Molecular mechanisms of inflammation during exacerbations of chronic obstructive pulmonary disease

Exacerbations of chronic obstructive pulmonary disease (COPD) are characterised by an inflammatory and systemic response that persists for some time after their clinical resolution. The mechanisms of this inflammatory process are not well known.

To explore the inflammatory changes and possible mechanisms during COPD exacerbation.

We determined the inflammatory cell concentrations in blood and sputum, nitric oxide in exhaled air (FeNO), C-reactive protein (CRP) in plasma, cytokines (IL-6, 8, 1β, 10, 12, TNF-α) and SLPI (leukocyte protease inhibitor) and total antioxidant status (TAS) in blood and sputum, the activity of nuclear kappa B factor (NF-κ B) and of the histone deacetylase enzyme (HDAC) in 17 patients during COPD exacerbation and in stable phase, as well as in 17 smoker and 11 non-smoker controls.

COPD exacerbations are characterised by high levels of FeNO (p<0.05), plasma CRP (p<0.001) and IL-8, IL-1B, IL-10 in sputum (p<0.05) greater activation of NF-κ appaB in sputum macrophages compared with stable COPD and controls. During the stable phase, there continue to be high levels of oxidative stress, SLPI, IL-8, IL-6 and TNF-alfa, with no observed changes in either HDAC activity or in the amount of neutrophils in sputum, despite presenting a significant improvement (p<0.05) in lung function.

Changes were observed in different pulmonary and systemic inflammatory markers during COPD exacerbation, which did not completely resolve during stable phase. However, current treatment does not allow for HDAC activity to be modified, which limits its anti-inflammatory effects.