Lipopolysaccharide-binding protein levels, obstructive sleep apnea, and depression: A cross-sectional study of adults.

Obstructive sleep apnea (OSA) and depression are highly comorbid. Increased intestinal permeability has been hypothesized to play a role in the pathogenesis of both. The current study aimed to assess the severity of OSA symptoms, comorbid depressive symptoms, and lipopolysaccharide-binding protein (LBP) levels in adult patients being diagnosed for OSA syndrome. The study population consisted of 176 subjects. An apnea-hypopnea index (AHI) ≥ 5/hour was used for the diagnosis of OSA syndrome. Depressive symptoms were assessed with the Beck Depression Inventory-2. LBP levels were measured in the blood serum by enzyme-linked immunosorbent assay (ELISA). Associations between clinical symptom profiles or severity and LBP as an intestinal permeability biomarker marker were tested. LBP levels were not different between patients with different OSA severity, as assessed with AHI or daily sleepiness. Nor were LBP levels different in subjects with different depressiveness severity. Daily sleepiness was weakly positively correlated with depression score, and LBP levels correlated positively with a neutrophils-to-lymphocytes ratio. Finally, LBP levels were not explained by multiple linear regression models, including sleep-related parameter values and depression score. Intestinal permeability, as measured with LBP level, may not explain the comorbidity of depression and daily sleepiness in the course of OSA syndrome.