Circulating KL-6, a biomarker of lung injury, in obstructive sleep apnoea

D J Lederer,A Ishizaka,J Bhattacharya,R C Basner,S Jelic

doi:10.1183/09031936.00150708

D J Lederer, A Ishizaka + Show 3 more

Open Access

https://doi.org/10.1183/09031936.00150708

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Abstract

In obstructive sleep apnoea (OSA), oxidative stress contributes to endothelial dysfunction in the peripheral circulation. In the lung, oxidative stress can lead to alveolar injury. The present authors hypothesised that patients with OSA would have biomarker evidence of increased alveolar wall permeability. Sleep characteristics, brachial artery flow-mediated dilation and plasma KL-6 levels were observed in 11 otherwise healthy patients with OSA and 10 controls. Median (interquartile range) plasma KL-6 levels were higher in patients with OSA compared with controls: 317 (232-506) U.mL(-1) versus 226 (179-257) U.mL(-1), respectively. Higher plasma KL-6 levels were associated with greater time spent asleep with an oxyhaemoglobin saturation <90%, lower nadir saturation, more frequent desaturation of >4% during sleep and lower brachial artery flow-mediated dilation. Adjustment for nadir saturation or flow-mediated dilation attenuated the association between plasma KL-6 levels and OSA. Circulating KL-6 levels are elevated in some patients with obstructive sleep apnoea, possibly reflecting increased alveolar wall permeability.

Highlights

Sleep characteristics, brachial artery flow-mediated dilation and plasma KL-6 levels were observed in 11 otherwise healthy patients with Obstructive sleep apnoea (OSA) and 10 controls
OSA: obstructive sleep apnoea; BMI: body mass index; AHI: apnoea/hypopnoea index; ODI4: number of arterial oxyhaemoglobin desaturation events o4% per hour of sleep; Sp,O2: arterial oxygen saturation measured by pulse oximetry; ESS: Epworth Sleepiness Scale
In the current preliminary study, the authors found that some patients with OSA had elevated circulating levels of KL-6, a marker of increased alveolar wall permeability, compared with age, sex- and BMI-matched controls

Summary

Introduction

Brachial artery flow-mediated dilation and plasma KL-6 levels were observed in 11 otherwise healthy patients with OSA and 10 controls. Higher plasma KL-6 levels were associated with greater time spent asleep with an oxyhaemoglobin saturation ,90%, lower nadir saturation, more frequent desaturation of .4% during sleep and lower brachial artery flow-mediated dilation. Adjustment for nadir saturation or flow-mediated dilation attenuated the association between plasma KL-6 levels and OSA. Circulating KL-6 levels are elevated in some patients with obstructive sleep apnoea, possibly reflecting increased alveolar wall permeability. Received: Accepted after revision: Obstructive sleep apnoea (OSA), a chronic disorder characterised by sleep-related upper airway obstruction [1], is associated with increased oxidative stress, which contributes to endothelial dysfunction in the peripheral circulation [2]. The injurious effects of oxidative stress in the lungs of patients with OSA are largely unknown

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