Non-invasive biomarkers and pulmonary function in smokers

Area of Science:

• Pulmonary Medicine
• Biomarker Research
• Respiratory Physiology

Background:

• Limited data exists on non-invasive biomarker measurement, reproducibility, and interrelationships in smokers.
• Understanding these markers is crucial for assessing smoking-related respiratory health.

Purpose of the Study:

• To compare non-invasive biomarkers in smokers versus non-smokers.
• To assess the relationships between various respiratory measurements.
• To evaluate the within-subject reproducibility of exhaled breath condensate (EBC) biomarkers in smokers.

Main Methods:

• Compared EBC leukotriene B4 (LTB4) and 8-isoprostane, exhaled nitric oxide, induced sputum, spirometry, plethysmography, impulse oscillometry, and methacholine reactivity.
• Included 18 smokers and 10 non-smokers.
• Assessed biomarker relationships and EBC reproducibility in smokers.

Main Results:

• Smokers exhibited significantly lower MMEF % predicted, FEV1/FVC, and specific conductance, alongside higher resonant frequency and EBC 8-isoprostane compared to non-smokers.
• Smokers showed predominant sputum neutrophilia and a subgroup had airway acidification.
• EBC 8-isoprostane correlated with EBC LTB4; sputum IL-8 correlated with neutrophil count and EBC pH.

Conclusions:

• Smokers demonstrate small airway dysfunction, increased airway resistance, reduced lung compliance, airway neutrophilia, and oxidative stress.
• While EBC measurements showed no significant group differences upon repetition, individual variability was noted.
• Non-invasive biomarkers reflect key pathological changes in smokers' airways.