Relationship between serum levels of endogenous secretory RAGE and blood pressure in male nondiabetic patients with obstructive sleep apnea

Cardiovascular and metabolic effects of a mandibular advancement device and continuous positive airway pressure in moderate obstructive sleep apnea: a randomized controlled trial

STUDY OBJECTIVES

It has been suggested that treatment for obstructive sleep apnea (OSA) reduces cardiovascular risk. So far, knowledge is limited about the difference in the reduction of this risk between mandibular advancement device (MAD) and continuous positive airway pressure (CPAP) therapy. The aim of this study was to compare the cardiovascular effects of MAD versus CPAP therapy in patients with moderate OSA.

METHODS

Patients with an apnea-hypopnea index (AHI) of 15-30 events/h were randomized to either MAD or CPAP therapy. At baseline and after 12-months follow-up, 24-hour ambulant blood pressure measurements (ABPM) and laboratory measurements were performed. ABPM consisted of 24-hour, daytime and night-time systolic (SBP) and diastolic blood pressure (DBP), and heart rate (HR) measurements. Laboratory measurements consisted of serum lipid values, creatinine, high-sensitivity c-reactive protein, plasma glucose, hemoglobin A1c (HbA1c), proinflammatory cytokines, soluble receptor for advanced glycation end products (sRAGE), chemokines and adhesion molecules.

RESULTS

Of the 85 randomized patients with moderate OSA, data were available for 54 patients (n=24 MAD, n=30 CPAP) at 12-month follow-up and showed that AHI significantly decreased with either therapy. In the MAD group, sRAGE and HbA1c were significantly higher after 12 months follow-up compared to baseline. No significant changes were found between MAD and CPAP treatment for all outcomes.

CONCLUSIONS

Treatment of patients with moderate OSA with either MAD or CPAP therapy had no profound effects on major cardiovascular risk factors after 12-months.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Title: MRA Therapy Versus CPAP Therapy in Moderate OSAS; Identifier: NCT01588275; URL: https://clinicaltrials.gov/ct2/show/NCT01588275.

The relationship between endogenous secretory RAGE and cardiac autonomic function in prediabetes

AIMS

The putative protective role of esRAGE for cardiac autonomic function (CAF) remains unclear. To address this question, the present study has assessed the relationship of serum AGEs, sRAGE and esRAGE, and tissue AGEs with CAF in a high-risk population without diabetes.

MATERIAL AND METHODS

This study enrolled 48 subjects of mean age 52.7 ± 11.2 years and mean BMI 28.4 ± 6.3 kg/m² , divided into two groups according to glucose tolerance: 16 with normal glucose tolerance (NGT) and 24 with prediabetes. A standard oral glucose tolerance test (OGTT) was performed. The glucose tolerance was defined according to 2006 WHO criteria. Fasting, 120-minutes glucose, lipids, creatinine, and HbA1c were measured. eGFR was calculated (CKD-EPI). Fasting, 120-minutes insulin (ECLIA method), advanced glycation end products (AGEs), plasma-soluble receptor for AGE (sRAGE), and endogenous secreted isoform of the receptor for AGE (esRAGE), (ELISA method) were assessed. HOMA-IR was calculated. Tissue AGEs were assessed by skin autofluorescence (AGE-Reader, DiagnOpticsTM). CAF was evaluated with ANX 3.0 autonomic nervous-monitoring system (ANSAR), applying deep breathing, Valsalva, and standing.

RESULTS

There was a significant decline in CAF in prediabetes in comparison with NGT. Serum and tissue AGEs, sRAGE, and esRAGE levels were similar between groups. On the matrix analysis, both sympathetic and parasympathetic activities at baseline and after standing and sympathetic tone during Valsalva were positively related to esRAGE in prediabetes. Multivariate regression analysis showed that esRAGE is an independent contributor to sympathetic, parasympathetic, and total autonomic tone in prediabetes accounting for about 28%, 34%, and 35% of their variances, respectively.

CONCLUSION

Our results have demonstrated that CAF is decreased in prediabetes. esRAGE, but not sRAGE, is reciprocally related to CAF, probably opposing the negative effects of glycation.

Oxidative Stress Markers among Obstructive Sleep Apnea Patients

Obstructive sleep apnea (OSA) is a chronic respiratory disorder, which can be present in up to 50% of the population, depending on the country. OSA is characterized by recurrent episodes of partial or complete obstruction of the upper airways with consistent movement of the respiratory musculature during sleep. Apneas and hypopneas can lead to a decrease in oxygen saturation, an increase in carbon dioxide in the blood, and subsequent arousals and sleep fragmentation caused by repetitive activation of the central nervous system. As a consequence, intermittent hypoxemia and consequent reoxygenation result in the production of reactive oxygen species, leading to systematic oxidative stress, which is postulated to be a key mechanism of endothelial dysfunction and increased risk for cardiovascular disorders in patients with OSA. In this review, various biomarkers of oxidative stress, including high-sensitivity C-reactive protein, pregnancy-associated plasma protein-A, superoxide dismutase, cell-free DNA, 8-hydroxy-2-deoxyguanosine, advanced oxidation protein products, lipid peroxidation products, receptor for advanced glycation end-products, and thioredoxin are discussed. Biomarkers of oxidative stress have the potential to be used to assess disease severity and treatment response. Continuous positive airway pressure (CPAP) is one of the most common noninvasive treatments for OSA; it keeps the upper airways open during sleep. This reduces episodes of intermittent hypoxia, reoxygenation, and arousal at night. CPAP has been shown to have anti-inflammatory properties and decrease oxidative stress. The administration of certain compounds, like vitamins A, C, and E as well as N-acetylcysteine and allopurinol, can decrease oxidative stress markers. However, their role in the treatment of OSA remains unclear.

Serum AGEs and sRAGE levels are not related to vascular complications in patients with prediabetes

BACKGROUND

While hyperglycemia has a key role in the pathogenesis of microvascular complications of diabetes, it is just one of the many factors contributing to macrovascular damage. The aim of the present study is to investigate the link between serum pentosidine and sRAGE levels and vascular complications in patients with prediabetes compared to normal glucose tolerance controls with obesity.

METHODS

In this study were included 76 patients with mean age 50.7 ± 10.7 years, divided into two age and BMI-matched groups - group 1 with obesity without glycemic disturbances (n = 38) and group 2 with obesity and prediabetes (n = 38).

RESULTS

There was no significant difference in pentosidine and sRAGE levels between patients with obesity and prediabetes. Patients with hypertension had lower levels of sRAGE compared to nonhypertensive subjects. sRAGE showed a weak negative correlation to blood glucose on 60th min of OGTT and HOMA index. There was no correlation between sRAGE and pentosidine levels and the markers of micro- and macrovascular complications. There was no difference in sRAGE and pentosidine levels between patients with and without endothelial dysfunction.

CONCLUSIONS

sRAGE and pentosidine levels are similar in patients with obesity with and without prediabetes and do not correlate to the markers of micro- and macrovascular complications.