Effect of weight loss on inflammation in patients with mild obstructive sleep apnea

Weight Loss and Sleep, Current Evidence in Animal Models and Humans

Sleep is a vital process essential for survival. The trend of reduction in the time dedicated to sleep has increased in industrialized countries, together with the dramatic increase in the prevalence of obesity and diabetes. Short sleep may increase the risk of obesity, diabetes and cardiovascular disease, and on the other hand, obesity is associated with sleep disorders, such as obstructive apnea disease, insomnia and excessive daytime sleepiness. Sleep and metabolic disorders are linked; therefore, identifying the physiological and molecular pathways involved in sleep regulation and metabolic homeostasis can play a major role in ameliorating the metabolic health of the individual. Approaches aimed at reducing body weight could provide benefits for both cardiometabolic risk and sleep quality, which indirectly, in turn, may determine an amelioration of the cardiometabolic phenotype of individuals. We revised the literature on weight loss and sleep, focusing on the mechanisms and the molecules that may subtend this relationship in humans as in animal models.

The Influence of Comorbidities on Chemokine and Cytokine Profile in Obstructive Sleep Apnea Patients: Preliminary Results

INTRODUCTION

Obstructive sleep apnea (OSA) is frequently associated with a chronic inflammatory state and cardiovascular/metabolic complications. The aim of this study was to evaluate the influence of certain comorbidities on a panel of 45 chemokines and cytokines in OSA patients with special regard to their possible association with cardiovascular diseases.

MATERIAL AND METHODS

This cross-sectional study was performed on 61 newly diagnosed OSA patients. For the measurement of the plasma concentration of chemokines and cytokines, the magnetic bead-based multiplex assay for the Luminex^® platform was used.

RESULTS

In the patients with concomitant COPD, there were increased levels of pro-inflammatory cytokines (CCL11, CD-40 ligand) and decreased anti-inflammatory cytokine (IL-10), while in diabetes, there were increased levels of pro-inflammatory cytokines (IL-6, TRIAL). Obesity was associated with increased levels of both pro-inflammatory (IL-13) and anti-inflammatory (IL-1RA) cytokines. Hypertension was associated with increased levels of both pro-inflammatory (CCL3) and anti-inflammatory (IL-10) cytokines. Increased daytime pCO₂, low mean nocturnal SaO₂, and the oxygen desaturation index were associated with increased levels of pro-inflammatory cytokines (CXCL1, PDGF-AB, TNF-α, and IL-15).

CONCLUSIONS

In OSA patients with concomitant diabetes and COPD, elevated levels of certain pro-inflammatory and decreased levels of certain anti-inflammatory cytokines may favor the persistence of a chronic inflammatory state with further consequences. Nocturnal hypoxemia, frequent episodes of desaturation, and increased daytime pCO₂ are factors contributing to the chronic inflammatory state in OSA patients.

Inflammatory cytokines and sleep parameters response to life style intervention in subjects with obese chronic insomnia syndrome

Background

Chronic primary insomnia is a prevalent sleep disorder that is associated with adverse effects on health outcomes. Sleep disturbance is usually associated with abnormal level of systemic inflammation biomarkers.

Objective

The aim of this study was to detect changes in sleep quality and inflammatory markers following weight loss among subjects with chronic primary insomnia.

Material and methods

Eighty previously sedentary subjects with chronic primary insomnia subjects enrolled in this study, their age ranged from 32–51 year were randomly assigned to life style intervention group (group A, n=40) or control group (group B, n=40). Polysomnographic recordings for sleep quality assessment, IL-6, IL-10 and TNF-α were measured before and at the end of the study after six months.

Results

There was a significant increase in the total sleep duration, sleep efficiency, sleep onset latency and IL-10 in addition to significant reduction in awake time after sleep onset, REM latency, IL-6 and TNF-α after 6 months of in group(A) as a result of weight loss program; while the results of the control group (group B) were not significant. Also, there were significant differences between both groups at the end of the study.

Conclusion

Life style intervention modulates systemic inflammatory parameters and sleep quality among subjects with chronic primary insomnia.

The treatment of mild OSA with CPAP or mandibular advancement device and the effect on blood pressure and endothelial function after one year of treatment

STUDY OBJECTIVES

To evaluate and compare the effects of continuous positive airway pressure (CPAP), use of a mandibular advancement device (MAD), and no treatment on 24-hour ambulatory blood pressure monitoring and peripheral arterial tonometry at 6 and 12 months follow-up in individuals with mild obstructive sleep apnea (OSA), and in a subgroup who had an apnea-hypopnea index of < 5 events/h and adherence of ≥ 4 hours per night (effective-treatment subgroups).

METHODS

The inclusion criteria were individuals with mild obstructive sleep apnea, any sex, age between 18 and 65 years, and a body mass index of ≤ 35 kg/m². Patients were randomized into CPAP, MAD, and no-treatment groups. The evaluations included physical examination, full polysomnography, 24-hour ambulatory blood pressure monitoring, and peripheral arterial tonometry at baseline and after 6 and 12 months. A generalized linear mixed model was used for comparisons.

RESULTS

The CPAP and MAD groups had lower apnea-hypopnea indexes than the control group at 6 and 12 months, and the CPAP group had higher blood oxygen levels (SpO₂) than the MAD group. The MAD group had more hours of treatment per night and better adaptation to treatment than the CPAP group (MAD: 5.7 ± 2.7 h/night; CPAP: 3.8 ± 3.4 h/night; MAD: 16% did not adapt; CPAP: 42% did not adapt). No differences were found in the total sample and effective treatment in relation to peripheral arterial tonometry or 24-hour ambulatory blood pressure monitoring outcomes.

CONCLUSIONS

Treatment of mild obstructive sleep apnea with CPAP or MAD did not improve blood pressure or endothelial function after 1 year, even in patients with effective treatment.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Continuous Positive Airway Pressure and Oral Appliances Treatments in Mild Obstructive Sleep Apnea; URL: https://clinicaltrials.gov/ct2/show/NCT01461486; Identifier: NCT01461486.

Use of polysomnography and home sleep apnea tests for the longitudinal management of obstructive sleep apnea in adults: an American Academy of Sleep Medicine clinical guidance statement

INTRODUCTION

Obstructive sleep apnea is an important and common disorder with associated health risks. Assuring successful longitudinal management is vital to patient health and sleep-related quality of life. This paper provides guidance from the American Academy of Sleep Medicine (AASM) regarding the use of polysomnography (PSG) and home sleep apnea tests (HSATs) after a diagnosis of obstructive sleep apnea has been established and, in most cases, treatment implemented.

METHODS

The AASM commissioned a task force of five sleep medicine experts. A literature search was conducted to identify studies that included adult patients with OSA who underwent follow-up PSG or an HSAT. The task force developed clinical guidance statements based on a review of these studies and expert opinion. The AASM Board of Directors approved the final clinical guidance statements.

CLINICAL GUIDANCE STATEMENTS

The AASM supports the following clinical guidance statements on indications for follow-up PSG and HSAT in adult patients with OSA. 1. Follow-up PSG or HSAT is not recommended for routine reassessment of asymptomatic patients with obstructive sleep apnea on PAP therapy, however, follow-up PSG or HSAT can be used to reassess patients with recurrent or persistent symptoms, despite good PAP adherence. 2. Follow-up PSG or HSAT is recommended to assess response to treatment with non-PAP interventions. 3. Follow-up PSG or HSAT may be used if clinically significant weight gain or loss has occurred since diagnosis of OSA or initiation of its treatment. 4. Follow-up PSG may be used for reassessment of sleep-related hypoxemia and/or sleep-related hypoventilation following initiation of treatment for OSA. 5. Follow-up PSG or HSAT may be used in patients being treated for OSA who develop or have a change in cardiovascular disease. 6. Follow-up PSG may be used in patients with unexplained PAP device-generated data. The ultimate judgment regarding propriety of any specific care must be made by the clinician, in light of the individual circumstances presented by the patient, available diagnostic tools, accessible treatment options and resources.

One-month of a low-energy diet, with no additional effect of high-protein, reduces Obstructive Sleep Apnea severity and improve metabolic parameters in obese males

PURPOSE

Obstructive Sleep Apnea (OSA) is closely associated with obesity. Weight loss ameliorates OSA and its associated metabolic disorders. A high protein intake may improve weight loss through increased energy expenditure, and fat-free mass maintenance during weight loss.

OBJECTIVES

To evaluate the effects of a low-energy, high-protein diet on OSA severity and metabolic parameters in obese men.

METHODS

Forty-five OSA obese (BMI ≥ 30 kg/m²) males were included in this randomized study and submitted to nocturnal polysomnography, body composition measured by plethysmography, biochemical analyses of blood glucose, insulin and lipids, and food intake evaluations before and after one month of a low-energy diet. Diets were designed to create a 30% deficit in total energy expenditure with 1.6 g of protein/kg/day (High Protein group - HP) or 0.8 g of protein/kg/day (Low Protein group - LP).

RESULTS

Only a time effect of the intervention was observed in body mass (-3.7 ± 2.0% for the LP group and -4.0 ± 1.5% for the HP group; p < 0.001), Body Mass Index (p < 0.001), fat mass in kg (p < 0.01) and fat-free mass in kg (p < 0.01). Significant improvements in Apnea Hypopnea Index were observed in both groups (54.0 ± 25.0 to 33.7 ± 31.7 in LP group; 39.7 ± 24.3 to 21.4 ± 25.9 in HP group; p = 0.06). Improvements of 38% and 46% in the Apnea-Hypopnea Index were observed in the LP and HP groups, respectively. Both interventions provided equivalent metabolic benefits as reductions in glucose (p < 0.001), insulin (p < 0.001), HOMA-IR (p = 0.005), triglycerides (p = 0.002), and in total cholesterol (p = 0.004).

CONCLUSION

One month of a low-energy diet resulted in significant improvements in OSA severity in obese men. Increased protein intake during a short period of low-energy diet had no further beneficial effects on OSA severity or biochemical parameters than a standard protein diet. Registered under ClinicalTrials.gov Identifier no. NCT01985035.

Recent Advances in Studies on the Role of Neuroendocrine Disorders in Obstructive Sleep Apnea-Hypopnea Syndrome-Related Atherosclerosis

Cardiovascular disease is a common cause of death worldwide, and atherosclerosis (AS) and obstructive sleep apnea-hypopnea syndrome (OSAHS) critically contribute to the initiation and progression of cardiovascular diseases. OSAHS promotes endothelial injury, vascular smooth muscle cell (VSMC) proliferation, abnormal lipid metabolism, and elevated arterial blood pressure. However, the exact OSAHS mechanism that causes AS remains unclear. The nervous system is widely distributed in the central and peripheral regions. It regulates appetite, energy metabolism, inflammation, oxidative stress, insulin resistance, and vasoconstriction by releasing regulatory factors and participates in the occurrence and development of AS. Studies showed that OSAHS can cause changes in neurophysiological plasticity and affect modulator release, suggesting that neuroendocrine dysfunction may be related to the OSAHS mechanism causing AS. In this article, we review the possible mechanisms of neuroendocrine disorders in the pathogenesis of OSAHS-induced AS and provide a new basis for further research on the development of corresponding effective intervention strategies.

Impaired sustained attention and lapses are present in patients with mild obstructive sleep apnea

BACKGROUND

Severe obstructive sleep apnea (OSA) directly affects the quality of life, mood, and sustained attention of individuals, but it has not yet been established in the literature, if these changes also affect patients with mild OSA. The purpose of this study was to investigate such negative effects on the parameters described above.

METHODS

A controlled study was held at the Universidade Federal de Sao Paulo, Department of Psychobiology. Thirty-nine mild OSA patients and 25 controls were included. Volunteers could be of both genders with body mass index (BMI) ≤35 kg/m(2) and age between 18 and 65 years. Both groups were subjected to full-night polysomnography (PSG), the subjective assessment of mood (Beck Inventory of Anxiety and Depression), Functional Outcomes of Sleep Questionnaire (FOSQ), and the psychomotor vigilance task (PVT) five times during the day. We considered mild OSA patients those with apnea-hypopnea index (AHI) score between 5 and 15. The control group included subjects with AHI scores <5, respiratory disturbance index (RDI) scores ≤5, arousal index values ≤15, and Epworth Sleepiness Scale (ESS) values ≤9.

RESULTS

Mild OSA patients were older and more obese than the controls. After adjusting for age, BMI, and schooling years, there was an increased number of total lapses (3.90 ± 4.16 and 2.43 ± 5.55, p = 0.004).

CONCLUSIONS

Patients with mild OSA showed increased sustained attention lapses compared with normal subjects.

Prolonged REM sleep restriction induces metabolic syndrome-related changes: Mediation by pro-inflammatory cytokines

Chronic sleep restriction in human beings results in metabolic abnormalities, including changes in the control of glucose homeostasis, increased body mass and risk of cardiovascular disease. In rats, 96h of REM sleep deprivation increases caloric intake, but retards body weight gain. Moreover, this procedure increases the expression of pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), which may be involved with the molecular mechanism proposed to mediate insulin resistance. The goal of the present study was to assess the effects of a chronic protocol of sleep restriction on parameters of energy balance (food intake and body weight), leptin plasma levels and its hypothalamic receptors and mediators of the immune system in the retroperitoneal adipose tissue (RPAT). Thirty-four Wistar rats were distributed in control (CTL) and sleep restriction groups; the latter was kept onto individual narrow platforms immersed in water for 18h/day (from 16:00h to 10:00h), for 21days (SR21). Food intake was assessed daily, after each sleep restriction period and body weight was measured daily, after the animals were taken from the sleep deprivation chambers. At the end of the 21day of sleep restriction, rats were decapitated and RPAT was obtained for morphological and immune functional assays and expression of insulin receptor substrate 1 (IRS-1) was assessed in skeletal muscle. Another subset of animals was used to evaluate blood glucose clearance. The results replicated previous findings on energy balance, e.g., increased food intake and reduced body weight gain. There was a significant reduction of RPAT mass (p<0.001), of leptin plasma levels and hypothalamic leptin receptors. Conversely, increased levels of TNF-α and IL-6 and expression of phosphorylated NFκ-β in the RPAT of SR21 compared to CTL rats (p<0.01, for all parameters). SR21 rats also displayed reduced glucose clearance and IRS-1 expression than CTL rats (p<0.01). The present results indicated that 21days of sleep restriction by the platform method induced metabolic syndrome-related alterations that may be mediated by inflammation of the RPAT.

Diet, inflammation and prediabetes-impact of quality of diet

Low grade inflammation has been linked to risk of type 2 diabetes and atherosclerotic vascular diseases. Obesity and, in particular, abdominal obesity increase the risk of diabetes and atherosclerotic vascular diseases. One of the mechanisms could be low grade inflammation and vascular endothelial dysfunction. Permanent weight reduction is the first line of treatment both for obese individuals at increased risk of diabetes and for newly onset type 2 diabetes. Weight reduction lowers the level of several inflammatory factors in the body while increasing the level of adiponectin. Besides weight reduction the quality of diet and physical activity also modifies low grade inflammation. Based on the literature survey and our own studies in humans, it is possible to have dietary patterns that reduce inflammatory stress in the body and improves vascular endothelial dysfunction. There is strong evidence to suggest that IL-1 Ra is a very sensitive marker of low grade inflammation in obesity and related phenotypes; however, its level is markedly lowered by weight reduction and by choosing foods that have been shown to reduce inflammatory stress in the body.

The impact of pharyngeal fat tissue on the pathogenesis of obstructive sleep apnea

PURPOSE

Obesity is the most important risk factor for obstructive sleep apnea (OSA); however, the exact underlying mechanisms are still not fully understood. The aim of this study was to examine the morphology of upper airways in overweight habitual snorers and in mild OSA patients. Furthermore, the associations between weight loss, parapharyngeal fat pad area and OSA were assessed in a 1-year randomised, controlled follow-up study originally conducted to determine the effects of lifestyle changes with weight reduction as a treatment of OSA.

METHODS

Thirty-six overweight adult patients with mild OSA [apnea-hypopnea index (AHI) 5-15 events/h] and 24 weight-matched habitual snorers (AHI < 5 events/h) were included in the study. All patients underwent nocturnal cardiorespiratory recordings and multislice computed tomography (CT) of parapharyngeal fat pad area, the smallest diameter and area in naso-, oro- and hypopharynx, the smallest diameter and area of the whole pharyngeal airway, the distance from the hyoid bone to the mandibular plane and to cervical tangent as well as the distance between mandibular symphysis and cervical spine. In addition, OSA patients were further randomised to receive either an active 1-year lifestyle intervention with an early weight loss programme or routine lifestyle counselling. After 1 year, the cardiorespiratory recordings and CT scans were repeated.

RESULTS

The pharyngeal fat pad area was significantly larger, and the distance from the hyoid bone to cervical spine was longer in patients with OSA than in habitual snorers (p = 0.002 and p = 0.018, respectively). The multiple regression analysis showed that besides a large pharyngeal fat pad area and a long distance from the cervical spine to hyoid bone, also a short distance from the mandibular symphysis to cervical tangent increased a risk to OSA. During the 1-year follow-up in OSA patients, the pharyngeal fat pad area and AHI decreased significantly in the intervention group (p = 0.003 and p < 0.001, respectively).

CONCLUSIONS

In the early stages of OSA, the pharyngeal fat pad seems to play an important role in the development of disease in overweight patients. Furthermore, weight reduction by lifestyle intervention-based programme reduces both central obesity and pharyngeal fat pads, resulting in an improvement of OSA.

Endothelial function is well preserved in obese patients with mild obstructive sleep apnea

PURPOSE

Endothelial dysfunction is one of the early markers of cardiovascular complications in obstructive sleep apnea (OSA). The aim of our study was to evaluate whether overweight patients with mild OSA displayed endothelial dysfunction, and to assess the effect of 1-year lifestyle intervention with an early very low calorie diet in endothelial function.

METHODS

At baseline, the study population consisted of 83 overweight patients with mild OSA and 46 weight-matched non-OSA subjects. OSA patients were further randomized into a 1-year supervised lifestyle intervention group or control group which received routine lifestyle counselling. Endothelial function measured by brachial artery flow-mediated dilatation (FMD), apnea-hypopnea index (AHI), body mass index (BMI), and metabolic parameters were assessed at baseline and 12 months.

RESULTS

No correlations between endothelial function and mild OSA were detected. However, patients with impaired endothelial function had lower mean saturation and impaired endothelial function correlated significantly with glucose intolerance and dyslipidemia. After the lifestyle intervention and successful weight reduction, AHI, BMI, serum triglycerides and insulin improved significantly; however, no improvement in FMD was detected.

CONCLUSIONS

Mild OSA was not observed to be associated with endothelial dysfunction. Although in mild OSA endothelial function is still preserved, lifestyle intervention with weight reduction did achieve an improvement in other obesity-related risk factors for cardiovascular diseases, thus highlighting the importance of early intervention.

Effects of dietary weight loss on obstructive sleep apnea: a meta-analysis

PURPOSE

Clinical and epidemiologic investigations suggest a strong association between obesity and obstructive sleep apnea (OSA). The purpose of this study is to evaluate the currently available literature reporting on the effectiveness of dietary weight loss in treating OSA among obese patients.

METHODS

Relevant studies were identified by computerized searches of PubMed, EMBASE, CINAHL, Web of Science, and The Cochrane Central Register of Controlled Trials through September 2011 as well as the reference lists of all obtained articles. Information on study design, patient characteristics, pre- and post-dietary weight loss measures of OSA and body mass index (BMI), and study quality was obtained. Data were extracted by two independent analysts. Weighted averages using a random-effects model are reported with 95 % confidence intervals.

RESULTS

Nine articles representing 577 patients were selected. Dietary weight loss program resulted in a pooled mean BMI reduction of 4.8 kg/m(2) (95 % confidence interval [CI] 3.8-5.9). The random-effects pooled apnea hypopnea (AHI) indices at pre- and post-dietary intervention were 52.5 (range 10.0-91.0) and 28.3 events/h (range 5.4-64.5), respectively (p < 0.001). Compared to control, the weighted mean difference of AHI was decreased by -14.3 events/h (95 % CI -23.5 to -5.1; p = 0.002) in favor of the dietary weight loss programs.

CONCLUSIONS

Dietary weight loss programs are effective in reducing the severity of OSA but not adequate in relieving all respiratory events. Weight reduction programs should be considered as adjunct rather than curative therapy.

Obstructive sleep apnea and bone mineral density in obese patients

CONTEXT

Obesity and its co-morbidities may adversely affect bone mineral density (BMD). Obstructive sleep apnea (OSA) is a major complication of obesity. To date, the effects of OSA on BMD in obese patients have been poorly studied.

OBJECTIVE

To examine whether the severity of OSA independently correlates with BMD in obese patients.

METHODS

One hundred and fifteen obese subjects with OSA (Apnea/Hypopnea Index [AHI] ≥5 events per hour) were included in the study. BMD was measured at lumbar spine, total hip, and femoral neck by dual energy X-ray absorptiometry. Body mass index, lean mass, and representative measures of metabolic syndrome (waist circumference, fasting plasma glucose, blood pressure, HDL-cholesterol, triglycerides) and inflammation (ESR, CRP, fibrinogen) were also evaluated.

RESULTS

BMD did not differ among obese individuals regardless of OSA severity. Correlation coefficient analysis for all the covariates showed a lack of association between AHI and BMD that was strongly influenced by age and weight.

CONCLUSION

Our study does not support an independent association between AHI and BMD in obese patients. Controlled studies involving a greater number of patients are warranted.