Obstructive Sleep Apnea and Inflammation: Proof of Concept Based on Two Illustrative Cytokines

Inflammatory markers in children with obstructive sleep apnea syndrome

Objective

To evaluate serum inflammatory markers of YKL-40, Interleukin-6 (IL-6), Interleukin-8(IL-8), Interleukin-10(IL-10), TNF-α(tumor necrosis factor-α), and CRP (C-reactive protein) in children with and without OSAS.

Methods

The ELISA technique has been used to identify the concentration of inflammatory markers such as YKL-40, IL-6, IL-8, IL-10, TNF-α, and CRP in the serum of 83 children with OSAS and 83 children without OSAS.

Results

Serum levels of YKL-40, IL-6, IL-8, and IL-10 were found to be increased in children with OSAS. YKL-40 was found to be positively correlated with IL-6 and IL-8, and negatively correlated with IL-10. At the same time,YKL-40 was also found to be positively correlated with OAHI and LoSpO2% in OSAS group. IL-8 was positively correlated with OAHI whereas IL-10 was positively correlated with LoSpO2.

Conclusion

Children with OSAS are in a systemic inflammatory state. YKL-40 together with IL-8 may act as serum inflammatory markers and provide an indication for the diagnosis of children with OSAS.

Impact of obstructive sleep apnea on the expression of inflammatory mediators in diabetic macular edema

PURPOSE

To determine differences in inflammatory markers expressed in diabetic macular edema (DME) patients with and without obstructive sleep apnea (OSA).

METHODS

This was a prospective, cross-sectional study. Patients with treatment naive DME were enrolled in the study. They were stratified into 2 groups based on Apnea Hypopnea Index (AHI) from overnight polysomnography: OSA + (AHI ≥ 15) and OSA - (AHI<15). Multiplex immunoassay was performed for aqueous and serum cytokines including VEGF, placental growth factor (PGF), ICAM, IL2, IL3, IL6, IL8, IL10, IL17, vascular cell adhesion molecule-1 (VCAM1), monocyte attractant protein-1 (MCP1), epidermal growth factor (EGF) and platelet derived growth factor (PDGF). Statistical significance was defined as p < 0.004 using Bonferroni correction.

RESULTS

32 DME positive patients were enrolled in the study; of which 17 patients were OSA + and 15 OSA-. The OSA + cohort had significantly higher levels of serum EGF (p = 0.003), and trended towards higher levels of most serum cytokines including ICAM and IL6. OSA- cohort had significantly higher levels of aqueous IL17 compared to the OSA + cohort (2.97 ± 1.7 vs. 1.4 ± 0.46 pg/mL, p = 0.004). There were no significant differences in other aqueous cytokines.

CONCLUSIONS

OSA + group trended towards higher levels of most serum inflammatory markers, suggesting a greater pro-inflammatory state. However, they did not have significantly greater level of aqueous cytokines.

Intermittent Hypoxia and Weight Loss: Insights into the Etiology of the Sleep Apnea Phenotype

Sleep apnea (SA) is a major respiratory disorder with increased risk for hypertension and obesity; however, our understanding of the origins of this complex disorder remains limited. Because apneas lead to recurrent drops in O₂ during sleep, intermittent hypoxia (IH) is the main animal model to explore the pathophysiology of SA. Here, we assessed the impacts of IH on metabolic function and related signals. Adult male rats were exposed to 1 week of moderate IH (FiO₂ = 0.10-30 s, ten cycles/hour, 8 h/day). Using whole-body plethysmography, we measured respiratory variability and apnea index during sleep. Blood pressure and heart rate were measured by the tail-cuff method; blood samples were taken for multiplex assay. At rest, IH augmented arterial blood pressure, respiratory instability, but not apnea index. IH induced weight, fat, and fluid loss. IH also reduced food intake and plasma leptin, adrenocorticotropic hormone (ACTH), and testosterone levels but increased inflammatory cytokines. We conclude that IH does not replicate the metabolic clinical features of SA patient, thus raising our awareness of the limitations of the IH model. The fact that the risk for hypertension occurs before the appearance of apneas provides new insights into the progression of the disease.

CD40LG and GZMB were correlated with adipose tissue macrophage infiltration and involved in obstructive sleep apnea related metabolic dysregulation: Evidence from bioinformatics analysis

Both obesity and obstructive sleep apnea (OSA) can lead to metabolic dysregulation and systemic inflammation. Similar to obesity, increasing evidence has revealed that immune infiltration in the visceral adipose tissue (VAT) is associated with obstructive sleep apnea-related morbidity. However, the pathological changes and potential molecular mechanisms in visceral adipose tissue of obstructive sleep apnea patients need to be further studied. Herein, by bioinformatics analysis and clinical validation methods, including the immune-related differentially expressed genes (IRDEGs) analysis, protein-protein interaction network (PPI), functional enrichment analysis, a devolution algorithm (CIBERSORT), spearman's correlation analysis, polymerase chain reaction (PCR), Enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry (IHC), we identified and validated 10 hub IRDEGs, the relative mRNA expression of four hub genes (CRP, CD40LG, CCL20, and GZMB), and the protein expression level of two hub genes (CD40LG and GZMB) were consistent with the bioinformatics analysis results. Immune infiltration results further revealed that obstructive sleep apnea patients contained a higher proportion of pro-inflammatory M1 macrophages and a lower proportion of M2 macrophages. Spearman's correlation analysis showed that CD40LG was positively correlated with M1 macrophages and GZMB was negatively correlated with M2 macrophages. CD40LG and GZMB might play a vital role in the visceral adipose tissue homeostasis of obstructive sleep apnea patients. Their interaction with macrophages and involved pathways not only provides new insights for understanding molecular mechanisms but also be of great significance in discovering novel small molecules or other promising candidates as immunotherapies of OSA-associated metabolic complications.

A novel OSA-related model of intermittent hypoxia in endothelial cells under flow reveals pronounced inflammatory pathway activation

Obstructive sleep apnea (OSA) is a common sleep-related breathing disorder characterized by recurrent episodes of upper airway obstruction and subsequent hypoxia. In patients with OSA, severity and number of these hypoxic events positively correlate with the extent of associated cardiovascular pathology. The molecular mechanisms underlying intermittent hypoxia (IH)-driven cardiovascular disease in OSA, however, remain poorly understood-partly due to the lack of adequate experimental models. Here, we present a novel experimental approach that utilizes primary human endothelial cells cultivated under shear stress. Oxygen partial pressure dynamics were adopted in our in vitro model according to the desaturation-reoxygenation patterns identified in polysomnographic data of severe OSA patients (n = 10, with 892 severe desaturations, SpO₂<80%). Using western blot analysis, we detected a robust activation of the two major inflammatory pathways ERK and NF-κB in endothelial cells, whereas no HIF1α and HIF2α protein stabilization was observed. In line with these findings, mRNA and protein expression of the pro-inflammatory adhesion and signaling molecule ICAM-1 and the chemokine CCL2 were significantly increased. Hence, we established a novel in vitro model for deciphering OSA-elicited effects on the vascular endothelium. First data obtained in this model point to the endothelial activation of pro-inflammatory rather than hypoxia-associated pathways in OSA. Future studies in this model might contribute to the development of targeted strategies against OSA-induced, secondary cardiovascular disease.

Obstructive Sleep Apnea, Circadian Clock Disruption, and Metabolic Consequences

Obstructive sleep apnea (OSA) is a chronic disorder characterized by recurrent episodes of apnea and hypopnea during sleep. It is associated with various cardiovascular and metabolic complications, including type 2 diabetes mellitus (T2DM) and obesity. Many pathways can be responsible for T2DM development in OSA patients, e.g., those related to HIF-1 and SIRT1 expression. Moreover, epigenetic mechanisms, such as miRNA181a or miRNA199, are postulated to play a pivotal role in this link. It has been proven that OSA increases the occurrence of circadian clock disruption, which is also a risk factor for metabolic disease development. Circadian clock disruption impairs the metabolism of glucose, lipids, and the secretion of bile acids. Therefore, OSA-induced circadian clock disruption may be a potential, complex, underlying pathway involved in developing and exacerbating metabolic diseases among OSA patients. The current paper summarizes the available information pertaining to the relationship between OSA and circadian clock disruption in the context of potential mechanisms leading to metabolic disorders.

Sleep and Neuroimmunomodulation for Maintenance of Optimum Brain Function: Role of Noradrenaline

Immune function and sleep are two normal physiological processes to protect the living organism from falling sick. There is hardly any disease in which they remain unaffected, though the quantum of effect may differ. Therefore, we propose the existence of a strong correlation between sleep (quality or quantity) and immune response. This may be supported by the fact that sleep loss modulates many of the immunological molecules, which includes interferons; however, not much is known about their mechanism of action. Sleep is divided into rapid eye movement sleep (REMS) and non-REMS. For practical reasons, experimental studies have been conducted mostly by inducing loss of REMS. It has been shown that withdrawal of noradrenaline (NA) is a necessity for generation of REMS. Moreover, NA level increases in the brain upon REMS loss and the elevated NA is responsible for many of the sleep loss-associated symptoms. In this review, we describe how sleep (and its disturbance/loss) modulates the immune system by modulating the NA level in the brain or vice versa to maintain immune functions, physiological homeostasis, and normal healthy living. The increased levels of NA during REMS loss may cause neuroinflammation possibly by glial activation (as NA is a key modulator of microglia). Therefore, maintaining sleep hygiene plays a crucial role for a normal healthy living.

Dietary Inflammatory Index and sleep quality and duration among pregnant women with overweight or obesity

STUDY OBJECTIVES

Sleep disturbances, which can worsen during pregnancy, have been linked to inflammatory processes. This study tested the hypothesis that more pro-inflammatory diets during pregnancy are associated with a decrease in sleep quality and shorter sleep duration.

METHODS

The Health in Pregnancy and Postpartum study promoted a healthy lifestyle in pregnant women with pre-pregnancy overweight or obesity (n = 207). Data from <16 weeks and 32 weeks gestation were used. Sleep was measured using BodyMedia's SenseWear® armband. Diet was assessed using two 24-hr dietary recalls. Energy-density Dietary Inflammatory Index (E-DIITM) scores were calculated from micro and macronutrients. Linear mixed-effects models estimated the impact of the E-DII score on sleep parameters.

RESULTS

Women with more pro-inflammatory diets, compared to those with more anti-inflammatory diets, were more likely to be nulliparous (51% vs. 25%, p = 0.03), frequent consumers of fast food (29% vs. 10% consuming on 4-6 days during the previous week, p = 0.01), ever-smokers (21% vs. 6%, p = 0.02), and younger (mean age 29.2 vs. 31.3 years, p = 0.02). For every one-unit increase (i.e., more pro-inflammatory) in the E-DII score, sleep latency increased by 0.69 min (p < 0.01). Among European Americans only, every one-unit higher E-DII was associated with a 2.92-min longer wake-after-sleep-onset (p = 0.02).

CONCLUSION

An E-DII score that is 5 points lower (i.e., more anti-inflammatory) would equate to about 105 min of additional sleep per week among European American women. Anti-inflammatory diets may help to counteract detriments in sleep during pregnancy, especially among European American women. Additional work is needed among African American women.

CLINICAL TRIALS IDENTIFIER

Name: Promoting Health in Pregnancy and Postpartum (HIPP); URL: https://clinicaltrials.gov/ct2/show/NCT02260518; Registration Identifier: NCT02260518.

Associations between sleep apnea risk and cardiovascular disease indicators among Chinese and Korean Americans

STUDY OBJECTIVES

While sleep apnea has been associated with cardiovascular disease (CVD) risk factors in white individuals in the U.S., these associations in Chinese and Korean Americans are less well-understood, particularly how these associations vary by age, gender, Asian origin, obesity, chronic conditions, and daytime sleepiness.

METHODS

We used a sample of Chinese and Korean Americans ages 50-75 (n = 394) from the Baltimore-Washington DC Metropolitan Area to examine the associations of high risk (HR) sleep apnea with diagnoseable hypercholesterolemia and diabetes, as well as the following biomarkers: total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), total cholesterol/HDL-C ratio, triglycerides, and glucose (non-fasting). Poisson models included demographic factors, socioeconomic status, and body mass index (BMI). We tested for potential effect modifiers.

RESULTS

HR-sleep apnea was associated with higher LDL-C level (β = 14.56, p < 0.05) and higher total cholesterol/HDL ratio (β = 0.64, p < 0.01). Younger respondents had higher levels of triglycerides associated with HR-sleep apnea than older respondents. For men, HR-sleep apnea was associated with higher total cholesterol, total cholesterol/HDL-C ratio, and triglycerides. Obese and overweight respondents had positive associations between HR-sleep apnea and total cholesterol, total cholesterol/HDL ratio, and triglycerides, while underweight/normal weight individuals did not. The interactions between snoring and daytime sleepiness were associated with hypercholesterolemia and diabetes.

CONCLUSIONS

This study demonstrates associations between sleep apnea risk and dyslipidemia among Chinese and Korean Americans. Associations were particularly pronounced among younger, male, overweight/obese, and sicker individuals. Future research should examine how to improve sleep health in Asian American populations to improve CVD risk.

Reduced sleep duration increases the risk of lower urinary tract symptoms suggestive of benign prostatic hyperplasia in middle-aged and elderly males: a national cross-sectional study

BACKGROUND

The prevalence of lower urinary tract symptoms suggestive of benign prostatic hyperplasia (LUTS/BPH) remains high in men. However, whether reduced sleep duration enhances the risk of LUTS/BPH remains unknown.

MATERIALS AND METHODS

The 2015 China Health and Retirement Longitudinal Study was used in this study. Binary logistic regression was adopted to test the relationship between sleep duration and LUTS/BPH. Restricted cubic spline (RCS) regression was used to examine the non-linear association. In sensitivity analyses, propensity scores matching was performed to verify the robustness of the results.

RESULTS

In this study, 8,920 males aged 40 years above were enrolled. In the fully adjusted logistic model, across the quartiles of sleep duration, the odds ratios of LUTS/BPH were 1.00 (reference), 0.94 (95% CI 0.77-1.15), 0.74 (95% CI 0.58-0.94), 0.54 (0.37-0.75), respectively. The results of RCS indicated a non-linear inverted U-shaped association between sleep duration and LUTS/BPH (p for non-linearity <0.05). In the subgroup analyses, no significant effects of settlements, alcohol and cigarette consumption, depression, and hypertension on the association between sleep duration and prevalent LUTS/BPH were observed (p for interaction >0.05).

CONCLUSION

Reduced sleep duration is significantly associated with the increases of the LUTS/BPH risk in Chinese middle-aged and elderly males.

Evaluation of HIF-1 Involvement in the BDNF and ProBDNF Signaling Pathways among Obstructive Sleep Apnea Patients

Obstructive Sleep Apnea (OSA) is a chronic condition characterized by intermittent hypoxia associated with multiple comorbidities, including psychiatric disorders, such as depression, insomnia, and cognitive impairment. The brain-derived neurotrophic factor (BDNF) and proBDNF singling pathways have been shown to be involved in this group of diseases. Furthermore, their expression might be affected by hypoxia-inducible factor 1 (HIF-1), which is an oxygen sensitive transcription factor due to its alpha subunit. Therefore, this study aimed to evaluate the association between HIF-1α, BDNF, and proBDNF protein levels among OSA patients. This study included 40 individuals who underwent polysomnography (PSG) and were divided into the OSA group (n = 20; AHI ≥ 30) and healthy control (n = 20; AHI < 5) based on the apnea−hypopnea index (AHI). All participants had their peripheral blood collected in the evening before and the morning after the PSG. BDNF, proBDNF, and HIF-1α protein concertation measurements were performed using ELISA. No differences were found in BDNF, proBDNF, and HIF-1α protein levels between OSA and the control group, both in the evening and in the morning. In the OSA group, i.e., the linear regression model, the morning BDNF protein level was predicted by age (ß = −0.389, p = 0.023) and the mean SpO2 of desaturations during sleep (ß = −0.577, p = 0.002). This model accounted for 63.3% of the variability in the morning BDNF protein level (F = 14.639, p < 0.001). The morning proBDNF protein level was predicted by age (ß = −0.395, p = 0.033) and HIF-1α morning protein level (ß = −3.192, p = 0.005). This model accounted for 52.4% of the variability in the morning BDNF protein level (F = 9.355, p = 0.002). The obtained results suggest that the HIF-1 transcription factor might be involved in the pathway activated by proBDNF, which may have protective properties from hypoxia in OSA patients.

A Case-Control Study on the Changes in High-Sensitivity C-Reactive Protein and Tumor Necrosis Factor-Alpha Levels with Surgical Treatment of OSAS

Obstructive sleep apnea syndrome (OSAS) is a common but underdiagnosed condition with significant health and economic implications for society. Inflammatory mediators are proposed to be associated with the presence and severity of OSAS and contribute to morbidity and mortality. This paper details a prospective non-randomized case control study of a cohort of subjects, who underwent surgical treatment of OSAS and were enrolled to assess the sleep parameters and blood levels of selected inflammatory markers at pre-operative and post-operative time points, also comparing them to the levels in a control group. A total of 25 study subjects and 18 control subjects were enrolled. Median values and interquartile range (IQR) of the apnea-hypopnea index (AHI) in the study group pre-operatively and post-operatively were 34 (18.5-45.5) and 13.3 (7.5-27.3), while in the control group 1.4 (1.0-2.1) per hour. The mean (IQR) hs-CRP levels (mg/L) were 1.782 (0.941-5.594) and 1.980 (0.990-5.445) in the study group, pre-operatively and post-operatively, respectively, while 0.891 (0.767-1.436) in the control group. The mean (IQR) TNF-α levels (pg/mL) were 7.999 (6.137-9.216) and 6.614 (5.534-7.460) pre-and post-operatively, respectively, and were 6.000 (5.026-6.823) in the control group. Results demonstrated that both inflammatory markers, hs-CRP and TNF-α, are higher in subjects with OSAS compared to the controls, and their levels decrease, but are still higher than the controls, after successful surgical treatment. Further analysis including the body mass index and age demonstrated that these changes were significant for TNF-α, but not hs-CRP.

Blood-based lipidomic signature of severe obstructive sleep apnoea in Alzheimer's disease

Background

Obstructive sleep apnoea (OSA) is the most frequent form of sleep-disordered breathing in patients with Alzheimer’s disease (AD). Available evidence demonstrates that both conditions are independently associated with alterations in lipid metabolism. However, it is unknown whether the expression of lipids is different between AD patients with and without severe OSA. In this context, we examined the plasma lipidome of patients with suspected OSA, aiming to identify potential diagnostic biomarkers and to provide insights into the pathophysiological mechanisms underlying the disease.

Methods

The study included 103 consecutive patients from the memory unit of our institution with a diagnosis of AD. The individuals were subjected to overnight polysomnography (PSG) to diagnose severe OSA (apnoea-hypopnea index ≥30/h), and blood was collected the following morning. Untargeted plasma lipidomic profiling was performed using liquid chromatography coupled with mass spectrometry.

Results

We identified a subset of 44 lipids (mainly phospholipids and glycerolipids) that were expressed differently between patients with AD and severe and nonsevere OSA. Among the lipids in this profile, 30 were significantly correlated with specific PSG measures of OSA severity related to sleep fragmentation and hypoxemia. Machine learning analyses revealed a 4-lipid signature (phosphatidylcholine PC(35:4), cis-8,11,14,17-eicosatetraenoic acid and two oxidized triglycerides (OxTG(58:5) and OxTG(62:12)) that provided an accuracy (95% CI) of 0.78 (0.69–0.86) in the detection of OSA. These same lipids improved the predictive power of the STOP-Bang questionnaire in terms of the area under the curve (AUC) from 0.61 (0.50–0.74) to 0.80 (0.70–0.90).

Conclusion

Our results show a plasma lipidomic fingerprint that allows the identification of patients with AD and severe OSA, allowing the personalized management of these individuals. The findings suggest that oxidative stress and inflammation are potential prominent mechanisms underlying the association between OSA and AD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13195-022-01102-8.

Cluster Analysis of Home Polygraphic Recordings in Symptomatic Habitually-Snoring Children: A Precision Medicine Perspective

(1) Background: Sleep-disordered breathing (SDB) is a frequent problem in children. Cluster analyses offer the possibility of identifying homogeneous groups within a large clinical database. The application of cluster analysis to anthropometric and polysomnographic measures in snoring children would enable the detection of distinctive clinically-relevant phenotypes; (2) Methods: We retrospectively collected the results of nocturnal home-based cardiorespiratory polygraphic recordings and anthropometric measurements in 326 habitually-snoring otherwise healthy children. K-medoids clustering was applied to standardized respiratory and anthropometric measures, followed by Silhouette-based statistics. Respiratory Disturbance Index (RDI) and oxygen desaturation index (≤3%) were included in determining the optimal number of clusters; (3) Results: Mean age of subjects was 8.1 ± 4.1 years, and 57% were males. Cluster analyses uncovered an optimal number of three clusters. Cluster 1 comprised 59.5% of the cohort (mean age 8.69 ± 4.14 years) with a mean RDI of 3.71 ± 3.23 events/hour of estimated sleep (e/ehSleep). Cluster 2 included 28.5% of the children (mean age 6.92 ± 3.43 years) with an RDI of 6.38 ± 3.92 e/ehSleep. Cluster 3 included 12% of the cohort (mean age 7.58 ± 4.73 years) with a mean RDI of 25.5 ± 19.4 e/ehSleep. Weight z-score was significantly lower in cluster 3 [-0.14 ± 1.65] than in cluster 2 [0.86 ± 1.78; p = 0.015] and cluster 1 [1.04 ± 1.78; p = 0.002]. Similar findings emerged for BMI z scores. However, the height z-score was not significantly different among the 3 clusters; (4) Conclusions: Cluster analysis of children who are symptomatic habitual snorers and are referred for clinical polygraphic evaluation identified three major clusters that differed in age, RDI, and anthropometric measures. An increased number of children in the cluster with the highest RDI had reduced body weight. We propose that the implementation of these approaches to a multicenter-derived database of home-based polygraphic recordings may enable the delineation of objective unbiased severity categories of pediatric SDB. Our findings could be useful for clinical implementation, formulation of therapeutic decision guidelines, clinical management, prevision of complications, and long-term follow-up.

The Influence of Sleep Disturbance on Chronic Pain

PURPOSE OF REVIEW

The purpose of this review is to present an overview of common sleep disturbance pathologies and their impact on chronic pain, while examining various factors that are implicit in the relationship between sleep disturbance and chronic pain, including neurobiochemistry, anatomy, and systemic mediators, and reviewing recent and landmark literature.

RECENT FINDINGS

Earlier literature reviews and studies have introduced the bidirectional relationship between sleep disturbance and chronic pain; that is, impaired sleep may worsen chronic pain, and chronic pain causes sleep disturbance. However, more recent reviews and studies seem to show a more associative, rather than causative relationship. There have been recent studies that attempt to determine mechanisms that link sleep disturbance and chronic pain; the results of these studies were more varied, ultimately concluding that there may be a separate, yet-to-be discovered mechanism that shows the causative relationship between sleep disturbance and pain. There are several neurotransmitters that are involved in the mediation of chronic pain and sleep disturbance as separate entities, and some studies have shown that there may be mechanisms that govern both chronic pain and sleep disturbance as a single unit. Other neuroendocrine substances also serve to mediate chronic pain and sleep disturbance. All these substances are found to be associated with various sleep disorders and are also associated with chronic pain symptoms as well. Inflammation plays a role in chronic pain and sleep disturbance, with an increase in inflammatory substances and mediators associated with an increase or worsening in chronic pain symptoms and sleep disorders. The HPA axis plays a role in chronic pain and sleep disorders, influencing pain and sleep pathways through stress response, inflammation, and maintenance of homeostasis. There are several variables that influence both chronic pain and sleep disturbance, and more research into these variables may further our understanding into the complex pathways governing the influence of sleep disturbance on pain, and ultimately to improve treatment for this issue.

The Role of Inflammation in Cognitive Impairment of Obstructive Sleep Apnea Syndrome

Obstructive sleep apnea syndrome (OSAS) has become a major worldwide public health concern, given its global prevalence. It has clear links with multiple comorbidities and mortality. Cognitive impairment is one related comorbidity causing great pressure on individuals and society. The clinical manifestations of cognitive impairment in OSAS include decline in attention/vigilance, verbal–visual memory loss, visuospatial/structural ability impairment, and executive dysfunction. It has been proven that chronic intermittent hypoxia (CIH) may be a main cause of cognitive impairment in OSAS. Inflammation plays important roles in CIH-induced cognitive dysfunction. Furthermore, the nuclear factor kappa B and hypoxia-inducible factor 1 alpha pathways play significant roles in this inflammatory mechanism. Continuous positive airway pressure is an effective therapy for OSAS; however, its effect on cognitive impairment is suboptimal. Therefore, in this review, we address the role inflammation plays in the development of neuro-impairment in OSAS and the association between OSAS and cognitive impairment to provide an overview of its pathophysiology. We believe that furthering the understanding of the inflammatory mechanisms involved in OSAS-associated cognitive impairment could lead to the development of appropriate and effective therapy.

Later sleep timing and social jetlag are related to increased inflammation in a population with a high proportion of OSA: findings from the Cleveland Family Study

STUDY OBJECTIVES

To examine the association between sleep midpoint and inflammation in a population with a large proportion of individuals diagnosed with obstructive sleep apnea syndrome (OSAS), a group that is already prone to increased inflammation.

METHODS

Subjects from the Cleveland Family Study underwent overnight polysomnography and completed surveys on sleep habits. Morning and evening blood samples were collected and assayed for proinflammatory biomarkers interleukin (IL)-1, IL-6, and tumor necrosis factor α (TNF-α). Linear regression models were used, adjusting for potential confounders and sleep duration.

RESULTS

The study population included 587 adults (52.3% with OSAS). Mean ± standard deviation weekday sleep midpoint was 3.52 ± 2.09 (3:31 am) and weekend sleep midpoint was 4.46 ± 1.69 (4:28 am). The Mean difference between weekday and weekend sleep midpoint (social jetlag) was 0.94 ± 2.08 hours. After adjusting for OSA severity, greater social jetlag was associated with higher levels of the inflammatory cytokine IL-1 (beta: 0.435 pg/mL, 95% confidence interval [CI]: 0.091 to 0.779). Additionally, later timing of sleep during both the weekdays and the weekends was associated with increased levels of IL-6 (weekday beta: 0.182 pg/mL; 95% CI: 0.013 to 0.350; and weekend beta: 0.188 pg/mL; 95% CI: 0.004 to 0.373). No trends were observed with TNF-α and any sleep exposure.

CONCLUSIONS

Later sleep timing was associated with elevated levels of IL-6 while increased social jetlag was associated with elevated levels of IL-1. Our results indicate that later sleep schedules and increased social jetlag may lead to higher inflammation, even after controlling for OSA severity.

CITATION

Girtman KL, Baylin A, O'Brien LM, Jansen EC. Later sleep timing and social jetlag are related to increased inflammation in a population with a high proportion of OSA: findings from the Cleveland Family Study. J Clin Sleep Med. 2022;18(9):2179-2187.

Effects of oral appliances on serum cytokines in adults with obstructive sleep apnea: a systematic review

PURPOSE

This review aimed to evaluate the effects of oral appliance (OA) therapy on serum inflammatory cytokines in adults diagnosed with obstructive sleep apnea (OSA).

METHODS

Seven electronic databases and partial gray literature were searched without restrictions through March 2021. Articles evaluating the levels of serum inflammatory cytokines in patients with OSA after OA treatment were included. The risk of bias (RoB) was assessed using the before-and-after tool or RoB 2.0. The level of certainty was assessed using the GRADE tool.

RESULTS

Five studies met the eligibility criteria. One was a randomized clinical trial (RCT), while four were non-randomized clinical trials (NRCTs). Among the studies, C-reactive protein (CRP), IL-6, IL-10, IL-1β, and tumor necrosis factor α (TNF-α) were investigated. The RCT reported no significant differences in marker levels after 2 months of OA therapy, while the NRCTs showed improvement on CRP, TNF-α, and IL-1β levels after longer follow-up periods. The RoB was evaluated as showing some concern in the RCT. Three NRCTs presented good RoB, and one showed a fair RoB. The level of certainty was graded as moderate quality for inflammatory marker levels assessed in the RCT The levels of certainty evaluated in NRCTs were classified as very low.

CONCLUSIONS

Although limited, existing scientific evidence showed that OA therapy may improve serum cytokine levels in adults with OSA. However, short treatment periods are not effective in reducing markers of systemic inflammation which may require extended time and a decrease of in apneic events to improve.

Allergic rhinitis and sleep disorders in children - coexistence and reciprocal interactions

OBJECTIVE

To review, critically analyze and synthesize knowledge from the international literature regarding the association between allergic rhinitis (AR) and sleep disorders, the impact of AR treatment on children's sleep, and lay the foundation for future research on this topic.

SOURCE OF DATA

A literature search using PubMed database including original and review articles, systematic reviews and meta-analyses using keywords related to AR, sleep disorders and sleep-disordered breathing.

SYNTHESIS OF DATA

Sleep is fundamental to health, and its assessment and control of conditions that trigger or aggravate disturbances are of the uttermost importance. Allergic rhinitis (AR) is common in children and may interfere with both their quality of life and quality of sleep. It has emerged as one of the most important risk factors for habitual snoring in children and appeared to increase the risk of Obstructive Sleep Apnea (OSA), with AR severity exhibiting a significant and independent association with pediatric OSA severity. However, in some studies, those associations between AR and OSA in children are not very consistent.

CONCLUSIONS

A substantial level of controversy exists regarding the interactions between AR and OSA in children. Notwithstanding, identifying and treating AR in clinical settings is probably an important step toward improving symptoms and preventing deterioration of sleep quality in children and may improve the severity of underlying OSA. Considering the high prevalence, morbidity, economic and social implications of both AR and sleep problems, it is crucial that healthcare providers improve their understanding of the relationships between those conditions among children.

The Role of Inflammation, Hypoxia, and Opioid Receptor Expression in Pain Modulation in Patients Suffering from Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a relatively common disease in the general population. Besides its interaction with many comorbidities, it can also interact with potentially painful conditions and modulate its course. The association between OSA and pain modulation has recently been a topic of concern for many scientists. The mechanism underlying OSA-related pain connection has been linked with different pathophysiological changes in OSA and various pain mechanisms. Furthermore, it may cause both chronic and acute pain aggravation as well as potentially influencing the antinociceptive mechanism. Characteristic changes in OSA such as nocturnal hypoxemia, sleep fragmentation, and systemic inflammation are considered to have a curtailing impact on pain perception. Hypoxemia in OSA has been proven to have a significant impact on increased expression of proinflammatory cytokines influencing the hyperalgesic priming of nociceptors. Moreover, hypoxia markers by themselves are hypothesized to modulate intracellular signal transduction in neurons and have an impact on nociceptive sensitization. Pain management in patients with OSA may create problems arousing from alterations in neuropeptide systems and overexpression of opioid receptors in hypoxia conditions, leading to intensification of side effects, e.g., respiratory depression and increased opioid sensitivity for analgesic effects. In this paper, we summarize the current knowledge regarding pain and pain treatment in OSA with a focus on molecular mechanisms leading to nociceptive modulation.

Joint detection of miR ‐149‐3p and hepcidin predicts the onset of obstructive sleep apnea syndrome in obese patients

Background

Methods

Results

Conclusion

miR-199a-5p Relieves Obstructive Sleep Apnea Syndrome-Related Hypertension by Targeting HIF-1α

Introduction. Obstructive sleep apnea syndrome (OSAS) is related to hypertension. Vascular remodeling is both the pathogenesis and the structural change basis of OSAS-related hypertension. Exploring miRNA functioning in OSAS-related hypertension may offer novel diagnostic and therapeutic targets for controlling hypertension-associated cardiovascular diseases. However, the role of miR-199a-5p in OSAS-related hypertension has not been demonstrated yet. Methods. In this study, we investigated the role of miR-199a-5p and HIF-1α in OSAS-related hypertension by performing in vitro cell experiments and in vivo animal experiments. Rat aortic smooth muscle cells (A7r5) were cultured under hypoxia as an in vitro model. To establish the animal model of OSAS-related hypertension, the rats were under exposure to chronic intermittent hypoxia (CIH) in a hypoxic instrument. The rats were randomly grouped into normal, CIH, CIH+NC, and CIH+miR-199a-5p. Results. By establishing an animal model, we found decreased miR-199a-5p expression and increased HIF-1α expression in OSAS with hypertension. The overexpressed miR-199a-5p could reduce systolic blood pressure and relieve oxidase stress and inflammation. miR-199a-5p treatment could overturn the upregulation of HIF-1α and TGF-β1 and downregulation of α-SMA. Overexpressed miR-199a-5p might attenuate vascular remodeling through HIF-1α downregulation. miR-199a-5p/HIF-1α may inhibit proliferation of vascular smooth muscle cells under hypoxia. Conclusion. miR-199a-5p may relieve OSAS-related hypertension by targeting HIF-1α and be a novel potential therapeutic target.

Multiple Machine Learning Methods Reveal Key Biomarkers of Obstructive Sleep Apnea and Continuous Positive Airway Pressure Treatment

Obstructive sleep apnea (OSA) is a worldwide health issue that affects more than 400 million people. Given the limitations inherent in the current conventional diagnosis of OSA based on symptoms report, novel diagnostic approaches are required to complement existing techniques. Recent advances in gene sequencing technology have made it possible to identify a greater number of genes linked to OSA. We identified key genes in OSA and CPAP treatment by screening differentially expressed genes (DEGs) using the Gene Expression Omnibus (GEO) database and employing machine learning algorithms. None of these genes had previously been implicated in OSA. Moreover, a new diagnostic model of OSA was developed, and its diagnostic accuracy was verified in independent datasets. By performing Single Sample Gene Set Enrichment Analysis (ssGSEA) and Counting Relative Subsets of RNA Transcripts (CIBERSORT), we identified possible immunologic mechanisms, which led us to conclude that patients with high OSA risk tend to have elevated inflammation levels that can be brought down by CPAP treatment.

Obstructive Sleep Apnea and Cardiovascular Risk: The Role of Dyslipidemia, Inflammation, and Obesity

Introduction: The present study aimed to establish the role of lipid abnormalities and inflammatory markers for developing cardiovascular risk, as well as to address the importance of obesity as a common comorbidity in patients with obstructive sleep apnea (OSA).

Methods: The study was conducted as a prospective cohort study including 120 patients with newly diagnosed OSA between 2019 and 2020, at University Clinical Hospital Center “Bezanijska kosa”, Belgrade, Serbia. The diagnosis was established by polysomnography. In all patients, sociodemographic data, respiratory, lipid, and inflammatory parameters were collected and complete echocardiographic study and 24-h blood pressure monitoring were performed.

Results: The mean patient age was 55.7 ± 13.8 years. Study population was mostly male (70.0%) and obese (56.7%). At least 30 apneas or hypopneas per hour were present in 39.0% of patients. A strong positive correlation was found between OSA severity and BMI (r = 0.562, p < 0.001), both associated with lipid, inflammatory and respiratory parameters, and cardiovascular profile of patients with OSA (p < 0.05 for all). Echocardiographic study and 24-h blood pressure monitoring parameters were in turn correlated with lipid and inflammatory markers (p < 0.05 for all).

Conclusion: The results of this study support the important role of dyslipidemia and inflammation, as well as coexistence of obesity in the pathogenesis of numerous conditions linked with an increased risk of cardiovascular morbidity and mortality in patients with OSA.

Influence of obstructive sleep apnea on postoperative cognitive dysfunction in elderly patients undergoing joint replacement

OBJECTIVE

To clarify the influence of obstructive sleep apnea (OSA) on postoperative cognitive dysfunction (POCD) in elderly patients undergoing joint replacement.

METHODS

This study retrospectively enrolled130 patients who underwent joint replacement in the Department of Orthopaedics of Taizhou Municipal Hospital between January 2019 and March 2021 for analysis. According to polysomnography (PSG) results, 80 patients without OSA were included in group A and 50 with OSA were assigned to group B. The two groups were compared with respect to the following items: surgical indications (length of stay (LOS), intraoperative blood loss (IBL) and operation time (OT), incidence of postoperative delirium (POD), postoperative cognitive function (Mini-mental State Examination, MMSE), neurological function recovery (National Institutes of Health Stroke Scale, NIHSS) and (Scandinavian Stroke Scale, SSS)), mental health (Self-Rating Anxiety Scale (SAS) and Self-Rating Depression Scale (SDS)), compliance, overall response rate (ORR), complications and patient satisfaction.

RESULTS

The LOS and OT were shorter, and the IBL was less in group A compared with those in group B. Group A also showed reduced NIHSS and SSS scores as well as SAS and SDS scores when compared with group B. In addition, lower incidence of POD, and higher compliance, ORR and satisfaction were observed in group A than in group B. In terms of cognitive function, although the MMSE score in both groups decreased after surgery, patients in group B had a lower MMSE score and a milder form of POCD.

CONCLUSIONS

OSA may affect the postoperative cognitive function and adversely influence the treatment outcome of elderly patients undergoing joint replacement.

Correlation of Dyslipidemia and Inflammation With Obstructive Sleep Apnea Severity

Introduction: Obstructive sleep apnea (OSA) is a serious condition linked with various metabolic disorders and associated with increased all-cause and cardiovascular mortality. Although the potential mechanisms of pathophysiological processes related to OSA are relatively well known, the data regarding the correlation between obstructive sleep apnea, dyslipidemia, and systemic inflammation are still inconclusive.

Methods: The study was conducted as a retrospective cohort study including 328 patients with newly diagnosed obstructive sleep apnea during the period between April 2018, and May 2020, in University Clinical Hospital Center “Bezanijska kosa”, Belgrade, Serbia. Polysomnography was performed in all patients according to the protocol. Numerous demographic, antropometric, laboratory, and clinical data were correlated to Apnea-Hypopnea Index (AHI) as a dependent variable, with a particular review on the relation between lipid abnormalities, inflammatory parameters, and obstructive sleep apnea severity. Multivariate logistic regression model was used to assess predictors of severe OSA (AHI ≥30 per hour).

Results: A total of 328 patients were included in the study. The mean age of the patients was 54.0 ± 12.5 years and more than two-thirds were male (68.8%). The majority of the patients had an AHI of at least 30 events per hour. Patients with severe OSA were more frequently male, obese, hypertensive and hyperlipidemic, and had increased neck circumference (both male and female patients). One hundred and thirty-two patients had metabolic syndrome. Patients with severe OSA more frequently had metabolic syndrome and significantly higher levels of glucose, creatinine, uric acid, AST, ALT, CK, microalbumine/creatinine ratio, triglyceride, total cholesterol, HDL, total cholеsterol to HDL‐C ratio, CRP, and ESR. In the multivariate linear regression model with AHI (≥30 per hour) as a dependent variable, of demographic and clinical data, triglycerides ≥1.7 mmol/L and CRP >5 mg/L were significantly associated with AHI≥30 per hour.

Conclusion: The present study on 328 patients with newly diagnosed obstructive sleep apnea revealed significant relation of lipid abnormalities, inflammatory markers, and other clinically important data with obstructive sleep apnea severity. These results can lead to a better understanding of the underlying pathophysiological processes and open the door to a new world of potentially useful therapeutic modalities.

Obstruktive Schlafapnoe und arterielle Hypertonie

Hintergrund

In Deutschland leiden rund 19 Mio. Patienten an einer diagnostizierten arteriellen Hypertonie (aHT). Die Schnittmenge zwischen Menschen mit aHT und obstruktiver Schlafapnoe (OSA) ist groß. Aufwachreaktionen und Hypoxämie im Rahmen einer OSA können zu einem gesteigerten Sympathikotonus und endothelialer Dysfunktion und somit zu aHT führen.

Fragestellung

Der vorliegende Übersichtsartikel soll die Zusammenhänge zwischen OSA und aHT sowie Behandlungsmöglichkeiten darstellen.

Materialien und Methoden

Es erfolgte eine Literaturrecherche von Original- und Übersichtsartikeln, die bis 2021 in der PubMed-Datenbank veröffentlicht wurden.

Ergebnisse

Obstruktive Schlafapnoe kann sowohl die Entstehung als auch die Verschlechterung einer aHT verursachen. Betroffene profitieren von einer CPAP-Behandlung mit einer durchschnittlichen Senkung des systolischen Blutdrucks um −4,4 mm Hg sowie des diastolischen Blutdrucks um −2,9 mm Hg. Prädiktoren für eine Reduktion des Blutdrucks unter kontinuierlicher Positivdrucktherapie (CPAP) sind junges Alter, therapieresistente aHT, schwere OSA-bedingte Sauerstoffentsättigungen und ein „Non-Dipping-Blutdruckmuster“.

Schlussfolgerung

Die adäquate Behandlung einer aHT fordert häufig einen multimodalen Ansatz. Neben einer medikamentösen antihypertensiven Therapie und einer Modifikation des Lebensstils sollte auch die Diagnose und gegebenenfalls die Behandlung einer OSA berücksichtigt werden.

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.

VEGF Receptor 1 Promotes Hypoxia-Induced Hematopoietic Progenitor Proliferation and Differentiation

Although it is well known that hypoxia incites unleashed cellular inflammation, the mechanisms of exaggerated cellular inflammation in hypoxic conditions are not known. We observed augmented proliferation of hematopoietic stem and progenitor cells (HSPC), precursors of inflammatory leukocytes, in mice under hypoxia. Consistently, a transcriptomic analysis of human HSPC exposed to hypoxic conditions revealed elevated expression of genes involved in progenitor proliferation and differentiation. Additionally, bone marrow cells in mice expressed high amount of vascular endothelial growth factor (VEGF), and HSPC elevated VEGF receptor 1 (VEGFr1) and its target genes in hypoxic conditions. In line with this, VEGFr1 blockade in vivo and in vitro decreased HSPC proliferation and attenuated inflammation. In silico and ChIP experiments demonstrated that HIF-1α binds to the promoter region of VEGFR1. Correspondingly, HIF1a silencing decreased VEGFr1 expression in HSPC and diminished their proliferation. These results indicate that VEGF signaling in HSPC is an important mediator of their proliferation and differentiation in hypoxia-induced inflammation and represents a potential therapeutic target to prevent aberrant inflammation in hypoxia-associated diseases.

Changes of circulating biomarkers of inflammation and glycolipid metabolism by CPAP in OSA patients: a meta-analysis of time-dependent profiles

Background:

Continuous positive airway pressure (CPAP) is the first-line therapy for moderate-to-severe obstructive sleep apnea (OSA). Specifying timing of CPAP benefits on OSA-related biomarkers will help to assess the effectiveness of CPAP and to optimize the treatment strategies.

Purpose:

To explore the time-dependent changes of circulating biomarkers to CPAP treatment in patients with OSA, including inflammatory biomarkers [C-reactive protein (CRP) and tumor necrosis factor–α (TNF-α)] and glycolipid metabolic biomarkers [fasting blood glucose (FBG), fasting insulin (FINS), low-density lipoprotein (LDL), high-density lipoprotein (HDL), total cholesterol (TC), and triglyceride (TG)].

Methods:

Searches of PubMed and Embase database were completed. Two independent reviewers extracted data from 68 included studies. A meta-analysis was conducted using a random-effect (or fixed-effect) model and standardized mean difference (SMD) model. The timing profiles of circulating biomarkers changes of inflammation and glycolipid metabolism were analyzed based on different CPAP duration, that is, short-term (<3 months), mid-term (3–6 months), and long-term (⩾6 months).

Results:

Those first improved by short-term treatment include CRP [SMD: 0.73, 95% confidence interval (CI): 0.15–1.31; p = 0.014], TNF-α [SMD: 0.48 (95% CI: 0.10–0.86; p = 0.014)], FBG [SMD: 0.32 (95% CI: 0.07–0.57; p = 0.011)], and LDL [SMD: 0.40 (95% CI: 0.18–0.62; p = 0.000)]. Those first improved by the mid-term or long-term treatment include HDL [SMD: –0.20 (95% CI: –0.36 to –0.03; p = 0.018)] and TC [SMD: 0.20 (95% CI: 0.05–0.34; p = 0.007)]. There were insignificant changes for TG and FINS after short or long CPAP.

Conclusion:

Our results imply that changes of circulating biomarkers for patients with OSA under CPAP treatment have a time-dependent profile.

Mechanism of SMND-309 against lung injury induced by chronic intermittent hypoxia

INTRODUCTION

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is a common sleep disorder that causes severe physiological disturbance. Evidence showed that OSAHS is an important associated comorbidity that can affect the survival of patients with pulmonary fibrosis. Until now, the potential mechanisms by which OSAHS accelerates the progression of lung fibrosis remain unclear. By constructing a pathological model of chronic intermittent hypoxia (CIH), the present study aimed to explore the pathological progress and potential mechanism of lung injury caused by OSAHS. Meanwhile, SMND-309 was given for treatment to evaluate its potential therapeutic role in CIH-induced lung injury.

METHODS

Mice were randomly divided into (C57BL/6 wild-type) WT+(room air) RA, WT + CIH, SMND-309 + RA, and SMND-309 + CIH groups. The WT + CIH and SMND-309 + CIH groups were exposed to CIH condition for 12 weeks, while the other groups were processed in normal oxygen at the same time. The SMND-309 + RA and SMND-309 + CIH groups were intraperitoneally injected with SMND-309 at the last week of the modeling period. After 12 weeks of treatment, three mice from each group were perfused through the heart. Lung tissues were isolated, fixed, sectioned, and stained with H&E, Masson, and immunofluorescence stain. The rest of the lung tissues were harvested for Western blot and ELISA assays.

RESULTS

CIH treatment increased the expression of pro-inflammatory factors (TNF-α and IL-6), resulting in lung tissue structure disorder, inflammatory cell infiltration, increased pulmonary capillary permeability, and pulmonary edema. The activation of the NF-κB signaling pathway played a crucial role in the process of inflammation. Noticeably, we observed M2 macrophage accumulation in the lung after CIH exposure, which promoted epithelial-mesenchymal transition (EMT) and pulmonary tissue fibrosis. ELISA assays showed the increased expression of TGF-β, IL-10, and IL-4 in the CIH group. SMND-309 inhibited pulmonary inflammation, reduced the accumulation of M2 macrophage, alleviated collagen deposition andlung damage.

CONCLUSION

CIH could induce chronic lung inflammation, promote the activation of M2 macrophages, trigger the occurrence of EMT, and accelerate the deposition of lung collagen, eventually leading to lung tissue damage. This study presents a possible explanation by which interstitial lung diseases, particularly idiopathic pulmonary fibrosis (IPF) with OSAHS, are usually associated with fast progress and poor prognosis. SMND-309 showed a good protective effect on CIH-induced lung damage.

Obstructive Sleep Apnea Affects Lacrimal Gland Function

Purpose

To determine the effect of obstructive sleep apnea syndrome (OSA) on lacrimal gland function and its mechanism.

Methods

Male mice aged seven to eight weeks were housed in cages with cyclic intermittent hypoxia to mimic OSA, and the control group was kept in a normal environment. Slit-lamp observation, fluorescein staining, and corneal sensitivity detection are used to assess cornea changes. Tear secretion was detected by phenol red cotton thread, and the pathological changes of lacrimal gland were observed by hematoxylin and eosin staining, oil red O staining, cholesterol and triglyceride kits, immunofluorescence staining, immunohistochemical staining, real-time polymerase chain reaction, transmission electron microscopy, and Western blot.

Results

Studies revealed a decreased tear secretion, corneal epithelial defects and corneal hypersensitivity. Myoepithelial cell damage, abnormal lipid accumulation, reduced cell proliferation, increased apoptosis and inflammatory cell infiltration in the lacrimal gland were also seen. Hifα and NF-κB signaling pathways, moreover, were activated, while Pparα was downregulated, in the lacrimal glands of OSA mice. Fenofibrate treatment significantly alleviated pathological changes of the lacrimal gland induced by OSA.

Conclusion

OSA disturbs the Hifα/Pparα/NF-κB signaling axis, which affects lacrimal gland structure and function and induces dry eye.

Effectiveness of a Uniquely Designed Oral Appliance on Obstructive Sleep Apnea Control: A Pilot Study

Objectives  Obstructive sleep apnea is an inflammatory, chronic, and evolutive disease often needing adequate treatment and follow-up. The oral appliance (OA) is an accepted alternative therapy for obstructive sleep apnea (OSA) control. Due to greater adherence, OA with mandibular advancement (OA _m ) is being recommended treatment for patients who refuse or do not tolerate continuous positive airway pressure. The mode of action of OA _m is to promote the advancement of the mandible or tongue with a subsequent increase in the tone of the pharyngeal muscles and the permeability of the upper airway, but most OA _m use conventional models as reference, analogic, or digital, dissociating dental arches of the skull structures.

Materials and Methods  A retrospective longitudinal study of 33 OSA patient treated with a different OA _m , that use Camper plane as reference with skull structures for dental arches disocclusion, where polysomnographic, cephalometric measures, and subjective data from questionnaires pre- and post-treatment were assessed and correlated. Descriptive analysis, correlated Chi-square tests, and basic statistics were used. Generalized linear mixed model for repeated measure and post hoc Tukey–Kramer test compares the variables pre- and post-treatment. Shapiro–Wilk test and Pearson's correlation coefficients were used. All statistical tests were set in 5% level of significance.

Results  Regarding polysomnography data, there was a significant association between apnea hypopnea index (AHI) with oxygen saturation, arousal index (AI) and the maximum heartbeats, and sleep improvement and health risk reduction. Additionally, from cephalometric data, it was found a significant association between the tongue posture with the soft palate, hioyd-C3 and, lower and posterior airway. When both parameters are correlated, there are a significant dependent association with hyoid bone position with AHI and AI. The limitation of this study was the two-dimensional image used without provide volumetric measurements, but this limitation was reduced with the follow-up polysomnography parameters.

Conclusion  In this pilot study, DIORS OA _m as an uniquely designed device using Camper plane as a reference for disocclusion was effective in the control of OSA.

Inflammatory Biomarkers for Children with Sleep Disorders: A Review

Introduction Obstructive sleep apnea (OSA) syndrome is a highly prevalent problem in children. Unfortunately sleep disorders in children remain largely unreported and underdiagnosed due to various reasons. Overnight in-laboratory polysomnography (PSG) is the gold standard diagnostic method for OSA; however, it has several drawbacks. Hence there is a need for simple alternative diagnostic methods, such as biomarkers. Children with OSA seem to have an inflammatory aspect to its pathophysiology; thus the rationale for evaluating inflammatory biomarkers.

Objective This narrative review aimed to evaluate the existing knowledge regarding inflammatory biomarkers for children with sleep disorders.

Materials and Methods An extensive search of all literature linked to the topic was performed in PubMed, Medline, EBSCOhost, Cochrane library database CENTRAL, and Google Scholar search engine. Keywords used in the search included combinations of the following: inflammation, sleep disorders, children, and biomarkers. Studies in the list of references of relevant literature were also included. A total of 155 articles published in the period from 1997 to 2021 were initially included in this review. Selected articles comprised original research, meta-analysis, and systematic reviews.

Results Studies have mainly centered their investigations on serum inflammatory biomarkers, namely interleukin-6, tumor necrosis factor-α, and C-reactive protein. Very few studies investigated salivary inflammatory biomarkers in children.

Conclusion Evidence suggests that children with sleep disorders have elevated levels of salivary as well as serum inflammatory biomarkers in comparison to normal healthy children. Also increased levels of these biomarkers correlate with disease severity. However, more studies are needed to determine the sensitivity and specificity of salivary inflammatory biomarkers for children with sleep disorders.

A Population-Based Study of Patients with Sleep-Wake Disorders Undergoing Elective Instrumented Spinal Surgery

BACKGROUND

Sleep-wake disorders are associated with multisystemic pathologies, but the clinical risk that such disorders carry for spinal surgery patients is not well understood. This population-based study comprehensively evaluates the significance of sleep-related risk factors on instrumented spinal surgery outcomes.

METHODS

National Inpatient Sample data for hospitalizations of patients undergoing elective instrumented spine surgery between 2008 and 2014 was analyzed using national estimates. Cohorts were defined as those admissions with or without a coexisting sleep-wake disorder diagnosis identified by ICD-9 codes. Postoperative complications, mortality rate, length of stay, discharge status, and total cost of admission were compared between groups using bivariate and multivariate analyses.

RESULTS

A coexisting sleep-wake disorder existed in 234,640 (10.8%) of 2,171,167 instrumented spinal surgery hospitalizations. Multivariate binary logistic regression accounting for these variables confirmed that a sleep-wake disorder is a significant risk factor for postoperative complication (OR 1.160, 95% CI 1.140-1.179, p<0.0001), length of stay above the 75^th percentile (OR 1.303, 95% CI 1.288-1.320, p<0.0001), non-routine discharge (OR 1.147, 95% CI 1.131-1.163, p<0.0001), and death (OR 1.533, 95% CI 1.131-2.078, p<0.01), but not for total charges above the 75^th percentile (OR 0.975, 95% CI 0.962-0.989, p<0.001).

CONCLUSIONS

Sleep-wake disorders confer increased risk of morbidity and mortality in elective instrumented spine surgery. Understanding the specific contributions of sleep-wake disorders to postoperative morbidity and mortality can help physicians implement prophylactic measures to reduce complications and improve postoperative patient recovery.

Pediatric Obstructive Sleep Apnea: What’s in a Name?

Obstructive sleep apnea is a highly prevalent disease across the lifespan and imposes substantial morbidities, some of which may become irreversible if the condition is not diagnosed and treated in a timely fashion. Here, we focus on the clinical and epidemiological characteristics of pediatric obstructive sleep apnea, describe some of the elements that by virtue of their presence facilitate the emergence of disrupted sleep and breathing and its downstream consequences, and also discuss the potential approaches to diagnosis in at-risk children.

Prevalence and Characteristics of Sleep Apnea in Intensive Care Unit Survivors After SARS-CoV-2 Pneumonia

BACKGROUND

Sleep apnea (SA) was reported as possibly exacerbating symptoms of COVID-19, a disease induced by SARS-CoV-2 virus. The same comorbidities are common with both pathologies. This study aimed to estimate the prevalence, characteristics of SA and variation in AHI three months after severe COVID-19 requiring intensive care unit (ICU) admission.

METHODS

A prospective cohort of patients admitted to ICU for severe COVID-19 underwent an overnight home polygraphy 3 months after onset of symptoms, as part of a comprehensive follow-up program (pulmonary function tests, 6-minute walk tests and chest CT-scan). Patients with an apnea hypopnea index (AHI) ≥5 were considered as having SA. We performed a comparative descriptive analysis of 2 subgroups according to the existence, severity of SA and indication for effective SA treatment: patients with absent or mild SA (AHI <15) vs patients with moderate to severe SA (AHI ≥15).

RESULTS

Among 68 patients included, 62 (91%) had known comorbidities (34 hypertension, 21 obesity, 20 dyslipidemia, 16 type 2 diabetes). It has been observed a preexisting SA for 13 patients (19.1%). At 3 months, 62 patients (91%) had SA with 85.5% of obstructive events. Twenty-four patients had no or a mild SA (AHI <15) and 44 had moderate to severe SA (AHI ≥15). Ischemic heart disease exclusively affected the moderate to severe SA group. Except for thoracic CT-scan which revealed less honeycomb lesions, COVID-19 symptoms were more severe in the group with moderate to severe SA, requiring a longer curarization, more prone position sessions and more frequent tracheotomy.

CONCLUSION

SA involved 91% of patients in our population at 3 months of severe COVID-19 and was mainly obstructive type. Although SA might be a risk factor as well as consequences of ICU care in severe COVID-19 infection, our results underline the importance of sleep explorations after an ICU stay for this disease.

Chronic lung diseases and sleep

Sleep is vitally important part of our life. Its quality and quantity influence all physiological processes in our organism. The relationship between the lung diseases and sleep is bidirectional - the lack of quality sleep worsens the compensation and the course of the diseases and in the same time chronic lung diseases are negatively affecting sleep quality. The coexistence of the sleep disordered breathing and lung disorders is another important issue to discuss. In case of chronic obstructive pulmonary disease the overlap with sleep disordered breathing is characterized by higher prevalence of hypercapnia and overall worse prognosis. Moreover, there is a growing body of evidence about possible links of sleep disordered breathing to lung fibrosis and tumors. The complex healthcare in patients with respiratory diseases should not omit sleep examination.

Neurocognitive Performance Improvement after Obstructive Sleep Apnea Treatment: State of the Art

Background: Obstructive Sleep Apnea (OSA) syndrome is a respiratory sleep disorder characterized by partial or complete episodes of upper airway collapse with reduction or complete cessation of airflow. Although the connection remains debated, several mechanisms such as intermittent hypoxemia, sleep deprivation, hypercapnia disruption of the hypothalamic–pituitary–adrenal axis have been associated with poor neurocognitive performance. Different treatments have been proposed to treat OSAS patients as continuous positive airway pressure (CPAP), mandibular advancement devices (MAD), surgery; however, the effect on neurocognitive functions is still debated. This article presents the effect of OSAS treatments on neurocognitive performance by reviewing the literature. Methods: We performed a comprehensive review of the English language over the past 20 years using the following keywords: neurocognitive performance and sleep apnea, neurocognitive improvement and CPAP, OSAS, and cognitive dysfunction. We included in the analysis papers that correlated OSA treatment with neurocognitive performance improvement. All validated tests used to measure different neurocognitive performance improvements were considered. Results: Seventy papers reported neurocognitive Performance improvement in OSA patients after CPAP therapy. Eighty percent of studies found improved executive functions such as verbal fluency or working memory, with partial neural recovery at long-term follow-up. One article compared the effect of MAD, CPAP treatment on cognitive disorders, reporting better improvement of CPAP and MAD than placebo in cognitive function. Conclusions: CPAP treatment seems to improve cognitive defects associated with OSA. Limited studies have evaluated the effects of the other therapies on cognitive function.

Enhanced Ocular Surface and Intraoral Nociception via a Transient Receptor Potential Vanilloid 1 Mechanism in a Rat Model of Obstructive Sleep Apnea

Obstructive sleep apnea (OSA), characterized by low arterial oxygen saturation during sleep, is associated with an increased risk of orofacial pain. In this study, we simulated chronic intermittent hypoxia (CIH) during the sleep/rest phase (light phase) to determine the role of transient receptor potential vanilloid 1 (TRPV1) in mediating enhanced orofacial nocifensive behavior and trigeminal spinal subnucleus caudalis (Vc) neuronal responses to capsaicin (a TRPV1 agonist) stimulation in a rat model of OSA. Rats were subjected to CIH (nadir O₂, 5%) during the light phase for 8 or 16 consecutive days. CIH yielded enhanced behavioral responses to capsaicin after application to the ocular surface and intraoral mucosa, which was reversed under normoxic conditions. The percentage of TRPV1-immunoreactive trigeminal ganglion neurons was greater in CIH rats than in normoxic rats and recovered under normoxic conditions after CIH. The ratio of large-sized TRPV1-immunoreactive trigeminal ganglion neurons increased in CIH rats. The density of TRPV1 positive primary afferent terminals in the superficial laminae of Vc was higher in CIH rats. Phosphorylated extracellular signal-regulated kinase (pERK)-immunoreactive cells intermingled with the central terminal of TRPV1-positive afferents in the Vc. The number of pERK-immunoreactive cells following low-dose capsaicin (0.33 µM) application to the tongue was significantly greater in the middle portion of the Vc of CIH rats than of normoxic rats and recovered under normoxic conditions after CIH. These data suggest that CIH during the sleep (light) phase is sufficient to transiently enhance pain on the ocular surface and intraoral mucosa via TRPV1-dependent mechanisms.

Heart failure with preserved left ventricular ejection fraction in patients with obstructive sleep apnea syndrome: prognostic value of biomarkers

Aim      To study the role of soluble ST2 (sST2), N-terminal pro-brain natriuretic peptide (NT-proBNP), and С-reactive protein (CRP) in patients with chronic heart failure and preserved left ventricular ejection fraction (CHF with pLVEF) and syndrome of obstructive sleep apnea (SOSA) in stratification of the risk for development of cardiovascular complications (CVC) during one month of a prospective observation.Material and methods  The study included 71 men with SOSA with an apnea/hypopnea index (AHI) &gt;15 per hour, abdominal obesity, and arterial hypertension. Polysomnographic study and echocardiography according to a standard protocol with additional evaluation of left ventricular myocardial fractional changes and work index were performed for all patients at baseline and after 12 months of observation. Serum concentrations of sST2 , NT-proBNP, and CRP were measured at baseline by enzyme-linked immunoassay (ELISA).Results The ROC analysis showed that the cutoff point characterizing the development of CVC were sST2 concentrations ≥29.67 ng/l (area under the curve, AUC, 0.773, sensitivity 65.71 %, specificity 86.11 %; p&lt;0.0001) while concentrations of NT-proBNP (AUC 0.619; p=0.081) and CRP (AUC 0.511; р=0.869) were not prognostic markers for the risk of CVC. According to data of the ROC analysis, all patients were divided into 2 groups based on the sST2 cutoff point: group 1 included 29 patients with ST2 ≥29.67 ng/l and group 2 included 42 patients with ST2 &lt;29.67 ng/l. The Kaplan-Meyer analysis showed that the incidence of CVC was higher in group 1 than in group 2 (79.3 and 28.6 %, respectively, p&lt;0.001). The regression analysis showed that adding values of AHI and left ventricular myocardial mass index (LVMMI) to sST2 in the model increased the analysis predictive significance.Conclusion      Measuring sST2 concentration may be used as a noninvasive marker for assessment of the risk of CVC development in patients with CHF with pLVEF and SOSA within 12 months of observation. Adding AHI and LVMMI values to the model increases the predictive significance of the analysis.

Putative associations between inflammatory biomarkers, obesity, and obstructive sleep apnea

BACKGROUND:

Previous studies have reported increased levels of inflammatory mediators in patients with obstructive sleep apnea (OSA), but their relation with the severity of OSA is controversial.

OBJECTIVE:

To address potential relationships between OSA-related inflammatory markers, namely, C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and fibrinogen, with different oxygenation parameters and with BMI.

METHODS:

All eligible patients with suspected OSA newly referred to the Sleep Medicine Research Center at King Abdulaziz University Hospital, Jeddah, were evaluated demographically and anthropometrically, and underwent overnight polysomnography. Fasting morning blood samples were collected to measure serum levels of CRP, fibrinogen, TNF-α, and IL-6. Potential correlations between these inflammatory mediators and severity measures of OSA and body mass index (BMI) were explored.

RESULTS:

Sixty-four patients completed the study (40 with OSA and 24 without OSA). Significantly increased levels of CRP, fibrinogen, IL-6, and TNF-α emerged in patients with OSA compared to non-OSA. Significant associations between log CRP and log fibrinogen levels emerged with increasing BMI. However, there was no significant association between any of the inflammatory markers and the severity of OSA based on the apnea/hypopnea index or oxyhemoglobin saturation-derived parameters.

CONCLUSIONS:

OSA patients exhibit increased levels of inflammatory mediators that do not appear to be associated with polysomnographic measures, but exhibit positive correlation with the degree of adiposity.

Oxygen saturation as a predictor of inflammation in obstructive sleep apnea

PURPOSE

Obstructive sleep apnea (OSA) is a chronic sleep disorder, and its prevalence is increasing worldwide. This disorder has been consistently associated with several comorbidities. Although it is clear that obstructive sleep apnea severity is associated with inflammation, the trigger for this phenomenon continues to puzzle scientists. Here, we investigated the relationship between obstructive sleep apnea severity and immune parameters.

METHODS

In this cross-sectional epidemiological research, we analyzed the immune profile of 461 adults according to OSA severity (mild, moderate, and severe) and oxygen saturation.

RESULTS

The hallmark of OSA severity - the apnea-hypopnea index (AHI) - weakly correlated with an inflammatory profile. However, individuals who experienced lower oxygen saturation were more likely to exhibit higher total leukocyte and neutrophil counts, a higher neutrophil-lymphocyte ratio (NLR), and an increased concentration of C-reactive protein.

CONCLUSION

Our findings indicated that oxygen saturation is a predictor of inflammation during OSA and should be considered crucial in disease diagnostic and treatment strategies.

Circulating C-reactive protein levels in patients with suspected obstructive sleep apnea

STUDY OBJECTIVES

To assess determinants of CRP in a cohort of patients referred for investigation of OSA and to determine whether overlap of OSA and COPD (overlap syndrome, OVS) is associated with higher levels of CRP.

METHODS

This was a cross-sectional study that included 2352 patients seen at the West Australian Sleep Disorders Research Institute between 2006 and 2010. All patients had circulating CRP levels, and spirometry performed. OSA was defined apnea-hypopnea index (AHI) ≥ 5 events per hour and COPD defined as FEV1/FVC ratio <0.70 and age > 40 years. Univariate and multivariate regression analysis were used to identify CRP determinants.

RESULTS

Mean age was 51 years (60% male), median (AHI) was 27 events/h, median 3% oxygen desaturation index (ODI3%) was 24 events/h, mean FEV₁ was 88% predicted, and median CRP was 3.0 mg/L. In multivariate analyses: age, body mass index, female sex, neck circumference, AHI, and desaturation markers (nadir and mean oxygen saturation) were independently associated with higher CRP. Spirometric variables were not predictors. There was no significant difference in CRP among OSA patients with or without co-existing COPD.

CONCLUSIONS

Markers of OSA severity (AHI and oxygenation), age, BMI, neck circumference and female sex were independent predictors of circulating CRP levels. OSA overlapping with COPD was not associated with increased CRP compared to either condition alone, suggesting other mechanisms for the increased CVD risk in OVS. Identification of factors that predict CRP will help identify patients at higher risk of CVD and aid risk stratification.