Serum leptin and vascular risk factors in obstructive sleep apnea

Clinical correlates of obstructive sleep apnoea in idiopathic normal pressure hydrocephalus

BACKGROUND AND PURPOSE

The pathogenesis of idiopathic normal pressure hydrocephalus (iNPH) remains controversial. Limited studies have indicated a high prevalence of obstructive sleep apnoea (OSA) amongst iNPH patients. The aim was to investigate the clinical correlates of OSA in iNPH patients.

METHODS

In this cross-sectional observational study, consecutive iNPH patients were prospectively enrolled. Evaluations included the iNPH Rating Scale, the Movement Disorder Society Unified Parkinson's Disease Rating Scale part III, the time and number of steps to walk 10 m, the Epworth Sleepiness Scale, the Pittsburgh Sleep Quality Index, a complete neuropsychological evaluation, 3-T brain MRI, full-night video-polysomnography, tap test and cerebrospinal fluid (CSF) neurodegeneration biomarkers.

RESULTS

Fifty-one patients were screened, of whom 38 met the inclusion criteria. Amongst the recruited patients, 19/38 (50%) exhibited OSA, with 12/19 (63.2%) presenting moderate to severe disorder. OSA+ iNPH patients required more time (p = 0.02) and more steps (p = 0.04) to complete the 10-m walking test, had lower scores on the gait subitem of the iNPH Rating Scale (p = 0.04) and demonstrated poorer performance on specific neuropsychological tests (Rey Auditory Verbal Learning Test immediate recall, p = 0.03, and Rey-Osterrieth Complex Figure, p = 0.01). Additionally, OSA+ iNPH patients had higher levels of total tau (p = 0.02) and phospho-tau (p = 0.03) in their CSF but no statistically significant differences in beta-amyloid (1-42) levels compared to OSA- iNPH patients.

CONCLUSION

Obstructive sleep apnoea is highly prevalent in iNPH patients, particularly at moderate to severe levels. OSA is associated with worse motor and cognitive performance in iNPH. The CSF neurodegeneration biomarker profile observed in OSA+ iNPH patients may reflect OSA-induced impairment of cerebral fluid dynamics.

Association of the risk of obstructive sleep apnoea with the severity of COVID-19

Patients with coronavirus 2019 (COVID-19) and obstructive sleep apnoea (OSA) have a worse prognosis than COVID-19 patients without OSA. This study aimed to examine the relationship between OSA risk and the severity of COVID-19 in patients undiagnosed with OSA. Patients diagnosed with COVID-19 and hospitalized or admitted to a community hotel were recruited for the study after recovery during a clinic check-up visit 6-8 weeks after discharge. At this visit, they answered the Epworth Sleeping Scale (ESS) and Berlin questionnaire. Demographic and clinical details were collected from electronic medical records. OSA risk was observed in 37 of 119 included patients (31.1%). Patients with high OSA risk were male, significantly older, had a higher body mass index (BMI), and had higher rates of hypertension and snoring than patients with low OSA risk. Moreover, OSA risk was associated with COVID-19 severity; 48.6% of patients with high risk for OSA suffered from severe COVID-19 compared to 22% of patients with low risk for OSA (p = 0.007). The duration of hospitalization for patients with a high OSA risk was 10.97±9.43 days, while that for those with a low OSA risk was 4.71±6.86 days (p = 0.001). After adjusting for BMI, age, hypertension, and chronic disease, the odds ratio was 4.3 (95%CI, 1.2-16, p = 0.029). A high OSA risk was associated with severe COVID-19 and longer hospitalization. Thus, we recommend that the Berlin and ESS questionnaires be completed for every COVID-19-infected patient at hospitalization, especially in the presence of comorbidities.

Assessment of Leptin Levels and Their Correlation With the Severity of Obstructive Sleep Apnea Syndrome: A Case-Control Study

Background Obstructive sleep apnea (OSA) is characterized by a combination of structural issues in the upper airway and imbalances in the respiratory control system. While numerous studies have linked OSA with obesity, it remains uncertain whether leptin, a hormone associated with fat, plays a role in the functional and anatomical defects that lead to OSA. Therefore, the aim of this study was to investigate whether leptin levels could be used as a predictor of OSA syndrome (OSAS). Methodology A case-control observational study was conducted, enrolling study participants who reported obesity (BMI > 30) within the range of >30 to <35 kg/m2, along with a short neck and a history of snoring, excessive daytime drowsiness, fatigue, or insomnia. Leptin levels and fasting blood sugar (FBS) were measured in all individuals. Additionally, the study evaluated the severity of OSAS using indicators such as the STOP BANG scores, apnea-hypopnea index, uvula grade score, and Epworth Sleepiness Scale scores. Results A total of 80 participants (40 cases and 40 controls) were included in the study. The mean leptin and FBS levels were significantly higher in cases compared to controls. Moreover, leptin levels exhibited a significant correlation with the severity indices of OSAS. Conclusion The study findings indicate that individuals with higher leptin levels tend to exhibit more severe OSAS symptoms. Furthermore, these elevated leptin levels contribute to the worsening of various OSA symptoms. Larger controlled studies have suggested that pharmacologically restoring the altered leptin levels may serve as a beneficial adjunct to treatment for alleviating OSAS symptoms.

Sleep and Inflammation

Sleep and inflammatory cytokines have a bidirectional relationship where circadian rhythms influence increase in levels of certain cytokines, and in return, some cytokines induce sleep, as we frequently experience during illnesses. The most commonly studied cytokines, in the context of inflammation and sleep, are interleukin 6 (IL-6), tumor necrosis factor (TNF), and (IL-1). In this article, the author follows the effect of circadian rhythms on blood levels of these cytokines and explores the changes in their levels in conditions that affect sleep, such as obstructive sleep apnea and insomnia.

Leptin and Asthma: What Are the Interactive Correlations?

Leptin is an adipokine directly correlated with the proinflammatory obese-associated phenotype. Leptin has been demonstrated to inhibit adipogenesis, promote fat demarcation, promote a chronic inflammatory state, increase insulin sensitivity, and promote angiogenesis. Leptin, a regulator of the immune response, is implicated in the pathology of asthma. Studies involved in the key cell reaction and animal models of asthma have provided vital insights into the proinflammatory role of leptin in asthma. Many studies described the immune cell and related cellular pathways activated by leptin, which are beneficial in asthma development and increasing exacerbations. Subsequent studies relating to animal models support the role of leptin in increasing inflammatory cell infiltration, airway hyperresponsiveness, and inflammatory responses. However, the conclusive effects of leptin in asthma are not well elaborated. In the present study, we explored the general functions and the clinical cohort study supporting the association between leptin and asthma. The main objective of our review is to address the knowns and unknowns of leptin on asthma. In this perspective, the arguments about the different faces of leptin in asthma are provided to picture the potential directions, thus yielding a better understanding of asthma development.

Higher Hospital Frailty Risk Score Is an Independent Predictor of In-Hospital Mortality in Hospitalized Older Adults with Obstructive Sleep Apnea

Background: Frailty predisposes individuals to stressors, increasing morbidity and mortality risk. Therefore, this study examined the impact of frailty defined by the Hospital Frailty Risk Score (HFRS) and other characteristics in older hospitalized patients with Obstructive Sleep Apnea (OSA). Methods: We conducted a retrospective study using the National Inpatient Sample 2016 in patients ≥65 years old with OSA. Logistic regression was used to evaluate the impact of frailty on inpatient mortality. A Kaplan-Meier curve with a log-rank test was used to estimate survival time between frailty groups. Results: 182,174 discharge records of elderly OSA were included in the study. 54% of the cohort were determined to be a medium/high frailty risk, according to HFRS. In multivariable analysis, frailty was associated with a fourfold (medium frailty, adjusted odd ratio (aOR): 4.12, 95% Confidence Interval (CI): 3.76−4.53, p-value < 0.001) and sixfold (high frailty, OR: 6.38, 95% CI: 5.60−7.27, p-value < 0.001) increased odds of mortality. Hospital survival time was significantly different between the three frailty groups (Log-rank test, p < 0.0001). Comorbidity burden defined by Charlson comorbidity Index (CCI) was associated with increased mortality (p < 0.001). Conclusion: More than half of the whole cohort was determined to be at medium and high frailty risk. Frailty was a significant predictor of in-hospital deaths in hospitalized OSA patients. Frailty assessment may be applicable for risk stratification of older hospitalized OSA patients.

Obstructive Sleep Apnoea and Lipid Metabolism: The Summary of Evidence and Future Perspectives in the Pathophysiology of OSA-Associated Dyslipidaemia

Obstructive sleep apnoea (OSA) is associated with cardiovascular and metabolic comorbidities, including hypertension, dyslipidaemia, insulin resistance and atherosclerosis. Strong evidence suggests that OSA is associated with an altered lipid profile including elevated levels of triglyceride-rich lipoproteins and decreased levels of high-density lipoprotein (HDL). Intermittent hypoxia; sleep fragmentation; and consequential surges in the sympathetic activity, enhanced oxidative stress and systemic inflammation are the postulated mechanisms leading to metabolic alterations in OSA. Although the exact mechanisms of OSA-associated dyslipidaemia have not been fully elucidated, three main points have been found to be impaired: activated lipolysis in the adipose tissue, decreased lipid clearance from the circulation and accelerated de novo lipid synthesis. This is further complicated by the oxidisation of atherogenic lipoproteins, adipose tissue dysfunction, hormonal changes, and the reduced function of HDL particles in OSA. In this comprehensive review, we summarise and critically evaluate the current evidence about the possible mechanisms involved in OSA-associated dyslipidaemia.

Caloric restriction prevents obesity- and intermittent hypoxia-induced cardiac remodeling in leptin-deficient ob/ob mice

Background: Intermittent hypoxia (IH), a key characteristic of obstructive sleep apnea, is independently associated with cardiometabolic impairment. While endogenous leptin levels may provide cardioprotective effects against hypoxia, leptin resistance is common among obese individuals presenting with obstructive sleep apnea.

Methods: Here, we assessed left ventricle (LV) function using M-mode echocardiography in lean wild-type, calorically-restricted ob/ob, and obese ob/ob mice before and after 6 days of IH to determine how obesity and intermittent hypoxia interact to affect cardiac function independent of leptin signaling.

Results: Calorically-restricting ob/ob mice for 4 weeks prior to IH exposure prevented weight gain (−2.1 ± 1.4 g) compared to free-fed ob/ob mice (8.7 ± 1.1 g). Free-fed ob/ob mice exhibited increased LV mass (0.713 ± 0.008 g) relative to wild-type mice (0.685 ± 0.004 g) and increased posterior wall thickness (0.089 ± 0.006 cm) relative to calorically-restricted ob/ob mice (0.072 ± 0.004 cm). Following 6 days of IH, free-fed ob/ob mice exhibited increases in cardiac output (44.81 ± 2.97 pre-IH vs. 57.14 ± 3.09 ml/min post-IH), LV diameter (0.400 ± 0.007 pre-IH vs. 0.428 ± 0.009 cm post-IH) and end diastolic volume (0.160 ± 0.007 pre-IH vs. 0.195 ± 0.012 ml post-IH) that were not detected in wild-type or calorically-restricted ob/ob mice.

Conclusion: Caloric restriction can prevent obesity-induced LV hypertrophy and protect against acute IH-induced cardiac remodeling independent of leptin signaling. These findings may have clinical implications for obstructive sleep apnea.

Gender Differences in the Context of Obstructive Sleep Apnea and Metabolic Diseases

The relationship between obstructive sleep apnea (OSA) and endocrine and metabolic disease is unequivocal. OSA, which is characterized by intermittent hypoxia and sleep fragmentation, leads to and exacerbates obesity, metabolic syndrome, and type 2 diabetes (T2D) as well as endocrine disturbances, such as hypothyroidism and Cushing syndrome, among others. However, this relationship is bidirectional with endocrine and metabolic diseases being considered major risk factors for the development of OSA. For example, polycystic ovary syndrome (PCOS), one of the most common endocrine disorders in women of reproductive age, is significantly associated with OSA in adult patients. Several factors have been postulated to contribute to or be critical in the genesis of dysmetabolic states in OSA including the increase in sympathetic activation, the deregulation of the hypothalamus-pituitary axis, the generation of reactive oxygen species (ROS), insulin resistance, alteration in adipokines levels, and inflammation of the adipose tissue. However, probably the alterations in the hypothalamus-pituitary axis and the altered secretion of hormones from the peripheral endocrine glands could play a major role in the gender differences in the link between OSA-dysmetabolism. In fact, normal sleep is also different between men and women due to the physiologic differences between genders, with sex hormones such as progesterone, androgens, and estrogens, being also connected with breathing pathologies. Moreover, it is very well known that OSA is more prevalent among men than women, however the prevalence in women increases after menopause. At the same time, the step-rise in obesity and its comorbidities goes along with mounting evidence of clinically important sex and gender differences. Metabolic and cardiovascular diseases, seen as a men's illness for decades, presently are more common in women than in men and obesity has a higher association with insulin-resistance-related risk factors in women than in men. In this way, in the present manuscript, we will review the major findings on the overall mechanisms that connect OSA and dysmetabolism giving special attention to the specific regulation of this relationship in each gender. We will also detail the gender-specific effects of hormone replacement therapies on metabolic control and sleep apnea.

Leptin Receptor Blockade Attenuates Hypertension, but Does Not Affect Ventilatory Response to Hypoxia in a Model of Polygenic Obesity

Background

Obesity can cause hypertension and exacerbates sleep-disordered breathing (SDB). Leptin is an adipocyte-produced hormone, which increases metabolic rate, suppresses appetite, modulates control of breathing, and increases blood pressure. Obese individuals with high circulating levels of leptin are resistant to metabolic and respiratory effects of leptin, but they appear to be sensitive to hypertensive effects of this hormone. Obesity-induced hypertension has been associated with hyperleptinemia. New Zealand obese (NZO) mice, a model of polygenic obesity, have high levels of circulating leptin and hypertension, and are prone to develop SDB, similarly to human obesity. We hypothesize that systemic leptin receptor blocker Allo-aca will treat hypertension in NZO mice without any effect on body weight, food intake, or breathing.

Methods

Male NZO mice, 12–13 weeks of age, were treated with Allo-aca (n = 6) or a control peptide Gly11 (n = 12) for 8 consecutive days. Doses of 0.2 mg/kg were administered subcutaneously 2×/day, at 10 AM and 6 PM. Blood pressure was measured by telemetry for 48 h before and during peptide infusion. Ventilation was assessed by whole-body barometric plethysmography, control of breathing was examined by assessing the hypoxic ventilatory response (HVR), and polysomnography was performed during light-phase at baseline and during treatment. Heart rate variability analyses were performed to estimate the cardiac autonomic balance.

Results

Systemic leptin receptor blockade with Allo-aca did not affect body weight, body temperature, and food intake in NZO mice. Plasma levels of leptin did not change after the treatment with either Allo-aca or the control peptide Gy11. NZO mice were hypertensive at baseline and leptin receptor blocker Allo-aca significantly reduced the mean arterial pressure from 134.9 ± 3.1 to 124.9 ± 5.7 mmHg during the light phase (P < 0.05), whereas the control peptide had no effect. Leptin receptor blockade did not change the heart rate or cardiac autonomic balance. Allo-aca did not affect minute ventilation under normoxic or hypoxic conditions and HVR. Ventilation, apnea index, and oxygen desaturation during NREM and REM sleep did not change with leptin receptor blockade.

Conclusion

Systemic leptin receptor blockade attenuates hypertension in NZO mice, but does not exacerbate obesity and SDB. Thus, leptin receptor blockade represents a potential pharmacotherapy for obesity-associated hypertension.

Metabolic dysfunction in OSA: Is there something new under the sun?

The growing number of patients with obstructive sleep apnea is challenging healthcare systems worldwide. Obstructive sleep apnea is characterized by chronic intermittent hypoxaemia, episodes of apnea and hypopnea, and fragmented sleep. Cardiovascular and metabolic diseases are common in obstructive sleep apnea, also in lean patients. Further, comorbidity burden is not unambiguously linked to the severity of obstructive sleep apnea. There is a growing body of evidence revealing diverse functions beyond the conventional tasks of different organs such as carotid body and gut microbiota. Chronic intermittent hypoxia and sleep loss due to sleep fragmentation are associated with insulin resistance. Indeed, carotid body is a multi-sensor organ not sensoring only hypoxia and hypercapnia but also acting as a metabolic sensor. The emerging evidence shows that obstructive sleep apnea and particularly chronic intermittent hypoxia is associated with non-alcoholic fatty liver disease. Gut dysbiosis seems to be an important factor in the pathophysiology of obstructive sleep apnea and its consequences. The impact of sleep fragmentation and intermittent hypoxia on the development of metabolic syndrome may be mediated via altered gut microbiota. Circadian misalignment seems to have an impact on the cardiometabolic risk in obstructive sleep apnea. Dysfunction of cerebral metabolism is also related to hypoxia and sleep fragmentation. Therefore, obstructive sleep apnea may alter cerebral metabolism and predispose to neurocognitive impairment. Moreover, recent data show that obstructive sleep apnea independently predicts impaired lipid levels. This mini-review will provide novel insights into the mechanisms of metabolic dysfunction in obstructive sleep apnea combining recent evidence from basic, translational and clinical research, and discuss the impact of positive airway pressure treatment on metabolic disorders.

Leptin receptor expression in the dorsomedial hypothalamus stimulates breathing during NREM sleep in db/db mice

STUDY OBJECTIVES

Obesity leads to obstructive sleep apnea (OSA), which is recurrent upper airway obstruction during sleep, and obesity hypoventilation syndrome (OHS), hypoventilation during sleep resulting in daytime hypercapnia. Impaired leptin signaling in the brain was implicated in both conditions, but mechanisms are unknown. We have previously shown that leptin stimulates breathing and treats OSA and OHS in leptin-deficient ob/ob mice and leptin-resistant diet-induced obese mice and that leptin's respiratory effects may occur in the dorsomedial hypothalamus (DMH). We hypothesized that leptin receptor LepRb-deficient db/db mice have obesity hypoventilation and that restoration of leptin signaling in the DMH will increase ventilation during sleep in these animals.

METHODS

We measured arterial blood gas in unanesthetized awake db/db mice. We subsequently infected these animals with Ad-LepRb or control Ad-mCherry virus into the DMH and measured ventilation during sleep as well as CO2 production after intracerebroventricular (ICV) infusions of phosphate-buffered saline or leptin.

RESULTS

Awake db/db mice had elevated CO2 levels in the arterial blood. Ad-LepRb infection resulted in LepRb expression in the DMH neurons in a similar fashion to wildtype mice. In LepRb-DMH db/db mice, ICV leptin shortened REM sleep and increased inspiratory flow, tidal volume, and minute ventilation during NREM sleep without any effect on the quality of NREM sleep or CO2 production. Leptin had no effect on upper airway obstruction in these animals.

CONCLUSION

Leptin stimulates breathing and treats obesity hypoventilation acting on LepRb-positive neurons in the DMH.

Obstructive sleep apnoea/hypopnoea syndrome: relationship with obesity and management in obese patients

Obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is a disease characterised by upper airway obstruction during sleep, quite frequent in the general population, even if underestimated. Snoring, sleep apnoea and diurnal hypersomnia are common in these patients. Central obesity plays a key role: it reduces the size and changes the conformation of the upper airways, besides preventing lung expansion, with consequent reduction of lung volumes. Furthermore, obese people are also resistant to leptin, which physiologically stimulates ventilation; as a result, this causes scarce awakening during apnoea. OSAHS diagnosis is based on the combination of clinical parameters, such as apnoea/hypopnoea index (AHI), medical history, physical examination and Mallampati score. The first objective reference method to identify OSAHS is polysomnography followed by sleep endoscopy. Therapy provides in the first instance reduction of body weight, followed by continuous positive airway pressure (CPAP), which still remains the treatment of choice in most patients, mandibular advancement devices (MAD) and finally otolaryngology or maxillofacial surgery. Among surgical techniques, central is barbed reposition pharyngoplasty (BRP), used in the field of multilevel surgery.

Time-dependence and comparison of regional and overall anthropometric features between Asian and Caucasian populations with obstructive sleep apnea: a cumulative meta-analysis

Background

Anthropometric measurements are simple and reachable tools for self-evaluating and screening patients with a high risk of obstructive sleep apnea (OSA). However, the accumulated relationship of obesity on the anthropometric characteristics of OSA is not well understood. The aim of the study was to show the time-dependent trend of OSA patients and compare overall and regional anthropometric between two ethnicities.

Methods

A cumulative meta-analysis was performed to assess obesity metrics in patients with and without OSA between Asians and Caucasians. We searched PubMed, Web of Science, Embase, and Scopus up to Jun 2020. Included studies used body mass index (BMI), neck circumference (NC), waist circumference (WC) and waist-to-hip ratio (WHR) as measures of anthropometric features in the adult OSA population and controls, utilized in-lab polysomnography or home sleep testing with apnea-hypopnea index (AHI) or respiratory disturbance index (RDI) classification, reported ethnicity/race, and were published in English. Any studies lacking one of these criteria or sufficient data were excluded.

Results

Forty studies with a total of 19,142 subjects were investigated. Comparison of changes between patients with and without OSA showed that OSA patients had a higher BMI [mean difference (MD) 3.12, 95% confidence interval (CI): 2.51–3.73], NC (MD 3.10, 95% CI: 2.70–3.51), WC (MD 9.84, 95% CI: 8.42–11.26) and waist-hip ratio (MD 0.04, 95% CI: 0.03–0.05) than the control subjects. The accumulated time-dependent increase in population with OSA was significantly apparent with all anthropometric features. BMI increased from 2000 (MD 0.50) to 2012 (MD 3.08–3.48) and remained stable afterwards (MD 2.70–3.17), NC increased from 2000 (MD 0.40) to 2013 (MD 3.09) and remained stable afterwards too (MD 3.06–3.21). WC increased from 2000 (MD 2.00) to 2012 (MD 9.37–10.03) and also remained stable afterwards (MD 8.99–9.84). WHR was stable from 2000 to 2004 with an MD of 0.01 and then stable from 2007 onwards with an increased MD of 0.03–0.04. Compared with Caucasian patients, Asian patients had lower obesity relevant variates.

Conclusions

BMI, NC, WC and WHR are associated with OSA in both ethnic groups. Anthropometry for overall and regional obesity could facilitate differentiation of patients with OSA from individuals without OSA by ethnicity.

The Association Between Serum/Plasma Leptin Levels and Obstructive Sleep Apnea Syndrome: A Meta-Analysis and Meta-Regression

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is associated with various adipokines. Leptin, a common adipokine, has attracted considerable attention of many researchers in recent years. So far, there has been little agreement on whether blood leptin levels differ in patients with OSAS. Thus, this meta-analysis examined the relationship between serum/plasma leptin levels and the occurrence of OSAS.

METHOD

WanFang, Embase, CNKI, Medline, SinoMed, Web of Science, and PubMed were searched for articles before March 30, 2021, with no language limitations. STATA version 11.0 and R software version 3.6.1 were used to analyze the obtained data. The weighted mean difference and correlation coefficients were used as the main effect sizes with a random-effects model and a fixed-effects model, respectively. Trial sequential analysis was conducted using dedicated software.

RESULT

Screening of 34 publications identified 45 studies that met the inclusion criteria of this meta-analysis and meta-regression. Our results suggested that plasma/serum leptin levels were remarkably higher in individuals with OSAS than in healthy individuals. Subgroup analyses were performed based on OSAS severity, ethnicity, age, body mass index, assay type, and sample source. The serum and plasma leptin levels were increased in nearly all OSAS subgroups compared to those in the corresponding control groups. Meta-regression analysis indicated that age, BMI, severity, assay approaches, study design, PSG type and ethnicity did not have independent effect on leptin levels. Furthermore, a positive relationship between the serum/plasma leptin level and apnea-hypopnea index (AHI) was found in the meta-analysis. The results of the trial sequential analysis suggested that the enrolled studies surpassed the required information size, confirming that our study findings were reliable.

CONCLUSION

Our study results demonstrate that OSAS patients have higher leptin levels in serum/plasma compared to controls, and the serum/plasma leptin level is positively correlated with AHI, especially in adults.

The relationship between NLRP3 rs10159239 and Vaspin rs2236242 gene variants and obstructive sleep apnea

BACKGROUND

In obstructive sleep apnea (OSA), recurrent upper airway obstruction and apnea/hypopnea episodes result in endothelial dysfunction, which leads to the release of many proinflammatory cytokines and reactive oxygen species (ROS). ROS induces NLRP3, a protein involved in the synthesis of interleukin (IL)-1 and IL-18; vaspin is a serine protease inhibitor that has an important role in suppressing the activation of NLRP3 inflammasome. In this study, we aimed to investigate the effect of NLRP3 rs10159239 (rs9239) and vaspin rs2236242 (rs6242) single nucleotide polymorphisms (SNPs) on OSA development.

METHODS

This study included 220 individuals who underwent polysomnography (118 patients with OSA and 102 healthy controls). NLRP3 rs9239 and vaspin rs6242 mutation frequencies were analyzed.

RESULTS

The NLRP3 rs9239 SNP genotype analysis revealed no statistically significant differences between the OSA and control groups. In the vaspin gene analysis, the rs6242 AA genotype was significantly more frequent in the OSA group compared with the control group, while the AT genotype was more frequent in controls (P = 0.004, P = 0.02). Comparison of rs6242 allele levels showed that the A allele was significantly more frequent in OSA patients than in controls (P = 0.03). The AA genotype was significantly more frequent in patients with severe OSA than in patients with mild or moderate OSA and the control group (P = 0.001 for all). Serum vaspin levels were significantly lower in carriers of the AA genotype than those with AT and TT genotypes (P = 0.001).

CONCLUSION

The vaspin rs6242 SNP AA genotype increased susceptibility to OSA, while the AT genotype appeared to be protective. The lower plasma vaspin levels in OSA compared with the control group and in patients with the AA genotype suggest that vaspin may be a protective biomarker for OSA.

Intranasal Leptin Prevents Opioid-induced Sleep-disordered Breathing in Obese Mice

Respiratory depression is the main cause of morbidity and mortality associated with opioids. Obesity increases opioid-related mortality, which is mostly related to comorbid obstructive sleep apnea. Naloxone, a μ-opioid receptor blocker, is an effective antidote, but it reverses analgesia. Like humans with obesity, mice with diet-induced obesity hypoventilate during sleep and develop obstructive sleep apnea, which can be treated with intranasal leptin. We hypothesized that intranasal leptin reverses opioid-induced sleep-disordered breathing in obese mice without decreasing analgesia. To test this hypothesis, mice with diet-induced obesity were treated with morphine at 10 mg/kg subcutaneously and with leptin or placebo intranasally. Sleep and breathing were recorded by barometric plethysmography, and pain sensitivity was measured by the tail-flick test. Excitatory postsynaptic currents were recorded in vitro from hypoglossal motor neurons after the application of the μ-opioid receptor agonist [D-Ala², N-MePhe⁴, Gly-ol]-enkephalin and leptin. Morphine dramatically increased the frequency of apneas and greatly increased the severity of hypoventilation and obstructive sleep apnea. Leptin decreased the frequency of apneas, improved obstructive sleep apnea, and completely reversed hypoventilation, whereas morphine analgesia was enhanced. Our in vitro studies demonstrated that [D-Ala², N-MePhe⁴, Gly-ol]-enkephalin reduced the frequency of excitatory postsynaptic currents in hypoglossal motoneurons and that application of leptin restored excitatory synaptic neurotransmission. Our findings suggest that intranasal leptin may prevent opioid respiratory depression during sleep in patients with obesity receiving opioids without reducing analgesia.

Effects of Obstructive Sleep Apnea and Obesity on Morphine Pharmacokinetics in Children

BACKGROUND

Obesity increases susceptibility to chronic pain, increases metabolism, and is associated with obstructive sleep apnea syndrome (OSAS), all which can complicate perioperative pain management of patients. In addition, obesity and OSAS can cause elevation of the adipose-derived hormone leptin, which increases metabolism. We hypothesized that obesity along with sleep apnea and leptin independently enhance morphine pharmacokinetics.

METHODS

Children 5-12 years of age who were presenting for surgery were administered a morphine dose of 0.05 mg/kg. Blood was collected at baseline and at subsequent preset times for pharmacokinetic analysis of morphine and its metabolites. Three groups were studied: a nonobese group with severe OSAS, an obese group with severe OSAS, and a control group.

RESULTS

Thirty-four patients consisting of controls (n = 16), nonobese/OSAS (n = 8), and obese/OSAS (n = 10) underwent analysis. The obese/OSAS group had a higher dose-adjusted mean maximum morphine concentration (CMAX) over 540 minutes compared to the controls (P < .001) and those with only OSAS (P = .014). The obese/OSAS group also had lower volume of distribution (Vd) when compared to OSAS-only patients (P = .007). In addition, those in the obese/OSAS group had a higher morphine 3-glucuronide (M3G) maximum concentration (P = .012) and a higher ratio of M3G to morphine than did the control group (P = .011). Time to maximum morphine 6-glucuronide (M6G) concentration was significantly lower in both nonobese/OSAS and obese/OSAS groups than in the control group (P < .005). C-reactive protein (CRP), interleukin (IL)-10, and leptin were all higher in the obese/OSAS group than in controls (P = .004, 0.026, and <0.001, respectively), and compared to OSAS-only patients, CRP (P = .013) and leptin (P = .002) levels were higher in the obese/OSAS group.

CONCLUSIONS

The combination of obesity and OSAS was associated with an increase in morphine metabolism compared with that in normal-weight controls. Our previous study in mice demonstrated that obesity from leptin deficiency decreased morphine metabolism, but that metabolism normalized after leptin replacement. Leptin may be a cause of the increased morphine metabolism observed in obese patients.

Metabolic syndrome and obstructive sleep apnea syndrome among patients with epilepsy on monotherapy

OBJECTIVES

The study aimed to determine the frequency of metabolic syndrome (MetS) and obstructive sleep apnea syndrome (OSAS) in patients with epilepsy receiving monotherapy and the relationship between these syndromes and antiepileptic drugs (AEDs).

METHODS

Two hundred and ninety-seven patients with epilepsy between the ages of 18-65 years receiving monotherapy for at least one year and 50 healthy participants were enrolled. Body mass indices and waist circumferences were measured. Serum fasting glucose levels, high-density lipoprotein (HDL), low density lipoprotein (LDL), total cholesterol (TC), triglyceride, and serum AED concentrations were noted. The frequency of MetS in patients with epilepsy was calculated. The snoring, tiredness, observed apnea, high blood pressure, body mass index, age, neck circumference, and male gender (STOP-Bang) questionnaire was used to determine the risk of OSAS. The relationship between these two syndromes and seizure type, disease duration, AED dosage, and treatment duration was analyzed.

RESULTS

Metabolic syndrome was more frequent in patients with epilepsy compared with healthy participants (32.6% vs. 12.0%), and it was diagnosed in 37.8% of patients receiving valproic acid (VPA), 36.1% of patients receiving carbamazepine (CBZ), 34.9% of patients receiving oxcarbazepine (OXC), and 30.5% of patients on levetiracetam (LEV). There was a positive correlation between VPA treatment duration and MetS existence (p < 0.05). However, MetS frequency did not change because of seizure type, disease duration, or AED dosages in patients with epilepsy receiving monotherapy. The risk for OSAS was higher in patients with epilepsy compared with healthy participants (24.6% vs. 12%), and it was calculated high in 27.7% of patients receiving CBZ, 32.2% of patients receiving LEV, and 30.2% of patients receiving OXC. The OSAS risk was higher in patients who have focal seizures than generalized seizures (p = 0.044). There was no relationship between OSAS risk and duration of epilepsy, duration of treatment, drug doses, and serum drug levels (p > 0.05).

CONCLUSION

Higher frequency of MetS and OSAS risk should be kept in mind on clinical follow-up of patients with epilepsy receiving monotherapy.

Evaluation of preoperative and postoperative serum interleukin-6, interleukin-8, tumor necrosis factor α and raftlin levels in patients with obstructive sleep apnea

BACKGROUND

Raftlin is a large, major lipid raft protein of cell membranes. Raftlin levels have not been previously examined in patients with obstructive sleep apnea (OSA). Our study aimed to evaluate the changes in raftlin, interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor alpha (TNFα) values from the preoperative state to the third month postoperatively in patients undergoing expansion sphincter pharyngoplasty for OSA.

METHODS

Of 60 patients, 10 patients had mild OSA (AHI 5-14), 10 moderate (AHI 15-29), 10 severe (AHI ≥ 30), and 30 with AHI < 5 formed a control group. Preoperatively and at 3 months post-operatively, IL-6, IL-8, TNFα, and raftlin values were measured.

RESULTS

Preoperatively, mean raftlin levels were 914.4 ± 62.7 pg/mL for controls, 910.0 ± 42.5 pg/mL in mild, 1000.5 ± 63.3 pg/mL in moderate, and 1386.3 ± 101.4 pg/mL in severe groups, with moderate and severe groups significantly elevated compared to controls (p < 0.001). Preoperatively to 3 months post-operatively, raftlin levels decreased significantly in each OSA group (p < 0.05). Levels of IL-6, IL-8 and TNFα followed similar patterns at baseline and after surgical intervention.

CONCLUSIONS

Raftlin levels at the third postoperative month decreased significantly compared with preoperative levels in parallel with other markers of inflammation.

Exploring the Mediators that Promote Carotid Body Dysfunction in Type 2 Diabetes and Obesity Related Syndromes

Carotid bodies (CBs) are peripheral chemoreceptors that sense changes in blood O₂, CO₂, and pH levels. Apart from ventilatory control, these organs are deeply involved in the homeostatic regulation of carbohydrates and lipid metabolism and inflammation. It has been described that CB dysfunction is involved in the genesis of metabolic diseases and that CB overactivation is present in animal models of metabolic disease and in prediabetes patients. Additionally, resection of the CB-sensitive nerve, the carotid sinus nerve (CSN), or CB ablation in animals prevents and reverses diet-induced insulin resistance and glucose intolerance as well as sympathoadrenal overactivity, meaning that the beneficial effects of decreasing CB activity on glucose homeostasis are modulated by target-related efferent sympathetic nerves, through a reflex initiated in the CBs. In agreement with our pre-clinical data, hyperbaric oxygen therapy, which reduces CB activity, improves glucose homeostasis in type 2 diabetes patients. Insulin, leptin, and pro-inflammatory cytokines activate the CB. In this manuscript, we review in a concise manner the putative pathways linking CB chemoreceptor deregulation with the pathogenesis of metabolic diseases and discuss and present new data that highlight the roles of hyperinsulinemia, hyperleptinemia, and chronic inflammation as major factors contributing to CB dysfunction in metabolic disorders.

Carotid Body and Metabolic Syndrome: Mechanisms and Potential Therapeutic Targets

The carotid body (CB) is responsible for the peripheral chemoreflex by sensing blood gases and pH. The CB also appears to act as a peripheral sensor of metabolites and hormones, regulating the metabolism. CB malfunction induces aberrant chemosensory responses that culminate in the tonic overactivation of the sympathetic nervous system. The sympatho-excitation evoked by CB may contribute to the pathogenesis of metabolic syndrome, inducing systemic hypertension, insulin resistance and sleep-disordered breathing. Several molecular pathways are involved in the modulation of CB activity, and their pharmacological manipulation may lead to overall benefits for cardiometabolic diseases. In this review, we will discuss the role of the CB in the regulation of metabolism and in the pathogenesis of the metabolic dysfunction induced by CB overactivity. We will also explore the potential pharmacological targets in the CB for the treatment of metabolic syndrome.

Leptin: Master Regulator of Biological Functions that Affects Breathing

Obesity is a global epidemic in developed countries accounting for many of the metabolic and cardiorespiratory morbidities that occur in adults. These morbidities include type 2 diabetes, sleep-disordered breathing (SDB), obstructive sleep apnea, chronic intermittent hypoxia, and hypertension. Leptin, produced by adipocytes, is a master regulator of metabolism and of many other biological functions including central and peripheral circuits that control breathing. By binding to receptors on cells and neurons in the brainstem, hypothalamus, and carotid body, leptin links energy and metabolism to breathing. In this comprehensive article, we review the central and peripheral locations of leptin's actions that affect cardiorespiratory responses during health and disease, with a particular focus on obesity, SDB, and its effects during early development. Obesity-induced hyperleptinemia is associated with centrally mediated hypoventilation with decrease CO₂ sensitivity. On the other hand, hyperleptinemia augments peripheral chemoreflexes to hypoxia and induces sympathoexcitation. Thus, "leptin resistance" in obesity is relative. We delineate the circuits responsible for these divergent effects, including signaling pathways. We review the unique effects of leptin during development on organogenesis, feeding behavior, and cardiorespiratory responses, and how undernutrition and overnutrition during critical periods of development can lead to cardiorespiratory comorbidities in adulthood. We conclude with suggestions for future directions to improve our understanding of leptin dysregulation and associated clinical diseases and possible therapeutic targets. Lastly, we briefly discuss the yin and the yang, specifically the contribution of relative adiponectin deficiency in adults with hyperleptinemia to the development of metabolic and cardiovascular disease. © 2020 American Physiological Society. Compr Physiol 10:1047-1083, 2020.

Effectiveness of different treatments in obesity hypoventilation syndrome

Obesity hypoventilation syndrome (OHS) is an undesirable consequence of obesity, defined as daytime hypoventilation, sleep disorder breathing and obesity; during the past few years the prevalence of extreme obesity has markedly increased worldwide consequently increasing the prevalence of OHS. Patients with OHS have a lower quality of life and a higher risk of unfavourable cardiometabolic consequences. Early diagnosis and effective treatment can lead to significant improvement in patient outcomes; therefore, such data has noticeably raised interest in the management and treatment of this sleep disorder. This paper will discuss the findings on the main current treatment modalities OHS will be discussed.

Sleep Apnea, Obesity, and Disturbed Glucose Homeostasis: Epidemiologic Evidence, Biologic Insights, and Therapeutic Strategies

PURPOSE OF REVIEW

Obstructive sleep apnea (OSA), obesity, and disturbed glucose homeostasis are usually considered distinct clinical condition, although they are tightly related to each other. The aim of our manuscript is to provide an overview of the current evidence on OSA, obesity, and disturbed glucose homeostasis providing epidemiologic evidence, biological insights, and therapeutic strategies.

RECENT FINDINGS

The mechanisms hypothesized to be involved in this complex interplay are the following: (1) "direct weight-dependent" mechanisms, according to which fat excess compromises respiratory mechanics, and (2) "indirect weight-dependent" mechanisms such as hyperglycemia, insulin resistance and secondary hyperinsulinemia, leptin resistance and other hormonal dysregulations frequently found in subjects with obesity, type 2 diabetes, and/or sleep disorders. Moreover, the treatment of each of these clinical conditions, through weight loss induced by diet or bariatric surgery, the use of anti-obesity or antidiabetic drugs, and continuous positive airway pressure (CPAP), seems to positively influence the others. These recent data suggest not only that there are multiple connections among these diseases but also that treating one of them may result in an improvement of the others.

Obstructive sleep apnea and dyslipidemia: from animal models to clinical evidence

Lipid metabolism deregulation constitutes the pathogenic basis for the development of atherosclerosis and justifies a high incidence of cardiovascular-related morbidity and mortality. Some data suggest that dyslipidemia may be associated with sleep-disordered breathing, mainly obstructive sleep apnea (OSA), due to alterations in fundamental biochemical processes, such as intermittent hypoxia (IH). The aim of this systematic review was to identify and critically evaluate the current evidence supporting the existence of a possible relationship between OSA and alterations in lipid metabolism. Much evidence shows that, during the fasting state, OSA and IH increase lipid delivery from the adipose tissue to the liver through an up-regulation of the sterol regulatory element-binding protein-1 and stearoyl-CoA desaturase-1, increasing the synthesis of cholesterol esters and triglycerides. In the postprandial state, lipoprotein clearance is delayed due to lower lipoprotein lipase activity, probably secondary to IH-up-regulation of angiopoietin-like protein 4 and decreased activity of the peroxisome proliferator-activated receptor alpha. Moreover, oxidative stress can generate dysfunctional oxidized lipids and reduce the capacity of high-density lipoproteins (HDL) to prevent low-density lipoprotein (LDL) oxidation. In the clinical field, several observational studies and a meta-regression analysis support the existence of a link between OSA and dyslipidemia. Although there is evidence of improved lipid profile after apnea-hypopnea suppression with continuous positive airway pressure (CPAP), the majority of the data come from observational studies. In contrast, randomized controlled trials evaluating the effects of CPAP on lipid metabolism present inconclusive results and two meta-analyses provide contradictory evidence.

Intranasal Leptin Relieves Sleep-disordered Breathing in Mice with Diet-induced Obesity

RATIONALE

Leptin treats upper airway obstruction and alveolar hypoventilation in leptin-deficient ob/ob mice. However, obese humans and mice with diet-induced obesity (DIO) are resistant to leptin because of poor permeability of the blood-brain barrier. We propose that intranasal leptin will bypass leptin resistance and treat sleep-disordered breathing in obesity.

OBJECTIVES

To assess if intranasal leptin can treat obesity hypoventilation and upper airway obstruction during sleep in mice with DIO.

METHODS

Male C57BL/6J mice were fed with a high-fat diet for 16 weeks. A single dose of leptin (0.4 mg/kg) or BSA (vehicle) were administered intranasally or intraperitoneally, followed by either sleep studies (n = 10) or energy expenditure measurements (n = 10). A subset of mice was treated with leptin daily for 14 days for metabolic outcomes (n = 20). In a separate experiment, retrograde viral tracers were used to examine connections between leptin receptors and respiratory motoneurons.

MEASUREMENTS AND MAIN RESULTS

Acute intranasal, but not intraperitoneal, leptin decreased the number of oxygen desaturation events in REM sleep, and increased ventilation in non-REM and REM sleep, independently of metabolic effects. Chronic intranasal leptin decreased food intake and body weight, whereas intraperitoneal leptin had no effect. Intranasal leptin induced signal transducer and activator of transcription 3 phosphorylation in hypothalamic and medullary centers, whereas intraperitoneal leptin had no effect. Leptin receptor-positive cells were synaptically connected to respiratory motoneurons.

CONCLUSIONS

In mice with DIO, intranasal leptin bypassed leptin resistance and significantly attenuated sleep-disordered breathing independently of body weight.

The Role of Animal Models in Developing Pharmacotherapy for Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a highly prevalent disease characterized by recurrent closure of the upper airway during sleep. It has a complex pathophysiology involving four main phenotypes. An abnormal upper airway anatomy is the key factor that predisposes to sleep-related collapse of the pharynx, but it may not be sufficient for OSA development. Non-anatomical traits, including (1) a compromised neuromuscular response of the upper airway to obstruction, (2) an unstable respiratory control (high loop gain), and (3) a low arousal threshold, predict the development of OSA in association with anatomical abnormalities. Current therapies for OSA, such as continuous positive airway pressure (CPAP) and oral appliances, have poor adherence or variable efficacy among patients. The search for novel therapeutic approaches for OSA, including pharmacological agents, has been pursued over the past years. New insights into OSA pharmacotherapy have been provided by preclinical studies, which highlight the importance of appropriate use of animal models of OSA, their applicability, and limitations. In the present review, we discuss potential pharmacological targets for OSA discovered using animal models.

Effects of OSA Surgery on Leptin and Metabolic Profiles

OBJECTIVES

This study is designed to investigate the effects of obstructive sleep apnea/hypopnea syndrome (OSA) surgery on serum leptin levels and metabolic disturbances, both of which contribute to the risk of cardiovascular diseases.

STUDY DESIGN

Case series with planned data collection.

SETTING

Tertiary referral medical center.

SUBJECTS AND METHODS

A retrospective chart review of 101 consecutive patients with OSA who refused or failed conservative therapy and who then underwent upper airway surgery for OSA treatment was conducted. The personal medical history, anthropometric measurements, subjective symptoms, and objective polysomnographic parameters and fasting morning blood samples for leptin and metabolic biomarkers measurements were collected preoperatively and at a minimum of 3 months postoperatively.

RESULTS

Eighty patients with OSA (69 men and 11 women; mean [SD] age of 42.2 [10.2] years) with complete data were included in the final analysis. At least 3 months after surgery, serum leptin, low-density lipoprotein cholesterol (LDL-C), and triglyceride levels and the mean systolic blood pressure (SBP) (night and morning) significantly decreased. According to the classical definition of surgical success, 40 subjects had successful surgery and were categorized as surgical responders, and the other 40 patients who failed surgery were categorized as surgical nonresponders. Significant reductions in serum leptin, total cholesterol, LDL-C, and triglyceride levels and improvement of mean SBP (morning) occurred in surgical responders but not in nonresponders.

CONCLUSIONS

Effective OSA surgery improves serum leptin, lipid profiles, and SBP. Further studies are needed to investigate the role of serial measurements of these biomarkers in monitoring surgical outcome of OSA treatment.

Sleep-Disordered Breathing and Peripheral Arterial Disease: Current Evidence

INTRODUCTION

Sleep-disordered breathing (SDB) is associated with atherosclerosis. Peripheral arterial disease (PAD) is a manifestation of atherosclerosis in lower extremity arteries. No systematic review addressing the relationship between PAD and SDB was found. We performed this study aimed to summarize the relationship between SDB and PAD described in current clinical studies.

MATERIAL AND METHODS

PubMed and Embase electronic databases were searched for clinical articles (published before 3 April, 2019) describing studies that evaluated the association between SDB and PAD. We showed the results involved in the association in clinical studies.

RESULTS

In total, 8 clinical studies have been included, and most of them were cross-sectional studies. Six articles demonstrated the coexistence of SDB and PAD, evidenced by high prevalence of SDB in patients with PAD and vice versa. Meanwhile, the included studies exhibited independent positive associations between SDB or sleep parameters and PAD after adjusting for multiple confounders.

CONCLUSION

From present clinical prospective, positive association between SDB and PAD was shown. More prospective, randomized controlled studies are needed to establish the cause-effect relationships involved.

Leptin and adiponectin levels in obstructive sleep apnea phenotypes

Objective: To examine the serum levels of leptin and adiponectin in different obstructive sleep apnea (OSA) phenotypes. Methods: Obese patients who were admitted to our sleep laboratory were included. All patients underwent spirometry, daytime arterial blood gas analysis, polysomnography and transthoracic echocardiography. Serum levels of adiponectin and leptin were recorded. Results: Analysis included 146 OSA patients (81 females, 65 males, age: 49.8 ± 10.7 years, body mass index: 40.3 ± 4.9 kg/m², 47.9% severe OSA, 42.5% severe obesity). Females had higher leptin and adiponectin levels (p < 0.001; p < 0.001, respectively). Leptin levels were higher in patients with severe obesity (p < 0.001). Severe OSA patients had lower leptin and adiponectin levels (p = 0.023; p = 0.035, respectively). Conclusion: Adipokine levels were different especially in OSA patients with severe obesity, female gender and severe OSA.

Additive interaction of snoring and body mass index on the prevalence of metabolic syndrome among Chinese coal mine employees: a cross-sectional study

BACKGROUND

Although snoring has been previously reported to be associated with metabolic syndrome (MetS), its interaction with body mass index(BMI) on MetS remains unclear. We aimed to examine the individual effects and possible interaction between snoring and BMI on MetS.

METHODS

From July 2013 to December 2013, 3794 employees of coal mining enterprises aged 18 to 65 were recruited from Shanxi province of China. The individual effects were assessed by multivariable logistic regression model. Additive interaction was evaluated by calculating the relative excess risk due to interaction (RERI), attributable proportion due to interaction (AP) and synergy index(S).

RESULTS

We found that, after adjusting for potential confounders, odds ratio (OR) and 95% CI for MetS was 1.30 (1.09, 1.56) in occasional snorers and 1.50 (1.24, 1.82) in habitual snorers compared with non-snorers. BMI ≥ 24 was related to high risk of MetS (OR, 3.27; 95% CI, 2.93-3.63). Significant additive interaction between snoring and BMI on MetS was detected. The estimates and 95% CI of the RERI, AP and S were 1.89 (0.67, 3.24), 0.23 (0.08, 0.38), and 1.37 (1.11, 1.75), respectively. However, stratified by workplace, the additive interaction was only significant among underground front-line and ground workers.

CONCLUSIONS

Both Snoring and BMI were related to high risk of Mets. Moreover, there are additive interaction between snoring and BMI. Snorers who worked underground front-line and ground are more susceptible to the negative impact of being overweight on MetS.

Vertical sleeve gastrectomy improves ventilatory drive through a leptin-dependent mechanism

Obesity hypoventilation syndrome (OHS) is a serious disorder characterized by daytime hypercapnia, disordered breathing, and a reduction in chemosensitivity. Vertical sleeve gastrectomy (VSG), a bariatric surgical procedure resulting in weight loss and weight-independent improvements in glucose metabolism, has been observed to substantially improve sleep-disordered breathing. However, it is unclear if the ventilatory effects of VSG are secondary to weight loss or the marked change in metabolic physiology. Using preclinical mouse models, we found that VSG leads to an improvement in the hypercapnic ventilatory response (HCVR) and reductions in circulating leptin levels independent of reductions in body mass, fat mass, and caloric intake. In the absence of leptin, VSG continues to improve body mass, fat mass, and glucose tolerance in ob/ob mice but no longer affects HCVR. However, the HCVR of ob/ob mice can be returned to wild-type levels with leptin treatment. These data demonstrate that VSG improves chemosensitivity and ventilatory drive via a leptin-dependent mechanism. Clinically, these data downgrade the relative contribution of physical, mechanical load in the pathogenesis of OHS, and instead point to physiological components of obesity, including alterations in leptin signaling, as key drivers in OHS.

Indicadores de adiposidade como método de rastreamento para polissonografia em trabalhadores de turno

Resumo Objetivo: verificar o potencial discriminatório dos indicadores de adiposidade na predição da apneia obstrutiva do sono (AOS) em trabalhadores de turnos. Métodos: estudo transversal realizado em uma empresa de extração de minério de ferro, em Minas Gerais, Brasil. Dados antropométricos foram coletados e polissonografia (PSG) foi realizada em 118 trabalhadores de turno do sexo masculino que possuíam ao menos um fator de risco global para doença cardiovascular. Resultados: a prevalência de AOS na amostra foi de 84,7%. Entre os indicadores de adiposidade usados para predizerem a AOS (≥ 5 eventos/hora), o índice de massa corporal (IMC), a circunferência da cintura (CC), a relação cintura/estatura (RCE) e a gordura corporal total (GCT), revelaram valores de sensibilidade acima de 70%. Gordura visceral (GV), circunferência do pescoço (CP) e relação pescoço-estatura (RPE) foram as mais efetivas em identificar corretamente trabalhadores sem AOS (valores de especificidade acima de 70%). As áreas sob a curva de Característica de Operação do Receptor (COR) para CC e RPE foram maiores que 0,7, o que indicou que o teste foi eficaz na discriminação de indivíduos com AOS. Conclusões: alterações nos indicadores de adiposidade abdominal e cervical têm relação significativa com a presença de AOS e demostraram eficácia como método de rastreamento para PSG. CC e RPE são considerados bons indicadores para predizerem a AOS.

The Bidirectional Relationship Between Obstructive Sleep Apnea and Metabolic Disease

Obstructive sleep apnea (OSA) is a common sleep disorder, effecting 17% of the total population and 40-70% of the obese population (1, 2). Multiple studies have identified OSA as a critical risk factor for the development of obesity, diabetes, and cardiovascular diseases (3-5). Moreover, emerging evidence indicates that metabolic disorders can exacerbate OSA, creating a bidirectional relationship between OSA and metabolic physiology. In this review, we explore the relationship between glycemic control, insulin, and leptin as both contributing factors and products of OSA. We conclude that while insulin and leptin action may contribute to the development of OSA, further research is required to determine the mechanistic actions and relative contributions independent of body weight. In addition to increasing our understanding of the etiology, further research into the physiological mechanisms underlying OSA can lead to the development of improved treatment options for individuals with OSA.

Role of Leptin in Obstructive Sleep Apnea

Leptin is a peptide hormone produced mainly in white adipose tissue. It is known to regulate energy homeostasis, inflammation, metabolism, and sympathetic nerve activity. Increasing evidence suggests it has a role in ventilatory function and upper airway obstruction. Leptin levels correlate positively with measurements of adiposity and can potentially provide important insights into the pathophysiology of diseases associated with obesity. Obesity is a strong risk factor for obstructive sleep apnea, a disease characterized by periodic upper airway occlusion during sleep. The neuromuscular activity that maintains upper airway patency during sleep and the anatomy of upper airway are key factors involved in its pathogenesis. Experimental studies using animal models of a low leptin state such as leptin deficiency have shown that leptin regulates sleep architecture, upper airway patency, ventilatory function, and hypercapnic ventilatory response. However, findings from human studies do not consistently support the data from the animal models. The effect of leptin on the pathophysiology of obstructive sleep apnea is being investigated, but the results of studies have been confounded by leptin's diurnal variation and the short-term effects of feeding, adiposity, age, and sex. Improved study design and methods of assessing functional leptin levels, specifically their central versus peripheral effects, will improve understanding of the role of leptin in sleep apnea.

Gestational Hypoxia and Developmental Plasticity

Hypoxia is one of the most common and severe challenges to the maintenance of homeostasis. Oxygen sensing is a property of all tissues, and the response to hypoxia is multidimensional involving complicated intracellular networks concerned with the transduction of hypoxia-induced responses. Of all the stresses to which the fetus and newborn infant are subjected, perhaps the most important and clinically relevant is that of hypoxia. Hypoxia during gestation impacts both the mother and fetal development through interactions with an individual's genetic traits acquired over multiple generations by natural selection and changes in gene expression patterns by altering the epigenetic code. Changes in the epigenome determine "genomic plasticity," i.e., the ability of genes to be differentially expressed according to environmental cues. The genomic plasticity defined by epigenomic mechanisms including DNA methylation, histone modifications, and noncoding RNAs during development is the mechanistic substrate for phenotypic programming that determines physiological response and risk for healthy or deleterious outcomes. This review explores the impact of gestational hypoxia on maternal health and fetal development, and epigenetic mechanisms of developmental plasticity with emphasis on the uteroplacental circulation, heart development, cerebral circulation, pulmonary development, and the hypothalamic-pituitary-adrenal axis and adipose tissue. The complex molecular and epigenetic interactions that may impact an individual's physiology and developmental programming of health and disease later in life are discussed.

Treating Obstructive Sleep Apnea and Chronic Intermittent Hypoxia Improves the Severity of Nonalcoholic Fatty Liver Disease in Children

OBJECTIVE

To determine the effects of treating obstructive sleep apnea/nocturnal hypoxia on pediatric nonalcoholic fatty liver disease (NAFLD) severity and oxidative stress.

STUDY DESIGN

Biopsy proven participants (n = 9) with NAFLD and obstructive sleep apnea/hypoxia were studied before and after treatment with continuous positive airway pressure (CPAP) for sleep disordered breathing, including laboratory testing and markers of oxidative stress, urine F(2)-isoprostanes.

RESULTS

Adolescents (age 11.5 ± 1.2 years; body mass index, 29.5 ± 3.8 kg/m²) with significant NAFLD (mean histologic necroinflammation grade, 2.3 ± 0.9; fibrosis stage, 1.4 ± 1.3; NAFLD Activity Score summary, 4.8 ± 1.6) had obstructive sleep apnea/hypoxia by polysomnography. At baseline, they had severe obstructive sleep apnea/hypoxia, elevated aminotransferases, the metabolic syndrome, and significant oxidative stress (high F(2)-isoprostanes). Obstructive sleep apnea/hypoxia was treated with home CPAP for a mean 89 ± 62 days. Although body mass index increased, obstructive sleep apnea/hypoxia severity improved on CPAP and was accompanied by reduced alanine aminotransferase, metabolic syndrome markers, and F(2)-isoprostanes.

CONCLUSIONS

This study provides strong evidence that treatment of obstructive sleep apnea/nocturnal hypoxia with CPAP in children with NAFLD may reverse parameters of liver injury and reduce oxidative stress. These data also suggest CPAP as a new therapy to prevent progression of NAFLD in those children with obesity found to have obstructive sleep apnea/nocturnal hypoxia.

The effect of relaxation exercises on sleep quality in pregnant women in the third trimester: A randomized controlled trial

OBJECTIVE

To assess the effects of relaxation exercises on subjective sleep quality of in third-trimester pregnant women.

MATERIALS AND METHODS

The pretest posttest randomized controlled trial recruited 84 pregnant women in the third trimester. Following random assignment of subjects, the treatment group (n = 46) performed relaxation exercises for four weeks and the control group (n = 46) received standart cares. At baseline and after the intervention sleep quality was assessed. Data obtained were analyzed in SPSS.

RESULTS

The mean score of the global Pittsburgh Sleep Quality Index was 7.12 ± 3.66. It was determined that relaxation exercises improved some sleep quality subscales including subjective sleep quality, sleep latency, sleep duration and habitual sleep efficiency, sleep disturbances, daytime dysfunction and global sleep quality. The difference between the two groups was found to be statistically significant (p < 0.05).

CONCLUSION

A four -week compact disc guide relaxation exercises program can be effective in improving sleep quality.

Continuous Positive Airway Pressure Reduces Night-Time Blood Pressure and Heart Rate in Patients With Obstructive Sleep Apnea and Resistant Hypertension: The RHOOSAS Randomized Controlled Trial

Objective

Most patients with resistant hypertension (RH) have obstructive sleep apnea (OSA). We aimed to determine the impact of OSA and continuous positive airway pressure (CPAP) treatment on the leptin profile and blood pressure (BP) in patients with RH.

Methods

After an initial case-control study (RH with and without OSA), we performed a randomized, single blind study in OSA + RH patients receiving either sham CPAP (3 months) followed by active CPAP (6 months) or 6 months of active CPAP. The primary outcome was the comparison of leptin levels between groups of RH patients with or without OSA. Secondary outcomes were the comparison of metabolic parameters, biomarkers of sympathetic activity, and BP indices between the two groups of RH patients with or without OSA. The same outcomes were then evaluated and compared before and after sham and effective CPAP intervention.

Results

Sixty-two patients (60 ± 10 years; 77% men) with RH (24-h daytime systolic BP (SBP)/diastolic BP: 145 ± 13/85 ± 10 mmHg, 3.7 antihypertensive drugs) were included. The 37 RH patients exhibiting OSA (60%) were predominantly men (87 vs 64% for non-OSA patients), with a greater prevalence of metabolic syndrome and higher creatininemia. Their leptin concentrations were significantly lower than in non-OSA patients [9 (6; 15) vs 17 (6; 29) ng/mL] but increased after 6 months of CPAP. Three months of effective CPAP significantly decreased night-time SBP by 6.4 mmHg and heart rate (HR) by 6.0 bpm, compared to sham CPAP.

Conclusion

The association between OSA and RH corresponds to a specific, predominately male phenotype with a higher burden of metabolic syndrome and higher creatininemia but there was no significant difference between OSA and non-OSA patients regarding BP indices, and the number of antihypertensive drugs used. Active CPAP could be efficient at decreasing night-time BP and HR, but there was no difference between CPAP and sham CPAP groups for all metabolic and SNS markers (NCT00746902 RHOOSAS).

Effects of small interfering RNA targeting TLR4 on expressions of adipocytokines in obstructive sleep apnea hyponea syndrome with hypertension in a rat model

We explored the effects of RNA interference-mediated silencing of TLR4 gene on expressions of adipocytokines in obstructive sleep apnea hyponea syndrome (OSAS) with hypertension in a rat model. Systolic blood pressure of caudal artery and physiological changes were observed when establishing rat models of OSAS with hypertension. Mature rat adipocytes were induced from separated and cultured primary rat adipocytes. To transfect rat mature adipocytes, TLR4 siRNA group and negative control (NC) siRNA group were established. Expressions of TLR4 mRNA of adipocytes were examined after silenced by siRNA by quantitative real-time polymerase chain reaction (qRT-PCR). By enzyme-linked immunosorbent assay (ELISA), expressions of inflammatory cytokines, and adipocytokines of adipocytes were detected. Blood pressure in rat caudal artery was higher in the intermittent hypoxia group than that of the blank control group by 29.87 mmHg, and cardiocytes in the former group showed physiological changes, which indicated successful establishment of rat models of OSAS with hypertension. Red particles could be seen in mature rat adipocytes when stained with Oil Red O. Transfection of TLR4 mRNA was significantly suppressed in the TLR4 siRNA group, which didn't happen in the untransfected control group. Rats in the TLR4 siRNA group had significantly reduced expressions of such inflammatory cytokines as interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-α (TNF-α) and such adipocytokines as visfatin, adiponectin (ADN), and leptin than those in the untransfected control group. RNA interference-mediated silencing of TLR4 gene could regulate occurrence and development of OSAS with hypertension in rats by downregulating expressions of adipocytokines.

Association of obstructive sleep apnea with microvascular endothelial dysfunction and subclinical coronary artery disease in a community-based population

Studies have reported an association between obstructive sleep apnea (OSA) and cardiovascular disease (CVD) morbidity and mortality. Proposed mechanisms include endothelial dysfunction and atherosclerosis. We aimed to investigate the associations of OSA with endothelial dysfunction and subclinical atherosclerotic coronary artery disease (CAD), and assess the impact of race on these associations. We used data from the Heart Strategies Concentrating on Risk Evaluation (Heart SCORE) study, a community-based prospective cohort with approximately equal representation of black and white participants. OSA severity was measured in 765 individuals using the apnea-hypopnea index (AHI). Endothelial dysfunction was measured using the Endo-PAT device, expressed as Framingham reactive hyperemia index (F_RHI). Coronary artery calcium (CAC), a marker of subclinical CAD, was quantified by electron beam computed tomography. There were 498 (65%) female participants, 282 (37%) black individuals, and 204 (26%) participants with moderate/severe OSA (AHI ≥15). In univariate models, moderate/severe OSA was associated with lower F_RHI and higher CAC, as well as several traditional CVD risk factors including older age, male sex, hypertension, diabetes, higher body mass index, and lower high-density lipoprotein cholesterol levels. In a multivariable model, individuals with moderate/severe OSA had 10% lower F_RHI and 35% higher CAC, which did not reach statistical significance ( p=0.08 for both comparisons). There was no significant interaction of race on the association of OSA with F_RHI or CAC ( p-value >0.1 for all comparisons). In a community-based cohort comprised of black and white participants, moderate/severe OSA was modestly associated with endothelial dysfunction and subclinical atherosclerotic CAD. These associations did not vary by race.

Effect of CPAP therapy on liver disease in patients with OSA: a review

Obstructive sleep apnea (OSA) may play an important role in the progression of nonalcoholic fatty liver disease (NAFLD).The effect of continuous positive airway pressure (CPAP) treatment, the first-line therapy for OSA, on liver disease in OSA patients is still debated. We provide this review of previous studies to summarize the effects of CPAP treatment on liver disease in OSA patients in aspects of liver function, liver steatosis, fibrosis, and incidence of liver disease. CPAP treatment may be beneficial to liver disease in subjects with OSA independent of metabolic risk factors, but a sufficiently long therapeutic duration (perhaps greater than 3 months) may be needed to achieve these positive effects. Though the mechanism of impact of CPAP treatment on liver in OSA patients is unclear, the influence of CPAP treatment on the factors of the "Two-hit" hypothesis (insulin resistance, fatty acids dysregulation, oxidative stress, and inflammation) may be a reasonable explanation.

Neuropeptides and breathing in health and disease

Regulatory neuropeptides control and regulate breathing in physiological and pathophysiological conditions. While they have been identified in the neurons of major respiratory areas, they can be active not only at the central level, but also at the periphery via chemoreceptors, vagal afferents, or locally within lungs and airways. Some neuropeptides, such as leptin or substance P, are respiratory stimulants; others, such as neurotensin, produce variable effects on respiration depending on the site of application. Some neuropeptides have been implicated in pathological states, such as obstructive sleep apnea or asthma. This article provides a concise review of the possible role and functions of several selected neuropeptides in the process of breathing in health and disease and in lung pathologies.

Association of Mild Obstructive Sleep Apnea With Cognitive Performance, Excessive Daytime Sleepiness, and Quality of Life in the General Population: The Korean Genome and Epidemiology Study (KoGES)

Study Objectives

Research points to impaired cognitive performance in sleep clinic patients with obstructive sleep apnea (OSA). However, inconsistent findings from various epidemiologic studies make this relationship less generalizable. The current study investigated the association between OSA and functional outcome measures, such as cognition, daytime sleepiness, and quality of life, in a Korean general population sample.

Methods

A total of 1492 participants from the Korean Genome and Epidemiology Study (KoGES) were included in the analyses. The presence of OSA measured by overnight polysomnography (PSG) was defined by apnea-hypopnea index (AHI) >5. Cognitive performance was determined with scores from a comprehensive neuropsychological battery. Excessive daytime sleepiness and quality of life were additionally measured through subjective reports.

Results

After adjusting for various demographic and medical characteristics, OSA was independently associated with lower performance in the Digit Symbol Test (52.73 ± 17.08 vs. 58.72 ± 18.03, OSA vs. not, p = .02). Hypoxia measures were not related to cognitive performance. OSA was associated with higher odds of displaying excessive daytime sleepiness (odds ratio = 1.72, 95% CI: 1.05-2.80), but there was no significant relationship between OSA and quality of life.

Conclusions

Cognition was unexpectedly unaffected overall. However, OSA was associated with impairment in a multidomain test that taps skills generally associated with frontal lobe function. The results suggest that research on protective and adaptive brain mechanisms to OSA stress can provide unique insights into the brain-sleep interface. As the study runs longitudinally, it will enable future studies on the impact of OSA on cognitive decline.