Abstract
Background: In COPD airflow limitation and hyperinflation leads to relative hypoxia in the affected alveoli and results in hypoxaemia.Extracellular heat shock protein 72 (eHsp72) plays pivotal role in the stress responses and immune regulation.Role of alveolar oxygen tension, eHsp72 and their relationship in the pathogenesis of COPD are not fully understood.
Methods: Healthy volunteers (C,n=10), normoxaemic (N,n=11) and hypoxaemic (H,n=10) COPD patients were enrolled into clinical examinations, including lung function test, blood gas analysis, 6 minute walk test and quality of life tests (QLT).Mass spectrometry was used to measure exhaled O2 (PexO2).Serum of eHsp72 was assessed by ELISA.
Results: PexO2 measured on the level of residual volume was significantly lower in group H compared to group C (C:90,95±3,59 vs. H:75,97±4,27 Hgmm,p<0,01), but it did not show difference in group N. PexO2 correlated to airway obstruction (forced exspiratory volume in one second: FEV1(%):r=0,53,p=0,002; forced expiratory flow: FEF25-75(%):r=0,52,p=0,003). QLT results were worse in group H compared to group N nearly the same values of FEV1 (C:39,90±4,12 vs. H:34,53±5,60 reference%). The level of eHsp72 significantly decreased in N and H COPD groups compared to C (C:3,89±0,53ng/ml vs. N:2,88±0,31ng/ml, p<0,05; vs. H:2,71±0,13ng/ml, p<0,001) and positively correlated with airway obstruction (FEV1(%):r=0,38,p=0,05), but did not correlated with PexO2.
Conclusions: Airway obstruction leads to decreased alveolar oxygen tension in hypoxaemic COPD patients which correlates with hyperinflation and worse quality of life indicators. Additionally eHsp72 could be a promising biomarker in COPD assessment.
- Copyright ©ERS 2015