Serum inflammatory markers in obstructive sleep apnea: a meta-analysis

Association between tumor necrosis factor alpha and obstructive sleep apnea in adults: a meta-analysis update

BACKGROUND

Tumor necrosis factor-α (TNF-α) has been reported to play a part in the development of obstructive sleep apnea (OSA) and its complications. However, the relationship between TNF-α and OSA still remains inconclusive. We aimed to systematically review and synthesize studies published to date on association between the two in adults.

METHODS

We searched for English-language articles containing original human data from case-control study studies in adults≥18 years of age. The selection criteria were set according to the PICOS framework. Articles were independently reviewed by three investigators. Data regarding demographics, clinical characteristics, and TNF-α levels were obtained. A random-effects model was applied to evaluate the overall effect sizes by calculating standard mean difference (SMD) and its 95% confidence intervals (CIs).

RESULTS

Of 393 identified abstracts, 50 articles (3503 OSA patients and 3379 health controls) were ultimately included in this meta-analysis. The results indicated that the TNF-α level in patients with OSA was 1.77 (95%CI, 1.37 to 2.17, I² = 97.8%, P < 0.0001) times higher than in the control group. Subgroup analyses showed a positive correlation between the level of TNF-α and OSA severity. According to meta-regression, we noted that aging significantly predicted an increased effect size of TNF-α level in OSA patients (P < 0.007).

CONCLUSION

This study identified a significant association between OSA and elevated TNF-α level in adults. Meanwhile, TNF-α levels were consistently correlated with severity of OSA, which indicated it might be a promising biomarker for the development of OSA. However, well-designed, large-scale, case-control cohorts are needed to better understand the relationship of TNF-α in the context of adult OSA.

The relationship between inflammation and neurocognitive dysfunction in obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS), a state of sleep disorder, is characterized by repetitive apnea, chronic hypoxia, oxygen desaturation, and hypercapnia. Previous studies have revealed that intermittent hypoxia (IH) conditions in OSAS patients elicited neuron injury (especially in the hippocampus and cortex), leading to cognitive dysfunction, a significant and extraordinary complication of OSAS patients. The repeated courses of airway collapse and obstruction in OSAS patients resulted in apnea and arousal during sleep, leading to IH and excessive daytime sleepiness (EDS) and subsequently contributing to the development of inflammation. IH-mediated inflammation could further trigger various types of cognitive dysfunction. Many researchers have found that, besides continuous positive airway pressure (CPAP) treatment and surgery, anti-inflammatory substances might alleviate IH-induced neurocognitive dysfunction. Clarifying the role of inflammation in IH-mediated cognitive impairment is crucial for potentially valuable therapies and future research in the related domain. The objective of this article was to critically review the relationship between inflammation and cognitive deficits in OSAS.

Evaluation of Serum and Plasma Interleukin-6 Levels in Obstructive Sleep Apnea Syndrome: A Meta-Analysis and Meta-Regression

Obstructive sleep apnea syndrome (OSAS) is considered a low-grade chronic inflammatory disease. Interleukin-6 (IL-6) is one of the most significant inflammatory markers and an excellent proxy for the inflammatory/immune system. The present meta-analysis and meta-regression aimed at comparing plasma and serum levels of IL-6 between individuals (children and adults) with OSAS and healthy controls. Four databases, PubMed/Medline, Scopus, Cochrane Library, and Web of Science, were comprehensively searched to retrieve articles published up to December, 2019, with no further restrictions. RevMan 5.3 software was used to calculate the crude mean difference (MD) and 95% confidence interval (CI). The results of funnel plots and meta-regression were analyzed by the CMA 2.0 software. Sixty-three studies (57 with adults; six with children) were included in the present meta-analysis. For adults, 37 studies reported significantly higher serum IL-6 levels and 20 reported significantly higher plasma IL-6 levels for those with OSAS than for healthy controls [pooled MD of 2.89 pg/ml (P < 0.00001) and pooled MD of 2.89 pg/ml (P < 0.00001), respectively]. The pooled analysis of serum and plasma IL-6 levels in children with OSAS compared with controls revealed that only the MD of plasma IL-6 levels was significant (MD = 0.84 pg/ml, P = 0.004). Results of the meta-regression showed that greater age was associated with higher serum IL-6 levels. Egger's test revealed a publication bias across the studies for serum and plasma IL-6 levels (P = 0.00044 and P = 0.01445, respectively). In summary, the meta-analysis and meta-regression confirmed that, compared to healthy controls, individuals with OSAS (children and adults) had higher serum/plasma IL-6 levels.

Association between the neutrophil-to-lymphocyte ratio and obstructive sleep apnea: a meta-analysis

This meta-analysis is aimed to investigate the association between the neutrophil-to-lymphocyte ratio (NLR) and obstructive sleep apnea (OSA). The PubMed, Web of Science, Google Scholar, and Cochrane Library databases were searched to collect all relevant articles. The pooled standardized mean difference (SMD) with a 95% confidence interval (CI) was calculated using the random effects model. In addition, subgroup analysis and meta-regression analysis were performed. Eleven eligible articles containing 2,259 patients with OSA were included in this study. Pooled outcomes revealed that the NLR was significantly higher in patients with OSA than in controls (SMD 0.62, 95% CI 0.29–0.94, P = 0.002). In subgroup analyses, differences in the NLR between patients and controls increased with worsening OSA grades. Furthermore, meta-regression analysis showed that differences in mean BMI exerted a significant effect on differences in the NLR (P = 0.0003). In summary, our meta-analysis demonstrated that the NLR in OSA patients was significantly higher than that in controls, and the difference was larger in patients with severe OSA. These results indicate that the NLR may be a reliable marker for detecting systemic inflammation and predicting disease severity in patients with OSA.

Serum and Plasma Tumor Necrosis Factor Alpha Levels in Individuals with Obstructive Sleep Apnea Syndrome: A Meta-Analysis and Meta-Regression

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is associated with a variety of inflammatory factors. Specifically, proinflammatory cytokines appear to be associated with the pathogenesis of OSAS.

METHODS

For the present meta-analysis and meta-regression on serum and plasma tumor necrosis factor alpha (TNF-α) levels in individuals with and without OSAS, we performed a systematic search without any restrictions of the PubMed/Medline, Scopus, Cochrane Library, and Web of Science databases to find relevant articles published up to February 1, 2020.

RESULTS

Fifty-five (adults: 29 studies on serum and 17 studies on plasma; children: 4 studies on serum and 5 studies on plasma) were included and analyzed. Always compared to age-matched healthy controls, the pooled MDs were as follows: adults, serum: 10.22 pg/mL (95% CI = 8.86, 11.58; p < 0.00001); adults, plasma: 5.90 pg/mL (95% CI = 4.00, 7.80; p < 0.00001); children, serum: 0.21 pg/mL (95% CI = 0.05, 0.37; p = 0.01); children, plasma: 5.90 pg/mL (95% CI = 4.00, 7.80; p < 0.00001).

CONCLUSIONS

Compared to healthy and age-matched controls, adult individuals with OSAS had significantly higher serum/plasma TNF-α levels. For children with OSAS, significantly higher levels were observed for TNF-α in serum but not in plasma.

Structural assessment of the optic nerve in patients with obstructive sleep apnea syndrome: Case-control study

OBJECTIVE

Obstructive sleep apnea syndrome has been identified as a possible risk factor for optic nerve pathology such as glaucoma, nonarteritic ischemic optic neuropathy, and optic disk edema. Accordingly, we aimed to evaluate structural changes of the apparently normal optic nerve in obstructive sleep apnea syndrome patients with effects of its severity.

MATERIALS AND METHODS

In this prospective case-control study, 47 eyes of 47 obstructive sleep apnea syndrome patients diagnosed with polysomnography and 40 eyes of 40 healthy subjects were included. Spectral-domain optical coherence tomography was used to evaluate the peripapillary retinal nerve fiber layer thickness, optic nerve head topographic parameters, and retinal ganglion cell-inner plexiform layer thickness.

RESULTS

The average peripapillary nerve fiber layer thickness was lower in obstructive sleep apnea syndrome patients than in controls (90.74 ± 7.98 vs 94.93 ± 6.13 μm; p = 0.008). The average cup/disk ratio and the vertical cup/disk ratio in patients with OSAS were significantly higher compared to the controls (both p < 0.001). However, no significant difference in retinal ganglion cell-inner plexiform layer thickness was found.

CONCLUSION

Even if the retinal ganglion cell-inner plexiform layer thicknesses did not significantly differ between the obstructive sleep apnea syndrome and control groups, obstructive sleep apnea syndrome patients showed a decreased peripapillary nerve fiber layer thickness and increased optic nerve head parameters. These findings can be used as an indicator of optic nerve damage in the early diagnosis of obstructive sleep apnea syndrome patients.

Is there a relationship between hematological parameters and duration of respiratory events in severe OSA

Aim: The aim of this study was to compare hematological parameters with the mean obstructive apnea duration (MOAD), mean mixed apnea duration (MMAD), mean central apnea duration (MCAD), mean total apnea duration (MTAD) and mean hypopnea duration (MHD), and blood oxygenation, other polysomnographic sleep parameters in patients with severe OSA.Material and methods: A retrospective study included 120 patients with severe OSA. The correlations between the hematological parameters with MOAD, MMAD, MCAD, MTAD, MHD, and blood oxygenation, other polysomnographic sleep parameters were analyzed.Results: There was a positive correlation between hgb with MOAD, MMAD, MTAD MCAD, MHD; mean oxygen desaturation, and the number of desaturation (≥5%). Also, hgb associated negatively with N1 sleep, WASO (wake time after sleep onset) and positively with REM, N2 sleep, total sleep time, and sleep efficiency. RDW and MOAD, MTAD, MHD were negatively related. Also, RDW related positively with sleep latency, WASO, and N1 sleep; negatively with sleep efficiency and REM sleep. There was no relationship between duration of respiratory events with NLR, PRL, and MPV.Conclusions: Hematological parameters, especially hgb and RDW, can be used to assess the severity of the disease in severe OSA patients in addition to AHI.

C reactive protein elevation among children or among mothers' of children with autism during pregnancy, a review and meta-analysis

OBJECTIVE

To evaluate if children with ASD, or mothers of ASD children have elevated CRP during pregnancy.

BACKGROUND

Autism spectrum disorder (ASD) is a neuro developmental disorder with incidence of 1 in 68 children occur in all racial, ethnic, and socioeconomic groups. Economic burden between $11.5 billion - $60.9 billion and family average medical expenditures of $4110-$6200 per year. Conflicting evidence exist about role of maternal CRP during pregnancy with ASD child.

METHODS

Searches on database; Pubmed, Medline, Embase and google scholar using key words; C reactive protein (CRP), Maternal CRP, ASD, autism, autistic disorder, Inflammation. All English-language studies published between 1960 and 2019 pertaining to CRP and ASD. All Studies which provided data on CRP levels during pregnancy (mCRP) of Mothers of offsprings with ASD and (mCRP) of mothers of normal subjects were selected. Data were extracted in the form of odd ratios of having high mCRP in mothers of children with ASD versus mCRP of mothers of normal controls. Since these odd ratios were adjusted, therefore no Meta regression were attempted. Significant heterogeneity was found; therefore, random effect model was employed.

RESULTS

Review of CRP levels in children with ASD showed higher level in children with ASD than control, although different methodology and absence of numerical data did not allow metanalysis. Regarding mCRP and ASD, three studies were identified that provide data on mCRP and ASD. Four datasets were created from these 3 studies as the study by Zerbo et al. provided data in 2 subsets. Total number of subjects were 5258 (Brown, N = 677, Zerbo = 416, Koks = 4165) extracted data from these studies was pooled for analysis. Random effect model was employed and substantial heterogeneity among the studies was observed 11. Mothers of children with ASD have adjusted Odd ratio of 1.02 (0.948 to 1.103, I2 = 75, P = 0.558) to have high mCRP comparing mothers of control.

CONCLUSION

Mothers of children with ASD appear not to have elevated CRP during pregnancy. Children with ASD appear to have higher levels of CRP levels.

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.

Risk factors of excessive daytime sleepiness in a prospective population-based cohort

Although excessive daytime sleepiness is commonly evaluated in clinical and research settings using the Epworth Sleepiness Scale, few studies have assessed the factors associated with its incidence in the general population. We prospectively investigated the predictors of incident and persistent excessive daytime sleepiness in 2,751 subjects (46.1% men, mean age 56.0 ± 9.8 years) from the CoLaus-PsyCoLaus population-based cohort (Lausanne, Switzerland) over 5 years. Participants completed the Epworth Sleepiness Scale and the Pittsburgh Sleep Quality Index, and underwent a full clinical evaluation at baseline and 5 years afterwards. Ambulatory polysomnography was performed at baseline in a sub-sample of 1,404 subjects. Among the 2,438 subjects without excessive daytime sleepiness (Epworth Sleepiness Scale ≤ 10) at baseline, the 5-year incidence of excessive daytime sleepiness was 5.1% (n = 124). Multivariate logistic regression revealed that male sex, depressive symptoms, reported poor sleep quality and moderate to severe obstructive sleep apnea were independent predictors of incident excessive daytime sleepiness, while older age, moderate coffee consumption, periodic leg movement during sleep and hypertension were independent protective factors. Stratified analysis according to sex and age showed some distinctive associations. Among the 313 patients with excessive daytime sleepiness at baseline, 137 (43.8%) had persistent excessive daytime sleepiness 5 years later. Our findings provide new insights into the predictors of incident excessive daytime sleepiness, but interventional studies are needed to understand the impact of treating these risk factors on the incidence of excessive daytime sleepiness.

Effect of continuous positive airway pressure on inflammatory, antioxidant, and depression biomarkers in women with obstructive sleep apnea: a randomized controlled trial

STUDY OBJECTIVES

The effect of continuous positive airway pressure (CPAP) on mediators of cardiovascular disease and depression in women with obstructive sleep apnea (OSA) is unknown. We aimed to assess the effect of CPAP therapy on a variety of biomarkers of inflammation, antioxidant activity, and depression in women with OSA.

METHODS

We conducted a multicenter, randomized controlled trial in 247 women diagnosed with moderate-to-severe OSA (apnea-hypopnea index [AHI] ≥ 15). Women were randomized to CPAP (n = 120) or conservative treatment (n = 127) for 12 weeks. Changes in tumor necrosis factor α (TNFα), interleukin 6 (IL-6), C-reactive protein (CRP), intercellular adhesion molecule 1 (ICAM-1), catalase (CAT), superoxide dismutase (SOD), and brain-derived neurotrophic factor (BDNF) were assessed. Additional analyses were conducted in subgroups of clinical interest.

RESULTS

Women had a median (25th-75th percentiles) age of 58 (51-65) years, body mass index 33.5 (29.0-38.3) kg/m2, and AHI 33.3 (22.8-49.3). No differences were found between groups in the baseline levels of the biomarkers. After 12 weeks of follow-up, there were no changes between groups in any of the biomarkers assessed. These results did not change when the analyses were restricted to sleepy women or to those with severe OSA. In women with CPAP use at least 5 hours per night, only TNFα levels decreased compared to the control group (-0.29 ± 1.1 vs -0.06 ± 0.53, intergroup difference -0.23 [95% CI = -0.03 to -0.50]; p = 0.043).

CONCLUSIONS

Twelve weeks of CPAP therapy does not improve biomarkers of inflammation, antioxidant activity, or depression compared to conservative treatment in women with moderate-to-severe OSA.

TRIAL REGISTRATION

NCT02047071.

Pathology of unexpected sudden cardiac death: Obstructive sleep apnea is part of the challenge

Unexpected sudden cardiac death (SCD), sudden infant death syndrome (SIDS) and sudden intrauterine unexplained death (SIUD) are major unsolved, devastating forms of death that occur frequently. Obstructive sleep apnea (OSA) has been associated with increased cardiovascular and cerebrovascular morbidity and mortality, including sudden cardiac death (SCD). This editorial will review the pathology of SCD, including sudden infant death syndrome (SIDS) and sudden intrauterine unexplained death (SIUD); OSA with its cardiovascular consequences; the possible link between SCD and OSA, discussing the potential mechanisms underlying these two frequent, but yet overlooked pathologies. Finally, the possible preventive benefits of treating OSA and identifying patients at common risk for OSA and SCD and SIDS-SIUD to prevent unexpected deaths will be discussed. Post-mortem examination is of great importance in every case of SCD sine materia, with examination of the brainstem and cardiac conduction system on serial sections, when general autopsy fails, but it should be stressed that also the investigations of patients suffering from OSA should focus on the possibility of pathological findings in common with cases of SCD.

Diastolic dysfunction in men with severe obstructive sleep apnea syndrome but without cardiovascular or oxidative stress-related comorbidities

Background:

We aimed to evaluate whether the severity of obstructive sleep apnea syndrome (OSAS) per se affects the prevalence of left ventricular (LV) diastolic dysfunction in patients without comorbidities.

Methods:

A total of 42 patients with first-diagnosed severe OSAS [apnea–hypopnea index (AHI) > 30] and 25 controls (AHI < 5), having been referred for snoring to the Sleep Laboratory Department of our tertiary Hospital, were enrolled in the study. Inclusion criteria were absence of any cardiovascular or oxidative stress-related comorbidities, and age between 20 and 70 years. Clinical, laboratory, echocardiographic, and polysomnographic data were recorded prospectively. Diastolic dysfunction diagnosis and grading was based on 2016 ASE/EACVI recommendations.

Results:

Severe OSAS was associated with significantly increased prevalence and degree of diastolic dysfunction (26/42; 61.9%) compared with controls (7/25; 28%) (p = 0.007). AHI ⩾ 55 (dichotomous value of severe OSAS subset) was also characterized by greater prevalence and degree of diastolic dysfunction compared with 30 < AHI < 55 patients (p = 0.015). In the severe OSAS subset, age >45 years-old, height <1.745 m, body-mass index (BMI) >27.76 kg m⁻², OSAS severity (AHI > 57.35), oxidative stress (overnight reduction of reduced to oxidized glutathione ratio < 18.44%), and BMI/height ratio > 16.155 kg m⁻³ (an index describing ‘dense’, short-heavy patients) presented significant diagnostic utility in identifying diastolic dysfunction in ROC-curve analysis (0.697 ⩾ AUC ⩾ 0.855, 0.001 ⩽ p ⩽ 0.018). In binary logistic regression model, advanced age (OR 1.23, 95% CI 1.025–1.477; p = 0.026) and AHI (OR 1.123, 95% CI 1.007–1.253; p = 0.036) showed independent association with diastolic dysfunction in severe OSAS.

Conclusions:

The present prospective study may suggest that severe OSAS is significantly associated with LV diastolic dysfunction; OSAS clinical severity exerts a positive influence on (and possibly constitutes an independent risk factor of) LV diastolic dysfunction.

The reviews of this paper are available via the supplementary material section.

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.

Associations of Inflammation, Physical Activity, and Sleep in a Diverse Population of Women

Background: Cardiovascular disease (CVD) is the leading cause of mortality in United States with a recent rise seen in young adults, particularly women. Systemic inflammation, physical activity, and sleep are each individually linked to CVD risk. Whether there is an interaction of these variables, however, is unclear. We evaluated physical activity and sleep among racially ethnically diverse women, ages 20-79 years, to assess associations with systemic inflammation. Methods: We performed a cross-sectional study of 506 women (61% racial/ethnic minority; mean (standard deviation [SD]) age = 37 [15.7] years, body mass index 26.0 [5.7] kg/m²) enrolled in the American Heart Association (AHA) Go Red for Women Strategically Focused Research Network at Columbia University Irving Medical Center (CUIMC). Inflammation, assessed by C-reactive protein (CRP), was analyzed in the Biomarkers Core Laboratory at CUIMC. Physical activity and sleep were assessed using validated questionnaires. Multivariable models adjusted for demographic and clinical confounders were used to evaluate associations between CRP, physical activity, and sleep. Results: Mean (SD) physical activity was 282 (557.2) minutes/week, and mean (SD) sleep duration was 6.75 (1.24) hours/night. Mean CRP was 2.08 (3.56), and 17% of participants were categorized as high risk for obstructive sleep apnea (OSA). Participants who slept <6 hours/night were less likely to be physically active ≥150 minutes/week (odds ratios, ORs [95% confidence interval, CI]: 0.53 [0.33-0.84]). This association was nonsignificant after adjustment. High risk of OSA was associated with CRP ≥2 mg/L (OR [95% CI]: 1.91 [1.11-3.30]) following adjustment. Stratification by race/ethnicity showed that high risk of OSA was associated with CRP ≥2 mg/L among racial/ethnic minorities but not white women (OR [95% CI]: 2.75 [1.43-5.30] vs. 0.94 [0.31-2.88]). Conclusion: High risk of OSA and elevated CRP was significantly associated in women, particularly minority women. Both play a role in CVD, highlighting potential causes for the increased risk of CVD in younger women.

Relationships Among and Predictive Values of Obesity, Inflammation Markers, and Disease Severity in Pediatric Patients with Obstructive Sleep Apnea Before and After Adenotonsillectomy

Both obstructive sleep apnea (OSA) and obesity are major health issues that contribute to increased systemic inflammation in children. To date, adenotonsillectomy (AT) is still the first-line treatment for childhood OSA. However, the relationships among and predictive values of obesity, inflammation, and OSA severity have not been comprehensively investigated. This prospective study investigated body mass index (BMI), serum inflammatory markers, and OSA severity before and after AT in 60 pediatric patients with OSA. At baseline, differences in levels of interleukin-6, interleukin-9, basic fibroblast growth factor, platelet-derived growth factor-BB, as well as regulated on activation, normal T cell expressed and secreted (RANTES) were significant among the various weight status and OSA severity subgroups. After 3 months postoperatively, the differences in these inflammatory markers diminished along with a decrease in OSA severity while obesity persisted. The rate of surgical cure (defined as postoperative obstructive apnea-hypopnea index < 2.0 and obstructive apnea index < 1.0) was 62%. Multivariate analysis revealed that age, BMI z-score, granulocyte-macrophage colony-stimulating factor, monocyte chemotactic protein-1, and RANTES independently predicted surgical cure. Despite the significant reductions in inflammatory markers and OSA severity after AT, an inter-dependent relationship between obesity and OSA persisted. In addition to age and BMI, several inflammatory markers helped to precisely predict surgical cure.

TLRs and RAGE are elevated in carotid plaques from patients with moderate-to-severe obstructive sleep apnea syndrome

Background

There is growing evidence that obstructive sleep apnea (OSA) promotes vascular endothelial dysfunction and atherogenesis. Pathways that mediate this pathology may include Toll-like receptors (TLRs) and receptor for advanced glycation end products (RAGE) which play a significant role in proinflammatory processes. The aim of this study was to measure the expression of the above-mentioned receptors in relation to OSA severity in carotid plaques obtained during open endarterectomy.

Methods

This prospective study included patients with a sleep study prior to surgery and a plaque specimen obtained during standard open endarterectomy. Immunohistochemistry of TLR2, TLR4, TLR7, TLR9, RAGE, HMGB1, and NF-κB was performed on atherosclerotic plaques from carotid arteries of patients with and without OSA.

Results

There were 46 patients (22 women, mean age 73.2 ± 1.3 years): 14 control patients, 13 with mild, 11 with moderate, and 8 with severe OSA. The expression of all TLRs and RAGE increased proportionately with increasing OSA severity. The largest differences between patients with severe OSA and no OSA were found for TLR2 (2.88 ± 0.35 vs. 1.27 ± 0.47, p < 0.001), TLR4 (2.88 ± 0.35 vs. 1.64 ± 0.5, p < 0.001), TLR9 (2.38 ± 0.52 vs. 1.45 ± 0.52, p < 0.01), and RAGE (2.5 ± 0.53 vs. 1.82 ± 0.6, p < 0.05).

Conclusion

TLR2, TLR4, TLR9, and RAGE expression was significantly increased in carotid plaques of patients with moderate-to-severe OSA when compared with control patients with no OSA and those with mild OSA. TLR and RAGE-mediated pathways may play a significant role in OSA-dependent atherogenesis.

Obstructive Sleep Apnoea Syndrome: Continuous Positive Airway Pressure Therapy for Prevention of Cardiovascular Risk

Obstructive sleep apnoea (OSA) syndrome is characterised by the presence of apnoea or obstructive hypopnoea during sleep, accompanied by hypoxia. It is estimated that the syndrome affects approximately 10% of men and 15% of women. Diagnosis and treatment rates have increased in recent years, but the condition remains undiagnosed in a high percentage of patients. Recent evidence suggests that OSA may increase the risk of cardiovascular disease. The relationship between OSA and cardiovascular disease can be explained, at least in part, by the coexistence of cardiovascular risk factors in the two pathologies, such as age, overweight, smoking and sedentary lifestyle. However, OSA has been independently associated with the risk of developing hypertension, cerebrovascular disease, ischaemic heart disease, heart failure and arrhythmias. Clinical trials that have evaluated the efficacy of continuous positive airway pressure (CPAP) treatment in primary and secondary cardiovascular prevention have not demonstrated a significant reduction in the incidence or recurrence of cardiovascular events. This article analyses the relationship between OSA and cardiovascular risk and discusses recent clinical trials on the efficacy of CPAP in primary and secondary cardiovascular prevention.

Evaluation of retinal fiber thickness and visual pathways with optic coherence tomography and pattern visual evoked potential in different clinical stages of obstructive sleep apnea syndrome

PURPOSE

To investigate the possible changes in retinal nerve fiber layer (RNFL) by optic coherence tomography and in the amplitudes and peak times (PTs) in pattern visual evoked potential (pVEP) and to compare them in obstructive sleep apnea syndrome (OSAS).

METHODS

This prospective study included patients with mild OSAS (n = 30), severe OSAS (n = 30), and 30 control subjects. All patients were assessed after obtaining the approval from our hospital's ethics committee.

RESULTS

There was no difference in age and gender between the groups (p = 0.184, p = 0.954). By analysis of variance, there was a significant difference in RNFL values among patients with mild OSAS, severe OSAS, and control for three measures of RNFL (average p = 0.044, nasal p = 0.003, inferior p = 0.027). In severe OSAS group, nasal and inferior quadrants of the RNFL were found to be thinner than the control group (p = 0.008, p = 0.031). We showed that the PT of P100 and N145 was prolonged in severe OSAS compared to the control group (p < 0.001) and that PT of P100 was prolonged in mild OSAS compared to the control group (p < 0.05). The amplitude of N75-P100 was significantly decreased in patients with both severe OSAS and mild OSAS compared to the control group (p < 0.001). Correlation of RNFL and pVEP values showed that the inferior quadrant RNFL thickness is correlated with both P100 and N145 PTs (r = 0.271*, p = 0.036 and r = 0.290*, p = 0.043, respectively) and N75-P100 amplitude (r = 0.378**, p = 0.003) in severe OSAS group.

CONCLUSIONS

In mild and severe stages of the disease, edema and inflammation were evident and VEP PT and amplitudes were affected in both groups. Furthermore, thinning in RNFL in the severe stage of the disease might be associated with higher atrophy levels and prolonged exposure to hypoxia.

Obstructive Sleep Apnea, Hypertension, and Cardiovascular Risk: Epidemiology, Pathophysiology, and Management

PURPOSE OF REVIEW

Given the rising prevalence of obstructive sleep apnea (OSA), we aimed to review the epidemiologic and pathophysiologic relationship of OSA, hypertension, and cardiovascular disease, and to summarize recent advances in the treatment of OSA.

RECENT FINDINGS

OSA is associated with an elevated risk of hypertension and cardiovascular disease. Several pathophysiologic factors contribute to the relationship between OSA and vascular risk, including neurohormonal dysregulation, endothelial dysfunction, and inflammation. While CPAP reduces blood pressure, it has not been demonstrated to reduce cardiovascular risk. The combination of CPAP and weight loss has a synergistic effect on blood pressure and several metabolic parameters. Adherence to CPAP is poor across studies, potentially contributing to the attenuation of perceived cardiovascular benefit from CPAP therapy. A greater emphasis on adherence to CPAP and the combination of CPAP and weight loss are central to reducing cardiovascular risk among individuals with OSA.

Treatment of obstructive sleep apnea with CPAP improves chronic inflammation measured by neutrophil-to-lymphocyte ratio

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is associated with chronic inflammation likely triggered by nocturnal, intermittent hypoxemia and increased adrenergic tone. The neutrophil-to-lymphocyte ratio (NLR) was recently described as a measure of subclinical systemic inflammation. Studies on the effect of continuous positive airway pressure (CPAP) therapy in OSA on subclinical inflammation measured by NLR are lacking. We hypothesize that NLR levels would improve as chronic inflammation diminishes in patients with OSA treated with CPAP.

METHODS

We retrospectively reviewed patients in whom OSA was diagnosed and who were treated with CPAP therapy. Complete blood count (CBC) were obtained pretreatment and posttreatment for calculation of NLR, which was calculated by dividing the number of neutrophils by the number of lymphocytes. Patients with conditions known to affect NLR such as chronic infections, inflammatory diseases, active cardiovascular disease, and malignancies were excluded from the study. CPAP adherence downloads were obtained for all patients.

RESULTS

Out of 184 patients in whom OSA was diagnosed and who were treated with CPAP, 109 met our study criteria, including baseline polysomnogram, baseline and posttreatment CBC, and available adherence download. We compared the NLR before and after treatment with CPAP. There was a significant difference in NLR before and after treatment with CPAP (P < .0001). There was also a significant difference in apnea-hypopnea index before and after treatment (P < .0001). We also assessed the relationship between CPAP adherence (percentage of days used for > 4 hours) and the change in NLR. NLR decreased significantly in both the adherent (CPAP use ≥ 70% of days; P = .014) and nonadherent groups (CPAP use < 70% of days; P = .0003). Finally, we noticed a significant direct correlation between CPAP adherence beyond 70% and the change in NLR (ΔNLR) (P = .046) in patients who had ≥ 70% adherence with CPAP, which was not observed in patients with < 70% adherence.

CONCLUSIONS

The NLR may be a useful marker for monitoring improvement, as CPAP had a desirable effect on the chronic inflammation induced by OSA when measured by NLR in this study. Our results specifically suggest that the NLR values decrease significantly in patients using CPAP regardless of adherence, but with a more direct relationship in those who use it beyond 70% of days, at least 4 hours a day.

Chronic Insomnia Is Associated with Higher Circulating Interleukin-8 in Patients with Atherosclerotic Cerebral Small Vessel Disease

OBJECTIVE

Chronic inflammatory responses and leukocyte infiltration are classical pathological features of cerebral small vessel disease (CSVD). To date, limited evidence of a relationship between chronic insomnia and inflammatory responses in patients with CSVD has been uncovered. The purpose of the present study was to investigate the potential relationship between chronic insomnia and pro-inflammatory cytokine levels in patients with atherosclerotic CSVD (A-CSVD).

METHODS

In total, 76 A-CSVD patients with or without chronic insomnia (CI) confirmed using magnetic resonance (MR) were prospectively recruited. Overnight polysomnography (PSG) was performed and serum levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, IL-17A, IL-8, and IL-12 assessed. Cytokine levels were compared between CSVD+CI (study group) and CSVD without CI (control group) patients, and the correlations between PSG parameters and cytokine levels were explored in all patients via multiple linear regression analyses.

RESULTS

The serum IL-8 level of the study group (12.3±4.4 pg/mL) was significantly higher than that of the control group (7.5±2.2 pg/mL; P<0.05). PSG measurements showed that patients in the study group had significantly higher sleep onset latency (SOL), arousal index (ArI) and wake after sleep onset (WASO) as well as lower total sleep time (TST), sleep efficiency (SE) and stage 3 NREM sleep (N-3) ratio, compared with the control group (P<0.05). Multiple linear regression analyses led to the identification of ArI (β=0.026, P<0.05) and TST (β=-0.054, P<0.05) as significant positive and negative predictors of the IL-8 level, respectively.

CONCLUSION

Chronic insomnia, in particular, sleep fragmentation and short sleep duration, may be involved in promotion of serum IL-8 expression in patients with atherosclerotic CSVD.

Association between Upper-airway Surgery and Ameliorative Risk Markers of Endothelial Function in Obstructive Sleep Apnea

The objective of our study was to evaluate the effects of upper-airway surgery on improvement of endothelial function-related markers in patients with obstructive sleep apnea (OSA). Subjects with moderate to severe OSA who underwent upper-airway surgery, with a follow-up duration of at least 6 months, were included. Pre- and postoperative polysomnographic variables and endothelial function-related markers were compared. Subgroup and correlation analyses were conducted to find possible indicators for better endothelial function-related markers after upper-airway surgery. In total, 44 patients with OSA were included. The mean follow-up duration was 1.72 ± 0.92 years. Serum VEGFA [-20.29 (CI: -35.27, -5.31), p < 0.05], Ang2 [-0.06 (CI: -0.16, 0.03), p < 0.05], E-selectin [-7.21 (CI: -11.01, -3.41), p < 0.001], VWF [-58.83 (CI: -103.93, -13.73), p < 0.05], VWFCP [-33.52 (CI: -66.34, -0.70), p < 0.05], and TM [-0.06 (CI: -0.09, -0.03), p < 0.05] were significantly lower after upper-airway surgery. However, other risk markers of endothelial function, such as Ang1, ICAM1, VEGFR1, and VCAM, did not change significantly. Correlations between improved endothelial function-related markers and ameliorated oxyhemoglobin saturation and glucolipid metabolism were established. Upper-airway surgery might be associated with an improvement in endothelial function in patients with OSA. These changes may be associated with improved oxygen saturation after upper-airway surgery.

Severe Obstructive Sleep Apnea Is Associated with Alterations in the Nasal Microbiome and an Increase in Inflammation

RATIONALE

Obstructive sleep apnea (OSA) is associated with recurrent obstruction, subepithelial edema, and airway inflammation. The resultant inflammation may influence or be influenced by the nasal microbiome.

OBJECTIVES

To evaluate whether the composition of the nasal microbiota is associated with obstructive sleep apnea and inflammatory biomarkers.

METHODS

Two large cohorts were used: 1) a discovery cohort of 472 subjects from the WTCSNORE (Seated, Supine and Post-Decongestion Nasal Resistance in World Trade Center Rescue and Recovery Workers) cohort, and 2) a validation cohort of 93 subjects rom the Zaragoza Sleep cohort. Sleep apnea was diagnosed using home sleep tests. Nasal lavages were obtained from cohort subjects to measure: 1) microbiome composition (based on 16S rRNA gene sequencing), and 2) biomarkers for inflammation (inflammatory cells, IL-8, and IL-6). Longitudinal 3-month samples were obtained in the validation cohort, including after continuous positive airway pressure treatment when indicated.

MEASUREMENTS AND MAIN RESULTS

In both cohorts, we identified that: 1) severity of OSA correlated with differences in microbiome diversity and composition; 2) the nasal microbiome of subjects with severe OSA were enriched with Streptococcus, Prevotella, and Veillonella; and 3) the nasal microbiome differences were associated with inflammatory biomarkers. Network analysis identified clusters of cooccurring microbes that defined communities. Several common oral commensals (e.g., Streptococcus, Rothia, Veillonella, and Fusobacterium) correlated with apnea-hypopnea index. Three months of treatment with continuous positive airway pressure did not change the composition of the nasal microbiota.

CONCLUSIONS

We demonstrate that the presence of an altered microbiome in severe OSA is associated with inflammatory markers. Further experimental approaches to explore causal links are needed.

Correlation of serum meteorin-like concentration with the presence and severity of obstructive sleep apnoea syndrome

Objective

Inflammatory processes that occur in subjects with obstructive sleep apnoea syndrome may contribute to progressive atherosclerosis and increased cardiovascular and cerebrovascular morbidity. Meteorin-like protein, which is also known as subfatin, is transcribed similarly to meteorin protein. Meteorin-like alleviates skeletal muscle inflammation. We aimed to investigate the serum meteorin-like status of obstructive sleep apnoea syndrome subjects and determine the potential link between serum meteorin-like concentration with the presence and severity of obstructive sleep apnoea syndrome.

Methods

The obstructive sleep apnoea syndrome group was composed of 207 obstructive sleep apnoea syndrome subjects diagnosed via polysomnography. A total of 106 healthy volunteers without clinical symptoms of obstructive sleep apnoea syndrome were recruited as the control group. Blood samples were obtained from all subjects to evaluate the serum meteorin-like concentrations via enzyme-linked immunosorbent assay method.

Results

Decreased serum meteorin-like concentration was found in obstructive sleep apnoea syndrome subjects compared with the controls. Serum meteorin-like concentration was associated with a reduced OR for having obstructive sleep apnoea syndrome (OR 0.97, 95% CI 0.961 to 0.98; P < 0.001). Severe obstructive sleep apnoea syndrome subjects showed significantly lower meteorin-like concentration compared with mild and moderate cases. Moderate subjects exhibited decreased serum meteorin-like concentration compared with mild cases. Pearson correlation analysis revealed that serum meteorin-like concentration was negatively correlated with obstructive sleep apnoea syndrome severity. Serum meteorin-like concentration negatively correlated with body mass index, low-density lipoprotein cholesterol, apnoea–hypopnea index, number of arousals, hypopnoea and apnoea in subjects with obstructive sleep apnoea syndrome.

Conclusion

Serum meteorin-like concentration is inversely correlated with the presence and severity of obstructive sleep apnoea syndrome.

The serum YKL-40 level is a potential biomarker for OSAHS: a systematic review and meta-analysis

PURPOSE

Several studies have reported that serum YKL-40 level was elevated in patients with obstructive sleep apnea hypopnea syndrome (OSAHS). However, most of these studies had relatively small sample sizes and the results were inconsistent. Therefore, a meta-analysis was conducted to determine the potential role of serum YKL-40 level in OSAHS.

METHODS

A systematic literature search was performed in several databases to identify eligible studies involving the relationship between serum YKL-40 level and OSAHS. The standardized mean difference (SMD) with its 95% confidence interval (CI) was calculated to determine the effect sizes.

RESULTS

Five eligible articles were extracted in this meta-analysis. The pooled results demonstrated that the serum YKL-40 level was significantly higher in OSAHS patients compared with their non-OSAHS controls (SMD 1.03, 95% CI 0.46, 1.59, I² = 87%, P = 0.0004). The subgroup analysis showed that Asian (SMD 1.81, 95% CI 1.41, 2.21, I² = 0%, P < 0.00001) and Caucasian (SMD 0.67, 95% CI 0.39, 0.96, I² = 0%, P < 0.00001) patients with OSAHS had higher serum YKL-40 levels than their non-OSAHS controls. YKL-40 level in serum was increased in OSAHS patients with BMI < 28 (SMD 1.81, 95% CI 1.41, 2.21, I² = 0%, P < 0.00001), as well as in patients with BMI ≥ 28 (SMD 0.57, 95% CI 0.33, 0.81, I² = 0%, P < 0.00001). In addition, OSAHS patients with cardiac complications had a higher serum YKL-40 level compared with those patients without cardiac complications (SMD 0.80, 95% CI 0.32, 1.28, I² = 67%, P = 0.001).

CONCLUSIONS

This study indicates that OSAHS patients have higher serum YKL-40 level, which may serve as a potential biomarker for OSAHS diagnosis and monitoring.

Insufficiency of positive airway pressure treatment on increased mean platelet volume: a prospective controlled study in patients with obstructive sleep apnea syndrome

BACKGROUND

To analyze the association between obstructive sleep apnea syndrome (OSAS) and some hematological variables such as mean platelet volume (MPV), platelet distribution width (PDW), and the impact of positive airway pressure (PAP) treatment on these parameters.

METHODS

The participants of the present prospective study consist of 36 OSAS patients diagnosed with polysomnography and recommended PAP treatment and 30 healthy members as the control group. Complete blood analyses were conducted to the patient group twice; before the initiation of the PAP treatment and 1 month after regular PAP use. The control group was administered a complete blood analyses only once. Patient and control group were compared in terms of various parameters such as MPV, PDW, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), white blood cell (WBC) values, and platelet counts.

RESULTS

MPV value of the patient group was before and after PAP treatment significantly higher than the control group (respectively; Z = 2.246; p = 0.025, and Z = 2.033; p = 0.042). However, there were no statistically significant differences in the values before and after PAP treatment in the patient group (Z = 0.727; p = 0.467). In terms of platelet numbers and PDW values, no significant differences were determined (p > 0.05).

CONCLUSION

MPV value was significantly elevated in OSAS patients. However, the 1 month of PAP treatment was insufficient in decreasing elevated MPV values.

Exposure to intermittent hypoxia inhibits allergic airway inflammation in a murine model of asthma

PURPOSE

Obesity increases the severity of asthma, and patients with severe asthma are often complicated with obstructive sleep apnea syndrome (OSAS), a concomitant disease of obesity. We investigated whether intermittent hypoxia (IH), which is a physiological feature of OSAS, modifies allergic airway inflammation in a murine model of asthma.

METHODS

Balb/c mice were sensitized by ovalbumin (OVA) intraperitoneally twice (days 1 and 14) and challenged with intranasal OVA three times (days 21, 22, and 23). The mice were exposed to IH either from days 1 to 24 (long exposure) or only from days 21 to 24 (short exposure). The impact of IH exposure to allergic airway inflammation was investigated using these mice models by histologic, morphometric, and molecular techniques. Additionally, the airway responsiveness to acetylcholine was also assessed.

RESULTS

OVA-sensitized and OVA-challenged mice exposed to room air (RA) showed increased total cell and eosinophil numbers in the BALF. The levels of interleukin (IL)-5 and IL-13 in the BALF also increased and goblet cell metaplasia was induced. In contrast, both long and short exposure to IH inhibited the increased total cell and eosinophil numbers. The levels of IL-5 and IL-13 in the BALF also decreased on exposure to IH. Moreover, the goblet cell hyperplasia and airway hyperresponsiveness were significantly reduced in mice exposed to IH compared to those exposed to RA.

CONCLUSIONS

These results suggest that IH may not deteriorate the asthmatic condition in a murine model of asthma.

Role of Obstructive Sleep Apnea in Cognitive Impairment

Obstructive sleep apnea (OSA) is a prevalent sleep related breathing disorder characterized by repetitive collapse of the upper airways leading to intermittent hypoxia and sleep disruption. Clinically relevant neurocognitive, metabolic and cardiovascular disease often occurs in OSA. Systemic hypertension, coronary artery disease, type 2 diabetes mellitus, cerebral vascular infarctions and atrial fibrillation are among the most often cited conditions with causal connections to OSA. Emerging science suggest that untreated and undertreated OSA increases the risk of developing cognitive impairment, including vascular dementia and neurodegenerative disorders, like Alzheimer’s disease. As with OSA, cardiovascular disease and type 2 diabetes mellitus, the incidence of dementia increases with age. Given our rapidly aging population, dementia prevalence will significantly increase. The aim of this treatise is to review current literature linking OSA to dementia and explore putative mechanisms by which OSA might facilitate the development and progression of dementia.

Decreased Levels of Anti-Aging Klotho in Obstructive Sleep Apnea

The klotho protein is secreted primarily by the kidneys. It is responsible for phosphate homeostasis and has an anti-aging, anti-inflammatory, and anti-oxidative stress role. Obstructive sleep apnea (OSA) is associated with an enhanced systemic inflammation and oxidative stress, but mechanisms that regulate these processes are poorly understood. The aim of the study was to investigate the plasma levels of klotho in OSA. Twenty-one previously untreated patients with OSA (56 ± 13 years, 12 males) and 41 non-OSA control volunteers (48 ± 16 years, 8 males) participated in the study. Medical history has been taken; participants filled out the Epworth Sleepiness Scale. C-reactive protein and renal function, glucose and lipid profile measurements were performed in sera; klotho was determined in citrate-treated plasma samples. Levels of plasma klotho were decreased in OSA (519.1 ± 164.9 pg/mL) versus controls (700.8 ± 431.4 pg/mL, p = 0.02). Reduced klotho concentrations were associated with markers of overnight hypoxemia determined with O₂ desaturation index (r = -0.31, p = 0.01), percentage of sleep time spent with saturation <90% (r = -0.41, p < 0.01), and minimal saturation during sleep (r = 0.33, p = 0.01). Interestingly, there was no relationship with apnea-hypopnea index, total sleep time, or arousal index (all p > 0.05). Significant association was also found between low plasma klotho levels and the presence of hypertension (p < 0.05). Our results suggest that chronic intermittent hypoxia reduces the levels of klotho in OSA, which may contribute to the development of hypertension. Decreased klotho levels may play a role in enhanced systemic inflammation in OSA and may be a future target for drug development.

Association study of genetic variations of inflammatory biomarkers with susceptibility and severity of obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) increases health risks of cardiovascular disease and stroke. Both genetic factors and environmental exposures contribute to the occurrence of OSA. The purpose of this study was to determine the role of four functional inflammatory single nucleotide polymorphisms (SNPs) (VWF rs1063856, IL-6 rs1800796, TNF rs1800629, and CRP rs2794521) in the susceptibility and severity of OSA.

METHODS

A case-control study of OSA among Chinese population was conducted. Genotyping was performed using ABI TaqMan SNP genotyping technique.

RESULTS

We found VWF rs1063856 (OR = 1.50, 95% CIs = 1.10-2.04; p = 0.010), IL-6 rs1800796 (OR = 1.32, 95% CIs = 1.11-1.56; p = 0.002), TNF rs1800629 (OR = 1.44, 95% CIs = 1.13-1.83; p = 0.003), and CRP rs2794521 (OR = 1.27, 95% CIs = 1.04-1.55; p = 0.021) were all significantly associated with increased susceptibility of OSA, while VWF rs1063856 (OR = 1.75, 95% CIs = 1.18-2.62; p = 0.006), IL-6 rs1800796 (OR = 1.39, 95% CIs = 1.10-1.76; p = 0.006) were associated with the severity of OSA.

CONCLUSIONS

Our study indicated that functional variants of inflammatory biomarkers could cause the occurrence of OSA and influence the severity of OSA. These findings further support that inflammatory cytokines were closely related to the occurrence and development of OSA.

Serum S100A12 and S100B proteins are independent predictors of the presence and severity of obstructive sleep apnea

Background/aim

Obstructive sleep apnea (OSA) is associated with serious cardiometabolic risks. Early diagnosis and treatment compliance are important. For this purpose, research is being carried out on biomarkers associated with the pathogenesis of the disease. We aimed to investigate whether serum S100A12 and S100B proteins could be used as biochemical markers in OSA patients to determine disease presence and severity.

Materials and methods

A total of 60 (16 women, 44 men) patients with OSA and 50 (20 women, 30 men) controls were enrolled in this cross-sectional study. Each subject included in the study underwent full-night polysomnography (PSG). The presence and severity of OSA was assessed with the apnea–hypopnea index (AHI). In the OSA group, 17 cases were mild, 18 were moderate, and 25 were severe.The serum levels of S100A12 and S100B were measured using the enzyme-linked immunosorbent assay (ELISA) technique. These protein levels were compared using Student’s t-test in the patient and control groups. Spearman’s rho correlation coefficients and corresponding P-values were calculated to determine the correlations between these protein levels and polysomnographic parameters. For evaluating the association between OSA and biomarkers, as well as possible confounding factors with S100A12 and S100B, we employed multiple linear regression analyses for the patients with OSA.

Results

Serum levels of S100A12 and S100B were higher in patients than those in controls (P = 0.01 and P = 0.005, respectively), and a significant correlation was determined between S100A12 and S100B values and AHI (P = 0.0001; P = 0.0001), sleep time with SpO2 < 90% (P = 0.032; P = 0.01), minimum SpO2 during sleep (P = 0.019; P = 0.007), and oxygen desaturation index (ODI) (P = 0.001; P = 0.0001). In the linear regression analysis, AHI was independently related with both S100A12 (P < 0.0001) and S100B (P = 0.011). Receiving operating curves (ROC) identified patients with OSA: AUC for S100A12 = 0.643; AUC for S100B = 0.655 (P < 0.05).

Conclusion

Serum levels of S100B and S100A proteins have high diagnostic performance in OSA and are independent predictors of OSA presence and severity.

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.

Proliferative Pathways of Vascular Smooth Muscle Cells in Response to Intermittent Hypoxia

Obstructive sleep apnea (OSA) is characterized by intermittent hypoxia (IH) and is a risk factor for cardiovascular diseases (e.g., atherosclerosis) and chronic inflammatory diseases (CID). The excessive proliferation of vascular smooth muscle cells (VSMCs) plays a pivotal role in the progression of atherosclerosis. Hypoxia-inducible factor-1 and nuclear factor-κB are thought to be the main factors involved in responses to IH and in regulating adaptations or inflammation pathways, however, further evidence is needed to demonstrate the underlying mechanisms of this process in VSMCs. Furthermore, few studies of IH have examined smooth muscle cell responses. Our previous studies demonstrated that increased interleukin (IL)-6, epidermal growth factor family ligands, and erbB2 receptor, some of which amplify inflammation and, consequently, induce CID, were induced by IH and were involved in the proliferation of VSMCs. Since IH increased IL-6 and epiregulin expression in VSMCs, the same phenomenon may also occur in other smooth muscle cells, and, consequently, may be related to the incidence or progression of several diseases. In the present review, we describe how IH can induce the excessive proliferation of VSMCs and we develop the suggestion that other CID may be related to the effects of IH on other smooth muscle cells.

Is C-reactive protein elevated in obstructive sleep apnea? a systematic review and meta-analysis

Purpose: This study examined whether circulating C-reactive protein (CRP) is elevated in obstructive sleep apnoea (OSA) independent of the confounding effects of comorbidities, smoking, body mass index (BMI), age and gender. Methods: A systematic review of the literature was performed using PubMed, Embase and Cochrane databases from 1 January 1997 to 1 November 2017 using the key words obstructive sleep apnoea and C-Reactive protein to identify full text English language studies that compared CRP in adult non-smoking OSA participants without comorbidities and adult healthy non-smoking control participants matched for BMI, age and gender. Data from eligible studies were subjected to meta-analysis using RevMan version 5.3. Results: Five studies (219 OSA participants, 116 controls) met the selection criteria. The total standard mean difference for circulating high sensitivity CRP was 0.61 mg/dL higher in OSA participants than in control participants (confidence interval: 0.38 to 0.84, p < 0.00001), with low between-studies heterogeneity (df = 7, p = 0.16, I² = 33%) and minimal evidence of publication bias. Conclusions: CRP levels in non-smoking OSA participants without comorbidities were increased relative to levels in healthy matched non-smoking control participants, suggesting that pharyngeal or systemic inflammatory effects attributable to OSA may elevate CRP.

IL-33 Mediated Inflammation in Chronic Respiratory Diseases-Understanding the Role of the Member of IL-1 Superfamily

Interleukin 33 (IL-33) is an alarmin cytokine from the IL-1 family. IL-33 is localized in the nucleus and acts there as a gene regulator. Following injury, stress or cell death, it is released from the nucleus, and exerts its pro-inflammatory biological functions via the transmembrane form of the ST2 receptor, which is present mainly as attached to immune cells. In recent years, IL-33 became a focus of many studies due to its possible role in inflammatory disorders. Among respiratory disorders, the contribution of IL-33 to the development of asthma, in particular, has been most identified. Increased level of IL-33 in lung epithelial cells and blood serum has been observed in asthma patients. The IL-33/ST2 interaction activated the Th2 mediated immune response and further production of many pro-inflammatory cytokines. Single nucleotide polymorphisms in the IL-33 gene cause a predisposition to the development of asthma. Similarly, in chronic pulmonary obstructive disease (COPD), both increased expression of IL-33 and the ST2 receptor has been observed. Interestingly, cigarette smoke, a key inducer of COPD, not only activates IL-33 production by epithelial and endothelial cells, but also induces the expression of IL-33 in peripheral blood mononuclear cells. Knowledge regarding its contribution in other respiratory disorders, such as obstructive sleep apnea, remains greatly limited. Recently it was shown that IL-33 is one of the inflammatory mediators by which levels in blood serum are increased in OSA patients, compared to healthy control patients. This mini review summarizes current knowledge on IL-33 involvement in chosen chronic respiratory disorders and proposes this interleukin as a possible link in the pathogenesis of these diseases.

Enhanced interleukin-8 production in mononuclear cells in severe pediatric obstructive sleep apnea

Background

Obstructive sleep apnea (OSA) is a risk factor for cardiovascular disease, metabolic disorders, and cognitive dysfunction. Current thinking links chronic intermittent hypoxia (CIH) with oxidative stress and systemic inflammation. However, the sequence of events leading to the morbidities associated with OSA is poorly understood in children. Monocytes are known to be altered by chronic hypoxia. Thus in this prospective study, we investigated inflammatory cytokine profiles from cultures of peripheral blood mononuclear cells (PBMC) obtained from children with severe OSA and sleep-related CIH.

Methods

Ten children with OSA (cases) and 5 age-matched children without OSA (controls) were recruited for study. Samples of plasma and PBMC were obtained before and after adenotonsillectomy. The levels of the inflammatory cytokines, interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-12p70, and tumor necrosis factor-α (TNFα), were measured in both plasma and ex vivo culture supernatants of PBMC incubated with lipopolysaccharide (LPS) using the cytometric bead assay.

Results

Upon activation of PBMC by LPS, the levels of IL-8 in the culture supernatants from cases were threefold higher than in controls. The levels of the other cytokines including IL-1β, IL-6, and TNFα, in culture supernatant of PBMC from cases showed no difference from controls; nor were there significant differences in plasma cytokine levels.

Conclusion

We speculate that in young children with sleep-related CIH, an enhanced production capacity of IL-8 precedes the development of systemic inflammatory markers. Future work should evaluate IL-8 production capacity as a potential biomarker for OSA severity.

[The problem of obstructive sleep apnea syndrome in asthmatic patients]

Asthma and obstructive sleep apnea syndrome (OSAS) are one of the most common chronic respiratory diseases. These have common risk factors that include obesity, gastroesophageal reflux disease (GERD) and impaired nasal breathing (allergic rhinitis, sinusitis). At the same time, experimental evidence demonstrates common pathophysiological mechanisms of these diseases, such as involvement in the process of the respiratory tract, a systemic inflammatory response, and implementation of neuromechanical reflexes. Thus, there is an obvious synergism between these conditions, which affects symptoms, response to therapy, and prognosis. The available data allow discussion on whether there is a need to identify and treat OSAS in asthmatic patients. By keeping in mind the high incidence of OSAS in patients with severe asthma, it may be suggested that treatment for OSAS can reduce the number of exacerbations, improve the quality of life, and decline the number of obstinate asthma cases. It is very important for general practitioners to assess risk factors, such as body weight, nasal stuffiness, and GERD, and to utilize screening tools for more efficient use of healthcare resources. Considering the known positive effects of CPAP therapy in short-term studies, future investigations should focus on the impact of CPAP therapy on asthma symptoms in the long-term, as well as on the effects of asthma drugs on the course of OSAS.

Severe Obstructive Sleep Apnea With Imaged Carotid Plaque Is Significantly Associated With Systemic Inflammation

PURPOSE

Persons with obstructive sleep apnea (OSA) are at heightened risk of myocardial infarction (MI) and stroke caused by adiposity and intermittent hypoxia, which provoke proinflammatory cytokines to induce systemic and vascular inflammation, resulting in endothelial dysfunction and development of atherosclerotic plaque. This study compared levels of systemic inflammation, as indexed by the neutrophil-to-lymphocyte ratio (NLR), between groups of patients with severe OSA with and without carotid artery calcified plaque (CACP⁺ and CACP^-, respectively) on their panoramic image (PI).

MATERIALS AND METHODS

This study had a retrospective cross-sectional study design. Medical records and PIs of men with severe OSA treated by the dental service (January 1, 2017 to December 31, 2017) were reviewed. The predictor variable was the presence or absence of CACP on PIs and the outcome variable was NLR. The t test was used to analyze differences in mean NLRs between groups. Atherogenic risk factors (age, body mass index, hypertension, and diabetes) were assessed for independence by descriptive and logistic regression analyses. Significance set at .05 for all tests.

RESULTS

The study group (n = 39) of patients with CACP⁺ (mean age, 63 ± 7.4 yr) showed a mean NLR of 3.09 ± 1.42. The control group (n = 46) of patients with CACP^- (mean age, 62 ± 6.8 yr) showed a mean NLR of 2.10 ± 0.58. The difference between groups was significant (P < .001). Logistic regression for NLR and CACP failed to show meaningful correlations with covariates.

CONCLUSION

Older men with severe OSA and carotid atheromas on PIs show substantially greater systemic inflammation measured by NLRs. The combination of severe OSA, atheroma formation, and markedly increased NLR suggests a higher risk of MI and stroke and greater need for cardiovascular and cerebrovascular evaluation.