Circulating Survivin Levels in Obstructive Sleep Apnoea

The link between the sphingolipid rheostat and obstructive sleep apnea

Chronic inflammation induced by hypoxia during sleep is an important mechanism of microvascular damage in OSA patients. In this study, we investigated the role of the sphingosine rheostat, which has diverse inflammatory effects. Thirty-seven healthy subjects and 31 patients with OSA were recruited. We collected data on demographics and comorbidities. Plasma sphingosine-1-phosphate and ceramide antibody concentrations were measured by ELISA. The results were compared between the OSA and control groups, and the correlations between these measurements and markers of disease severity and comorbidities were explored. Ceramide antibody levels were significantly elevated in OSA patients (892.17 ng/ml) vs. controls (209.55 ng/ml). S1P levels were also significantly higher in patients with OSA (1760.0 pg/ml) than in controls (290.35 pg/ml, p < 0.001). The ceramide antibody concentration showed correlations with BMI (ρ = 0.25, p = 0.04), CRP (ρ = 0.36, p = 0.005), AHI (ρ = 0.43, p < 0.001), ODI (ρ = 0.43, p < 0.001), TST90% (ρ = 0.35, p = 0.004) and the lowest oxygen saturation (ρ =  0.37, p = 0.001) in the whole study population but not when patients with OSA were analyzed separately. The elevated ceramide antibody and sphingosine-1-phosphate concentrations in patients suffering from OSA suggests their involvement in the pathomechanism of OSA and its comorbidities.

Role of epigenetic abnormalities and intervention in obstructive sleep apnea target organs

ABSTRACT

Obstructive sleep apnea (OSA) is a common condition that has considerable impacts on human health. Epigenetics has become a rapidly developing and exciting area in biology, and it is defined as heritable alterations in gene expression and has regulatory effects on disease progression. However, the published literature that is integrating both of them is not sufficient. The purpose of this article is to explore the relationship between OSA and epigenetics and to offer better diagnostic methods and treatment options. Epigenetic modifications mainly manifest as post-translational modifications in DNA and histone proteins and regulation of non-coding RNAs. Chronic intermittent hypoxia-mediated epigenetic alterations are involved in the progression of OSA and diverse multiorgan injuries, including cardiovascular disease, metabolic disorders, pulmonary hypertension, neural dysfunction, and even tumors. This article provides deeper insights into the disease mechanism of OSA and potential applications of targeted diagnosis, treatment, and prognosis in OSA complications.

Intermittent Hypoxia and Atherosclerosis: From Molecular Mechanisms to the Therapeutic Treatment

Intermittent hypoxia (IH) has a dual nature. On the one hand, chronic IH (CIH) is an important pathologic feature of obstructive sleep apnea (OSA) syndrome (OSAS), and many studies have confirmed that OSA-related CIH (OSA-CIH) has atherogenic effects involving complex and interacting mechanisms. Limited preventive and treatment methods are currently available for this condition. On the other hand, non-OSA-related IH has beneficial or detrimental effects on the body, depending on the degree, duration, and cyclic cycle of hypoxia. It includes two main states: intermittent hypoxia in a simulated plateau environment and intermittent hypoxia in a normobaric environment. In this paper, we compare the two types of IH and summarizes the pathologic mechanisms and research advances in the treatment of OSA-CIH-induced atherosclerosis (AS), to provide evidence for the systematic prevention and treatment of OSAS-related AS.

Current and future strategies for diagnostic and management of obstructive sleep apnea

INTRODUCTION

Obstructive sleep apnea (OSA) is a common sleep disorder with multiple comorbidities including hypertension, diabetes, and cardiovascular disorders. Detected based on an overnight sleep study is called polysomnography (PSG); OSA still remains undiagnosed in majority of the population mainly attributed to lack of awareness. To overcome the limitations posed by PSG such as patient discomfort and overnight hospitalization, newer technologies are being explored. In addition, challenges associated with current management of OSA using continuous positive airway pressure (CPAP), etc. presents several pitfalls.

AREAS COVERED

Conventional and modern detection/management techniques including PSG, CPAP, smart wearable/pillows, bio-motion sensors, etc., have both pros and cons. To fulfill the limitations in OSA diagnostics, there is an imperative need for new technology for screening of symptomatic and more importantly asymptomatic OSA patients to reduce the risk of several associated life-threatening comorbidities. In this line, molecular marker-based diagnostics have shown great promises.

EXPERT OPINION

A detailed overview is presented on the OSA management and diagnostic approaches and recent advances in the molecular screening methods. The potentials of biomarker-based detection and its limitations are also portrayed and a comparison between the standard, current modern approaches, and promising futuristic technologies for OSA diagnostics and management is set forth.ABBREVIATIONS AHI: Apnea hypopnea index; AI: artificial intelligence; CAM: Cell adhesion molecules; CPAP: Continuous Positive Airway Pressure; COVID-19: Coronavirus Disease 2019; CVD: Cardiovascular disease; ELISA: Enzyme linked immunosorbent assay; HSAT: Home sleep apnea testing; IR-UWB: Impulse radio-ultra wideband; MMA: maxillomandibular advancement; PSG: Polysomnography; OSA: Obstructive sleep apnea; SOD: Superoxide dismutase; QD: Quantum dot.

Evaluation of Blood Levels of C-Reactive Protein Marker in Obstructive Sleep Apnea: A Systematic Review, Meta-Analysis and Meta-Regression

(1) Introduction: High sensitivity C-reactive protein (hs-CRP) and CRP are inflammatory biomarkers associated with several inflammatory diseases. In both pediatric and adult individuals with Obstructive Sleep Apnea (OSA) higher hs-CRP and CRP were observed, compared to controls. With the present systematic review, meta-analysis and meta-regression we expand upon previous meta-analyses in four ways: (1) We included 109 studies (96 in adults and 13 in children); (2) we reported subgroup and meta-regression analyses in adults with OSA compared to controls on the serum and plasma levels of hs-CRP; (3) we reported subgroup and meta-regression analyses in adults with OSA compared to controls on the serum and plasma levels of CRP; (4) we reported serum and plasma levels of both hs-CRP and CRP in children with OSA, always compared to controls. (2) Materials and Methods: The PubMed/Medline, Scopus, Cochrane Library, and Web of Science databases were searched to retrieve articles published until 31 May 2020, with no restrictions. The data included basic information involving the first author, publication year, country of study, ethnicity of participants in each study, age, BMI, and AHI of both groups, and mean and standard deviation (SD) of plasma and serum levels of CRP and hs-CRP. (3) Results: A total of 1046 records were retrieved from the databases, and 109 studies were selected for the analysis (96 studies reporting the blood levels of hs-CRP/CRP in adults and 13 studies in children). For adults, 11 studies reported plasma hs-CRP, 44 serum hs-CRP, 9 plasma CRP, and 32 serum CRP levels. For children, 6 studies reported plasma hs-CRP, 4 serum hs-CRP, 1 plasma CRP, and 2 serum CRP levels. Compared to controls, the pooled MD of plasma hs-CRP levels in adults with OSA was 0.11 mg/dL (p < 0.00001). Compared to controls, the pooled MD of serum hs-CRP levels in adults with OSA was 0.09 mg/dL (p < 0.00001). Compared to controls, the pooled MD of plasma CRP levels in adults with OSA was 0.06 mg/dL (p = 0.72). Compared to controls, the pooled MD of serum CRP levels in adults with OSA was 0.36 mg/dL (p < 0.00001). Compared to controls, the pooled MD of plasma hs-CRP, serum hs-CRP, plasma hs-CRP, and serum hs-CRP in children with OSA was 1.17 mg/dL (p = 0.005), 0.18 mg/dL (p = 0.05), 0.08 mg/dL (p = 0.10), and 0.04 mg/dL (p = 0.33), respectively. The meta-regression showed that with a greater apnea-hypapnea index (AHI), serum hs-CRP levels were significantly higher. (4) Conclusions: The results of the present systematic review, meta-analysis and meta-regression showed that compared to healthy controls plasma and serum levels of hs-CRP and serum CRP level were higher in adults with OSA; for children, and compared to controls, just plasma hs-CRP levels in children with OSA were higher.

The Role of Soluble Low-Density Lipoprotein Receptor-Related Protein-1 in Obstructive Sleep Apnoea

Intermittent hypoxia in obstructive sleep apnoea (OSA) is related to inflammation and metabolic abnormalities. Soluble low-density lipoprotein receptor-related protein-1 (sLRP-1) is involved in anti-inflammatory and metabolic processes. However, its ligand, calreticulin (CALR) promotes pro-inflammatory responses and apoptosis. Our aim was to analyse the levels of these biomarkers in OSA. We recruited 46 patients with OSA and 30 control subjects. Inpatient sleep study was performed and fasting plasma samples were collected. Triglyceride glucose index (TyG) and atherogenic index of plasma (AIP) were calculated. Plasma sLRP-1 levels were significantly lower in the OSA group compared to the controls (1.67 (0.90–2.11) mg/L vs. 1.99 (1.53–3.51) mg/L; p = 0.04) after adjustment for age, gender, BMI and lipid profile. Plasma sLRP-1 concentrations were inversely related to age (r = −0.29), BMI (r = −0.35), cigarette pack years (r = −0.31), LDL-C (r = −0.34) and triglyceride levels (r = −0.27), TyG (r = −0.37) and AIP (r = −0.27) as well as to the oxygen desaturation index (ODI, r = −0.24; all p < 0.05). BMI (p = 0.01) and ODI (p = 0.04) were independent predictors for low sLRP-1 levels. CALR did not differ significantly between the two groups (0.23 (0.17–0.34) ng/mL vs. 0.24 (0.20–0.36) ng/mL p = 0.76). We detected lower sLRP-1 levels in subjects with OSA which could contribute to metabolic abnormalities associated with this disease.

Coagulation and Fibrinolysis in Obstructive Sleep Apnoea

Obstructive sleep apnoea (OSA) is a common disease which is characterised by repetitive collapse of the upper airways during sleep resulting in chronic intermittent hypoxaemia and frequent microarousals, consequently leading to sympathetic overflow, enhanced oxidative stress, systemic inflammation, and metabolic disturbances. OSA is associated with increased risk for cardiovascular morbidity and mortality, and accelerated coagulation, platelet activation, and impaired fibrinolysis serve the link between OSA and cardiovascular disease. In this article we briefly describe physiological coagulation and fibrinolysis focusing on processes which could be altered in OSA. Then, we discuss how OSA-associated disturbances, such as hypoxaemia, sympathetic system activation, and systemic inflammation, affect these processes. Finally, we critically review the literature on OSA-related changes in markers of coagulation and fibrinolysis, discuss potential reasons for discrepancies, and comment on the clinical implications and future research needs.

Circulating levels of clusterin and complement factor H in patients with obstructive sleep apnea

Aim: Obstructive sleep apnea (OSA) activates the complement system; however, the levels of membrane attack complex (MAC) are unaltered suggesting regulatory mechanisms. Our aim was to investigate complement factor H (CFH) and clusterin, two important complement regulators in OSA. Materials & methods: We analyzed clusterin and CFH levels in plasma of 86 patients with OSA and 33 control subjects. Results: There was no difference in CFH levels between patients (1099.4/784.6-1570.5/μg/ml) and controls (1051.4/652.0-1615.1/μg/ml, p = 0.72). Clusterin levels were higher in patients with OSA (309.7/217.2-763.2/μg/ml vs 276.1/131.0-424.3/μg/ml, p = 0.048) with a trend for a positive correlation with disease severity (p = 0.073). Conclusion: Increase in clusterin levels may be protective in OSA by blocking the MAC formation.

The role of hyaluronic acid and hyaluronidase-1 in obstructive sleep apnoea

Biological functions of hyaluronic acid (HA) depend on its molecular size. High-molecular weight HA (HMW-HA) is an important component of the endothelial wall and has anti-inflammatory and antioxidant properties. Under inflammation or hypoxia, HMW-HA is degraded by hyaluronidases, such as HYAL-1 resulting in pro-inflammatory low-molecular weight fragments. Obstructive sleep apnoea (OSA) is characterised by intermittent hypoxia and systemic inflammation. Our aim was to evaluate circulating HMW-HA and HYAL-1 in OSA. We recruited 68 patients with OSA and 40 control volunteers. After full-night sleep study blood samples were taken for HMW-HA and HYAL-1 measurements. HYAL-1 levels were significantly higher in patients with OSA compared to controls (0.59/0.31-0.88/ng/mL vs. 0.31/0.31-0.58/ng/mL; p = 0.005) after adjustment for gender, age, BMI and smoking. There was a trend for reduced HMW-HA concentrations in OSA (31.63/18.11-59.25/ng/mL vs. 46.83/25.41-89.95/ng/mL; p = 0.068). Significant correlation was detected between circulating HMW-HA and apnoea-hypopnoea-index (r = - 0.195, p = 0.043), HYAL-1 and apnoea-hypopnoea-index (r = 0.30, p < 0.01) as well as oxygen desaturation index (r = 0.26, p < 0.01). Our results suggest that chronic hypoxia is associated with increased plasma HYAL-1 concentration and accelerated HMW-HA degradation. Altered hyaluronan metabolism may be involved in the inflammatory cascade potentially leading to endothelial dysfunction in OSA.

Downregulation of serum survivin correlates with increased inflammation, enhanced disease severity and worse prognosis in sepsis patients

This study aimed to determine the role of survivin in sepsis patients.Serum samples of 288 sepsis patients and 290 healthy individuals (as healthy controls) were collected 24 hours within enrollment. Serum survivin and inflammatory cytokines were detected by enzyme-linked immunosorbent assay, and biochemical indexes were recorded. In sepsis patients, acute pathologic and chronic health evaluation II score and sequential organ failure assessment score were evaluated, and 28-day mortality was recorded.Survivin was greatly decreased in sepsis patients compared to healthy controls (P < .001) and it predicted decreased sepsis risk (area under curve (AUC): 0.921, 95% confidence interval (CI): 0.900-0.942). For clinical characteristics of sepsis patients, survivin was negatively correlated with acute pathologic and chronic health evaluation II score (P < .001), score and sequential organ failure assessment score (P < .001), serum creatinine (P < .001), white blood cell (P = .037), C-reactive protein (P < .001), tumor necrosis factor-α (P < .001), interleukin (IL)-1β (P < .001), IL-6 (P < .001), and IL-8 (P < .001), while positively correlated with albumin (P < .001). For prognosis of sepsis patients, survivin was decreased in deaths compared to survivors (P < .001), and it predicted decreased death risk (AUC: 0.625, 95% CI: 0.558-0.692). Meanwhile, accumulating mortality was decreased in survivin high patients compared to survivin low patients (P = .006). However, multivariate logistic regression revealed survivin was not an independent predictive factor for 28-day mortality, indicating it might interact with other independent factors to affect prognosis of sepsis patients.Survivin was decreased in sepsis patients and predicted decreased sepsis risk. Meanwhile, survivin was correlated with declined inflammation, reduced disease severity, and favorable prognosis in sepsis patients.

Circulating Soluble Urokinase-Type Plasminogen Activator Receptor in Obstructive Sleep Apnoea

Background and Objectives: Obstructive sleep apnoea (OSA) is associated with heightened systemic inflammation and a hypercoagulation state. Soluble urokinase-type plasminogen activator receptor (suPAR) plays a role in fibrinolysis and systemic inflammation. However, suPAR has not been investigated in OSA. Materials and Methods: A total of 53 patients with OSA and 15 control volunteers participated in the study. Medical history was taken and in-hospital sleep studies were performed. Plasma suPAR levels were determined by ELISA. Results: There was no difference in plasma suPAR values between patients with OSA (2.198 ± 0.675 ng/mL) and control subjects (2.088 ± 0.976 ng/mL, p = 0.62). Neither was there any difference when patients with OSA were divided into mild (2.134 ± 0.799 ng/mL), moderate (2.274 ± 0.597 ng/mL) and severe groups (2.128 ± 0.744 ng/mL, p = 0.84). There was no significant correlation between plasma suPAR and indices of OSA severity, blood results or comorbidities, such as hypertension, diabetes, dyslipidaemia or cardiovascular disease. Plasma suPAR levels were higher in women when all subjects were analysed together (2.487 ± 0.683 vs. 1.895 ± 0.692 ng/mL, p < 0.01), and also separately in controls (2.539 ± 0.956 vs. 1.411 ± 0.534 ng/mL, p = 0.02) and patients (2.467 ± 0.568 vs. 1.991 ± 0.686 ng/mL, p < 0.01). Conclusions: Our results suggest that suPAR does not play a significant role in the pathophysiology of OSA. The significant gender difference needs to be considered when conducting studies on circulating suPAR.

Circulating P-Selectin Glycoprotein Ligand 1 and P-Selectin Levels in Obstructive Sleep Apnea Patients

Purpose

Obstructive sleep apnea (OSA) is characterized by chronic intermittent hypoxia which induces inflammation in blood vessels leading to the development of cardiovascular comorbidities. Several studies implicated the role of P-selectin in vascular inflammation of OSA. P-selectin glycoprotein ligand 1 (PSGL-1) is the main activator for P-selectin and is involved in immune cell trafficking. However, PSGL-1 has not been analyzed in OSA. The aim of the study was to investigate plasma PSGL-1 and P-selectin levels to have a deeper understanding on their interaction in obstructive sleep apnea.

Methods

Fifty-one untreated patients with OSA and 42 non-OSA controls were recruited. Plasma PSGL-1 levels were determined in evening and morning samples, P-selectin levels were analyzed in morning samples using commercially available ELISA kits. Polysomnography was performed in all participants. OSA was defined by an apnea–hypopnea index ≥ 5/h.

Results

PSGL-1 levels did not differ between controls and OSA patients either in the evening or in the morning. Although, there was no difference between controls (16.9/6.8–40.8 ng/ml) and patients with OSA (19.6/8.4–56.8, p = 0.24), patients with severe OSA had increased plasma P-selectin levels (25.6/8.4–56.8 ng/ml) compared to mild OSA patients (14.1/8.5–35.3 ng/ml, p = 0.006) and controls (p = 0.03).

Conclusions

P-selectin expression relates to disease severity suggesting a pathophysiological role in endothelial cell activation. PSGL-1 levels are unaltered in OSA, suggesting an alternative activation pathway for P-selectin in OSA.

Decreased Levels of Anti-Aging Klotho in Obstructive Sleep Apnea

The klotho protein is secreted primarily by the kidneys. It is responsible for phosphate homeostasis and has an anti-aging, anti-inflammatory, and anti-oxidative stress role. Obstructive sleep apnea (OSA) is associated with an enhanced systemic inflammation and oxidative stress, but mechanisms that regulate these processes are poorly understood. The aim of the study was to investigate the plasma levels of klotho in OSA. Twenty-one previously untreated patients with OSA (56 ± 13 years, 12 males) and 41 non-OSA control volunteers (48 ± 16 years, 8 males) participated in the study. Medical history has been taken; participants filled out the Epworth Sleepiness Scale. C-reactive protein and renal function, glucose and lipid profile measurements were performed in sera; klotho was determined in citrate-treated plasma samples. Levels of plasma klotho were decreased in OSA (519.1 ± 164.9 pg/mL) versus controls (700.8 ± 431.4 pg/mL, p = 0.02). Reduced klotho concentrations were associated with markers of overnight hypoxemia determined with O₂ desaturation index (r = -0.31, p = 0.01), percentage of sleep time spent with saturation <90% (r = -0.41, p < 0.01), and minimal saturation during sleep (r = 0.33, p = 0.01). Interestingly, there was no relationship with apnea-hypopnea index, total sleep time, or arousal index (all p > 0.05). Significant association was also found between low plasma klotho levels and the presence of hypertension (p < 0.05). Our results suggest that chronic intermittent hypoxia reduces the levels of klotho in OSA, which may contribute to the development of hypertension. Decreased klotho levels may play a role in enhanced systemic inflammation in OSA and may be a future target for drug development.