Airway biomarkers of the oxidant burden in asthma and chronic obstructive pulmonary disease: Current and future perspectives

Abstract

Abstract:The pathogenesis of asthma and chronic obstructive pulmonary disease (COPD) has been claimed to be attributable to increased systemic and local oxidative stress. Detection of the oxidant burden and evaluation of their progression and phenotypes by oxidant biomarkers have proved challenging and diffi cult. A large number of asthmatics are cigarette smokers and smoke itself contains oxidants complicating further the use of oxidant biomarkers. One of the most widely used oxidant markers in asthma is exhaled nitric oxide (NO), which plays an important role in the pathogenesis of asthma and disease monitoring. Another oxidant marker that has been widely investigated in COPD is 8-isoprostane, but it is probably not capable of differentiating asthma from COPD, or even sensitive in the early assessment of these diseases. None of the current biomarkers have been shown to be better than exhaled NO in asthma. There is a need to identify new biomarkers for obstructive airway diseases, especially their differential diagnosis. A comprehensive evaluation of oxidant markers and their combinations will be presented in this review. In brief, it seems that additional analyses utilizing powerful tools such as genomics, metabolomics, lipidomics, and proteomics will be required to improve the specifi city and sensitivity of the next generation of biomarkers. Keywords: sputum, condensate, smoking, nitric oxide, 8-isoprostane, biomarker Asthma and chronic obstructive pulmonary disease (COPD) are diseases with different physiological and anatomical features. However, a signifi cant number of patients suffering from these diseases exhibit symptoms and signs which are associated with both conditions. Markers of the elevated oxidant burden have been detected in both of these disorders. This degree of overlap between asthma and COPD has proved to be especially important in smoking asthmatics, patients who have often been excluded from asthma trials and investigations. Oxidant markers are under intensive investigation as ways of assuring the early detection and monitoring of asthma and COPD, for the differentiation of the disease from the condition of "healthy smokers", and also for the evaluation of the COPD phenotypes and their progression. This review will critically review potential markers that refl ect oxidative stress in the airways of patients with asthma and COPD in exhaled air, exhaled breath condensate (EBC) and induced sputum. In addition, markers in bronchoalveolar lavage (BAL) will also be briefl y surveyed, even though the technique, ie, fi breoptic bronchoscopy is an invasive technique used in the investigation of lung infl ammation and the evaluation of the oxidant burden. In this review, we will also discuss the pros and cons of various noninvasive biological samples for assessing the oxidant burden in the airways, and then speculate on the possibilities of using the existing and new oxidant markers,

Ageing and long-term smoking affects KL-6 levels in the lung, induced sputum and plasma

“…Several markers of oxidant burden and inflammation are elevated in smokers who have not developed obstruction/COPD [ 6 - 10 ]. However, these markers are not specific for smoking or COPD [ 10 ].…”

“…Several markers of oxidant burden and inflammation are elevated in smokers who have not developed obstruction/COPD [ 6 - 10 ]. However, these markers are not specific for smoking or COPD [ 10 ]. The epithelial lining fluid and mucins provide the first line of defense in the lung [ 11 - 14 ].…”

Elevation of sputum matrix metalloproteinase-9 persists up to 6 months after smoking cessation: a research study

“…Induced sputum (IS) collection is a non-invasive method for assessment of airway inflammation in the airways. In the future, useful biomarkers may also be identified in IS, to permit accurate determination of the many phenotypes of smoking-related diseases [ 18 , 19 ].…”

Airway oxidative stress in chronic cough

“…As mentioned in the introduction, there is solid experimental evidence suggesting that airway oxidative stress might be involved in chronic cough with many ROS and RNS and their metabolites being capable to affect the function of sensory bronchopulmonary C-fibres [ 6 - 8 , 10 ]. The sources of ROS and RNS in the airways can be both endogenous and exogenous [ 42 ]. The exogenous sources of ROS and RNS are various environmental pollutants, especially airborne particulate matter and cigarette smoke [ 43 - 46 ].…”