Adipocytokines in sleep apnea syndrome

The Modulation of Adipokines, Adipomyokines, and Sleep Disorders on Carcinogenesis

Obesity and sarcopenia, i.e., decreased skeletal muscle mass and function, are global health challenges. Moreover, people with obesity and sedentary lifestyles often have sleep disorders. Despite the potential associations, metabolic disturbances linking obesity, sarcopenia, and sleep disorders with cancer are neither well-defined nor understood fully. Abnormal levels of adipokines and adipomyokines originating from both adipose tissue and skeletal muscles are observed in some patients with obesity, sarcopenia and sleep disorders, as well as in cancer patients. This warrants investigation with respect to carcinogenesis. Adipokines and adipomyokines may exert either pro-carcinogenic or anti-carcinogenic effects. These factors, acting independently or together, may significantly modulate the incidence and progression of cancer. This review indicates that one of the possible pathways influencing the development of cancer may be the mutual relationship between obesity and/or sarcopenia, sleep quantity and quality, and adipokines/adipomyokines excretion. Taking into account the high proportion of persons with obesity and sedentary lifestyles, as well as the associations of these conditions with sleep disturbances, more attention should be paid to the individual and combined effects on cancer pathophysiology.

Adipocytokines in obstructive sleep apnea: A systematic review and meta-analysis

BACKGROUND AND AIM

Adipocytokines play an important role in obstructive sleep apnea (OSA) by mediating inflammatory responses. Previous studies have reported that OSA is related to a change in the serum levels of adipocytokines; however, the results are still controversial. This meta-analysis aimed to assess the relationship between OSA and circulating level of adipocytokines in adults and children.

METHODS

A comprehensive search was conducted in databases of Medline/PubMed and Scopus for pertinent articles published since their inception to July 2022. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) were used to assess the strength of the relationship between the concentrations of adipocytokines with OSA.

RESULTS

In the overall analysis, contrary to IL-10, which showed a significant reduction, IL-1β, IL-4, IL-8, IL-17, and IFN- gamma showed higher levels in OSA patients in comparison with control groups (p <0.05). For adults, IL-1β, IL-8, IL-17, IL-18, vaspin, visfatin, and chemerin were linked to a greater serum levels in patients with OSA, while, IL-5 and IL-10 were detected significantly lower in adults with OSA in comparison with healthy adults (p <0.05). In children with OSA, the serum levels of IL-4, IL-8, IL-12, IL-17, IL-23, and IFN-gamma were significantly higher than healthy children (p <0.05).

CONCLUSION

The levels of inflammatory markers were found to be higher in OSA patients compared with control individuals, suggesting that adipocytokines may contribute to the pathology of OSA.

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.

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.

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.

Effect of OSA on hypoxic and inflammatory markers during CPAP withdrawal: Further evidence from three randomized control trials

BACKGROUND AND OBJECTIVE

Obstructive sleep apnoea (OSA) is associated with cardiovascular disease. Intermittent hypoxia, endothelial dysfunction and adipose tissue-mediated inflammation have all been linked to cardiovascular disease in OSA. We therefore explored the effect of OSA on relevant associated blood markers: adrenomedullin (ADM), endocan, endothelin-1 (ET-1), resistin and vascular endothelial growth factor (VEGF).

METHODS

Patients with OSA, established on and compliant with continuous positive airways pressure (CPAP) therapy for >1 year were included from three randomized controlled trials, conducted at two centres. Patients were randomized to either continued therapeutic CPAP or sham CPAP (CPAP withdrawal) for 2 weeks. Blood markers were measured at baseline and at 14 days and the treatment effect between sham CPAP and therapeutic CPAP was analysed.

RESULTS

A total of 109 patients were studied (therapeutic CPAP n = 54, sham CPAP n = 55). Sham CPAP was associated with a return of OSA (between-group difference in oxygen desaturation index (ODI) 36.0/h, 95% CI 29.9-42.2, P < 0.001). Sham CPAP was associated with a reduction in ADM levels at 14 days (-26.0 pg/mL, 95% CI -47.8 to -4.3, P = 0.02), compared to therapeutic CPAP. Return of OSA was not associated with changes in endocan, ET-1, resistin or VEGF.

CONCLUSION

Whilst CPAP withdrawal was associated with return of OSA, it was associated with an unexpected significant reduction in the vasodilator ADM and not with expected increases in hypoxia-induced markers, markers of endothelial function or resistin. We propose that the vascular effects occurring in OSA may be brought about by other mechanisms, perhaps partly through a reduction in ADM.

8-isoprostanes and resistin as markers of vascular damage in non-hypersomnolent obstructive sleep apnoea patients

BACKGROUND

Oxidative stress and inflammation are assumed as the main pathological triggers for vascular damage in hypersomnolent obstructive sleep apnoea (OSA) patients, whereas their exact role in less symptomatic population is currently unknown.

AIM

To determine whether oxidative stress (urinary 8-isoprostane concentration) and inflammation (plasma resistin levels) are associated with vascular damage in non-hypersomnolent (Epworth Sleep Score <11) OSA patients.

METHODS

A total of 325 consecutive patients have undergone standard polysomnography, and 256 of them were diagnosed with OSA. Excessive daytime sleepiness was assessed by the Epworth Sleepiness Scale (ESS). Only 86 patients with ESS <11 participated in the study. The control group was presented by 45 subjects without OSA. Endothelial function was assessed by ultrasonographic measurement of flow-mediated dilatation (FMD). Intima-media thickness (IMT) and ankle-brachial index (ABI) were determined by ultrasonography. Urinary 8-isoprostanes (Cayman Chemical, USA) were measured, applying mass spectrometry. Resistin (RayBio_ Human ResistinCat#:ELH-Resistin-001) plasma levels were detected by ELISA.

RESULTS

In patients with OSA, flow-mediated dilatation was significantly lower than in control subjects (4·62% ±1·9) and (7·1% ±2·8), respectively (P: 0·013). The prevalence of plaques in a.carotis communis was higher in OSA (16% versus 4%). The same is observed regarding a.tibialis posterior (81% vs. 29%). The average IMT and ABI in OSA and in the control group were, respectively, (IMT - 800 µm versus. 666 µm); (ABI -1·06 versus 1·20). Urinary isoprostanes were higher in OSA patients (0·091 versus 0·078) and correlated negatively to FMD (r: -0·825, P: 0·00), IMT (r: -0·324, P: 0·003) and ABI (r: -0·226, P: 0·043). No association between resistin and the degree of vascular injury was found.

CONCLUSIONS

In comparison with the control group, increased prevalence of endothelial dysfunction and vascular damage was established in OSA patients without excessive daytime sleepiness. Urinary 8-isoprostanes (oxidative stress markers) are closely associated with FMD (endothelial dysfunction), IMT and ABI (vascular damage). Resistin plasma levels correlated neither to FMD, nor to IMT or ABI.

Resistin - the link between adipose tissue dysfunction and insulin resistance in patients with obstructive sleep apnea

Background

Resistin is an adipocytokine, associated with obesity and inflammation. Its exact role in insulin resistance and diabetes in the general population is still controversial. The relation between resistin plasma levels, insulin resistance and risk of impaired glucose metabolism in OSA patients has not been investigated.

Materials and methods

Plasma levels of resistin were measured in 67 patients with OSA and impaired glucose metabolism. 34,7% (23/67) had diabetes; 40% (27/67) patients had impаired glucose tolerance(IGT); 25,3%(17/67) had normal glucose metabolism (NGM). The association between resistin, BMI, obesity, markers of insulin resistance, oxidative stress and sleep study characteristics was analysed. The different groups of patients were compared in regards to glucometabolic parameters and biomarkers of oxidative stress – isoprostanes and insulin resistance – free fatty acids (FFA).

Results

Plasma levels of resistin were higher in patients with diabetes (6,12 ±5,93ng/ml), compared to those with IGT (3,85±2,81ng/ml, p-0,021) and NGM (3,77±3,23, p-0,043). Resistin did not differ between patients with IGT and NGM (p-0,954). In OSA patients with BMI>40 resistin plasma levels correlated neither to the clinical parameters (BMI, IRI, HOMA-I, HbA1C, AHI, desaturation index), nor to the biomarkers of oxidative stress and insulin resistance. Free fatty acids (0,232>0,177mmol/l, p-0,037) were higher in diabetics in comparison to NGM.

Conclusions

Plasma resistin levels in OSA patients with BMI>40 are independent of insulin resistance and are not associated with the parameters, characterising the oxidative stress or severity of OSA. Resistin could be used in a multiple panel of clinical and biomarkers to discern patients with diabetes from those with IGT; in OSA patients with BMI >40 resistin together with HbA1C could discern patients with diabetes from those with NGM. In OSA patients with BMI >40 FFA and HbA1C are useful clinical markers in assessing the risk of dysglycaemia among patients with normal and IGT.

The effect of sleep apnea syndrome on the development of diabetic nephropathy in patients with type 2 diabetes

AIMS

Type 2 diabetes mellitus and obstructive sleep apnea syndrome (OSAS) are serious comorbidities. Effects of OSAS on diabetic microvascular complications are ongoing research subjects. We evaluated the incidence of OSAS in Type 2 diabetes mellitus patients with nephropathy and with no renal involvement.

METHODS

A total of 52 people with diabetes were enrolled in this study. Patients body mass indices were calculated and fasting glucose, glycosylated hemoglobin, urea, creatinine, total lipid profile, and urinary albumin excretion were evaluated. Full polysomnography was used to detect sleep disorders.

RESULTS

Baseline characteristics and laboratory results of the patients were similar. Meeting criteria for OSAS was detected in 35 of the 54 patients (67.3%). 25 patients (48%) had mild, six patients (11.5%) had moderate, and four patients (7.7%) had severe sleep disorders. There was no significant relationship between respiratory obstructive parameters and microalbuminuria (R=0.91, p=0.362). Substantial correlation was detected between lower values of serum triglyceride levels and lower respiratory indices (R=0.299, p=0.031).

CONCLUSIONS

In type 2 diabetes accompanying OSAS affects glucose regulation but its effect on nephropathy development is currently a subject of research.

Type 2 diabetes and pre-diabetes are associated with obstructive sleep apnea in extremely obese subjects: a cross-sectional study

Background

Obstructive sleep apnea (OSA) is a common yet underdiagnosed condition. The aim of our study is to test whether prediabetes and type 2 diabetes are associated with obstructive sleep apnea (OSA) in extremely obese (BMI ≥ 40 kg/m²) subjects.

Methods

One hundred and thirty seven consecutive extremely obese patients (99 females) from a controlled clinical trial [MOBIL-study (Morbid Obesity treatment, Bariatric surgery versus Intensive Lifestyle intervention Study) (ClinicalTrials.gov number NCT00273104)] underwent somnography with Embletta^® and a 2-hour oral glucose tolerance test (OGTT). OSA was defined by an apnea-hypopnea index (AHI) ≥ 5 events/hour. Patients were categorized into three groups according to criteria from the American Diabetes Association: normal glucose tolerance, pre-diabetes and type 2 diabetes. Multiple logistic regression analysis was used to identify possible determinants of OSA.

Results

The patients had a mean (SD) age of 43 (11) years and a body mass index (BMI) of 46.9 (5.7) kg/m². Males had significantly higher AHI than females, 29 (25) vs 12 (17) events/hour, p < 0.001. OSA was observed in 81% of men and in 55% of women, p = 0.008. Twenty-nine percent of subjects had normal glucose tolerance, 42% had pre-diabetes and 29% had type 2 diabetes. Among the patients with normal glucose tolerance 33% had OSA, while 67% of the pre-diabetic patients and 78% of the type 2 diabetic patients had OSA, p < 0.001. After adjusting for age, gender, BMI, high sensitive CRP and HOMA-IR, both pre-diabetes and type 2 diabetes were still associated with OSA, odds ratios 3.18 (95% CI 1.00, 10.07), p = 0.049 and 4.17 (1.09, 15.88), p = 0.036, respectively. Mean serum leptin was significantly lower in the OSA than in the non-OSA group, while other measures of inflammation did not differ significantly between groups.

Conclusions

Type 2 diabetes and pre-diabetes are associated with OSA in extremely obese subjects.

Trial registration

MOBIL-study (Morbid Obesity treatment, Bariatric surgery versus Intensive Lifestyle intervention Study) (ClinicalTrials.gov number NCT00273104)