Chronic tobacco smokers have an increased rate of chronic obstructive pulmonary disease (COPD), chronic bronchitis and bacterial lung infections and these disorders respond poorly to available therapies. Previous research has shown that smokers with lung disease have an accumulation of a type of white blood cell, called neutrophils, in their airways. Dr Karlhans Fru Che and Professor Anders Lindén at Karolinska Institutet led a team of researchers from universities in Sweden and Finland to investigate why this is the case.
May represent a novel mechanism
The researchers found that an immune signalling protein called IL-26 (interleukin-26) is present at high levels in the lungs of these patients. IL-26 levels were higher than normal in the chronic smokers, regardless of whether they had clinically stable COPD. Those who had chronic bronchitis or growth of bacteria had higher levels of IL-26 than those who did not. Moreover, the chronic smokers with exacerbations of COPD had higher levels of IL-26 than those with clinically stable COPD. Upregulation of IL-26 in the airways in response to tobacco smoke may represent a novel mechanism by which neutrophil recruitment to the lung is regulated, according to the researchers.
“By showing that IL-26 is involved in the excessive mobilization of neutrophils in chronic smokers with or without COPD and chronic bronchitis, we strengthen the evidence that this cytokine bears potential as a target for monitoring of and therapeutic intervention in airway disorders characterised by neutrophilic inflammation,” says Dr Karlhans Fru Che at the Institute of Environmental Medicine, Karolinska Institutet, lead author on the study.
Source: Karolinska Institutet