Increased adhesion molecules expression and production of reactive oxygen species in leukocytes of sleep apnea patients

Sleep disorders in chronic kidney disease

Sleep disorders are highly prevalent in chronic kidney disease (CKD) but are often under-recognized. Restless legs syndrome, which is common in CKD owing to issues with dopamine metabolism and is exacerbated by iron deficiency and uraemia, can lead to poor sleep quality and increased daytime fatigue. Insomnia is also prevalent in CKD, particularly in patients requiring dialysis, with increased sleep latency and sleep fragmentation being reported. The cause of insomnia in CKD is multifactorial - poor sleep habits and frequent napping during dialysis, uraemia, medications and mood disorders have all been suggested as potential contributing factors. Sleep apnoea and CKD are also now recognized as having a bi-directional relationship. Sleep apnoea is a risk factor for accelerated progression of CKD, and fluid overload, which is associated with kidney failure, can lead to both obstructive and central sleep apnoea. The presence of obstructive sleep apnoea in CKD can exacerbate the already heightened cardiovascular morbidity and mortality in these patients, as well as leading to daytime fatigue and reduced quality of life. Increased awareness, timely diagnosis and appropriate therapeutic interventions are essential to reduce the negative impact of sleep disorders in patients with kidney disease.

Effect of obstructive sleep apnea on postoperative delirium: a system review and meta-analysis

PURPOSE

To investigate the impact of obstructive sleep apnea (OSA) on postoperative delirium (PD), and evaluate the effectiveness of positive airway pressure (PAP) therapy on PD among OSA patients.

METHODS

We systematically searched Embase, Cochrane Library and PubMed databases from their establishment to November 27, 2022. A random-effects approach was employed to determine aggregated results. Subgroup and sensitivity analyses were carried out to investigate heterogeneity.

RESULTS

Sixteen eligible studies were included in the analysis. Thirteen studies revealed that OSA significantly elevated the likelihood of developing PD (OR = 1.71; 95%CI = 1.17 to 2.49; p = 0.005). Subgroup analysis according to delirium assessment scales showed that OSA did not exhibit an association with the incidence of PD assessed by the Confusion Assessment Method-Intensive Care Unit (OR = 1.14; 95%CI = 0.77 to 1.67; p = 0.51) but enhanced the likelihood of developing PD evaluated with other measurement scales (OR = 2.15; 95%CI = 1.44 to 3.19; p = 0.0002). Three additional studies explored the impact of PAP treatment on PD among OSA individuals, indicating no significant reduction in PD incidence with PAP use (OR = 0.58; 95%CI = 0.13 to 2.47; p = 0.46).

CONCLUSIONS

OSA may not be a risk factor for PD in critically ill patients in the intensive care unit, but may increase the likelihood of developing PD among individuals receiving regular care in the ward postoperatively. The efficacy of PAP therapy in decreasing PD incidence among OSA patients remains debatable.

IL6 Derived from Macrophages under Intermittent Hypoxia Exacerbates NAFLD by Promoting Ferroptosis via MARCH3-Led Ubiquitylation of GPX4

Obstructive sleep apnea (OSA) is a common sleep disorder characterized by intermittent hypoxia (IH) and is associated with the occurrence and development of nonalcoholic fatty liver disease (NAFLD). However, the specific mechanism by which OSA induces NAFLD remains unclear. Therefore, effective interventions are lacking. This study aims to investigate the role and mechanism of ferroptosis in OSA-related NAFLD using clinical data analyses, cell-based molecular experiments, and animal experiments. Indicators of liver function, lipid accumulation, and ferroptosis are also examined. RNA-seq, qPCR, western blotting, gene intervention, and E3 ligase prediction using UbiBrowser and co-IP are used to explore the potential underlying mechanisms. The results show that ferroptosis increases in the liver tissues of patients with OSA. Chronic IH promotes NAFLD progression in mice and is alleviated by a ferroptosis inhibitor Fer-1. The increased secretion of IL6 by macrophages can promote the expression of MARCH3 in hepatocytes under intermittent conditions, and subsequently promote the ubiquitination and degradation of GPX4 to regulate ferroptosis and lipid accumulation in hepatocytes. Hence, targeted inhibition of MARCH3 may alleviate IH-induced ferroptosis and lipid accumulation in liver tissues and inhibit the progression of NAFLD.

Renalase rs2296545 variant improve hypertension susceptibility by modifying binding affinity to catecholamines in obstructive sleep apnea

Obstructive sleep apnea (OSA), a condition often linked with hypertension, has an undefined relationship with renalase, a protein known for regulating blood pressure. This study aimed to investigate the relationship between serum renalase levels as well as renalase functional single nucleotide polymorphism (SNP) rs2296545 variant and hypertension in a Han Chinese OSA population. 126 subjects underwent serum renalase detection, with linear regression being performed to evaluate the relationship between serum renalase levels and OSA-related traits. Additional 4275 subjects were obtained rs2296545 genotype information by SNP microarray. And binary logistic regression was used to assess the effect of rs2296545 on hypertension risk. Molecular dynamics simulation and molecular docking were utilized to access the protein structures and the interplay between protein and catecholamines of wild-type and rs2296545 mutant renalase. The results showed that serum renalase levels were significantly higher in the severe OSA group. Further analysis showed renalase levels were positively correlated with blood pressure in the non-OSA group and negatively correlated in the severe OSA group. For rs2296545 polymorphism analysis, the hypertension risk significantly increased for the recessive model CC/GG + CG (OR = 1.211, 95% CI: 1.025-1.431) and the additive model CC/CG (OR = 1.223, 95% CI: 1.025-1.458) in the severe OSA. The rs2296545 polymorphism affected protein structure, and led to increase binding free energy, weakening interactions between renalase and catecholamines. In conclusion, serum renalase levels had independent association with blood pressure. And rs2296545 polymorphism may influence on susceptibility to hypertension by altering protein ability to bind to catecholamines, which might contribute to the intervention of hypertension in the OSA population.

The Association of Obstructive Sleep Apnea with Urological Cancer Incidence and Mortality-A Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVE

While obstructive sleep apnea (OSA) and urological cancer are both strongly associated with hypoxia, controversy exists regarding their association with each other. This study aims to summarize and synthesize evidence to clarify the association between OSA and urological cancer incidence and mortality.

METHODS

According to a prespecified protocol, PubMed, Embase, Cochrane Library, and Scopus were searched from inception to November 16, 2023, for observational and randomized studies reporting the association of OSA with urological cancer incidence or mortality. We pooled maximally covariate-adjusted hazard ratios (HRs) using a random-effects inverse variance-weighted model. Two reviewers independently assessed the quality of evidence using the Newcastle-Ottawa Scale and the Grading of Recommendations, Assessment, Development and Evaluation framework.

KEY FINDINGS AND LIMITATIONS

From 1814 records, we included 12 studies comprising 9 290 818 participants in total, of which nine studies were analyzed quantitatively. OSA patients had an increased risk of kidney (HR: 1.75, 95% confidence interval [CI]: 1.21-2.53) and bladder (HR: 1.76, 95% CI: 1.05-2.96) cancer. However, OSA was not associated with prostate cancer incidence (HR: 1.29, 95% CI: 0.82-2.04). We systematically reviewed evidence surrounding OSA and testicular cancer incidence and urological cancer mortality.

CONCLUSIONS AND CLINICAL IMPLICATIONS

OSA may be associated with a higher risk of kidney and bladder cancer, but not prostate cancer. Future work may help clarify the possibility of a dose-response relationship between OSA and urological cancer, and the effect of OSA treatment on urological cancer incidence or progression.

PATIENT SUMMARY

This research highlights a potential longitudinal association between OSA and kidney and bladder cancer, but not prostate cancer.

Molecular docking analysis of some medicinal extracts for pro-apoptotic, antiinflammatory and antioxidative activities using HCC cell lines

We investigated the biological activities of 14 medicinal plants from Saudi Arabia as anti-inflammatory, antioxidant and anti-proliferative properties using hepatocellular carcinoma (HCC) cell lines. Hexane extracts exhibited the maximum inhibitory activities against albumin denaturation compared with those of other solvents. Baccharoides schimperi hexane extract showed the highest anti-inflammatory while Ocimum basilicum methanol extract showed significantly high hydroxyl radical scavenging activity (p < 0.001). B. schimperi methanol extract showed highest cytotoxicity and anti-proliferation activity (IC50; 25 µg/ml) in hepatocellular carcinoma cell line. Annexin V and caspase-9 activities were induced significantly (p < 0.001) by B. schimperi and the response increased in a dose dependent compared with untreated cells (p < 0.001). The docking scores showed a low docking energy binding of 2-Cyclohexylpiperidine of B. schimperi with COX-2, (-16.62 kcal/mol), high affinity for apoptotic and anti-inflammatory potency It can be concluded that, B. schimperi active ingredients as 2-Cyclohexylpiperidine and phytol contributed to its biological activity.

Hypoxic and Autonomic Mechanisms from Sleep-Disordered Breathing Leading to Cardiopulmonary Dysfunction

Obstructive sleep apnea (OSA) is a common sleep-related breathing disorder. Its prevalence has increased due to increasing obesity and improved screening and diagnostic strategies. OSA overlaps with cardiopulmonary diseases to promote intermittent hypoxia and autonomic dysfunction. Intermittent hypoxia increases the risk for oxidative stress and inflammation, which promotes endothelial dysfunction and predisposes to atherosclerosis and other cardiovascular complications. OSA is associated with an increased sympathetic nervous system drive resulting in autonomic dysfunction leading to worsening of cardiopulmonary diseases. Cardiovascular diseases are observed in 40% to 80% of OSA patients. Therefore, it is essential to screen and treat cardiovascular diseases.

My voyage in the enchanted world of sleep

In this paper, I describe my 45-year career in sleep research. I started my undergraduate studies at Tel Aviv University, where I was first introduced to the enchanted world of sleep, continued to my graduate studies with Wilse B. Webb at the University of Florida, and then to post-doctoral training with Dan Kripke at the University of California at San Diego. Then, I describe the evolution of my academic career at the Technion-Israel Institute of Technology, where I started in 1975 as an Assistant Professor and retired in 2019 as the President of the Institute. I describe the areas of research that I pursued and how the research developed, emphasizing unexpected results that guided me and my lab team in new directions. This includes my early studies on ultradian rhythms, inspired by Nathaniel Kleitman's Basic Rest Activity Cyle hypothesis, utilizing the ultrashort sleep-wake paradigm to chart the 24-hour sleep propensity function, and how these studies led us to explore the role of melatonin in sleep regulation. I also explain why we directed our attention to sleep apnea, and how clinical observations led to the provocative hypothesis that sleep apnea-typically seen as a disorder-may also play a protective role. Under the leadership of my research partner and wife, Lena, we confirmed this hypothesis. Also in this article, I describe my enthusiasm for the history of our field and, as derived from my experience as a Dean of Medicine and President of a university, I share my philosophy about the role of members of academia in society. I emphasize that none of my achievements could have been accomplished without the hard work and motivation of my students and research partners, who shared my enthusiasm and passion for the enchanted world of sleep. This paper is part of the Living Legends in Sleep Research series, which is sponsored by Idorsia Pharmaceuticals and Jazz Pharmaceuticals.

Whole blood coagulation in an ex vivo thrombus is sufficient to induce clot neutrophils to adopt a myeloid-derived suppressor cell signature and shed soluble Lox-1

BACKGROUND

Blood clots are living tissues that release inflammatory mediators including IL-8/CXCL8 and MCP-1/CCL2. A deeper understanding of blood clots is needed to develop new therapies for prothrombotic disease states and regenerative medicine.

OBJECTIVES

To identify a common transcriptional shift in cultured blood clot leukocytes.

METHODS

Differential gene expression of whole blood and cultured clots (4 hours at 37 °C) was assessed by RNA sequencing (RNAseq), reverse transcriptase-polymerase chain reaction, proteomics, and histology (23 diverse healthy human donors). Cultured clot serum bioactivity was tested in endothelial barrier functional assays.

RESULTS

All cultured clots developed a polymorphonuclear myeloid-derived suppressor cell (PMN-MDSC) signature, including up-regulation of OLR1 (mRNA encoding lectin-like oxidized low-density lipoprotein receptor 1 [Lox-1]), IL-8/CXCL8, CXCL2, CCL2, IL10, IL1A, SPP1, TREM1, and DUSP4/MKP. Lipopolysaccharide enhanced PMN-MDSC gene expression and specifically induced a type II interferon response with IL-6 production. Lox-1 was specifically expressed by cultured clot CD15+ neutrophils. Cultured clot neutrophils, but not activated platelets, shed copious amounts of soluble Lox-1 (sLox-1) with a donor-dependent amplitude. sLox-1 shedding was enhanced by phorbol ester and suppressed by heparin and by beta-glycerol phosphate, a phosphatase inhibitor. Cultured clot serum significantly enhanced endothelial cell monolayer barrier function, consistent with a proresolving bioactivity.

CONCLUSION

This study suggests that PMN-MDSC activation is part of the innate immune response to coagulation which may have a protective role in inflammation. The cultured blood clot is an innovative thrombus model that can be used to study both sterile and nonsterile inflammatory states and could be used as a personalized medicine tool for drug screening.

Composite dietary antioxidant index and sleep health: a new insight from cross-sectional study

BACKGROUND

Low-quality sleep and obstructive sleep apnea (OSA) can result in series of chronic diseases. Healthy diet has been considered as an effective and simple strategy to optimize sleep quality. However, current evidence on the correlation of dietary composite antioxidant intake with sleep health remained obscure.

AIM OF THE STUDY

To determine the relationship of composite dietary antioxidant index (CDAI) and sleep health.

METHODS

Cross-sectional analyses were based on National Health and Nutrition Examination Survey (NHANES) 2005-2008. Dietary consumption was assessed by trained staff using 24-h diet recall method and CDAI was calculated based on previous validated approach that included six antioxidants. Sleep-related outcomes were self-reported by a set of questionnaires and classified into OSA, day sleepiness, and insufficient sleep. Weighted logistic regression was conducted to calculate odds ratios (ORs) and 95% confidence intervals (CIs). Restricted cubic spline (RCS) regressions were also used to evaluate the dose-response of CDAI and three sleep-related outcomes.

RESULTS

A total of 7274 subjects included (mean age: 46.97 years) were enrolled in our study, including 3658 were females (52.54%) and 3616 were males (47.46%). Of them, 70.6%, 29.51%, and 35.57% of the subjects reported that they had OSA, day sleepiness and insufficient sleep, respectively. Logistic regression showed the highest quartile of CDAI was inversely associated with the risk of OSA (OR: 0.69, 95%CI: 0.49-0.97), day sleepiness (OR: 0.64, 95%CI: 0.44-0.94) and insufficient sleep (OR: 0.68, 95%CI: 0.50-0.92) compared with the lowest quartile. RCS showed linear relationship of CDAI and insufficient sleep but non-linear relationship of CDAI with OSA and day sleepiness.

CONCLUSIONS

Our results show that CDAI was non-linearly associated with lower risk of OSA and day sleepiness whereas a linear inverse association between CDAI and insufficient sleep was observed. These findings implicate that combined intake of antioxidants could be a promising and effective approach to optimize sleep quality for public.

Obstructive Sleep Apnea-Associated Intermittent Hypoxia-Induced Immune Responses in Males, Pregnancies, and Offspring

Obstructive sleep apnea (OSA), a respiratory sleep disorder associated with cardiovascular diseases, is more prevalent in men. However, OSA occurrence in pregnant women rises to a level comparable to men during late gestation, creating persistent effects on both maternal and offspring health. The exact mechanisms behind OSA-induced cardiovascular diseases remain unclear, but inflammation and oxidative stress play a key role. Animal models using intermittent hypoxia (IH), a hallmark of OSA, reveal several pro-inflammatory signaling pathways at play in males, such as TLR4/MyD88/NF-κB/MAPK, miRNA/NLRP3, and COX signaling, along with shifts in immune cell populations and function. Limited evidence suggests similarities in pregnancies and offspring. In addition, suppressing these inflammatory molecules ameliorates IH-induced inflammation and tissue injury, providing new potential targets to treat OSA-associated cardiovascular diseases. This review will focus on the inflammatory mechanisms linking IH to cardiovascular dysfunction in males, pregnancies, and their offspring. The goal is to inspire further investigations into the understudied populations of pregnant females and their offspring, which ultimately uncover underlying mechanisms and therapeutic interventions for OSA-associated diseases.

Interventional management of mitral regurgitation and sleep disordered breathing: "Catching two birds with one stone"

Sleep disordered breathing (SDB), mostly constituting of obstructive and central sleep apnea (OSA and CSA, respectively), is highly prevalent in the general population, and even more among patients with cardiovascular disease, heart failure (HF) and valvular heart disease, such as mitral regurgitation (MR). The coexistence of HF, MR and SDB is associated with worse cardiovascular outcomes and increased morbidity and mortality. Pulmonary congestion, as a result of MR, can exaggerate and worsen the clinical status and symptoms of SDB, while OSA and CSA, through various mechanisms that impair left ventricular dynamics, can promote left ventricular remodelling, mitral annulus dilatation and consequently MR. Regarding treatment, positive airway pressure devices used to ameliorate symptoms in SDB also seem to result in a reduction of MR severity, MR jet fraction and an improvement of left ventricular ejection fraction. However, surgical and transcatheter interventions for MR, and especially transcatheter edge to edge mitral valve repair (TEER), seem to also have a positive effect on SDB, by reducing OSA and CSA-related severity indexes and improving symptom control. The purpose of this review is to provide a comprehensive analysis of the common pathophysiology between SDB and MR, as well as to discuss the available evidence regarding the effect of SDB treatment on MR and the effect of mitral valve surgery or transcatheter repair on both OSA and CSA.

Obstructive Sleep Apnea and Its Influence on Intracranial Aneurysm

Obstructive sleep apnea syndrome (OSAS) is associated with cerebrovascular disease, which can lead to life-threatening outcomes. The purpose of the study was to investigate the relationship between OSAS and comorbid intracranial aneurysms. We retrospectively reviewed 564 patients who underwent a polysomnography and brain magnetic resonance angiography as part of their health checkup. We calculated the prevalence of an intracranial aneurysm and OSAS in patients and measured the size of the intracranial aneurysm if present. The mean patient age was 55.6 ± 8.5 years, and 82.3% of them were men. The prevalence of an intracranial aneurysm in patients with OSAS was 12.1%, which is significantly higher than patients with non-OSAS (5.9%, p = 0.031). Patients with OSAS had a much higher prevalence of intracranial aneurysms, after adjusting all possible confounding factors such as age, sex, smoking status, alcohol drinking, and body mass index (odds ratio: 2.32; 95% confidence interval: 1.07-5.04). Additionally, the OSAS group had noticeably larger aneurysms compared with those of the non-OSAS group (3.2 ± 2.0 mm vs. 2.0 ± 0.4 mm, p = 0.013). We found a significant association between OSAS and intracranial aneurysms. OSAS could be another risk factor for the development of intracranial aneurysms.

Exploring the potential relationships among obstructive sleep apnea, erectile dysfunction, and gut microbiota: a narrative review

INTRODUCTION

Poor sleep quality is closely associated with comorbidities affecting a multitude of organ systems. Among the sleep disorders in the population, there has recently been an increase in the prevalence of obstructive sleep apnea (OSA), which has particularly affected men. The intermittent hypoxia and sleep fragmentation associated with OSA can result in the manifestation or aggravation of a number of pathophysiologic conditions, including the impairment of reproductive function in men and women. In this context, erectile dysfunction (ED) is of particular concern. Other consequences of OSA are changes in the gastrointestinal microbiota, with the resultant dysbiosis having potentially harmful consequences that promote downstream exacerbation of various comorbidities.

OBJECTIVES

This narrative review aims to explore the potential relationships among ED, gut microbiota, and OSA.

METHODS

A search of the relevant literature was performed in the PubMed, Embase, Medline, and Web of Science databases.

RESULTS

Sleep is important for regulating the body's functions, and sleep deprivation can negatively affect health. OSA can damage organic functions, including reproductive function, and can lead to ED. Restoring the microbiota and improving sleep can help to improve sexual function or reverse ED and enhance other associated conditions mediated through the gut-brain axis relationship. Probiotics and prebiotics can be used as supportive strategies in the prevention and treatment of OSA, as they help to reduce systemic inflammation and improve intestinal barrier function.

CONCLUSION

A good diet, a healthy lifestyle, and proper bowel function are essential in controlling depression and several other pathologies. Modulating the gut microbiota through probiotics and prebiotics can provide a viable strategy for developing new therapeutic options in treating many conditions. A better understanding of these a priori unrelated phenomena would foster our understanding of the effects of OSA on human fertility and how changes in gut microbiota may play a role.

The immune response to arterial damage in a mouse model of intermittent hypoxia: a transcriptomics analysis

PURPOSE

Mice can develop arterial damage and even atherosclerosis under intermittent hypoxia (IH); however, the specific mechanism of arterial damage induced by IH remains unclear. Hence, this research aimed to illustrate the underlying mechanism linking IH to arterial injury.

MATERIALS AND METHODS

The differential gene expression of the thoracic aorta under normoxia or IH mice was analyzed utilizing RNA sequencing. Furthermore, GO, KEGG pathway, and CIBERSORT analyses were carried out. For verification of the expression of candidate genes affected by IH, quantitative RT-qPCR (qRT-PCR) was conducted. Immunohistochemical (IHC) staining revealed immune cell infiltration in the thoracic aorta.

RESULTS

The thickness of the intima-media of the mouse aorta was increased, and the fiber structure was disordered under IH. Transcriptomics analysis showed that in the aorta, 1137 upregulated genes and 707 downregulated genes were affected by IH, significantly related to the activation of the immune system and cell adhesion. Furthermore, B cell infiltration around the aorta was observed under IH.

CONCLUSIONS

IH might lead to structural changes in the aorta by activating the immune response and enhancing cell adhesion.

Loss of heme oxygenase 2 causes reduced expression of genes in cardiac muscle development and contractility and leads to cardiomyopathy in mice

Obstructive sleep apnea (OSA) is a common breathing disorder that affects a significant portion of the adult population. In addition to causing excessive daytime sleepiness and neurocognitive effects, OSA is an independent risk factor for cardiovascular disease; however, the underlying mechanisms are not completely understood. Using exposure to intermittent hypoxia (IH) to mimic OSA, we have recently reported that mice exposed to IH exhibit endothelial cell (EC) activation, which is an early process preceding the development of cardiovascular disease. Although widely used, IH models have several limitations such as the severity of hypoxia, which does not occur in most patients with OSA. Recent studies reported that mice with deletion of hemeoxygenase 2 (Hmox2-/-), which plays a key role in oxygen sensing in the carotid body, exhibit spontaneous apneas during sleep and elevated levels of catecholamines. Here, using RNA-sequencing we investigated the transcriptomic changes in aortic ECs and heart tissue to understand the changes that occur in Hmox2-/- mice. In addition, we evaluated cardiac structure, function, and electrical properties by using echocardiogram and electrocardiogram in these mice. We found that Hmox2-/- mice exhibited aortic EC activation. Transcriptomic analysis in aortic ECs showed differentially expressed genes enriched in blood coagulation, cell adhesion, cellular respiration and cardiac muscle development and contraction. Similarly, transcriptomic analysis in heart tissue showed a differentially expressed gene set enriched in mitochondrial translation, oxidative phosphorylation and cardiac muscle development. Analysis of transcriptomic data from aortic ECs and heart tissue showed loss of Hmox2 gene might have common cellular network footprints on aortic endothelial cells and heart tissue. Echocardiographic evaluation showed that Hmox2-/- mice develop progressive dilated cardiomyopathy and conduction abnormalities compared to Hmox2+/+ mice. In conclusion, we found that Hmox2-/- mice, which spontaneously develop apneas exhibit EC activation and transcriptomic and functional changes consistent with heart failure.

The effect of continuous positive airway pressure on total antioxidant capacity in obstructive sleep apnea: a systematic review and meta-analysis

BACKGROUND

Obstructive sleep apnea (OSA), a sleep-related disorder with high prevalence, is associated with an imbalance in oxidative stress and is linked to cardiovascular disease. There are conflicting reports regarding the effectiveness of continuous positive airway pressure (CPAP) therapy on oxidative stress/antioxidant markers in patients with OSA. This review was performed to evaluate the influence of therapy with CPAP on serum/plasma total antioxidant capacity (TAC) in patients with OSA.

METHODS

The Cochrane Library, Web of Science, Scopus, Embase, and PubMed were searched through June 2022 to obtain studies evaluating CPAP treatment on TAC in patients with OSA. Overall results were tested using standardized mean difference (SMD) with a 95% confidence interval (CI). Comprehensive Meta-Analysis V2 software was employed to perform analyses.

RESULTS

Ten studies with 12 effect sizes were eligible for inclusion in this analysis. The overall SMD revealed that CPAP therapy significantly increased TAC [SMD 0.497; 95% CI: 0.21 to 0.77; p: 0.00] in OSA. Analyses based on subgroups showed that the effect of CPAP therapy was significant in all subgroups according to therapy duration, age, BMI, and AHI. Whereas the meta-regression results indicated that the impact of therapy with CPAP on TAC is associated with AHI, BMI, and age in patients with OSA.

CONCLUSIONS

The finding of this meta-analysis demonstrated a favorable impact of CPAP therapy on TAC levels in patients suffering from OSA.

Pathophysiological mechanisms and therapeutic approaches in obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is a common breathing disorder in sleep in which the airways narrow or collapse during sleep, causing obstructive sleep apnea. The prevalence of OSAS continues to rise worldwide, particularly in middle-aged and elderly individuals. The mechanism of upper airway collapse is incompletely understood but is associated with several factors, including obesity, craniofacial changes, altered muscle function in the upper airway, pharyngeal neuropathy, and fluid shifts to the neck. The main characteristics of OSAS are recurrent pauses in respiration, which lead to intermittent hypoxia (IH) and hypercapnia, accompanied by blood oxygen desaturation and arousal during sleep, which sharply increases the risk of several diseases. This paper first briefly describes the epidemiology, incidence, and pathophysiological mechanisms of OSAS. Next, the alterations in relevant signaling pathways induced by IH are systematically reviewed and discussed. For example, IH can induce gut microbiota (GM) dysbiosis, impair the intestinal barrier, and alter intestinal metabolites. These mechanisms ultimately lead to secondary oxidative stress, systemic inflammation, and sympathetic activation. We then summarize the effects of IH on disease pathogenesis, including cardiocerebrovascular disorders, neurological disorders, metabolic diseases, cancer, reproductive disorders, and COVID-19. Finally, different therapeutic strategies for OSAS caused by different causes are proposed. Multidisciplinary approaches and shared decision-making are necessary for the successful treatment of OSAS in the future, but more randomized controlled trials are needed for further evaluation to define what treatments are best for specific OSAS patients.

An integrated multi-omics analysis of sleep-disordered breathing traits implicates P2XR4 purinergic signaling

Sleep Disordered Breathing (SDB) is a common disease associated with increased risk for cardiometabolic, cardiovascular, and cognitive diseases. How SDB affects the molecular environment is still poorly understood. We study the association of three SDB measures with gene expression measured using RNA-seq in multiple blood tissues from the Multi-Ethnic Study of Atherosclerosis. We develop genetic instrumental variables for the associated transcripts as polygenic risk scores (tPRS), then generalize and validate the tPRS in the Women's Health Initiative. We measure the associations of the validated tPRS with SDB and serum metabolites in Hispanic Community Health Study/Study of Latinos. Here we find differential gene expression by blood cell type in relation to SDB traits and link P2XR4 expression to average oxyhemoglobin saturation during sleep and butyrylcarnitine (C4) levels. These findings can be used to develop interventions to alleviate the effect of SDB on the human molecular environment.

Cardiovascular Disease in Obstructive Sleep Apnea: Putative Contributions of Mineralocorticoid Receptors

Obstructive sleep apnea (OSA) is a chronic and highly prevalent condition that is associated with oxidative stress, inflammation, and fibrosis, leading to endothelial dysfunction, arterial stiffness, and vascular insulin resistance, resulting in increased cardiovascular disease and overall mortality rates. To date, OSA remains vastly underdiagnosed and undertreated, with conventional treatments yielding relatively discouraging results for improving cardiovascular outcomes in OSA patients. As such, a better mechanistic understanding of OSA-associated cardiovascular disease (CVD) and the development of novel adjuvant therapeutic targets are critically needed. It is well-established that inappropriate mineralocorticoid receptor (MR) activation in cardiovascular tissues plays a causal role in a multitude of CVD states. Clinical studies and experimental models of OSA lead to increased secretion of the MR ligand aldosterone and excessive MR activation. Furthermore, MR activation has been associated with worsened OSA prognosis. Despite these documented relationships, there have been no studies exploring the causal involvement of MR signaling in OSA-associated CVD. Further, scarce clinical studies have exclusively assessed the beneficial role of MR antagonists for the treatment of systemic hypertension commonly associated with OSA. Here, we provide a comprehensive overview of overlapping mechanistic pathways recruited in the context of MR activation- and OSA-induced CVD and propose MR-targeted therapy as a potential avenue to abrogate the deleterious cardiovascular consequences of OSA.

The Use of Continuous Positive Airway Pressure for Patients With Obstructive Sleep Apnea is Associated With Early Medical and Surgery-Related Complications Following Total Knee Arthroplasty: A National Database Study

Background

Obstructive sleep apnea (OSA) has been shown to increase the risk of complications following total knee arthroplasty (TKA) although prior studies were limited by their ability to stratify OSA patients by disease severity. The objective of this study was to determine the effect size of the use of continuous positive airway pressure (CPAP) on early medical and surgery-related complications following TKA among patients with OSA.

Methods

Patients with OSA who underwent primary TKA were identified using the PearlDiver Mariner database. Ninety-day incidences of medical complications and 1-year incidences of surgery-related complications as well as hospital utilization were evaluated for OSA patients who had used CPAP prior to TKA compared to those who did not.

Results

CPAP patients were at increased 90-day risk of emergency department presentation (odds ratio [OR] 1.61; P < .0001), hospital admission (OR 1.33; P < .001), ICU admission (OR 1.45, P < .0001), pulmonary embolism (OR 1.68, P < .0001), deep vein thrombosis (OR 1.31, P < .0001), transfusion (OR 1.89, P < .0001), pneumonia (OR 1.63, P < .0001), cerebrovascular accident (OR 1.92, P < .0001), myocardial infarction (OR 1.57, P = .0015), sepsis (OR 1.35, P = .0025), blood loss anemia (OR 1.67, P < .0001), acute kidney injury (OR 1.65, P < .0001), and urinary tract infection (OR 1.99, P < .0001), as well as increased 1-year risk of undergoing revision surgery (OR 1.14, P = .0028), compared to OSA patients not using CPAP.

Conclusions

OSA patients on CPAP undergoing TKA have significantly increased complication rates compared to OSA patients not using CPAP.

Level of Evidence

III, Retrospective review.

Retinal Microvascular Abnormalities and Systemic Arterial Stiffness Are the First Manifestation of Cardiovascular Abnormalities in Patients with Untreated Moderate to Severe Obstructive Sleep Apnoea and with Low to Intermediate Cardiovascular Risk-A Pilot Study

This study aimed to investigate macro- and microvascular function parameters and their relationship with known markers of cardiovascular risk in patients with untreated moderate to severe obstructive sleep apnoea (OSA). Fourteen patients with moderate to severe OSA and fourteen controls were included in the present study. General assessments included BMI, systemic blood pressure (BP) and circulating markers for oxidative stress and endothelial function. Additional assessments included 24 h BP and heart rate monitoring, as well as the assessment of heart rate variability. Macro- and microvascular assessments included augmentation index, carotid intima-media thickness, brachial artery flow-mediated dilation, as well as various retinal microvascular function assessments, using the Dynamic Retinal Vessel Analyzer. All participants completed the Short Form Health Survey, Functional Outcomes of Sleep Questionnaire, and Epworth Sleepiness Scale. The results show that, in comparison to controls, BMI (p = 0.003) and AIx (p = 0.025) were significantly higher in the OSA group. There was, however, no significant difference between groups with regard to other measured systemic general, vascular and circulatory parameters (all p > 0.05). Nevertheless, the retinal microvascular function showed various alterations in the OSA patients, including a delayed reaction time in response to flicker (p = 0.047), as well as a decreased dilation amplitude (p = 0.004), dilation slope (p = 0.004), and post-flicker constriction (p = 0.015). In addition, the observed SlopeAD alterations correlated negatively with BMI values only in the OSA group (r = −0.46, p = 0.045). In conclusion, individuals with untreated moderate to severe OSA but without overt CVD, exhibit signs of increased arterial stiffness and retinal microvascular dysfunction, which can be early indicators for future vascular complications.

Intermittent hypoxia inhibits epinephrine-induced transcriptional changes in human aortic endothelial cells

Obstructive sleep apnea (OSA) is an independent risk factor for cardiovascular disease. While intermittent hypoxia (IH) and catecholamine release play an important role in this increased risk, the mechanisms are incompletely understood. We have recently reported that IH causes endothelial cell (EC) activation, an early phenomenon in the development of cardiovascular disease, via IH-induced catecholamine release. Here, we investigated the effects of IH and epinephrine on gene expression in human aortic ECs using RNA-sequencing. We found a significant overlap between IH and epinephrine-induced differentially expressed genes (DEGs) including enrichment in leukocyte migration, cytokine-cytokine receptor interaction, cell adhesion and angiogenesis. Epinephrine caused higher number of DEGs compared to IH. Interestingly, IH when combined with epinephrine had an inhibitory effect on epinephrine-induced gene expression. Combination of IH and epinephrine induced MT1G (Metallothionein 1G), which has been shown to be highly expressed in ECs from parts of aorta (i.e., aortic arch) where atherosclerosis is more likely to occur. In conclusion, epinephrine has a greater effect than IH on EC gene expression in terms of number of genes and their expression level. IH inhibited the epinephrine-induced transcriptional response. Further investigation of the interaction between IH and epinephrine is needed to better understand how OSA causes cardiovascular disease.

Assessment of sleep disordered breathing in patients with heart failure

When to look for sleep disturbances in heart failure patients and how best to treat them: a practical and evidence-based expert opinion https://bit.ly/3LpCnNP.

Intermittent Hypoxia and Atherosclerosis: From Molecular Mechanisms to the Therapeutic Treatment

Intermittent hypoxia (IH) has a dual nature. On the one hand, chronic IH (CIH) is an important pathologic feature of obstructive sleep apnea (OSA) syndrome (OSAS), and many studies have confirmed that OSA-related CIH (OSA-CIH) has atherogenic effects involving complex and interacting mechanisms. Limited preventive and treatment methods are currently available for this condition. On the other hand, non-OSA-related IH has beneficial or detrimental effects on the body, depending on the degree, duration, and cyclic cycle of hypoxia. It includes two main states: intermittent hypoxia in a simulated plateau environment and intermittent hypoxia in a normobaric environment. In this paper, we compare the two types of IH and summarizes the pathologic mechanisms and research advances in the treatment of OSA-CIH-induced atherosclerosis (AS), to provide evidence for the systematic prevention and treatment of OSAS-related AS.

Protein phosphatase 1 regulates reactive oxygen species-dependent degradation of histone deacetylase 5 by intermittent hypoxia

We recently reported pheochromocytoma 12 (PC12) cells and rats subjected to intermittent hypoxia (IH), a hallmark manifestation of obstructive sleep apnea (OSA), exhibit reduced histone deacetylase activity and HDAC5 protein. Our study further suggested that posttranslational modifications rather than transcriptional mechanism(s) mediate IH-induced HDAC5 degradation. These observations prompted our current study to investigate the mechanism(s) underlying HDAC5 degradation by IH in PC12 cell cultures. IH-induced HDAC5 degradation was blocked by an antioxidant, and reactive oxygen species (ROS) mimetics decreased HDAC5 protein, suggesting that ROS mediates HDAC5 degradation by IH. NADPH oxidases (NOX) 2 and 4 were identified as sources of ROS that mediate the effects of IH. HDAC5 degradation during IH was associated with dephosphorylation of HDAC5 at serine²⁵⁹, and this response was blocked by a NOX inhibitor, suggesting that ROS-dependent dephosphorylation mediates HDAC5 degradation. IH-induced dephosphorylation of HDCA5 was inhibited by calyculin A, an inhibitor of protein phosphatase (PP)-1 and -2, or by the overexpression of nuclear inhibitor of PP1 (NIPP1). HDAC5 dephosphorylation by IH lead to augmented hypoxia-inducible factor (HIF)-1α protein and an increase in its transcriptional activity. These data suggest that PP1-dependent dephosphorylation of S²⁵⁹ destabilizes HDAC5 protein in response to IH, resulting in HIF-1α stabilization and transcriptional activity. Our findings highlight hither to unexplored role of protein phosphatases, especially PP1 in regulating HDAC5 protein, which is an upstream activator of HIF-1 signaling by IH.

PAI-1: A Major Player in the Vascular Dysfunction in Obstructive Sleep Apnea?

Obstructive sleep apnea is a chronic and prevalent condition that is associated with endothelial dysfunction, atherosclerosis, and imposes excess overall cardiovascular risk and mortality. Despite its high prevalence and the susceptibility of CVD patients to OSA-mediated stressors, OSA is still under-recognized and untreated in cardiovascular practice. Moreover, conventional OSA treatments have yielded either controversial or disappointing results in terms of protection against CVD, prompting the need for the identification of additional mechanisms and associated adjuvant therapies. Plasminogen activator inhibitor-1 (PAI-1), the primary inhibitor of tissue-type plasminogen activator (tPA) and urinary-type plasminogen activator (uPA), is a key regulator of fibrinolysis and cell migration. Indeed, elevated PAI-1 expression is associated with major cardiovascular adverse events that have been attributed to its antifibrinolytic activity. However, extensive evidence indicates that PAI-1 can induce endothelial dysfunction and atherosclerosis through complex interactions within the vasculature in an antifibrinolytic-independent matter. Elevated PAI-1 levels have been reported in OSA patients. However, the impact of PAI-1 on OSA-induced CVD has not been addressed to date. Here, we provide a comprehensive review on the mechanisms by which OSA and its most detrimental perturbation, intermittent hypoxia (IH), can enhance the transcription of PAI-1. We also propose causal pathways by which PAI-1 can promote atherosclerosis in OSA, thereby identifying PAI-1 as a potential therapeutic target in OSA-induced CVD.

The relation of dietary components with severity of obstructive sleep apnea in Cypriot patients: A randomized, stratified epidemiological study

Background

Obstructive Sleep Apnea (OSA) is considered a public health problem and its prevalence is increasing at an epidemic rate. The aim of this study was to examine whether individual nutrients (macronutrients, antioxidant vitamins) rather than energy restriction may potentially affect OSA severity in a representative population of Cyprus.

Methods

A total sample of 303 adults (>18 years old) with Cypriot citizenship and permanently residing in Cyprus were randomly selected. Selected patients have completed the food frequency questionnaire, and a physical activity questionnaire and underwent a sleep study to assess OSA severity.

Results

Overall, 303 patients were included in this study, 169 (55.8%) had mild OSA (apnea-hypopnea index—AHI <15) and the remaining 83 (27.4%) had moderate to severe OSA (AHI>15). The mean age of all patients was 55.7 years old. Patients with moderate to severe OSA had significant higher BMI levels, higher consumption of calories, higher hip circumference, waist circumference, waist-hip ratio and neck circumference and higher consumption of folic acid compared with the patients with mild OSA (p<0.05).

Conclusions

The findings suggest that increased energy intake regardless diet macronutrient composition is positively associated with OSA severity whereas higher folic acid intake seems to have a protective role.

Intermittent hypoxia and sleep disruption in obstructive sleep apnea increase serum tau and amyloid-beta levels

Obstructive sleep apnea is characterized by intermittent hypoxia and sleep disruption, leading to accelerated neurodegenerative changes and cognitive decline. Serum amyloid-beta and tau proteins, which are markers for Alzheimer's disease, have been reported to increase in patients with obstructive sleep apnea. This study compared the serum levels of amyloid-beta proteins and tau proteins in 46 cognitively normal obstructive sleep apnea patients and 30 healthy controls. Sleep parameters and severity of obstructive sleep apnea were determined using overnight polysomnography. Serum levels of Aβ40, Aβ42, total tau and phosphorylated-tau were determined by enzyme-linked immunosorbent assay. Patients with obstructive sleep apnea had significantly higher median serum levels of Aβ40 (121.0 versus 78.3 pg ml^-1 ), Aβ42 (105.6 versus 18.6 pg ml^-1 ) and total tau (168.5 versus 10.9 pg ml^-1 ) than controls. Serum levels of phosphorylated-tau did not differ significantly between the two groups. Serum levels of amyloid and tau proteins correlated with parameters of nocturnal oxygen saturation. Rapid eye movement sleep was negatively correlated with total amyloid-beta proteins. We conclude that serum levels of amyloid-beta and total tau are higher in patients with obstructive sleep apnea and hypoxia as well as changes in sleep architecture associated with their increased levels. Patients with obstructive sleep apnea should be closely monitored for the signs of cognitive impairment. Obstructive sleep apnea is a modifiable risk factor, and its treatment may reverse neurodegenerative changes and prevent cognitive impairment.

Enhanced Cardiac CaMKII Oxidation and CaMKII-Dependent SR Ca Leak in Patients with Sleep-Disordered Breathing

Background: Sleep-disordered breathing (SDB) is associated with increased oxidant generation. Oxidized Ca/calmodulin kinase II (CaMKII) can contribute to atrial arrhythmias by the stimulation of sarcoplasmic reticulum Ca release events, i.e., Ca sparks. Methods: We prospectively enrolled 39 patients undergoing cardiac surgery to screen for SDB and collected right atrial appendage biopsies. Results: SDB was diagnosed in 14 patients (36%). SDB patients had significantly increased levels of oxidized and activated CaMKII (assessed by Western blotting/specific pulldown). Moreover, SDB patients showed a significant increase in Ca spark frequency (CaSpF measured by confocal microscopy) compared with control subjects. CaSpF was 3.58 ± 0.75 (SDB) vs. 2.49 ± 0.84 (no SDB) 1/100 µm⁻¹s⁻¹ (p < 0.05). In linear multivariable regression models, SDB severity was independently associated with increased CaSpF (B [95%CI]: 0.05 [0.03; 0.07], p < 0.001) after adjusting for important comorbidities. Interestingly, 30 min exposure to the CaMKII inhibitor autocamtide-2 related autoinhibitory peptide normalized the increased CaSpF and eliminated the association between SDB and CaSpF (B [95%CI]: 0.01 [−0.1; 0.03], p = 0.387). Conclusions: Patients with SDB have increased CaMKII oxidation/activation and increased CaMKII-dependent CaSpF in the atrial myocardium, independent of major clinical confounders, which may be a novel target for treatment of atrial arrhythmias in SDB.

Obstructive Sleep apnea and cardiovascular events in Elderly Patients

INTRODUCTION

In recent decades, life expectancy has increased considerably. The cardiovascular effects of Obstructive Sleep Apnea (OSA) in the elderly lead to patient disability and high resource consumption. Intermittent nocturnal hypoxia leads to hemodynamic stress and adrenergic activation, which promotes cardiovascular disease. However, chronic intermittent hypoxia may protect elderly patients from cardiovascular events (CVE) due to biological adaptation.

AREAS COVERED

OSA patients are at increased risk of cardiovascular events. The severity of OSA increases cardiovascular risk, and this association also exists in the elderly. This article reviews the association between OSA, CPAP treatment, and CVE, particularly stroke and coronary heart disease (CHD), in the elderly. MEDLINE and the Cochrane Collaboration databases were searched from inception to July 2021.

EXPERT COMMENTARY

Although a positive association between OSA and the incidence of cardiovascular disease in the elderly has been established, the role of sleep apnea in certain cardiovascular events remains controversial. Most authors agree that untreated OSA is a risk factor for stroke or worse stroke prognosis. However, the association between OSA and CHD is usually less pronounced than between OSA and stroke, especially in the elderly.

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.

Identification of key genes and immune infiltration modulated by CPAP in obstructive sleep apnea by integrated bioinformatics analysis

Patients with obstructive sleep apnea (OSA) experience partial or complete upper airway collapses during sleep resulting in nocturnal hypoxia-normoxia cycling, and continuous positive airway pressure (CPAP) is the golden treatment for OSA. Nevertheless, the exact mechanisms of action, especially the transcriptome effect of CPAP on OSA patients, remain elusive. The goal of this study was to evaluate the longitudinal alterations in peripheral blood mononuclear cells transcriptome profiles of OSA patients in order to identify the hub gene and immune response. GSE133601 was downloaded from Gene Expression Omnibus (GEO). We identified black module via weighted gene co-expression network analysis (WGCNA), the genes in which were correlated significantly with the clinical trait of CPAP treatment. Finally, eleven hub genes (TRAV10, SNORA36A, RPL10, OBP2B, IGLV1-40, H2BC8, ESAM, DNASE1L3, CD22, ANK3, ACP3) were traced and used to construct a random forest model to predict therapeutic efficacy of CPAP in OSA with a good performance with AUC of 0.92. We further studied the immune cells infiltration in OSA patients with CIBERSORT, and monocytes were found to be related with the remission of OSA and partially correlated with the hub genes identified. In conclusion, these key genes and immune infiltration may be of great importance in the remission of OSA and related research of these genes may provide a new therapeutic target for OSA in the future.

Anxiogenic Potential of Experimental Sleep Fragmentation Is Duration-Dependent and Mediated via Oxidative Stress State

Sleep architecture alterations, among which sleep fragmentation is highly prevalent, represent risk factors for a variety of diseases, ranging from cardiovascular to brain disorders, including anxiety. What mediates anxiety occurrence upon sleep fragmentation is still a matter of debate. We hypothesized that the sleep fragmentation effects on anxiety are dependent on its duration and mediated by increased oxidative stress and alterations in the number of parvalbumin (PV+) interneurons in the hippocampus. Sleep was fragmented in rats by the treadmill method during a period of 14 days (SF group). Rats with undisturbed sleep in the treadmill (TC group) and those receiving equal amounts of treadmill belt motion (EC group) served as controls. To assess anxiety, we subjected rats to the open field, elevated plus maze, and light-dark tests on the 0, 7^th, and 14^th day. Upon the last test, brain structures were sampled for oxidative stress assessment and PV+ interneuron immunohistochemistry. The results of ethological tests of anxiety-linked behavior suggested duration-dependent anxiogenic potential of sleep fragmentation. Rats' anxiety-linked behavior upon sleep fragmentation significantly correlated with oxidative stress. The rats with fragmented sleep (SF) showed significantly higher oxidative stress in the hippocampus, thalamus, and cortex, compared to controls (TC and EC), while the antioxidant enzymes' activity was significantly decreased. No significant differences were observed in hippocampal PV+ interneurons among these groups. Our results showed that duration of sleep fragmentation is a significant determinant of anxiety-linked behavior, and these effects are mediated through oxidative distress in the brain. Herein, it is revealed that the sleep fragmentation-oxidative stress-anxiety axis contributes to our better understanding of pathophysiological processes, occurring due to disrupted sleep patterns.

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.

Gene co-expression analysis identifies modules related to insufficient sleep in humans

BACKGROUND

Insufficient sleep and circadian rhythm disruption may cause cancer, obesity, cardiovascular disease, and cognitive impairment. The underlying mechanisms need to be elucidated.

METHOD

Weighted gene co-expression network analysis (WGCNA) was used to identify co-expressed modules. Connectivity Map tool was used to identify candidate drugs based on top connected genes. R ptestg package was utilized to detected module rhythmicity alteration. A hypergeometric test was used to test the enrichment of insomnia SNP signals in modules. Google Scholar was used to validate the modules and hub genes by literature.

RESULTS

We identified a total of 45 co-expressed modules. These modules were stable and preserved. Eight modules were correlated with sleep restriction duration. Module rhythmicity was disrupted in sleep restriction subjects. Hub genes that involve in insufficient sleep also play important roles in sleep disorders. Insomnia GWAS signals were enriched in six modules. Finally, eight drugs associated with sleep disorders were identified.

CONCLUSION

Systems biology method was used to identify sleep-related modules, hub genes, and candidate drugs. Module rhythmicity was altered in sleep insufficient subjects. Thiamphenicol, lisuride, timolol, and piretanide are novel candidates for sleep disorders.

Intermittent Hypoxia-Induced Activation of Endothelial Cells Is Mediated via Sympathetic Activation-Dependent Catecholamine Release

Obstructive sleep apnea (OSA) is a common breathing disorder affecting a significant percentage of the adult population. OSA is an independent risk factor for cardiovascular disease (CVD); however, the underlying mechanisms are not completely understood. Since the severity of hypoxia correlates with some of the cardiovascular effects, intermittent hypoxia (IH) is thought to be one of the mechanisms by which OSA may cause CVD. Here, we investigated the effect of IH on endothelial cell (EC) activation, characterized by the expression of inflammatory genes, that is known to play an important role in the pathogenesis of CVD. Exposure of C57BL/6 mice to IH led to aortic EC activation, while in vitro exposure of ECs to IH failed to do so, suggesting that IH does not induce EC activation directly, but indirectly. One of the consequences of IH is activation of the sympathetic nervous system and catecholamine release. We found that exposure of mice to IH caused elevation of circulating levels of catecholamines. Inhibition of the IH-induced increase in catecholamines by pharmacologic inhibition or by adrenalectomy or carotid body ablation prevented the IH-induced EC activation in mice. Supporting a key role for catecholamines, epinephrine alone was sufficient to cause EC activation in vivo and in vitro. Together, these results suggested that IH does not directly induce EC activation, but does so indirectly via release of catecholamines. These results suggest that targeting IH-induced sympathetic nerve activity and catecholamine release may be a potential therapeutic target to attenuate the CV effects of OSA.

Circulating Malondialdehyde Concentrations in Obstructive Sleep Apnea (OSA): A Systematic Review and Meta-Analysis with Meta-Regression

Oxidative stress induced by nocturnal intermittent hypoxia plays a significant pathophysiological role in obstructive sleep apnea (OSA). Malondialdehyde (MDA), one of the most commonly investigated markers of lipid peroxidation, might assist with the monitoring of oxidative balance in OSA. We conducted a systematic review and meta-analysis to evaluate the differences in circulating MDA concentrations between patients with OSA and non-OSA controls. A systematic search was conducted in the electronic databases Pubmed, Web of Science, Scopus and Google Scholar from inception to December 2020 by using the following terms: “malondialdehyde” or “MDA”; and “Obstructive Sleep Apnea Syndrome”, “OSAS” or “OSA”. We identified 26 studies in 1223 OSA patients and 716 controls. The pooled MDA concentrations were significantly higher in patients with OSA (standardized mean difference (SMD) 1.43 μmol/L, 95% confidence interval (CI) 1.03 to 1.83 μmol/L, p < 0.001). There was extreme heterogeneity between the studies (I² = 92.3%, p < 0.001). In meta-regression analysis, the SMD was significantly associated with age, the assay type used and publication year. In our meta-analysis, MDA concentrations were significantly higher in OSA patients than in controls. This finding suggests that MDA, which is a marker of lipid peroxidation, is involved in the pathogenesis of OSA and provides insights for future studies investigating its potential clinical use.

Obstructive Sleep Apnea and Periodontal Disease: A Systematic Review

Background and Objectives: The objective of this study was to evaluate the association between periodontal disease and obstructive sleep apnea syndrome (OSAS). Materials and Methods: Electronic search using PubMed, Scopus, LILACS, and Cochrane library was carried out for randomized controlled trials, cohort, case-control, longitudinal and epidemiological studies on humans published from January 2009 until September 2020. The participants had to be male and female adults who were diagnosed with OSAS either by overnight polysomnography (carried out at a sleep laboratory or at home) or by a home sleep testing monitor (Apnea Risk Evaluation System). Methodological quality assessment was carried out using the Newcastle-Ottawa Quality Assessment Scale (NOS) for case-control studies while an adapted form of NOS was used for cross-sectional studies. Results: Ten studies fulfilled the inclusion criteria of our review, 5 were case-control studies, and 5 cross-sectional. Sample size ranged from 50 to 29,284 subjects, for a total of 43,122 subjects, 56% of them were male, their age ranged from 18 to 85 years old. The heterogeneity among the studies regarding the classification of periodontal disease, and the different methods for OSAS severity assessment, complicated the comparison among the studies. Conclusions: There is low evidence of a possible association between OSAS and periodontitis. The pathophysiological mechanism, cause-effect, or dose-response relationship are still unclear. Further studies are needed and should use a precise classification of OSAS subjects, while the new classification of periodontitis from the World Workshop of Chicago 2017 should be used for the periodontal assessment.

Obstructive Sleep Apnea as a Risk Factor for Intracerebral Hemorrhage

BACKGROUND AND PURPOSE

To determine whether obstructive sleep apnea (OSA) is associated with intracerebral hemorrhage (ICH) risk, we assessed premorbid OSA exposure of patients with nontraumatic ICH and matched controls.

METHODS

Ethnic/Racial Variations of Intracerebral Hemorrhage is a multicenter, case-control study evaluating risk factors for ICH that recruited 3000 cases with ICH and 3000 controls. OSA status was ascertained using the Berlin Questionnaire as a surrogate for premorbid OSA. We performed logistic regression analyses to evaluate the association between OSA and ICH.

RESULTS

Two thousand and sixty-four (71%) cases and 1516 (52%) controls were classified as having OSA by the Berlin Questionnaire. Cases with OSA were significantly more likely to be male and have hypertension, heart disease, hyperlipidemia, and higher body mass index compared with those without OSA. OSA was more common among cases compared with controls (71% versus 52%, odds ratio, 2.28 [95% CI, 2.05-2.55]). In a multivariable logistic regression model, OSA was associated with increased risk for ICH (odds ratio, 1.47 [95% CI, 1.29-1.67]).

CONCLUSIONS

OSA is a risk factor for ICH.

High Plasma Cystine Levels Are Associated with Blood Pressure and Reversed by CPAP in Patients with Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) independent of obesity (OBS) imposes severe cardiovascular risk. To what extent plasma cystine concentration (CySS), a novel pro-oxidative vascular risk factor, is increased in OSA with or without OBS is presently unknown. We therefore studied CySS together with the redox state and precursor amino acids of glutathione (GSH) in peripheral blood mononuclear cells (PBMC) in untreated male patients with OSA (apnea-hypopnea-index (AHI) > 15 h^-1, n = 28) compared to healthy male controls (n = 25) stratifying for BMI ≥ or < 30 kg m^-2. Fifteen OSA patients were reassessed after 3-5-months CPAP. CySS correlated with cumulative time at an O₂-saturation <90% (Tu90%) (r = 0.34, p < 0.05) beside BMI (r = 0.58, p < 0.001) and was higher in subjects with "hypoxic stress" (59.4 ± 2.0 vs. 50.1 ± 2.7 µM, p < 0.01) defined as Tu90% ≥ 15.2 min (corresponding to AHI ≥ 15 h^-1). Moreover, CySS significantly correlated with systolic (r = 0.32, p < 0.05) and diastolic (r = 0.31, p < 0.05) blood pressure. CPAP significantly lowered CySS along with blood pressure at unchanged BMI. Unexpectedly, GSH antioxidant capacity in PBMC was increased with OSA and reversed with CPAP. Plasma CySS levels are increased with OSA-related hypoxic stress and associated with higher blood pressure. CPAP decreases both CySS and blood pressure. The role of CySS in OSA-related vascular endpoints and their prevention by CPAP warrants further studies.

The impact of sleep disorders on microvascular complications in patients with type 2 diabetes (SLEEP T2D): the protocol of a cohort study and feasibility randomised control trial

BACKGROUND

Obstructive sleep apnoea (OSA) is very common in patients with type 2 diabetes (T2D). We and others have shown that OSA was associated with diabetes-related microvascular complications in patients with T2D in cross-sectional and longitudinal studies and that compliance with continuous positive airway pressure (CPAP) reduced the progression of microvascular complications. Hence, we hypothesised that adequate CPAP reduces the development of microvascular complication in patients with T2D.

METHODS

SLEEP T2D is a cohort study with embedded feasibility, open-label, parallel-arm, randomised control trial (RCT) over 2 years. The primary aim is the feasibility of conducting a definitive RCT assessing the impact of CPAP on chronic kidney disease and other microvascular complications in patients with T2D. The main parameters are to assess willingness of participants to be randomised, follow-up rates, CPAP adherence/compliance, to optimise the choice of outcome measures for a substantive trial, and to identify the parameters for sample size calculations. The secondary aims of the study are related to the impact of CPAP, sleep-related disorders, and sleep chronotype on a variety of diabetes-related end points. The study participants were recruited from the T2D services in multiple NHS trusts across England. The main exclusion criteria for the cohort study are as follows: T1D, eGFR < 15 mL/min/1.73 m², known OSA, active malignancy or chronic kidney disease from reasons other than diabetes, pregnancy, professional drivers, and a history of falling asleep whilst driving within last 2 years. The main exclusion criteria from the RCT were as follows: Apnoea-Hypopnoea Index < 10 and Epworth Sleepiness Score ≥ 11. Study participants were extensively phenotyped clinically and biochemically. The OSA diagnosis was based on multichannel portable device (ApneaLink Air^TM, Resmed).

DISCUSSION

The feasibility RCT will help us design the future RCT to assess the impact of CPAP on diabetes-related microvascular complications. The cohort study will generate preliminary data regarding the impact of sleep quality, duration, and chronotype on diabetes-related outcomes which could lead to further mechanistic and interventional studies.

TRIAL REGISTRATION

ISRCTN, ISRCTN12361838 . Registered 04 April 2018, Protocol version: v5.0 02.12.19.

The Association of Oxidative Stress in the Uvular Mucosa with Obstructive Sleep Apnea Syndrome: A Clinical Study

The hypothesis that individuals with obstructive sleep apnea syndrome (OSAS) demonstrate oxidative stress in the uvular mucosa that correlates with OSAS occurrence was investigated. A total of 128 participants (mean age 45.8, mean body mass index 30.7, female–male ratio 1:20) were divided into the non-OSAS group (apnea–hypopnea index—AHI < 5) and OSAS-group (AHI ≥ 5), in which mild (5 ≤ AHI < 15), moderate (15 ≤ AHI < 30), and severe (AHI ≥ 30) sub-groups were distinguished. Laryngological examination, Epworth Sleep Scale questionnaire, and home sleep study were performed to obtain AHI, mean oxygen saturation, and lowest oxygen saturation. Total oxidative status (TOS) and total antioxidative status (TAS) were assayed in the uvular mucosa taken during palatoplasty or palatopharyngoplasty. The severity of oxidative stress was expressed as oxidative stress index (OSI). Oxidative/reductive imbalance was noted in the mucosa of the uvula of OSAS individuals, and TAS of the uvular mucosa negatively correlated with the severity of this syndrome. TOS and OSI in the mild, moderate, and severe OSAS were higher than in the non-OSAS group, whereas TAS of the uvular mucosa in the OSAS group was lower compared to the non-OSAS group. In conclusion, oxidative stress in the uvular mucosa is associated with the occurrence of OSAS.

Hypoxia-inducible factors and obstructive sleep apnea

Intermittent hypoxia (IH) is a hallmark manifestation of obstructive sleep apnea (OSA), a widespread disorder of breathing. This Review focuses on the role of hypoxia-inducible factors (HIFs) in hypertension, type 2 diabetes (T2D), and cognitive decline in experimental models of IH patterned after O2 profiles seen in OSA. IH increases HIF-1α and decreases HIF-2α protein levels. Dysregulated HIFs increase reactive oxygen species (ROS) through HIF-1-dependent activation of pro-oxidant enzyme genes in addition to reduced transcription of antioxidant genes by HIF-2. ROS in turn activate chemoreflex and suppress baroreflex, thereby stimulating the sympathetic nervous system and causing hypertension. We also discuss how increased ROS generation by HIF-1 contributes to IH-induced insulin resistance and T2D as well as disrupted NMDA receptor signaling in the hippocampus, resulting in cognitive decline.

Effects of Continuous Positive Airway Pressure Treatment for Obstructive Sleep Apnea-Hypopnea Syndrome on Corneal Morphological Characteristics

PURPOSE

To evaluate the effects of continuous positive airway pressure (CPAP) therapy on corneal endothelial morphometry and pachymetry in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS).

METHODS

This prospective, observational study included patients with OSAHS who were evaluated right before and after the commencement of CPAP treatment. Each patient underwent a detailed ophthalmologic examination and assessment of their corneal endothelium with a noncontact specular microscope (Tomey EM-3000; Tomey Corp). Endothelial cell density, coefficient of variation of cell area (CV), hexagonal cell appearance ratio (%Hex), and central corneal thickness were measured. The post-CPAP results were compared with the results of a control group. The differences in the corneal parameters between pre- and post-CPAP therapy of the OSAHS group were correlated with the pretreatment polysomnography results.

RESULTS

Twenty-seven distinct eyes of 27 patients recently diagnosed with OSAHS and 30 eyes of 30 healthy individuals were used for the statistical analysis. The mean age of patients with OSAHS was 54.2 ± 11.8 years, and after 9.6 months (range 3-18 mo) of good adherence to CPAP treatment, their CV values, indicating polymegathism, decreased from 41.7 ± 8.7 to 38.3 ± 5.8 (P = 0.04), whereas %Hex, indicating pleomorphism, increased from 45.8% ± 8.2% to 48.4% ± 6.6% (P = 0.008). Their post-CPAP corneal parameters did not differ significantly from those of the control group (P > 0.05). A significant positive correlation was observed between the decrease in CV and the duration of the treatment (Rs = 0.566, P = 0.002), as well as the pre-CPAP nonrapid eye movement (NREM) sleep percentage (Rs = 0.459, P = 0.02). A negative correlation was noted between the decrease in CV and the percentage of rapid eye movement (REM) sleep (Rs = -0.459, P = 0.02).

CONCLUSIONS

Better oxygenation during sleep, resulting from increased CPAP adherence, had a significant influence on corneal endothelium, providing an improvement in corneal polymegathism and pleomorphism, with a potential return of CV and %Hex to their normal values. Greater improvement in polymegathism was observed in patients with greater proportion of NREM sleep.