Eight months of continuous positive airway pressure (CPAP) decrease tumor necrosis factor alpha (TNFA) in men with obstructive sleep apnea syndrome

Patients with obstructive sleep apnea have suppressed levels of soluble cytokine receptors involved in neurodegenerative disease, but normal levels with airways therapy

Purpose

Obstructive sleep apnea (OSA) results in systemic intermittent hypoxia. By one model, hypoxic stress signaling in OSA patients alters the levels of inflammatory soluble cytokines TNF and IL6, damages the blood brain barrier, and activates microglial targeting of neuronal cell death to increase the risk of neurodegenerative disorders and other diseases. However, it is not yet clear if OSA significantly alters the levels of the soluble isoforms of TNF receptors TNFR1 and TNFR2 and IL6 receptor (IL6R) and co-receptor gp130, which have the potential to modulate TNF and IL6 signaling.

Methods

Picogram per milliliter levels of the soluble isoforms of these four cytokine receptors were estimated in OSA patients, in OSA patients receiving airways therapy, and in healthy control subjects. Triplicate samples were examined using Bio-Plex fluorescent bead microfluidic technology. The statistical significance of cytokine data was estimated using the nonparametric Wilcoxon rank-sum test. The clustering of these high-dimensional data was visualized using t-distributed stochastic neighbor embedding (t-SNE).

Results

OSA patients had significant twofold to sevenfold reductions in the soluble serum isoforms of all four cytokine receptors, gp130, IL6R, TNFR1, and TNFR2, as compared with control individuals (p = 1.8 × 10⁻¹³ to 4 × 10⁻⁸). Relative to untreated OSA patients, airways therapy of OSA patients had significantly higher levels of gp130 (p = 2.8 × 10⁻¹³), IL6R (p = 1.1 × 10⁻⁹), TNFR1 (p = 2.5 × 10⁻¹⁰), and TNFR2 (p = 5.7 × 10⁻⁹), levels indistinguishable from controls (p = 0.29 to 0.95). The data for most airway-treated patients clustered with healthy controls, but the data for a few airway-treated patients clustered with apneic patients.

Conclusions

Patients with OSA have aberrantly low levels of four soluble cytokine receptors associated with neurodegenerative disease, gp130, IL6R, TNFR1, and TNFR2. Most OSA patients receiving airways therapy have receptor levels indistinguishable from healthy controls, suggesting a chronic intermittent hypoxia may be one of the factors contributing to low receptor levels in untreated OSA patients.

Electronic supplementary material

The online version of this article (10.1007/s11325-020-02205-y) contains supplementary material, which is available to authorized users.

Airways therapy of obstructive sleep apnea dramatically improves aberrant levels of soluble cytokines involved in autoimmune disease

Obstructive Sleep Apnea (OSA) damages the health of 35% of adult Americans. Disordered sleep results in increased risk of several autoimmune disorders, but the molecular links to autoimmunity are poorly understood. Herein, we identified four cytokines associated with autoimmune disease, whose median serum levels were significantly different for OSA patients receiving airways therapy, from the levels in untreated OSA patients, APRIL (5.2-fold lower, p = 3.5 × 10^-11), CD30 (1.6-fold higher, p = 7.7 × 10^-5), IFN-Alpha-2 (2.9-fold higher, p = 9.6 × 10^-14) and IL-2 (1.9-fold higher, p = 0.0003). Cytokine levels in airways treated patients were similar to the levels in control subjects. t-SNE and UMAP analysis of these high dimensional patient cytokine data identified only two groups, suggesting a similar global response for all four cytokines to airways therapy. Our findings suggest the levels of these four cytokines may be altered by disordered sleep and perhaps by chronic hypoxia. Therapeutic options are discussed.

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

Obstructive sleep apnea syndrome (OSAS) is a markedly prevalent condition across the lifespan, particularly in overweight and obese individuals, which has been associated with an independent risk for neurocognitive, behavioral, and mood problems as well as cardiovascular and metabolic morbidities, ultimately fostering increases in overall mortality rates. In adult patients, excessive daytime sleepiness (EDS) is the most frequent symptom leading to clinical referral for evaluation and treatment, but classic EDS features are less likely to be reported in children, particularly among those with normal body-mass index. The cumulative evidence collected over the last two decades supports a conceptual framework, whereby sleep-disordered breathing in general and more particularly OSAS should be viewed as low-grade chronic inflammatory diseases. Accordingly, it is assumed that a proportion of the morbid phenotypic signature in OSAS is causally explained by underlying inflammatory processes inducing end-organ dysfunction. Here, the published links between OSAS and systemic inflammation will be critically reviewed, with special focus on the pro-inflammatory cytokines tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6), since these constitute classical prototypes of the large spectrum of inflammatory molecules that have been explored in OSAS patients.

The relationship between sleep apnea, metabolic dysfunction and inflammation: The gender influence

Obstructive sleep apnea (OSA) has been associated with increased risk of cardiovascular morbidity and mortality. Although inflammatory markers may mediate this association, it is unknown the influence of gender in this mechanism. Thus, we aimed to evaluate the interaction effects between OSA and gender on metabolic and inflammatory profile in a population sample. This study is part of EPISONO cohort, in which 1042 participants underwent polysomnography, answered questionnaires, and had their blood collected for analysis of fasting glucose, total cholesterol and fractions, leptin, ghrelin, liver transaminases, tumor necrosis factor (TNF)-α, interleukin (IL)-6, and C-reactive protein. The results showed that men with OSA had higher leptin levels, shorter sleep latency and lower N3 sleep stage compared to men control (CTRL). They also presented higher apnea index and number of central apneas compared to both CTRL men and OSA women. In women, OSA was related to longer REM sleep latency, higher apnea-hypopnea index (AHI) during REM sleep and increased TNF-α levels compared to CTRL women. A multivariate model showed that male gender, ghrelin and total cholesterol were negatively associated with TNF-α, while IL-6, triglycerides and hypopnea index were positively associated (R²=0.21). Additionally, gender (men), body mass index, ghrelin, apnea index and smoking were positive predictors of leptin levels (R²=0.55). Of note, postmenopause was associated with changes observed in both TNF-α and AHI during REM sleep in women with OSA. Taken together, our study suggests that OSA consequences may differ between genders and this could indicate a need for different OSA management in women according to their reproductive life's stage.

Biomarkers to improve diagnosis and monitoring of obstructive sleep apnea syndrome: current status and future perspectives

Obstructive sleep apnea syndrome (OSAS) is characterized by recurrent episodes of upper airway collapse associated with oxygen desaturation and sleep disruption. It is proposed that these periodic changes lead to molecular variations that can be detected by assessing serum biomarkers. Studies have identified inflammatory, oxidative, and metabolic perturbations attributable to sleep-disordered breathing. Given that OSAS is associated with increased cardiovascular and cerebrovascular morbidity, the ideal biomarker should enable timely recognition with the possibility of intervention. There is accumulating data on the utility of serum biomarkers for the evaluation of disease severity, prognosis, and response to treatment. However, current knowledge is limited by data collection techniques, disease complexity, and potential confounding factors. The current paper reviews the literature on the use of serum biomarkers in OSAS. It is concluded that the ideal serum biomarker still needs to be discovered, while caution is needed in the interpretation of hitherto available results.

Intracranial hypertension associated with obstructive sleep apnea: a discussion of potential etiologic factors

Obstructive sleep apnea has been shown to increase intracranial pressure, and to be a secondary cause of intracranial hypertension. There are a few theories that attempt to explain this relationship, however there is little data, and even less recognition among physicians that this actually occurs. This paper discusses multiple pieces of data, from anatomical correlates to biochemical information involving neuro-excitotoxicity, as well as hematologic factors and issues surrounding brain edema and blood-brain barrier dysfunction. A complex paradigm for how obstructive sleep apnea may lead to increased intracranial pressure is thus proposed. In addition, suggestions are made for how obstructive sleep apnea must as a result be managed differently in the setting of idiopathic intracranial hypertension.

Addressing sleep disturbances: an opportunity to prevent cardiometabolic disease?

There is increasing awareness of the role of sleep disturbance as an important factor in health and disease. Although sub-clinical sleep disturbances (insufficient sleep duration or inadequate sleep quality) may be difficult to assess with conceptual and/or methodological clarity, this review attempts to summarize and synthesize these findings. First, the concept of sleep disturbance in a public health context is introduced, to provide context and rationale. Second, operational definitions of 'cardiometabolic disease' and 'sleep disturbance' are offered, to address many unclear operationalizations. Third, the extant literature is summarized regarding short or long sleep duration and/or insufficient sleep, insomnia and insomnia symptoms, general (non-specific sleep disturbances), circadian rhythm abnormalities that result in sleep disturbances, and, briefly, sleep-disordered breathing. Fourth, the review highlights the social/behavioural context of sleep, including discussions of sleep and race/ethnicity, socio-economic position, and other social/environmental factors, in order to place these findings in a social-environmental context relevant to public health. Fifth, the review highlights the issue of sleep as a domain of health behaviour and addresses issues regarding development of healthy sleep interventions. Finally, a research agenda of future directions is proposed.

Can gestational hypertension be modified by treating nocturnal airflow limitation?

OBJECTIVE

Recent evidence suggests that women with gestational hypertension (GH) have a high rate of sleep disordered breathing (SDB), and treatment for even marginal SDB may improve blood pressure control in women with GH. We assessed whether the application SDB treatment could improve blood pressure in women with GH.

METHODS

This was a single-center randomized study. Subjects underwent an unattended home-based diagnostic sleep study. The study was then repeated with subjects wearing one of two randomly assigned treatments: auto-titrating continuous positive airway pressure (auto-CPAP) or mandibular advancement device (MAD) + nasal strip. First morning blood pressure and blood for standard GH measures plus inflammatory markers were taken after each study. Subjects completed a series of questionnaires addressing sleep quality and tolerance of assigned therapy.

RESULTS

Twenty-four women completed the protocol-13 in the MAD group and 11 in auto-CPAP. The overall rate of SDB was 38%. Auto-CPAP was more effective at treating SDB than MAD + nasal strip, although the women randomized to MAD + nasal strip reported the greater comfort with therapy. First morning blood pressure was not consistently improved with either therapy. When subjects were stratified according to those whose blood pressure increased or decreased with therapy, an association was suggested between blood pressure improvement and reduced levels of tumour necrosis factor-α.

CONCLUSION

We demonstrated that 38% of women with GH had concurrent SDB. We did not find an improvement in blood pressure or inflammatory markers with a single night of either the auto-CPAP or MAD + nasal strip interventions. However important lessons from this study may guide future investigations in this area.

Profile of circulating cytokines: impact of OSA, obesity and acute cardiovascular events

Obstructive sleep apnea (OSA) is inducing oxidative stress and consequently promotes systemic inflammation and cardiovascular morbidity. The respective impact of obesity, sleep apnea and acute cardiovascular events on the profile of inflammatory cytokines has not been extensively evaluated. We examined the profile of circulating cytokines in a case-control study comparing nonobese or obese patients with or without sleep apnea and with or without an acute cardiovascular event. Patients were assessed by sleep studies and inflammatory (hs-CRP, Leptin, RANTES, MCP1, IL6, IL8, TNF-α) and anti-inflammatory (adiponectin, IL1-Ra) cytokines profile. A cardiovascular phenotyping was performed including carotid intima-media thickness, pulse wave velocity and 24h blood pressure monitoring. In comparison with patients without sleep apnea or without comorbidities, patients with the combination of an acute cardiovascular event and pre-existing sleep apnea showed a higher burden of systemic inflammation with significant increase in serum levels of hs-CRP, IL1-Ra, IL-8, IL-6, TNF-α, Rantes and sICAM. Rantes and sICAM serum levels were independently associated with AHI after an acute cardiovascular event. Serum levels of different inflammatory markers were significantly increased in patients with the combination of sleep apnea and an acute cardiovascular event. Since these biomarkers could be associated with worsened cardiovascular outcome, diagnosing and treating associated sleep apnea is potentially important in patients after an acute cardiovascular event.

Fatigue, tiredness, lack of energy, and sleepiness in multiple sclerosis patients referred for clinical polysomnography

Objectives. To assess the relationship between nocturnal polysomnographic (PSG) findings and a group of key self-reported symptoms-fatigue, tiredness, lack of energy, and sleepiness-among sleep-laboratory referred patients with and without multiple sclerosis (MS). Methods. PSG and questionnaire data from n = 30 MS patients and n = 30 matched controls were analyzed retrospectively. Associations between symptoms of fatigue, tiredness, lack of energy, sleepiness, and PSG variables of interest were examined among MS patients and controls. Results. More MS patients than controls reported fatigue, tiredness, and lack of energy to occur often or almost always (Chi-square P < 0.0001 for each), but sleepiness was reported similarly by both groups (P = 0.3409). Among MS patients, tiredness correlated with sleepiness (Spearman correlation P = 0.005), and a trend emerged toward correlation between fatigue and sleepiness (Spearman correlation P = 0.076). Decreased sleep efficiency on PSGs correlated with fatigue, tiredness, and lack of energy in MS patients (Spearman correlation P = 0.002, 0.029, and 0.048, resp.), but not sleepiness or any symptom among controls. Conclusion. In comparison to controls, MS patients report more fatigue, tiredness, and lack energy, but not sleepiness. Fatigue and related symptoms may arise from MS itself or in relation to reduced sleep efficiency.

Influence of CPAP treatment on airway and systemic inflammation in OSAS patients

AIM

Obstructive sleep apnea syndrome (OSAS) is characterized by recurrent respiratory disorders in the upper airways during sleep. Although continuous positive airway pressure (CPAP) has been accepted to be the most effective treatment for OSAS, its role on inflammation remains debatable. In this study, our aim was to examine the influence of 3 months of CPAP treatment on tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), 8-isoprostane, and peroxynitrite levels in exhaled breathing condensates (EBC) and serum.

METHODS

Thirty-five patients who were newly diagnosed as moderate or severe OSAS with full night polysomnography and used CPAP therapy regularly for 3 months were included in the study. Polysomnography, spirometric tests, fasting blood samples, and EBC were ascertained on entry into the study and after 3 months of treatment. All patients were assessed monthly for treatment adherence and side effects.

RESULTS

We found that all polysomnographic parameters were normalized after CPAP therapy in the control polysomnogram. Also, all markers in EBC and nitrotyrosine and 8-isoprostane levels in serum were decreased significantly with CPAP treatment. Sedimentation rate, C-reactive protein, IL-6, and TNF-α remained unchanged in serum after treatment. We found that baseline nitrotyrosine levels were significantly correlated with apnea-hypopnea index, oxygen desaturation index, and percent time in SpO2 < 90 % (p < 0.01).

CONCLUSIONS

CPAP therapy has primarily a relevant impact on airways, and nitrotyrosine levels correlated well with severity of OSAS. This treatment decreases both inflammation and oxidative stress levels in airways in OSAS patients. Also, this treatment helps to decrease systemic oxidative stress levels in serum.