EFFECTS OF AGE AND SEX ON PLASMA ADRENOMEDULLIN LEVELS IN PATIENTS WITH OBSTRUCTIVE SLEEP APNEA SYNDROME

Sleep duration is associated with protein biomarkers for cardiometabolic health: A large-scale population study

Sleep problems and short sleep duration have been linked to adverse health effects, such as cardiovascular disease and diabetes, but the mechanisms are not fully understood. Finding biomarkers could explain mechanistic pathways and help in understanding relationships between sleep and cardiometabolic health. The aim was to assess if sleep duration and sleep quality affect the cardiometabolic-related protein profile. In total, 242 proteins related to cardiometabolic health were measured in 2,430 plasma samples (male:female ratio 1:1, aged 45-75 years) from the population-based EpiHealth cohort, using a proximity extension assay. The association of self-reported sleep duration and sleep quality with each of the 242 proteins (primary outcome) was assessed with linear regression modelling, adjusting for confounders, and corrected for multiple testing using the false discovery rate (5%). Potential effect modification of age and sex was also tested using an interaction term. We identified U-shaped associations between sleep duration and the plasma levels of the proteins follistatin (more prominent in younger individuals), matrix metallopeptidase 9 (men only), urokinase receptor, adrenomedullin and kidney injury molecule, all previously known to be related to cardiovascular risk. There was no relationship between sleep quality and any of the proteins, after adjustment for confounders. These results give new leads to investigate the potential mechanistic pathways between sleep and cardiometabolic health.

Effect of OSA on hypoxic and inflammatory markers during CPAP withdrawal: Further evidence from three randomized control trials

BACKGROUND AND OBJECTIVE

Obstructive sleep apnoea (OSA) is associated with cardiovascular disease. Intermittent hypoxia, endothelial dysfunction and adipose tissue-mediated inflammation have all been linked to cardiovascular disease in OSA. We therefore explored the effect of OSA on relevant associated blood markers: adrenomedullin (ADM), endocan, endothelin-1 (ET-1), resistin and vascular endothelial growth factor (VEGF).

METHODS

Patients with OSA, established on and compliant with continuous positive airways pressure (CPAP) therapy for >1 year were included from three randomized controlled trials, conducted at two centres. Patients were randomized to either continued therapeutic CPAP or sham CPAP (CPAP withdrawal) for 2 weeks. Blood markers were measured at baseline and at 14 days and the treatment effect between sham CPAP and therapeutic CPAP was analysed.

RESULTS

A total of 109 patients were studied (therapeutic CPAP n = 54, sham CPAP n = 55). Sham CPAP was associated with a return of OSA (between-group difference in oxygen desaturation index (ODI) 36.0/h, 95% CI 29.9-42.2, P < 0.001). Sham CPAP was associated with a reduction in ADM levels at 14 days (-26.0 pg/mL, 95% CI -47.8 to -4.3, P = 0.02), compared to therapeutic CPAP. Return of OSA was not associated with changes in endocan, ET-1, resistin or VEGF.

CONCLUSION

Whilst CPAP withdrawal was associated with return of OSA, it was associated with an unexpected significant reduction in the vasodilator ADM and not with expected increases in hypoxia-induced markers, markers of endothelial function or resistin. We propose that the vascular effects occurring in OSA may be brought about by other mechanisms, perhaps partly through a reduction in ADM.

Adrenomedullin Function in Vascular Endothelial Cells: Insights from Genetic Mouse Models

Adrenomedullin is a highly conserved peptide implicated in a variety of physiological processes ranging from pregnancy and embryonic development to tumor progression. This review highlights past and present studies that have contributed to our current appreciation of the important roles adrenomedullin plays in both normal and disease conditions. We provide a particular emphasis on the functions of adrenomedullin in vascular endothelial cells and how experimental approaches in genetic mouse models have helped to drive the field forward.