Systemic and airway inflammation in sleep apnea and obesity: the role of ICAM-1 and IL-8

The common link between sleep apnea syndrome and osteoarthritis: a literature review

Patients with Osteoarthritis (OA) often also suffer from Sleep Apnea Syndrome (SAS), and many scholars have started to notice this link, although the relationship between the two is still unclear. In this review, we aim to summarize the current literature on these two diseases, integrate evidence of the OA and OSA connection, explore and discuss their potential common mechanisms, and thus identify effective treatment methods for patients with both OA and SAS. Some shared characteristics of the two conditions have been identified, notably aging and obesity as mutual risk factors. Both diseases are associated with various biological processes or molecular pathways, including mitochondrial dysfunction, reactive oxygen species production, the NF-kB pathway, HIF, IL-6, and IL-8. SAS serves as a risk factor for OA, and conversely, OA may influence the progression of SAS. The effects of OA on SAS are underreported in the literature and require more investigation. To effectively manage these patients, timely intervention for SAS is necessary while treating OA, with weight reduction being a primary requirement, alongside combined treatments such as Continuous positive airway pressure (CPAP) and medications. Additionally, numerous studies in drug development are now aimed at inhibiting or clearing certain molecular pathways, including ROS, NF-KB, IL-6, and IL-8. Improving mitochondrial function might represent a viable new strategy, with further research into mitochondrial updates or transplants being essential.

Impact of obesity on airway remodeling in asthma: pathophysiological insights and clinical implications

The prevalence of obesity among asthma patients has surged in recent years, posing a significant risk factor for uncontrolled asthma. Beyond its impact on asthma severity and patients' quality of life, obesity is associated with reduced lung function, increased asthma exacerbations, hospitalizations, heightened airway hyperresponsiveness, and elevated asthma-related mortality. Obesity may lead to metabolic dysfunction and immune dysregulation, fostering chronic inflammation characterized by increased pro-inflammatory mediators and adipocytokines, elevated reactive oxygen species, and reduced antioxidant activity. This chronic inflammation holds the potential to induce airway remodeling in individuals with asthma and obesity. Airway remodeling encompasses structural and pathological changes, involving alterations in the airway's epithelial and subepithelial layers, hyperplasia and hypertrophy of airway smooth muscle, and changes in airway vascularity. In individuals with asthma and obesity, airway remodeling may underlie heightened airway hyperresponsiveness and increased asthma severity, ultimately contributing to the development of persistent airflow limitation, declining lung function, and a potential increase in asthma-related mortality. Despite efforts to address the impact of obesity on asthma outcomes, the intricate mechanisms linking obesity to asthma pathophysiology, particularly concerning airway remodeling, remain incompletely understood. This comprehensive review discusses current research investigating the influence of obesity on airway remodeling, to enhance our understanding of obesity's role in the context of asthma airway remodeling.

Association of Tumor Necrosis Factor-Alpha, Interleukin-1β, Interleukin-8, and Interferon-γ with Obstructive Sleep Apnea in Both Children and Adults: A Meta-Analysis of 102 Articles

Background: Cytokines may have a significant impact on sleep regulation. In this meta-analysis, we present the serum/plasma levels of tumor necrosis factor-alpha (TNF-α), interleukin (IL)-8, IL-1β, and interferon-gamma (IFN-γ) in both children and adults with obstructive sleep apnea (OSA) in comparison to controls. Methods: Four electronic databases were systematically searched (PubMed, Web of Science, Scopus, and Cochrane Library) through 19 October 2023, without any restrictions on language, date, age, and sex. We used Review Manager version 5.3 to perform meta-analysis and presented the data as standardized mean difference (SMD) and 95% confidence interval (CI) values to evaluate the relationships between the levels of cytokines and OSA. Results: A total of 102 articles (150 independent studies) were included in the meta-analysis. The pooled SMDs in adults were 1.42 (95%CI: 1.11, 1.73; p < 0.00001), 0.85 (95%CI: 0.40, 1.31; p = 0.0002), 0.69 (95%CI: 0.22, 1.16; p = 0.004), and 0.39 (95%CI: -0.37, 1.16; p = 0.31) for TNF-α, IL-8, IL-1β, and IFN-γ, respectively. The pooled SMDs in children were 0.84 (95%CI: 0.35, 1.33; p = 0.0008), 0.60 (95%CI: 0.46, 0.74; p < 0.00001), 0.25 (95%CI: -0.44, 0.93; p = 0.49), and 3.70 (95%CI: 0.75, 6.65; p = 0.01) for TNF-α, IL-8, IL-1β, and IFN-γ, respectively. Conclusions: The levels of proinflammatory cytokines of TNF-α, IL-8, and IL-1β in adults, and TNF-α, IL-8, and IFN-γ in children with OSA, are significantly higher than those in controls.

MEASURE: Multiplex Exhaled Breath Condensate - Scanning Using Rapid Electro-Analytics

Exhaled breath condensate is an emerging source of inflammatory biomarkers suitable for the noninvasive detection of respiratory disorders. Current gold standard methods are highly invasive and pose challenges in sample collection during airway inflammation monitoring. Cytokine biomarkers are detectable in EBC at increased or decreased concentrations. IL-6, IL-1β, IL-8, and hs-CRP are characteristic biomarkers identified in respiratory disorders. We have demonstrated the promising outcomes of a 16-plexed electrochemical platform - READ 2.0 for the multiplexed detection of characteristic biomarkers in EBC. The sensor demonstrates dynamic ranges of 1-243 pg/mL with a lower detection limit of 1 pg/mL for IL-6 and IL-1β, while the detection range and limit of detection for IL-8 and hs-CRP is 1-150 pg/mL and 3 pg/mL, respectively. The detection accuracies for the biomarkers are in the range of ∼85 ± 15% to ∼100 ± 10%. The sensor shows a nonspecific response to similar cross-reacting biomarkers. Analytical validation of the sensor with ELISA as the standard reference generated a correlation of R2 > 0.96 and mean biases of 10.9, 3.5, 17.4, and 3.9 pg/mL between the two methods for IL-6, IL-1β, IL-8, and hs-CRP, respectively. The precision of the sensor in detecting low biomarker concentrations yields a %CV of <7%. The variation in the sensor's response on repeat EBC sample measurements and within a 6 h duration is less than 10%. The READ 2.0 platform shows a promise that EBC-based biomarker detection can prove to be vital in predicting the severity and survival rates of respiratory disorders and serve as a reference point for monitoring EBC-based biomarkers.

A narrative review: CXC chemokines influence immune surveillance in obesity and obesity-related diseases: Type 2 diabetes and nonalcoholic fatty liver disease

Adipose tissue develops lipids, aberrant adipokines, chemokines, and pro-inflammatory cytokines as a consequence of the low-grade systemic inflammation that characterizes obesity. This low-grade systemic inflammation can lead to insulin resistance (IR) and metabolic complications, such as type 2 diabetes (T2D) and nonalcoholic fatty liver disease (NAFLD). Although the CXC chemokines consists of numerous regulators of inflammation, cellular function, and cellular migration, it is still unknown that how CXC chemokines and chemokine receptors contribute to the development of metabolic diseases (such as T2D and NAFLD) during obesity. In light of recent research, the objective of this review is to provide an update on the linkage between the CXC chemokine, obesity, and obesity-related metabolic diseases (T2D and NAFLD). We explore the differential migratory and immunomodulatory potential of CXC chemokines and their mechanisms of action to better understand their role in clinical and laboratory contexts. Besides that, because CXC chemokine profiling is strongly linked to leukocyte recruitment, macrophage recruitment, and immunomodulatory potential, we hypothesize that it could be used to predict the therapeutic potential for obesity and obesity-related diseases (T2D and NAFLD).

Effect of Obesity on the Expression of Genes Associated with Severe Asthma-A Pilot Study

Asthma is a complex condition resulting from the interaction of genes and environment. Obesity is a risk factor to develop asthma and contributes to poor response to asthma therapy and severity. The aim of the study was to evaluate the effect of obesity on the expression levels of genes previously associated with severe asthma. Three groups of subjects were studied: non-obese asthmatics (NOA), obese asthma patients (OA), and non-asthmatic obese subjects (O). Previously reported overexpressed (IL-10, MSR1, PHLDA1, SERPINB2, and CD86) and underexpressed genes (CHI3L1, CPA3, IL-8, and PI3) in severe asthma were analyzed by RT-qPCR in peripheral blood mononuclear cells (PBMCs). In the overexpressed genes, obesity significantly decreased the expression of MSR1 and PHLDA1 and had no effects on CD86, IL-10, and SERPINB2. In underexpressed genes, obesity did not affect PI3, CHI3L1, and IL-8 and significantly reduced CPA3 expression. The results of this study show that obesity should be included among the known factors that can contribute toward modifying the expression of genes associated with asthma and, in particular, severe asthma.

Autoantibodies of inflammatory cytokines as serum biomarkers in OSA patients

As many as 90% of patients with obstructive sleep apnea (OSA) may be undiagnosed. It is necessary to explore the potential value of autoantibodies against CRP, IL-6, IL-8 and TNF-α in the diagnosis of OSA. ELISA was performed to detect the level of autoantibodies against CRP, IL-6, IL-8 and TNF-α in sera from 264 OSA patients and 231 normal controls (NCs). The expression level of autoantibodies against CRP, IL-6 and IL-8 in OSA were significantly higher than that in NC while the level of anti-TNF-α was lower in OSA than that in NC. The per SD increment of anti-CRP, anti-IL-6 and anti-IL-8 autoantibodies were significantly associated with a 430%, 100% and 31% higher risk for OSA, respectively. The AUC of anti-CRP was 0.808 (95% CI: 0.771-0.845) when comparing OSA with NC, while the AUC increased to 0.876 (95% CI: 0.846-0.906) combining four autoantibodies. For discrimination of severe OSA versus NC and non-severe OSA versus NC, the AUC for four autoantibodies combination was 0.885 (95% CI: 0.851-0.918) and 0.876 (95% CI: 0.842-0.913). This study revealed the association between autoantibodies against inflammatory factors and OSA, and the combination of autoantibodies against CRP, IL-6, IL-8 and TNF-α may function as novel biomarker for monitoring the presence of OSA.

Adipocytokines in obstructive sleep apnea: A systematic review and meta-analysis

BACKGROUND AND AIM

Adipocytokines play an important role in obstructive sleep apnea (OSA) by mediating inflammatory responses. Previous studies have reported that OSA is related to a change in the serum levels of adipocytokines; however, the results are still controversial. This meta-analysis aimed to assess the relationship between OSA and circulating level of adipocytokines in adults and children.

METHODS

A comprehensive search was conducted in databases of Medline/PubMed and Scopus for pertinent articles published since their inception to July 2022. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) were used to assess the strength of the relationship between the concentrations of adipocytokines with OSA.

RESULTS

In the overall analysis, contrary to IL-10, which showed a significant reduction, IL-1β, IL-4, IL-8, IL-17, and IFN- gamma showed higher levels in OSA patients in comparison with control groups (p <0.05). For adults, IL-1β, IL-8, IL-17, IL-18, vaspin, visfatin, and chemerin were linked to a greater serum levels in patients with OSA, while, IL-5 and IL-10 were detected significantly lower in adults with OSA in comparison with healthy adults (p <0.05). In children with OSA, the serum levels of IL-4, IL-8, IL-12, IL-17, IL-23, and IFN-gamma were significantly higher than healthy children (p <0.05).

CONCLUSION

The levels of inflammatory markers were found to be higher in OSA patients compared with control individuals, suggesting that adipocytokines may contribute to the pathology of OSA.

Evaluation of Blood Intercellular Adhesion Molecule-1 (ICAM-1) Level in Obstructive Sleep Apnea: A Systematic Review and Meta-Analysis

Background and objective: Intercellular adhesion molecule-1 (ICAM-1) appears to be an active and important biomarker for decreasing the risk of cardiovascular issues among individuals with obstructive sleep apnea (OSA). Herein, a systematic review and meta-analysis was designed to probe whether plasma/serum ICAM-1levels are different in adults with OSA compared to adults with no OSA, as well as adults with severe OSA compared to adults with mild/moderate OSA. Materials and methods: A thorough and systematic literature search was performed in four databases (PubMed/Medline, Web of Science, Scopus, and Cochrane Library) until 17 July 2022, without any age and sample size restrictions to retrieve the relevant articles. The standardized mean difference (SMD) along with a 95% confidence interval (CI) of plasma/serum of ICAM-1 levels was reported. Analyses, including sensitivity analysis, subgroup analysis, trial sequential analysis, meta-regression, and a funnel plot analysis, were performed in the pooled analysis. Results: A total of 414 records were identified in the databases, and 17 articles including 22 studies were entered into the meta-analysis. The pooled SMD of serum/plasma ICAM-1 levels in adults with OSA compared to controls was 2.00 (95%CI: 1.41, 2.59; p < 0.00001). The pooled SMD of serum/plasma ICAM-1 levels in adults with severe compared to mild/moderate OSA was 3.62 (95%CI: 1.74, 5.51; p = 0.0002). Higher serum/plasma ICAM-1 levels were associated with a higher mean age of controls, higher scores for the apnea-hypopnea index, and with a lower mean age of adults with OSA and with smaller sample sizes. Conclusions: Th results of the present meta-analysis showed that serum/plasma ICAM-1 levels in adults with OSA was higher than serum/plasma ICAM-1 levels in controls. Similarly, serum/plasma ICAM-1 levels in adults with severe OSA were higher compared to serum/plasma ICAM-1 levels of adults with mild or moderate OSA. Therefore, ICAM-1 may be used as an additional diagnostic and therapeutic biomarker in adults with OSA.

Associations between sleep, obesity, and asthma in urban minority children

STUDY OBJECTIVES

Although obesity, asthma, and sleep-disordered breathing are interrelated, there is limited understanding of the independent contributions of body-mass index and pulmonary function on polysomnography in children with asthma.

METHODS

We conducted a retrospective chart review on 448 7- to 18-year-old children with asthma who had undergone polysomnography testing between 1/2007-12/2011 to elucidate the association between spirometry variables, body-mass index, and polysomnography parameters, adjusting for asthma and antiallergic medications.

RESULTS

Obese children had poorer sleep architecture and more severe gas exchange abnormalities compared to healthy weight children. Multivariate analysis revealed an independent association of body-mass index with sleep efficiency, with more light and less deep sleep in both obese and healthy-weight children, and with baseline oxygen saturation and oxygen nadir in obese children. In obese children, forced vital capacity was independently associated with less deep sleep (time in N3 sleep) as well as with oxygen nadir, while among healthy-weight children, forced expiratory volume directly correlated but forced vital capacity inversely correlated with deep sleep. In obese children, inhaled corticosteroid was associated with baseline oxygen saturation, and montelukast was associated with lower end-tidal carbon dioxide. In healthy-weight children, inhaled corticosteroid was associated with arousal awakening index, and montelukast was associated with light sleep. Antiallergic medications were not independently associated with polysomnography parameters.

CONCLUSIONS

Pulmonary function, body-mass index, and asthma medications have independent and differing influences on sleep architecture and gas exchange polysomnography parameters in obese and healthy-weight children with asthma. Asthma medications are associated with improved gas exchange in obese children and improved sleep architecture in healthy-weight children with asthma.

CITATION

Conrad LA, Nandalike K, Rani S, Rastogi D. Associations between sleep, obesity, and asthma in urban minority children. J Clin Sleep Med. 2022;18(10):2377-2385.

Inflammatory Biomarkers in Exhaled Breath Condensate: A Systematic Review

Inflammation is a comprehensive set of physiological processes that an organism undertakes in response to a wide variety of foreign stimuli, such as viruses, bacteria, and inorganic particles. A key role is played by cytokines, protein-based chemical mediators produced by a broad range of cells, including the immune cells recruited in the inflammation site. The aim of this systematic review is to compare baseline values of pro/anti-inflammatory biomarkers measured in Exhaled Breath Condensate (EBC) in healthy, non-smoking adults to provide a summary of the concentrations reported in the literature. We focused on: interleukin (IL)-1β, IL-4, IL-6, IL-8, IL-10, tumour necrosis factor-alpha (TNF-α), and C reactive protein (CRP). Eligible articles were identified in PubMed, Embase, and Cochrane CENTRAL. Due to the wide differences in methodologies employed in the included articles concerning EBC sampling, storage, and analyses, research protocols were assessed specifically to test their adherence to the ATS/ERS Task Force guidelines on EBC. The development of reference intervals for these biomarkers can result in their introduction and use in both research and clinical settings, not only for monitoring purposes but also, in the perspective of future longitudinal studies, as predictive parameters for the onset and development of chronic diseases with inflammatory aetiology.

Risk factors for SARS-CoV-2 infection and transmission in households with children with asthma and allergy: A prospective surveillance study

BACKGROUND

Whether children and people with asthma and allergic diseases are at increased risk for severe acute respiratory syndrome virus 2 (SARS-CoV-2) infection is unknown.

OBJECTIVE

Our aims were to determine the incidence of SARS-CoV-2 infection in households with children and to also determine whether self-reported asthma and/or other allergic diseases are associated with infection and household transmission.

METHODS

For 6 months, biweekly nasal swabs and weekly surveys were conducted within 1394 households (N = 4142 participants) to identify incident SARS-CoV-2 infections from May 2020 to February 2021, which was the pandemic period largely before a vaccine and before the emergence of SARS-CoV-2 variants. Participant and household infection and household transmission probabilities were calculated by using time-to-event analyses, and factors associated with infection and transmission risk were determined by using regression analyses.

RESULTS

In all, 147 households (261 participants) tested positive for SARS-CoV-2. The household SARS-CoV-2 infection probability was 25.8%; the participant infection probability was similar for children (14.0% [95% CI = 8.0%-19.6%]), teenagers (12.1% [95% CI = 8.2%-15.9%]), and adults (14.0% [95% CI = 9.5%-18.4%]). Infections were symptomatic in 24.5% of children, 41.2% of teenagers, and 62.5% of adults. Self-reported doctor-diagnosed asthma was not a risk factor for infection (adjusted hazard ratio [aHR] = 1.04 [95% CI = 0.73-1.46]), nor was upper respiratory allergy or eczema. Self-reported doctor-diagnosed food allergy was associated with lower infection risk (aHR = 0.50 [95% CI = 0.32-0.81]); higher body mass index was associated with increased infection risk (aHR per 10-point increase = 1.09 [95% CI = 1.03-1.15]). The household secondary attack rate was 57.7%. Asthma was not associated with household transmission, but transmission was lower in households with food allergy (adjusted odds ratio = 0.43 [95% CI = 0.19-0.96]; P = .04).

CONCLUSION

Asthma does not increase the risk of SARS-CoV-2 infection. Food allergy is associated with lower infection risk, whereas body mass index is associated with increased infection risk. Understanding how these factors modify infection risk may offer new avenues for preventing infection.

Examining the Relationship Between Diabetic Macular Edema, and Obstructive Sleep Apnea

Purpose

This prospective cohort study examined the relationship between diabetic macular edema (DME), diabetic retinopathy (DR) and obstructive sleep apnea (OSA) in patients after 1 year of treatment with anti-VEGF injection and/or continuous positive airway pressure (CPAP).

Patients and Methods

The study included adults with type 1 or 2 diabetes mellitus with diabetic retinopathy. Polysomnography metrics were measured at baseline. Ophthalmologic metrics were measured at baseline, six-month (6m) and twelve-month (12m) follow-up. All DME+ patients received standard care, and all OSA+ patients were advised continuous positive airway pressure (CPAP). Logistic regression between DR severity and OSA severity was performed. Analysis of variance (ANOVA) was performed between subgroups.

Results

Seventy-four eyes of 49 patients with DR were included. Prevalence of OSA was significantly higher in the DME+ group (70.7%) than DME- group (42.4%, p < 0.05). A significantly lower average minimum SaO₂ was noted in OSA+DME+ (81.74%) than OSA+DME- eyes (88.23%, p < 0.05). Logistic regression analysis of ophthalmological and sleep metrics showed no correlation between DR and OSA severity. CPAP adherence was 20% (6/30) in the OSA+DME+ cohort and 36% (5/14) in the OSA+DME- cohort. At 12m, CPAP-adherent OSA+DME+ showed significantly lower DR severity score (1.00 ± 0.0) than CPAP non-adherent OSA+DME+ (1.36 ± 0.80, p = 0.042). No significant patterns were noted for visual acuity and mean central retinal thickness.

Conclusion

DME is associated with the presence of OSA. Minimum SaO₂ is a significant OSA clinical variable for DME. DR severity is not associated with OSA severity. CPAP coupled with intravitreal anti-VEGF therapy may be helpful for reducing DR severity in DME+ eyes. Presence of OSA may diminish intravitreal anti-VEGF efficacy on anatomical (mean CRT) and functional (VA) outcomes of DME.

Molecular signalling involved in upper airway remodelling is enhanced in patients with obstructive sleep apnoea

Objective

This study aimed to elucidate whether molecular signalling involved in upper airway remodelling is enhanced in patients with obstructive sleep apnoea.

Method

Twenty patients with mild obstructive sleep apnoea (control group) and 40 patients with moderate to severe obstructive sleep apnoea (obstructive sleep apnoea group) who desired uvulopalatopharyngoplasty were recruited for the study. After uvulopalatopharyngoplasty, surgical specimens of the uvula were subjected to haematoxylin and eosin, Masson's trichrome and immunohistochemical staining. Western blot and reverse transcriptase-polymerase chain reaction were used to evaluate the protein and messenger RNA expressions.

Results

The obstructive sleep apnoea group showed more severe inflammation, increased collagen deposition and higher immunohistochemical staining intensity for TGF-ß and MMP-9 as well as higher protein and messenger RNA expression of MMP-9, VEGF, TGF-ß, p38 MAPK, SMAD 2/3, AKT and JNK in the uvula than control group.

Conclusion

Patients with obstructive sleep apnoea demonstrated more severe inflammation, increased airway remodelling, and increased protein and messenger RNA expression of pro-inflammatory and pro-fibrotic cytokines in the uvula than control participants.

Current and future strategies for diagnostic and management of obstructive sleep apnea

INTRODUCTION

Obstructive sleep apnea (OSA) is a common sleep disorder with multiple comorbidities including hypertension, diabetes, and cardiovascular disorders. Detected based on an overnight sleep study is called polysomnography (PSG); OSA still remains undiagnosed in majority of the population mainly attributed to lack of awareness. To overcome the limitations posed by PSG such as patient discomfort and overnight hospitalization, newer technologies are being explored. In addition, challenges associated with current management of OSA using continuous positive airway pressure (CPAP), etc. presents several pitfalls.

AREAS COVERED

Conventional and modern detection/management techniques including PSG, CPAP, smart wearable/pillows, bio-motion sensors, etc., have both pros and cons. To fulfill the limitations in OSA diagnostics, there is an imperative need for new technology for screening of symptomatic and more importantly asymptomatic OSA patients to reduce the risk of several associated life-threatening comorbidities. In this line, molecular marker-based diagnostics have shown great promises.

EXPERT OPINION

A detailed overview is presented on the OSA management and diagnostic approaches and recent advances in the molecular screening methods. The potentials of biomarker-based detection and its limitations are also portrayed and a comparison between the standard, current modern approaches, and promising futuristic technologies for OSA diagnostics and management is set forth.ABBREVIATIONS AHI: Apnea hypopnea index; AI: artificial intelligence; CAM: Cell adhesion molecules; CPAP: Continuous Positive Airway Pressure; COVID-19: Coronavirus Disease 2019; CVD: Cardiovascular disease; ELISA: Enzyme linked immunosorbent assay; HSAT: Home sleep apnea testing; IR-UWB: Impulse radio-ultra wideband; MMA: maxillomandibular advancement; PSG: Polysomnography; OSA: Obstructive sleep apnea; SOD: Superoxide dismutase; QD: Quantum dot.

Interleukin-8 concentrations in obstructive sleep apnea syndrome: a systematic review and meta-analysis

Interleukin (IL)-8 has been shown to play an important role in obstructive sleep apnea syndrome (OSAS). However, its role in OSAS development is still controversial. This meta-analysis was to explore the correlation between interleukin (IL)-8 concentration and OSAS. Database (from the inception to July 2021) searches on PubMed, Web of Science, Medline, EMBASE, and Cochrane Library were conducted for studies analyzing the correlation between IL-8 concentration and OSAS, regardless of the language of publication. Standardized mean difference (SMD) and 95% confidence intervals (CI) were used to analyze any prospective association between IL-8 concentration and OSAS. A total of 25 eligible studies, including 2301 participants and 1123 controls, were included in this meta-analysis. The included studies evaluating the association between serum IL-8 concentration and OSAS indicated that adults and children with OSAS had elevated serum concentrations of IL-8 compared with controls (SMD = 0.997, 95% CI = 0.437–1.517, P < 0.001; SMD = 0.431, 95% CI = 0.104–0.759, P = 0.01). Categorization of the study population into subgroups according to body mass index, apnea–hypopnea index (AHI), ethnicity, and sample size also showed that individuals with OSAS had elevated serum concentrations of IL-8 compared with controls. Additionally, the results demonstrated that the higher the AHI, higher was the IL-8 concentration. Similar results were observed in the literature on the association between plasma IL-8 concentration and OSAS. This meta-analysis verified that compared with controls, children and adults with OSAS have significantly elevated IL-8 concentrations.

Elevated Monocytic Interleukin-8 Expression under Intermittent Hypoxia Condition and in Obstructive Sleep Apnea Patients

Obstructive sleep apnea (OSA) is a disease with great cardiovascular risk. Interleukin-8 (IL-8), an important chemokine for monocyte chemotactic migration, was studied under intermittent hypoxia condition and in OSA patients. Monocytic THP-1 cells were used to investigate the effect of intermittent hypoxia on the regulation of IL-8 by an intermittent hypoxic culture system. The secreted protein and mRNA levels were studied by means of enzyme-linked immunosorbent assay and RT/real-time PCR. The chemotactic migration of monocytes toward a conditioned medium containing IL-8 was performed by means of the transwell filter migration assay. Peripheral venous blood was collected from 31 adult OSA patients and RNA was extracted from the monocytes for the analysis of IL-8 expression. The result revealed that intermittent hypoxia enhanced the monocytic THP-1 cells to actively express IL-8 at both the secreted protein and mRNA levels, which subsequently increased the migration ability of monocytes toward IL-8. The ERK, PI3K and PKC pathways were demonstrated to contribute to the activation of IL-8 expression by intermittent hypoxia. In addition, increased monocytic IL-8 expression was found in OSA patients, with disease severity dependence and diurnal changes. This study concluded the monocytic IL-8 gene expression can be activated by intermittent hypoxia and increased in OSA patients.

Circulating levels of cell adhesion molecules and risk of cardiovascular events in obstructive sleep apnea

Background

Obstructive sleep apnea (OSA) patients are at increased risk of cardiovascular disease (CVD). Cell adhesion molecules (CAM) are increased in OSA and CAM are also implicated in the development of CVD.

Research question

Do CAM (ICAM-1, VCAM-1 and E-selectin) have prognostic value in identifying risk of cardiovascular events in OSA?

Study design and methods

Patients with suspected OSA referred for a polysomnogram provided a fasting blood sample. Plasma levels of ICAM-1, VCAM-1 and E-selectin were determined by multiplex Luminex Assay (Milliporesigma ON, Canada). Cardiovascular events were determined by deterministic linkage to provincial health databases.

Results

418 patients were included in the analysis. Mostly male (68.2%), mean age of 50.7 yrs, median AHI 16.5 events/hour, and mean BMI of 31.7 kg/m². 36 cardiovascular events occurred in 8-yrs of follow up. Higher levels of ICAM-1 were associated with developing CVD (HR = 3.65 95% CI 1.40–9.53, 2^nd and 3rd tertiles vs. 1^st tertile), including in patients with OSA (HR = 3.1 95% CI 1.16–8.25). E-selectin was significantly associated with cardiovascular events in patients with moderate to severe OSA (HR = 3.31 95% CI 0.94–11.72, 2^nd and 3^rd tertiles vs. 1^st tertile) but not in patients without moderate to severe OSA (HR = 0.67 95% CI 0.19–2.38), p-value for interaction = 0.07.

Interpretation

In a suspected OSA cohort, patients with higher levels of ICAM-1 (>816 ng/ml) were significantly more likely to experience a cardiovascular event within 8 years after PSG. In moderate to severe OSA patients, a higher E-selectin (>36.4 ng/ml) was significantly associated with cardiovascular events.

Increased levels of VCAM-1 is associated with higher occurrence of coronary artery disease in adults with moderate to severe obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) leads to important vascular abnormalities, including the endothelial dysfunction and the production of endothelial cell adhesion molecules. The adhesion molecules play an important role in the process of endothelial dysfunction in the pathogenesis of atherosclerosis. We assess the relationship between the levels of adhesion molecules and the presence of coronary artery disease (CAD) in Chinese adults with moderate to severe OSA.

METHODS

The cross-sectional study included a total of 189 Chinese adults: 90 patients with moderate to severe OSA (apnea-hypopnea index≥15 events/h) alone, 40 patients with moderate to severe OSA and CAD, and 59 controls without OSA or with mild OSA and without CAD. We used high-throughput Multiplex Immunobead Assay technology to simultaneously test plasma levels of vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1). The associations between the levels of circulating adhesion molecules and CAD in moderate to severe OSA patients were evaluated by multivariate logistic regression analysis.

RESULTS

The circulating VCAM-1 levels were significantly elevated in patients suffering from moderate to severe OSA combined CAD compared with patients having moderate to severe OSA alone [853.28 (564.26) vs. 416.61 (301.69) ng/mL, P < 0.001]. Furthermore, circulating VCAM-1 levels were independently associated with CAD (odds ration = 2.113, 95%CI 1.400-2.766, P < 0.001) and showed higher discriminatory accuracy in assessing the presence of CAD (AUC: 0.899, 95%CI 0.849-0.950, P < 0.001) in moderate to severe OSA patients. However, no significant association was found between circulating ICAM-1 levels and CAD in moderate to severe OSA patients.

CONCLUSIONS

The circulating VCAM-1 levels were significantly correlated with the presence of CAD in Chinese adults with moderate to severe OSA. The circulating VCAM-1 may function as a novel biomarker for monitoring the development and progression of CAD in patients with moderate to severe OSA.

Relation between IL-8 level and obstructive sleep apnea syndrome

Objective

This meta-analysis was conducted to explore the relationship between serum level of IL-8 and obstructive sleep apnea syndrome (OSAS).

Methods

Electronic databases were retrieved according to the inclusion and exclusion criteria, relevant studies exploring the relationship between serum level of IL-8 and OSAS were enrolled. Statistical analysis was performed using STATA 12.0.

Results

Totally 199 studies were retrieved, among which 10 were qualified for the inclusion criteria and were finally included in the meta-analysis with 367 cases of OSAS patients and 335 control cases. Serum level of IL-8 was higher in patients than healthy controls (Standard mean difference (SMD) = 2.16, 95% CI = 1.17–3.15, P < 0.001). The subgroup analysis based on ethnicity revealed that average serum level of IL-8 were higher in Asian and Caucasian OSAS patients than healthy controls (Asian: SMD = 2.50, 95% CI = 1.13–3.87, P < 0.001; Caucasian: SMD = 1.59, 95% CI = 0.11–3.06, P = 0.035). Further subgroup analysis based on age indicated a statistical difference in serum level of IL-8 between adult OSAS patients and healthy counterparts (SMD = 2.73, 95% CI = 1.49–3.98, P < 0.001).

Conclusion

The level of IL-8 was related to OSAS in adult patients, and increased serum IL-8 level may increase the risk of OSAS.

New frontiers in pharmacologic obstructive sleep apnea treatment: A narrative review

Obstructive sleep apnea (OSA) is the most common form of sleep-disordered breathing characterized by intermittent partial or complete closure of the upper airway during sleep. If left untreated, OSA is associated with adverse cardiovascular outcomes such as hypertension, coronary heart disease, heart failure, cardiac arrhythmia, stroke, and death. Positive airway pressure (PAP) is often considered the first-line treatment for OSA. While PAP can be very effective in reducing the number of obstructive apneas and hypopneas, its impact on prevention of adverse cardiovascular consequences remains controversial, and treatment adherence is often poor. Hence, the necessity for novel treatment options to help those who cannot adhere to positive airway pressure treatment. Different classes of medications have been tested with regards to their effect on OSA severity. This review 1) provides an update on the epidemiology and pathophysiology of OSA, 2) outlines the mechanistic rationale for medication classes tested as OSA treatment and 3) discusses the effects of these medications on OSA. Several wake-promoting medications are approved for management of persistent sleepiness despite OSA treatment; discussion of these symptomatic treatments is outside the scope of this review. Herein, the authors review the current evidence for pharmacological management of OSA and provide future directions.

Role of interleukin 8 in depression and other psychiatric disorders

Low grade neuroinflammation has been suggested as one of the underlying mechanisms of many psychiatric diseases as well as cognitive disorders. Interleukin 8 (IL-8), a proinflammatory cytokine produced by many cell types including macrophage and microglia, mainly functions as a neutrophil chemoattractant in the bloodstream. IL-8 is also found in the brain, where it is released from microglia in response to proinflammatory stimuli. In this review, we highlight studies focusing on the role of IL-8 in psychiatric diseases such as major depression, bipolar disorder, schizophrenia, sleep disorder, autism spectrum disorder, anxiety disorders and dementia. Increased peripheral IL-8 levels have been reported in these diseases, particularly in schizophrenic disorder, bipolar disorder, obstructive sleep apnea and autism spectrum disorder. The literature on IL-8 and major depression is inconsistent. IL-8 has been found to be a factor associated with schizophrenic prognosis and therapeutic response, and may affect a wide range of symptomatology. Considering that the exact role of immune alterations is still under research, the success of immune-based therapies in psychiatric diseases is limited for the time being.

Effect of obstructive sleep apnea on immunity in cases of chronic rhinosinusitis with nasal polyp

Objective

Chronic rhinosinusitis (CRS) with nasal polyp (wNP) is a more severe inflammatory form of CRS that often coexists with obstructive sleep apnea (OSA). However, little is known the relationship between OSA and immunologic profile on patients with CRSwNP. We aimed to investigate the immune profile of patients with CRSwNP according to OSA severity.

Methods

This study included 63 patients with CRSwNP and nine control subjects. Protein levels of inflammatory mediators were determined using multiplex immunoassay. All patients underwent standard polysomnography.

Results

We found that, in patients with eosinophilic CRSwNP (ECRSwNP), IL-6 and CXCL-1 (type 1 immune-related markers) were upregulated in cases of moderate-to-severe OSA. Additionally, IL-4, IL-13, CCL-11, CCL-24 (type 2 immune-related markers), and IL-17A (type 3 immune-related marker) were increased in patients with moderate-to-severe OSA. Though there were no significant differences in type 1, 2, or 3 immune-related markers among patients with non-eosinophilic CRSwNP (NECRSwNP) according to the severity of OSA, TGF--β expression was increased in those with moderate-to-severe OSA. Furthermore, in ECRSwNP with moderate-to-severe OSA, associations were detected between serum markers and some upregulated inflammatory markers.

Conclusion

Our findings revealed that OSA may increase the heterogeneity of immune profiles (types 1, 2, and 3) in patients with ECRSwNP but not in those with NECRSwNP.

Exhaled breath analysis in disease detection

Investigating the use of exhaled breath analysis to diagnose and monitor different diseases has attracted much interest in recent years. This review introduces conventionally used methods and some emerging technologies aimed at breath analysis and their relevance to lung disease, airway inflammation, gastrointestinal disorders, metabolic disorders and kidney diseases. One section correlates breath components and specific diseases, whereas the other discusses some unique ideas, strategies, and devices to analyze exhaled breath for the diagnosis of some common diseases. This review aims to briefly introduce the potential application of exhaled breath analysis for the diagnosis and screening of various diseases, thereby providing a new avenue for the detection of non-invasive diseases.

The effects of intermittent hypoxia on human nasal mucosa

Purpose

Intermittent hypoxia (IH) is characterized by hypoxia-reoxygenation, reported to be a critical risk factor for obstructive sleep apnea (OSA). This experiment aimed to evaluate the direct effects of IH on the human nasal mucosa.

Methods

The direct effects of IH on the human nasal mucosa was evaluated by measuring the ciliary beat frequency (CBF) and expression levels of inflammatory cytokines (granulocyte-macrophage colony-stimulating factor, transforming growth factor-β, interleukin-6, and tumor necrosis factor-α). The normoxia group was exposed to a normoxic condition for 72 h. The IH group was exposed to 288 cycles of IH (1 cycle: hypoxia, 5 min; subsequent normoxia, 10 min) for 72 h. CBF was measured using an automated computer-based video image processing technique. Changes in the expression of cytokines were assessed by real-time reverse transcription-polymerase chain reaction (RT-PCR).

Results

The normoxia group revealed a persistent CBF pattern and a physiological range of inflammatory cytokines. However, the IH group showed a cyclic decrease in CBF and increased expression of inflammatory cytokines. Cytotoxicity assay indicated no difference in the survival rates between the two groups.

Conclusions

IH results in increased expression of inflammatory cytokines that adversely affects the mucociliary transport in the upper airway and, consequently, may result in airway inflammation.

Dimethyl Fumarate and Its Esters: A Drug with Broad Clinical Utility?

Fumaric acid esters (FAEs) are small molecules with anti-oxidative, anti-inflammatory and immune-modulating effects. Dimethyl fumarate (DMF) is the best characterised FAE and is approved and registered for the treatment of psoriasis and Relapsing-Remitting Multiple Sclerosis (RRMS). Psoriasis and RRMS share an immune-mediated aetiology, driven by severe inflammation and oxidative stress. DMF, as well as monomethyl fumarate and diroximel fumarate, are commonly prescribed first-line agents with favourable safety and efficacy profiles. The potential benefits of FAEs against other diseases that appear pathogenically different but share the pathologies of oxidative stress and inflammation are currently investigated.

Gene expression of the immunoinflammatory and immunological status of obese dogs before and after weight loss

Obesity is characterized by a low degree of chronic inflammation state that, along with metabolic modifications, promotes important changes in the animal's organism. Adipose tissue actively participates in inflammation and immunity, and several defense cells of the organism may, therefore, be involved in the diversity found between obese and ideal weight individuals. Studies regarding this subject have shown immune cell changes in humans and rats, however, the literature is scarce in relation to dogs. Thus, the present study aimed to evaluate the gene expression profile of immunoinflammatory response and the lymphoproliferation of obese dogs before and after weight loss. Eight female dogs, neutered, of different breeds, aged between 1 and 8 years (4.74±3.19), obese, with body condition score (BCS) of 9 out of a 9-point scale and body composition determined by the deuterium isotope dilution method were included. The obese dogs were enrolled in a weight loss program and after losing 20% of their initial weight became a second experimental group. A third experimental group consisted of eight female dogs, neutered, aged between 1 and 8 years (3.11±0.78) and with ideal BCS (5 out of a 9-point scale). Gene expression of immunoinflammatory cytokines (resistin, leptin, adiponectin, TNF-α, IL-6, IL-8, and IL-10) was assessed by qRT-PCR and immunity was assessed by lymphoproliferative response using the flow cytometry technique. The data that presented normal distribution was evaluated by analysis of variance by the PROC MIXED of the SAS and when differences were detected, these were compared by the Tukey test. Regarding the gene expression data, the procedure PROC GLIMMIX was adopted and the methodology of generalized linear model was used, in which the Gama distribution proved to be adequate. Values of p<0.05 were considered significant. The mean weight loss period of the animals included in the study was 194.25 ± 28.31 days and the mean weekly weight loss rate was 1.02 ± 0.82%. The average fat mass, both in percentage (P<0.001) and in kilograms (P = 0.012), was higher in the obese group (40.88%; 8.91kg), returning to normal and without difference between the control group (19.16%; 3.01kg) and after weight loss (22.10%; 4.11kg). The weight loss program resulted in an increase in percentage of lean body mass (P = 0.001), 55.50% in obese animals vs 77.90% in obese dogs after weight loss, the latter with no difference when compared to the control group (80.84%). The obese group presented increased gene expression of resistin and IL-8 in relation to the weight loss group (P = 0.002). In adiponectin, the obese group presented increased mRNA gene expression when compared to the weight loss group (P = 0.003). The evaluation of lymphocyte proliferation showed differences between the group of obese animals before and after weight loss (P = 0.004). Weight loss resulted in an increase in the lymphoproliferation rate (18.48%) compared to obese dogs at the beginning of the study (10.71%). These results indicate that weight loss modulates the immunoinflammatory response of obese dogs and may present important benefits to health and longevity of dogs.

The relationship between diurnal variation of cytokines and symptom expression in mild obstructive sleep apnea

OBJECTIVES

To identify the relationship between (1) cytokines and everyday symptoms and (2) cytokine diurnal variation and everyday symptoms in mild obstructive sleep apnea (OSA).

METHODS

An observational, single-night study of 20 adults with mild to moderate OSA undergoing diagnostic polysomnography. Everyday symptoms included sleepiness measured by Stanford Sleepiness Scale, fatigue and energy levels measured by Lee Fatigue Scale, and cytokine plasma concentrations including interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor-α (TNF-α) measured concurrent with symptoms at presleep (8 pm to 10 pm; time 1) and postsleep (5 am to 6 am; time. 2) Cytokine diurnal variation was calculated as [time 2 - time 1]. Wilcoxon signed-rank tests and Spearman partial rank correlations adjusted for age, body mass index, cardiovascular disease, and type 2 diabetes were used.

RESULTS

Twenty patients (50% male, obese, median age = 51.0 years) with mild OSA (apnea-hypopnea index, AHI; median 9.5 events/h) were evaluated. Evening IL-6 was associated with evening symptoms, including sleepiness (r = .69, P = .002) and energy level (r = -0.68, P = .003); morning IL-8 (r = .73, P = .001), and TNF-α (r = .59, P = .015) were associated with morning fatigue. Only morning IL-8 (r = -0.57, P = .022) and diurnal variations in IL-8 (r = -0.60, P = .014) were associated with morning energy level.

CONCLUSION

There is scant evidence addressing the diurnal variation of inflammatory biomarkers and the relationship with symptom expression in mild OSA. The present findings provide preliminary mechanistic findings for symptom expression in OSA and contribute insight to mild OSA symptom phenotypes.

Effects of continuous positive airway pressure on exhaled transforming growth factor-β and vascular endothelial growth factor in patients with obstructive sleep apnea

Background

Both transforming growth factor β (TGF-β) and vascular endothelial growth factor (VEGF) are master regulators of airway remodeling; however, their pathological roles in obstructive sleep apnea (OSA) remain unclear. The aim of the present study was to evaluate the expression of TGF-β and VEGF protein in the serum and exhaled breath condensate (EBC) before and after continuous positive airway pressure (CPAP) treatment in OSA patients.

Methods

Forty patients with moderate to severe OSA requiring CPAP and 20 healthy subjects were prospectively recruited. The concentrations of TGF-β and VEGF protein in the serum and EBC were evaluated by enzyme-linked immunosorbent assay. All OSA patients underwent a sleep study that was repeated 3 months after receiving CPAP therapy.

Results

Protein concentrations of TGF-β and VEGF in the serum did not differ between healthy controls and OSA patients before CPAP treatment. There was also no difference in the serum protein concentrations of TGF-β and VEGF of the OSA patients before and after CPAP treatment. However, both the TGF-β and VEGF protein concentrations in the EBC were higher in the OSA patients than those in control subjects, and recovered to normal levels after CPAP.

Conclusions

Successful treatment of OSA by CPAP can restore the TGF-β and VEGF protein concentrations in the EBC.

Does ischemia-modified albumin level predict severity of obstructive sleep apnea?

OBJECTIVE AND AIM

Ischemia-modified albumin (IMA) is a newly recognized marker of chronic inflammation used to evaluate oxidative stress status in patients with various diseases. We explored the possible relationship between IMA levels and obstructive sleep apnea (OSA).

METHODS

In this retrospective study, 169 of 216 sequential patients being evaluated for suspicion of OSAS met inclusion criteria. Polysomnography confirmed OSA in 86 patients (51%) while 81 patients (49%) without OSA were categorized as control subjects. All study participants were tested for blood IMA level, neutrophil/lymphocyte ratio (NLR), C-reactive protein (CRP) level, and red blood cell distribution width (RDW).

RESULTS

The serum IMA level was significantly higher in patients with OSAS than controls (p = 0.008). The serum IMA level increased significantly as OSAS severity increased (r = 0.50, p < 0.001) and was positively correlated with the AHI (r = 0.41, p < 0.001), CRP level (r = 0.31, p = 0.004), body mass index (r = 0.24, p = 0.022), RDW (r = 0.31, p = 0.03), oxygen desaturation index (ODI) (r = 0.22, p = 0.02), and negatively correlated with the hemoglobin concentration (r = - 0.28, p = 0.04) and minimum hemoglobin oxygen saturation (SpO2) (r = - 0.25, p = 0.02). Receiver operator curve (ROC) analysis showed that the optimal serum IMA, CRP, RDW, and NLR values were not different for predicting OSAS diagnosis (areas under the curves (AUC) = 0.62, 0.59, 0.60, and 0.43, respectively). However, the serum IMA level was superior in reflecting OSAS severity (AUC = 0.78) compared to CRP, RDW, and NLR values (AUC = 0.61, 0.53, and 0.51, respectively) (all p < 0.001).

CONCLUSION

Like other markers of inflammation, blood IMA levels were significantly elevated in patients with OSA. However, blood IMA level was a better predictor of disease severity than the other markers.

Olfactory Bulb Volume and Olfactory Sulcus Depth in Patients With OSA: An MRI Evaluation

OBJECTIVES

We evaluated olfactory functions in patients with obstructive sleep apnea (OSA).

METHODS

The cranial magnetic resonance images of 58 adult patients (36 males and 22 females) aged 27 to 79 years were retrieved from the hospital picture archiving and communication system (PACS) system. There were 29 patients with OSA (17 males and 12 females), diagnosed according to the polysomnography results. A control group consisted of 29 healthy patients without OSA. Olfactory bulb (OB) volume and olfactory sulcus (OS) depth measurements were performed. Nasal septal deviation (SD) was also evaluated and recorded as no SD, deviation to the right, and deviation to the left in all groups.

RESULTS

Olfactory bulb volumes of the OSA group were significantly lower than those of the control group (P < .05), whereas OS depth values were not different (P > .05). There was a positive correlation between the right and left OB volumes and right and left OS depth values (P < .05). In older patients with OSA and in female patients with OSA, OB volumes decreased bilaterally (P < .05). Olfactory sulcus depth of the right side was lower in the female patients with OSA compared to the male patients with OSA (P < .05). There were no significant correlations between apnea-hypopnea index and OB volumes and OS depth values in the OSA group (P > .05).

CONCLUSION

In patients with OSA, OB volumes decreased bilaterally. It may be related to intermittent nocturnal hypoxia/reoxygenation episodes, which may be a trigger for upper airway inflammation; and proinflammatory mediators maybe harmful on olfactory neuroepithelium and olfactory impairment may occur.

Exhaled Breath Analysis in Obstructive Sleep Apnea Syndrome: A Review of the Literature

Background and Objectives: Obstructive sleep apnea syndrome (OSAS) represents an independent risk factor for cardiovascular, metabolic and neurological events. Polysomnography is the gold-standard for the diagnosis, however is expensive and time-consuming and not suitable for widespread use. Breath analysis is an innovative, non-invasive technique, able to provide clinically relevant information about OSAS. This systematic review was aimed to outline available evidence on the role of exhaled breath analysis in OSAS, taking into account the techniques' level of adherence to the recently proposed technical standards. Materials and Methods: Articles reporting original data on exhaled breath analysis in OSAS were identified through a computerized and manual literature search and screened. Duplicate publications, case reports, case series, conference papers, expert opinions, comments, reviews and meta-analysis were excluded. Results: Fractional exhaled Nitric Oxide (FeNO) is higher in OSAS patients than controls, however its absolute value is within reported normal ranges. FeNO association with AHI is controversial, as well as its change after continuous positive airway pressure (C-PAP) therapy. Exhaled breath condensate (EBC) is acid in OSAS, cytokines and oxidative stress markers are elevated, they positively correlate with AHI and normalize after treatment. The analysis of volatile organic compounds (VOCs) by spectrometry or electronic nose is able to discriminate OSAS from healthy controls. The main technical issues regards the dilution of EBC and the lack of external validation in VOCs studies. Conclusions: Exhaled breath analysis has a promising role in the understanding of mechanisms underpinning OSAS and has demonstrated a clinical relevance in identifying individuals affected by the disease, in assessing the response to treatment and, potentially, to monitor patient's adherence to mechanical ventilation. Albeit the majority of the technical standards proposed by the ERS committee have been followed by existing papers, further work is needed to uniform the methodology.

A randomized, subject and rater-blinded, placebo-controlled trial of dimethyl fumarate for obstructive sleep apnea

Study Objectives

To investigate the therapeutic effect of dimethyl fumarate (DMF, an immunomodulatory agent) on obstructive sleep apnea (OSA), and potential influence of any such effect by selected proinflammatory molecules.

Methods

Patients with OSA who deferred positive airway pressure therapy were randomized (2:1) to receive DMF or placebo for 4 months. Participants underwent polysomnography before randomization and at 4 months. Blood was collected monthly. The primary outcome was the mean group change in respiratory disturbance index (δ-RDI). Secondary analyses focused on the association between treatment effect of DMF (on RDI) and expression of plasma cytokines and chemokines, or nuclear factor κ-B (NFκB) signaling molecules in peripheral blood mononuclear cells.

Results

N = 65 participants were randomized. N = 50 participants (DMF = 35, placebo = 15) had complete data for final analyses. The mean difference in δ-RDI between groups was 13.3 respiratory events/hour of sleep: -3.1+/-12.9 vs. 10.2+/-13.1 in DMF and placebo groups, respectively (mixed-effects model treatment effect: β = -0.14, SE = 0.062, p = 0.033). Plasma levels of TNF-α showed only nonsignificant decreases, and IL-10 and IL-13 only nonsignificant increases, in DMF-treated participants compared with placebo. No significant interaction or main effect on RDI for selected cytokines and chemokines was found. Participants with a therapeutic response to DMF did experience significant reductions in intracellular NFκB signaling molecules at 4 months. Overall, DMF was well-tolerated.

Conclusions

The immunomodulatory drug DMF partially ameliorates OSA severity. Suppression of systemic inflammation through reduction of NFκB signaling may mediate this effect.

Clinical Trials

ClinicalTrials.gov, NCT02438137, https://clinicaltrials.gov/ct2/show/NCT02438137?term=NCT02438137&rank=1.

Treatment of sleep apnea in patients with paroxysmal atrial fibrillation: design and rationale of a randomized controlled trial

RATIONALE

Atrial fibrillation is associated with increased mortality as well as morbidity. There is strong evidence for an association between atrial fibrillation and sleep apnea. It is not known whether treatment of sleep apnea with continuous positive airway pressure (CPAP) will reduce the burden of atrial fibrillation.

OBJECTIVE

The Treatment of Sleep Apnea in Patients with Paroxysmal Atrial Fibrillation study will investigate the effects of CPAP in patients with paroxysmal atrial fibrillation and sleep apnea.

DESIGN

The trial has a dual center, randomized, controlled, open-label, parallel design.

METHODS

Two centers will enroll a total of 100 patients with both paroxysmal atrial fibrillation and sleep apnea (apnea-hypopnea index [AHI] ≥ 15 events/h) who are scheduled for catheter ablation. Patients will be randomized in a 1:1 ratio to CPAP or control group (50 patients in each arm). The effects of CPAP treatment on atrial fibrillation will be determined using an implanted loop recorder (Reveal LINQ™, Medtronic) that detects all arrhythmia episodes. The primary endpoint is a reduction of the total burden of atrial fibrillation in the intervention group, after 5 months' follow-up (preablation). Reduction in the arrhythmia recurrence rate after ablation is the main secondary endpoint. All patients will be followed up for 12 months after ablation.

CONCLUSION

This study is the first randomized controlled trial that will provide data on the effects of CPAP therapy in patients with paroxysmal atrial fibrillation and sleep apnea. The results are expected to improve our understanding of the interaction between paroxysmal atrial fibrillation and sleep apnea. ClinicalTrials.gov Identifier. NCT02727192.

Measurement of fractional exhaled nitric oxide and nasal nitric oxide in male patients with obstructive sleep apnea

Objective

Airway inflammation plays an important role in obstructive sleep apnea (OSA); exhaled nitric oxide is regarded as a noninvasive marker of airway inflammation. The aim of this study was to evaluate fractional exhaled nitric oxide (FeNO) and nasal nitric oxide (nNO) in patients with OSA.

Methods

Seventy-five patients with OSA and 30 health controls were enrolled in this study. FeNO and nNO were measured before and after sleep. Nasal lavage was performed in 31 non-smoking individuals immediately after NO measurement in the morning. The sample of nasal lavage was taken for cell classification and analyzing interleukin 6 (IL-6) and interleukin 8 (IL-8).

Results

Both FeNO and nNO were significantly higher in OSA (before sleep FeNO 21.08 ± 8.79 ppb vs.16.90 ± 6.86 ppb, p = 0.022; after sleep FeNO 25.57 ± 15.58 ppb vs.18.07 ± 6.25 ppb, p = 0.003; before sleep nNO 487.03 ± 115.83 ppb vs. 413.37 ± 73.10 ppb, p = 0.001; after sleep nNO 550.07 ± 130.24 ppb vs. 460.43 ± 109.77 ppb, p < 0.001). Furthermore, in non-smoking OSA, nNO levels were positively correlated with apnea hypopnea index (AHI) and average decrease of pulse arterial oxygen saturation (SpO₂); after sleep, nNO was also positively associated to recording time with SpO₂ < 90% and negatively associated to minimum SpO₂. Both before and after sleep nNO levels were positively correlated with the percentage of neutrophils in nasal lavage (r = 0.528, p = 0.014; r = 0.702, p < 0.001, respectively). Additionally, before sleep nNO was also positively associated with IL-6 (r = 0.586, p = 0.005) and IL-8 (r = 0.520, p = 0.016) concentration.

Conclusion

This study sustains the presence of airway inflammation in OSA patients with the increase of FeNO and nNO. The data suggests nNO might have greater value than FeNO since it positively correlated with OSA severity, and nNO is a potential bio-marker of nasal inflammation in non-smoking OSA patients.

Electronic supplementary material

The online version of this article (10.1007/s11325-018-1760-1) contains supplementary material, which is available to authorized users.

The shifting relationship between weight and pediatric obstructive sleep apnea: A historical review

OBJECTIVES

For more than a century, pediatric obstructive sleep apnea (OSA) was associated with failure to thrive. However, that association has faded over the last few decades. A 21st century child with OSA is much more likely to be overweight than underweight. This raises the question: Has pediatric OSA changed over time, or has the rise of childhood obesity in the United States created a new, separate disease? This literature review explores the historical shift in the relationship between weight and OSA, and the associated changes in treatment.

RESULTS

We demonstrate a clear transition in the prevalence of failure to thrive and obesity in the OSA literature in the mid-2000s. What is less clear is whether these two clinical phenotypes should be considered two distinct diseases, or whether subtle differences in one set of pathophysiologic pathways-adenotonsillar hypertrophy, altered inflammation, and increased energy expenditure-can lead to divergent metabolic outcomes. More research is needed to fully elucidate the pathophysiology of OSA in children with obesity.

CONCLUSIONS

We may need new and different treatments for obesity-associated OSA as adenotonsillectomy-which is effective at reversing failure to thrive in OSA-is not as effective at treating OSA in children with obesity. One option is drug-induced sleep endoscopy, which could personalize and improve surgical treatment of OSA. There is some evidence that therapies used for OSA in adults (e.g., weight loss and positive airway pressure) are also helpful for overweight/obese children with OSA. Laryngoscope, 129:2414-2419, 2019.

Olfactory evaluation in obstructive sleep apnoea patients

The sense of smell has a high impact on the quality of life. The aim of the present study was to investigate olfactory dysfunction in patients with obstructive sleep apnoea syndrome (OSAS) and correlate the severity of disease with olfactory dysfunction. The relationships between nasal obstruction, nasal mucociliary cleareance and olfactory tests were also evaluated. Sixty patients with a diagnosis of OSAS were enrolled and underwent olfactory function evaluation. In all patients olfactory performance was tested with the Sniffin' Sticks method. Mucociliary transport times and anterior rhinomanometry were performed to identify eventual nasal obstruction and deficits in nasal mucociliary clearance. Olfactory dysfunction was present in 22 (36.6%) patients of the study group: of these, hyposmia was present in 19 (86.4%) and anosmia in 3 (13.6%). The mean TDI score in the study group was 30. A strong correlation between the olfactory dysfunction and severity of sleep apnoea measured using the AHI was found. Patients with OSA would seem to have a high incidence of olfactory dysfunction. The degree of olfactory dysfunction appears to be related to the severity of disease. However, other co-factors such as nasal obstruction and reduced mucociliary clearance might also play a role in of the aetiology of this condition.

Biomarkers of carcinogenesis and tumour growth in patients with cutaneous melanoma and obstructive sleep apnoea

The goal of this study was to assess the relationship between the severity of obstructive sleep apnoea (OSA) and the levels of carcinogenesis- and tumour growth-related biomarkers in patients with cutaneous melanoma.This multicentre observational study included patients who were newly diagnosed with melanoma. The patients were classified as non-OSA (apnoea-hypopnoea index (AHI) 0-5 events·h^-1), mild OSA (AHI 5-15 events·h^-1) and moderate-severe OSA (AHI >15 events·h^-1). ELISAs were performed to analyse the serum levels of hypoxia- and tumour adhesion-related biomarkers (vascular endothelial growth factor (VEGF), interleukin (IL)-8, intracellular adhesion molecule (ICAM) and vascular cell adhesion molecule (VCAM)-1) and markers of tumour aggressiveness (S100 calcium-binding protein B (S100B) and melanoma inhibitory activity (MIA)). A logistic model adjusted for age, sex and body mass index was fitted to each biomarker, and the AHI served as the dependent variable.360 patients were included (52.2% male, median (interquartile range) age 55.5 (43.8-68.0) years and AHI 8.55 (2.8-19.5) events·h^-1). The levels of VEGF, IL-8, ICAM-1, S100B and MIA were not related to the severity of OSA. The levels of VCAM-1 were higher in patients with OSA than those without OSA (mild OSA: odds ratio (OR) 2.07, p=0.021; moderate-severe OSA: OR 2.35, p=0.013).In patients with cutaneous melanoma, OSA was associated with elevated circulating levels of VCAM-1 that could indicate the contribution of OSA in tumorigenesis via integrin-based adhesion.

Role of lung volume and airway inflammation in obstructive sleep apnea

Obstructive sleep apnea (OSA) is a prevalent disorder that affects not only the upper airways but also the intrathoracic airways. In this review, we summarize the results of studies on lung function and airway inflammation. We provide evidence that the alterations in intrathoracic airways observed in OSA are not purely consequences of mechanical trauma and oxidative stress during apneic events but have a causal role in the structural changes associated with OSA and increasing severity of this disorder.

Sleep Disturbance, Sleep Duration, and Inflammation: A Systematic Review and Meta-Analysis of Cohort Studies and Experimental Sleep Deprivation

BACKGROUND

Sleep disturbance is associated with inflammatory disease risk and all-cause mortality. Here, we assess global evidence linking sleep disturbance, sleep duration, and inflammation in adult humans.

METHODS

A systematic search of English language publications was performed, with inclusion of primary research articles that characterized sleep disturbance and/or sleep duration or performed experimental sleep deprivation and assessed inflammation by levels of circulating markers. Effect sizes (ES) and 95% confidence intervals (CI) were extracted and pooled using a random effect model.

RESULTS

A total of 72 studies (n > 50,000) were analyzed with assessment of C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor α (TNFα). Sleep disturbance was associated with higher levels of CRP (ES .12; 95% CI = .05-.19) and IL-6 (ES .20; 95% CI = .08-.31). Shorter sleep duration, but not the extreme of short sleep, was associated with higher levels of CRP (ES .09; 95% CI = .01-.17) but not IL-6 (ES .03; 95% CI: -.09 to .14). The extreme of long sleep duration was associated with higher levels of CRP (ES .17; 95% CI = .01-.34) and IL-6 (ES .11; 95% CI = .02-20). Neither sleep disturbances nor sleep duration was associated with TNFα. Neither experimental sleep deprivation nor sleep restriction was associated with CRP, IL-6, or TNFα. Some heterogeneity among studies was found, but there was no evidence of publication bias.

CONCLUSIONS

Sleep disturbance and long sleep duration, but not short sleep duration, are associated with increases in markers of systemic inflammation.

Cerebral hypoperfusion and glucose hypometabolism: Key pathophysiological modulators promote neurodegeneration, cognitive impairment, and Alzheimer's disease

Aging, hypertension, diabetes, hypoxia/obstructive sleep apnea (OSA), obesity, vitamin B12/folate deficiency, depression, and traumatic brain injury synergistically promote diverse pathological mechanisms including cerebral hypoperfusion and glucose hypometabolism. These risk factors trigger neuroinflammation and oxidative-nitrosative stress that in turn decrease nitric oxide and enhance endothelin, Amyloid-β deposition, cerebral amyloid angiopathy, and blood-brain barrier disruption. Proinflammatory cytokines, endothelin-1, and oxidative-nitrosative stress trigger several pathological feedforward and feedback loops. These upstream factors persist in the brain for decades, upregulating amyloid and tau, before the cognitive decline. These cascades lead to neuronal Ca²⁺ increase, neurodegeneration, cognitive/memory decline, and Alzheimer's disease (AD). However, strategies are available to attenuate cerebral hypoperfusion and glucose hypometabolism and ameliorate cognitive decline. AD is the leading cause of dementia among the elderly. There is significant evidence that pathways involving inflammation and oxidative-nitrosative stress (ONS) play a key pathophysiological role in promoting cognitive dysfunction. Aging and several comorbid conditions mentioned above promote diverse pathologies. These include inflammation, ONS, hypoperfusion, and hypometabolism in the brain. In AD, chronic cerebral hypoperfusion and glucose hypometabolism precede decades before the cognitive decline. These comorbid disease conditions may share and synergistically activate these pathophysiological pathways. Inflammation upregulates cerebrovascular pathology through proinflammatory cytokines, endothelin-1, and nitric oxide (NO). Inflammation-triggered ONS promotes long-term damage involving fatty acids, proteins, DNA, and mitochondria; these amplify and perpetuate several feedforward and feedback pathological loops. The latter includes dysfunctional energy metabolism (compromised mitochondrial ATP production), amyloid-β generation, endothelial dysfunction, and blood-brain-barrier disruption. These lead to decreased cerebral blood flow and chronic cerebral hypoperfusion- that would modulate metabolic dysfunction and neurodegeneration. In essence, hypoperfusion deprives the brain from its two paramount trophic substances, viz., oxygen and nutrients. Consequently, the brain suffers from synaptic dysfunction and neuronal degeneration/loss, leading to both gray and white matter atrophy, cognitive dysfunction, and AD. This Review underscores the importance of treating the above-mentioned comorbid disease conditions to attenuate inflammation and ONS and ameliorate decreased cerebral blood flow and hypometabolism. Additionally, several strategies are described here to control chronic hypoperfusion of the brain and enhance cognition. © 2016 Wiley Periodicals, Inc.

Increasing body condition score is positively associated interleukin-6 and monocyte chemoattractant protein-1 in Labrador retrievers

The accumulation of excess body fat is a growing problem in dogs as well as people. Contrary to prior understanding of adipose tissue, fat is now considered to be an active endocrine organ that promotes a chronic low-grade inflammatory state often characterized by an increase in pro-inflammatory cytokines and chemokines. These have been implicated in several obesity-related disorders such as insulin resistance, cardiovascular disease, and neoplasia. The purpose of this study was to characterize fasting plasma cytokine concentrations in ninety-two healthy client-owned Labrador retriever dogs of various ages and body condition scores. The dogs were grouped according to body condition score (BCS) into three categories, lean, overweight and obese. The following cytokines and chemokines were evaluated; tumor necrosis factor-alpha, interleukin-2, interleukin-6, interleukin-8, and monocyte chemotactic protein-1 (TNF-α, IL-2, IL-6, IL-8, MCP-1). Our results indicated that fasting plasma IL-6 and MCP-1 concentrations are associated with increasing BCS. This data suggest that certain markers of inflammation increase with increasing body condition score, and that dogs, similar to humans, may be fostering a chronic inflammatory state due to obesity.

Exhaled Breath Condensate: Technical and Diagnostic Aspects

Purpose. The aim of this study was to evaluate the 30-year progress of research on exhaled breath condensate in a disease-based approach. Methods. We searched PubMed/Medline, ScienceDirect, and Google Scholar using the following keywords: exhaled breath condensate (EBC), biomarkers, pH, asthma, gastroesophageal reflux (GERD), smoking, COPD, lung cancer, NSCLC, mechanical ventilation, cystic fibrosis, pulmonary arterial hypertension (PAH), idiopathic pulmonary fibrosis, interstitial lung diseases, obstructive sleep apnea (OSA), and drugs. Results. We found 12600 related articles in total in Google Scholar, 1807 in ScienceDirect, and 1081 in PubMed/Medline, published from 1980 to October 2014. 228 original investigation and review articles were eligible. Conclusions. There is rapidly increasing number of innovative articles, covering all the areas of modern respiratory medicine and expanding EBC potential clinical applications to other fields of internal medicine. However, the majority of published papers represent the results of small-scale studies and thus current knowledge must be further evaluated in large cohorts. In regard to the potential clinical use of EBC-analysis, several limitations must be pointed out, including poor reproducibility of biomarkers and absence of large surveys towards determination of reference-normal values. In conclusion, contemporary EBC-analysis is an intriguing achievement, but still in early stage when it comes to its application in clinical practice.