Reduced levels of adiponectin in sleep apnea syndrome

Evaluation of Plasma/Serum Adiponectin (an Anti-Inflammatory Factor) Levels in Adult Patients with Obstructive Sleep Apnea Syndrome: A Systematic Review and Meta-Analysis

Background and objective: A variety of diseases, including obesity, type ‖ diabetes, and cardiovascular diseases are associated with obstructive sleep apnea syndrome (OSAS), and decreased adiponectin levels have been shown to be associated with an increased risk of these diseases. However, the association of blood levels of adiponectin in OSAS patients is a challenging and unknown issue with conflicting results. Therefore, we performed a systematic review and a meta-analysis to evaluate plasma/serum adiponectin levels in adult patients with OSAS. Materials and methods: A comprehensive search in four databases (PubMed/Medline, Web of Science, Scopus, and Cochrane Library) was performed in literature dated older than 12 March 2022, to retrieve the relevant articles. Effect sizes were calculated to show the standardized mean difference (SMD) along with a 95% confidence interval (CI) of plasma/serum of adiponectin between the OSAS patients and controls. The software RevMan 5.3, NCSS 21.0.2, CMA 2.0, trial sequential analysis (TSA) 0.9.5.10 beta, and GetData Graph Digitizer 2.26 were used for data synthesis in the meta-analysis. Results: A total of 28 articles including 36 studies were entered into the meta-analysis. The results showed that pooled SMD was −0.71 (95% CI: −0.92, 0.50; p < 0.00001; I2 = 79%) for plasma/serum levels of adiponectin in OSAS cases compared to the controls. The subgroup analyses showed that the geographical region and the Apnea-Hypopnea-Index (AHI) could be confounding factors in the pooled analysis of plasma/serum adiponectin levels. The sensitivity analysis showed the stability of the results. The radial and L’Abbé plots confirmed evidence of heterogeneity. Trial sequential analysis showed sufficient cases in the meta-analysis. Conclusions: With sufficient cases and stable results, the main finding of the meta-analysis identified significantly reduced plasma/serum levels of adiponectin in OSAS cases compared with the controls. This result suggests a potential role of adiponectin in the pathogenesis of OSAS.

Associations of short sleep duration with appetite-regulating hormones and adipokines: A systematic review and meta-analysis

In the current study, a systematic review and meta-analysis were conducted to summarize and assess whether short sleep duration is associated with appetite-regulating hormones and adipokine levels. Reference databases were searched for studies related to sleep and appetite-regulating hormones and adipokines. Qualitative and quantitative syntheses were conducted to evaluate the relationship between sleep duration and the level of appetite-regulating hormones and adipokines, including leptin, ghrelin, adiponectin, resistin, and orexin. Twenty-one of 3536 studies, covering a total of 2250 participants, met the inclusion criteria. Leptin, ghrelin, and adiponectin were included in the meta-analysis. Ghrelin levels were higher in the short sleep group (standard mean difference [SMD] = 0.14, 95% CI [0.03, 0.25], p = 0.01). Significant differences between the short sleep group and recommended sleep group were also noted in leptin level experimental subgroup studies (SMD = 0.19, 95% CI [0.03, 0.35], p = 0.02) and ghrelin level cross-sectional subgroup studies (SMD = 0.14, 95% CI [0.02, 0.27], p = 0.03). A rise in leptin and ghrelin levels were also observed in sleep deprivation groups (SMD = 0.24, 95% CI [0.10, 0.39], p = 0.001 and SMD = 0.18, 95% CI [0.04, 0.33], p = 0.01, respectively). In conclusion, short sleep duration is associated with an increased ghrelin level, while sleep deprivation had a significant effect on the levels of both leptin and ghrelin.

Alterations in Serum Adropin, Adiponectin, and Proinflammatory Cytokine Levels in OSAS

Objective

The present study was planned to examine the relationships between obstructive sleep apnea syndrome (OSAS) and the newly revealed adipokines adropin and adiponectin concentrations that display significant metabolic and cardiovascular functions and the levels of proinflammatory cytokine levels.

Method

A total of 166 overweight and obese male patients with a body mass index (BMI) >27 kg/m² were included in the study. Among study participants, 84 were recently diagnosed with OSAS by polysomnography with an apnea-hypopnea index (AHI) ≥5, and 82 were nonapneic with normal polysomnography (AHI<5) findings. The serum adropin and adiponectin levels of all cases were analyzed via the enzyme-linked immunosorbent assay method. Serum interleukin-1 (IL-1) beta and tumor necrotizing factor-alpha (TNF-alpha) levels were determined using Luminex cytokine multiplex analyses.

Results

The mean age of the OSAS patients was 50.9 ± 5.7 years and BMI was 32.4 ± 6.0 kg/m², and there was no statistically significant difference determined with the control group (49.3 ± 5.8 years and 30.6 ± 5, 6 kg/m²) (p > 0.05). There were no statistically significant differences between the OSAS and control groups concerning total cholesterol, triglyceride, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and glucose levels. Adiponectin was lower in the OSAS group at a statistically significant level in comparison with the control group and was related at a statistically significant level to OSAS intensity. Adropin concentration was determined to be higher in the OSAS group at a statistically significant level in comparison with the control group.

Conclusion

The results of our study suggest that increased adropin concentration may be an indicator of endothelium dysfunction in OSAS patients. Serum adropin and adiponectin levels may be new bioindicators used for diagnosis and risk assessment in OSAS patients.

Association of serum adiponectin level with cystatin C in male patients with obstructive sleep apnea syndrome

PURPOSE

Obstructive sleep apnea syndrome (OSAS) was suggested to exert an effect on renal function. However, the specific mechanism was still unknown. We try to find the association among OSAS, adiponectin, and cystatin C and the effect of adiponectin on renal function in OSAS patients.

METHODS

Seventeen healthy men and seventy-three men which only had OSAS were included in the end. Apnea-hypopnea index (AHI), oxygen desaturation index (ODI), the percentage of total sleep time spent with SpO₂ < 90% (T90%), lowest O₂ saturation (LaSO₂), Epworth Sleepiness Scale (ESS) score, serum adiponectin, and high-sensitive C-reactive protein (hsCRP) were detected in all subjects, and renal function was evaluated with creatinine, cystatin C, and estimated glomerular filtration rate (eGFR).

RESULTS

Demographic data, creatinine, and eGFR did not differ among the studied groups. Decreased serum adiponectin levels were associated with severe OSAS. OSAS patients had a higher hsCRP and cystatin C than those without OSAS. Serum adiponectin levels had a negative association with cystatin C. After adjusted for confounders, adiponectin, hsCRP, and ODI had a significant prediction on the cystatin C (β = - 0.218, p = 0.011; β = 0.226, p = 0.037; and β = 0.231, p = 0.029).

CONCLUSIONS

Decreased serum adiponectin was associated with increased cystatin C in male OSAS patients. These results suggest that serum adiponectin might be a regulatory factor for renal function in OSAS.

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.

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.

Association of adiponectin level and obstructive sleep apnea prevalence in obese subjects

Obstructive sleep apnea (OSA) is prevalent in obese subjects. Plasma adiponectin level in obese subjects is decreased. Whether reduced adiponectin level is associated with OSA is unknown. Participants without a previous diagnosis of OSA or who have not been treated with continuous positive airway pressure were enrolled and parameters of interest were collected. Polysomnography was performed to evaluate the presence of OSA and the severity of OSA as indexed by the apnea-hypopnea index (AHI). Between-group differences were analyzed. Pearson correlation analysis was used to evaluate the association between body mass index (BMI) with plasma levels of adiponectin and C-reactive protein (CRP) and AHI; and the association between plasma adiponectin level with CRP and AHI was also evaluated. Logistic regression analysis was conducted to evaluate the association between per 1-SD standardized decrease of plasma adiponectin level and the prevalence of OSA using stepwise adjustment models. A total of 486 participants were enrolled and the mean BMI was 26.9 ± 6.2 kg/m with obesity prevalence of 28%; and the mean AHI was 12.6 ± 8.9 per sleep hour with OSA prevalence of 42%. The mean adiponectin level was 18.4 ± 10.6 μg/mL. Compared with the nonobese group, participants in the obese group had higher BMI, neck girth, waist circumference, and AHI (P < .05 for all comparisons). The prevalence of OSA (51% vs 37%) and the proportion of moderate OSA (49% vs 42%) were also significantly higher, while adiponectin level (14.6 ± 8.7 μg/mL vs 20.7 ± 10.5 μg/mL) was significantly lower. In the obese group, plasma adiponectin level was decreased gradually with the increasing severity of OSA, which was not observed in the nonobese group. BMI was negatively correlated with adiponectin while positively correlated with CRP and AHI; and adiponectin was negatively correlated with both CRP and AHI. After adjusted for covariates including BMI and waist circumference, adiponectin remained significantly associated with OSA prevalence with odds ratio of 1.20 (95% confidence interval 1.12-1.65). In summary, our preliminary study suggests that in obese subjects, plasma adiponectin level is associated with the prevalence of OSA.

Effect of Continuous Positive Airway Pressure on Adiponectin in Patients with Obstructive Sleep Apnea: A Meta-Analysis

Objective

Obstructive sleep apnea (OSA) has been suggested to be associated with low levels of adiponectin. Continuous positive airway pressure (CPAP) is the gold standard treatment for OSA; however, previous studies assessing the effect of CPAP on adiponectin in patients with OSA yielded conflicting results. The present meta-analysis was performed to determine whether CPAP therapy could increase adiponectin levels.

Methods

Two reviewers independently searched PubMed, Cochrane library, Embase and Web of Science before February 2015. Information on characteristics of subjects, study design and pre- and post-CPAP treatment of serum adiponectin was extracted for analysis. Standardized mean difference (SMD) was used to analyze the summary estimates for CPAP therapy.

Results

Eleven studies involving 240 patients were included in this meta-analysis, including ten observational studies and one randomized controlled study. The meta-analysis showed that there was no change of adiponectin levels before and after CPAP treatment in OSA patients (SMD = 0.059, 95% confidence interval (CI) = −0.250 to 0.368, z = 0.37, p = 0.710). Subgroup analyses indicated that the results were not affected by age, baseline body mass index, severity of OSA, CPAP therapy duration, sample size and racial differences.

Conclusions

This meta-analysis suggested that CPAP therapy has no impact on adiponectin in OSA patients, without significant changes in body weight. Further large-scale, well-designed long-term interventional investigations are needed to clarify this issue.

Meta-analyses of the Association of Sleep Apnea with Insulin Resistance, and the Effects of CPAP on HOMA-IR, Adiponectin, and Visceral Adipose Fat

OBJECTIVE

We sought to conduct an updated meta-analysis of randomized controlled trials (RCTs) on the effect of continuous positive airway pressure (CPAP) on insulin resistance, as measured by homeostasis model assessment of insulin resistance (HOMA-IR), visceral abdominal fat (VAF), and adiponectin. Additionally, we performed a separate meta-analysis and meta-regression of studies on the association of insulin resistance and obstructive sleep apnea (OSA).

METHODS

All included studies were searched from PubMed (from conception to March 15, 2014). Data were pooled across all included RCTs as the mean difference in HOMA-IR and VAF, and as the standardized mean difference in the case of adiponectin analysis. From the included case-control studies, data on the difference of HOMA-IR between cases and controls were pooled across all studies, as the standardized mean difference (SMD).

RESULTS

There was a significant difference in HOMA-IR (-0.43 [95% CIs: -0.75 to -0.11], p = 0.008) between CPAP treated and non CPAP treated participants. However, there was no significant difference in VAF or adiponectin; (-47.93 [95% CI: -112.58 to 16.72], p = 0.14) and (-0.06 [95% CI: -0.28 to 0.15], p = 0.56), respectively. Meta-analysis of 16 case-control studies showed a pooled SMD in HOMA-IR of 0.51 (95% CI: 0.28 to 0.75), p ≤ 0.001, between cases and controls.

CONCLUSIONS

The results of our meta-analyses show that CPAP has a favorable effect on insulin resistance. This effect is not associated with any significant changes in total adiponectin levels or amount of VAF. Our findings also confirm a significant association between OSA and insulin resistance.

Obstructive sleep apnoea, insulin resistance and adipocytokines

Obstructive sleep apnoea (OSA) is associated with multiple cardiometabolic abnormalities. Obesity is considered a major risk factor for the development of OSA, and it is also an established risk factor for insulin resistance and other cardiometabolic disorders. The enigma remains whether OSA has any causal role in the adverse metabolic profile, independent of or beyond that due to obesity. Sleep apnoeas and hypopnoeas result directly in intermittent hypoxaemia and cerebral arousals, both of which may evoke a cascade of downstream biologic responses in various body tissues and cells. Adipose tissue is a major source of adipocytokines many of which play important roles in the regulation of various metabolic functions. It is hypothesized that OSA may, through its unique pathophysiology, affect metabolic function through modulation of production or action of adipocytokines. This review focuses on insulin resistance, glucose metabolism and relevant adipocytokines in the context of OSA.

Abnormal cytokine profile in patients with obstructive sleep apnea-hypopnea syndrome and erectile dysfunction

Patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) show a high prevalence of erectile dysfunction (ED). Although the underlying pathogenesis is still unknown, endothelial dysfunction, induced by inflammatory cytokines, chemokines, and adhesion molecules, has been proposed as a possible mechanism. The aim of this study was to assess whether OSAHS is associated with activation of the inflammatory cytokine system in patients with ED compared to the matched OSAHS patients with normal sexual function. Thirty-one patients with severe OSAHS and ED were included. Fifteen patients with severe OSAHS and without ED served as controls. Serum concentrations of high-sensitivity C-reactive protein (hsCRP), tumor necrosis factor-α (TNF-a), interleukin-6 (IL-6), interleukin-8 (IL-8), and adiponectin were measured after the diagnostic polysomnography. We found that hsCRP levels were significantly elevated in OSAHS patients with ED compared to controls. Similarly, TNF-a levels, IL-6, and IL-8 were elevated in OSAHS patients with ED compared to controls. Serum adiponectin levels were lower in OSAHS-ED patients, but the difference did not reach statistical significance. The presence of ED in patients with severe OSAHS is associated with elevated levels of inflammatory markers, underlining a possible involvement of endothelial dysfunction in the pathogenesis of ED.

Treating obstructive sleep apnea with continuous positive airway pressure benefits type 2 diabetes management

Type 2 diabetes mellitus (T2DM) and obstructive sleep apnea (OSA) are both common major public health concerns. Epidemiological and clinical evidence postulates that OSA may be a causal factor in the pathogenesis of T2DM. This review examines recent empirical developments in theory, research, and practice regarding T2DM and OSA. We first examined the data from 10 studies that covered 281 patients with T2DM who used continuous positive airway pressure therapy, followed by research that describes how hypoxia/reoxygenation in OSA may be key triggers that initiate or contribute to the status of insulin resistance and inflammation. We then propose mechanisms that may relate diabetes with OSA. The issues that should be addressed in the future are outlined. We suggest that intervention with continuous positive airway pressure may improve diabetic symptoms and should be encouraged for patients with diabetes.

Pathophysiologic mechanisms of cardiovascular disease in obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is a highly prevalent sleep disorder, characterized by repeated disruptions of breathing during sleep. This disease has many potential consequences including excessive daytime sleepiness, neurocognitive deterioration, endocrinologic and metabolic effects, and decreased quality of life. Patients with OSAS experience repetitive episodes of hypoxia and reoxygenation during transient cessation of breathing that provoke systemic effects. Furthermore, there may be increased levels of biomarkers linked to endocrine-metabolic and cardiovascular alterations. Epidemiological studies have identified OSAS as an independent comorbid factor in cardiovascular and cerebrovascular diseases, and physiopathological links may exist with onset and progression of heart failure. In addition, OSAS is associated with other disorders and comorbidities which worsen cardiovascular consequences, such as obesity, diabetes, and metabolic syndrome. Metabolic syndrome is an emerging public health problem that represents a constellation of cardiovascular risk factors. Both OSAS and metabolic syndrome may exert negative synergistic effects on the cardiovascular system through multiple mechanisms (e.g., hypoxemia, sleep disruption, activation of the sympathetic nervous system, and inflammatory activation). It has been found that CPAP therapy for OSAS provides an objective improvement in symptoms and cardiac function, decreases cardiovascular risk, improves insulin sensitivity, and normalises biomarkers. OSAS contributes to the pathogenesis of cardiovascular disease independently and by interaction with comorbidities. The present review focuses on indirect and direct evidence regarding mechanisms implicated in cardiovascular disease among OSAS patients.

Decreased levels of serum omentin-1 in patients with obstructive sleep apnoea syndrome

Background

Inflammation is involved in the mechanism of obstructive sleep apnoea syndrome (OSAS). Omentin, a newly discovered adipokine, is implicated to play an anti-inflammatory role. This study aims to determine whether serum levels of omentin-1 are associated with the presence and severity of OSAS.

Methods

This study consisted of 192 patients with OSAS and 144 healthy subjects. Serum levels of omentin-1 were measured using enzyme-linked immunosorbent assay.

Results

Serum omentin-1 levels were significantly decreased in OSAS patients compared with healthy controls. Multivariable logistic regression analysis revealed that serum omentin-1 levels were inversely associated with the presence of OSAS (odds ratio 0.520, 95% confidence interval 0.433 to 0.623; P < 0.001). Severe OSAS patients had significantly lower serum omentin-1 levels compared with mild and moderate OSAS patients. Spearman correlation analysis showed that serum omentin-1 levels were correlated with the severity of OSAS. Simple linear regression analysis showed that the serum levels of omentin-1 were negatively correlated with waist circumference, body mass index, systolic blood pressure, homeostasis model assessment of insulin resistance (HOMA-IR), C-reactive protein (CRP), and apnoea-hypopnoea index in patients with OSAS. Furthermore, only HOMA-IR and CRP remained inversely associated with serum omentin-1 after multiple stepwise regression analysis.

Conclusion

Decreased serum omentin-1 levels could be considered as an independent predictive marker of the presence and severity of OSAS.

Obstructive sleep apnoea and type 2 diabetes mellitus: a bidirectional association

Obstructive sleep apnoea and type 2 diabetes are common medical disorders that have important clinical, epidemiological, and public health implications. Research done in the past two decades indicates that obstructive sleep apnoea, through the effects of intermittent hypoxaemia and sleep fragmentation, could contribute independently to the development of insulin resistance, glucose intolerance, and type 2 diabetes. Conversely, type 2 diabetes might increase predisposition to, or accelerate progression of, obstructive and central sleep apnoea, possibly through the development of peripheral neuropathy and abnormalities of ventilatory and upper airway neural control. Although more research is needed to clarify the mechanisms underlying the bidirectional association between the two disorders, their frequent coexistence should prompt all health-care professionals to embrace clinical practices that include screening of a patient presenting with one disorder for the other. Early identification of obstructive sleep apnoea in patients with metabolic dysfunction, including type 2 diabetes, and assessment for metabolic abnormalities in those with obstructive sleep apnoea could reduce cardiovascular disease risk and improve the quality of life of patients with these chronic diseases.

Insulin resistance and adipose-derived hormones in young men with untreated obstructive sleep apnea

PURPOSE

Obstructive sleep apnea (OSA) increases the risk for insulin resistance (IR). The mechanisms that link the two are not clear and are frequently confounded by obesity. OSA is associated with alterations in adipose-derived hormones (adipokines) that increase IR; however, previous studies have focused on middle-aged and older adults. The objective of this study was to determine if IR and alterations in adipokines exist in young men with OSA, independent of obesity.

METHODS

Subjects were assigned into the following groups based on body mass index and presence of OSA: obese with OSA (OSA, n = 12), obese without OSA (NOSA, n = 18), and normal weight without OSA (CON, n = 15). Fasting blood was obtained for batch analysis of biomarkers of IR. The homeostasis model assessment (HOMA) method was used to assess IR.

RESULTS

HOMA and leptin were higher in the OSA group than the CON group. There were no differences in insulin, tumor necrosis factor alpha (TNF-α), and interleukin-6 (IL-6) between the OSA and NOSA groups. Adiponectin was lower in the OSA group vs. NOSA and CON; however, when controlled for central abdominal fat (CAF), the difference was nullified. When controlled for total body adiposity, however, CAF was 24 % higher in the subjects with OSA vs. subjects without OSA.

CONCLUSIONS

These findings suggest that excess CAF in young men with OSA may contribute to risk for type 2 diabetes indirectly by a degree that would otherwise not be reached through obesity, although further research is needed.

The influence of obesity and obstructive sleep apnea on metabolic hormones

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is a common disorder characterized by excessive daytime sleepiness and repetitive upper airway obstruction episodes during sleep. Clinically, obesity is a major risk factor for developing OSAS. However, OSAS has been associated with hormonal and metabolic alterations that could predispose patients to obesity. The aim of this study was to investigate the independent role of apneas and obesity on plasma levels of metabolic hormones (adiponectin, ghrelin, and leptin) in patients with OSAS.

METHODS

We have studied patients with OSAS and controls with and without obesity. All patients were male, had an apnea-hypopnea index of 20/h or greater, and were eligible for nasal continuous positive airway pressure (nCPAP) treatment. Patients were considered obese (n = 28) when their BMI was higher than 30 kg/m(2) and non-obese (n = 21) when it was lower than 27 kg/m(2). Non-obese control subjects (n = 20) were non-snorers with a normal cardiorespiratory sleep study, while obese control subjects (n = 10) were recruited from those obese subjects who were visited in our sleep unit and for whom OSAS was excluded by full polysomnography. A single blood sample was obtained from an antecubital vein in all participants after the completion of the nocturnal sleep laboratory recording. Plasma leptin, adiponectin, and ghrelin levels were determined by radioimmunoassay.

RESULTS

The adiponectin, ghrelin, and leptin plasma levels were similar in both patients and controls. There were differences in leptin and adiponectin plasma levels between the obese and non-obese in both patient and control groups. In the case of ghrelin, differences between obese and non-obese subjects were only seen in patients. There were no significant differences in hormone levels between the obese controls and obese patients or between non-obese controls and non-obese patients. After 3 months of nCPAP treatment, adiponectin levels decreased significantly both in obese and non-obese patients, and leptin levels decreased in obese patients. Finally, nCPAP did not reduce ghrelin in either obese or non-obese patients.

CONCLUSIONS

The basal levels of leptin, adiponectin, and ghrelin were mostly associated with obesity. We found that sleep apnea was not a determinant factor in leptin, adiponectin, and ghrelin hormonal levels. Interestingly, nCPAP treatment diminishes leptin in obese OSA patients and adiponectin levels in obese and non-obese patients with OSAS.

Hypertension in obesity

Obesity and HTN are on the rise in the world. HTN seems to be the most common obesity-related health problem and visceral obesity seems to be the major culprit. Unfortunately, only 31% of hypertensives are treated to goal. This translates into an increased incidence of CVD and related morbidity and mortality. Several mechanisms have been postulated as the causes of obesity-related HTN. Activation of the RAAS, SNS, insulin resistance, leptin, adiponectin, dysfunctional fat, FFA, resistin, 11 Beta dehydrogenase, renal structural and hemodynamic changes, and OSA are some of the abnormalities in obesity-related HTN. Many of these factors are interrelated. Treatment of obesity should begin with weight loss via lifestyle modifications, medications, or bariatric surgery. According to the mechanisms of obesity-related HTN, it seems that drugs that blockade the RAAS and target the SNS should be ideal for treatment. There is not much evidence in the literature that one drug is better than another in controlling obesity-related HTN. There have only been a few studies specifically targeting the obese hypertensive patient, but recent trials that emphasize the importance of BP control have enrolled both overweight and obese subjects. Until we have further studies with more in-depth information about the mechanisms of obesity-related HTN and what the targeted treatment should be, the most important factor necessary to control the obesity-related HTN pandemic and its CVD and CKD consequences is to prevent and treat obesity and to treat HTN to goal.

Effects of chronic intermittent hypoxia on genioglossus in rats

OBJECTIVE

The objective of this study was to investigate the effects of chronic intermittent hypoxia (CIH) on genioglossal ultrastructure and mitochondrial function as well as the intervention role of adiponectin (Ad).

METHODS

Forty-two Wistar rats were randomly divided into three groups with 14 rats in each. Rats in group A were kept breathing normal air, while rats in both groups B and C received the same CIH environment (a 2-min cycle, 1 min on, 1 min off with a nadir O(2) at 4-5%, 8 h/day for successive 5 weeks). However, rats in group C was given regular intravenous Ad injection (10 μg per time, twice a week for successive 5 weeks). A simultaneous intravenous injection of saline (0.5 ml per time) was carried in groups A and B. At the end of experiment, the genioglossal ultrastructure, the serum adiponectin levels, the mitochondrial membrane potential (ΔΨ(m)), and activities of respiratory chain complexes I and IV in mitochondrion of genioglossal cells were compared among groups.

RESULTS

Serum Ad level was significantly lower in group B than that in group A (P < 0.01). In group B, there were genioglussal myofibril discontinuities, lysis of myofilament, edema of mitochondria, and disruption of cristae, vacuolus, and lysis of some mitochondria. These pathological changes were less significant in group C. The relative value of ΔΨ(m) was the lowest in group B but the highest in group A (P < 0.01), with group B in between. The concentrations of mitochondrial complexes I and IV in group B were the lowest but became higher and higher from group C to A, with a significant difference among groups (all P < 0.05).

CONCLUSION

CIH could lead to hypoadiponectinemia, impaired genioglossal ultrastructure, and mitochondrial dysfunction. These changes could be improved by supplement of Ad.

Catecholamines, adiponectin, and insulin resistance as measured by HOMA in children with obstructive sleep apnea

INTRODUCTION

Obstructive sleep apnea (OSA) has been implicated in the pathophysiology of metabolic syndrome. Its contribution to insulin resistance is complicated by obesity and puberty. We hypothesized that OSA is associated with worse insulin resistance and lower adiponectin after adjustment for obesity and puberty and that catecholamines might mediate these changes.

METHODS

Normal controls and children with suspected OSA were recruited and categorized as pubertal or prepubertal. Overnight polysomnography (PSG) was performed. Subjects were categorized as OSA for total apnea hypopnea index (Total-AHI) > or = 1.5 events/h. Fasting blood glucose, insulin, adiponectin, and 24-hour urinary catecholamines were obtained. Homeostatic model assessment of insulin resistance (HOMA) was calculated. The independent effects of OSA upon HOMA, adiponectin, and urinary catecholamines following adjustment for body mass index (BMI) were determined. RESULTS (median; min, max): Subjects (n = 98, 42F; 11 +/- 4 years, 37 prepubertal) were generally overweight (BMI-Z = 2.1; -3, 4.1) and had wide-ranging insulin sensitivities (HOMA = 2.7; 0.5, 27) and PSG parameters (Total-AHI = 1.6; 0, 185). The risks of elevated insulin (P = 0.04) and HOMA (P = 0.05) were higher in OSA vs non OSA obese pubertal children. Polysomnographic markers of OSA, including Total-AHI (P = 0.001, R2 = 0.32), were negatively associated with adiponectin in pubertal children. Total-AHI and oxygen desaturation were associated with higher urinary normetanephrine and norepinephrine.

CONCLUSIONS

In obese pubertal children, OSA was associated with worse insulin resistance. Worsening OSA was associated with lower adiponectin and increasing urinary catecholamines. Whether OSA directly lowers adiponectin and aggravates a predisposition to insulin resistance is unknown, but these preliminary findings highlight the importance of further studying pediatric OSA.

Obstructive sleep apnea causes oxidative damage to plasma lipids and proteins and decreases adiponectin levels

PUPOSE: Obstructive sleep apnea (OSA) is associated with various metabolic disorders, and oxidative stress was suggested to play an important role. In the present study, we aimed to investigate serum adiponectin and oxidative stress markers, especially protein carbonyls, and to evaluate the correlation between these parameters and lipid, insulin and fasting glucose concentrations in OSA patients and controls.

METHOD

Blood was drawn from healthy male volunteers following full-night polysomnographic evaluation. Subjects were classified as controls (n = 24), mild OSA group (n = 9) and moderate-severe OSA group (n = 17) according to their apnea-hypopnea indices (AHIs). Serum lipids, fasting glucose, adiponectin, malondialdehyde (MDA), protein carbonyl concentrations, and paraoxonase activities were measured in all subjects.

RESULTS

Results of this study indicated that serum adiponectin concentrations were significantly decreased and MDA and protein carbonyl concentrations were significantly elevated in OSA patients compared to the controls. Protein carbonyl and MDA concentrations were significantly and positively correlated with AHI, while a significant negative correlation was found between adiponectin concentrations and AHI. Adiponectin levels were negatively correlated with MDA levels.

CONCLUSION

Results of this study, which is the first human study investigating and describing serum protein carbonyl concentrations in OSA patients, reveal that OSA causes increments in oxidative damage and decreases adiponectin levels. The recurrent hypoxia-reoxygenation attacks in OSA patients may activate oxidative stress, elevating sympathetic activity and leading to low levels of adiponectin.

Continuous positive airway pressure therapy improves hypoadiponectinemia in severe obese men with obstructive sleep apnea without changes in insulin resistance

BACKGROUND

Obstructive sleep apnea (OSA) is associated with several conditions that could facilitate the onset of cardiovascular and metabolic dysfunctions. Continuous positive airway pressure (CPAP) therapy has been shown to improve cardiovascular morbidity and mortality related to OSA, but the mechanisms underlying this association are not fully understood.

OBJECTIVE

The aim of the present study was to evaluate whether sleep apnea contributes to insulin resistance and inflammatory marker alterations and to evaluate the benefits of nasal CPAP therapy in severe obese patients with OSA.

METHODS

Plasma inflammatory cytokines and the homeostasis model assessment of insulin resistance index (HOMA-IR, Insulin Sensitivity Index [ISI]) were measured in severe obese male with OSA (n = 16) and compared with body mass index (BMI)-matched male controls without OSA (n = 13). Seven patients with severe sleep apnea (apnea-hypopnea index >30 events/h) were reevaluated after 3 months of nasal CPAP therapy.

RESULTS

OSA patients had a significantly lower adiponectin levels than obese controls (8.7 +/- 1.18 ng/mL vs. 15.0 +/- 2.55 ng/mL, P = 0.025). HOMA-IR, ISI, tumor necrosis factor-alpha (TNF-alpha, C-reactive protein (CRP), and interleukin-6 (IL-6) levels were not different between groups. Although insulin resistance index and BMI values did not change after 3 months of nCPAP therapy, adiponectin levels increased (P = 0.036) and the levels of TNF-alpha tended to decrease (P = 0.065). Changes in adiponectin levels during nCPAP therapy were positively correlated with an improvement in minimum oxygen saturation (r = 0.773; P = 0.041) and negatively correlated with changes in TNF-alpha levels (r = -0.885; P = 0.008).

CONCLUSIONS

nCPAP therapy reverses hypoadiponectinemia levels present in obese men with OSA, probably through reductions in hypoxia and inflammation activity.

Adipokines in children with obstructive sleep apnea and the effects of treatment

BACKGROUND

The objective of this study was to evaluate circulating adipokines concentration in children with and without obstructive sleep apnea (OSA) and to determine the effects of treatment of OSA on their plasma concentration.

METHODS

Children with habitual snoring and symptoms suggestive of OSA were consecutively recruited. Their parents completed a sleep apnea symptom questionnaire, and the subjects underwent physical examination and an overnight polysomnography (PSG). OSA was diagnosed if they had an obstructive apnea index > 1. Fasting serum adiponectin, leptin, and lipid profiles were taken after overnight PSG. The subjects were divided into groups as obese, nonobese, and with and without OSA for comparison.

RESULTS

One hundred forty-one children, of whom 96 were boys, with a median (interquartile range) age of 10.8 (8.5-12.8) years were recruited. Forty-three subjects had OSA. Subjects with OSA did not have significantly different adiponectin and leptin concentrations than those without OSA for both the obese and nonobese groups. Stepwise multiple linear regressions revealed that systolic BP, age, high-density lipoprotein cholesterol, and BMI z-score were independently associated with adiponectin, whereas diastolic BP, triglyceride, height, and BMI z-score were independently associated with leptin concentration. Sixteen children with OSA underwent treatment, and there was reduction in their plasma adiponectin concentration after intervention, but such change became insignificant after controlling for change in the BMI z-score.

CONCLUSIONS

BMI rather than OSA was the main determinant of adipokines in children.

Obstructive sleep apnea, inflammation, and the metabolic syndrome

The combination of metabolic syndrome and obstructive sleep apnea (OSA) has been termed "syndrome Z." The prevalence of both OSA and metabolic syndrome is increasing worldwide, in part linked to the epidemic of obesity. Beyond their epidemiologic relationship, growing evidence suggests that OSA may be causally related to metabolic syndrome. We are only beginning to understand the potential mechanisms underlying the OSA-metabolic syndrome interaction. Although there is no clear consensus, there is growing evidence that alterations in the hypothalamic-pituitary axis, generation of reactive oxygen species (ROS) due to repetitive hypoxia, inflammation, and generation of adipokines may be implicated in the changes associated with both OSA and metabolic syndrome. Whether some or all of these metabolic alterations mechanistically link OSA to metabolic syndrome remains to be proven, but it is an area of intense scientific interest.

Obstructive sleep apnea, immuno-inflammation, and atherosclerosis

Obstructive sleep apnea (OSA) is a highly prevalent sleep disorder leading to cardiovascular and metabolic complications. OSA is also a multicomponent disorder, with intermittent hypoxia (IH) as the main trigger for the associated cardiovascular and metabolic alterations. Indeed, recurrent pharyngeal collapses during sleep lead to repetitive sequences of hypoxia-reoxygenation. This IH induces several consequences such as hemodynamic, hormonometabolic, oxidative, and immuno-inflammatory alterations that may interact and aggravate each other, resulting in artery changes, from adaptive to degenerative atherosclerotic remodeling. Atherosclerosis has been found in OSA patients free of other cardiovascular risk factors and is related to the severity of nocturnal hypoxia. Early stages of artery alteration, including functional and structural changes, have been evidenced in both OSA patients and rodents experimentally exposed to IH. Impaired vasoreactivity with endothelial dysfunction and/or increased vasoconstrictive responses due to sympathetic, endothelin, and renin-angiotensin systems have been reported and also contribute to vascular remodeling and inflammation. Oxidative stress, inflammation, and vascular remodeling can be directly triggered by IH, further aggravated by the OSA-associated hormonometabolic alterations, such as insulin resistance, dyslipidemia, and adipokine imbalance. As shown in OSA patients and in the animal model, genetic susceptibility, comorbidities (obesity), and life habits (high fat diet) may aggravate atherosclerosis development or progression. The intimate molecular mechanisms are still largely unknown, and their understanding may contribute to delineate new targets for prevention strategies and/or development of new treatment of OSA-related atherosclerosis, especially in patients at risk for cardiovascular disease.

Hypoadiponectinemia is related to sympathetic activation and severity of obstructive sleep apnea

STUDY OBJECTIVES

Hypoadiponectinemia is associated with cardiovascular morbidity and diabetes mellitus. We hypothesize that adiponectin may be downregulated in sleep apnea through various mechanisms, contributing to cardiometabolic risks. This study investigated the relationship between serum adiponectin and sleep disordered breathing and its potential determinants.

DESIGN

Cross-sectional study.

SUBJECTS AND SETTING

Adult men without prevailing medical comorbidity from the sleep clinic in a teaching hospital.

MEASUREMENTS & RESULTS

One hundred thirty-four men underwent polysomnography, with mean age of 43.9 (9.8) years, and median apnea-hypopnea index (AHI) of 17.1 (5.7, 46.6). Overnight urine samples for catecholamines and blood samples for analyses of insulin, glucose and adiponectin levels from fasting subjects were taken. Insulin resistance was estimated by homeostasis model assessment (HOMA-IR). Magnetic resonance imaging was performed to quantify the amount of abdominal visceral fat. Serum adiponectin level, adjusted for age, body mass index, and visceral fat volume, was significantly lower in subjects with severe obstructive sleep apnea (AHI > or =30) compared with those with an AHI of less than 30: 4.0 (3.1, 5.4) versus 5.4 (3.6, 7.9) microg/mL, P = 0.039. After we adjusted for adiposity, adiponectin levels remained negatively correlated with AHI (P = 0.037), arousal index (P = 0.022), HOMA-IR/fasting insulin (P < 0.001), and urinary norepinephrine and normetanephrine (P < 0.008). In a multiple stepwise regression model, the independent determinants of adiponectin after adjustment for adiposity were HOMA-IR (P < 0.001) and urinary norepinephrine and normetanephrine (P = 0.037).

CONCLUSIONS

Adiponectin was suppressed in subjects with severe obstructive sleep apnea, independent of obesity. Adiponectin levels were determined by insulin resistance and sympathetic activation, factors that may be totally or partially attributed to sleep disordered breathing.

The metabolic syndrome

The "metabolic syndrome" (MetS) is a clustering of components that reflect overnutrition, sedentary lifestyles, and resultant excess adiposity. The MetS includes the clustering of abdominal obesity, insulin resistance, dyslipidemia, and elevated blood pressure and is associated with other comorbidities including the prothrombotic state, proinflammatory state, nonalcoholic fatty liver disease, and reproductive disorders. Because the MetS is a cluster of different conditions, and not a single disease, the development of multiple concurrent definitions has resulted. The prevalence of the MetS is increasing to epidemic proportions not only in the United States and the remainder of the urbanized world but also in developing nations. Most studies show that the MetS is associated with an approximate doubling of cardiovascular disease risk and a 5-fold increased risk for incident type 2 diabetes mellitus. Although it is unclear whether there is a unifying pathophysiological mechanism resulting in the MetS, abdominal adiposity and insulin resistance appear to be central to the MetS and its individual components. Lifestyle modification and weight loss should, therefore, be at the core of treating or preventing the MetS and its components. In addition, there is a general consensus that other cardiac risk factors should be aggressively managed in individuals with the MetS. Finally, in 2008 the MetS is an evolving concept that continues to be data driven and evidence based with revisions forthcoming.

Obstructive sleep apnea syndrome is a systemic disease. Current evidence

Obstructive sleep apnea syndrome (OSAS) is a highly prevalent sleep disorder, characterized by repeated disruptions of breathing during sleep. This disease has many potential consequences including excessive daytime sleepiness, neurocognitive deterioration, endocrinologic and metabolic effects, and decreased quality of life. Metabolic syndrome is another highly prevalence emerging public health problem that represents a constellation of cardiovascular risk factors. Each single component of the cluster increases the cardiovascular risk, but the combination of factors is much more significant. It has been suggested that the presence of OSAS may increase the risk of developing some metabolic syndrome features. Moreover, OSAS patients are at an increased risk for vascular events, which represent the greatest morbidity and mortality of all associated complications. Although the etiology of OSAS is uncertain, intense local and systemic inflammation is present. A variety of phenomena are implicated in this disease such as modifications in the autonomic nervous system, hypoxemia-reoxygenation cycles, inflammation, and coagulation-fibrinolysis imbalance. OSAS patients also present increased levels of certain biomarkers linked to endocrine-metabolic and cardiovascular alterations among other systemic consequences. All of this indicates that, more than a local abnormality, OSAS should be considered a systemic disease.

Hypertension in obesity

Hypertension and obesity are major components of the cardiometabolic syndrome and are both on the rise worldwide, with enormous consequences on global health and the economy. The relationship between hypertension and obesity is multifaceted; the etiology is complex and it is not well elucidated. This article, reviews the current knowledge on obesity-related hypertension. Further understanding of the underlying mechanisms of this epidemic will be important in devising future treatment avenues.