the second-AAT and its polymers and sE-selectin. The result from the binomial logistic regression showed that 95.2 percent of the control individuals and 94.7 percent of the COPD patients can be correctly classified on the basis of the measured serum biomarkers. These observations highlight the importance of the finding sets of biomolecules, which could offer new strategies for the diagnosis of COPD and may have value for monitoring progression of COPD.