HDL dysfunction in obstructive sleep apnea

A Machine Learning Prediction Model of Adult Obstructive Sleep Apnea Based on Systematically Evaluated Common Clinical Biochemical Indicators

Objective

Obstructive sleep apnea (OSA) is a common and potentially fatal sleep disorder. The purpose of this study was to construct an objective and easy-to-promote model based on common clinical biochemical indicators and demographic data for OSA screening.

Methods

The study collected the clinical data of patients who were referred to the Sleep Medicine Center of the Second Affiliated Hospital of Fujian Medical University from December 1, 2020, to July 31, 2023, including data for demographics, polysomnography (PSG), and 30 biochemical indicators. Univariate and multivariate analyses were performed to compare the differences between groups, and the Boruta method was used to analyze the importance of the predictors. We selected and compared 10 predictors using 4 machine learning algorithms which were "Gaussian Naive Bayes (GNB)", "Support Vector Machine (SVM)", "K Neighbors Classifier (KNN)", and "Logistic Regression (LR)". Finally, the optimal algorithm was selected to construct the final prediction model.

Results

Among all the predictors of OSA, body mass index (BMI) showed the best predictive efficacy with an area under the receiver operating characteristic curve (AUC) = 0.699; among the predictors of biochemical indicators, triglyceride-glucose (TyG) index represented the best predictive performance (AUC = 0.656). The LR algorithm outperformed the 4 established machine learning (ML) algorithms, with an AUC (F1 score) of 0.794 (0.841), 0.777 (0.827), and 0.732 (0.788) in the training, validation, and testing cohorts, respectively.

Conclusion

We have constructed an efficient OSA screening tool. The introduction of biochemical indicators in ML-based prediction models can provide a reference for clinicians in determining whether patients with suspected OSA need PSG.

Causal relationship between sleep apnea and non-alcoholic fatty liver disease: A Mendelian randomization study

BACKGROUND

Observational studies indicate that sleep apnea is associated with non-alcoholic fatty liver disease (NAFLD) and its related metabolic features, independent of confounding factors including obesity. However, the causal relationships remain to be determined.

METHODS

Univariable and multivariable Mendelian randomization (MR) analyses were performed to investigate the causal relationship between sleep apnea and NAFLD, along with its typical features including liver function, glycemic traits and lipid profiles. Summary-level data for sleep apnea were obtained from the Finngen consortium (33,423 cases and 307,648 controls). Summary-level data for NAFLD were available from a GWAS meta-analysis (8434 cases and 770,180 controls), and data for 12 NAFLD-related features from corresponding published GWASs. The inverse variance weighted (IVW) analysis was employed as the primary statistical method. Bidirectional MR and CAUSE analysis were conducted to avoid reverse causality and false positive findings.

RESULTS

In univariable MR analyses, we found evidence to support a causal effect of genetically predicted sleep apnea on NAFLD (OR = 1.50, 95% CI = 1.18-1.91) and HDL-C (β = -0.045, 95% CI = -0.090 to -0.001). In reverse MR, genetically predicted serum TG was associated with an increased risk of sleep apnea (OR = 1.07, 95% CI = 1.02-1.12), while genetically predicted HDL-C was associated with a decreased risk of sleep apnea (OR = 0.93, 95% CI = 0.89-0.98). After adjusting body mass index or educational attainment, none of these causal associations were retained. However, CAUSE method and MR analyses focusing on lipoprotein subfractions supported a causal effect of sleep apnea on HDL-C and HDL subfractions.

CONCLUSION

This MR study indicated that sleep apnea has no direct causal association with NAFLD, elevated liver enzymes and insulin resistance. Our results showed suggestive inverse associations of genetically predicted sleep apnea on HDL-C and HDL subfractions, indicating that both HDL-C levels and HDL function may be causally implicated in sleep apnea.

Modulation of the Cellular microRNA Landscape: Contribution to the Protective Effects of High-Density Lipoproteins (HDL)

High-density lipoproteins (HDL) play an established role in protecting against cellular dysfunction in a variety of different disease contexts; however, harnessing this therapeutic potential has proved challenging due to the heterogeneous and relative instability of this lipoprotein and its variable cargo molecules. The purpose of this study is to examine the contribution of microRNA (miRNA; miR) sequences, either delivered directly or modulated endogenously, to these protective functions. This narrative review introduces the complex cargo carried by HDL, the protective functions associated with this lipoprotein, and the factors governing biogenesis, export and the uptake of microRNA. The possible mechanisms by which HDL can modulate the cellular miRNA landscape are considered, and the impact of key sequences modified by HDL is explored in diseases such as inflammation and immunity, wound healing, angiogenesis, dyslipidaemia, atherosclerosis and coronary heart disease, potentially offering new routes for therapeutic intervention.

Investigating the Relationship between Obstructive Sleep Apnoea, Inflammation and Cardio-Metabolic Diseases

Obstructive sleep apnoea (OSA) is a prevalent underdiagnosed disorder whose incidence increases with age and weight. Uniquely characterised by frequent breathing interruptions during sleep-known as intermittent hypoxia (IH)-OSA disrupts the circadian rhythm. Patients with OSA have repeated episodes of hypoxia and reoxygenation, leading to systemic consequences. OSA consequences range from apparent symptoms like excessive daytime sleepiness, neurocognitive deterioration and decreased quality of life to pathological complications characterised by elevated biomarkers linked to endocrine-metabolic and cardiovascular changes. OSA is a well-recognized risk factor for cardiovascular and cerebrovascular diseases. Furthermore, OSA is linked to other conditions that worsen cardiovascular outcomes, such as obesity. The relationship between OSA and obesity is complex and reciprocal, involving interaction between biological and lifestyle factors. The pathogenesis of both OSA and obesity involve oxidative stress, inflammation and metabolic dysregulation. The current medical practice uses continuous positive airway pressure (CPAP) as the gold standard tool to manage OSA. It has been shown to improve symptoms and cardiac function, reduce cardiovascular risk and normalise biomarkers. Nonetheless, a full understanding of the factors involved in the deleterious effects of OSA and the best methods to eliminate their occurrence are still poorly understood. In this review, we present the factors and evidence linking OSA to increased risk of cardiovascular conditions.

Inflammasome activation mediated by oxidised low-density lipoprotein in patients with sleep apnoea and early subclinical atherosclerosis

BACKGROUND

Atherosclerosis is a common comorbidity of obstructive sleep apnoea (OSA) patients, caused by the interaction of dyslipidaemia and systemic inflammation. The OSA pro-inflammatory response is mediated by NLRP3 inflammasome activation, which requires a priming signal mediated by intermittent hypoxia (IH) and an activation signal provided by soluble stimulus present in plasma. Our objectives were to study oxidised low-density lipoprotein (oxLDL) expression in OSA patients with or without early subclinical atherosclerosis (eSA) as well as its contribution to NLRP3 activation and tissue factor (TF) release.

METHODS

We analysed oxLDL, key components of the NLRP3 inflammasome cascade and TF in plasma and monocytes from OSA patients and non-apnoeic subjects, with or without eSA as determined by increased carotid intima-media thickness without the appearance of atherosclerotic plaques. The oxLDL contribution to NLRP3 inflammasome activation was assessed using in vitro models.

RESULTS

High levels of oxLDL were identified in plasma from OSA patients, particularly in those with eSA, as well as an overexpression of NLRP3 cascade components and TF. Furthermore, in vitro models showed that both oxLDL and plasma from OSA patients with eSA act synergistically with IH as a priming and activation signal of NLRP3 that enhances the inflammatory response, pyroptosis and TF release.

CONCLUSIONS

OSA patients with eSA exhibit NLRP3 activation by IH and the presence of oxLDL capable of releasing TF, constituting a pathway for the interaction between dyslipidaemia and systemic inflammation in the development of atherosclerotic lesions.

High-density lipoprotein cholesterol efflux capacity in patients with obstructive sleep apnea and its relation with disease severity

Background

Obstructive sleep apnea (OSA) is linked to an accelerated risk of cardiovascular disease (CVD). Some key CVD risk factors are present in patients suffering from OSA such as hypertension, inflammation, oxidative stress, and dyslipidemia. High-density lipoprotein (HDL) cholesterol efflux capacity (CEC) is proposed as a reliable biomarker of HDL function and the present study aimed to quantify this biomarker in patients with OSA.

Methods

ATP binding cassette subfamily A member 1 (ABCA1), non-ABCA1, and total CEC were determined in 69 polysomnographic-confirmed OSA patients and 23 controls. Moreover, paraoxonase (PON) activities, high-sensitivity C-reactive protein (hsCRP), apolipoprotein B (apo B), and apolipoprotein A-I (apo A-I) circulating levels were quantified in the studied population.

Results: All CEC measures were reduced in the OSA group compared to the control group. Strikingly, ABCA1 CEC was diminished in severe OSA in comparison with mild OSA. Furthermore, PON activities and apo A-I showed lower levels, while hsCRP and apo B were elevated in OSA patients compared to controls. Moreover, ABCA1 CEC showed an inverse association with hsCRP and a positive association with apo A-I, while non-ABCA1 CEC presented an association with HDL-C.

Conclusion

These results suggest the presence of an impaired HDL function in OSA. In particular, ABCA1 CEC was associated with disease severity and inflammation which could be a factor increasing the risk of CVD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-022-01723-w.

Relationship between lipids and sleep apnea: Mendelian randomization analysis

BACKGROUND

Lipids increase the risk of sleep apnea; however, the causality between them is still inconclusive.

AIM

To explore the causal relationship between serum lipids and sleep apnea using two-sample Mendelian randomization (MR) analysis.

METHODS

Single nucleotide polymorphism (SNP) data related to serum lipids were obtained from the Global Lipids Genetics Consortium study, which included 188578 individuals of European ancestry. Additionally, sleep apnea-related SNP data were collected from the United Kingdom Biobank study, which comprised 463005 individuals of European ancestry. Two-sample MR analysis was performed to assess the causality between serum lipids and sleep apnea based on the above public data.

RESULTS

Genetically predicted low-density lipoprotein (odds ratio [OR] = 0.99, 95% confidence interval [CI] = 0.99 to 1.00; P = 0.58), high-density lipoprotein (OR = 0.99, 95%CI = 0.99 to 1.00; P = 0.91), triglyceride (OR = 1.00, 95%CI = 0.99 to 1.00; P = 0.92), and total cholesterol (OR = 0.99, 95%CI = 0.99 to 1.00; P = 0.33) were causally unrelated to sleep apnea.

CONCLUSION

Our MR analysis suggests that genetically predicted serum lipids are not risk factors of sleep apnea.

Obstructive Sleep Apnoea and Lipid Metabolism: The Summary of Evidence and Future Perspectives in the Pathophysiology of OSA-Associated Dyslipidaemia

Obstructive sleep apnoea (OSA) is associated with cardiovascular and metabolic comorbidities, including hypertension, dyslipidaemia, insulin resistance and atherosclerosis. Strong evidence suggests that OSA is associated with an altered lipid profile including elevated levels of triglyceride-rich lipoproteins and decreased levels of high-density lipoprotein (HDL). Intermittent hypoxia; sleep fragmentation; and consequential surges in the sympathetic activity, enhanced oxidative stress and systemic inflammation are the postulated mechanisms leading to metabolic alterations in OSA. Although the exact mechanisms of OSA-associated dyslipidaemia have not been fully elucidated, three main points have been found to be impaired: activated lipolysis in the adipose tissue, decreased lipid clearance from the circulation and accelerated de novo lipid synthesis. This is further complicated by the oxidisation of atherogenic lipoproteins, adipose tissue dysfunction, hormonal changes, and the reduced function of HDL particles in OSA. In this comprehensive review, we summarise and critically evaluate the current evidence about the possible mechanisms involved in OSA-associated dyslipidaemia.

Correlation of Medical Comorbidities and Upper Airway Measurements among Dental Patients at Risk of Developing Obstructive Sleep Apnea

Obstructive Sleep Apnea (OSA) is a partial or total upper airway collapse resulting in sleep-breathing disturbances. There are many medical comorbidities associated with OSA; hence, this study is important as the prevalence of patients with medical comorbidities associated with OSA is increasing. The study aimed to correlate medical comorbidities and OSA symptoms of the patients along with their upper airway dimensions using Cone Beam Computed Tomography (CBCT) scans to identify patients at risk of developing OSA. This cross-sectional study included patients who had CBCT imaging taken between 2014 and 2020. A questionnaire was used to gather information on patients’ medical history and OSA symptoms. The upper airway dimensions of the CBCT scans were evaluated before logistic regression and Fisher’s exact test were carried out to determine the relationships between the variables. p ≤ 0.05 was considered statistically significant. Logistic regression revealed an association of longer length (p = 0.016), smaller total volume (p = 0.017) and width (p = 0.010) of upper airways with hypertension. Furthermore, loud snoring was seen in patients with hypertension, heart disease and obesity whereas difficulty concentrating during the day was present in subjects with deviated nasal septum, tonsillitis and depression. For upper airway dimensions, a smaller average volume was associated with loud snoring (p = 0.037), difficulty concentrating during the day (p = 0.002) and mood changes (p = 0.036). A larger anterior-posterior dimension was also associated with excessive daytime sleepiness (p = 0.042), difficulty concentrating during the day (p < 0.001) and mood changes (p = 0.009). Longer airway length was additionally found to be associated with loud snoring (p = 0.021). CBCT taken for dental investigations could be correlated with patients’ medical history and OSA symptoms to screen patients at risk of OSA.

Ameliorating Effect of Morin Hydrate on Chronic Restraint Stress-induced Biochemical Disruption, Neuronal, and Behavioral Dysfunctions in BALB/c Mice

INTRODUCTION

Morin hydrate (MH) is a bioflavonoid component of many fruits and vegetables. Our previous research demonstrated that MH provides neuroprotection in mouse models of acute restraint stress and sleep deprivation by attenuating hippocampal neuronal damage and enhancing memory. Based on these findings, our study investigated the role of MH in chronic stress-induced neuronal and biochemical perturbations in BALB/c mice.

METHODS

Male BALB/c mice were divided into 6 groups (n=6). Groups 1 and 2 received vehicle (10 mL/kg normal saline), groups 3-5 received MH (5, 10, 20 mg/kg IP), while group 6 received ginseng (25 mg/kg) daily and 30 minutes afterward were restrained in a plastic cylindrical restrainer for 14 days.

RESULTS

Immobility time in the forced swim test increased in the MH-treated group, indicating an antidepressant-like effect. Also, a reduction in frequency and duration of open arms exploration was observed in the elevated plus-maze (EPM) test in stressed mice, and administration of MH (5, 10, 20 mg/kg, IP) reversed these effects. An increase in blood levels of glucose, triglycerides, total cholesterol, and brain malondialdehyde and nitrite levels was observed in the stressed groups, which was reversed by MH. Furthermore, MH reversed the stress-induced reduction in HDL cholesterol and glutathione (GSH) levels and attenuated stress-induced alterations in the prefrontal cortex and hippocampus.

CONCLUSION

Our findings suggest that MH attenuated chronic restraint stress-behavioral and biochemical perturbations, probably due to its capability to decrease oxidative stress and brain neuronal damage.

HIGHLIGHTS

Chronic stress perturbs physiological and psychological homeostasis;Morin hydrate normalized chronic stress-induced biochemical disruptions;Morin hydrate attenuated structural changes in prefrontal cortex and hippocampus.

PLAIN LANGUAGE SUMMARY

Stress is a state of being overwhelmed by demands exceeding the personal and social means of coping. Exposure to excessive stress has resulted in disruption of neurochemical and physiological processes, which sometimes manifest as behavioural abnormalities. Therefore to cope with the stressful life style, there is need to develop a therapeutic agent of plant origin. Morin hydrate is a flavonoid with known antioxidant and neuroprotective properties; however, its effect in a stressful condition has not been studies. The study thus evaluated ameliorating effect of Morin hydrate on chronic restraint stress-induced biochemical disruption, neuronal and behavioral dysfunctions in BALB/c mice. To achieve this, mice were exposed to chronic restraint stress protocol for fourteen days. Behavioural changes were examined using various techniques. The vital parameters like antioxidant, glucose and nitrite levels were also taken. Our findings show that Morin hydrate prevented behavioral abnormalities and damage to the brain cells. It also inhibited stress-induced biochemical disturbance.

The impact of sleep apnea syndrome on the altered lipid metabolism and the redox balance

Background

Obstructive sleep apnea (OSA) is a disorder with a significant risk for cardiovascular diseases. Dyslipidemia and redox imbalance belong to potential mechanisms linking OSA with the development of vascular diseases. The main aim of this study was the evaluation of the presence of lipid abnormalities in OSA patients, focusing on small dense low-density lipoprotein (LDL) and high-density lipoprotein (HDL) subfractions and determination of the redox imbalance by evaluating the marker of oxidative damage to plasma lipids - lipoperoxides.

Methods

The study included 15 male subjects with polysomnographically confirmed OSA and 16 male healthy controls. Plasma levels of total cholesterol, LDL and HDL and their subfractions, triacylglycerols and lipoperoxides were determined in all study individuals. Plasma LDL and HDL subfractions were separated by the Lipoprint system which is a polyacrylamide gel electrophoresis. Lipoperoxide levels were determined spectrophotometrically.

Results

OSA patients had significantly higher triacylglycerols, total cholesterol and LDL-cholesterol compared to healthy controls. HDL cholesterol was not significantly different. Of the LDL and HDL subfractions, OSA patients had significantly lower levels of atheroprotective LDL1 and large HDL subfractions and significantly higher levels of atherogenic small dense LDL3–7 and HDL8–10 subfractions. Lipoperoxide levels in patients with OSA were significantly elevated compared to healthy individuals.

Conclusion

The lipoprotein pro-atherogenic phenotype was found in individuals with OSA characterized by increased levels of atherogenic lipoprotein subfractions and reduced levels of atheroprotective subfractions. In addition, a plasma redox imbalance was found in patients with OSA compared to controls by detecting higher oxidative damage to lipids. Abnormalities in lipoprotein levels in patients with OSA, as well as the redox imbalance, could lead to an acceleration of the atherosclerotic process in predisposed individuals and thus represent a significant risk factor for vasular diseases.

Obstructive sleep apnea and cardiovascular comorbidity: common pathophysiological mechanisms to cardiovascular disease

Obstructive sleep apnea (OSA) is associated with many cardiovascular and metabolic diseases. Sleep apnea causes intermittent hypoxemia, chest pressure fluctuations and a reaction from the cerebral cortex in the form of a short awakening during sleep (EEG-activation). The consequences of pathological pathways are studied in experimental models involving cell cultures, animals, and healthy volunteers. At present, the negative impact of intermittent hypoxemia on a variety of pathophysiological disorders of the heart and blood vessels (vascular tone fluctuations, thickening of the intimamedia complex in the vascular wall, direct damaging effect on the myocardium) has a great evidence base. Two other pathological components of OSA (pressure fluctuations and EEG-activation) can also affect cardiovascular system, mainly affecting the increase in blood pressure and changing cardiac hemodynamics. Although these reactions are considered separately in the review, with the development of sleep apnea they occur sequentially and are closely interrelated. As a result, these pathological pathways trigger further pathophysiological mechanisms acting on the heart and blood vessels. It is known that these include excessive sympathetic activation, inflammation, oxidative stress and metabolic dysregulation. In many respects being links of one process, these mechanisms can trigger damage to the vascular wall, contributing to the formation of atherosclerotic lesions. The accumulated data with varying degrees of reliability confirm the participation of OSA through these processes in the formation of cardiovascular disorders. There are factors limiting direct evidence of this interaction (sleep deprivation, causing similar changes, as well as the inability to share the contribution of other risk factors for cardiovascular diseases, in particular arterial hypertension, obesity, which are often associated with OSA). It is necessary to continue the study of processes that implement the pathological effect of OSA on the cardiovascular system.

Body Mass Index Reduction and Selected Cardiometabolic Risk Factors in Obstructive Sleep Apnea: Meta-Analysis

Although clinical studies have been carried out on the effects of weight reduction in sleep apnea patients, no direct link has been shown between weight reduction and changes in cardio-metabolic risk factors. We aimed to analyze changes in the apnea–hypopnea index and selected cardio-metabolic parameters (total cholesterol, triglycerides, glucose, insulin, blood pressure) in relation to the reduction in body mass index in obstructive sleep apnea patients. Medline, Web of Science and Cochrane databases were searched to combine results from individual studies in a single meta-analysis. We identified 333 relevant articles, from which 30 papers were assigned for full-text review, and finally 10 (seven randomized controlled trials and three nonrandomized studies) were included for data analysis. One unit of body mass index reduction was found to significantly influence changes in the apnea–hypopnea index (−2.83/h; 95% CI: −4.24, −1.41), total cholesterol (−0.12 mmol/L; 95% CI: −0.22, −0.01), triglycerides (−0.24 mmol/L; 95% CI: −0.46, −0.02), fasting insulin (−7.3 pmol/L; 95% CI: −11.5, −3.1), systolic (−1.86 mmHg; 95% CI: −3.57, −0.15) and diastolic blood pressure (−2.07 mmHg; 95% CI: −3.79, −0.35). Practical application of lifestyle modification resulting in the reduction of one unit of body mass index gives meaningful changes in selected cardio-metabolic risk factors in obstructive sleep apnea patients.

Obstructive sleep apnea is associated with lower adiponectin and higher cholesterol levels independently of traditional factors and other sleep disorders in middle-aged adults: the ELSA-Brasil cohort

PURPOSE

Obstructive sleep apnea (OSA) may contribute to metabolic and inflammatory deregulation but previous studies failed to consider sleep duration, sleep fragmentation, insomnia, and daytime sleepiness as potential confounders.

METHODS

Consecutive non-diabetic middle-aged participants from the ELSA-Brasil cohort were invited to perform a clinical evaluation, home sleep study for 1 night, and wrist actigraphy for 7 days. OSA was defined by an apnea-hypopnea index ≥ 15 events/h. Participants were stratified according to the presence of OSA measuring the following markers: fasting glucose, glucose tolerance test, homeostatic model assessment of insulin resistance (HOMA-IR) index, fasting insulin, insulin after 2 h of glucose load, glycated hemoglobin, total cholesterol and their fractions, triglycerides, C-reactive protein, TNF-alpha, interleukin-6, interleukin-10, leptin, adiponectin, E-selectin, ADMA, MCP-1, TGF, apolipoprotein B, fibrinogen, and lipoprotein(a). Differences between groups were identified by chi-square test and ANOVA.

RESULTS

We studied 708 participants (mean age: 46 ± 5 years, men: 44%, BMI 26.1 ± 4.1 kg/m²). Compared to no OSA, participants with OSA presented higher levels while fasting and after 2 h glucose load of insulin, HOMA-IR, cholesterol, triglycerides, and C-reactive protein (all p < 0.001). After linear regression analysis adjusting for traditional risk factors plus sleep duration, fragmentation, insomnia, and daytime sleepiness, OSA was negatively associated with adiponectin (β = - 0.271 CI 95% - 0.456 - 0.085) and positively associated with cholesterol (β = 9.707 CI 95% 2.737 16.678). Sex-stratification revealed that these associations were significant for men but not women.

CONCLUSIONS

In non-diabetic middle-age adults, men with OSA presented with lower adiponectin and higher cholesterol levels independently of sleep duration, sleep fragmentation, insomnia, and daytime sleepiness.

Biomarkers and Dynamic Cerebral Autoregulation of Obstructive Sleep Apnea-Hypopnea Syndrome

OBJECTIVE

Patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) have impaired dynamic cerebral autoregulation (dCA). This study aimed to explore whether serum levels of apolipoprotein B-100 (ApoB-100), fibronectin (FN), and ceruloplasmin (CP) were related to impaired dCA in OSAHS.

METHODS

A total of 90 patients with OSAHS from our database management system were enrolled and further divided into three subgroups according to the apnea-hypopnea index (AHI) using polysomnography results: mild (5 ≤ AHI ≤ 15), moderate (15 < AHI ≤ 30), and severe OSAHS (AHI > 30), with 30 patients in each group. Thirty sex- and age-matched healthy controls were recruited for this study. The serum levels of ApoB-100, FN, and CP were measured by enzyme-linked immunosorbent assays. dCA was assessed by analyzing the phase difference (PD) using transfer function analysis.

RESULTS

Serum levels of ApoB-100, FN, and CP were significantly higher in the mild, moderate, and severe OSAHS groups than that in the control group (P<0.001, respectively). The average PD of the moderate and severe OSAHS groups was lower than that of the control group (P=0.001 and P<0.001, respectively). Receiver operating curve analysis revealed that ApoB-100, FN, and CP might be able to distinguish patients with OSAHS from healthy individuals (area under the curve = 0.959 [95% CI 0.92-1.00], 0.987 [95% CI 0.96-1.01], 0.982 [95% CI 0.96-1.00]), respectively, P<0.001). The average PD was linearly correlated with the serum levels of ApoB-100, FN, and CP in patients with OSAHS. Multivariable analysis showed that FN and arousal index in polysomnography were associated with impaired average PD (P<0.001 and P=0.025, respectively).

CONCLUSION

Serum levels of ApoB-100, FN, and CP increased in patients with OSAHS. dCA was compromised in patients with OSAHS and was positively correlated with ApoB-100, FN, and CP serum levels, and FN serum levels and arousal index in polysomnography were independently associated with impaired dCA.

Deep phenotyping of myalgic encephalomyelitis/chronic fatigue syndrome in Japanese population

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex and debilitating disease with no molecular diagnostics and no treatment options. To identify potential markers of this illness, we profiled 48 patients and 52 controls for standard laboratory tests, plasma metabolomics, blood immuno-phenotyping and transcriptomics, and fecal microbiome analysis. Here, we identified a set of 26 potential molecular markers that distinguished ME/CFS patients from healthy controls. Monocyte number, microbiome abundance, and lipoprotein profiles appeared to be the most informative markers. When we correlated these molecular changes to sleep and cognitive measurements of fatigue, we found that lipoprotein and microbiome profiles most closely correlated with sleep disruption while a different set of markers correlated with a cognitive parameter. Sleep, lipoprotein, and microbiome changes occur early during the course of illness suggesting that these markers can be examined in a larger cohort for potential biomarker application. Our study points to a cluster of sleep-related molecular changes as a prominent feature of ME/CFS in our Japanese cohort.

Circulating levels of oxidized low-density lipoprotein in patients with obstructive sleep apnea: a systematic review and meta-analysis

BACKGROUND

Obstructive sleep apnea (OSA) is associated with an increased risk of developing atherosclerotic cardiovascular disease (ASCVD). Patients with OSA have increased levels of oxidative stress and several studies have shown higher levels of oxidative stress markers. Oxidized-LDL (Ox-LDL) is an important risk factor for ASCVD and a number of studies have measured its levels in patients with OSA, though results from these studies are conflicting. This meta-analysis aimed to reassess circulating levels of Ox-LDL in patients with OSA in comparison with controls.

METHODS

Studies evaluating Ox-LDL levels in patients with OSA and controls were explored in databases of PubMed, EMBASE, Scopus, and Web of Science. Two authors independently performed the search from January 1990 to February 2019. Two authors independently screened the studies according to title, abstract, and full text. In addition, the Newcastle-Ottawa Quality Assessment Scale was utilized to evaluate the quality of the studies. The impact of OSA on Ox-LDL levels was determined using the random effects model.

RESULTS

Of 195 articles retrieved, 98 were duplicates, 49 were excluded by title, 20 excluded by abstract, and 22 by full texts. Six eligible studies were included in the meta-analysis. Pooled analysis demonstrated that Ox-LDL increased in patients with OSA compared with controls. In addition, subgroup analysis revealed that studies matching age or BMI between OSA patients and controls showed no significant difference between patients with OSA and healthy controls, while unmatched studies had higher levels of Ox-LDL in patients with OSA in comparison with controls.

CONCLUSION

This study demonstrated higher circulating concentrations of Ox-LDL in patients with OSA. However, no significant difference was found in studies in which patients and controls were matched for age and BMI, suggesting the involvement of these two confounding factors as a cause for elevated concentrations of circulating Ox-LDL in patients with OSA.

Sleep-disordered breathing in adolescents with obesity: When does it start to affect cardiometabolic health?

BACKGROUND AND AIMS

Pediatric obesity and sleep-disordered breathing (SDB) are associated with cardiometabolic risk (CMR), but the degree of severity at which SDB affects cardiometabolic health is unknown. We assessed the relationship between the CMR and the apnea-hypopnea index (AHI), to identify a threshold of AHI from which an increase in the CMR is observed, in adolescents with obesity. We also compared the clinical, cardiometabolic and sleep characteristics between adolescents presenting a high (CMR+) and low CMR (CMR-), according to the threshold of AHI.

METHODS AND RESULTS

114 adolescents with obesity were recruited from three institutions specialized in obesity management. Sleep and SDB as assessed by polysomnography, anthropometric parameters, fat mass (FM), glucose and lipid profiles, and blood pressure (BP) were measured at admission. Continuous (MetScore_FM) and dichotomous (metabolic syndrome, MetS) CMR were determined. Associations between MetScore_FM and AHI adjusted for BMI, sex and age were assessed by multivariable analyses. Data of 82 adolescents were analyzed. Multivariable analyses enabled us to identify a threshold of AHI = 2 above which we observed a strong and significant association between CMR and AHI (Cohen's d effect-size = 0.57 [0.11; 1.02] p = 0.02). Adolescents with CMR+ exhibited higher MetScore_FM (p < 0.05), insulin resistance (p < 0.05), systolic BP (p < 0.001), sleep fragmentation (p < 0.01) and intermittent hypoxia than CMR- group (p < 0.0001). MetS was found in 90.9% of adolescents with CMR+, versus 69.4% in the CMR- group (p < 0.05).

CONCLUSIONS

The identification of a threshold of AHI ≥ 2 corresponding to the cardiometabolic alterations highlights the need for the early management of SDB and obesity in adolescents, to prevent cardiometabolic diseases.

CLINICAL TRIALS

NCT03466359, NCT02588469 and NCT01358773.

Obstructive sleep apnea and dyslipidemia: from animal models to clinical evidence

Lipid metabolism deregulation constitutes the pathogenic basis for the development of atherosclerosis and justifies a high incidence of cardiovascular-related morbidity and mortality. Some data suggest that dyslipidemia may be associated with sleep-disordered breathing, mainly obstructive sleep apnea (OSA), due to alterations in fundamental biochemical processes, such as intermittent hypoxia (IH). The aim of this systematic review was to identify and critically evaluate the current evidence supporting the existence of a possible relationship between OSA and alterations in lipid metabolism. Much evidence shows that, during the fasting state, OSA and IH increase lipid delivery from the adipose tissue to the liver through an up-regulation of the sterol regulatory element-binding protein-1 and stearoyl-CoA desaturase-1, increasing the synthesis of cholesterol esters and triglycerides. In the postprandial state, lipoprotein clearance is delayed due to lower lipoprotein lipase activity, probably secondary to IH-up-regulation of angiopoietin-like protein 4 and decreased activity of the peroxisome proliferator-activated receptor alpha. Moreover, oxidative stress can generate dysfunctional oxidized lipids and reduce the capacity of high-density lipoproteins (HDL) to prevent low-density lipoprotein (LDL) oxidation. In the clinical field, several observational studies and a meta-regression analysis support the existence of a link between OSA and dyslipidemia. Although there is evidence of improved lipid profile after apnea-hypopnea suppression with continuous positive airway pressure (CPAP), the majority of the data come from observational studies. In contrast, randomized controlled trials evaluating the effects of CPAP on lipid metabolism present inconclusive results and two meta-analyses provide contradictory evidence.

Sleep, Autonomic Nervous Function and Atherosclerosis

Behavioral and psychosocial factors related to development of cardiovascular disease have been gaining increased attention. Notably, sleep is considered to be one of the most important behavioral factors involved in progression of atherosclerosis and cardiovascular events, with autonomic nervous function a potential mechanism. Several studies have shown associations of sleep and autonomic dysfunction with major surrogate markers of atherosclerosis, such as carotid intima-media thickness and arterial stiffness. Endocrinological, immunological, oxidative, inflammatory, and metabolic responses, as well as endothelial dysfunction may mediate the effects of the autonomic nervous system. For this review, we examined recent findings related to sleep, autonomic nervous dysfunction, and atherosclerosis, with the aim of understanding the involved pathophysiological mechanisms.

Association Between Serum Lipid Profile and Obstructive Respiratory Events During REM and Non-REM Sleep

Purpose

Obstructive sleep apnoea (OSA) represents a risk for dyslipidaemia. Obstructive respiratory events during rapid eye movement (REM) sleep are more strongly related to the development of hypertension and diabetes than in non-REM. However, the relationship between sleep phases and serum lipid profile is unclear. We aimed to analyse the relationship between obstructive respiratory events in REM and non-REM sleep as well as serum lipid profile.

Methods

Polysomnography was performed in 94 adult subjects who did not take any lipid-modifying medications. Fasting venous blood sample was taken the following morning for total cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol, lipoprotein(a), apoprotein A1 (ApoA1) and for apoprotein B (ApoB) measurements. Lipid profiles were correlated with apnoea–hypopnoea index (AHI) during REM (AHI_REM) and non-REM (AHI_NREM) stages in all subjects. In addition, lipid profiles were compared between REM-dependent OSA patients (AHI_REM ≥ 5/h, but AHI_NREM < 5/h) and control subjects (both AHI_REM and AHI_NREM < 5/h).

Results

AHI_REM correlated only with triglyceride concentrations (p = 0.04, Spearman’s rho, ρ = 0.21). In contrast, there was a significant association between AHI_NREM and triglyceride (p = 0.02, ρ = 0.23), ApoB (p = 0.03, ρ = 0.21), HDL-C (p < 0.01, ρ = − 0.32) as well as ApoA1 levels (p = 0.04, ρ = − 0.21). However, these correlations were not present after adjustment for BMI (all p > 0.05). There was no difference in the lipid profile of REM-dependent OSA subjects and healthy controls (p > 0.05).

Conclusions

Altered serum lipid profile is equally associated with a disturbed REM and non-REM sleep in OSA. Obesity must be considered as a strong covariate when interpreting lipid data in sleep apnoea.

Betatrophin association with serum triglyceride levels in obstructive sleep apnea patients

BACKGROUND

Obstructive sleep apnea (OSA) is a common sleep problem, in which patients are at increased risk for metabolic and cardiovascular problems, including metabolic syndrome, diabetes mellitus (DM), and dyslipidemia. Betatrophin is a novel protein that regulates fatty acid and triglyceride (TG) metabolism and is related to obesity and metabolic abnormalities, including metabolic syndrome, DM, and dyslipidemia. Although OSA and betatrophin share common abnormalities, their relationship has not been investigated.

AIM

The aim of this study is to investigate the relationships among betatrophin, OSA, and the serum lipid profile.

METHODS

Ninety consecutive patients with suspected OSA underwent polysomnography (PSG) to confirm OSA. Plasma betatrophin, leptin, adiponectin, and the full lipid profile were analyzed. The patients were categorized as OSA or control based on the apnea-hypopnea index (AHI).

RESULTS

About 61% of patients had OSA, and 39% had normal PSG. The levels of betatrophin, leptin, and adiponectin were higher in patients with OSA (256.59 ± 29.35, 374.20 ± 37.93, and 17.86 ± 2.63 μg/mL, respectively) compared to the controls (141.86 ± 26.20, 205.53 ± 14.75, and 7.52 ± 1.02 μg/mL, respectively). Betatrophin levels were correlated with the AHI, leptin (r = 0.413, P = 0.002, r = 0.782, P = 0.000). TG levels were significantly higher, and high-density lipoprotein cholesterol (HDL-C) levels were lower, in OSA patients compared to controls (244 ± 20.33 vs. 138 ± 14.89, and 37.21 ± 1.26 vs. 43.78 ± 1.62, respectively). The TG level was correlated with betatrophin (r = 0.353, P = 0.013). Multiple regression analysis showed that the AHI, leptin, and arousals were independent predictors of betatrophin level (B = 1.70 P = 0.046 95%, B = 0.56 P < 0.005, and B = 1, 2, P = 0.003, respectively).

CONCLUSIONS

Our results suggest a complex relationship between OSA, betatrophin, TG, and HDL, as well as other adipokines. Our results require further investigation to assess this complex association and re-evaluate previous related studies.

Catestatin serum levels are increased in male patients with obstructive sleep apnea

PURPOSE

Obstructive sleep apnea (OSA) is a complex sleep disorder associated with autonomic and sympathetic dysregulation. To the contrary, catestatin, an endogenous pleiotropic peptide cleaved from chromogranin A, is known for its inhibitory effects on catecholamine release and sympathetic activity. The aims of the study were to determine catestatin serum levels among male OSA patients compared to healthy control subjects and to explore associations of catestatin with anthropometric, polysomnographic, and lipid profile parameters.

METHODS

Seventy-eight male OSA patients aged 50.3 ± 8.8 years and 51 age/sex/BMI-matched control subjects aged 50.4 ± 7.8 years were enrolled in the study. Catestatin serum levels were determined by an enzyme-linked immunosorbent assay (ELISA).

RESULTS

Catestatin serum levels were significantly higher among OSA patients compared to control subjects (2.9 ± 1.2 vs. 1.5 ± 1.1 ng/mL, p < 0.001). Serum catestatin levels significantly correlated with apnea-hypopnea index (AHI) among non-obese OSA subjects (r = 0.466, p = 0.016; β = 0.448, p = 0.026), while in whole OSA population, catestatin levels significantly correlated with neck circumference (r = 0.318, p < 0.001; β = 0.384, p < 0.001) and high-density lipoprotein (HDL) cholesterol (r = - 0.320, p < 0.001; β = - 0.344, p < 0.001). In multivariate-adjusted regression model, serum catestatin was significant and independent predictor of OSA status (OR 4.98, 95% CI 2.17-11.47, p < 0.001).

CONCLUSIONS

Catestatin serum levels are significantly increased in male OSA population and positively correlate with disease severity in non-obese patients. OSA status is independently predicted by catestatin levels; however, this finding is restricted to patients with moderate-to-severe disease. Further studies are necessary to elucidate the mechanistic role of catestatin in the complex pathophysiology of OSA.

Treating Obstructive Sleep Apnea and Chronic Intermittent Hypoxia Improves the Severity of Nonalcoholic Fatty Liver Disease in Children

OBJECTIVE

To determine the effects of treating obstructive sleep apnea/nocturnal hypoxia on pediatric nonalcoholic fatty liver disease (NAFLD) severity and oxidative stress.

STUDY DESIGN

Biopsy proven participants (n = 9) with NAFLD and obstructive sleep apnea/hypoxia were studied before and after treatment with continuous positive airway pressure (CPAP) for sleep disordered breathing, including laboratory testing and markers of oxidative stress, urine F(2)-isoprostanes.

RESULTS

Adolescents (age 11.5 ± 1.2 years; body mass index, 29.5 ± 3.8 kg/m²) with significant NAFLD (mean histologic necroinflammation grade, 2.3 ± 0.9; fibrosis stage, 1.4 ± 1.3; NAFLD Activity Score summary, 4.8 ± 1.6) had obstructive sleep apnea/hypoxia by polysomnography. At baseline, they had severe obstructive sleep apnea/hypoxia, elevated aminotransferases, the metabolic syndrome, and significant oxidative stress (high F(2)-isoprostanes). Obstructive sleep apnea/hypoxia was treated with home CPAP for a mean 89 ± 62 days. Although body mass index increased, obstructive sleep apnea/hypoxia severity improved on CPAP and was accompanied by reduced alanine aminotransferase, metabolic syndrome markers, and F(2)-isoprostanes.

CONCLUSIONS

This study provides strong evidence that treatment of obstructive sleep apnea/nocturnal hypoxia with CPAP in children with NAFLD may reverse parameters of liver injury and reduce oxidative stress. These data also suggest CPAP as a new therapy to prevent progression of NAFLD in those children with obesity found to have obstructive sleep apnea/nocturnal hypoxia.

Association between obstructive sleep apnea and non-alcoholic fatty liver disease: a systematic review and meta-analysis

The relationship between obstructive sleep apnea (OSA) and non-alcoholic fatty liver disease (NAFLD) has been an issue of great concern. The primary purpose of this study was to determine the influence of OSA on the levels of liver enzymes including alanine transaminase (ALT) and aspartate transaminase (AST). The secondary purpose was to estimate the effect of OSA on the histological lesions of NAFLD, such as steatosis, lobular inflammation, ballooning degeneration, fibrosis, as well as NAFLD activity score (NAS). A systematic literature review using PubMed, Cochrane Library, Embase, and Ovid technologies from January 2007 to April 2017 was performed, and 9 studies (2272 participants) that met the selection criteria were evaluated. The present study demonstrated that OSA was related to ALT levels, but no significant correlation was found with AST levels. The subgroup analysis showed that the severity of OSA was associated with ALT levels, not with AST levels. The meta-regression analysis showed that age, sex, homeostasis model assessment, diabetes mellitus, body mass index, and waist circumference did not have a significant effect on the levels of ALT and AST. OSA was also found to be significantly correlated with steatosis, lobular inflammation, ballooning degeneration, and fibrosis, but was not correlated with NAS. OSA was independently related to the development and progression of NAFLD in terms of liver enzyme level and histological alterations. Future studies should investigate the possible relevant mechanisms, thereby guiding the exploration of potential therapeutic implications to prevent the progression of disease.

Interactions between and Shared Molecular Mechanisms of Diabetic Peripheral Neuropathy and Obstructive Sleep Apnea in Type 2 Diabetes Patients

Type 2 diabetes (T2D) accounts for about 90% of all diabetes patients and incurs a heavy global public health burden. Up to 50% of T2D patients will eventually develop neuropathy as T2D progresses. Diabetic peripheral neuropathy (DPN) is a common diabetic complication and one of the main causes of increased morbidity and mortality of T2D patients. Obstructive sleep apnea (OSA) affects over 15% of the general population and is associated with a higher prevalence of T2D. Growing evidence also indicates that OSA is highly prevalent in T2D patients probably due to diabetic peripheral neuropathy. However, the interrelations among diabetic peripheral neuropathy, OSA, and T2D hitherto have not been clearly elucidated. Numerous molecular mechanisms have been documented that underlie diabetic peripheral neuropathy and OSA, including oxidative stress, inflammation, endothelin-1, vascular endothelial growth factor (VEGF), accumulation of advanced glycation end products, protein kinase C (PKC) signaling, poly ADP ribose polymerase (PARP), nitrosative stress, plasminogen activator inhibitor-1, and vitamin D deficiency. In this review, we seek to illuminate the relationships among T2D, diabetic peripheral neuropathy, and OSA and how they interact with one another. In addition, we summarize and explain the shared molecular mechanisms involved in diabetic peripheral neuropathy and OSA for further mechanistic investigations and novel therapeutic strategies for attenuating and preventing the development and progression of diabetic peripheral neuropathy and OSA in T2D.

Determinants of obstructive sleep apnea syndrome: Pro-inflammatory state and dysfunction of high-density lipoprotein

OBJECTIVE

The goal of this study was to determine variables preceding and predicting incident obstructive sleep apnea syndrome (OSAS) in the population at large.

METHODS

Anthropometric, lipid, and non-lipid variables in participants with newly developing OSAS (n = 131) were compared with those of a cohort sample (n = 2615) of the Turkish Adult Risk Factor study. Available values preceding (by a median of 32 mo) the development of OSAS were used in multivariable Cox regression models.

RESULTS

Significant determinants of OSAS assessed by group differences were waist/neck circumference and fibrinogen. Fasting triacylglycerols, systolic blood pressure, and C-reactive protein in men and low sex hormone-binding globulin and elevated homeostatic model assessment in women were further significant covariates. Cox regression analysis for the risk of incident OSAS confirmed the independent predictive value of central obesity measures, especially neck circumference (having a twofold hazard ratio) and younger age. Age-adjusted former smoking status and-compared with the lowest tertile-the upper two tertiles of fibrinogen (relative risk = 1.66, 95% confidence interval: 1.05-2.63) were significant predictors. Elevated triacylglycerols in males and high apolipoprotein B and lowest high-density lipoprotein cholesterol tertile in females also predicted subsequent OSAS. Systolic blood pressure and total cholesterol did not prove to be independent predictors in multivariable adjusted Cox models in which partial sex-dependent independence of obesity measures of the previously stated five variables was essentially retained.

CONCLUSIONS

An enhanced pro-inflammatory state appeared to be the underlying pathophysiologic mechanism for OSAS, whereas in men, the added factor of high-density lipoprotein dysfunction was suggested. Because it contributes to the pro-inflammatory state, discontinuance of smoking was another further significant predictor of OSAS.

Isoprostanes, neuroprostanes and phytoprostanes: An overview of 25years of research in chemistry and biology

Since the beginning of the 1990's diverse types of metabolites originating from polyunsaturated fatty acids, formed under autooxidative conditions were discovered. Known as prostaglandin isomers (or isoprostanoids) originating from arachidonic acid, neuroprostanes from docosahexaenoic acid, and phytoprostanes from α-linolenic acid proved to be prevalent in biology. The syntheses of these compounds by organic chemists and the development of sophisticated mass spectrometry methods has boosted our understanding of the isoprostanoid biology. In recent years, it has become accepted that these molecules not only serve as markers of oxidative damage but also exhibit a wide range of bioactivities. In addition, isoprostanoids have emerged as indicators of oxidative stress in humans and their environment. This review explores in detail the isoprostanoid chemistry and biology that has been achieved in the past three decades.

Consequences of Obstructive Sleep Apnea: Cardiovascular Risk of Obstructive Sleep Apnea and Whether Continuous Positive Airway Pressure Reduces that Risk

Obstructive sleep apnea (OSA) is present in up to 25% of otherwise healthy individuals. OSA is associated with intermittent hypoxia, oxidative stress, sympathetic activation, and an inflammatory response. These perturbations mediate the role of OSA as an independent and modifiable risk factor for cardiovascular disease (CVD). OSA can induce CVD or accelerate the progression of CVD into an end-stage disorder, including heart failure and stroke. Current clinical recommendations are based on existing clinical trial data and the clinical experience of our program; current and future clinical trials will help to optimize management of OSA in the setting of CVD.

Obstructive Sleep Apnea and Lipid Abnormalities

BACKGROUND

There has been a great interest in the interaction between obstructive sleep apnea (OSA) and metabolic dysfunction, but there is no consistent data suggesting that OSA is a risk factor for dyslipidemia.

AIM

The aim of this cross-sectional study was to evaluate the prevalence of lipid abnormalities in patients suspected of OSA, referred to our sleep laboratory for polysomnography.

MATERIAL AND METHODS

Two hundred patients referred to our hospital with suspected OSA, and all of them underwent for standard polysomnography. All patients with respiratory disturbance index (RDI) above 15 were diagnosed with OSA. In the morning after 12 hours fasting, the blood sample was collected from all patients. Blood levels of triglycerides, total cholesterol, high-density lipoprotein cholesterol (HDL) and low-density lipoprotein cholesterol (LDL), were determined in all study patients. In the study, both OSA positive and OSA negative patients were divided according to the body mass index (BMI) in two groups. The first group with BMI ≤ 30 kg/m^2 and the second group with BMI > 30 kg/m^2.

RESULTS

OSA positive patients with BMI ≤ 30 kg/m^2 had statistically significant higher levels of triglycerides and total cholesterol, and statistically significant lower level of HDL compared to OSA negative patients with BMI ≤ 30. There were no statistically significant differences in age and LDL levels between these groups. OSA positive patients with BMI > 30 kg/m^2 had higher levels of triglycerides, total cholesterol and LDL and lower levels of HDL versus OSA negative patients with BMI > 30 kg/m^2, but without statistically significant differences.

CONCLUSION

OSA and obesity are potent risk factors for dyslipidemias. OSA could play a significant role in worsening of lipid metabolism in non-obese patients. But in obese patients, the extra weight makes the metabolic changes of lipid metabolism, and the role of OSA is not that very important like in non-obese patients.

Obstructive sleep apnea predicts risk of metabolic syndrome independently of obesity: a meta-analysis

INTRODUCTION

Obstructive sleep apnea (OSA) has been suggested to be associated with a high risk of metabolic syndrome (MS). However, results on whether the association between OSA and risk of MS is independent of obesity, and the effect of nocturnal intermittent hypoxia (IH) on MS, are conflicting. Our purpose was to estimate the magnitude of the independent association between OSA and risk of MS and further explore whether nocturnal IH in OSA plays a role in MS risk.

MATERIAL AND METHODS

The PubMed and EMBASE databases were systematically searched (until January 21, 2015) for available observational evidence. Unadjusted and body mass index (BMI)-adjusted pooled odds ratios (ORs) for MS in OSA or higher nocturnal IH were calculated using fixed or random models. Tests of homogeneity, publication bias, and robustness of the results were performed.

RESULTS

A total of 13 independent studies (involving 857 participants in 3 case-control studies and 7077 participants in 10 cross-sectional studies) were included. The OSA was significantly associated with an increased risk of MS in a meta-analysis of 10 studies (pooled OR = 1.72, 95% CI: 1.31-2.26, p < 0.001), with a BMI-adjusted pooled OR of 1.97 (95% CI: 1.34-2.88, p < 0.001). Pooled results from 3 studies on the oxygen desaturation index (ODI) and MS risk (OR = 1.96, 95% CI: 1.73-2.22, p < 0.001) and 3 studies on the cumulative percentage of sleep time with SpO₂ below 90% (CT90) and MS risk (OR = 1.05, 95% CI: 1.02-1.07, p < 0.001) were also significant.

CONCLUSIONS

Our findings demonstrated a significant association between OSA and increased MS risk independent of BMI, and further indicated a role of nocturnal IH in this association.

Nocturnal hypoxia-induced oxidative stress promotes progression of pediatric non-alcoholic fatty liver disease

BACKGROUND & AIMS

Oxidative stress is proposed as a central mediator in NAFLD pathogenesis, but the specific trigger for reactive oxygen species generation has not been clearly delineated. In addition, emerging evidence shows that obesity related obstructive sleep apnea (OSA) and nocturnal hypoxia are associated with NAFLD progression in adults. The aim of this study was to determine if OSA/nocturnal hypoxia-induced oxidative stress promotes the progression of pediatric NAFLD.

METHODS

Subjects with biopsy proven NAFLD and lean controls were studied. Subjects underwent polysomnograms, liver histology scoring, laboratory testing, urine F(2)-isoprostanes (measure of lipid peroxidation) and 4-hydroxynonenal liver immunohistochemistry (in situ hepatic lipid peroxidation).

RESULTS

We studied 36 adolescents with NAFLD and 14 lean controls. The OSA/hypoxia group (69% of NAFLD subjects) had more severe fibrosis (64% stage 0-2; 36% stage 3) than those without OSA/hypoxia (100% stage 0-2), p=0.03. Higher F(2)-isoprostanes correlated with apnea/hypoxia index (r=0.39, p=0.03), % time SaO2 <90% (r=0.56, p=0.0008) and inversely with SaO2 nadir (r=-0.46, p=0.008). OSA/hypoxia was most severe in subjects with the greatest 4HNE staining (p=0.03). Increasing F(2)-isoprostanes(r=0.32, p=0.04) and 4HNE hepatic staining (r=0.47, p=0.007) were associated with worsening steatosis. Greater oxidative stress occurred in subjects with definite NASH as measured by F(2)-isoprostanes (p=0.06) and hepatic 4HNE (p=0.03) compared to those with borderline/not NASH.

CONCLUSIONS

These data support the role of nocturnal hypoxia as a trigger for localized hepatic oxidative stress, an important factor associated with the progression of NASH and hepatic fibrosis in obese pediatric patients.

LAY SUMMARY

Obstructive sleep apnea and low nighttime oxygen are associated with NAFLD progression in adults. In this study, we show that adolescents with NAFLD who have OSA and low oxygen have significant scar tissue in their livers. NAFLD subjects affected by OSA and low oxygen have a greater imbalance between the production of free radicals and their body's ability to counteract their harmful effects than subjects without OSA and low oxygen. This study shows that low oxygen levels may be an important trigger in the progression of pediatric NASH.

The Association Between Obstructive Sleep Apnea and Carotid Intima-Media Thickness: A Systematic Review and Meta-Analysis

Obstructive sleep apnea (OSA) has been suggested as a risk factor for carotid atherosclerosis. The present meta-analysis aimed to evaluate the association between OSA and carotid intima-media thickness (CIMT). Eighteen studies comparing CIMT of patients with OSA versus non-OSA patients were included. Quantitative data synthesis was used to pool weighted standardized difference in means (SMD) of CIMT in a random-effects model. Compared to healthy controls, patients with OSA had a significantly higher CIMT (SMD: 0.881; 95% confidence interval [CI]: 0.647-1.115; P < .001). Due to the great heterogeneity, a subgroup analysis was conducted based on the study design. The pooled SMD of CIMT between patients with OSA and healthy controls were 0.810 (95% CI: 0.676-0.943; P < .001) and 1.008 (95% CI: 0.506-1.510; P < .001) in matched and unmatched group, respectively. Moreover, the correlation of apnea-hypopnea index and CIMT was moderate ( r = .389; 95% CI: 0.315-0.459; P < .001). After adjustment for several major confounders, OSA is an independent risk factor for CIMT. These findings remind clinicians to screen for cardiovascular diseases in patients with OSA.

Quality of life, depression and dietary intake in Obstructive Sleep Apnea patients

BACKGROUND

The aim of this study was to analyze the association between depression, quality of life and dietary intake in newly diagnosed Obstructive Sleep Apnea (OSA) patients.

METHODS

From 153 eligible patients suffering from sleep disturbances, 64 met inclusion and exclusion criteria. The polysomnography was used for OSA diagnosis. The quality of life (QOL) was assessed by WHOQOL-BREF questionnaire, self-reported chronotype by morningness-eveningness questionnaire and level of depression by Beck's Depression Inventory. Blood pressure and parameters of glucose and lipid metabolism were assessed by routine methods. The dietary intake was evaluated by 24-hr dietary recalls.

RESULTS

Significantly negative associations were found between depression inventory and QOL. Better QOL for physical health and social relationships was observed in the "definitely morning" chronotype. The "morning type" of patients was positively related to the intake of fat, monounsaturated fatty acids and vitamin B12. Correlations between QOL and diastolic blood pressure, HDL-cholesterol, TG, fasting glucose, as well as protein and vitamin B6 intake were found.

CONCLUSIONS

In conclusion, both chornotype and depression influence QOL in OSA patients where morning type is associated with better physical health and social relationships and increase in depression index deteriorate physical health, psychological and social relationship QOL domains. QOL as well as depression and chornotype are also influenced by selected cardio-metabolic factors and dietary intake.

Comorbidities Associated with Obstructive Sleep Apnea: a Retrospective Study

Introduction Obstructive sleep apnea (OSA) is characterized by partial or complete recurrent upper airway obstruction during sleep. OSA brings many adverse consequences, such as hypertension, obesity, diabetes mellitus, cardiac and encephalic alterations, behavioral, among others, resulting in a significant source of public health care by generating a high financial and social impact. The importance of this assessment proves to be useful, because the incidence of patients with comorbidities associated with AOS has been increasing consistently and presents significant influence in natural disease history.

Objective The objective of this study is to assess major comorbidities associated with obstructive sleep apnea (OSA) and prevalence in a group of patients diagnosed clinically and polysomnographically with OSA.

Methods This is a retrospective study of 100 charts from patients previously diagnosed with OSA in our service between October 2010 and January 2013.

Results We evaluated 100 patients with OSA (84 men and 16 women) with a mean age of 50.05 years (range 19–75 years). The prevalence of comorbidities were hypertension (39%), obesity (34%), depression (19%), gastroesophageal reflux disease (GERD) (18%), diabetes mellitus (15%), hypercholesterolemia (10%), asthma (4%), and no comorbidities (33%). Comorbidities occurred in 56.2% patients diagnosed with mild OSA, 67.6% with moderate OSA, and 70% of patients with severe OSA.

Conclusion According to the current literature data and the values obtained in our paper, we can correlate through expressive values obesity with OSA and their apnea hypopnea index (AHI) values. However, despite significant prevalence of OSA with other comorbidities, our study could not render expressive significance values able to justify their correlations.

The Impact of Obstructive Sleep Apnea and Tobacco Smoking on Endothelial Function

BACKGROUND

Endothelial dysfunction has been recognized to occur in the context of obstructive sleep apnea (OSA) or tobacco smoking. However, the deleterious effect on vascular function with concurrence of both conditions is largely unknown.

OBJECTIVE

To investigate whether the concurrence of OSA and smoking poses an additive detriment to endothelial dysfunction.

METHODS

Chinese men without a history of chronic medical illness were invited to complete a questionnaire including smoking pack-year exposure, polysomnography and peripheral arterial tonometry (PAT) for endothelial function. Serum 8-isoprostane, advanced oxidation protein products (AOPP) and monocyte chemo-attractant protein-1 (MCP-1) were measured.

RESULTS

114 men were successfully enrolled. PAT ratio, adjusted for age and body mass index, correlated inversely with overall severity of OSA: apnea-hypopnea index (AHI), r = -0.160 (p = 0.092); oxygen desaturation index, r = -0.214 (p = 0.024); duration of oxygen saturation <90%, r = -0.219 (p = 0.020); and minimum oxygen saturation, r = 0.250 (p = 0.008). The PAT ratio decreased with increasing pack-year group (p = 0.018). It was lower with concurrent smoking history and moderate-severe OSA (AHI ≥15/h) compared to having one or neither factor (p = 0.011). Serum levels of 8-isoprostane and AOPP were positively related to severity of OSA, while MCP-1 correlated with smoking quantity. Multiple linear regression analyses showed that severity of intermittent hypoxia, MCP-1 and pack-year exposure were independent predictors of PAT ratio.

CONCLUSION

While OSA, in particular intermittent hypoxemia, and tobacco smoking were independent risk factors, the concurrence of moderate-severe OSA and smoking was associated with the most severe impairment in endothelial function.

Clinical manifestations of sleep apnea

Obstructive sleep apnea (OSA) may manifest in a number of ways from subtle intrusion into daily life to profound sleepiness, snoring, witnessed apneas and other classic symptoms. Although there is increasing evidence suggesting OSA can adversely affect health in a variety of ways, this disorder remains underdiagnosed. The most well-escribed health consequences of OSA relate to the cardiovascular system. Hypertension and arrhythmias have a strong association with OSA, and evidence suggests that treatment of OSA in patients with refractory hypertension and in patients planning cardioversion for atrial fibrillation may be of particularly importance. Significant associations between heart failure and OSA as well as complex sleep apnea have also been well-described. Cerebrovascular insult, impaired neurocognition, and poorly controlled mood disorder are also associated with in OSA. Therapy for OSA may ameliorate atherosclerotic progression and improve outcomes post-cerebrovascular accident (CVA). OSA should be considered in patients complaining of poor concentration at work, actual or near-miss motor vehicle accidents, and patients with severe sleepiness as a component of their co-morbid mood disorders. The metabolic impact of OSA has also been studied, particularly in relation to glucose homeostasis. Also of interest is the potential impact OSA has on lipid metabolism. The adverse effect untreated OSA has on glucose tolerance and lipid levels has led to the suggestion that OSA is yet another constituent of the metabolic syndrome. Some of these metabolic derangements may be related to the adverse effects untreated OSA has on hepatic health. The cardiovascular, neurocognitive, and metabolic manifestations of OSA can have a significant impact on patient health and quality of life. In many instances, evidence exists that therapy not only improves outcomes in general, but also modifies the severity of co-morbid disease. To mitigate the long-term sequela of this disease, providers should be aware of the subtle manifestations of OSA and order appropriate testing as necessary.

Elevated low-density lipoprotein cholesterol is independently associated with obstructive sleep apnea: evidence from a large-scale cross-sectional study

BACKGROUND

Lipid metabolism disorder is recognized to be associated with obstructive sleep apnea (OSA); however, inconsistent results have been reported. The aim of this study was to evaluate the association between lipid profile and OSA with adjustments for multiple confounding factors.

METHODS

In total, 2983 subjects were recruited from the Shanghai Sleep Health Study (SSHS) during 2007-2013. Data for overnight polysomnography (PSG) parameters, serum lipids, fasting blood glucose, insulin levels, and anthropometric measurements were collected. Multivariable logistic regression analyses were used to determine the correlation between lipid profile and OSA with adjustments for confounders including lipids, age, gender, Epworth sleepiness scale, body mass index, waist/hip ratio, glucose, insulin resistance, hypertension, and smoking.

RESULTS

The prevalence of hyper total cholesterol (TC), hyper triglycerides, hypo high-density lipoprotein cholesterol, hyper low-density lipoprotein cholesterol (LDL-C), hyper apolipoprotein (apo) A-I, and hyper apoB differed significantly between the non-OSA and OSA patients. Without considering the interaction across different lipids, TC, LDL-C, and apoB were independently associated with OSA in primary multivariable logistic regression analyses; the odds ratios (ORs) and 95 % confidence intervals (CIs) were 1.262 (1.109-1.438), 1.432 (1.233-1.664), and 5.582 (2.643-11.787), respectively. However, only LDL-C (OR = 1.430, 95 % CI = 1.221-1.675) was found to be an independent risk factor for OSA in further multivariable logistic regression analyses.

CONCLUSIONS

We demonstrated that patients with OSA had a higher percentage of dyslipidemia than subjects without OSA. Of the various components in serum lipid, only LDL-C was independently associated with OSA.

Reduction in oxidative stress biomarkers after adenotonsillectomy

OBJECTIVES

A number of otolaryngic conditions such as chronic tonsillitis, adenoid hypertrophy, and obstructive sleep apnea are associated with oxidative stress and elevated levels of serum oxidants. The objective of this study is to measure changes in urine biomarkers of oxidative stress in children after adenotonsillectomy.

METHODS

Twenty-two children with sleep disordered breathing (SDB) with tonsil and adenoid hypertrophy were enrolled prior to adenotonsillectomy. Controls consisted of 20 healthy children. Urine samples were collected from all patients. Levels of three urinary biomarkers for oxidative status, 8-hydroxy-2-deoxyguanosine (8-OxodG), F(2)-isoprostane, and malondialdehyde (MDA) were measured using high performance liquid chromatography. For the study group, urine samples were repeated 3 weeks after surgery.

RESULTS

In the study group, preoperative urinary levels of 8-OxodG were higher than in controls (p=0.015). Levels decreased after surgery compared to preoperative levels (p=0.002), and reached control levels (p=0.167) at 3 weeks. Levels of urinary F(2)-isoprostane were similar in both groups (p=0.252), but decreased significantly after surgery (p=0.020).

CONCLUSIONS

Children with SDB have elevated levels of urinary 8-OxodG, a marker of oxidative stress. Adenotonsillectomy results in decreased 8-OxodG and F(2)-isoprostane. These findings suggest that urine analysis may represent a valuable tool for the measurement of oxidative stress.

The Association between Obstructive Sleep Apnea and Metabolic Markers and Lipid Profiles

PURPOSE

The purpose of this study was to investigate the association between apnea-hypopnea index (AHI) and metabolic markers and whether the elevated risk of Metabolic Syndrome (MetS) is related to Obstructive Sleep Apnea (OSA).

METHODS

This cross-sectional study recruited 246 male bus drivers from one transportation company in Taiwan. Each participant was evaluated by a polysomnography (PSG) test and by blood lipids examination. Severity of OSA was categorized according to the apnea-hypopnea index (AHI).

RESULTS

The results showed that a 73.3% prevalence of MetS in OSA (AHI > 15) and a 80.0% prevalence of MetS in severe OSA (AHI > 30) were found. After adjusting for confounding variables, an increased level of Body-Mass Index (BMI) and two non-MetS cardiovascular risk factors, total cholesterol/HDL-C ratio and TG/HDL-C ratio was significantly associated with AHI in subjects with severe OSA. MetS was about three times to be present in subjects with severe OSA, even adjusted for BMI.

CONCLUSIONS

The findings showed a high prevalence of MetS in OSA among professional drivers, especially in the severe group category. BMI was the major contributing factor to OSA. However, the present study did not find a sensitive clinical marker of a detrimental metabolic profile in OSA patients.

Obstructive sleep apnoea syndrome

Obstructive sleep apnoea syndrome (OSAS) is a common clinical condition in which the throat narrows or collapses repeatedly during sleep, causing obstructive sleep apnoea events. The syndrome is particularly prevalent in middle-aged and older adults. The mechanism by which the upper airway collapses is not fully understood but is multifactorial and includes obesity, craniofacial changes, alteration in upper airway muscle function, pharyngeal neuropathy and fluid shift towards the neck. The direct consequences of the collapse are intermittent hypoxia and hypercapnia, recurrent arousals and increase in respiratory efforts, leading to secondary sympathetic activation, oxidative stress and systemic inflammation. Excessive daytime sleepiness is a burden for the majority of patients. OSAS is also associated with cardiovascular co-morbidities, including hypertension, arrhythmias, stroke, coronary heart disease, atherosclerosis and overall increased cardiovascular mortality, as well as metabolic dysfunction. Whether treating sleep apnoea can fully reverse its chronic consequences remains to be established in adequately designed studies. Continuous positive airway pressure (CPAP) is the primary treatment modality in patients with severe OSAS, whereas oral appliances are also widely used in mild to moderate forms. Finally, combining different treatment modalities such as CPAP and weight control is beneficial, but need to be evaluated in randomized controlled trials. For an illustrated summary of this Primer, visit: http://go.nature.com/Lwc6te.

Abnormalities of lipoprotein concentrations in obstructive sleep apnea are related to insulin resistance

STUDY OBJECTIVE

Prevalence of cardiovascular disease (CVD) is increased in patients with obstructive sleep apnea (OSA), possibly related to dyslipidemia in these individuals. Insulin resistance is also common in OSA, but its contribution to dyslipidemia of OSA is unclear. The study's aim was to define the relationships among abnormalities of lipoprotein metabolism, clinical measures of OSA, and insulin resistance.

DESIGN

Cross-sectional study. OSA severity was defined by the apnea-hypopnea index (AHI) during polysomnography. Hypoxia measures were expressed as minimum and mean oxygen saturation, and the oxygen desaturation index. Insulin resistance was quantified by determining steady-state plasma glucose (SSPG) concentrations during the insulin suppression test. Fasting plasma lipid/lipoprotein evaluation was performed by vertical auto profile methodology.

SETTING

Academic medical center.

PARTICIPANTS

107 nondiabetic, overweight/obese adults.

MEASUREMENTS AND RESULTS

Lipoprotein particles did not correlate with AHI or any hypoxia measures, nor were there differences noted by categories of OSA severity. By contrast, even after adjustment for age, sex, and BMI, SSPG was positively correlated with triglycerides (r = 0.30, P < 0.01), very low density lipoprotein (VLDL) and its subclasses (VLDL1+2) (r = 0.21-0.23, P < 0.05), and low density lipoprotein subclass 4 (LDL4) (r = 0.30, P < 0.01). SSPG was negatively correlated with high density lipoprotein (HDL) (r = -0.38, P < 0.001) and its subclasses (HDL2 and HDL3) (r = -0.32, -0.43, P < 0.01), and apolipoprotein A1 (r = -0.33, P < 0.01). Linear trends of these lipoprotein concentrations across SSPG tertiles were also significant.

CONCLUSIONS

Pro-atherogenic lipoprotein abnormalities in obstructive sleep apnea (OSA) are related to insulin resistance, but not to OSA severity or degree of hypoxia. Insulin resistance may represent the link between OSA-related dyslipidemia and increased cardiovascular disease risk.

Mechanisms and clinical consequences of untreated central sleep apnea in heart failure

Central sleep apnea (CSA) is a highly prevalent, though often unrecognized, comorbidity in patients with heart failure (HF). Data from HF population studies suggest that it may present in 30% to 50% of HF patients. CSA is recognized as an important contributor to the progression of HF and to HF-related morbidity and mortality. Over the past 2 decades, an expanding body of research has begun to shed light on the pathophysiologic mechanisms of CSA. Armed with this growing knowledge base, the sleep, respiratory, and cardiovascular research communities have been working to identify ways to treat CSA in HF with the ultimate goal of improving patient quality of life and clinical outcomes. In this paper, we examine the current state of knowledge about the mechanisms of CSA in HF and review emerging therapies for this disorder.

Lipid profile after long-term APAP in OSA patients

PURPOSE

This study aimed to explore the impact of an 8-year therapy with autoadjusting positive airway pressure (APAP) on fasting lipid level in a sample of Portuguese moderate/severe obstructive sleep apnea (OSA) patients. Besides contributing to the comprehension of the complex relationship between dyslipidemia and OSA, it provided new data regarding the effectiveness of a long term APAP treatment.

METHODS

Thirty-nine male patients with moderate to severe OSA were included in the study. APAP was prescribed to all patients. Fifteen patients were under lipid-lowering medication throughout the study, and another 15 patients never used lipid-lowering medication at any time during the study. Fasting morning venous blood samples were collected at three time points (baseline 6 months and 8 years) and lipids were estimated. Statistical analysis was performed using Statistical Package for the Social Sciences (SPSS) 21.0 software.

RESULTS

After 8 years of APAP treatment, patients presented a similar body mass index but a significantly less severe daytime sleepiness. Patients on lipid-lowering medication exhibited a higher reduction in total cholesterol than those naïf from that medication, but the reduction was not statistically significant after adjusting for medication and APAP adherence.

CONCLUSIONS

Long-term APAP treatment improves OSA but does not seem to contribute to changes in fasting lipids.

Biomarkers to improve diagnosis and monitoring of obstructive sleep apnea syndrome: current status and future perspectives

Obstructive sleep apnea syndrome (OSAS) is characterized by recurrent episodes of upper airway collapse associated with oxygen desaturation and sleep disruption. It is proposed that these periodic changes lead to molecular variations that can be detected by assessing serum biomarkers. Studies have identified inflammatory, oxidative, and metabolic perturbations attributable to sleep-disordered breathing. Given that OSAS is associated with increased cardiovascular and cerebrovascular morbidity, the ideal biomarker should enable timely recognition with the possibility of intervention. There is accumulating data on the utility of serum biomarkers for the evaluation of disease severity, prognosis, and response to treatment. However, current knowledge is limited by data collection techniques, disease complexity, and potential confounding factors. The current paper reviews the literature on the use of serum biomarkers in OSAS. It is concluded that the ideal serum biomarker still needs to be discovered, while caution is needed in the interpretation of hitherto available results.