Metabolic dysfunction in OSA: Is there something new under the sun?

Interplay between gut microbiota and exosome dynamics in sleep apnea

Sleep-disordered breathing (SDB) is characterized by recurrent reductions or interruptions in airflow during sleep, termed hypopneas and apneas, respectively. SDB impairs sleep quality and is linked to substantive health issues including cardiovascular and metabolic disorders, as well as cognitive decline. Recent evidence suggests a link between gut microbiota (GM) composition and sleep apnea. Indeed, GM, a community of microorganisms residing in the gut, has emerged as a potential player in various diseases, and several studies have identified associations between sleep apnea and GM diversity along with shifts in bacterial populations. Additionally, the concept of "leaky gut," a compromised intestinal barrier with potentially increased inflammation, has emerged as another key player in the potential bidirectional relationship between GM and sleep apnea. One of the potential effectors could be extracellular vesicles (EVs) underlying gut-brain communication pathways that are relevant to sleep regulation and function. Thus, therapeutic implications afforded by targeting the GM or exosomes for sleep apnea management have surfaced as promising areas of research. This review explores current understanding of the relationship between GM, exosomes and sleep apnea, highlighting key research dynamics and potential mechanisms. A comprehensive review of the literature was conducted, focusing on studies investigating GM composition, intestinal barrier function and gut-brain communication in relation to sleep apnea.

Associations of polysomnographic measures of obstructive sleep apnea, and nocturnal oxygen saturation with incident type 2 diabetes mellitus in middle-aged and older men

Obstructive sleep apnea (OSA) has been associated with incident type 2 diabetes mellitus (T2DM); however, few prospective epidemiological studies have accounted for important T2DM predictors including pre-diabetes status and testosterone. Participants in the longitudinal Men Androgens Inflammation Lifestyles Environment and Stress (MAILES) study, who underwent eight-channel home-based polysomnography (PSG) in 2010-2011 (n = 824) and were free of diabetes at baseline were included in the analysis (n = 682). From 2015 to 2021, 78.6% (n = 536) completed at least one follow-up assessment. Incident T2DM was determined by self-reported doctor diagnosis, diabetes medications, plasma glucose (fasting ≥7.0 mmol/L or random ≥11.0 mmol/L) or glycated haemoglobin ≥6.5%. Conservative hierarchical Poisson regression models adjusted associations of PSG metrics (categorical and continuous) for age, waist circumference, baseline fasting glucose and testosterone concentrations. In all, 52 men (9.7%) developed T2DM over a mean (range) of 8.3 (3.5-10.5) years. Significant age- and waist circumference-adjusted association of incident T2DM with rapid eye movement (REM) sleep apnea-hypopnea index (AHI) ≥20 events/h (incidence rate ratio [IRR] 1.5, 95% confidence interval [CI] 0.8-2.8; p = 0.23] and highest quartile of delta index (IRR 2.1, 95% CI 0.95-4.6; p = 0.066) were attenuated after adjustment for baseline glucose and testosterone, and the association with the lowest quartile of mean oxygen saturation persisted (IRR 4.2, 95% CI 1.7-10.3; p = 0.029). Categorical measures of AHI severity, oxygen desaturation index, and hypoxia burden index (HBI) were not independently associated with incident T2DM. Associations with T2DM were similar when continuous PSG variables were used; however, HBI was significant (IRR 1.015, 95% CI 1.006-1.024; p = 0.007). In a sub-sample with OSA treatment data (n = 479), these significant associations persisted after excluding adequately treated OSA (n = 32). Understanding underlying OSA endotypes generating hypoxaemia may identify opportunities for diabetes prevention.

Magnesium is a key trace element in obstructive sleep apnea: evidence from Mendelian randomization analysis and NHANES database

BACKGROUND

Obstructive sleep apnea (OSA) is a prevalent disorder posing significant health hazards. Studies have suggested an association between trace elements and OSA; however, the causal relationship of this association remains unclear.

METHODS

This study investigated the potential causal relationship between magnesium and OSA, with magnesium status evaluated through magnesium-related single nucleotide polymorphisms (SNPs) and magnesium depletion score (MDS). Mendelian Randomization (MR) and the National Health and Nutrition Examination Survey (NHANES) were used to mitigate confounders and ensure a more robust assessment.

RESULTS

MR analysis indicated a significant protective effect of magnesium against OSA (odds ratio [OR]<1, P < 0.05). A reverse MR analysis of OSA on magnesium did not show significant causal effects (P > 0.05). NHANES analysis further demonstrated a strong positive correlation between MDS and OSA, with participants scoring above 1 exhibiting a 64 % increased likelihood of developing OSA (OR = 1.64, 95 % confidence interval [CI]: 1.32-2.05, P < 0.001). Adjusted multivariable logistic regression models confirmed the robustness of this association (Model II: OR = 1.36, 95 % CI: 1.08-1.72, P = 0.018; Model III: OR = 1.30, 95 % CI: 1.03-1.63, P = 0.045). Subgroup and interaction analysis revealed no statistically significant interactions (P > 0.05).

CONCLUSION

We confirmed the causal relationship between magnesium and OSA, underscoring magnesium's role in OSA pathogenesis and suggesting that MDS may serve as a promising biomarker for identifying high-risk populations. Further studies on the biological mechanisms linking magnesium deficiency to OSA may contribute to its treatment.

Effect of chronic intermittent hypoxia on hippocampal lipid metabolism in mice: A targeted lipidomics study

Evidence suggests that cognitive impairments due to obstructive sleep apnea (OSA) are related to abnormal lipid metabolism. Abnormal lipid metabolism in the brain might be a potential cause of neurodegeneration. Nonetheless, there is limited clarity regarding the comprehensive lipid metabolism changes in the hippocampus induced by chronic intermittent hypoxia (CIH). Targeted lipidomic analysis of mouse hippocampus and HT22 cells was essential to exploring changes in lipid metabolism after CIH exposure. The approach was used to quantify 575 lipid species in mouse hippocampus and 1285 lipid species in HT22 cells, belonging to 6 different classes. Among those lipid classes, glycerophospholipids (GP), fatty acyls (FA), sphingolipids (SP), glycerolipid (GL), and prenol lipids (PR) were not significantly changed in mouse hippocampus under CIH conditions, but steroid (ST) levels were significantly reduced. Based on in vitro results, CIH exposure significantly raises the levels of several lipids, including GP, PR, SP, and ST. However, GL and FA did not change significantly. Notably, in vivo as well as in vitro experiments showed down-regulation of LPI (16:0), LPI (18:0), PC (18:1/20:4), PE (O-18:0/16:0), PE (O-16:0/22:6), PI (18:0/18:0), and up-regulation of PI (18:0/19:2). Additionally, in CIH conditions, lipid droplets (LDs) typically accumulate as a result of metabolism disorders. Disorders of lipid metabolism and the abnormal accumulation of LDs in neurons cause neuronal damage and behavioral disorders. The altered levels of LPI, PC, PE, and PI in OSA patients might provide new insights into understanding lipid metabolism disorders in the nervous system.

Circadian Biology in Obstructive Sleep Apnea-Associated Cardiovascular Disease

A dysregulated circadian system is independently associated with both Obstructive Sleep Apnea (OSA) and cardiovascular disease (CVD). OSA and CVD coexistence is often seen in patients with prolonged untreated OSA. However, the role of circadian dysregulation in their relationship is unclear. Half of the human genes, associated biological pathways, and physiological functions exhibit circadian rhythms, including blood pressure and heart rate regulation. Mechanisms related to circadian dysregulation and heart function are potentially involved in the coexistence of OSA and CVD. In this article, we provide a comprehensive overview of circadian dysregulation in OSA and associated CVD. We also discuss feasible animal models and new avenues for future research to understand their relationship. Oxygen-sensing pathways, inflammation, dysregulation of cardiovascular processes, oxidative stress, metabolic regulation, hormone signaling, and epigenetics are potential clock-regulated mechanisms connecting OSA and CVD.

Echoes in the night: How sleep quality influences auditory health

The intricate relationship between sleep disorders and hearing loss emerges as a burgeoning field of scholarly inquiry. Numerous studies have illuminated a potential correlation between the two, affecting the quality of life and overall health of individuals. Hearing loss, or auditory impairment, serves as a critical indicator of physiological dysfunction, casting a pall over the daily existence and professional endeavors of those affected, potentially leading to irreversible deafness if left untreated. Sleep disorders may cause physical and psychological changes that further affect hearing, while auditory dysfunction may detrimentally impact sleep experienced by individuals. Although certain studies have failed to find a direct link between sleep duration and hearing loss, it is evident that sleep-related issues do increase the risk of hearing loss. Thus, understanding the relationship between sleep disorders and hearing loss, alongside the underlying mechanisms, will help establish interventions aimed at enhancing sleep quality and safeguarding auditory health. This systematic review endeavors to elucidate the correlation between sleep disorders and hearing loss, offering valuable insights and guidance for future basic research and clinical applications.

Analysis of the efficacy of the ZJU index and triglyceride‒glucose product index in identifying obstructive sleep apnea hypoventilation syndrome in patients with metabolic syndrome

PURPOSE

Metabolic syndrome (MS) and obstructive sleep apnea-hypopnea syndrome (OSAHS) are associated with an increased risk of cardiometabolic disease. The coexistence of OSAHS and metabolic disorders is common, but research on how to recognize OSAHS and how OSAHS risk exacerbates metabolic disorders is limited. This study aimed to analyze the correlations of the ZJU index and triglyceride‒glucose (TyG) index with OSAHS in MS patients and to investigate the ability to use the ZJU index and TyG-related indices to assess the presence and severity of OSAHS in MS patients.

METHODS

This retrospective study included 216 MS patients with perfect polysomnographic monitoring (PSG), who were categorized into MS combined with OSAHS (n = 142) and MS alone (n = 74) groups according to the sleep monitoring results. The MS combined with OSAHS group was further categorized into mild (n = 55), moderate (n = 34), and severe (n = 53) groups according to the apnea hypopnea index (AHI). The general clinical data, clinical biochemical indices, AHI, mean oxygen saturation (MSaO2), lowest oxygen saturation (LSaO2), and longest apnea duration were collected from all the included subjects. Composite indices such as the ZJU, TyG, and TyG-BMI indices were calculated. The differences in each metabolic index among the different groups were analyzed; logistic regression analysis was used to compare the correlations between each parameter and OSAHS, and the efficacy of each parameter in identifying OSAHS in the MS population was evaluated by receiver operating characteristic (ROC) curves.

RESULTS

The ZJU, TyG, and TyG-BMI indices were associated with OSAHS after adjusting for sex, age, history of hypertension, history of diabetes, and history of smoking (all P < 0.05). The odds ratios for the ZJU, TyG, and TyG-BMI indices were 1.472 (1.293-1.674), 9.811 (3.916-24.582), and 1.032 (1.020-1.044), respectively. The ZJU, TyG, and TyG-BMI indices are effective predictors of the occurrence of OSAHS in MS patients, and their cutoff values could be used for early screening of OSAHS. The ZJU index was the strongest predictor of OSAHS, (area under the curve 0.829, 95% CI 0.771-0.888), with an optimal cutoff value of 38.940.

CONCLUSIONS

The ZJU, TyG, and TyG-BMI indices are novel, valid, and practical indicators for early screening of OSAHS risk in MS patients.

Different expression of circulating microRNA profile in tibetan OSAHS with metabolic syndrome patients

Recent empirical investigations reinforce the understanding of a profound interconnection between metabolic functions and Obstructive Sleep Apnea-hypopnea Syndrome (OSAHS). This study identifies distinctive miRNA signatures in OSAHS with Metabolic Syndrome (Mets) patients from healthy subjects, that could serve as diagnostic biomarkers or describe differential molecular mechanisms with potential therapeutic implications. In this study, OSAHS with MetS patients showed significantly higher Apnea Hyponea Index(AHI), but lower oxygen desaturation index(ODI 4/h) and minimum pulse oxygen saturation(SpO2). A total of 33 differentially expressed miRNAs by Limma method, and 31 differentially expressed miRNAs by DEseq2 method were screened. In addition, GO enrichment analysis of target genes associated with differentially expressed miRNAs revealed significant enrichment in metabolic processes, suggesting that the differential expression of OSAHS-induced miRNAs may contribute to the progression of metabolic disorders through the regulation of metabolic pathways. Furthermore, KEGG pathway enrichment analysis revealed significant enrichment in the p53 signaling pathway and several other pathways. Notably, the Wnt signaling pathway, PI3K-Akt signaling pathway, cAMP signaling pathway, and AMPK signaling pathway are implicated in the metabolic processes of glucose dysregulation and lipid homeostasis, as well as the pathogenesis of hypertension associated with OSAHS. We identified IKBKB, PIK3R1, and MAP2K1 as the target genes most associated with Mets pathogenesis in OSAHS, regulated by miR-503-5p, miR-497-5p, and miR-497-5p, respectively. Additionally, the target genes of differentially expressed miRNAs between Tibetan OSAHS patients with MetS and healthy individuals are regulated by transcription factors such as NR2C1, STAT3, STAT5a, HIF1a, ETV4, NANOG, RELA, SP1, E2F1, NFKB1, AR, and MYC. In conlusion, we found differentially expressed miRNAs in Tibetan OSAHS patients with Metabolic Syndrome for the first time. Enrichment analysis results suggest that differentially expressed miRNAs may involved in the development of OSAHS-related metabolic disorders by regulating metabolic pathways. We also revealed that IKBKB, PIK3R1, and MAP2K1 are mostly associated with metabolic disorder in OSAHS, and miR-503-5p and miR-497-5p may regulate the development of MetS associated with OSAHS by modulating IKBKB, PIK3R1, and MAP2K1.

Elastography as a non-invasive method of screening non-alcoholic fatty liver disease in the adult phenotype of paediatric obstructive sleep apnoea

PURPOSE

The high prevalence of non-alcoholic fatty liver disease (NAFLD) in obese children with obstructive sleep apnoea (OSA) calls for early non-invasive screening. The aim of this study was to use ultrasonographic liver echogenicity and elasticity to evaluate the early stages of liver injury in obese children with OSA.

METHODS

Fifty-five obese children with OSA aged 12 to 15 years were included. The control group (n = 56) consisted of healthy, non-obese children. All children underwent ultrasound examination to assess liver echogenicity using the hepatorenal index (HRI) and real-time elastography to determine the liver fibrosis index (LFI). Polysomnographic parameters, sonographic values, and clinical-biochemical assessment were statistically analysed according to OSA and its severity. Subgroup 1 was obese children with OSA and AHI < 5 and subgroup 2 was obese children with OSA and AHI ≥ 5.

RESULTS

Higher average values of HRI and LFI were recorded in the group of obese paediatric patients with OSA (mean age ± SD, 14.1 ± 2.2 year; 53% male; BMI z-score, 2.6 ± 0.35) compared to the control group (1.37 ± 0.19 vs. 1.12 ± 0.07, p < 0.001 and 1.82 ± 0.31 vs. 1.02 ± 0.27, p < 0.001). A significantly higher LFI was recorded in subgroup 2 compared to subgroup 1 (2.0 ± 0.3 vs. 1.6 ± 0.2, p < 0.001) while laboratory parameters and HRI (1.4 ± 0.2 vs. 1.4 ± 0.2, p = 0.630) did not change significantly. A strong positive correlation was found between the severity of OSA and the LFI (r = 0.454; p < 0.01).

CONCLUSIONS

These findings suggest that ultrasound elastography is a useful non-invasive screening test for OSA-related steatohepatitis in obese adolescents, but other clinical studies are needed to confirm this result.

Genetic overlap between major depressive disorder and obstructive sleep apnea

Objective

Observational studies have frequently shown a co-occurrence of psychiatric disorders and Obstructive sleep apnea (OSA), with major depressive disorder (MDD) being a prevalent psychiatric disorder. This study aims to investigate the genetic overlap between MDD and OSA to explore their underlying pathological mechanisms.

Methods

Leveraging the extensive and recent GWAS for OSA and MDD, we conducted genetic correlation analyses utilizing Linkage disequilibrium score regression (LDSC), re-evaluated their pleiotropic Single-nucleotide polymorphisms (SNP) with Cross-Phenotype Association (CPASSOC) and Colocalization (COLOC), investigated the overlap at the gene level using physical annotations and Multi-marker Analysis of GenoMic Annotation (MAGMA), and finally employed Mendelian randomization (MR) to assess potential causal relationships between the two disorders.

Results

Upon our investigation, we established that MDD and OSA exhibit high heritability (h2MDD=0.02, h2OSA=0.04) alongside a significant genetic correlation (rg=0.31, P= 1.42E-23). Utilizing CPASSOC, we identified 397 pleiotropic SNPs, associable with 45 loci, two of which share common genetic fragments with a pleiotropic role. Furthermore, the MAGMA study uncovered a total of 154 pleiotropic genes capable of influencing multiple brain regions. Lastly, leveraging MR analysis, we concluded that MDD heightens the risk of developing OSA (P=3. 10E-04, OR (95%CI):1.28(1.12~ 1.47)).

Conclusion

In summary, our study identified PCLO as a common gene between OSA and MDD and provided evidence that MDD causally contributes to the development of OSA. These insights enhance our understanding of the shared mechanisms underlying the comorbidity of these conditions.

Rest-activity rhythm disruption and metabolic health in schizophrenia: a cross-sectional actigraphy study of community-dwelling people living with schizophrenia and nonpsychiatric comparison participants

STUDY OBJECTIVES

People living with schizophrenia (PLWS) have increased physical comorbidities and premature mortality which may be linked to dysregulated rest-activity rhythms (RARs). This study aimed to compare RARs between PLWS and nonpsychiatric comparison participants (NCs) and to examine the relationships of RARs with age, sleep, metabolic, and physical health outcomes and, among PLWS, relationships of RARs with illness-related factors.

METHODS

The study sample included 26 PLWS and 36 NCs, assessed with wrist-worn actigraphy to compute RAR variables and general sleep variables. Participants completed assessments for clinical symptoms, physical health, sleep quality, medication use, and assays for fasting glycosylated hemoglobin (hemoglobin A1c) levels. We examined group differences in RAR and sleep variables, relationships of RAR variables with metabolic and physical health measures, and, among PLWS, relationships between RAR variables and illness-related measures.

RESULTS

PLWS had significantly shorter active periods, lower relative amplitude, and lower mean activity during their most active 10 hours compared to the NCs (Cohen's d = 0.79, 0.58, and 0.62, respectively). PLWS had poorer sleep quality, greater mean percent sleep, less wake after sleep onset, and higher total sleep time variability compared to NCs. PLWS had higher rates of antidepressant, anxiolytic, and antipsychotic medication use compared to NCs, which may have impacted sleep quality and objective sleep measures. Across both groups, more fragmented and variable RARs were associated with higher HbA1c levels (ηp2 = .10) and worse physical health (ηp2 = .21). Among PLWS, RARs were correlated with total sleep time (rs = .789, P < .01) and percent sleep (rs = .509, P < .05), but not with age, sleep quality, or other illness-related factors.

CONCLUSIONS

RARs provide unique information about sleep and activity for PLWS and have the potential for targeted interventions to improve metabolic health and mortality.

CITATION

Mahmood Z, Ramsey A, Kidambi N, et al. Rest-activity rhythm disruption and metabolic health in schizophrenia: a cross-sectional actigraphy study of community-dwelling people living with schizophrenia and nonpsychiatric comparison participants. J Clin Sleep Med. 2024;20(9):1505-1516.

Sleep apnoea, gut dysbiosis and cognitive dysfunction

Sleep disorders are becoming increasingly common, and their distinct effects on physical and mental health require elaborate investigation. Gut dysbiosis (GD) has been reported in sleep-related disorders, but sleep apnoea is of particular significance because of its higher prevalence and chronicity. Cumulative evidence has suggested a link between sleep apnoea and GD. This review highlights the gut-brain communication axis that is mediated via commensal microbes and various microbiota-derived metabolites (e.g. short-chain fatty acids, lipopolysaccharide and trimethyl amine N-oxide), neurotransmitters (e.g. γ-aminobutyric acid, serotonin, glutamate and dopamine), immune cells and inflammatory mediators, as well as the vagus nerve and hypothalamic-pituitary-adrenal axis. This review also discusses the pathological role underpinning GD and altered gut bacterial populations in sleep apnoea and its related comorbid conditions, particularly cognitive dysfunction. In addition, the review examines the preclinical and clinical evidence, which suggests that prebiotics and probiotics may potentially be beneficial in sleep apnoea and its comorbidities through restoration of eubiosis or gut microbial homeostasis that regulates neural, metabolic and immune responses, as well as physiological barrier integrity via the gut-brain axis.

Non-alcoholic fatty liver disease and sleep disorders

Studies have shown that non-alcoholic fatty liver disease (NAFLD) may be associated with sleep disorders. In order to explore the explicit relationship between the two, we systematically reviewed the effects of sleep disorders, especially obstructive sleep apnea (OSA), on the incidence of NAFLD, and analyzed the possible mechanisms after adjusting for confounding factors. NAFLD is independently associated with sleep disorders. Different sleep disorders may be the cause of the onset and aggravation of NAFLD. An excessive or insufficient sleep duration, poor sleep quality, insomnia, sleep-wake disorders, and OSA may increase the incidence of NAFLD. Despite that some research suggests a unidirectional causal link between the two, specifically, the onset of NAFLD is identified as a result of changes in sleep characteristics, and the reverse relationship does not hold true. Nevertheless, there is still a lack of specific research elucidating the reasons behind the higher risk of developing sleep disorders in individuals with NAFLD. Further research is needed to establish a clear relationship between NAFLD and sleep disorders. This will lay the groundwork for earlier identification of potential patients, which is crucial for earlier monitoring, diagnosis, effective prevention, and treatment of NAFLD.

Continuous positive airway pressure treatment improves bone mineral density in men affected by severe obstructive sleep apnea syndrome

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) and low bone mineral density (BMD) are 2 prevalent conditions with a significant negative impact on patients' well-being and quality of life. Recent research has shown low BMD at different bone sites in male patients with OSA. Although the efficacy of continuous positive airway pressure (CPAP) treatment for OSA has been widely demonstrated, the evidence for understanding its impact on BMD and other bone-related outcomes is insufficient. The aim of this observational study was to investigate the effect of 12 months of CPAP treatment on lumbar and femur BMD and bone-related serum biomarkers in male patients with severe OSA.

METHODS

Sixty patients (mean age: 55.1 ± 9.9 years) were consecutively included and underwent BMD measurement with dual-energy x-ray absorptiometry at baseline and after 12 months of CPAP treatment. Vitamin D, parathyroid hormone, and calcium serum levels were examined at the same time points.

RESULTS

A significant increase in BMD in the L1 (P < .001, d = 0.27) and L2 (P < .001, d = 0.26) vertebrae was observed after CPAP treatment, along with an increase in vitamin D (P < .001, d = 0.71) and calcium (P < .001, d = 0.73) levels and a decrease in parathyroid hormone levels (P < .001, d = 0.60). The increase in BMD in L1 was significantly correlated with the decrease in parathyroid hormone serum levels (r = -.50, P < .001).

CONCLUSIONS

Overall, these findings showed that beneficial OSA treatment might restore bone health and support CPAP treatment as a feasible strategy to improve BMD in male patients with severe OSA. Accordingly, diagnosing and targeting OSA may be warranted in the treatment of male patients with undetermined osteopenia and osteoporosis.

CITATION

Carpi M, Cordella A, Placidi F, et al. Continuous positive airway pressure treatment improves bone mineral density in men affected by severe obstructive sleep apnea syndrome. J Clin Sleep Med. 2024;20(1):67-73.

Association between hypoxic burden and common cardiometabolic diseases in patients with severe obstructive sleep apnea

PURPOSE

To determine the possible associations between total sleep time spent with arterial oxygen saturation < 90% (T90) and comorbid cardiometabolic diseases (CMDs) in patients with severe obstructive sleep apnea (OSA).

METHODS

A retrospective review of the chart was conducted in patients with severe OSA diagnosed by in-lab polysomnography (PSG) between January 2018 and December 2019 at Siriraj Hospital. The patients were divided into two groups: hypoxic (T90 ≥ 10%) and nonhypoxic (T90 < 10%). The association between common CMDs including hypertension (HT), type 2 diabetes mellitus (T2DM), and impaired fasting glucose (IFG) was investigated and compared between the two groups.

RESULTS

Data were collected from 450 patients with severe OSA, 289 males/161 females with a mean age of 53.5 ± 14.2 years and an apnea-hypopnea index (AHI) of 49.6 events/h. Among these, 114 patients (25.3%) were defined as the hypoxic group (T90 ≥ 10%). When compared between the hypoxic and nonhypoxic groups, the patients in the hypoxic group were significantly younger and more obese, and had a higher proportion of male patients. The majority of patients (80%) had at least one CMD; however, the most common comorbidities significantly associated with hypoxic OSA (T90 ≥ 10%) were HT and IFG.

CONCLUSION

Hypoxic burden is significantly associated with an increased prevalence of HT and IFG in patients with severe OSA. T90 may be potentially useful for predicting CMDs in these patients. However, prospective studies are still required.

On the origins of sleep disordered breathing, cardiorespiratory and metabolic dysfunction: which came first, the chicken or the egg?

Sleep disordered breathing (SDB) is a complex, sex specific and highly heterogeneous group of respiratory disorders. Nevertheless, sleep fragmentation and repeated fluctuations of arterial blood gases for several hours per night are at the core of the problem; together, they impose significant stress to the organism with deleterious consequences on physical and mental health. SDB increases the risk of obesity, diabetes, depression and anxiety disorders; however, the same health issues are risk factors for SDB. So, which came first, the chicken or the egg? What causes the appearance of the first significant apnoeic events during sleep? These are important questions because although moderate to severe SDB affects ∼500 million adults globally, we still have a poor understanding of the origins of the disease, and the main treatments (and animal models) focus on the symptoms rather than the cause. Because obesity, metabolic dysfunction and stress-related neurological disorders generally appear progressively, we discuss how the development of these diseases can lead to specific anatomical and non-anatomical traits of SDB in males and females while considering the impacts of sex steroids. In light of the growing evidence indicating that the carotid bodies are important sensors of key metabolic and endocrine signals associated with stress and dysmetabolism, we propose that these organs play a key role in the process.

Chronic intermittent hypoxia-induced cardiovascular and renal dysfunction: from adaptation to maladaptation

Chronic intermittent hypoxia (CIH) is the dominant pathological feature of human obstructive sleep apnoea (OSA), which is highly prevalent and associated with cardiovascular and renal diseases. CIH causes hypertension, centred on sympathetic nervous overactivity, which persists following removal of the CIH stimulus. Molecular mechanisms contributing to CIH-induced hypertension have been carefully delineated. However, there is a dearth of knowledge on the efficacy of interventions to ameliorate high blood pressure in established disease. CIH causes endothelial dysfunction, aberrant structural remodelling of vessels and accelerates atherosclerotic processes. Pro-inflammatory and pro-oxidant pathways converge on disrupted nitric oxide signalling driving vascular dysfunction. In addition, CIH has adverse effects on the myocardium, manifesting atrial fibrillation, and cardiac remodelling progressing to contractile dysfunction. Sympatho-vagal imbalance, oxidative stress, inflammation, dysregulated HIF-1α transcriptional responses and resultant pro-apoptotic ER stress, calcium dysregulation, and mitochondrial dysfunction conspire to drive myocardial injury and failure. CIH elaborates direct and indirect effects in the kidney that initially contribute to the development of hypertension and later to chronic kidney disease. CIH-induced morphological damage of the kidney is dependent on TLR4/NF-κB/NLRP3/caspase-1 inflammasome activation and associated pyroptosis. Emerging potential therapies related to the gut-kidney axis and blockade of aryl hydrocarbon receptors (AhR) are promising. Cardiorenal outcomes in response to intermittent hypoxia present along a continuum from adaptation to maladaptation and are dependent on the intensity and duration of exposure to intermittent hypoxia. This heterogeneity of OSA is relevant to therapeutic treatment options and we argue the need for better stratification of OSA phenotypes.

The relationship between aerodynamic characteristics of the upper airway and severity of obstructive sleep apnea in adults

OBJECTIVE

To investigate the relationship between aerodynamic characteristics of the upper airway and severity of obstructive sleep apnea (OSA) in adults.

METHODS

Ninety-seven adult OSA patients underwent polysomnography and cone beam computed tomography (CBCT). The anatomical and aerodynamic characteristics were measured based on CBCT images and computational fluid dynamics modelling of the upper airway.

RESULTS

After controlling for patients' gender, age, and body mass index (BMI), the maximum velocity during inspiration (In-Vmax) led to the largest increase in the explanatory power of apnea-hypopnea index (AHI) variation. The In-Vmax was closely correlated with the minimum axial area, and their relationship was represented by an inversely proportional fitted curve.

CONCLUSIONS

The In-Vmax was the most relevant to OSA severity, and it could be used to assist in recognizing severe OSA patients and as a primary variable to evaluate treatment outcomes of OSA. The In-Vmax was closely related to the most constricted area of the upper airway.

Chronic Intermittent Hypoxia-Induced Dysmetabolism Is Associated with Hepatic Oxidative Stress, Mitochondrial Dysfunction and Inflammation

The association between obstructive sleep apnea (OSA) and metabolic disorders is well-established; however, the underlying mechanisms that elucidate this relationship remain incompletely understood. Since the liver is a major organ in the maintenance of metabolic homeostasis, we hypothesize that liver dysfunction plays a crucial role in the pathogenesis of metabolic dysfunction associated with obstructive sleep apnea (OSA). Herein, we explored the underlying mechanisms of this association within the liver. Experiments were performed in male Wistar rats fed with a control or high fat (HF) diet (60% lipid-rich) for 12 weeks. Half of the groups were exposed to chronic intermittent hypoxia (CIH) (30 hypoxic (5% O2) cycles, 8 h/day) that mimics OSA, in the last 15 days. Insulin sensitivity and glucose tolerance were assessed. Liver samples were collected for evaluation of lipid deposition, insulin signaling, glucose homeostasis, hypoxia, oxidative stress, antioxidant defenses, mitochondrial biogenesis and inflammation. Both the CIH and HF diet induced dysmetabolism, a state not aggravated in animals submitted to HF plus CIH. CIH aggravates hepatic lipid deposition in obese animals. Hypoxia-inducible factors levels were altered by these stimuli. CIH decreased the levels of oxidative phosphorylation complexes in both groups and the levels of SOD-1. The HF diet reduced mitochondrial density and hepatic antioxidant capacity. The CIH and HF diet produced alterations in cysteine-related thiols and pro-inflammatory markers. The results obtained suggest that hepatic mitochondrial dysfunction and oxidative stress, leading to inflammation, may be significant factors contributing to the development of dysmetabolism associated with OSA.

The impact of obstructive sleep apnea on nonalcoholic fatty liver disease

Obstructive sleep apnea (OSA) is characterized by episodic sleep state-dependent collapse of the upper airway, with consequent hypoxia, hypercapnia, and arousal from sleep. OSA contributes to multisystem damage; in severe cases, sudden cardiac death might occur. In addition to causing respiratory, cardiovascular and endocrine metabolic diseases, OSA is also closely associated with nonalcoholic fatty liver disease (NAFLD). As the prevalence of OSA and NAFLD increases rapidly, they significantly exert adverse effects on the health of human beings. The authors retrieved relevant documents on OSA and NAFLD from PubMed and Medline. This narrative review elaborates on the current knowledge of OSA and NAFLD, demonstrates the impact of OSA on NAFLD, and clarifies the underlying mechanisms of OSA in the progression of NAFLD. Although there is a lack of sufficient high-quality clinical studies to prove the causal or concomitant relationship between OSA and NAFLD, existing evidence has confirmed the effect of OSA on NAFLD. Elucidating the underlying mechanisms through which OSA impacts NAFLD would hold considerable importance in terms of both prevention and the identification of potential therapeutic targets for NAFLD.

Uvulopalatopharyngoplasty with and without modified thyrohyoid suspension for obstructive sleep apnea treatment: a randomized clinical trial

PURPOSE

This study aims to compare the efficacy of Uvulopalatopharyngoplasty + Tongue Base Radiofrequency (TB-RF) and Uvulopalatopharyngoplasty + modified thyrohyoid suspension techniques + TB-RF which aimed to suspend base of tongue muscles anteriorly toward thyroid cartilage.

METHODS

This randomized controlled trial study was conducted on 48 cases of confirmed OSA between Jan, 2019 and Aug, 2022. We divided patients into two groups. One group underwent Uvulopalatopharyngoplasty + modified thyrohyoid suspension + TB-RF technique, and another one underwent Uvulopalatopharyngoplasty + TB-RF. Then, Apnea-Hypopnea Index (AHI), mean and lowest O2 saturation, Drug-Induced Sleep Endoscopy (DISE), Epworth Sleepiness Scale (ESS), Digit Symbol Substitution Test (DSST), Stanford Subjective Snoring Scale (SSSS), and T90 indexes were evaluated before and after each surgery.

RESULTS

The mean ± SD age was 39.4 ± 11.17 years. Of the 48 patients, 79.1% (n = 33) were male and 20.9% (n = 15) were female. AHI and SSSS in the Uvulopalatopharyngoplasty + modified thyrohyoid suspension group were significantly better than Uvulopalatopharyngoplasty group (P-value; 0.010). Though, there was no significant difference in terms of mean saturation, lowest desaturation, ESS, DSST, and T90 scores. The success rate in the Uvulopalatopharyngoplasty + modified thyrohyoid suspension and Uvulopalatopharyngoplasty groups, according to the Sher criteria: a minimum of 50% reduction with a final AHI less than 20, were 75% (18/24) and 41.7% (10/24), respectively. It was significantly higher in the Uvulopalatopharyngoplasty + modified thyrohyoid suspension group (P-value: 0.021).

CONCLUSION

The addition of modified thyrohyoid suspension technique to Uvulopalatopharyngoplasty have better surgical outcomes and more success rate than Uvulopalatopharyngoplasty in OSA patients.

TRIAL REGISTRATION

IRCT: IRCT20190602043791N2. https://en.irct.ir/trial/53365 .

The effect of obstructive sleep apnea on fatty liver disease may be obscured by alcohol consumption: An ordinal logistic regression analysis

BACKGROUND

Obstructive sleep apnea (OSA) is closely associated with non-alcoholic fatty liver disease (NAFLD). The current definition of NAFLD cannot exclude the involvement of alcohol consumption in the development of fatty liver disease (FLD), but alcohol can aggravate OSA and participate in steatosis. There is limited evidence on the relationship between OSA and alcohol and its effect on FLD severity.

OBJECTIVE

To determine the effect of OSA on FLD severity based on ordinal responses, and its relationship with alcohol consumption, in order to develop strategies for the prevention and treatment of FLD.

METHODS

Patients with chief complaints of "snoring" who underwent polysomnography and abdominal ultrasound between January 2015 and October 2022 were selected. A total of 325 cases were divided into three groups according to abdominal ultrasound results: no FLD (n = 66), mild FLD (n = 116), and moderately severe FLD (n = 143) group. Patients were also categorized into alcoholic and nonalcoholic groups. Univariate analysis was used to examine the correlation between OSA and FLD severity. Multivariate ordinal logistic regression analysis was further used to identify the determinants of FLD severity and differences between the alcoholic and nonalcoholic groups.

RESULTS

A higher proportion of moderately severe FLD was observed in the group with an apnea/hypopnea index (AHI) > 30 compared to the AHI<15 group in all participants and in the nonalcoholic population (all p < 0.05). There was no significant difference among these groups in the alcoholic population. Ordinal logistic regression analysis found that in all participants, age [OR = 0.966(0.947-0.986)], BMI [OR = 1.293 (1.205-1.394)], diabetes mellitus [OR = 1.932(1.132-3.343)], hyperlipidemia [OR = 2.432(1.355-4.464)], severe OSA [OR = 2.36(1.315-4.259)] (all p < 0.05) were the independent risk factors for more severe FLD. However, different risk factors applied according to alcohol consumption. In addition to age and BMI, the independent risk factors for the alcoholic group also included diabetes mellitus [OR = 3.323(1.494-7.834)] while in the non-alcoholic group risk factors included hyperlipidemia [OR = 4.094(1.639-11.137)], and severe OSA[OR = 2.956(1.334-6.664)] (all p < 0.05).

CONCLUSION

Severe OSA is an independent determinant for developing more severe NAFLD in nonalcoholic population, and alcohol consumption may obscure the effect of OSA on the progression of FLD.

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.

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

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

Obstructive Sleep Apnea and Role of the Diaphragm

Obstructive sleep apnea (OSA) causes multiple local and systemic pathophysiological consequences, which lead to an increase in morbidity and mortality in patients suffering from this disorder. OSA presents with various nocturnal events of apnoeas or hypopneas and with sub-clinical airflow limitations during wakefulness. OSA involves a large percentage of the population, particularly men, but the estimate of OSA patients could be much broader than data from the literature. Most of the research carried out in the muscle field is to understand the causes of the presence of chronic nocturnal desaturation and focus on the genioglossus muscle and other muscles related to dilating the upper airways. Sparse research has been published regarding the diaphragm muscle, which is the main muscle structure to insufflate air into the airways. The article reviews the functional anatomy of the muscles used to open the upper respiratory tract and the non-physiological adaptation that follows in the presence of OSA, as well as the functional anatomy and pathological adaptive aspects of the diaphragm muscle. The intent of the text is to highlight the disparity of clinical interest between the dilator muscles and the diaphragm, trying to stimulate a broader approach to patient evaluation.

Metabolic syndrome following a first episode of psychosis: results of a 1-year longitudinal study conducted in metropolitan Lisbon, Portugal

Objective

We aimed to assess the prevalence and course of metabolic syndrome (MetS) and the associated metabolic parameters during the year following a first episode pf psychosis (FEP).

Methods

We performed a 1-year longitudinal observation of 60 patients who experienced FEP. MetS was defined using the modified definition of the National Cholesterol Education Program Adult Treatment Panel III. We assessed the metabolic parameters and socio-demographic and psychopathological data for the participants.

Results

The mean age of the participants was 27.1 years, and 33.3% of them were women. There was an increase in the prevalence of MetS from 6.7% to 11.7% during the year following the baseline assessment during the year following the baseline assessment (p = 0.250). There were also significant increases in the prevalences of abnormal triglyceride concentration, waist circumference, and high-density lipoprotein (HDL)-cholesterol concentration during this period. In addition, there was a considerable worsening of the metabolic profile of the participants. No baseline parameters were identified to be predictors of MetS over the 1-year follow-up period.

Conclusions

We can conclude that metabolic abnormalities are common in patients with FEP and that these rapidly worsen during the first year following the diagnosis of FEP. Studies on interventions are needed to reduce metabolic risk to cardiovascular diseases following the FEP.

Sleep Disturbance Alters Cocaine-Induced Locomotor Activity: Involvement of Striatal Neuroimmune and Dopamine Signaling

Sleep disorders have high comorbidity with drug addiction and function as major risk factors for developing drug addiction. Recent studies have indicated that both sleep disturbance (SD) and abused drugs could activate microglia, and that increased neuroinflammation plays a critical role in the pathogenesis of both diseases. Whether microglia are involved in the contribution of chronic SDs to drug addiction has never been explored. In this study, we employed a mouse model of sleep fragmentation (SF) with cocaine treatment and examined their locomotor activities, as well as neuroinflammation levels and dopamine signaling in the striatum, to assess their interaction. We also included mice with, or without, SF that underwent cocaine withdrawal and challenge. Our results showed that SF significantly blunted cocaine-induced locomotor stimulation while having marginal effects on locomotor activity of mice with saline injections. Meanwhile, SF modulated the effects of cocaine on neuroimmune signaling in the striatum and in ex vivo isolated microglia. We did not observe differences in dopamine signaling in the striatum among treatment groups. In mice exposed to cocaine and later withdrawal, SF reduced locomotor sensitivity and also modulated neuroimmune and dopamine signaling in the striatum. Taken together, our results suggested that SF was capable of blunting cocaine-induced psychoactive effects through modulating neuroimmune and dopamine signaling. We hypothesize that SF could affect neuroimmune and dopamine signaling in the brain reward circuitry, which might mediate the linkage between sleep disorders and drug addiction.

“Leaky Gut” as a Keystone of the Connection between Depression and Obstructive Sleep Apnea Syndrome? A Rationale and Study Design

Obstructive sleep apnea (OSA) and depression are highly comorbid. Immune alterations, oxidative stress or microbiota dysfunction have been proposed as some mechanisms underlying this association. The aim of the proposed study is to assess the severity and profile of OSA and depressive symptoms in the context of serum microbiota metabolites, biomarkers of intestinal permeability, inflammation and oxidative stress in adult patients diagnosed with OSA syndrome. The study population consists of 200 subjects. An apnoea-hypopnoea index ≥ 5/hour is used for the diagnosis. Depressive symptoms are assessed with Beck Depression Inventory. Measured serum markers are: tumour necrosis factor–alpha and interleukin-6 for inflammation, total antioxidant capacity and malondialdehyde concentration for oxidative stress, zonulin, calprotectin, lipopolisaccharide-binding protein and intestinal fatty acids-binding protein for intestinal permeability. All of the above will be measured by enzyme-linked immunosorbent assay (ELISA). Associations between clinical symptoms profile and severity and the above markers levels will be tested. It would be valuable to seek for overlap indicators of depression and OSA to create this endophenotype possible biomarkers and form new prophylactic or therapeutic methods. The results may be useful to establish a subpopulation of patients sensitive to microbiota therapeutic interventions (probiotics, prebiotics, and microbiota transplantation).

Diurnal changes of retinal microvascular circulation and RNFL thickness measured by optical coherence tomography angiography in patients with obstructive sleep apnea-hypopnea

PURPOSE

To evaluate capillaries perfusion and retinal nerve fiber layer (RNFL) thickness diurnal changes of macular/optic disc regions among participants with or without obstructive sleep apnea-hypopnea (OSA) using spectral-domain optical coherence tomography angiography (OCTA).

METHODS

In this study, we enrolled a cohort of 35 participants including 14 patients with mild-to-moderate OSA, 12 patients with severe OSA, and 9 healthy individuals. All participants had Berlin questionnaire filled. At 20:00 and 6:30, right before and after the polysomnography examination, a comprehensive ocular examination was conducted. The systemic and ocular clinical characteristics were collected, and OCTA scans were performed repeatedly. Blood flow and RNFL thickness parameters were then exported using built-in software and analyzed accordingly.

RESULTS

After sleep, the overall vessel density (VD) variables, especially macular and choriocapillaris VDs, were relatively comparative and stable. One exception was the RPC vessel density at the inside-disc region with a decreasing trend in the mild-to-moderate group (p=0.023). RNFL changes before and after sleep in the nasal-inferior and peripapillary region were statistically significant (p=0.003; p=0.043) among three groups. And multiple testing correction verified the significant difference in diurnal changes between the mild-to-moderate group and the control group in pairwise comparisons (p=0.006; p=0.02).

CONCLUSIONS

The changes of imperceptible blood flow and RNFL thickness overnight around optic disc areas could be observed in OSA patients. Despite physiological fluctuations, aberrant diurnal changes might be useful for identifying a decrease in micro-environmental stability associated with the development of various ocular diseases such as glaucoma. Other VD variables, especially macular and choriocapillaris VDs, are relatively stable in eyes of patients having OSA with different severity.

Association between Hepatic Steatosis and Obstructive Sleep Apnea in Children and Adolescents with Obesity

BACKGROUND

Owing to the increasing rate of pediatric obesity, its complications such as non-alcoholic fatty liver disease (NAFLD) and obstructive sleep apnea (OSA) have become prevalent already in childhood. We aimed to assess the relationship between these two diseases in a cohort of children with obesity.

METHODS

We enrolled 153 children with obesity (mean age 10.5 ± 2.66, mean BMI 30.9 ± 5.1) showing OSA. Subjects underwent a laboratory evaluation, a cardio-respiratory polysomnography (PSG), and a liver ultrasound.

RESULTS

All subjects had a clinical diagnosis of OSA based on the AHI > 1/h (mean AHI 8.0 ± 5.9; range 2.21-19.0). Of these, 69 showed hepatic steatosis (62.3% as mild, 20.3% as moderate, and 17.4% as severe degree). A strong association between ALT and apnea/hypopnea index (AHI) was observed (p = 0.0003). This association was not confirmed after adjusting for hepatic steatosis (p = 0.53). By subdividing our population according to the presence/absence of steatosis, this association was found only in the steatosis group (p = 0.009). As the severity of steatosis increased, the significance of its association with AHI compared to the absence of steatosis became progressively stronger (all p < 0.0001).

CONCLUSIONS

Hepatic steatosis seems to drive the association between OSA and ALT levels, suggesting a potential pathogenic role of OSA in NAFLD.

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.