Measures of lung function and their relationship with advanced glycation end-products

Advanced glycation end-products (AGEs) have been implicated in the pathophysiology of chronic obstructive pulmonary disease (COPD). However, the association between AGE accumulation in the skin measured by skin autofluorescence (SAF) and lung function in healthy subjects has not been explored in detail. We use a population-based study of 50-64-year-olds to assess spirometry, diffusing capacity of the lung for carbon monoxide (D _LCO) and impulse oscillometry (IOS) in relation to SAF.

Participants with information on SAF, lung function and potential confounding variables were included from the Swedish Cardiopulmonary Bioimage Study (SCAPIS) cohort (spirometry, n=4111; D _LCO, n=3889; IOS, n=3970). Linear regression was used to assess changes in lung function (as measured by spirometry (forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC) and FEV₁/FVC), D _LCO and IOS (resistance measured at 5 (R ₅) and 20 Hz (R ₂₀), R ₅-R ₂₀, area of reactance, reactance measured at 5 Hz (X- ₅), and resonant frequency)) by a 1-sd increase in SAF.

FEV₁, FVC and D _LCO were significantly and inversely associated with SAF after adjustment for potential confounding factors (per 1-sd increase in SAF: FEV₁ -0.03 L (95% CI -0.04- -0.02 L), p<0.001; FVC -0.03 L (95% CI -0.05- -0.02 L), p<0.001; D _LCO -0.07 mmol·min^-1·kPa^-1 (95% CI -0.11- -0.03 mmol·min^-1·kPa^-1), p<0.001). This association was also found in nonsmokers and in non-COPD subjects. Pulmonary reactance (X ₅) but not pulmonary resistance (R ₅, R ₂₀ and R ₅-R ₂₀) was significantly associated with SAF (per 1-sd increase in SAF: X ₅ -0.001 kPa·L^-1·s (95% CI -0.003-0.00 kPa·L^-1·s), p=0.042), which was mirrored in non-COPD patients but not in current nonsmokers.

AGE accumulation, as measured by SAF, is significantly associated with lung function decrements indicative of changes in the lung parenchyma.