Cardiovascular morbidity in obstructive sleep apnea: oxidative stress, inflammation, and much more

Trained immunity in chronic inflammatory diseases and cancer

A decade after the term 'trained immunity' (TRIM) was coined to reflect the long-lasting hyper-responsiveness of innate immune cells with an epigenetically imprinted 'memory' of earlier stimuli, our understanding has broadened to include the potential implications of TRIM in health and disease. Here, after summarizing the well-documented beneficial effects of TRIM against infections, we discuss emerging evidence that TRIM is also a major underlying mechanism in chronic inflammation-related disorders such as periodontitis, rheumatoid arthritis and cardiovascular disease. Furthermore, mounting evidence indicates that the induction of TRIM by certain agonists confers protective antitumour responses. Although the mechanisms underlying TRIM require further study, the current knowledge enables the experimental development of innovative therapeutic approaches to stimulate or inhibit TRIM in a context-appropriate manner, such as the stimulation of TRIM in cancer or its inhibition in inflammatory disorders.

The Interplay Between Sleep Apnea and Postpartum Depression

The complicated association between sleep apnea and postpartum depression (PPD), two diseases that can have a major influence on a mother's health and well-being, is examined in this thorough review. An increasing number of people are realizing that sleep apnea, which is defined by repeated bouts of upper airway obstruction during sleep, may be a risk factor for PPD. The literature currently available on the frequency, common risk factors, and possible processes relating these two disorders is summarized in this study. We investigate the potential roles that sleep apnea-related hormone fluctuations, intermittent hypoxia, and fragmented sleep may play in the onset or aggravation of PPD. We also talk about the difficulties in identifying sleep apnea in the postpartum phase and how it can affect childcare and mother-infant attachment. The evaluation assesses the effectiveness of existing screening techniques, available treatments, and how well they manage both illnesses at the same time. Lastly, we identify research gaps and suggest future lines of inquiry to enhance maternal health outcomes.

Effect of continuous positive airway pressure therapy on blood levels of IL-6, IL-10, IL-18, IL-1β, IL-4, and IL-17 in obstructive sleep apnoea adults: A systematic review, meta-analysis and trial sequential analysis

INTRODUCTION

Obstructive sleep apnoea (OSA) is a long-term disorder characterized by frequent blockages in the upper respiratory tract during sleep, often leading to abrupt awakenings, with or without a decrease in oxygen levels. The systematic review and meta-analysis aimed to assess the effect of continuous positive airway pressure therapy (CPAP) on blood interleukin (IL) levels of IL-6, IL-10, IL-18, IL-1β, IL-4, and IL-17 in OSA adults.

MATERIALS AND METHODS

The published databases from PubMed, Scopus, Web of Science, and Cochrane Library were searched from 2003 to 2024, without any restrictions. The Review Manager software 5.3 was employed to compute effect sizes, which were presented as the standardized mean difference (SMD) along with a 95% confidence interval (CI).

RESULTS

In total, 320 records were identified through database searching; ultimately, 42 articles were included in the qualitative synthesis and then the meta-analysis. The CPAP therapy significantly reduces IL-6 levels, as indicated SMD=0.64 [95% CI: 0.35, 0.93] and P<0.0001. CPAP therapy significantly reduced IL-18 and IL-1β levels in adults with OSA, but there is no significant difference in IL-10, IL-4, or IL-17 levels. Age, blood sample, body mass index, ethnicity, and treatment duration for IL-6 and apnoea-hypopnea index with IL-10 levels were effective factors in the pooled results. Experimentally, there was an interaction between IL-18 and IL-1β.

CONCLUSIONS

CPAP therapy has a positive impact on inflammatory markers in OSA adults; remarkably, it reduces IL-6 and IL-1β levels. Nevertheless, more evidence (such as the role of ethnicity) and understanding of interactions are needed.

Back to Roots: Dysbiosis, Obesity, Metabolic Syndrome, Type 2 Diabetes Mellitus, and Obstructive Sleep Apnea-Is There an Objective Connection? A Narrative Review

In recent decades, it has become clear that the gut is more than just a digestive organ; it also functions as an immune organ with regulatory capabilities and acts as a "second brain" that influences brain function due to the presence and regulatory roles of the gut microbiota (GM). The GM is a crucial component of its host and significantly impacts human health. Dysbiosis, or microbial imbalance, has been closely linked to various diseases, including gastrointestinal, neurological, psychiatric, and metabolic disorders. The aim of this narrative review is to highlight the roles of the GM in maintaining metabolic health. Sleep is a vital biological necessity, with living organisms having evolved an internal sleep-wake rhythm that aligns with a roughly 24 h light/dark cycle, and this is known as the circadian rhythm. This cycle is essential for tissue repair, restoration, and overall optimal body functioning. Sleep irregularities have become more prevalent in modern society, with fast-paced lifestyles often disrupting normal sleep patterns. Urban living factors, such as fast food consumption, shift work, exposure to artificial light and nighttime noise, medications, and social activities, can adversely affect circadian rhythms, with dysbiosis being one of the many factors incriminated in the etiology of sleep disorders.

The association between oxidative balance score and sleep duration: a mediation analysis of a cross-sectional study

Study objectives

The Oxidative Balance Score (OBS), which reflects overall oxidation through diet and lifestyle, has been linked to sleep, but few studies have clarified this relationship. We investigated the association between OBS and sleep duration, and whether oxidative stress (OS) and inflammation mediate the underlying mechanisms.

Methods

Data were obtained from the National Health and Nutrition Examination Survey spanning the years 2007 to 2018. Multivariable logistic regression analyses were used to evaluate the association between OBS and the risk of sleep duration. Mediation analyses were conducted to investigate the role of OS and inflammatory markers.

Results

A significant negative association was found between OBS and sleep duration (p < 0.01). Meanwhile, compared to participants in OBS tertile 1, the ORs (95% CIs) of incident short sleep duration were 0.78 (0.72-0.86) and 0.72 (0.67-0.79) (both p < 0.01) for OBS tertile 2 and 3, respectively. And the ORs (95% CIs) of incident long sleep duration were 0.83 (0.73, 0.95) and 0.66 (0.57, 0.75) (both p < 0.01) for OBS tertiles 2 and 3 after adjustment for multivariate variables. A linear relationship between OBS and short/long sleep duration (p for non-linearity = 0.69/0.94, both p < 0.01) were revealed. Mediation analysis showed absolute neutrophil count, serum total bilirubin mediated the association between OBS and short/long sleep duration with 5.72, 13.41% proportion of mediation, respectively (both p < 0.001).

Conclusion

OBS is negatively associated with sleep duration. OS and inflammatory biomarkers mediate the relationship.

Epigenetics and aging: relevance for sleep medicine

PURPOSE OF REVIEW

Sleep disorders encompass a wide range of conditions with substantial individual variability. Epigenetics, the study of heritable changes beyond DNA sequence, offers a promising avenue for personalized medicine in this field.

RECENT FINDINGS

There is great potential of epigenetic markers for sleep disorder diagnosis and the development of epigenetic drugs for targeted treatment. Epigenetic age acceleration, a marker of biological aging, is linked to sleep disorders and comorbidities. Very importantly, this acceleration may be reversible with effective treatment.

SUMMARY

While the underlying mechanisms and assessment of clinical utility require further investigation, the potential of epigenetics in sleep medicine is recognized. Future research focused on closing knowledge gaps and clinical validation is crucial to translate these findings into practical applications, paving the way for more effective and personalized management of sleep disorders.

Insights into the Overlap of Chronic Obstructive Pulmonary Disease and Sleep Apnea: Experience from the Clinic of Pneumology, Târgu Mureș

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) has a severe impact on patients' health and can lead to multiple complications.

MATERIAL AND METHODS

We analyzed the co-occurrence of obstructive sleep apnea (OSA) in COPD patients hospitalized in the Pneumology Clinic of Târgu Mureș, Romania.

RESULTS

A total of 150 COPD patients were investigated by clinical examination, STOP-BANG and Epworth questionnaires, ventilatory polygraphy (PG), EKG, cardiac ultrasound, blood lipids, and sugar. Sixty-eight patients (45.3%) had OSA associated with COPD. A total of 61.7% were COPD gr. E, and 30.8% were gr. B. Frequently shown symptoms were snoring and nonrestorative sleep (100%), somnolence (73.5%), nocturnal awakenings (41.17%), morning headache (32.3%), and aggravated dyspnea. Types of OSA included obstructive (97.05%), central (2.5%), and associated obesity-hypoventilation (39.7%). A total of 76.4% were recently diagnosed with OSA. Men predominated at 70.5%, 76.4% were smokers, and 61.7% had experienced alcohol abuse. A total of 25% were overweight, and 71% had obesity. A total of 13.2% belonged to the category of 38-50-year-olds, 55.8% were in the 51-65-year-old category, 17.6% were in the 66-70-year-old category, and roughly 13.2% were in the 71-year-old category. Overlap syndrome (OS) comorbidities and complications were frequently present: 41% experienced respiratory failure, 66.1% experienced blood hypertension, 58.8% experienced ischemic cardiac disease, 32.35% experienced diabetes mellitus, 50% experienced dyslipidemia, and 29.4% experienced cor pulmonale.

CONCLUSIONS

OS conferred gravity or directly contributed to cardiovascular, respiratory, and metabolic complications. OS was associated with more severe COPD and obesity. The prevalence of smoking in OS patients was higher than the national/European average.

mTOR in the Development of Hypoxic Pulmonary Hypertension Associated with Cardiometabolic Risk Factors

The pathophysiology of pulmonary hypertension is complex and multifactorial. It is a disease characterized by increased pulmonary vascular resistance at the level due to sustained vasoconstriction and remodeling of the pulmonary arteries, which triggers an increase in the mean pulmonary artery pressure and subsequent right ventricular hypertrophy, which in some cases can cause right heart failure. Hypoxic pulmonary hypertension (HPH) is currently classified into Group 3 of the five different groups of pulmonary hypertensions, which are determined according to the cause of the disease. HPH mainly develops as a product of lung diseases, among the most prevalent causes of obstructive sleep apnea (OSA), chronic obstructive pulmonary disease (COPD), or hypobaric hypoxia due to exposure to high altitudes. Additionally, cardiometabolic risk factors converge on molecular mechanisms involving overactivation of the mammalian target of rapamycin (mTOR), which correspond to a central axis in the development of HPH. The aim of this review is to summarize the role of mTOR in the development of HPH associated with metabolic risk factors and its therapeutic alternatives, which will be discussed in this review.

The Analysis of Neutrophil to Lymphocyte Ratio (NLR), Lymphocyte to Monocyte Ratio (LMR), and Platelet to Lymphocyte Ratio (PLR) in Patients with Adenoidectomy and Tonsillectomy

Background/Objectives: Adenoidectomy and tonsillectomy are among the most commonly performed procedures in ENT practice. The neutrophil-to-lymphocyte ratio (NLR), lymphocyte-to-monocyte ratio (LMR), and platelet-to-lymphocyte ratio (PLR) are recognized inflammatory markers. This study aims to evaluate the changes in NLR, PLR, and LMR in patients undergoing adenoidectomy and tonsillectomy. Methods: The study group consisted of 980 patients who underwent adenoidectomy and/or tonsillectomy. Preoperative and postoperative inflammatory markers were measured in all patients. The NLR, LMR, and PLR values were then calculated and analyzed. Results: In patients undergoing adenoidectomy and/or tonsillectomy, the postoperative NLR was significantly lower than the preoperative NLR. Similarly, the postoperative LMR was significantly higher, and the postoperative PLR was significantly lower compared to their preoperative values. Conclusions: The significant changes in NLR, LMR, and PLR following adenoidectomy and/or tonsillectomy suggest a reduction in systemic inflammation post-surgery. These findings indicate that these procedures may contribute to the improvement of inflammatory status in patients, highlighting the potential role of these markers in monitoring surgical outcomes.

TRPC5-mediated NLRP3 inflammasome activation contributes to myocardial cell pyroptosis in chronic intermittent hypoxia rats

BACKGROUND

Chronic intermittent hypoxia (CIH) is the primary cause of myocardial inflammation in obstructive sleep apnea-hypopnea syndrome (OSAHS). Pyroptosis is a newly discovered form of programmed cell death accompanying inflammatory reactions. Our previous study showed that TRPC5 is upregulated in the myocardial injury of CIH rats. The present study aimed to explore the role of TRPC5 in CIH-induced myocardial cell pyroptosis.

METHODS

A model of CIH in OSA rats was established. SD rats were randomly divided into control group(8rats) and OSA group(8rats). Scanning electron microscope(SEM) was performed on left ventricular tissues slides. Western blot were used to detect the expression levels of pyroptosis-related factors and TRPC5 and its downstream proteins in myocardia tissue.

RESULTS

The pyroptosis of myocardial cells by SEM revealed damaged cell membrane integrity of OSA group rats, with fibrous tissue attached to the cell membrane surface, and vesicular protrusions and pyroptotic bodies were observed. Compared to the control group, the expression of pyroptosis-related proteins, such as caspase1, pro-IL-1β, IL-1β, IL-18, GSDMD, and GSDMD-N was upregulated in the OSA group (p < 0.05). Compared to the control group, the expression of TRPC5, NLPR3, p-CaMKIIβ + δ+γ, and HDAC4 was higher in the OSA group (p < 0.05).

CONCLUSIONS

These findings indicated that the pyroptosis response increases in CIH-induced myocardial injury, and the mechanism that TRPC5 is upregulated, promoting the expression of NLRP3 and inflammasome formation through CaMKII phosphorylation and HDAC4 cytoplasmic translocation. This might be a potential target for the treatment of OSA-induced myocardial injury.

A comparison of the outcomes of tonsillectomy and expansion sphincter pharyngoplasty operations in patients with obstructive sleep apnea

OBJECTIVE

To compare the efficacy of tonsillectomy and expansion sphincter pharyngoplasty (ESP) in the surgical treatment of obstructive sleep apnea (OSA).

METHODS

OSA patients with Friedman grade III-IV tonsil hypertrophy diagnosed with polysomnography were separated into two groups according to the surgery performed, as the classic tonsillectomy group (Group 1) and the ESP group (Group 2). The primary endpoint of the study was to determine the Apnea-Hypopnea Index (AHI) value.

RESULTS

Group 1 comprised 24 patients with median preoperative AHI of 19.7 and postoperative AHI of median 11.8 (p = .0001). Group 2 comprised 29 patients with median preoperative AHI of 25.1 and postoperative AHI of median 16.3 (p = .0001). Nine (37.5%) of the 24 patients in Group 1 accepted as cure (79.1%). Eight (27.5%) of the 29 patients in Group 2 accepted as cure (72.4%).

CONCLUSION

There was no superiority of ESP over tonsillectomy in patients with lateral pharyngeal obstruction.

Sex and APOE genotype influence respiratory function under hypoxic and hypoxic-hypercapnic conditions

The apolipoprotein E (APOE) gene has been studied due to its influence on Alzheimer's disease (AD) development and work in an APOE mouse model recently demonstrated impaired respiratory motor plasticity following spinal cord injury (SCI). Individuals with AD often copresent with obstructive sleep apnea (OSA) characterized by cessations in breathing during sleep. Despite the prominence of APOE genotype and sex as factors in AD progression, little is known about the impact of these variables on respiratory control. Ventilation is tightly regulated across many systems, with respiratory rhythm formation occurring in the brainstem but modulated in response to chemoreception. Alterations within these modulatory systems may result in disruptions of appropriate respiratory control and ultimately, disease. Using mice expressing two different humanized APOE alleles, we characterized how sex and the presence of APOE3 or APOE4 influences ventilation during baseline breathing (normoxia) and during respiratory challenges. We show that sex and APOE genotype influence breathing during hypoxic challenge, which may have clinical implications in the context of AD and OSA. In addition, female mice, while responding robustly to hypoxia, were unable to recover to baseline respiratory levels, emphasizing sex differences in disordered breathing.NEW & NOTEWORTHY This study is the first to use whole body plethysmography (WBP) to measure the impact of APOE alleles on breathing under normoxia and during adverse respiratory challenges in a targeted replacement Alzheimer's model. Both sex and genotype were shown to affect breathing under normoxia, hypoxic challenge, and hypoxic-hypercapnic challenge. This work has important implications regarding the impact of genetics on respiratory control as well as applications pertaining to conditions of disordered breathing including sleep apnea and neurotrauma.

CaMKIIδ-dependent dysregulation of atrial Na+ homeostasis promotes pro-arrhythmic activity in an obstructive sleep apnea mouse model

Background

Obstructive sleep apnea (OSA) has been linked to various pathologies, including arrhythmias such as atrial fibrillation. Specific treatment options for OSA are mainly limited to symptomatic approaches. We previously showed that increased production of reactive oxygen species (ROS) stimulates late sodium current through the voltage-dependent Na+ channels via Ca2+/calmodulin-dependent protein kinase IIδ (CaMKIIδ), thereby increasing the propensity for arrhythmias. However, the impact on atrial intracellular Na+ homeostasis has never been demonstrated. Moreover, the patients often exhibit a broad range of comorbidities, making it difficult to ascertain the effects of OSA alone.

Objective

We analyzed the effects of OSA on ROS production, cytosolic Na+ level, and rate of spontaneous arrhythmia in atrial cardiomyocytes isolated from an OSA mouse model free from comorbidities.

Methods

OSA was induced in C57BL/6 wild-type and CaMKIIδ-knockout mice by polytetrafluorethylene (PTFE) injection into the tongue. After 8 weeks, their atrial cardiomyocytes were analyzed for cytosolic and mitochondrial ROS production via laser-scanning confocal microscopy. Quantifications of the cytosolic Na+ concentration and arrhythmia were performed by epifluorescence microscopy.

Results

PTFE treatment resulted in increased cytosolic and mitochondrial ROS production. Importantly, the cytosolic Na+ concentration was dramatically increased at various stimulation frequencies in the PTFE-treated mice, while the CaMKIIδ-knockout mice were protected. Accordingly, the rate of spontaneous Ca2+ release events increased in the wild-type PTFE mice while being impeded in the CaMKIIδ-knockout mice.

Conclusion

Atrial Na+ concentration and propensity for spontaneous Ca2+ release events were higher in an OSA mouse model in a CaMKIIδ-dependent manner, which could have therapeutic implications.

Senolytic-facilitated Reversal of End-Organ Dysfunction in a Murine Model of Obstructive Sleep Apnea

Rationale: Obstructive sleep apnea (OSA) is a highly prevalent condition that is associated with accelerated biological aging and multiple end-organ morbidities. Current treatments, such as continuous positive airway pressure (CPAP), have shown limited cognitive, metabolic, and cardiovascular beneficial outcomes despite adherence. Thus, adjunct therapies aiming to reduce OSA burden, such as senolytics, could improve OSA outcomes.Objectives: To assess if targeting senescence in addition to partial normoxia mimicking "good" CPAP adherence can improve physiological outcomes in mice exposed to chronic intermittent hypoxia.Methods: We compared the effects of 6 weeks of therapy with either partial normoxic recovery alone or combined with the senolytic navitoclax after 16 weeks of intermittent hypoxia exposures, a hallmark of OSA, on multiphenotypic cardiometabolic and neurocognitive parameters.Measurements and Main Results: Our findings indicate that only when combined with navitoclax, partial normoxic recovery significantly improved sleepiness (sleep in the dark phase: 34% ± 4% vs. 26% ± 3%; P < 0.01), cognition (preference score: 51% ± 19% vs. 70% ± 11%; P = 0.048), coronary artery function (response to acetylcholine [vasodilation]: 56% ± 13% vs. 72% ± 10%; P < 0.001), glucose, and lipid metabolism and reduced intestinal permeability and senescence in multiple organs.Conclusions: These findings indicate that the reversibility of end-organ morbidities induced by OSA is not only contingent on restoration of normal oxygenation patterns but can be further enhanced by targeting other OSA-mediated detrimental cellular processes, such as accelerated senescence.

Identification of biomarkers and pathways for the SARS-CoV-2 infections in obstructive sleep apnea patients based on machine learning and proteomic analysis

BACKGROUND

The prevalence of obstructive sleep apnea (OSA) was found to be higher in individuals following COVID-19 infection. However, the intricate mechanisms that underscore this concomitance remain partially elucidated. The aim of this study was to delve deeper into the molecular mechanisms that underpin this comorbidity.

METHODS

We acquired gene expression profiles for COVID-19 (GSE157103) and OSA (GSE75097) from the Gene Expression Omnibus (GEO) database. Upon identifying shared feature genes between OSA and COVID-19 utilizing LASSO, Random forest and Support vector machines algorithms, we advanced to functional annotation, analysis of protein-protein interaction networks, module construction, and identification of pivotal genes. Furthermore, we established regulatory networks encompassing transcription factor (TF)-gene and TF-miRNA interactions, and searched for promising drug targets. Subsequently, the expression levels of pivotal genes were validated through proteomics data from COVID-19 cases.

RESULTS

Fourteen feature genes shared between OSA and COVID-19 were selected for further investigation. Through functional annotation, it was indicated that metabolic pathways play a role in the pathogenesis of both disorders. Subsequently, employing the cytoHubba plugin, ten hub genes were recognized, namely TP53, CCND1, MDM2, RB1, HIF1A, EP300, STAT3, CDK2, HSP90AA1, and PPARG. The finding of proteomics unveiled a substantial augmentation in the expression level of HSP90AA1 in COVID-19 patient samples, especially in severe conditions.

CONCLUSIONS

Our investigation illuminate a mutual pathogenic mechanism that underlies both OSA and COVID-19, which may provide novel perspectives for future investigations into the underlying mechanisms.

Infants hospitalized with lower respiratory tract infections during the first two years of life have increased risk of pediatric obstructive sleep apnea

RATIONALE

Lower respiratory tract infections (LRTI) during the first 2 years of life increase the risk of pediatric obstructive sleep apnea (OSA), but whether this risk varies by LRTI severity is unknown.

METHODS

We analyzed data from 2962 children, aged 0-5 years, with early-life LRTI requiring hospitalization (severe LRTI, n = 235), treated as outpatients (mild LRTI, n = 394) and without LRTI (reference group, n = 2333) enrolled in the Boston Birth Cohort. Kaplan-Meier survival estimates and Cox proportional hazards models adjusted by pertinent covariables were used to evaluate the risk of pediatric OSA.

RESULTS

Compared to children without LRTI, those with mild LRTI were at a higher risk of having OSA (hazard ratio [HR] 1.44, 95% confidence interval [CI]: 1.01-2.05), and those with severe LRTI were at the highest risk (HR 2.06, 95% CI: 1.41-3.02), independently of relevant covariables (including maternal age, race, gestational age, and type of delivery). Additional risk factors linked to a higher risk of OSA included prematurity (HR 1.34, 95% CI 1.01-1.77) and maternal obesity (HR 1.82, 95% CI 1.32-2.52). The time elapsed between LRTI and OSA diagnosis was similar in mild and severe LRTI cases, with medians of 23 and 25.5 months, respectively (p = .803).

CONCLUSION

Infants with severe early-life LRTI have a higher risk of developing OSA, and surveillance strategies to identify OSA need to be particularly focused on this group. OSA monitoring should continue throughout the preschool years as it may develop months or years after the initial LRTI hospitalization.

Bone marrow inflammatory memory in cardiometabolic disease and inflammatory comorbidities

Cardiometabolic disorders are chief causes of morbidity and mortality, with chronic inflammation playing a crucial role in their pathogenesis. The release of differentiated myeloid cells with elevated pro-inflammatory potential, as a result of maladaptively trained myelopoiesis may be a crucial factor for the perpetuation of inflammation. Several cardiovascular risk factors, including sedentary lifestyle, unhealthy diet, hypercholesterolemia, and hyperglycemia, may modulate bone marrow hematopoietic progenitors, causing sustained functional changes that favour chronic metabolic and vascular inflammation. In the present review, we summarize recent studies that support the function of long-term inflammatory memory in progenitors of the bone marrow for the development and progression of cardiometabolic disease and related inflammatory comorbidities, including periodontitis and arthritis. We also discuss how maladaptive myelopoiesis associated with the presence of mutated hematopoietic clones, as present in clonal hematopoiesis, may accelerate atherosclerosis via increased inflammation.

What happens when the lights are left on? Transcriptomic and phenotypic habituation to light pollution

Artificial light at night (ALAN) is a ubiquitous pollutant worldwide. Exposure can induce immediate behavioral and physiological changes in animals, sometimes leading to severe health consequences. Nevertheless, many organisms persist in light-polluted environments and may have mechanisms of habituating, reducing responses to repeated exposure over time, but this has yet to be tested experimentally. Here, we tested whether zebra finches (Taeniopygia guttata) can habituate to dim (0.3 lux) ALAN, measuring behavior, physiology (oxidative stress and telomere attrition), and gene expression in a repeated measures design, over 6 months. We present evidence of tolerance to chronic exposure, persistent behavioral responses lasting 8 weeks post-exposure, and attenuation of responses to re-exposure. Oxidative stress decreased under chronic ALAN. Changes in the blood transcriptome revealed unique responses to past exposure and re-exposure. Results demonstrate organismal resilience to chronic stressors and shed light on the capacity of birds to persist in an increasingly light-polluted world.

Murine Pro-Inflammatory Responses to Acute and Sustained Intermittent Hypoxia: Implications for Obstructive Sleep Apnea Research

OBJECTIVES

Obstructive sleep apnea (OSA) is characterized by chronic systemic inflammation; however, the mechanisms underlying these pathologic consequences are incompletely understood. Our objective was to determine the effects of short- versus long-term exposure to intermittent hypoxia (IH) on pro-inflammatory mediators within vulnerable organs impacted by OSA.

STUDY DESIGN

Experimental animal study.

METHODS

A total of 8-10 week old C57BL/6J mice were exposed to normoxic or IH conditions for 7 days (short-term) or 6 weeks (long-term) under 12 h light, 12 h dark cycles. After exposure, multiple tissues were collected over a 24 h period. These tissues were processed and evaluated for gene expression and protein levels of pro-inflammatory mediators from peripheral tissues.

RESULTS

We observed a global decrease in immune response pathways in the heart, lung, and liver compared with other peripheral organs after short-term exposure to IH. Although there were tissue-specific alterations in the gene expression of pro-inflammatory mediators, with down-regulation in the lung and up-regulation in the heart, we also observed reduced protein levels of pro-inflammatory mediators in the serum, lung, and heart following short-term exposure to IH. Long-term exposure to IH resulted in an overall increase in the levels of inflammatory mediators in the serum, lung, and heart.

CONCLUSIONS

We demonstrated novel, longitudinal changes in the inflammatory cascade in a mouse model of OSA. The duration of exposure to IH led to significant variability of inflammatory responses within blood and cardiopulmonary tissues. Our findings further elucidate how inflammatory responses change over the course of the disease in vulnerable organs.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:S1-S11, 2024.

Multi-dimensional sleep and mortality: The Multi-Ethnic Study of Atherosclerosis

STUDY OBJECTIVES

Multiple sleep characteristics are informative of health, sleep characteristics cluster, and sleep health can be described as a composite of positive sleep attributes. We assessed the association between a sleep score reflecting multiple sleep dimensions, and mortality. We tested the hypothesis that more favorable sleep (higher sleep scores) is associated with lower mortality.

METHODS

The Multi-Ethnic Study of Atherosclerosis (MESA) is a racially and ethnically-diverse multi-site, prospective cohort study of US adults. Sleep was measured using unattended polysomnography, 7-day wrist actigraphy, and validated questionnaires (2010-2013). 1726 participants were followed for a median of 6.9 years (Q1-Q3, 6.4-7.4 years) until death (171 deaths) or last contact. Survival models were used to estimate the association between the exposure of sleep scores and the outcome of all-cause mortality, adjusting for socio-demographics, lifestyle, and medical comorbidities; follow-up analyses examined associations between individual metrics and mortality. The exposure, a sleep score, was constructed by an empirically-based Principal Components Analysis on 13 sleep metrics, selected a priori.

RESULTS

After adjusting for multiple confounders, a 1 standard deviation (sd) higher sleep score was associated with 25% lower hazard of mortality (Hazard Ratio [HR]: 0.75; 95% Confidence interval: [0.65, 0.87]). The largest drivers of this association were: night-to-night sleep regularity, total sleep time, and the Apnea-Hypopnea Index.

CONCLUSION

More favorable sleep across multiple characteristics, operationalized by a sleep score, is associated with lower risk of death in a diverse US cohort of adults. Results suggest that interventions that address multiple dimensions may provide novel approaches for improving health.

Emerging role of metabolomics for biomarker discovery in obstructive sleep apnea

Obstructive sleep apnea (OSA) is characterized by the complete or partial blockage of the upper airway passage during sleep which causes repetitive breaks in sleep and may result in excessive daytime sleepiness. OSA has been linked to various metabolic disorders and chronic health conditions, such as obesity, diabetes, hypertension, and depression. Profiling of alterations in metabolites and their regulation in OSA has been hypothesized to be an effective approach for early diagnosis and prognosis of OSA. Several studies have characterized metabolic fingerprints associated with sleep disorders. There is a lack of understanding of metabolite contents and their alterations in OSA that may help to identify specific biomarkers. The information provided in this review will help update new methodologies and interventions of high throughput advanced molecular/metabolomics tools which may clarify the metabolic aspects and mechanisms for improved management and treatment of OSA.

Molecular Pathology, Oxidative Stress, and Biomarkers in Obstructive Sleep Apnea

Obstructive sleep apnea syndrome (OSAS) is characterized by intermittent hypoxia (IH) during sleep due to recurrent upper airway obstruction. The derived oxidative stress (OS) leads to complications that do not only concern the sleep-wake rhythm but also systemic dysfunctions. The aim of this narrative literature review is to investigate molecular alterations, diagnostic markers, and potential medical therapies for OSAS. We analyzed the literature and synthesized the evidence collected. IH increases oxygen free radicals (ROS) and reduces antioxidant capacities. OS and metabolic alterations lead OSAS patients to undergo endothelial dysfunction, osteoporosis, systemic inflammation, increased cardiovascular risk, pulmonary remodeling, and neurological alterations. We treated molecular alterations known to date as useful for understanding the pathogenetic mechanisms and for their potential application as diagnostic markers. The most promising pharmacological therapies are those based on N-acetylcysteine (NAC), Vitamin C, Leptin, Dronabinol, or Atomoxetine + Oxybutynin, but all require further experimentation. CPAP remains the approved therapy capable of reversing most of the known molecular alterations; future drugs may be useful in treating the remaining dysfunctions.

Rearrangement of cell types in the rat carotid body neurogenic niche induced by chronic intermittent hypoxia

The carotid body (CB) is a prototypical acute oxygen (O₂ )-sensing organ that mediates reflex hyperventilation and increased cardiac output in response to hypoxaemia. CB overactivation, secondary to the repeated stimulation produced by the recurrent episodes of intermittent hypoxia, is believed to contribute to the pathogenesis of sympathetic hyperactivity present in sleep apnoea patients. Although CB functional plasticity induced by chronic intermittent hypoxia (CIH) has been demonstrated, the underlying mechanisms are not fully elucidated. Here, we show that CIH induces a small increase in CB volume and rearrangement of cell types in the CB, characterized by a mobilization of immature quiescent neuroblasts, which enter a process of differentiation into mature, O₂ -sensing and neuron-like, chemoreceptor glomus cells. Prospective isolation of individual cell classes has allowed us to show that maturation of CB neuroblasts is paralleled by an upregulation in the expression of specific glomus cell genes involved in acute O₂ -sensing. CIH enhances mitochondrial responsiveness to hypoxia in maturing neuroblasts as well as in glomus cells. These data provide novel perspectives on the pathogenesis of CB-mediated sympathetic overflow that may lead to the development of new pharmacological strategies of potential applicability in sleep apnoea patients. KEY POINTS: Obstructive sleep apnoea is a frequent condition in the human population that predisposes to severe cardiovascular and metabolic alterations. Activation of the carotid body, the main arterial oxygen-sensing chemoreceptor, by repeated episodes of hypoxaemia induces exacerbation of the carotid body-mediated chemoreflex and contributes to sympathetic overflow characteristic of sleep apnoea patients. In rats, chronic intermittent hypoxaemia induces fast neurogenesis in the carotid body with rapid activation of neuroblasts, which enter a process of proliferation and maturation into O₂ -sensing chemoreceptor glomus cells. Maturing carotid body neuroblasts and glomus cells exposed to chronic intermittent hypoxia upregulate genes involved in acute O₂ sensing and enhance mitochondrial responsiveness to hypoxia. These findings provide novel perspectives on the pathogenesis of carotid body-mediated sympathetic hyperactivation. Pharmacological modulation of carotid body fast neurogenesis could help to ameliorate the deleterious effects of chronic intermittent hypoxaemia in sleep apnoea patients.

Can biomarkers predict the risk of cardiovascular disease in patients with obstructive sleep apnea syndrome?

Background/Aim: Obstructive sleep apnea syndrome (OSAS) is a clinical syndrome characterized by recurrent partial or total obstruction of the upper airway. Cardiovascular disease (CVD) is more common in OSAS patients. Biomarkers can predict the progression of OSAS disease and the occurrence of CVD. Here we investigate the effects of age, gender, body mass index (BMI), comorbidities, neutrophil-to-lymphocyte ratio (NLR), lymphocyte-to-monocyte ratio (LMR), platelet-to-lymphocyte ratio (PLR), systemic inflammatory index (SII), atherogenic index of plasma (AIP), C-reactive protein-to-albumin ratio (CAR) and monocyte to HDL cholesterol (MHR) on the severity of OSAS and the occurrence of CVD in OSAS patients. Method: This cross-sectional study included 172 OSAS patients presenting to Erzincan Binali Yildirim University Mengucek Gazi Training and Research Hospital, Sleep Service between 01.01.2021 and 31.08.2022. Polysomnography (PSG) was applied to patients participating in the study, and routine complete blood and biochemistry tests were performed. Comorbidities and demographic data of the participants were recorded. Results: The frequency of CVD, chronic pulmonary disease (CPD) and hyperlipidemia increased as the severity of OSAS increased (P=0.005, P<0.001, P=0.016, respectively). As the severity of OSAS disease increased, only the MHR indices increased (P=0.009). When OSAS groups with and without CVD were examined, OSAS patients with CVD were older and had higher BMI (P<0.001, P=0.001, respectively). In addition, tended to be females with hyperlipidemia, diabetes mellitus (DM) and high Charlson Comorbidity Index (CCI) scores (all P<0.001). When the polysomnography of OSAS patients with CVD was evaluated, apnea-hypopnea index (AHI), non-rapid eye movement (NREM)-AHI (NREM-AHI), respiratory disorder index (RDI) and oxygen desaturation index (ODI) values were higher and sleep efficiency (SE) values were lower than patients with OSAS without CVD (P=0.002, P=0.002, P=0.003, P<0.001, P<0.001, respectively). Conclusion: CVD is common in OSAS patients. As the severity of OSAS increases, the risk of developing CVD increases. Elderly female OSAS patients with hyperlipidemic, DM, high BMI, and Charlson Comorbidity Index (CCI) constitute a relatively risky group for CVD. OSAS patients with high AHI, NREM-AHI, RDI, ODI, and low SE values should be monitored more closely for CVD.

Single-cell RNA-seq uncovers cellular heterogeneity and provides a signature for paediatric sleep apnoea

BACKGROUND

Obstructive sleep apnoea (OSA) is a highly prevalent disease and a major cause of systemic inflammation leading to neurocognitive, behavioural, metabolic and cardiovascular dysfunction in children and adults. However, the impact of OSA on the heterogeneity of circulating immune cells remains to be determined.

METHODS

We applied single-cell transcriptomics analysis (scRNA-seq) to identify OSA-induced changes in transcriptional landscape in peripheral blood mononuclear cell (PBMC) composition, which uncovered severity-dependent differences in several cell lineages. Furthermore, a machine-learning approach was used to combine scRNAs-seq cell-specific markers with those differentially expressed in OSA.

RESULTS

scRNA-seq demonstrated OSA-induced heterogeneity in cellular composition and enabled the identification of previously undescribed cell types in PBMCs. We identified a molecular signature consisting of 32 genes, which distinguished OSA patients from various controls with high precision (area under the curve 0.96) and accuracy (93% positive predictive value and 95% negative predictive value) in an independent PBMC bulk RNA expression dataset.

CONCLUSION

OSA deregulates systemic immune function and displays a molecular signature that can be assessed in standard cellular RNA without the need for pre-analytical cell separation, thereby making the assay amenable to application in a molecular diagnostic setting.

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.

Carotid Body Dysfunction and Mechanisms of Disease

Emerging evidence shows that the carotid body (CB) dysfunction is implicated in various physiological and pathophysiological conditions. It has been revealed that the CB structure and neurochemical profile alter in certain human sympathetic-related and cardiometabolic diseases. Specifically, a tiny CB with a decrease of glomus cells and their dense-cored vesicles has been seen in subjects with sleep disordered breathing such as sudden infant death syndrome and obstructive sleep apnea patients and people with congenital central hypoventilation syndrome. Moreover, the CB degranulation is accompanied by significantly elevated levels of catecholamines and proinflammatory cytokines in such patients. The intermittent hypoxia stimulates the CB, eliciting augmented chemoreflex drive and enhanced cardiorespiratory and sympathetic responses. High CB excitability due to blood flow restrictions, oxidative stress, alterations in neurotransmitter gases and disruptions of local mediators is also observed in congestive heart failure conditions. On the other hand, the morpho-chemical changes in hypertension include an increase in the CB volume due to vasodilation, altered transmitter phenotype of chemoreceptor cells and elevated production of neurotrophic factors. Accordingly, in both humans and animal models CB denervation prevents the breathing instability and lowers blood pressure. Knowledge of the morphofunctional aspects of the CB, a better understanding of its role in disease and recent advances in human CB translational research would contribute to the development of new therapeutic strategies.

Racial disparity in cardiovascular morbidity and mortality associated with obstructive sleep apnea: The sleep heart health study

BACKGROUND

African Americans (AA) have higher prevalence of cardiovascular diseases (CVD) and obstructive sleep apnea (OSA) compared to Whites. Previous research demonstrated increased risk of cardiovascular complications from OSA but there is paucity of data about any interaction of race on this effect. Sleep Heart Health Study (SHHS) is a multi-center cohort study that was done to determine the cardiovascular consequences of OSA. Using this data, we assessed the racial disparity of various CVD incidence and mortality between Whites and AA associated with OSA.

METHODS

We analyzed data from 5692 participants. Logistic regressions were done to compare the incidence of all CVD and stroke between White and AA. Cumulative death risk from all causes over 13 years were assessed by Cox's proportional hazard model. All models were adjusted for age, BMI, gender, education, hypertension, diabetes, smoking, total sleep time and OSA.

RESULTS

Compared to Whites, AA had higher adjusted odds of developing any CVD (OR = 1.6, 95% CI = 1.19-2.15) and stroke (OR = 1.71, 95 CI = 1.13-2.61). OSA remains an independent risk factor for CVD (OR = 1.15, 96% CI = 1.01-1.47) and stroke (OR = 1.36, 95% CI = 1.04-2.16) after adjusting for race and other covariates. The cumulative adjusted mortality risk was 1.24 times higher in AA than White (95% CI = 1.02-1.51) during this follow up period. Subjects with OSA in highest AHI quartile had 1.35 times (95% CI = 1.13-1.63) higher mortality compared to lowest quartile.

CONCLUSION

AA race and untreated OSA are independent predictors for new onset CVD, stroke and higher all-cause mortality, after adjusting for cardiovascular risk factors.

Pregnancy outcomes in infertility patients diagnosed with sleep disordered breathing with wireless wearable sensors

OBJECTIVE

To study the feasibility of home-based assessment of sleep disordered breathing (SDB) on early pregnancy success after in vitro fertilization with novel wearable sensors.

DESIGN

Prospective observational study.

SETTING

Patients 18 to 45 years old undergoing autologous IVF at an academic infertility center.

PATIENTS

30 women (24-44 years old) INTERVENTION: Participants provided medical history, completed sleep surveys, and a single night of home sleep monitoring prior to IVF with a novel, FDA-cleared wireless sensor system (ANNE® Sleep, Sibel Health), to collect continuous measurements of heart rate, respiratory rate, pulse oxygenation, respiratory effort/snoring, peripheral arterial tonometry, pulse arrival time, and pulse transit time, an accepted surrogate of continuous blood pressure generated by pulse arrival time and pulse transit time. Sleep nights were reviewed to derive the apnea hypopnea index (AHI), defined as the average number of apnea or hypopnea events per hour. An AHI of greater than or equal to 5 events/hour was considered abnormal.

MAIN OUTCOME MEASURE

Rate of clinical pregnancy (defined as intrauterine gestational sac with a yolk sac) after IVF. Logistic regression models were used to estimate the unadjusted and adjusted odds ratio.

RESULTS

The overall rate of sleep disordered breathing of any severity was 57%. Participants with SDB had a mean AHI of 13.4 compared to 2.7 events/hr (p<0.01), were younger, and more likely to have polycystic ovary syndrome. Of the 29 patients undergoing an embryo transfer, clinical pregnancy and livebirth occurred in 35% of women with SDB compared to 58% without SDB (p = 0.22). After adjusting for age, SDB reduced pregnancy rates but was not statistically significant (aOR 0.23, 95% CI: 0.04-1.5, p = 0.12). Though polycystic ovary syndrome was associated with higher rates of SDB it was not independently associated with lower pregnancy rates.

CONCLUSION

Screening for sleep disordered breathing using home-based wireless, wearable sensors was well accepted and easily performed by infertile patients in this cohort. Sleep disordered breathing of any severity was associated with an 77% (95% CI: 0.08-1.8) lower likelihood of clinical pregnancy and live birth independent of underlying diagnosis. Future larger studies will be needed to understand the role of sleep disordered breathing and IVF outcomes.

A single-arm, open-label, multicenter, and comparative study of the ANNE sleep system vs polysomnography to diagnose obstructive sleep apnea

STUDY OBJECTIVES

Evaluate per-patient diagnostic performance of a wireless dual-sensor system (ANNE sleep) compared with reference standard polysomnography (PSG) for the diagnosis of moderate and severe obstructive sleep apnea (OSA) with a minimum prespecified threshold of 80% for both sensitivity and specificity.

METHODS

A multicenter clinical trial was conducted to evaluate ANNE sleep vs PSG to diagnose moderate and severe OSA in individuals 22 years or older. For each testing approach, apnea-hypopnea index (AHI) was manually scored and averaged by 3 registered sleep technologists blinded to the other system. Average variations > 15% were adjudicated by a sleep medicine physician.

RESULTS

In a total of n = 225 participants (mean age 53 years, range 22-88 years), PSG diagnosed 30% (n = 68) of participants with moderate or severe OSA (AHI ≥ 15 events/h) compared to 29% (n = 65) diagnosed by ANNE sleep (P = .55). The sensitivity and specificity for ANNE sleep were 90% (95% confidence interval: 80-96%) and 98% (95% confidence interval: 94-99%), respectively. Strong correlation was shown in terms of final AHI (r = .93), with an average AHI bias of 0.5 (95% limits of agreement: -12.8 to 11.8). The majority of users noted comfort with using the ANNE sleep in the home setting. No adverse events were noted.

CONCLUSIONS

Using PSG as the gold standard, ANNE sleep demonstrated high sensitivity and specificity for the diagnosis of moderate or severe OSA.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Comparative Study of the ANNE™ One System to Diagnose Obstructive Sleep Apnea; URL: https://clinicaltrials.gov/ct2/show/NCT04643782; Identifier: NCT04643782.

CITATION

Davies C, Lee JY, Walter J et al. A single-arm, open-label, multicenter, and comparative study of the ANNE sleep system vs polysomnography to diagnose obstructive sleep apnea. J Clin Sleep Med. 2022;18(12):2703-2712.

Intermittent Hypoxia Differentially Regulates Adenosine Receptors in Phrenic Motor Neurons with Spinal Cord Injury

Cervical spinal cord injury (cSCI) impairs neural drive to the respiratory muscles, causing life- threatening complications such as respiratory insufficiency and diminished airway protection. Repetitive "low dose" acute intermittent hypoxia (AIH) is a promising strategy to restore motor function in people with chronic SCI. Conversely, "high dose" chronic intermittent hypoxia (CIH; ∼8 h/night), such as experienced during sleep apnea, causes pathology. Sleep apnea, spinal ischemia, hypoxia and neuroinflammation associated with cSCI increase extracellular adenosine concentrations and activate spinal adenosine receptors which in turn constrains the functional benefits of therapeutic AIH. Adenosine 1 and 2A receptors (A1, A2A) compete to determine net cAMP signaling and likely the tAIH efficacy with chronic cSCI. Since cSCI and intermittent hypoxia may regulate adenosine receptor expression in phrenic motor neurons, we tested the hypotheses that: 1) daily AIH (28 days) downregulates A2A and upregulates A1 receptor expression; 2) CIH (28 days) upregulates A2A and downregulates A1 receptor expression; and 3) cSCI alters the impact of CIH on adenosine receptor expression. Daily AIH had no effect on either adenosine receptor in intact or injured rats. However, CIH exerted complex effects depending on injury status. Whereas CIH increased A1 receptor expression in intact (not injured) rats, it increased A2A receptor expression in spinally injured (not intact) rats. The differential impact of CIH reinforces the concept that the injured spinal cord behaves in distinct ways from intact spinal cords, and that these differences should be considered in the design of experiments and/or new treatments for chronic cSCI.

L-Citrulline Supplementation Reduces Blood Pressure and Myocardial Infarct Size under Chronic Intermittent Hypoxia, a Major Feature of Sleep Apnea Syndrome

Intermittent hypoxia (IH) is a landmark of obstructive sleep apnea (OSA) at the core of the cardiovascular consequences of OSA. IH triggers oxidative stress, a major underlying mechanism for elevated blood pressure (BP) and increased infarct size. L-citrulline is an amino acid that has been demonstrated to be protective of the cardiovascular system and exert pleiotropic effects. Therefore, we tested the impact of citrulline supplementation on IH-induced increase in BP and infarct size. Four groups of rats exposed to normoxia (N) or IH [14 days (d), 8 h/day, 30 s-O₂ 21%/30 s-O₂ 5%] and were supplemented or not with citrulline (1 g·kg^-1·d^-1). After 14 d, BP was measured, and hearts were submitted to global ischemia-reperfusion to measure infarct size. Histological and biochemical analyses were conducted on hearts and aorta to assess oxidative stress. Citrulline significantly reduced BP (-9.92%) and infarct size (-18.22%) under IH only. In the aorta, citrulline supplementation significantly decreased superoxide anion and nitrotyrosine levels under IH and abolished the IH-induced decrease in nitrite. Citrulline supplementation significantly decreased myocardial superoxide anion levels and xanthine oxidase enzyme activity under IH. Citrulline shows a cardioprotective capacity by limiting IH-induced pro-oxidant activity. Our results suggest that citrulline might represent a new pharmacological strategy in OSA patients with high cardiovascular risk.

Evaluation of auditory system in obstructive sleep apnea patients

OBJECTIVES

Obstructive sleep apnea (OSA) has been associated with auditory dysfunction both to the cochlear and higher auditory pathways. However, available literatures presented conflicting results. We aimed to study the impact of OSA severity and their polysomnography parameters on hearing function.

MATERIALS AND METHODS

A total of 44 patients were included after evaluation for sleep disorders and were divided into four groups in accordance with apnea-hypopnea index (AHI). Pure tone audiometry (PTA), distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) were compared in commensurate with the severity of AHI. Polysomnography oximetry parameters of oxygen desaturation index, mean SPO2, minimum SPO2 and percent SPO2 < 90% were correlated with their respective PTA, DPOAE and ABR results.

RESULTS

There was no significant change in the PTA, DPOAE and ABR results in connection with AHI severity. However, we found significant correlations between mean SPO2 and percent SPO2 < 90% with ABR wave I, III and V absolute latencies. Minimum SPO2 was also significantly correlated with wave III peak latency changes.

CONCLUSIONS

Mean SPO2, percent SPO2 < 90% and minimum SPO2 could be key prognostic indicators of central auditory dysfunction in OSA patients. These parameters should be explored further as indicators of OSA severity rather than utilizing AHI alone. The hypoxic burden derived could be a better predictor of auditory function abnormalities rather than one derived from AHI.

Chronic intermittent hypoxia promotes early intrahepatic endothelial impairment in rats with nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a progressive disease that ranges from simple steatosis to cirrhosis. Obstructive sleep apnea syndrome (OSAS) and chronic intermittent hypoxia (CIH) are implicated in the pathogenesis of NAFLD. However, the overlapping consequences of CIH on liver sinusoidal endothelial function over time in NAFLD are largely unknown. We explored endothelial dysfunction in a rat model of NAFLD with a high-fat diet exposed to CIH [12 h/day, every 30 s to fractional concentration of oxygen ([Formula: see text] 8%-10%]. The livers were isolated and perfused, and the endothelial function was determined by testing the vasodilation of the liver circulation to increased concentrations of acetylcholine and von Willebrand factor (vWF) and intercellular adhesion molecule 1 (ICAM-1) expression. Phosphorylated endothelial nitric oxide synthase (p-eNOS), cGMP, and oxidative stress were assessed to determine nitric oxide bioavailability. Inflammation and fibrosis were evaluated by transaminases, myeloperoxidase activity, hydroxyproline, and histological evaluation. Hypoxia-inducible factors (HIFs) were studied as a marker of hypoxia and after a second insult with acetaminophen. CIH exposure provoked typical systemic features of OSAS and provoked a decreased response in vasodilation to acetylcholine. This was associated with increased oxidative stress and reduced p-eNOS and cGMP. The microcirculation impairment due to CIH preceded significant hepatic inflammation and fibrotic changes, despite the presence of HIF expression. In conclusion, CIH exacerbates endothelial dysfunction in NAFLD rats associated with increased oxidative stress and reduced nitric oxide bioavailability. This occurs before inflammation and fibrosis establish. Our results suggest that with CIH endothelial dysfunction should be considered an early target.NEW & NOTEWORTHY We believe the findings are of relevance because we demonstrate that chronic intermittent hypoxia further augments impaired hepatic endothelial dysfunction in nonalcoholic fatty liver disease rats. Because obstructive sleep apnea syndrome is associated with systemic endothelial dysfunction in cardiovascular disorders, and chronic intermittent hypoxia is an independent and reversible risk factor for hypertension and coronary artery disease, we hypothesized that this entity may be of potential relevance in the pathophysiology of nonalcoholic fatty liver disease.

Microglia Are Necessary to Regulate Sleep after an Immune Challenge

Microglia play a critical role in the neuroimmune response, but little is known about the role of microglia in sleep following an inflammatory trigger. Nevertheless, decades of research have been predicated on the assumption that an inflammatory trigger increases sleep through microglial activation. We hypothesized that mice (n = 30) with depleted microglia using PLX5622 (PLX) would sleep less following the administration of lipopolysaccharide (LPS) to induce inflammation. Brains were collected and microglial morphology was assessed using quantitative skeletal analyses and physiological parameters were recorded using non-invasive piezoelectric cages. Mice fed PLX diet had a transient increase in sleep that dissipated by week 2. Subsequently, following a first LPS injection (0.4 mg/kg), mice with depleted microglia slept more than mice on the control diet. All mice were returned to normal rodent chow to repopulate microglia in the PLX group (10 days). Nominal differences in sleep existed during the microglia repopulation period. However, following a second LPS injection, mice with repopulated microglia slept similarly to control mice during the dark period but with longer bouts during the light period. Comparing sleep after the first LPS injection to sleep after the second LPS injection, controls exhibited temporal changes in sleep patterns but no change in cumulative minutes slept, whereas cumulative sleep in mice with repopulated microglia decreased during the dark period across all days. Repopulated microglia had a reactive morphology. We conclude that microglia are necessary to regulate sleep after an immune challenge.

Obstructive sleep apnea risk and hearing impairment among occupational noise-exposed male workers

This study aimed to investigate the association between obstructive sleep apnea (OSA) risk and hearing impairment among workers exposed to occupational noise. A cross-sectional study was conducted among 607 healthy male workers at a tire-manufacturing factory. The subjects underwent audiometric testing, and their OSA risk was examined based on the STOP-Bang questionnaire. Hearing impairment was defined as a hearing threshold >25 dB hearing level (HL) in any frequency of 1, 2, 3 and 4 kHz in either ear. High OSA risk was defined as a STOP-bang score of ≥3. Hearing thresholds at 1, 2, 3 and 4 kHz in both ears were significantly higher among workers with high OSA risk than among those with low OSA risk after adjusting for confounders. Multiple logistic regression analysis examining the association of OSA risk and STOP-Bang score with hearing impairment revealed an odds ratio of 1.738 (95% confidence interval [CI] 1.113-2.713, p = 0.015) and 1.256 (95% CI 1.031-1.529, p = 0.023), respectively, after adjusting for confounders. In addition, when the hearing impairment was reclassified into high- and low-frequency hearing impairment, a statistically significant OR was seen for high-frequency hearing impairment. In conclusion, high OSA risk was associated with hearing impairment in occupational noise-exposed workers, especially in the high-frequency range of 3 and 4 kHz. More efforts are required to improve the management of OSA and its risk factors to preserve hearing in occupational noise-exposed workers.

Effects of Intermittent Hypoxia-Hyperoxia Exposure Prior to Aerobic Cycling Exercise on Physical and Cognitive Performance in Geriatric Patients—A Randomized Controlled Trial

Background: It was recently shown that intermittent hypoxic-hyperoxic exposure (IHHE) applied prior to a multimodal training program promoted additional improvements in cognitive and physical performance in geriatric patients compared to physical training only. However, there is a gap in the literature to which extent the addition of IHHE can enhance the effects of an aerobic training. Therefore, the aim of this study was to investigate the efficacy of IHHE applied prior to aerobic cycling exercise on cognitive and physical performance in geriatric patients.

Methods: In a randomized, two-armed, controlled, and single-blinded trial, 25 geriatric patients (77–94 years) were assigned to two groups: intervention group (IG) and sham control group (CG). Both groups completed 6 weeks of aerobic training using a motorized cycle ergometer, three times a week for 20 min per day. The IG was additionally exposed to intermittent hypoxic and hyperoxic periods for 30 min prior to exercise. The CG followed the similar procedure breathing sham hypoxia and hyperoxia (i.e., normoxia). Within 1 week before and after the interventions, cognitive performance was assessed with the Dementia-Detection Test (DemTect) and the Clock Drawing Test (CDT), while physical performance was measured using the Timed “Up and Go” Test (TUG) and the Short-Physical-Performance-Battery (SPPB).

Results: No interaction effect was found with respect to the DemTect (η_p² = 0.02). An interaction effect with medium effect size (η_p² = 0.08) was found for CDT performance with a higher change over time for IG (d = 0.57) compared to CG (d = 0.05). The ANCOVA with baseline-adjustment indicated between-group differences with a large and medium effect size at post-test for the TUG (η_p² = 0.29) and SPPB (η_p² = 0.06) performance, respectively, in favour of the IG. Within-group post-hoc analysis showed that the TUG performance was worsened in the CG (d = 0.65) and remained unchanged in the IG (d = 0.19). Furthermore, SPPB performance was increased (d = 0.58) in IG, but no relevant change over time was found for CG (d = 0.00).

Conclusion: The current study suggests that an additional IHHE prior to aerobic cycling exercise seems to be more effective to increase global cognitive functions as well as physical performance and to preserve functional mobility in geriatric patients in comparison to aerobic exercise alone after a 6-week intervention period.

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.

Inflammasome Activation: A Keystone of Proinflammatory Response in Obstructive Sleep Apnea

RATIONALE

As the mechanism that links obstructive sleep apnea (OSA) with the regulation of inflammatory response is not well known, it is important to understand the inflammasome activation, mainly of nucleotide-binding oligomerization domain-like receptor 3 (NLRP3).

OBJECTIVES

To assess the NLRP3 activity in severe OSA patients and to identify its role in the systemic inflammatory response of OSA patients.

METHODS

We analyzed the NLRP3 activity as well as key components of the inflammasome cascade, such as adaptor molecule apoptosis-associated speck-like protein (ASC), caspase-1, Gasdermin D (GSDMD), interleukin (IL)-1β, IL-18 and tissue factor (TF), in monocytes and plasma from patients with severe OSA and non-apneic healthy subjects. We explored the association of the different key markers with inflammatory comorbidities.

MAIN RESULTS

Monocytes from patients with severe OSA presented higher NLRP3 activity than those from non-apneic control subjects, which directly correlated with the apnea-hypopnea index and hypoxemic indices. NLRP3 over-activity triggered inflammatory cytokines (Il-1β and IL-18) via caspase-1 and increased Gasdermin D, allowing for tissue factor to be released. In vitro models confirmed that monocytes increase NLRP3 signaling under intermittent hypoxia (IH) in an HIF-1α-dependent manner, and/or in combination with plasma from OSA patients. Plasma levels of TF were higher in OSA patients with systemic inflammatory comorbidities than in those without them.

CONCLUSIONS

In severe OSA patients, NLRP3 activation might be a linking mechanism between intermittent hypoxia and other OSA-induced immediate changes with the development of systemic inflammatory response.

Optimal application of soft-palate webbing flap pharyngoplasty combined with nasal surgery for surgical treatment of primary snoring and obstructive sleep apnea

Background

Excessive collapse of the soft palate and lateral pharyngeal wall narrowing are established causes of loud snoring and sleep apnea in subjects with obstructive sleep apnea (OSA). Therefore, delicate surgical techniques are needed to reshape the soft palate and create sufficient tension in the lateral pharyngeal wall. This study aimed to determine the therapeutic outcome and favorable indications of soft-palate webbing flap pharyngoplasty in subjects with OSA and primary snoring.

Methods

A total of 174 subjects who underwent soft-palate webbing flap pharyngoplasty combined with uvulopalatal flap and septoturbinoplasty from August 2015 to February 2020 were included in this study. Medical records, including pre- and postoperative sleep parameters, were retrospectively reviewed. The primary outcome measure was the degree of improvement in AHI after surgery. Other outcomes were differences in surgical response rates, subjective visual analog score (VAS) for snoring, sleep quality, and complications.

Results

Polysomnographic results showed that apnea–hypopnea index (AHI) scores were significantly reduced from 39.6 ± 6.1 to 22.9 ± 3.6 following soft-palate webbing flap pharyngoplasty in 59 subjects, and overall success and response rates of this technique were analyzed with 71%. We found that the successful outcomes were observed in 50% of mild (n = 12) and 56% of moderate (n = 16) subjects with OSA subjects due to lateral pharyngeal wall collapse. The success rate of soft-palate webbing flap pharyngoplasty was relatively higher in subjects with mild and moderate OSA than those with severe OSA. Additionally, the mean VAS snoring scale was 4.7 and subjects’ primary snoring intensity significantly improved to 2.9 after soft-palate webbing flap pharyngoplasty. Subjective symptoms such as daytime sleepiness and sleep quality also showed improvement. Most complications were found to be minimal and improved by 1 month after the operation.

Conclusion

Our data demonstrate that soft-palate webbing flap pharyngoplasty is an effective treatment for OSA and primary snoring and may be a promising technique to reduce lateral pharyngeal wall collapse.

A feature of maternal sleep apnea during gestation causes autism-relevant neuronal and behavioral phenotypes in offspring

Mounting epidemiologic and scientific evidence indicates that many psychiatric disorders originate from a complex interplay between genetics and early life experiences, particularly in the womb. Despite decades of research, our understanding of the precise prenatal and perinatal experiences that increase susceptibility to neurodevelopmental disorders remains incomplete. Sleep apnea (SA) is increasingly common during pregnancy and is characterized by recurrent partial or complete cessations in breathing during sleep. SA causes pathological drops in blood oxygen levels (intermittent hypoxia, IH), often hundreds of times each night. Although SA is known to cause adverse pregnancy and neonatal outcomes, the long-term consequences of maternal SA during pregnancy on brain-based behavioral outcomes and associated neuronal functioning in the offspring remain unknown. We developed a rat model of maternal SA during pregnancy by exposing dams to IH, a hallmark feature of SA, during gestational days 10 to 21 and investigated the consequences on the offspring's forebrain synaptic structure, synaptic function, and behavioral phenotypes across multiples stages of development. Our findings represent a rare example of prenatal factors causing sexually dimorphic behavioral phenotypes associated with excessive (rather than reduced) synapse numbers and implicate hyperactivity of the mammalian target of rapamycin (mTOR) pathway in contributing to the behavioral aberrations. These findings have implications for neuropsychiatric disorders typified by superfluous synapse maintenance that are believed to result, at least in part, from largely unknown insults to the maternal environment.

Association between obstructive sleep apnea and venous thromboembolism recurrence: results from a French cohort

Background

Growing evidence suggests the relationship between obstructive sleep apnea (OSA) and venous thromboembolism (VTE). Few studies focused on VTE recurrence risk associated with OSA after anticoagulation cessation.

Methods

In a prospective cohort study, patients with documented VTE, were followed for an indefinite length of time and VTE recurrence were documented and adjudicated. The primary outcome was recurrent VTE after anticoagulation discontinuation. Secondary outcomes included all-cause mortality and the clinical presentation of VTE. Univariable and multivariable analyses were performed to identify risk factors for recurrence and mortality.

Results

Among the 2109 patients with documented VTE included, 74 patients had moderate to severe OSA diagnosis confirmed by home sleep test or polysomnography. During a median follow-up of 4.8 (interquartile range 2.5–8.0) years recurrent VTE occurred in 252 patients (9 with OSA and 243 without OSA). The recurrence risk in the univariable and multivariable analysis was not increased in patients with OSA, regardless of the time of diagnosis (before or after index VTE or pooled). VTE phenotype was significantly more often PE with or without associated deep vein thrombosis in the first event and recurrence for OSA patients compared to non-OSA patients. The risk of death was not increased in the OSA population compared to non-OSA patients in multivariable analysis.

Conclusions

In patients with OSA and VTE, the risk of all-cause mortality and VTE recurrence after anticoagulation discontinuation was not increased compared to non-OSA patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12959-021-00358-8.

Maladaptive Pulmonary Vascular Responses to Chronic Sustained and Chronic Intermittent Hypoxia in Rat

Chronic sustained hypoxia (CSH), as found in individuals living at a high altitude or in patients suffering respiratory disorders, initiates physiological adaptations such as carotid body stimulation to maintain oxygen levels, but has deleterious effects such as pulmonary hypertension (PH). Obstructive sleep apnea (OSA), a respiratory disorder of increasing prevalence, is characterized by a situation of chronic intermittent hypoxia (CIH). OSA is associated with the development of systemic hypertension and cardiovascular pathologies, due to carotid body and sympathetic overactivation. There is growing evidence that CIH can also compromise the pulmonary circulation, causing pulmonary hypertension in OSA patients and animal models. The aim of this work was to compare hemodynamics, vascular contractility, and L-arginine-NO metabolism in two models of PH in rats, associated with CSH and CIH exposure. We demonstrate that whereas CSH and CIH cause several common effects such as an increased hematocrit, weight loss, and an increase in pulmonary artery pressure (PAP), compared to CIH, CSH seems to have more of an effect on the pulmonary circulation, whereas the effects of CIH are apparently more targeted on the systemic circulation. The results suggest that the endothelial dysfunction evident in pulmonary arteries with both hypoxia protocols are not due to an increase in methylated arginines in these arteries, although an increase in plasma SDMA could contribute to the apparent loss of basal NO-dependent vasodilation and, therefore, the increase in PAP that results from CIH.

Lower respiratory tract infections in early life are associated with obstructive sleep apnea diagnosis during childhood in a large birth cohort

STUDY OBJECTIVES

Several birth cohorts have defined the pivotal role of early lower respiratory tract infections (LRTI) in the inception of pediatric respiratory conditions. However, the association between early LRTI and the development of obstructive sleep apnea (OSA) in children has not been established.

METHODS

To investigate whether early LRTIs increase the risk of pediatric OSA, we analyzed clinical data in children followed during the first 5 years in the Boston Birth Cohort (n = 3114). Kaplan-Meier survival estimates and Cox proportional hazards models adjusted by pertinent covariates were used to evaluate the risk of OSA by the age of 5 years between children with LRTI during the first 2 years of life in comparison to those without LRTI during this period.

RESULTS

Early life LRTI increased the risk of pediatric OSA independently of other pertinent covariates and risk factors (hazard ratio, 1.53; 95% CI, 1.15 to 2.05). Importantly, the association between LRTI and pediatric OSA was limited to LRTIs occurring during the first 2 years of life. Complementarily to this finding, we observed that children who had severe respiratory syncytial virus bronchiolitis during infancy had two times higher odds of OSA at 5 years in comparison with children without this exposure (odds ratio, 2.09; 95% CI, 1.12 to 3.88).

CONCLUSIONS

Children with severe LRTIs in early life have significantly increased risk of developing OSA during the first 5 years of life. Our results offer a new paradigm for investigating novel mechanisms and interventions targeting the early pathogenesis of OSA in the pediatric population.

Maternal and fetal outcomes in pregnancies with obstructive sleep apnea

OBJECTIVES

Obstructive sleep apnea (OSA) is linked to many health comorbidities. We aimed to ascertain if OSA correlates with a rise in poor obstetrical outcomes.

METHODS

Employing the United States' Healthcare Cost and Utilization Project - National Inpatient Sample, we performed our retrospective cohort study including all women who delivered between 2006 and 2015. ICD-9 codes were used to characterize women as having a diagnosis of OSA. Temporal trends in pregnancies with OSA were studied, baseline features were evaluated among gravidities in the presence and absence of OSA, and multivariate logistic regression analysis was utilized in assessing consequences of OSA on patient and newborn outcomes.

RESULTS

Of a total 7,907,139 deliveries, 3,115 belonged to patients suffering from OSA, resulting in a prevalence of 39 per 100,000 deliveries. Rates rose from 10.14 to 78.12 per 100,000 deliveries during the study interval (p<0.0001). Patients diagnosed with OSA were at higher risk of having pregnancies with preeclampsia, OR 2.2 (95% CI 2.0-2.4), eclampsia, 4.1 (2.4-7.0), chorioamnionitis, 1.4 (1.2-1.8), postpartum hemorrhage, 1.4 (1.2-1.7), venous thromboembolisms, 2.7 (2.1-3.4), and to deliver by caesarean section, 2.1 (1.9-2.3). Cardiovascular and respiratory complications were also more common among these women, as was maternal death, 4.2 (2.2-8.0). Newborns of OSA patients were at elevated risk of being premature, 1.3 (1.2-1.5) and having congenital abnormalities, 2.3 (1.7-3.0).

CONCLUSIONS

Pregnancies with OSA were linked to an elevated risk of poor maternal and neonatal outcomes. During pregnancy, OSA patients should receive attentive follow-up care in a tertiary hospital.

Sleep Measurement in Children-Are We on the Right Track?

Sleep plays a critical role in the development of healthy children. Detecting sleep and sleep disorders and the effectiveness of interventions for improving sleep in children require valid sleep measures. Assessment of sleep in children, in particular infants and young children, can be a quite challenging task. Many subjective and objective methods are available to evaluate various aspects of sleep in childhood, each with their strengths and limitations. None can, however, replace the importance of thorough clinical interview with detailed history and clinical examination by a sleep specialist.