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

Serum biomarkers of inflammation and adiposity in the LABS cohort: associations with metabolic disease and surgical outcomes

BACKGROUND

The utility of serum biomarkers related to inflammation and adiposity as predictors of metabolic disease prevalence and outcomes after bariatric surgery are not well-defined.

METHODS

Associations between pre- and post-operative serum levels of four biomarkers (C-reactive protein (CRP), cystatin C (CC), leptin, and ghrelin) with baseline measures of adiposity and metabolic disease prevalence (asthma, diabetes, sleep apnea), and weight loss and metabolic disease remission after bariatric surgery were studied in the Longitudinal Assessment of Bariatric Surgery (LABS) cohort.

RESULTS

Baseline CRP levels were positively associated with the odds of asthma but not diabetes or sleep apnea; baseline CC levels were positively associated with asthma, diabetes, and sleep apnea; baseline leptin levels were positively associated with asthma and negatively associated with diabetes and sleep apnea; baseline ghrelin levels were negatively associated with diabetes and sleep apnea. Increased weight loss was associated with increased baseline levels of leptin and CRP and decreased baseline levels of CC. Remission of diabetes and asthma was not associated with baseline levels of any biomarker. A higher likelihood of asthma remission was associated with a greater decrease in leptin levels, and a higher likelihood of diabetes remission was predicted by a lesser decrease in CC. Bariatric surgery was associated with decreased post-operative CC, CRP, and leptin levels, and increased post-operative ghrelin levels.

CONCLUSION

This is the largest study to date of serum biomarkers of inflammation and adiposity in a bariatric surgery cohort. Biomarker levels correlate with metabolic disease prevalence prior to bariatric surgery, and with weight loss but not metabolic disease remission after surgery. Bariatric surgery regulates serum biomarker levels in a manner consistent with anti-inflammatory and compensatory orexigenic effects. These data contribute to our understanding of the mechanisms underlying the biologic effects of bariatric surgery.

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.

Impaired Glucose Metabolisms of Patients with Obstructive Sleep Apnea and Type 2 Diabetes

AIMS

Obstructive sleep apnea (OSA) is a very common disorder which is associated with metabolic comorbidities. The aims of this study were to analyze clinical data of patients with OSA and evaluate influence of sleep-disordered breathing on glycometabolism and its underlying mechanisms.

METHODS

We designed a cross-sectional study involving 53 OSA patients in The First Hospital of Jilin University from March 2015 to March 2016. They underwent a full-night polysomnography, measurement of fasting blood glucose and blood lipid profiles. Besides, we chose 20 individuals with type 2 diabetes mellitus (T2DM) as a subgroup for an in-depth study. This group additionally underwent a steamed bread meal test and measurement of HbA1c, C-reactive protein, tumor necrosis factor-α, interleukin 6, morning plasma cortisol, and growth hormone.

RESULTS

The two groups which with or without T2DM showed no significant differences in baseline characteristics. As for OSA patients with T2DM, the severe OSA group had higher homeostasis model assessment of insulin resistance (HOMA-IR) (P = 0.013) than the mild-to-moderate OSA group, whereas had lower morning plasma cortisol levels (P = 0.005) than the mild-to-moderate OSA group. AHI was positive correlated with HOMA-IR (r = 0.523, P = 0.018), yet negative correlated with morning plasma cortisol (r = -0.694, P = 0.001). However, nadir SpO2 was positive correlated with morning plasma cortisol (r s = 0.646, P = 0.002), while negative correlated with HOMA-IR (r s = -0.489, P = 0.029).

CONCLUSIONS

Our study showed that sleep-disordered breathing exerted negative influence on glucose metabolisms. The impairment of hypothalamic-pituitary-adrenal axis activity may be one of the underlying mechanisms of the glycometabolic dysfunctions in OSA with T2DM patients.

Nonallergic Triggers and Comorbidities in Asthma Exacerbations and Disease Severity

Asthma triggers are exogenous or endogenous factors that could worsen asthma acutely to cause an exacerbation, or perpetuate chronic symptoms and airflow limitation. Because it is well known that recent asthma exacerbations and poor symptom control are strong predictors of future disease activity, it is not surprising that the number of (allergic or nonallergic) asthma triggers in the environment correlates with the disease-related quality of life. There is a need to identify and avoid specific triggers as the centerpiece of disease management, especially in those with heightened sensitivity to certain factors.

Biomarkers of dementia in obstructive sleep apnea

Epidemiologic and mechanistic evidence is increasingly supporting the notion that obstructive sleep apnea is a risk factor for dementia. Hence, the identification of patients at risk of cognitive decline due to obstructive sleep apnea may significantly improve preventive strategies and treatment decision-making. Cerebrospinal fluid and blood biomarkers obtained through genomic, proteomic and metabolomic approaches are improving the ability to predict incident dementia. Therefore, fluid biomarkers have the potential to predict vulnerability to neurodegeneration in individuals with obstructive sleep apnea, as well as deepen our understanding of pathophysiological processes linking obstructive sleep apnea and dementia. Many fluid biomarkers linked to Alzheimer's disease and vascular dementia show abnormal levels in individuals with obstructive sleep apnea, suggesting that these conditions share common underlying mechanisms, including amyloid and tau protein neuropathology, inflammation, oxidative stress, and metabolic disturbances. Markers of these processes include amyloid-β, tau proteins, inflammatory cytokines, acute-phase proteins, antioxydants and oxidized products, homocysteine and clusterin (apolipoprotein J). Thus, these biomarkers may have the ability to identify adults with obstructive sleep apnea at high risk of dementia and provide an opportunity for therapeutic intervention. Large cohort studies are necessary to establish a specific fluid biomarker panel linking obstructive sleep apnea to dementia risk.

Cardiac rhythm disorders in obstructive sleep apnea

Obstructive sleep apnea (OSA) is common among patients with cardiac rhythm disorders. OSA may contribute to arrhythmias due to acute mechanisms, such as generation of negative intrathoracic pressure during futile efforts to breath, intermittent hypoxia, and surges in sympathetic activity. In addition, OSA may lead to heart remodeling and increases arrhythmia susceptibility. Atrial distension and remodeling, that has been shown to be associated with OSA, is a well-known anatomical substrate for atrial fibrillation (AF). AF is the arrhythmia most commonly described in patients with OSA. Several observational studies have shown that the treatment of OSA with continuous positive airway pressure (CPAP) reduces recurrence of AF after electrical cardioversion and catheter ablation. There is also evidence that nocturnal hypoxemia, a hallmark of OSA, predicts sudden cardiac death (SCD) independently of well-established cardiovascular risk factors. Among patients with an implantable cardiac defibrillator, those with OSA have a higher risk of receiving treatment for life-threatening arrhythmias. Nocturnal hypoxemia may also increase vagal tone, which increases susceptibility to bradycardic and conduction rhythm disorders that have also been described in patients with OSA. In conclusion, there are several biological pathways linking OSA and increased cardiac arrhythmogenesis propensity. However, the independent association is derived from observational studies and the direction of the association still needs clarification due to the lack of large clinical trials. This review focuses on the current scientific evidence linking OSA to cardiac rhythm disorders and point out future directions.

Hematological indices as simple, inexpensive and practical severity markers of obstructive sleep apnea syndrome: a meta-analysis

Background

Clinical detection of inflammatory markers is useful to assess the degree of nocturnal hypoxia and predict the presence of complications in obstructive sleep apnea syndrome (OSAS) patients. Nowadays, some researchers proposed that hematological parameters could be substituted for novel disease-specific biochemical markers (such as C-reactive protein) because they were comparatively cheap, simple and practical. But there was a contradiction whether the hematological parameters were positively correlated with the OSAS severity.

Methods

Medical databases were searched included PubMed, Web of Science, Scopus, Cochrane Library, Clinical Trial, Embase and Google Scholar (up to March 29, 2018). We used weighted mean differences (WMDs) with 95% confidence intervals (CIs) from random-effects model.

Results

Seventeen studies were included in this meta-analysis and results were presented by different hematological parameters. Pooled analysis showed that OSAS was associated with a high level of WBC (white blood cell, 11 studies, 2,206 subjects, WMD: 0.58; 95% CI: 0.31 to 0.85; P<0.0001), NLR (neutrophil-to-lymphocyte ratio, 5 studies, 1416 subjects, WMD: 0.46; 95% CI: 0.13 to 0.80; P=0.007), MPV (mean platelet volume, 8 studies, 1,854 subjects, WMD: 0.63; 95% CI: 0.29 to 0.98; P=0.0004), PDW (platelet distribution width, 6 studies, 1,911 subjects, WMD: 0.76; 95% CI: 0.47 to 1.06; P<0.00001), PLR (platelet-to-lymphocyte ratio, 3 studies, 998 subjects, WMD: 21.76; 95% CI: 8.54 to 34.99; P=0.001), RDW (red cell distribution width, 5 studies, 1,701 subjects, WMD: 0.31; 95% CI: 0.11 to 0.51; P=0.002) and HCT (hematocrit, 3 studies, 662 subjects, WMD: 1.58; 95% CI: 0.52 to 2.64; P=0.003). But OSAS was associated with a low level of LYM (lymphocyte, 5 studies, 1,285 subjects, WMD: -0.27; 95% CI: -0.49 to -0.06; P=0.01). There was a gradual rising trend from mild OSAS to severe OSAS existed in all subgroups.

Conclusions

Hematological indices are comparatively Simple, Inexpensive and Practical Severity Markers of OSAS including WBC, LYM, NLR, MPV, PDW, PLR, RDW and HCT.

Obstructive sleep apnea as a risk factor for preeclampsia-eclampsia

PURPOSE

Preeclampsia-eclampsia remains one of the leading causes of maternal and perinatal morbidity and mortality. Emerging evidence suggests that obstructive sleep apnea (OSA), which has been linked to hypertension in the general population, may play role in hypertensive disorders in pregnancy, including preeclampsia-eclampsia. However, little research has been conducted in Asia (no data in Thailand) on the effects of OSA on preeclampsia-eclampsia. We aimed to examine the association between OSA and preeclampsia-eclampsia among Thai pregnant women.

METHODS

We conducted a large prospective cohort study among Thai pregnant women who were in the second trimester of singleton pregnancy. The Berlin Questionnaire was administered to evaluate the risk for OSA. Preeclampsia-eclampsia was diagnosed by standard clinical assessment. Multivariate models were applied in adjustment for confounding factors.

RESULTS

Enrolled were 1345 pregnant women. The overall prevalence of high risk for OSA was 10.1% (95% confidence intervals [CIs] 8.5-11.7), and it was significantly associated with pre-pregnancy body mass index and score on the Perceived Stress Scale. An adjusted odds ratio (OR) for preeclampsia-eclampsia in women with high risk for OSA was 2.72 (95% CI 1.33-5.57).

CONCLUSIONS

Pregnant women with high risk for OSA are at increased risks for preeclampsia-eclampsia compared to those with low risk for OSA. Our results support a role for screening for OSA by BQ during antenatal care.

Normal-tension glaucoma: Pathogenesis and genetics

Normal-tension glaucoma (NTG) is a multifactorial optic neuropathy which, similar to open-angle glaucomas, is characterized by progressive retinal ganglion cell death and glaucomatous visual field loss. The major distinction of NTG from open-angle glaucomas is that the intraocular pressure (IOP) does not exceed the normal range. Missing the major risk factor and target of therapy, the elevated IOP, NTG poses a clinical challenge. Several insightful reviews have been published on the pathophysiology of NTG describing the possible underlying mechanisms. The current literature available also suggests that a significant percentage of patients with NTG (as high as 21%) have a family history of glaucoma, indicating a genetic predisposition to the disease. These facts strengthen the indication that NTG remains an enigmatic process. The aim of this review was to summarize the vascular, mechanical and genetic components considered to be responsible for NTG development and to discuss the mechanisms through which they are involved in the pathogenesis of NTG.

[Etiopathogenesis of obstructive sleep apnoea and its consequences in the children]

The article presents the modern view of etiology of the obstructive sleep apnoea/hypopnoea syndrome (OAHSS) in the children taking into consideration the ontogenetic stage and the principal mechanisms of its formation including the short-term and long-term consequences of sleep apnoea with special reference to the pathogenetic commonness of OAHSS with endothelial dysfunction, metabolic syndrome, cardiac disorders, and systemic chronic inflammation. The role of ENT diseases in the children with obstructive sleep apnoea is discussed. The results of genetic studies of the processes influencing the formation of the risk of development of sleep apnoea/hypopnoea syndrome and its outcomes in the children are discussed.

Chronic Rhinosinusitis Is an Independent Risk Factor for OSA in World Trade Center Responders

BACKGROUND

Many respiratory conditions have been attributed to toxic dust and fume exposure in World Trade Center (WTC) rescue and recovery workers, who frequently report symptoms of OSA. We examined the prevalence of new-onset OSA and tested if the prevalence and severity of OSA are related to the presence of chronic rhinosinusitis (CRS).

METHODS

A total of 601 subjects (83% men; age, 33-87 years; BMI, 29.9 ± 5.5 kg/m²) enrolled in the WTC Health Program, excluding those with significant pre-September 11, 2001, snoring or prior CRS, underwent two nights of home sleep testing. OSA was defined as Apnea Hypopnea Index 4% ≥ 5 events/h or respiratory disturbance index of ≥ 15 events/h. CRS was assessed using nasal symptom questionnaires.

RESULTS

The prevalence of OSA was 75% (25% no OSA, 46% mild OSA, 19% moderate OSA, and 10% severe OSA), and the prevalence of CRS was 43.5%. Compared with no CRS, new and worsening CRS was a significant risk factor for OSA with an OR of 1.80 (95% CI, 1.18-2.73; P = .006) unadjusted and 1.76 (95% CI, 1.08-2.88; P = .02) after adjustment for age, BMI, sex, gastroesophageal reflux disorder, and alcohol use.

CONCLUSIONS

The high prevalence of OSA in WTC responders was not explained fully by obesity and sex. Possible mechanisms for the elevated risk of OSA in subjects with CRS include increased upper airway inflammation and/or elevated nasal/upper airway resistance, but these need confirmation.

The Association of Unreported Sleep Disturbances and Systemic Inflammation: Findings from the 2005-2008 NHANES

BACKGROUND/OBJECTIVE

Sleep apnea is associated with elevated inflammatory markers. A subgroup of patients never report sleep disturbances to their physician. The inflammatory status of this subgroup is not known. The present study aims to evaluate two inflammatory markers, C-reactive protein (CRP) and red cell distribution width (RDW), in those with unreported sleep disturbances and compares these findings to those with and without reported sleep disorders. We also investigate the utility of RDW as an inflammatory marker in sleep disorders.

METHODS

Sample includes 9,901 noninstitutionalized, civilian, nonpregnant adults from the 2005-2008 National Health and Nutrition Examination Survey, a nationally representative, cross-sectional U.S. study. Sleep questionnaire and laboratory data were used to compare inflammatory markers (CRP and RDW) in five subgroups of individuals: reporting physician-diagnosed sleep apnea, reporting another physician-diagnosed sleep disorder, reported sleep disturbance to physician with no resulting diagnosis, unreported sleep disturbance (poor sleep quality not reported to physician), and no diagnosed sleep disorder or sleep disturbance.

RESULTS

Individuals with unreported sleep disturbance had significantly higher odds of elevated RDW (>13.6%) when compared to those without a sleep disturbance in adjusted models (OR=1.33). Those with unreported sleep disturbance had significantly higher odds of elevated CRP levels (>1 mg/L) than those without sleep disturbances (OR 1.34), although the association was not significant when adjusted for obesity and other controls.

CONCLUSION

Self-identified unreported sleep disturbances are associated with significantly higher odds of elevated RDW than those without sleep disturbances. RDW may serve as a valuable indicator in identifying individuals at higher risk for sleep apnea and other sleep disorders.

Links between lower urinary tract symptoms, intermittent hypoxia and diabetes: Causes or cures?

Bothersome lower urinary tract symptoms (LUTS) manifest as urinary frequency, urgency, incontinence and incomplete bladder emptying. Existing treatments ameliorate but do not eliminate most symptoms, leading to financial and personal burdens attributable to sustained medical therapies that may last a lifetime. The purpose of this review is to highlight evidence of causal associations between LUTS and several common comorbidities, including intermittent hypoxia (IH) concomitant with obstructive sleep apnea (OSA), obesity, metabolic syndrome and type 2 diabetes. Links between these conditions, including therapies targeted to co-occurring complications that have demonstrated benefits for LUTS, suggest compelling avenues of research and also underscore critical gaps in understanding the mechanisms underlying urinary dysfunction. These gaps are prominent in the IH field, where an acknowledged link between OSA and LUTS has gone largely uninvestigated. New tools, models, or reappropriation of existing ones, especially rodent models, is required to parse the associations between IH/OSA, LUTS and obesity/diabetes and to elucidate their underlying, and potentially shared, etiologies.

Association between Obstructive Sleep Apnea and Cardiovascular Risk Factors: Variation by Age, Sex, and Race. The Multi-Ethnic Study of Atherosclerosis

RATIONALE

The association between obstructive sleep apnea (OSA) and cardiovascular disease (CVD) is complex, bidirectional, and may vary across groups. Understanding which cardiovascular risk factors vary in their relationship to OSA across population groups may improve knowledge of OSA-related CVD susceptibility.

OBJECTIVES

To better understand the heterogeneity of associations, we assessed whether associations of OSA with cardiovascular risk factors vary by age, sex, and race/ethnicity.

METHODS

We performed cross-sectional analyses of 1,344 Multi-Ethnic Study of Atherosclerosis participants who underwent overnight full polysomnography, assays of fasting blood, and assessments of cardiovascular risk factors. Risk factors considered were blood pressure, glucose/lipid concentrations, white blood cell (WBC) total and subset counts, and cystatin C. The outcome was the apnea-hypopnea index (AHI). Linear regression analyses with tests for interactions were conducted.

RESULTS

The sample had a mean age of 68 ± 9 years. Forty-seven percent of the sample was male, and 32% had moderate or severe OSA (AHI, ≥15). Multivariable adjusted analysis showed significant associations between higher AHI with lower high-density lipoprotein cholesterol and higher diastolic blood pressure and neutrophil counts. Significant interactions with demographic factors were observed. Stronger associations were shown between AHI and higher total WBC count (Pint = 0.006) and glucose concentrations (Pint = 0.006) in younger (<65 yr) than in older individuals, higher triglyceride concentrations in men than in women (Pint = 0.006), and higher total WBC (Pint = 0.07) and monocyte counts (Pint = 0.03) in African American individuals than in other racial groups.

CONCLUSIONS

In a multiethnic cohort, we found increased levels of cardiovascular risk factors in association with OSA, including elevated neutrophil counts, a marker of inflammation. Furthermore, several associations were stronger in men, younger individuals, and African American individuals, highlighting pathways for CVD risk that may explain heterogeneity in the associations between CVD and OSA across population groups.

Adropin and Inflammation Biomarker Levels in Male Patients With Obstructive Sleep Apnea: A Link With Glucose Metabolism and Sleep Parameters

STUDY OBJECTIVES

The main objectives of the study were to determine plasma adropin, systemic inflammation biomarker levels, and glucose metabolism parameters in patients with moderate and severe obstructive sleep apnea (OSA) compared to healthy controls.

METHODS

In this study, we included 50 male patients with OSA (25 moderate and 25 severe) and 25 age- and sex-matched control subjects. All subjects underwent fasting sampling of peripheral blood for laboratory analyses.

RESULTS

Adropin plasma levels were significantly lower in the severe OSA group in comparison with the moderate and control groups (4.50 ± 1.45 versus 6.55 ± 1.68 versus 8.15 ± 1.79 ng/mL, P < .001). Plasma biomarkers of systemic inflammation were significantly increased in patients with moderate OSA (interleukin [IL]-6 and tumor necrosis factor alpha [TNF-α]) and severe OSA (IL-6, TNF-α, high-sensitivity C-reactive protein) when compared with controls (P < .001). Adropin levels showed a significant negative correlation with IL-6 (r = -.419, P < .001), TNF-α (r = -.540, P < .001), fasting glucose (r = -.331, P = .004), hemoglobin A1c (r = -.438, P < .001), homeostatic model assessment insulin resistance index (r = -.213, P = .046), and polysomnographic parameters including apnea-hypopnea index (r = -.615, P < .001) and oxygen desaturation index (r = -.573, P < .001). A multivariate regression analysis showed that plasma adropin remained as a significant negative predictor of severe OSA status, when adjusted for age and body mass index and computed along with other inflammatory biomarkers in the regression model (odds ratio 0.069, 95% confidence interval 0.009-0.517, P = .009).

CONCLUSIONS

Plasma adropin concentrations significantly correlate with indices of disease severity in patients with OSA, suggesting that adropin potentially plays an important role in the complex pathophysiology of the disease.

Association of sleep disturbances with obesity, insulin resistance and the metabolic syndrome

Insufficient sleep, which has become endemic in recent years, has been variably associated with increased risk of obesity, disorders of glucose and insulin homeostasis, and the metabolic syndrome; to a lesser degree, so has excessive sleep. This review summarizes recent epidemiological and pathophysiological evidence linking sleep disturbances (primarily abnormalities of sleep duration) with obesity, insulin resistance, type 2 diabetes and the metabolic syndrome in children and adults.

Circulating Survivin Levels in Obstructive Sleep Apnoea

INTRODUCTION

Obstructive sleep apnoea (OSA) is characterised by a low-grade systemic and airway inflammation; however, the regulatory mechanisms of inflammation are poorly explored. Survivin (Birc5) is an anti-apoptotic protein which inhibits Type 1 inflammation; however, this molecule has not been investigated in OSA.

METHODS

Forty-five patients with OSA and 31 non-OSA control subjects were involved. Venous blood was collected for plasma survivin measurements before and after diagnostic overnight polysomnography. Plasma survivin levels were compared between the two groups and correlated to OSA severity and comorbidities.

RESULTS

Plasma survivin levels were lower in OSA in the evening (27.6 ± 89.9 vs. 108.3 ± 161.2 pg/ml, p < 0.01) and in the morning (17.4 ± 48.6 vs. 36.4 ± 69.2 pg/ml, p = 0.02) compared to the control group. This OSA-related decrease was also present when only the non-obese patients were analysed. Significant indirect relationships were observed between plasma survivin levels and measures of OSA severity such as the apnoea-hypopnoea index (r = - 0.45) or oxygen desaturation index (r = - 0.40, both p < 0.01); however, when adjusting to BMI, these became insignificant (p > 0.05). Low plasma survivin concentrations were associated with high BMI (r = - 0.35), high CRP (r = - 0.31), low HDL cholesterol (r = 0.24) and high triglyceride levels (r = - 0.24, all p < 0.05).

CONCLUSION

Plasma survivin levels are reduced in OSA, relate to disease severity, and are associated with high CRP levels. This suggests an impaired immunoregulation in this disorder which needs to be studied in further detail.

Lax eyelid syndrome (LES), obstructive sleep apnea (OSA), and ocular surface inflammation

PURPOSE

Lax eyelid syndrome (LES) is defined as the association of distensible "floppy" eyelids and chronic papillary conjunctivitis. LES is also found in patients with obstructive sleep apnea (OSA) who have systemic elevation of inflammatory markers, including matrix metalloproteinases (MMP). Locally elevated MMP levels have also been demonstrated co-localized with elastin loss in eyelids of patients with LES, accounting for their "floppiness." The purpose of this study was to investigate tear film MMP levels and determine their association with eyelid laxity and OSA. We also evaluated 3 previous grading systems to determine the severity of lid laxity and introduced a new "laxometer" device.

METHODS

Thirty-seven subjects underwent bilateral eyelid laxity assessments prior to polysomnography testing. OSA severity was graded using the apnea hypopnea index (AHI). The degree of eyelid laxity was determined using three published methods and a newly proposed "laxometer" method. Commercially available InflammaDry^® kits were used to determine the presence of MMP-9 in the tear film.

RESULTS

There was a significant elevation in tear MMP-9 levels in patients with LES compared to controls (p < .05). Of the 37 total patients enrolled in this study, 2 patients (5.4%) did not have sleep study results. Thirty-two of the remaining 35 patients (91.4%) were determined to have OSA (AHI > 5). In this sample, there was no meaningful association between OSA and MMP-9 (p = .12). Although there were positive associations between OSA severity, laxometer measurements, and previously established grading methods, none achieved statistical significance (all p > .05).

CONCLUSIONS

There was an elevation of MMP-9 in tears of patients with LES. Elevated tear MMP-9 was also not associated with OSA. Although there is some evidence to support the association of eyelid laxity and OSA, the most accurate and reliable method for grading eyelid laxity remains unclear.

The relationship between pulmonary hypertension and obstructive sleep apnea

PURPOSE OF REVIEW

Although obstructive sleep apnea (OSA)-associated pulmonary hypertension is not uncommon and carries a worse prognosis if left untreated, it is less well recognized by clinicians. This review provides information on prevalence, pathophysiology, clinical presentation, treatment, and prognosis of pulmonary hypertension in OSA.

RECENT FINDINGS

The prevalence of pulmonary hypertension in OSA ranges from 17 to 53%. The underlying pathophysiology is complex and yet to be fully understood. Continuous positive airway pressure has been proven to be efficacious in the treatment of OSA-associated pulmonary hypertension.

SUMMARY

There is still lack of research in this field. We look forward to more well designed studies to help us understand this disease entity better.

May inflammatory markers be used for monitoring the continuous positive airway pressure effect in patients with obstructive sleep apnea and arrhythmias?

INTRODUCTION

Obstructive sleep apnea syndrome (OSAS) is defined by recurrent episodes of significant reduction or absence of the oro-nasal airflow during sleep, in the presence of thorax and abdominal movements and snoring. The pathophysiological consequences of intermittent hypoxia determined by OSAS are represented by systemic inflammation, the release of free oxygen radicals and activation of the sympathetic nervous system. Cardiac arrhythmias are a frequent comorbidity in patients with OSAS.

HYPOTHESIS

We hypothesized that the continuous positive airway pressure (CPAP) therapy has an effect on inflammatory markers (erythrocyte sedimentation rate, fibrinogen, and red cell distribution width) in patients with OSAS and cardiac arrhythmias.

EVALUATION OF THE HYPOTHESIS

We tested this hypothesis on 52 patients diagnosed with OSAS and cardiac arrhythmias, divided into two groups: group A (patients who received CPAP therapy and pharmacological therapy) and group B (only pharmacological therapy). The patients were evaluated at enrollment (T0), at 3 and 6 months. We did not find a statistically significant difference of erythrocyte sedimentation rate (ESR) and fibrinogen levels between the two groups. Regarding the red cell distribution width (RDW), the CPAP treatment seems to have improved the RDW values in patients who received this treatment. Also, in patients from group A, a significant decrease in the average heart rate was noticed after 3 months.

CONSEQUENCES

Fibrinogen and ESR cannot be used for monitoring the CPAP therapy in patients with OSAS and arrhythmias. Instead, the beneficial effect of CPAP in patients with OSAS and cardiac arrhythmias can be monitored with the help of the RDW, which could also be used for evaluating the cardiovascular risk in patients with OSAS and arrhythmias.

Intermittent hypoxia-induced epiregulin expression by IL-6 production in human coronary artery smooth muscle cells

Patients with obstructive sleep apnea (OSA) experience repetitive episodes of desaturation and resaturation of blood oxygen (known as intermittent hypoxia or IH), during sleep. We showed previously that IH induced excessive proliferation of rat vascular smooth muscle cells through upregulation of members of the epidermal growth factor family, especially epiregulin (EREG), and the erbB2 receptor. In this study, we exposed human coronary artery smooth muscle cells to IH and found that IH significantly increased the expression of EREG. IH increased the production of interleukin‐6 (IL‐6) in smooth muscle cells, and the addition of IL‐6 induced EREG expression. Small interfering RNA for IL‐6 or IL‐6 receptor attenuated the IH‐induced increase in EREG. IL‐6 may play a pivotal role in EREG upregulation by IH and consequently OSA‐related atherosclerosis.

Contribution of TLR4 signaling in intermittent hypoxia-mediated atherosclerosis progression

Background

Intermittent hypoxia (IH), a typical character of obstructive sleep apnea (OSA), is related to atherogenesis. However, the role of IH on atherosclerosis (AS) progression and the mechanisms involved remains poorly understood.

Methods

In the present study, high-fat fed ApoE^−/− mice were treated with recombinant shRNA-TLR4 lentivirus and exposed to IH. Atherosclerotic lesions on the en face aorta and cross-sections of aortic root were examined by Oil-Red O staining. The content of lipids and collagen of aortic root plaques were detected by Oil-Red O staining and Sirius red staining, respectively. The TLR4, NF-κB p65, α-SMA and MOMA-2 expression in aorta and IL-6 and TNF-α expression in the mice serum were also detected.

Results

Compared with the Sham group, the IH treated group further increased atherosclerotic plaque loads and plaque vulnerability in the aortic sinus. Along with increased TLR4 expression, enhanced NF-κB activation, inflammatory activity and aggravated dyslipidemia were observed in the IH treated group. TLR4 interference partly inhibited IH-mediated AS progression with decreased inflammation and improved cholesterol levels. Similarly, in endothelial cells, hypoxia/reoxygenation exposure has been shown to promote TLR4 expression and activation of proinflammatory TLR4/NF-κB signaling, while TLR4 interference inhibited these effects.

Conclusions

We found that the IH accelerated growth and vulnerability of atherosclerotic plaque, which probably acted by triggering the activation of proinflammatory TLR4/NF-κB signaling. These findings may suggest that IH is a risk factor for vulnerable plaque and provide a new insight into the treatment of OSA-induced AS progression.

Elevations in neutrophils with obstructive sleep apnea: The Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

Obstructive sleep apnea (OSA) associates with increased risk of cardiovascular diseases (CVD). Immune abnormalities and surges in sympathetic activity accompany OSA and CVD. We hypothesized that OSA associates with leukocytosis partially by abnormalities in autonomic nervous system (ANS) function that would suggest a pathway linking OSA and CVD.

METHODS

Participants from the Multi-Ethnic Study of Atherosclerosis (MESA), a prospective cohort of individuals initially without overt CVD, underwent polysomnography and assays for white blood cells (WBC) and subsets. Heart rate (HR) and heart rate variability (HRV), indirect measurements of ANS, were obtained from overnight electrocardiography. A formal statistical mediation analysis tested the indirect effect that mean HR and HRV measures contribute to associations between OSA and leukocytosis.

RESULTS

The analytical sample consisted of 1298 participants (54% female), ages 54-93years, 14% with severe OSA (apnea-hypopnea-index, AHI≥30). Severe OSA associated with a higher prevalence of obesity, diabetes, and increased levels of WBC total and subsets. Neutrophil count associated with severe OSA after adjusting for confounders (p=0.017). Mean HR positively associated with OSA indices and neutrophils. A mediation analysis revealed an "indirect" effect of mean HR that explained an estimated 11% of the association between AHI and neutrophils. Overnight hypoxia also associated with neutrophil count (p=0.009), and mean HR explained 14% of the association between neutrophils and hypoxia.

CONCLUSIONS

In the MESA cohort, OSA measures associate with elevated neutrophil counts and increases in overnight mean HR. These data link innate immune dysregulation with OSA and provide a potential pathophysiologic pathway between CVD and OSA.

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.

Tumor necrosis factor alpha is a promising circulating biomarker for the development of obstructive sleep apnea syndrome: a meta-analysis

Obstructive sleep apnea syndrome (OSAS) is a chronic inflammatory disorder. The relationship between tumor necrosis factor alpha (TNF-alpha) and OSAS has been widely evaluated, but the results thus far remain inconclusive. We thereby decided to quantify the changes of TNF-alpha between OSAS patients and controls by a meta-analysis. This study complies with the MOOSE guidelines. Two reviewers independently searched articles and abstracted relevant data. In total, 47 articles (59 studies) were analyzed, including 2857 OSAS patients and 2115 controls. Overall, OSAS patients had a significantly higher level of circulating TNF-alpha than controls (weighted mean difference [WMD]: 9.66 pg/mL, 95% confidence interval [CI]: 8.66 to 11.24, P<0.001), but with significant heterogeneity (I²: 99.7%). After adjusting for potential missing studies, the overall estimate was weakened but still significant (filled WMD: 2.63 pg/mL, 95% CI: 2.56 to 2.70, P<0.001). When studies were stratified by OSAS severity, the changes in circulating TNF-alpha between patients and controls increased gradually with the more severe grades of OSAS. In patients with mild, mild-to-moderate, moderate, moderate-to-severe and severe OSAS, circulating TNF-alpha was higher than respective controls by 0.99, 1.48. 7.79, 10.08 and 8.85 pg/mL, with significant heterogeneity (I²: 91.2%, 74.5%, 97.6%, 99.0% and 98.1%). In conclusion, our findings demonstrated that circulating TNF-alpha was significantly higher in OSAS patients than in controls, and this difference became more pronounced with the more severe grades of OSAS, indicating that TNF-alpha might be a promising circulating biomarker for the development of OSAS.

Impairment of vascular strain in patients with obstructive sleep apnea

Background

Obstructive sleep apnea (OSA) is an independent risk factor for the development of cardiovascular diseases. Aim of this present study was to evaluate and extend recent research on the influence of obstructive sleep apnea on vascular strain.

Methods

A total number of 98 patients were integrated in the study. Patients were grouped according to the Apnea-Hypopnea-Index (AHI) in patients with mild-to-moderate OSA (5/h ≤ AHI < 30/h), severe OSA (AHI ≥ 30/h) and controls (AHI < 5/h). Groups were matched in age, body-mass-index and cardiovascular risks. Vascular strain of common carotid arteries was assessed by ultrasound speckle-tracking. A minor group of 30 patients and controls further underwent assessment of vascular strain of brachial and femoral arteries. Additionally, all patients underwent blood testing to reveal potential influences of inflammatory markers on arterial stiffness. In additional analysis we examined the effect of statin therapy on vascular strain.

Results

Patients with OSA showed significantly reduced values of vascular strain of common carotid arteries. Radial and circumferential strains were significantly lower in both patients with mild-to-moderate (p = .05) and patients with severe OSA (p = .001) compared to control. Vascular strain parameters of brachial and femoral arteries showed no consistent results. There were no significant correlations of inflammatory markers with vascular strain parameters. No significant differences in vascular strain were detected between statin and non-statin groups.

Conclusion

Patients with OSA show significantly reduced vascular strain assessed by ultrasound-based speckle-tracking. Vascular stiffness increases with the severity of the disease. Target vessels to assess vascular strain in patients with OSA are common carotid arteries, whereas other sites of the arterial tree are not reliable. No significant impact of current statin therapy on vascular strain was found. Further studies are needed to evaluate potential benefit of statins in secondary prevention of atherosclerosis in OSA.

The importance of calprotectin levels in obstructive sleep apnea syndrome severity

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is mostly seen in adult populations. It is known that increased levels of several inflammatory mediators play roles in OSAS and related comorbidities. Calprotectin is an inflammatory mediator that increases in some diseases such as Behçet's syndrome, bowel diseases and cardiovascular and cerebrovascular diseases.

AIMS

The purpose of this study was to investigate whether calprotectin can be used as a biomarker in OSAS by determining the relation between serum calprotectin levels and OSAS severity.

STUDY DESIGN

Cohort study.

METHODS

A prospective study was planned. Eighty-three patients undergoing polysomnography were included in the study and evaluated prospectively. Thirty patients were classified as non-OSAS (group 1), 18 as mild OSAS (group 2), 15 as moderate OSAS (group 3) and 20 as severe OSAS (group 4). Calprotectin values were measured in the non-OSAS patients (group 1) and in the patients with OSAS (groups 2, 3 and 4). The OSAS groups were also compared with each other.

RESULTS

Serum calprotectin values ranged between 70.61 and 1468.04 ng/ml. No significant difference in calprotectin levels was found between the OSAS and normal groups. However, statistically significantly increased calprotectin values were determined in the severe OSAS group (group 4) when all groups were compared.

CONCLUSION

Calprotectin values were elevated in OSAS patients and it can be used as a marker of severe OSAS. Future studies can support our study.

Determinants of sleepiness in obstructive sleep apnea

STUDY OBJECTIVES

Significant interindividual variability in sleepiness is observed in clinical populations with obstructive sleep apnea (OSA). This phenomenon is only partially explained by the apnea-hypopnea index (AHI). Understanding factors that lead to sleepiness is critical to effective management of patients with OSA. We examined demographic and other factors associated with sleepiness in OSA.

METHODS

Prospective study of 283 patients with newly diagnosed OSA by polysomnography (AHI ≥ 5 per hour). Subjective sleepiness (Epworth Sleep Scale [ESS] ≥ 11) and objective sleepiness (psychomotor vigilance task [PVT] mean lapse ≥ 2) were assessed.

RESULTS

Participants were classified into four groups (1: sleepy by ESS and PVT, 2: sleepy by PVT only, 3: sleepy by ESS only, and 4: nonsleepy reference group) and compared by generalized logit model. Shorter daily sleep duration by actigraphy and less morningness were associated with higher risk of sleepiness (Odds ratio [OR] = 0.52, 95% confidence interval [CI] 0.33-0.82 and OR = 0.89, CI 0.80-0.98, respectively). African-American race was associated with sleepiness (group 1, OR = 8.8, CI 2.8-27.3; group 2, OR = 16.6, CI 3.3-83.6; and group 3, OR = 3.3, CI 1.0-10.1). IL-6 level was higher in groups 1 and 3 (OR = 1.9, CI 1.0-3.4 and OR 2.0, CI 1.1-3.7, respectively).

CONCLUSIONS

African-American race, short sleep duration, chronotype, and increased proinflammatory cytokine IL-6 level were associated with sleepiness in OSA. These findings will inform future investigations determining mechanisms of sleepiness in OSA.

Neutrophil-to-lymphocyte ratio decreases in obstructive sleep apnea treated with mandibular advancement devices

PURPOSE

Obstructive sleep apnea has been associated with chronic inflammation triggered by nocturnal hypoxemia. The neutrophil-to-lymphocyte ratio (NLR) is a measure of subclinical systemic inflammation. We hypothesize that NLR levels would improve as chronic inflammation diminishes in obstructive sleep apnea (OSA) patients treated with mandibular advancement devices (MADs).

METHODS

We studied patients with OSA who were treated with MAD as a first-line treatment or because they could not tolerate CPAP. We obtained pre-treatment and post-treatment complete blood counts. NLR was calculated by dividing the number of neutrophils by the number of lymphocytes obtained from the CBCs. Patients with other conditions known to affect NLR were excluded from the study.

RESULTS

We compared the values of NLR and oxygen desaturation index (ODI) before and after treatment with MAD in 22 patients who met inclusion criteria and completed the study protocol. There was a significant difference in NLR before and after treatment (p = 0.01). There was also a significant difference in the 3% ODI and 4% ODI before and after treatment with MAD (p = 0.014, 0.007), respectively. A subgroup analysis compared NLR in two groups of patients, the optimally treated and suboptimally treated. There was a significant decrease in the NLR in the optimally treated group (n = 10) (p < 0.01), whereas it did not change in the suboptimally treated group (n = 12) (p = 0.349).

CONCLUSION

The neutrophil-to-lymphocyte ratio may be useful in documenting improvement in inflammation for OSA patients treated with mandibular advancement devices. Our results specifically suggest that the NLR values are associated with the decrease in the ODI.

Neuroendocrine and Inflammatory Responses to Losartan and Continuous Positive Airway Pressure in Patients with Hypertension and Obstructive Sleep Apnea. A Randomized Controlled Trial

RATIONALE

Blood pressure reduction in response to antihypertensive agents is less for patients with obstructive sleep apnea (OSA). Increased sympathetic and inflammatory activity, as well as alterations in the renin-angiotensin-aldosterone system, may play a role in this context.

OBJECTIVES

To address the cardiovascular mechanisms involved in response to an angiotensin II receptor antagonist, losartan, and continuous positive airway pressure (CPAP) as add-on treatment for hypertension and OSA.

METHODS

Newly diagnosed hypertensive patients with or without OSA (allocated in a 2:1 ratio for OSA vs. no OSA) were treated with losartan 50 mg daily during a 6-week two-center, open-label, prospective, case-control, parallel-design study. In the second 6-week, sex-stratified, open-label, randomized, parallel-design study, all subjects with OSA continued to receive losartan and were randomly assigned to either CPAP as add-on therapy or to no CPAP (1:1 ratio for CPAP vs. no CPAP). Study subjects without OSA were followed in parallel while they continued to take losartan. Blood samples were collected at baseline, after 6 weeks, and after 12 weeks for analysis of renin, aldosterone, noradrenaline, adrenaline, and inflammatory markers.

MEASUREMENTS AND MAIN RESULTS

Fifty-four patients with OSA and 35 without OSA were included in the first 6-week study. Losartan significantly increased renin levels and reduced aldosterone levels in the group without OSA. There was no significant decrease in aldosterone levels among patients with OSA. Add-on CPAP treatment tended to lower aldosterone levels, but reductions were more pronounced in measures of sympathetic activity. No significant changes in inflammatory markers were observed following treatment with losartan and CPAP.

CONCLUSIONS

Hypertensive patients with OSA responded to losartan treatment with smaller reductions in aldosterone compared with hypertensive patients without OSA. Sympathetic system activity seemed to respond primarily to add-on CPAP treatment in patients with newly discovered hypertension and OSA. Clinical trial registered with www.clinicaltrials.gov (NCT00701428).

Decrease of perforin positive CD3+γδ-T cells in patients with obstructive sleep disordered breathing

Introduction

Sleep related breathing disorders (SRBD) cause sleep fragmentation, intermittent hypoxia or a combination of both leading to homeostasis perturbations, including in the immune system. We investigated whether SRBD patients with or without intermittent hypoxia show substantial differences in perforin and granzyme-B positive peripheral blood lymphocytes.

Methods

A total of 87 subjects were included and distributed as follows: 24 controls (C), 19 patients with respiratory effort related arousals due to increased upper airway resistance (UAR) without hypoxic events, 24 obese patients with obstructive sleep apnea (OSA) (oOSA), and 20 without obesity (noOSA). After polysomnographic recording, we analyzed in fasting blood samples routine hematologic and biochemical parameters and the percentage of lymphocytes containing the proteins perforin and granzyme-B (GrB). Kruskal-Wallis tests and a posteriori multiple comparisons were applied for statistical analysis of results.

Results

Perforin-positive γδ-cells revealed significant differences between groups (p = 0.017), especially between the Control group and the oOSA (p-value = 0.04); the remaining SRBD groups also showed differences from the control (C vs UAR: p = 0.08; C vs noOSA = 0.09), but they did not raise to statistical significance. There were no differences among the SRBD groups. Granzyme-B cells were decreased in SRBD patients, but the differences were not statistically significant. No additional statistical significant result was found in the other investigated lymphocyte subsets.

Conclusions

Obstructive sleep-disordered breathing is associated with a decrease in perforin-positive CD3⁺γδ-T cells. Although this finding was detected in lean patients without intermittent hypoxia, the reduction was only statistically significant in obese patients with severe OSA. Because CD3⁺γδ-T cells play an important role in the control of tumor cells, our findings are directly relevant for the study of the association of OSA and cancer.

Electronic supplementary material

The online version of this article (10.1007/s11325-017-1602-6) contains supplementary material, which is available to authorized users.

Prevalence and risk factors of moderate to severe obstructive sleep apnea syndrome in major depression: a observational and retrospective study on 703 subjects

Background

Several studies have investigated the prevalence and risk factors of depression in subjects with obstructive sleep apnea syndrome. However, few studies have investigated the prevalence and risk factors for obstructive sleep apnea syndrome in major depression. The aim of this study was to examine the prevalence and risk factors of moderate to severe obstructive sleep apnea syndrome in a large sample of individuals with major depression.

Methods

Data from 703 individuals with major depression recruited from the research database of the sleep laboratory of the Erasme Hospital were analysed. An apnea-hypopnea index of ≥15 events per hour was used as cut-off score for moderate to severe obstructive sleep apnea syndrome. Logistic regression analyses were conducted to examine clinical and demographic risk factors of moderate to severe obstructive sleep apnea syndrome in major depression.

Results

The prevalence of moderate to severe obstructive sleep apnea syndrome in major depression is 13.94%. Multivariate logistic regression analysis revealed that male gender, snoring, excessive daytime sleepiness, lower insomnia complaint, presence of metabolic syndrome, age ≥ 50 years, BMI >30 kg/m², ferritin >300 μg/L, CRP >7 mg/L and duration of sleep ≥8 h were significant risk factors of moderate to severe obstructive sleep apnea syndrome in major depression.

Conclusion

Moderate to severe obstructive sleep apnea syndrome is a common pathology in major depression. The identification of these different risk factors advances a new perspective for more effective screening of moderate to severe obstructive sleep apnea syndrome in major depression.

A Randomized Crossover Trial Evaluating Continuous Positive Airway Pressure Versus Mandibular Advancement Device on Health Outcomes in Veterans With Posttraumatic Stress Disorder

STUDY OBJECTIVES

Despite the overall improvement in posttraumatic stress disorder (PTSD) symptomatology with continuous positive airway pressure (CPAP) therapy, adherence to CPAP is far worse in veterans with PTSD compared to the general population with obstructive sleep apnea (OSA). The aim of this study was to compare the efficacy, adherence, and preference of CPAP versus mandibular advancement device (MAD) and the effect of these treatments on health outcomes in veterans with PTSD.

METHODS

Forty-two subjects with PTSD and newly diagnosed OSA by polysomnography were treated in a randomized, crossover trial of 12 weeks with CPAP alternating with MAD separated by a 2-week washout period. The primary outcome was the difference in titration residual apnea-hypopnea index (AHI) between CPAP and MAD. Secondary outcome measures included PTSD Checklist and health-related quality of life (Medical Outcomes Study 36-Item Short Form and Pittsburgh Sleep Quality Index).

RESULTS

Analyses were limited to the 35 subjects (mean age 52.7 ± 11.6 years) who completed the trial, regardless of compliance with their assigned treatment. CPAP was more efficacious in reducing AHI and improving nocturnal oxygenation than MAD (P < .001 and P = .04, respectively). Both treatments reduced PTSD severity and ameliorated scores of the Medical Outcomes Study Short Form 36 and Pittsburgh Sleep Quality Index, although no differences were detected between the CPAP and MAD arms. The reported adherence to MAD was significantly higher than CPAP (P < .001), with 58% preferring MAD to CPAP.

CONCLUSIONS

Although CPAP is more efficacious than MAD at improving sleep apnea, both treatment modalities imparted comparable benefits for veterans with PTSD in relation to PTSD severity and health-related quality of life. MAD offers a viable alternative for veterans with OSA and PTSD who are nonadherent to CPAP.

CLINICAL TRIAL REGISTRATION

Title: A Randomized Cross Over Trial of Two Treatments for Sleep Apnea in Veterans With Post-Traumatic Stress Disorder; URL: https://www.clinicaltrials.gov/ct/show/NCT01569022; Identifier: NCT01569022.

Cardiovascular effects of oral appliance therapy in obstructive sleep apnea: A systematic review and meta-analysis

Obstructive sleep apnea (OSA) is associated with increased cardiovascular morbidity and mortality. This study systematically reviews the effects of oral appliance therapy (OAT) on a broad spectrum of cardiovascular outcomes. A literature search was performed up to December 31st 2016. Twenty-five relevant full-text articles were retrieved. Sixteen articles were considered methodologically sufficient, including 11 randomized controlled trials. Pooled data of the RCTs showed significant reductions in daytime systolic and diastolic blood pressure compared to baseline, but no significant reductions in heart rate, except for daytime heart rate when compared to inactive/placebo OAT. OAT and continuous positive airway pressure (CPAP) were equally effective in reducing blood pressure. Studies assessing the effect of OAT on heart rate variability, circulating cardiovascular biomarkers, and endothelial function and arterial stiffness, generally involved small numbers of patients, and were heterogeneous and inconclusive. Studies assessing the effect of OAT on cardiac function showed no effects on echocardiographic outcomes. One observational study showed that OAT was as effective as CPAP in reducing cardiovascular death. It could be speculated that OAT may lead to a reduction in long-term cardiovascular morbidity and mortality in OSA patients. However, further methodologically high quality, longitudinal studies are warranted to address this key question.

Peripapillary Choroidal Thickness and Retinal Nerve Fiber Layer in Untreated Patients with Obstructive Sleep Apnea-Hypopnea Syndrome: A Case-Control Study

PURPOSE

To evaluate peripapillary choroidal thickness (PPCT), central macular choroidal thickness (CMCT), and retinal nerve fiber layer (RNFL) thickness in untreated patients with obstructive sleep apnea-hypopnea syndrome (OSAHS).

METHODS

This prospective, randomized, and comparative study was conducted in a university ophthalmology clinic. 106 eyes of 106 patients with OSAHS and 44 eyes of 44 healthy individuals were evaluated in this study. Only right eyes were evaluated. The patients with OSAHS were divided into three groups as mild (group 1), moderate (group 2), and severe (group 3) according to apnea-hypopnea index. The PPCT, CMCT, and RNFL measurements were performed by using spectral domain optical coherence tomography with enhanced depth imaging technique. The main parameters assessed were PPCT-Temporal, PPCT-Superior, PPCT-Nasal, PPCT-Inferior quadrants, CMCT, and RNFL thicknesses.

RESULTS

The PPCT of all quadrants was significantly thicker in the control group compared with the moderate and severe subgroups of OSAHS (p < 0.05). The PPCT-Superior and PPCT-Temporal were significantly thinner in the mild subgroup compared with the control group (p = 0.003 and p = 0.028, respectively). There was no difference between the control and mild groups regarding the RNFL thicknesses except nasal RNFL and inferotemporal RNFL which are thinner in the mild group. The RNFL thicknesses of all quadrants were significantly thicker in the control group compared with moderate and severe subgroups (p < 0.05). The CMCT was significantly thicker in the control group compared with all subgroups of OSAHS (p < 0.05).

CONCLUSIONS

In OSAHS patients, PPCT, CMCT, and RNFL were significantly thinner compared with the control group. These results may explain why OSAHS patients are prone to normotensive glaucoma.

Correction of intermittent hypoxia reduces inflammation in obese subjects with obstructive sleep apnea

BACKGROUND

In obese subjects with obstructive sleep apnea (OSA), chronic intermittent hypoxia (CIH) may be linked to systemic and adipose tissue inflammation.

METHODS

We obtained abdominal subcutaneous adipose tissue biopsies from OSA and non-OSA obese (BMI > 35) subjects at baseline and after 24 weeks (T1) of weight-loss intervention plus continuous positive airway pressure (c-PAP) or weight-loss intervention alone, respectively. OSA subjects were grouped according to good (therapeutic) or poor (subtherapeutic) adherence to c-PAP.

RESULTS

At baseline, anthropometric and metabolic parameters, serum cytokines, and adipose tissue mRNA levels of obesity-associated chemokines and inflammatory markers were not different in OSA and non-OSA subjects. At T1, body weight was significantly reduced in all groups. Serum concentrations of IL-2, IL-4, IL-6, MCP-1, PDGFβ, and VEGFα were reduced by therapeutic c-PAP in OSA subjects and remained unaltered in non-OSA and subtherapeutic c-PAP groups. Similarly, adipose tissue mRNA levels of macrophage-specific (CD68, CD36) and ER stress (ATF4, CHOP, ERO-1) gene markers, as well as of IL-6, PDGFβ, and VEGFα, were decreased only in the therapeutic c-PAP group.

CONCLUSION

CIH does not represent an additional factor increasing systemic and adipose tissue inflammation in morbid obesity. However, in subjects with OSA, an effective c-PAP therapy improves systemic and obesity-associated inflammatory markers.

FUNDING

Ministero dell'Università e della Ricerca and Progetti di Rilevante Interesse Nazionale.

A Preliminary Investigation of the Association of Sleep With Inflammation and Oxidative Stress Biomarkers and Functional Outcomes After Stroke Rehabilitation

This study examined the association of sleep with inflammation and oxidative stress biomarkers, and with functional outcomes, after stroke rehabilitation. The rehabilitation effects on biomarkers and functional outcomes were also evaluated. Twenty subacute stroke survivors received 4 weeks of upper limb rehabilitation. Baseline inflammatory (i.e., soluble intercellular adhesion molecule-1, sICAM-1) and oxidative stress biomarkers (i.e., glutathione peroxidase, GPx and malondialdehyde, MDA) were assessed, as were sleep outcomes. Positive correlations were observed between baseline level of sICAM-1 and number of awakenings at post-treatment (ρ = 0.51, p < 0.05) as well as between baseline level of MDA and post-performance time of the Wolf Motor Function Test (WMFT-time) (ρ = 0.46, p < 0.05). In addition, MDA levels were significantly decreased, and functional outcomes of the modified Rankin Scale (mRS), functional ability scale of the WMFT, and Stroke Impact Scale (SIS-total, and SIS-physical function) were improved after the rehabilitation. This pilot study emphasizes the relationship among biomarkers, sleep, and functional outcomes after stroke rehabilitation. Oxidative stress markers may be useful predictors of functional outcomes in subacute stroke survivors.

Evaluation of Inflammatory Markers in a Large Sample of Obstructive Sleep Apnea Patients without Comorbidities

Systemic inflammation is important in obstructive sleep apnea (OSA) pathophysiology and its comorbidity. We aimed to assess the levels of inflammatory biomarkers in a large sample of OSA patients and to investigate any correlation between these biomarkers with clinical and polysomnographic (PSG) parameters. This was a cross-sectional study in which 2983 patients who had undergone a polysomnography for OSA diagnosis were recruited. Patients with known comorbidities were excluded. Included patients (n = 1053) were grouped according to apnea-hypopnea index (AHI) as mild, moderate, and severe. Patients with AHI < 5 served as controls. Demographics, PSG data, and levels of high-sensitivity C-reactive protein (hs-CRP), fibrinogen, erythrocyte sedimentation rate (ESR), and uric acid (UA) were measured and compared between groups. A significant difference was found between groups in hs-CRP, fibrinogen, and UA. All biomarkers were independently associated with OSA severity and gender (p < 0.05). Females had increased levels of hs-CRP, fibrinogen, and ESR (p < 0.001) compared to men. In contrast, UA levels were higher in men (p < 0.001). Our results suggest that inflammatory markers significantly increase in patients with OSA without known comorbidities and correlate with OSA severity. These findings may have important implications regarding OSA diagnosis, monitoring, treatment, and prognosis. This trial is registered with ClinicalTrials.gov number NCT03070769.

Obstructive Sleep Apnea and Hallmarks of Aging

Obstructive sleep apnea (OSA) is one of the most common sleep disorders. Since aging is a risk factor for OSA development, it is expected that its prevalence will increase with the current increase in life span. In recent years, several studies have shown that OSA potentially contributes to functional decline, mainly prompted by chronic intermittent hypoxia and sleep fragmentation. Here, we propose that OSA might anticipate/aggravate aging by inducing cellular and molecular impairments that characterize the aging process, such as stem cell exhaustion, telomere attrition and epigenetic changes. We suggest that further knowledge on the impact of OSA on aging mechanisms might contribute to a better understanding of how OSA might putatively accelerate aging and aging-related diseases.

Prevalence and risk factors of moderate to severe obstructive sleep apnea syndrome in insomnia sufferers: a study on 1311 subjects

Background

Several studies have investigated the prevalence and risk factors of insomnia in subjects with obstructive sleep apnea syndrome. However, few studies have investigated the prevalence and risk factors for obstructive sleep apnea syndrome in insomnia sufferers. Thus, the aim of this study was to examine the prevalence and risk factors of moderate to severe obstructive sleep apnea syndrome in a large sample of insomnia sufferers.

Methods

Data from 1311 insomnia sufferers who were recruited from the research database of the sleep laboratory of the Erasme Hospital were analysed. An apnea-hypopnea index of ≥15 events per hour was used as the cut-off score for moderate to severe obstructive sleep apnea syndrome. Logistic regression analyses were conducted to examine clinical and demographic risk factors of moderate to severe obstructive sleep apnea syndrome in insomnia sufferers.

Results

The prevalence of moderate to severe obstructive sleep apnea syndrome in our sample of insomnia sufferers was 13.88%. Multivariate logistic regression analysis revealed that male gender, snoring, excessive daytime sleepiness, lower maintenance insomnia complaint, presence of metabolic syndrome, age ≥ 50 & <65 years, age ≥ 65 years, BMI ≥ 25 & <30 kg/m², BMI >30 kg/m², and CRP >7 mg/L were significant risk factors of moderate to severe obstructive sleep apnea syndrome in insomnia sufferers.

Conclusion

Moderate to severe obstructive sleep apnea syndrome is a common pathology in insomnia sufferers. The identification of these different risk factors advances a new perspective for more effective screening of moderate to severe obstructive sleep apnea syndrome in insomnia sufferers.

Screening for obstructive sleep apnea syndrome in asthma patients: a prospective study based on Berlin and STOP-Bang questionnaires

BACKGROUND

The bidirectional relationship of asthma and obstructive sleep apnea (OSA) has been confirmed in recent years. However, in the clinical practice, majority of asthma patients did not pay adequate attention to their sleep apnea condition. Berlin questionnaire (BQ) and STOP-Bang questionnaire (SBQ) are two most common OSA screening questionnaires to screen high-risk patients for OSA. This study aimed at evaluating the predictive performance of BQ and SBQ for OSA in asthma patients.

METHODS

Asthma outpatients of Zhongshan Hospital were enrolled into the study. All patients were asked to fill in the BQ and SBQ and clinical characteristics and asthma characteristics were recorded. Univariate and multivariate logistic regression analyses were applied to identify risk factors of OSA in asthma patients. With the gold standard of laboratory-based overnight polysomnography (PSG), the predictive performance of SBQ and BQ was evaluated and compared. The probability of OSA severity was predicted by various SBQ scores in asthma patients.

RESULTS

A total of 123 asthma patients (average age 47.56±12.12 years; 57.72% males) were enrolled and underwent PSG diagnosis overnight at Sleep Center. Logistic regression analyses showed that rhinitis (adjusted OR =4.30; 95% CI: 1.50-12.37, P=0.007) and dyslipidemia (adjusted OR =2.75; 95% CI: 1.16-6.51, P=0.021) were associated with OSA in asthma patients after adjusting for known OSA risk factors. No asthma functional characteristic differences were found to be associated with OSA severity in the study. The prevalence of moderate-to-severe OSA (AHI ≥15) in the asthmatic population sample was 36.59% (45/123). Questionnaires predictive results showed that compared with BQ, SBQ has higher diagnostic sensitivity (84.4% vs. 60%), lower specificity (79.5% vs. 91%) lower positive predictive value (PPV): (70.4% vs. 79.4%) and higher negative predictive value (NPV) (90% vs. 80%) to detect moderate-to-severe OSA at the cut-off as AHI of 15/h. OSA probability results showed that with the increasing of the questionnaire scores, the moderate and severe OSA probability of SBQ rose significantly.

CONCLUSIONS

SBQ is a preferable sleep questionnaire better than BQ for detecting moderate and severe OSA in asthma patients which should be validated in larger population sample.

Obstructive sleep apnoea and related comorbidities in incident idiopathic pulmonary fibrosis

The objectives of this prospective study were: 1) to determine the prevalence and determinants of obstructive sleep apnoea (OSA) in patients with newly diagnosed idiopathic pulmonary fibrosis (IPF); 2) to determine whether OSA was associated with cardiovascular disease (CVD) as well as increased oxidative stress and levels of IPF biomarkers in the blood.

A group of 45 patients with newly diagnosed IPF attended polysomnography. The prevalence of CVD and the severity of coronary artery calcification were investigated by high-resolution computed tomography. The levels of 8-hydroxydeoxyguanosine (8-OH-DG) and various IPF biomarkers in the blood were compared between patients with no or mild OSA (apnoea–hypopnoea index (AHI) <15 events·h−1), with moderate OSA (15 ≤AHI <30 events·h−1) and with severe OSA (AHI ≥30 events·h−1).

The prevalence of moderate-to-severe OSA and severe OSA was 62% and 40%, respectively. AHI did not correlate with demographic or physiological data. All patients with severe OSA had a medical history of CVD,versus41.2% and 40% of those with no or mild OSA, or with moderate OSA, respectively (p<0.0001). Ischaemic heart disease (IHD) and moderate-to-severe coronary artery calcifications were strongly associated with severe OSA. The 8-OH-DG and matrix metalloproteinase-7 serum levels were significantly increased in the severe OSA group.

Moderate-to-severe OSA is highly prevalent in incident IPF and severe OSA is strongly associated with the presence of CVD, particularly IHD.

Sleep and CKD in Chinese Adults: A Cross-Sectional Study

BACKGROUND AND OBJECTIVES

To assess the association between self-reported sleep duration and quality and odds of having CKD in Chinese adults on the basis of a community study.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this cross-sectional study, we included 11,040 Chinese adults who participated in an ongoing prospective study, the Kailuan cohort. Survey questionnaire items addressed insomnia, daytime sleepiness, snoring, and sleep duration during their 2012 interview. Overall sleep quality was evaluated by summarizing these four sleep parameters. Fasting blood samples and single random midstream morning urine samples were collected in 2012 and analyzed for serum creatinine and proteinuria. CKD was defined by eGFR<60 ml/min per 1.73 m2 or proteinuria >300 mg/dl. We also examined those at high or very high risk of having CKD, on the basis of the Kidney Disease Improving Global Outcomes recommendations. The association between sleep quality and CKD was assessed using logistic regression model.

RESULTS

Worse overall sleep quality was associated with higher likelihood of being high or very high risk for CKD (multiadjusted odds ratio, 2.69; 95% confidence interval, 1.30 to 5.59 comparing two extreme categories; P trend <0.01), but not overall CKD (multiadjusted odds ratio, 1.58; 95% confidence interval, 0.89 to 2.80 comparing two extreme categories; P trend =0.46), after adjusting for potential confounders. Specifically, individuals with worse sleep quality were more likely to have proteinuria (multiadjusted odds ratio, 1.95; 95% confidence interval, 1.03 to 3.67 comparing two extreme categories; P trend =0.02), rather than lower eGFR level (multiadjusted mean eGFR levels were 96.4 and 93.6 ml/min per 1.73 m2 in the two extreme sleep categories, respectively; P trend =0.13). However, there was no statistically significant association between individual sleep parameters and CKD status.

CONCLUSIONS

Worse overall sleep quality was associated with higher odds of being high or very high risk for CKD and proteinuria in Chinese adults.