Roles and Mechanisms of Obstructive Sleep Apnea-Hypopnea Syndrome and Chronic Intermittent Hypoxia in Atherosclerosis: Evidence and Prospective

HIF-1α mediates hypertension and vascular remodeling in sleep apnea via hippo-YAP pathway activation

BACKGROUND

Sleep apnea syndrome (SAS) is associated with hypertension and vascular remodeling. Hypoxia-inducible factor-1α (HIF-1α) and the Hippo-YAP pathway are implicated in these processes, but their specific roles remain unclear. This study investigated the HIF-1α/Hippo-YAP pathway in SAS-related hypertension.

METHODS

We established a rat model of SAS-induced hypertension via chronic intermittent hypoxia (CIH). Rats were treated with siRNA targeting HIF-1α. Blood pressure, inflammation, oxidative stress, vascular remodeling, and VSMC function were assessed. In vitro experiments with A7r5 cells and human aortic smooth muscle cells (HAoSMCs) explored the effects of HIF-1α silencing and YAP1 overexpression.

RESULTS

Compared with the control group, the CIH group presented significant increases in both HIF-1α and YAP1 expression, which correlated with increased blood pressure and vascular changes. HIF-1α silencing reduced hypertension, oxidative stress, inflammation, and the severity of vascular remodeling. Specifically, siRNA treatment for HIF-1α normalized blood pressure, decreased the levels of oxidative damage markers (increased SOD and decreased MDA), and reversed the changes in the levels of inflammatory markers (decreased high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6) and soluble E-selectin (sE-s)). Structural analyses revealed reduced vascular smooth muscle cell proliferation and collagen deposition, along with normalization of cellular markers, such as α-SMA and TGF-β1. Furthermore, the Hippo-YAP pathway appeared to mediate these effects, as evidenced by altered YAP1 expression and activity upon HIF-1α modulation.

CONCLUSIONS

Our findings demonstrate the significance of the HIF-1α/Hippo-YAP pathway in CIH-induced hypertension and vascular remodeling. HIF-1α contributes to these pathophysiological processes by promoting oxidative stress, inflammation, and aberrant VSMC behavior. Targeting this pathway could offer new therapeutic strategies for CIH-related cardiovascular complications in SAS patients.

An Artificial Intelligence-Based Non-Invasive Approach for Cardiovascular Disease Risk Stratification in Obstructive Sleep Apnea Patients: A Narrative Review

Background

Obstructive sleep apnea (OSA) is a severe condition associated with numerous cardiovascular complications, including heart failure. The complex biological and morphological relationship between OSA and atherosclerotic cardiovascular disease (ASCVD) poses challenges in predicting adverse cardiovascular outcomes. While artificial intelligence (AI) has shown potential for predicting cardiovascular disease (CVD) and stroke risks in other conditions, there is a lack of detailed, bias-free, and compressed AI models for ASCVD and stroke risk stratification in OSA patients. This study aimed to address this gap by proposing three hypotheses: (i) a strong relationship exists between OSA and ASCVD/stroke, (ii) deep learning (DL) can stratify ASCVD/stroke risk in OSA patients using surrogate carotid imaging, and (iii) including OSA risk as a covariate with cardiovascular risk factors can improve CVD risk stratification.

Methods

The study employed the Preferred Reporting Items for Systematic reviews and Meta-analyses (PRISMA) search strategy, yielding 191 studies that link OSA with coronary, carotid, and aortic atherosclerotic vascular diseases. This research investigated the link between OSA and CVD, explored DL solutions for OSA detection, and examined the role of DL in utilizing carotid surrogate biomarkers by saving costs. Lastly, we benchmark our strategy against previous studies.

Results

(i) This study found that CVD and OSA are indirectly or directly related. (ii) DL models demonstrated significant potential in improving OSA detection and proved effective in CVD risk stratification using carotid ultrasound as a biomarker. (iii) Additionally, DL was shown to be useful for CVD risk stratification in OSA patients; (iv) There are important AI attributes such as AI-bias, AI-explainability, AI-pruning, and AI-cloud, which play an important role in CVD risk for OSA patients.

Conclusions

DL provides a powerful tool for CVD risk stratification in OSA patients. These results can promote several recommendations for developing unique, bias-free, and explainable AI algorithms for predicting ASCVD and stroke risks in patients with OSA.

Raloxifene Protects Oxygen-Glucose-Deprived Astrocyte Cells Used to Mimic Hypoxic-Ischemic Brain Injury

Perinatal asphyxia (PA) is a clinical condition characterized by oxygen supply suspension before, during, or immediately after birth, and it is an important risk factor for neurodevelopmental damage. Its estimated 1/1000 live births incidence in developed countries rises to 5-10-fold in developing countries. Schizophrenia, cerebral palsy, mental retardation, epilepsy, blindness, and others are among the highly disabling chronic pathologies associated with PA. However, so far, there is no effective therapy to neutralize or reduce PA-induced harm. Selective regulators of estrogen activity in tissues and selective estrogen receptor modulators like raloxifene have shown neuroprotective activity in different pathological scenarios. Their effect on PA is yet unknown. The purpose of this paper is to examine whether raloxifene showed neuroprotection in an oxygen-glucose deprivation/reoxygenation astrocyte cell model. To study this issue, T98G cells in culture were treated with a glucose-free DMEM medium and incubated at 37 °C in a hypoxia chamber with 1% O2 for 3, 6, 12, and 24 h. Cultures were supplemented with raloxifene 10, and 100 nM during both glucose and oxygen deprivation and reoxygenation periods. Raloxifene 100 nM and 10 nM improved cell survival-65.34% and 70.56%, respectively, compared with the control cell groups. Mitochondrial membrane potential was preserved by 58.9% 10 nM raloxifene and 81.57% 100 nM raloxifene cotreatment. Raloxifene co-treatment reduced superoxide production by 72.72% and peroxide production by 57%. Mitochondrial mass was preserved by 47.4%, 75.5%, and 89% in T98G cells exposed to 6-h oxygen-glucose deprivation followed by 3, 6, and 9 h of reoxygenation, respectively. Therefore, raloxifene improved cell survival and mitochondrial membrane potential and reduced lipid peroxidation and reactive oxygen species (ROS) production, suggesting a direct effect on mitochondria. In this study, raloxifene protected oxygen-glucose-deprived astrocyte cells, used to mimic hypoxic-ischemic brain injury. Two examiners performed the qualitative assessment in a double-blind fashion.

Mitigating Increased Cardiovascular Risk in Patients with Obstructive Sleep Apnea Using GLP-1 Receptor Agonists and SGLT2 Inhibitors: Hype or Hope?

Obstructive sleep apnea (OSA) is a prevalent condition associated with increased cardiovascular risk, particularly in individuals with comorbid obesity and type 2 diabetes (T2D). Despite the widespread use of continuous positive airway pressure (CPAP) for OSA management, adherence remains suboptimal, and CPAP has not consistently demonstrated reductions in surrogate cardiovascular events. Recently, attention has focused on glucagon-like peptide-1 receptor agonists (GLP-1RAs) and sodium-glucose cotransporter-2 (SGLT2) inhibitors as potential therapeutic agents for mitigating cardiovascular risk in OSA patients. These agents, originally developed for T2D management, have demonstrated pleiotropic effects, including significant weight loss, blood pressure reduction, and amelioration of endothelial dysfunction and arterial stiffness, along with anti-inflammatory benefits, which may be particularly beneficial in OSA. Emerging clinical evidence suggests that GLP-1RAs and SGLT2 inhibitors can reduce OSA severity and improve daytime sleepiness, potentially reversing the adverse cardiovascular effects observed in OSA. This review explores the pathophysiological mechanisms linking OSA with cardiovascular disease and evaluates the potential therapeutic roles of GLP-1RAs and SGLT2 inhibitors in addressing cardiovascular risk in OSA patients. Further research, including long-term clinical trials, is necessary to establish the effectiveness of these therapies in reducing cardiovascular events and improving patients' reported outcomes in this population.

The immune response to arterial damage in a mouse model of intermittent hypoxia: a transcriptomics analysis

PURPOSE

Mice can develop arterial damage and even atherosclerosis under intermittent hypoxia (IH); however, the specific mechanism of arterial damage induced by IH remains unclear. Hence, this research aimed to illustrate the underlying mechanism linking IH to arterial injury.

MATERIALS AND METHODS

The differential gene expression of the thoracic aorta under normoxia or IH mice was analyzed utilizing RNA sequencing. Furthermore, GO, KEGG pathway, and CIBERSORT analyses were carried out. For verification of the expression of candidate genes affected by IH, quantitative RT-qPCR (qRT-PCR) was conducted. Immunohistochemical (IHC) staining revealed immune cell infiltration in the thoracic aorta.

RESULTS

The thickness of the intima-media of the mouse aorta was increased, and the fiber structure was disordered under IH. Transcriptomics analysis showed that in the aorta, 1137 upregulated genes and 707 downregulated genes were affected by IH, significantly related to the activation of the immune system and cell adhesion. Furthermore, B cell infiltration around the aorta was observed under IH.

CONCLUSIONS

IH might lead to structural changes in the aorta by activating the immune response and enhancing cell adhesion.

Sacubitril/valsartan mitigated intermittent hypoxia related intestinal microbiota alteration and aortic injury

OBJECTIVE

To investigate the influence of sacubitril valsartan sodium (SVS) on chronic intermittent hypoxia (IH) related gut microbiome composition alteration and aortic injury.

METHODS

Experiments were performed using SD rats, which were divided into three groups: control, IH, and SVS group. O2 concentration was decreased to 7-8% at nadir approximately every 3 min in IH group (8 h per day for 6 weeks) or was left unchanged in control group. Rats in SVS group were orally gavaged with SVS at the dosage of 30 mg/kg/day (2 weeks after chronic IH exposure). At week 6, fecal and aortic samples were harvested for 16 s rDNA analysis and histological analysis, respectively.

RESULTS

Principal coordinate analysis and non-metric multidimensional scaling analysis indicated that the bacterial community was altered by chronic IH exposure, while SVS treatment restored the intestinal microbial communities. Further analysis showed that IH decreased the relative abundance of Lactobacillus and Prevotella, while rats treated with SVS was enriched with Firmicutes, Bacilli, Prevotellaceae, and Lactobacillus, which was similar to control rats. Immunohistochemical staining showed that SVS prevented the upregulation of transforming growth factor-β1 and tumor necrosis factor-alpha in the aorta.

CONCLUSION

SVS prevented aortic adverse response to IH, possibly through modulating intestinal microbiota.

Obstructive sleep apnoea heterogeneity and cardiovascular disease

Obstructive sleep apnoea (OSA), characterized by recurrent periods of upper airway obstruction and intermittent hypoxaemia, is prevalent in patients with cardiovascular disease (CVD), and is therefore important to consider in the prevention and management of CVD. Observational studies indicate that OSA is a risk factor for incident hypertension, poorly controlled blood pressure, stroke, myocardial infarction, heart failure, cardiac arrhythmias, sudden cardiac death and all-cause death. However, clinical trials have not provided consistent evidence that treatment with continuous positive airway pressure (CPAP) improves cardiovascular outcomes. These overall null findings might be explained by limitations in trial design and low levels of adherence to CPAP. Studies have also been limited by the failure to consider OSA as a heterogeneous disorder that consists of multiple subtypes resulting from variable contributions from anatomical, physiological, inflammatory and obesity-related risk factors, and resulting in different physiological disturbances. Novel markers of sleep apnoea-associated hypoxic burden and cardiac autonomic response have emerged as predictors of OSA-related susceptibility to adverse health outcomes and treatment response. In this Review, we summarize our understanding of the shared risk factors and causal links between OSA and CVD and emerging knowledge on the heterogeneity of OSA. We discuss the varied mechanistic pathways that result in CVD that also vary across subgroups of OSA, as well as the potential role of new biomarkers for CVD risk stratification.

Recent progress of biocompatible carbon dots in hypoxia-related fields

Almost all eukaryotes need oxygen to maintain regular physiological activities. When the organism is under hypoxic situation for a persistent or periodic, it will induce irreversible physiological disorders and even pathological results. Hypoxia is closely related to the pathogenesis of metabolic diseases, cancer, chronic heart disease and kidney disease, myocardial ischemia, as well as reproductive diseases like preeclampsia and endometriosis. Therefore, monitoring and treatment of hypoxia have important implications for the pathophysiology of human-related diseases. Carbon dots (CDs) are emerging nanomaterials developed after 2004 with excellent performance, and have broad application potential in variousdomains likeoptical, biomedicine, energy. Advanced hypoxia therapeutics should be integrated with monitoring and treatment, and CDs with excellent performance are good potential options when sensing is combined with various therapeutic methods. Some researchers have also begun to carry out research in related fields and achieved some results. This article aims to clarify the various applications of CDs in hypoxia-related fields in recent years, including hypoxia sensing and hypoxia tumor theranostics. Finally, the possible challenges and prospects for the application of CDs in hypoxia-related fields are discussed.

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.

Association between obstructive sleep apnea and cardiovascular diseases

Obstructive sleep apnea (OSA) is a common respiratory disorder characterized by partial obstruction of upper respiratory tract and repetitive cessation of breathing during sleep. The etiology behind OSA is associated with the occurrence of intermittent hypoxemia, recurrent arousals and intrathoracic pressure swings. These contributing factors may turn on various signaling mechanisms including elevated sympathetic tone, oxidative stress, inflammation, endothelial dysfunction, cardiovascular variability, abnormal coagulation and metabolic defect ( e.g., insulin resistance, leptin resistance and altered hepatic metabolism). Given its close tie with major cardiovascular risk factors, OSA is commonly linked to the pathogenesis of a wide array of cardiovascular diseases (CVDs) including hypertension, heart failure, arrhythmias, coronary artery disease, stroke, cerebrovascular disease and pulmonary hypertension (PH). The current standard treatment for OSA using adequate nasal continuous positive airway pressure (CPAP) confers a significant reduction in cardiovascular morbidity. Nonetheless, despite the availability of effective therapy, patients with CVDs are still deemed highly vulnerable to OSA and related adverse clinical outcomes. A better understanding of the etiology of OSA along with early diagnosis should be essential for this undertreated disorder in the clinical setting.

Study on the Changes of Liver and Kidney Function-Related Indicators and Clinical Significance in Patients with OSAHS

Purpose

To study the changes of liver and kidney function-related indexes in patients with obstructive sleep apnea hypopnea syndrome (OSAHS) and analyze their clinical significance.

Method

Ninety OSAHS patients treated in our hospital from April 2019 to April 2021 were selected. According to the apnea-hypopnea Index (AHI), they were divided into mild OSAHS group (5 ≤ AHI < 15 times/h, 35 people), moderate OSAHS group (15 ≤ AHI < 30 times/h, 35 people), and severe OSAHS group (AHI ≥ 30 times/h, 20 people). In addition, 50 healthy people who underwent physical examination in our hospital at the same time were selected as the control group, and the liver and kidney function and polysomnography (PSG)-related indexes of the above subjects were detected, and the comparison between the groups was carried out.

Result

The serum BUN and SCR levels of the severe group were significantly higher than those of the moderate group, the moderate group had significantly higher levels than the mild group, and the mild group had significantly higher levels than the control group (P < 0.05). The blood AST level of the severe group was significantly lower than that of the moderate group, the moderate group had a significantly lower level than the mild group, and the mild group had a significantly lower level than the control group (P < 0.05). The blood ALT level of the severe group was significantly higher than that of the moderate group, the moderate group had significantly a higher level than the mild group, and the mild group had a significantly higher level than the control group (P < 0.05). The proportions of abnormal liver and kidney function in the control group, mild group, moderate group, and severe group were significantly different (P < 0.05). The AHI of the severe group was significantly higher than that of the moderate group, the moderate group had a higher value than the mild group, and the mild group had a higher value than the control group (P < 0.05). The ASpO2 and MSpO2 of the severe group were significantly lower than those of the moderate group, the moderate group had significantly lower values than the mild group, and the mild group had significantly lower values than the control group (P < 0.05). Spearman correlation analysis showed that the liver and kidney function indexes of OSAHS patients were significantly correlated with PSG indexes (P < 0.05).

Conclusion

Patients with OSAHS will have obvious liver and kidney dysfunction, and the monitoring of liver and kidney function in such patients should be strengthened. If abnormality occurs, early intervention is recommended.

Morin mitigates ifosfamide induced nephrotoxicity by regulation of NF-kappaB/p53 and Bcl-2 expression

Ifosfamide (IFO) is used for treating childhood solid tumors, but its use is limited by its adverse effects on kidneys. Morin may be used to prevent nephrotoxic and other side effects. We investigated the underlying mechanisms of the protective effects of morin on IFO induced nephrotoxicity. We used 35 male rats divided into five groups of seven: control group, morin group, IFO group, 100 mg/kg morin + IFO group and 200 mg/kg morin + IFO group. We measured kidney tissue oxidant, antioxidant and inflammatory parameters using ELISA, and apoptosis was evaluated using immunohistochemistry and real time PCR. Serum urea, creatinine and kidney injury molecule-1 (KIM-1) levels were increased by IFO treatment; elevated levels were decreased significantly by treatment with both 100 and 200 mg/kg morin. Morin treatment also decreased oxidative stress and lipid oxidation in IFO treated rats. The ameliorative effect of morin on inflammatory response was due to reduced levels of NF-κB and TNF-α. Morin also reduced NF-κB/p53 levels by increasing Bcl-2 expression in IFO treated kidneys. Morin may prevent IFO induced nephrotoxicity via the NF-κB/p53 and Bcl-2 signaling pathways.

Independent Association Between Oxygen Desaturation Index and Cardiovascular Disease in Non-Sleepy Sleep-Disordered Breathing Subtype: A Chinese Community-Based Study

PURPOSE

Non-sleepy sleep-disordered breathing (SDB) is increasingly recognized as an important clinical subtype. The association between non-sleepy SDB and cardiovascular disease (CVD) is not well understood. Our objectives were to investigate the relationship between non-sleepy SDB and CVD and determine which nocturnal hypoxia parameter most strongly reflects this association in a large community population.

PATIENTS AND METHODS

Cross-sectional data from 3626 randomly-selected Chinese community-dwelling participants who underwent overnight type IV sleep monitoring were analyzed. Parameters of nocturnal hypoxemia were extracted from sleep monitoring devices, including mean nocturnal oxygen saturation, lowest oxygen saturation, oxygen desaturation index (ODI), and time with oxygen saturation <90%. An ODI ≥7.0 events/h was considered to signify SDB. An Epworth Sleepiness Scale score of 10 or less indicated no sleepiness.

RESULTS

The SDB rate was 30.7% (1114/3626), of which 96.5% (1075/1114) were considered the non-sleepy SDB subtype. ODI, typical nocturnal intermittent hypoxia indicator for SDB, was independently related to CVD, regardless of whether excessive daytime sleepiness was present. After adjusting for confounders, ODI most strongly reflected the association between non-sleepy SDB and CVD (OR:1.023; 95% CI:1.003-1.043). We observed a nonlinear association between ODI and the prevalence of CVD, where the likelihood of CVD increased with ODI≥10 events/h and a markedly increasing trend was observed with ODI ≥20 events/h (reference ODI = 7.0 events/h). Metabolic parameters, Pittsburgh Sleep Quality Index, and inflammatory marker did not mediate the association between ODI and CVD in the non-sleepy SDB subtype.

CONCLUSION

In the Chinese community-dwelling population, non-sleepy SDB was highly prevalent. ODI, an easily extracted indicator from a type IV sleep monitor, most strongly reflected the association between non-sleepy SDB and CVD.

Development and Comparison of Predictive Models Based on Different Types of Influencing Factors to Select the Best One for the Prediction of OSAHS Prevalence

OBJECTIVE

This study aims to retrospectively analyze numerous related clinical data to identify three types of potential influencing factors of obstructive sleep apnea-hypopnea syndrome (OSAHS) for establishing three predictive nomograms, respectively. The best performing one was screened to guide further clinical decision-making.

METHODS

Correlation, difference and univariate logistic regression analysis were used to identify the influencing factors of OSAHS. Then these factors are divided into three different types according to the characteristics of the data. Lasso regression was used to filter out three types of factors to construct three nomograms, respectively. Compare the performance of the three nomograms evaluated by C-index, ROC curve and Decision Curve Analysis to select the best one. Two queues were obtained by randomly splitting the whole queue, and similar methods are used to verify the performance of the best nomogram.

RESULTS

In total, 8 influencing factors of OSAHS have been identified and divided into three types. Lasso regression finally determined 6, 3 and 4 factors to construct mixed factors nomogram (MFN), baseline factors nomogram (BAFN) and blood factors nomogram (BLFN), respectively. MFN performed best among the three and also performed well in multiple queues.

CONCLUSION

Compared with BAFN and BLFN constructed by single-type factors, MFN constructed by six mixed-type factors shows better performance in predicting the risk of OSAHS.

Chronic Intermittent Hypoxia Regulates CaMKII-Dependent MAPK Signaling to Promote the Initiation of Abdominal Aortic Aneurysm

Obstructive sleep apnea (OSA) is highly prevalent in patients with abdominal aortic aneurysm (AAA). However, the effects of OSA on AAA initiation in a murine model of sleep apnea have not been completely studied. In this paper, Apoe^−/− C57BL/6 mice infused with angiotensin II (Ang II) were placed in chronic intermittent hypoxia (CIH) condition for inducing OSA-related AAA. CIH significantly promoted the incidence of AAA and inhibited the survival of mice. By performing ultrasonography and elastic Van Gieson staining, CIH was found to be effective in promoting aortic dilation and elastin degradation. Immunohistochemical and zymography results show that CIH upregulated the expression and activity of MMP2 and MMP9 and upregulated MCP1 expression while downregulating α-SMA expression. Also, CIH exposure promoted ROS generation, apoptosis, and mitochondria damage in vascular smooth muscle cells (VSMCs), which were measured by ROS assay, TUNEL staining, and transmission electron microscopy. The result of RNA sequencing of mouse aortas displayed that 232 mRNAs were differently expressed between Ang II and Ang II+CIH groups, and CaMKII-dependent p38/Jnk was confirmed as one downstream signaling of CIH. CaMKII-IN-1, an inhibitor of CaMKII, eliminated the effects of CIH on the loss of primary VSMCs. To conclude, a mouse model of OSA-related AAA, which contains the phenotypes of both AAA and OSA, was established in this study. We suggested CIH as a risk factor of AAA initiation through CaMKII-dependent MAPK signaling.

Effects of Continuous Positive Airway Pressure on Cell Adhesion Molecules in Patients with Obstructive Sleep Apnea: A Meta-Analysis

PURPOSE

Previous studies have confirmed that patients with obstructive sleep apnea (OSA) have higher systemic inflammatory markers, including intercellular adhesion molecule-1(ICAM-1), vascular cell adhesion molecule-1(VCAM-1), and E-selectin compared to control subjects. However, the effects of continuous positive airway pressure (CPAP) therapy on circulating levels of ICAM-1, VCAM-1, and E-selectin in OSA patients remain inconsistent. Therefore, the primary purpose of the present meta-analysis is to estimate the effect of CPAP therapy on these cell adhesion molecules (CAMs) in patients with OSA.

METHODS

The PubMed, Scopus, Embase, and Cochrane Library databases were searched. The overall effects were measured by the standardized mean difference (SMD) with a 95% confidence interval (CI). A random effects model or a fixed-effects model was used, depending on the heterogeneity of the studies.

RESULTS

A total of 11 studies were included, comprising 650 OSA patients. The pooled results showed that CPAP therapy significantly decreased ICAM-1 (SMD =  - 0.283, 95% CI   - 0.464 to - 0.101, p = 0.002) and E-selectin levels (SMD =  - 0.349, 95% CI   - 0.566 to - 0.133, p = 0.002). In contrast, there was no significant improvement of VCAM-1 levels after CPAP treatment (SMD =  - 0.160, 95% CI   - 0.641 to 0.320, p = 0.513).

CONCLUSIONS

Our meta-analysis demonstrated that CPAP treatment significantly decreased the circulating levels of ICAM-1 and E-selectin in OSA patients. Thus, ICAM-1 and E-selectin may be effective markers to evaluate CPAP therapy for reducing OSA cardiovascular risk in clinical practice.

Brown Adipose Tissue Activation Is Involved in Atherosclerosis of ApoE-/- Mice Induced by Chronic Intermittent Hypoxia

Background: Obstructive sleep apnea is an atherogenesis factor of which chronic intermittent hypoxia is a prominent feature. Chronic intermittent hypoxia (CIH) exposure can sufficiently activate the sympathetic system, which acts on the β3 adrenergic receptors of brown adipose tissue (BAT). However, the activity of BAT and its function in CIH-induced atherosclerosis have not been fully elucidated.

Methods: This study involved ApoE^−/− mice which were fed with a high-fat diet for 12 weeks and grouped into control and CIH group. During the last 8 weeks, mice in the CIH group were housed in cages to deliver CIH (12 h per day, cyclic inspiratory oxygen fraction 5–20.9%, 180 s cycle). Atherosclerotic plaques were evaluated by Oil Red O, hematoxylin and eosin, Masson staining, and immunohistochemistry. Afterward, we conducted immunohistochemistry, western blotting, and qRT-PCR of uncoupling protein 1 (UCP1) to investigate the activation of BAT. The level of serum total cholesterol (TC), triglyceride, low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), and free fatty acid (FFA) were measured. Finally, RNA-Sequencing was deployed to explore the differentially expressed genes (DEGs) and their enriched pathways between control and CIH groups.

Results: Chronic intermittent hypoxia exposure promoted atherosclerotic plaque area with increasing CD68, α-SMA, and collagen in plaques. BAT activation was presented during CIH exposure with UCP1 up-regulated. Serum TC, triglyceride, LDL-c, and FFA were increased accompanied by BAT activation. HDL-c was decreased. Mechanistically, 43 lipolysis and lipid metabolism-associated mRNA showed different expression profiling between the groups. Calcium, MAPK, and adrenergic signaling pathway included the most gene number among the significantly enriched pathways.

Conclusion: This study first demonstrated that BAT activation is involved in the progression of CIH-induced atherosclerosis, possibly by stimulating lipolysis.

MKRN1 Ubiquitylates p21 to Protect against Intermittent Hypoxia-Induced Myocardial Apoptosis

Although chronic intermittent hypoxia- (IH-) induced myocardial apoptosis is an established pathophysiological process resulting in a poor prognosis for patients with obstructive sleep apnea syndrome, its underlying mechanism remains unclear. This study is aimed at exploring the role of makorin ring finger protein 1 (MKRN1) in IH-induced myocardial apoptosis and elucidating its molecular activity. First, the GSE2271 dataset was downloaded from the Gene Expression Omnibus database to identify the differentially expressed genes. Then, an SD rat model of IH, together with rat cardiomyocyte H9C2 and human cardiomyocyte AC16 IH models, was constructed. TUNEL, Western blot, and immunohistochemistry assays were used to detect cell apoptosis. Dihydroethidium staining was conducted to analyze the concentration of reactive oxygen species. In addition, RT-qPCR, Western blot, and immunohistochemistry were performed to measure the expression levels of MKRN1 and p21. The direct interaction between MKRN1 and p21 was determined using coimmunoprecipitation and ubiquitination analysis. MKRN1 expression was found to be downregulated in IH rat myocardial tissues as well as in H9C2 and AC16 cells. Upregulated expression of MKRN1 in H9C2 and AC16 cells alleviated the IH-induced reactive oxygen species production and cell apoptosis. Mechanistically, MKRN1 promoted p21 protein ubiquitination and the proteasome pathway degradation to negatively regulate p21 expression. Thus, MKRN1 regulates p21 ubiquitination to prevent IH-induced myocardial apoptosis.

Salidroside Ameliorated Intermittent Hypoxia-Aggravated Endothelial Barrier Disruption and Atherosclerosis via the cAMP/PKA/RhoA Signaling Pathway

Background: Endothelial barrier dysfunction plays a key role in atherosclerosis progression. The primary pathology of obstructive sleep apnea-hypopnea syndrome is chronic intermittent hypoxia (IH), which induces reactive oxygen species (ROS) overproduction, endothelial barrier injury, and atherosclerosis. Salidroside, a typical pharmacological constituent of Rhodiola genus, has documented antioxidative, and cardiovascular protective effects. However, whether salidroside can improve IH-aggravated endothelial barrier dysfunction and atherosclerosis has not been elucidated.

Methods and results: In normal chow diet-fed ApoE^−/− mice, salidroside (100 mg/kg/d, p. o.) significantly ameliorated the formation of atherosclerotic lesions and barrier injury aggravated by 7-weeks IH (21%–5%–21%, 120 s/cycle). In human umbilical vein endothelial cells (HUVECs), exposure to IH (21%–5%–21%, 40 min/cycle, 72 cycles) decreased transendothelial electrical resistance and protein expression of vascular endothelial cadherin (VE-cadherin) and zonula occludens 1. In addition, IH promoted ROS production and activated ras homolog gene family member A (RhoA)/Rho-associated protein kinase (ROCK) pathway. All of these effects of IH were reversed by salidroside. Similar to salidroside, ROCK-selective inhibitors Y26732, and Fasudil protected HUVECs from IH-induced ROS overproduction and endothelial barrier disruption. Furthermore, salidroside increased intracellular cAMP levels, while the PKA-selective inhibitor H-89 attenuated the effects of salidroside on IH-induced RhoA/ROCK suppression, ROS scavenging, and barrier protection.

Conclusion: Our findings demonstrate that salidroside effectively ameliorated IH-aggravated endothelial barrier injury and atherosclerosis, largely through the cAMP/PKA/RhoA signaling pathway.

[Changes of carotid artery elasticity before and after CPAP in patients with obstructive sleep apnea by ultrasonic ultrafast pulse wave velocity technique]

Objective:To examine the changes of carotid artery elasticity in patients with obstructive sleep apnea（OSA） before and after continuous positive airway pressure（CPAP） treatment by ultrafast pulse wave velocity（UFPWV） technique，and to explore the influencing factors of carotid artery elasticity in OSA patients，and to provide guidance for clinical prevention and treatment of cardiovascular complications. Methods：Fifty cases of moderate and severe OSA patients diagnosed with PSG monitoring from January 2020 to December 2020 were collected as the OSA group，at the same time，40 healthy subjects who participated in physical examination and matched with OSA group in age and gender were selected as the control group.The OSA group was treated with CPAP for 12 weeks.Clinical indicators，carotid intima-media thickness（IMT），and pulse wave velocity at the beginning of systole（PWVBS） and pulse wave velocity at the end of systole（PWVES） were recorded in the control group，and the above data were collected in the OSA group before and after treatment.The changes of various indicators between the control group and the OSA group，and between the OSA group before and after treatment were compared.The correlative factors and influencing factors of PWVBS and PWVES are analyzed. Results：The serum lipid indexes，IMT，PWVBS and PWVES in OSA group were higher than those in control group（P<0.05）.Comparison between post-treatment and pre-treatment with CPAP in OSA group：PWVBS，PWVES，apnea hypopnea index（AHI），blood oxygen saturation（SaO₂） less than 90% of the time，the percentage of monitoring time when SaO₂ was less than 90%（T90），low density lipoprotein cholesterol（LDL-C）and triglyceride（TG） were decreased（P<0.05）.Lowest blood oxygen saturation（LSaO₂） and high density lipoprotein cholesterol（HDL-C） increased（P<0.05）.Age，systolic blood pressure，IMT，AHI，T90 and time of oxygen saturation below 90% were positively correlated with PWVBS and PWVES，while HDL-C and LSaO₂ were negatively correlated with them（P<0.05）.The risk factors of PWVBS and PWVES included systolic blood pressure，AHI，TC，T90.Conclusion：Moderate and severe OSA can reduce arterial elasticity.CPAP can improve carotid artery elasticity function in patients with OSA.UFPWV technique is more sensitive to quantitatively evaluate the changes of arterial elasticity in patients with OSA than traditional two-dimensional ultrasound.

Mirabegron Ameliorated Atherosclerosis of ApoE-/- Mice in Chronic Intermittent Hypoxia but Not in Normoxia

PURPOSE

It has been established that obstructive sleep apnea (OSA) is an independent risk factor for atherosclerosis. Chronic intermittent hypoxia (CIH) activates sympathoadrenal system and upregulates β3 adrenergic receptor (β3 AR). However, the effect of selective β3 AR agonist mirabegron in CIH-induced atherosclerosis remains unknown.

METHODS

We generated a CIH-induced atherosclerosis model through exposing ApoE^-/- mice to CIH (8 h per day, cyclic inspiratory oxygen fraction 5-21%, 60-s cycle) for 6 weeks after 4-week high-fat dieting and investigated the effects of mirabegron, a selective β3 AR agonist, on CIH-induced atherosclerosis. The coronary endarterectomy (CE) specimens from coronary artery disease patients with OSA and without OSA were collected.

RESULTS

The expression of β3 AR was significantly elevated in CIH-induced atherosclerosis model. Furthermore, treatment with mirabegron (10mg/kg per day by oral administration for 6 weeks) ameliorated atherosclerosis in ApoE^-/- mice in CIH but not in normoxia. Mechanistically, mirabegron activated β3 AR and ameliorated intraplaque oxidative stress by suppressing p22phox expression and reactive oxygen species (ROS) level. In addition, in human CE specimens, β3 AR was also upregulated associated with increased p22phox expression and ROS level both in the lumen and in the plaque of coronary artery in OSA subjects.

CONCLUSION

This study first demonstrated that mirabegron impeded the progression of CIH-induced atherosclerosis, at least in part, via β3 AR-mediated oxidative stress, suggesting a promising therapeutic strategy for protecting against atherosclerosis induced by CIH.

An Update on Obstructive Sleep Apnea for Atherosclerosis: Mechanism, Diagnosis, and Treatment

The occurrence and development of atherosclerosis could be influenced by intermittent hypoxia. Obstructive sleep apnea (OSA), characterized by intermittent hypoxia, is world-wide prevalence with increasing morbidity and mortality rates. Researches remain focused on the study of its mechanism and improvement of diagnosis and treatment. However, the underlying mechanism is complex, and the best practice for OSA diagnosis and treatment considering atherosclerosis and related cardiovascular diseases is still debatable. In this review, we provided an update on research in OSA in the last 5 years with regard to atherosclerosis. The processes of inflammation, oxidative stress, autonomic nervous system activation, vascular dysfunction, platelet activation, metabolite dysfunction, small molecule RNA regulation, and the cardioprotective occurrence was discussed. Additionally, improved diagnosis such as, the utilized of portable device, and treatment especially with inconsistent results in continuous positive airway pressure and mandibular advancement devices were illustrated in detail. Therefore, further fundamental and clinical research should be carried out for a better understanding the deep interaction between OSA and atherosclerosis, as well as the suggestion of newer diagnostic and treatment options.

[Correlation between transient receptor potential canonical channel with heart and kidney injure of rat model of obstructive sleep apnea hypopnea syndrome]

OBJECTIVE

To investigate the expression of transient receptor potential canonical channels (TRPCs) in the heart and kidney of rat model of obstructive sleep apnea hypopnea syndrome (OSAHS).

METHODS

Eighteen male SD rats were randomly assigned to intermittent hypoxia (IH) group (n=9 ) and control group (n=9). In IH group, rats were placed in a chamber and exposed to intermittent hypoxia for 8h (10AM-6PM) daily. The expression of TRPC-related mRNA and protein in the heart and kidney tissue were detected by qRT-PCR and Western blotting, respectively.

RESULTS

The mRNA expressions of TRPC3/TRPC4/TRPC5 in heart tissues of IH group were increased significantly compared with the control group (all P>0.05); while there were no significant differences in the mRNA expressions of TRPC1/TRPC3/TRPC4/TRPC5/TRPC6/TRPC7 in kidney tissue between two groups (all P<0.05). The mRNA expressions of TRPC4, TRPC5 and TRPC6 in kidney tissues of IH group were lower than that in heart tissues (all P<0.05). The mRNA expression of TRPC7 in kidney tissues of control group was significantly higher than that in heart tissues (P<0.05). The expression of TRPC5 protein in heart tissues of IH group was significantly higher than that in the control group (P<0.05); while there was no significant differences in the expression of TRPC5/TRPC6/TRPC7 protein in kidney tissue between two groups (all P>0.05).

CONCLUSIONS

The IH rat model shows that TRPC5 channel is likely to be involved in the OSAHS induced pathophysiological changes in the myocardium and may become a target to prevent OSAHS related cardiac damage.

Pathophysiological implications of hypoxia in human diseases

Oxygen is essentially required by most eukaryotic organisms as a scavenger to remove harmful electron and hydrogen ions or as a critical substrate to ensure the proper execution of enzymatic reactions. All nucleated cells can sense oxygen concentration and respond to reduced oxygen availability (hypoxia). When oxygen delivery is disrupted or reduced, the organisms will develop numerous adaptive mechanisms to facilitate cells survived in the hypoxic condition. Normally, such hypoxic response will cease when oxygen level is restored. However, the situation becomes complicated if hypoxic stress persists (chronic hypoxia) or cyclic normoxia-hypoxia phenomenon occurs (intermittent hypoxia). A series of chain reaction-like gene expression cascade, termed hypoxia-mediated gene regulatory network, will be initiated under such prolonged or intermittent hypoxic conditions and subsequently leads to alteration of cellular function and/or behaviors. As a result, irreversible processes occur that may cause physiological disorder or even pathological consequences. A growing body of evidence implicates that hypoxia plays critical roles in the pathogenesis of major causes of mortality including cancer, myocardial ischemia, metabolic diseases, and chronic heart and kidney diseases, and in reproductive diseases such as preeclampsia and endometriosis. This review article will summarize current understandings regarding the molecular mechanism of hypoxia in these common and important diseases.

Potential Role of mRNAs and LncRNAs in Chronic Intermittent Hypoxia Exposure-Aggravated Atherosclerosis

Atherosclerosis is the pathological basis of cardiovascular disease. Obstructive sleep apnea (OSA) aggravates atherosclerosis, and chronic intermittent hypoxia (CIH) as a prominent feature of OSA plays an important role during the process of atherosclerosis. The mechanisms of CIH in the development of atherosclerosis remain unclear. In the current study, we used microarray to investigate differentially expressed mRNAs and long non-coding RNAs (lncRNAs) in aorta from five groups of ApoE^–/– mice fed with a high-fat diet and exposed to various conditions: normoxia for 8 weeks, CIH for 8 weeks, normoxia for 12 weeks, CIH for 12 weeks, or CIH for 8 weeks followed by normoxia for 4 weeks. Selected transcripts were validated in aorta tissues and RT-qPCR analysis showed correlation with the microarray data. Gene Ontology analysis and pathway enrichment analysis were performed to explore the mRNA function. Bioinformatic analysis indicated that short-term CIH induced up-regulated mRNAs involved in inflammatory response. Pathway enrichment analysis of lncRNA co-localized mRNAs and lncRNA co-expressed mRNAs were performed to explore lncRNA functions. The up-regulated mRNAs, lncRNA co-localized mRNAs and lncRNA co-expressed mRNAs were significantly associated with protein processing in endoplasmic reticulum pathway in atherosclerotic vascular tissue with long-term CIH exposure, suggesting that differentially expressed mRNAs and lncRNAs play important roles in this pathway. Moreover, a mRNA-lncRNA co-expression network with 380 lncRNAs, 508 mRNAs and 3238 relationships was constructed based on the correlation analysis between the differentially expressed mRNAs and lncRNAs. In summary, our study provided a systematic perspective on the potential function of mRNAs and lncRNAs in CIH-aggravated atherosclerosis, and may provide novel molecular candidates for future investigation on atherosclerosis exposed to CIH.

Combination of Sarsasapogenin and Fluticasone attenuates ovalbumin-induced airway inflammation in a mouse asthma model

Objective: Asthma is a very common airway inflammatory disease for which the existing drug therapy options are insufficient. In this study, we explored the mechanisms underlying the anti-inflammatory potential of Sarsapogenin (SG) and its combination with Fluticasone (FC) in ovalbumin (OVA)-induced allergic asthma in mice.Methods: In a standard experimental model, asthma in mice was sensitized and challenged by OVA. The mice were treated with SG and SG + FC during OVA challenge. At the completion, lung weight, inflammatory cell count in bronchoalveolar lavage fluid (BALF), serum cytokines levels, immunoglobulin E (IgE) levels, lung nitrate/nitrite (NO) levels, and lung tissue oxidative stress biomarkers were determined. Histopathological evaluation of the lung tissue was also performed.Key findings: Treatment of mice with SG and SG + FC combination intensely diminished the trafficking of total and differential inflammatory cells count into BALF. SG and SG + FC administration significantly reduced the production of inflammatory cytokines, serum IgE levels and restoration of antioxidant stress markers. Histopathological analysis of lung samples effectually weakened bronchial inflammation and mucus production in the lung with a significant reduction in inflammation and mucus score.Conclusion: Our study results suggested that SG and SG + FC effectively reduced allergic airway inflammation via inhibiting pro-inflammatory cytokines, NO expressions and oxidative stress parameters. So, it could be used as a therapeutic potential agent for the treatment of asthma by decreasing its dose in combination with FC to avoid the chronic adverse effects of FC.

miRNA-Mediated Suppression of a Cardioprotective Cardiokine as a Novel Mechanism Exacerbating Post-MI Remodeling by Sleep Breathing Disorders

Rationale:

Obstructive sleep apnea-hypopnea syndrome, a sleep breathing disorder in which chronic intermittent hypoxia (CIH) is the primary pathology, is associated with multiple cardiovascular diseases. However, whether and how CIH may affect cardiac remodeling following myocardial infarction (MI) remains unknown.

Objective:

To determine whether CIH exposure at different periods of MI may exacerbate post-MI heart failure and to identify the mechanisms underlying CIH-exacerbated post-MI remodeling.

Methods and Results:

Adult male mice were subjected to MI (4 weeks) with and without CIH (4 or 8 weeks). CIH before MI (CIH+MI) had no significant effect on post-MI remodeling. However, double CIH exposure (CIH+MI+CIH) or CIH only during the MI period (MI+CIH) significantly exacerbated pathological remodeling and reduced survival rate. Mechanistically, CIH activated TGF-β (tumor growth factor-β)/Smad (homologs of both the Drosophila protein MAD and the C. elegans protein SMA) signaling and enhanced cardiac epithelial to mesenchymal transition, markedly increasing post-MI cardiac fibrosis. Transcriptome analysis revealed that, among 15 genes significantly downregulated (MI+CIH versus MI), Ctrp9 (a novel cardioprotective cardiokine) was one of the most significantly inhibited genes. Real-time polymerase chain reaction/Western analysis confirmed that cardiomyocyte CTRP9 expression was significantly reduced in MI+CIH mice. RNA-sequencing, real-time polymerase chain reaction, and dual-luciferase reporter assays identified that microRNA-214-3p is a novel Ctrp9 targeting miRNA. Its upregulation is responsible for Ctrp9 gene suppression in MI+CIH. Finally, AAV9 (adeno-associated virus 9)-mediated cardiac-specific CTRP9 overexpression or rCTRP9 (recombinated CTRP9) administration inhibited TGF-β/Smad and Wnt/β-catenin pathways, attenuated interstitial fibrosis, improved cardiac function, and enhanced survival rate in MI+CIH animals.

Conclusions:

This study provides the first evidence that MI+CIH upregulates miR-214-3p, suppresses cardiac CTRP9 (C1q tumor necrosis factor-related protein-9) expression, and exacerbates cardiac remodeling, suggesting that CTRP9 may be a novel therapeutic target against pathological remodeling in MI patients with obstructive sleep apnea-hypopnea syndrome.

miR-146a-5p Mediates Intermittent Hypoxia-Induced Injury in H9c2 Cells by Targeting XIAP

MicroRNAs (miRNAs) have emerged as key modulators in the pathophysiologic processes of cardiovascular diseases. However, its function in cardiac injury induced by obstructive sleep apnea (OSA) remains unknown. The aim of the current study was to identify the effect and potential molecular mechanism of miR-146a-5p in intermittent hypoxia(IH)- induced myocardial damage. We exposed H9c2 cells to IH condition; the expression levels of miR-146a-5p were detected by RT-qPCR. Cell viability, cell apoptosis, and the expressions of apoptosis-associated proteins were assessed via Cell Counting Kit-8 (CCK-8), flow cytometry, and western blotting, respectively. Target genes of miR-146a-5p were confirmed by dual-luciferase reporter assay. IH remarkably lowered viability but enhanced cell apoptosis. Concomitantly, the miR-146a-5p expression level was increased in H9c2 cells after IH. Subsequent experiments showed that IH-induced injury was alleviated through miR-146a-5p silence. X-linked inhibitor of apoptosis protein (XIAP) was predicted by bioinformatics analysis and further confirmed as a direct target gene of miR-146a-5p. Surprisingly, the effect of miR-146a-5p inhibition under IH may be reversed by downregulating XIAP expression. In conclusion, our results demonstrated that miR-146a-5p could attenuate viability and promote the apoptosis of H9c2 by targeting XIAP, thus aggravating the H9c2 cell injury induced by IH, which could enhance our understanding of the mechanisms for OSA-associated cardiac injury.

Monocytic C-C chemokine receptor 5 expression increases in in vitro intermittent hypoxia condition and in severe obstructive sleep apnea patients

Purpose

Obstructive sleep apnea (OSA) patients have higher risk of cardiovascular disease. C-C chemokine receptor 5 (CCR5), as an important receptor for monocyte recruitment and the initiation of atherosclerosis, was studied under intermittent hypoxia and in OSA patients.

Methods

The expression and function of CCR5 regulated by intermittent hypoxia in monocytic THP-1 cells were investigated in an in vitro intermittent hypoxia culture system. The expression levels of protein and mRNA were analyzed by western blot and RT/real-time PCR analysis. Cell adhesion assay and transwell filter migration assay were carried out to investigate the adhesion and chemotaxis of monocytes. In addition, the mRNA expression of CCR5 in monocytes isolated from peripheral blood of 72 adults was analyzed.

Results

Intermittent hypoxia upregulated the expression of CCR5 in THP-1 cells and enhanced the adhesion and chemotaxis of monocytes to vascular endothelial cells mediated by RANTES. The CCR5 expression induced by intermittent hypoxia was inhibited by inhibitor for p42/44 MAPK. Besides, the expression of CCR5 in monocytes increased along the AHI value especially in severe OSA patients that was statistically significant compared with mild and moderate OSA groups.

Conclusions

This study demonstrated the increased monocytic CCR5 gene expression in patients with severe OSA. Intermittent hypoxia, the characteristic of OSA, induced monocytic CCR5 gene expression and the enhanced RANTES-mediated chemotaxis and adhesion through p42/44 MAPK signal pathways.

Obstructive Sleep Apnea in Children and Adolescents and the Risk of Major Adverse Cardiovascular Events: A Nationwide Cohort Study in Taiwan

STUDY OBJECTIVES

This study has investigated the risk of major adverse cardiovascular events (MACEs), including acute myocardial infarction, coronary artery disease, peripheral artery disease, and acute stroke, among children and adolescents (age younger than 20 years) with obstructive sleep apnea (OSA).

METHODS

In this study, the population-based National Health Insurance Research Database of Taiwan was used to identify patients in whom OSA had been first diagnosed between 2000 and 2015. Children and adolescents with OSA (n = 6,535) were included with 1:3 ratio by age, sex, and index year of control participants without OSA (n = 19,605). The Cox proportional regression model was used to evaluate the risk of MACEs in this cohort study.

RESULTS

After a 15-year follow-up, the incidence rate of MACEs was higher in the OSA cohort when compared with the non-OSA control cohort (15.97 and 8.20 per 100,000 person-years, respectively). After adjusting for covariates, the risk of MACEs among children and adolescents with OSA was still significantly higher (hazard ratio = 2.050; 95% confidence interval = 1.312-3.107; P = .010). No MACEs were found in the children and adolescents with OSA who received continuous airway positive pressure treatment or pharyngeal surgery.

CONCLUSIONS

This study found a significantly higher risk of MACEs in children and adolescents with OSA. These findings strongly suggest that clinicians should provide careful follow-up and medical treatment for children and adolescents with OSA.

Intermittent Hypoxia Composite Abnormal Glucose Metabolism-Mediated Atherosclerosis In Vitro and In Vivo: The Role of SREBP-1

Objective

The aim of this study was to establish a 3T3-L1 adipocyte model and ApoE^−/− mouse model of intermittent hypoxia (IH) composite abnormal glucose metabolism (AGM) in vitro and in vivo and explore their synergistic damage effect leading to atherosclerosis (AS) and the influence of SREBP-1 signaling molecule-related mechanisms.

Methods

Mature 3T3-L1 adipocytes were cultured with complete culture medium containing DEX 1 × 10⁶ mol/L for 96 h to establish an AGM-3T3-L1 adipocyte model. Then, AGM-3T3-L1 adipocytes were treated with IH for 0 cycles, 2 cycles, 4 cycles, 8 cycles, 16 cycles, and 32 cycles and sustained hypoxia (SH). ApoE^−/− mice were treated with high-fat diet and injection of STZ solution to establish an AGM-ApoE^−/− mouse model. A total of 16 AGM-ApoE^−/− mice were randomly and averagely divided into the normoxic control group (NC) and model group (CIH). AGM-ApoE^−/− mice of the CIH group were treated with IH, which meant that the oxygen concentration fell to 10 ± 0.5% in the first 90 seconds of one cycle and then increased to 21 ± 0.5% in the later 90 seconds, continuous for eight hours per day (09 : 00-17 : 00) with a total of eight weeks. Eight C57BL/6J mice were used as the blank control group (Con) which was fed with conventional diet. qPCR and Western blotting were used to detect the expression level of SREBP-1c, FAS, and IRS-1. Oil Red O staining was used to compare the plaque of the aorta among each mouse group.

Results

As a result, within 32 cycles of IH, mRNA and protein expression levels of SREBP-1c and FAS in AGM-3T3-L1 adipocytes were elevated with the increase in IH cycles; the mRNA expression of IRS-1 was decreased after IH 32 cycles and lower than that of the SH group. For the study in vivo, Oil Red O staining showed a more obvious AS aortic plaque in the CIH group. After CIH treatment of 4 w and 8 w, fasting blood glucose (FBG) of the NC group and CIH group was higher than that of the Con group, and the insulin level of the CIH group was higher than that of the Con group after IH treatment of 8 w. The expressions of the IRS-1 mRNA level in the aorta, skeletal muscle, and liver of the CIH group were lower than those in the Con group. The mRNA and protein expression of SREBP-1c and its downstream molecule FAS in the aorta, skeletal muscle, and liver significantly enhanced in the CIH group in contrast with those in the Con group.

Conclusion

The CIH composite AGM could promote the progress of AS, which might be related to the modulation of the expression of SREBP-1-related molecular pathways.

Blocking C/EBP β protects vascular endothelial cells from injury induced by intermittent hypoxia

BACKGROUND

Intermittent hypoxia (IH) can damage endothelial cells and lead to apoptosis in obstructive sleep apnea-hypopnea syndrome (OSAHS). Hypoxia induces apoptosis in endothelial cells via upregulation of endothelin-1 (ET-1) and hypoxia inducible factor-1 alpha (HIF-1α) plays a key role in the hypoxic stress response.

PURPOSE

We investigated an approach to diminish the negative effect of HIF-1α while maintaining its protective effect.

METHODS

Human umbilical vein endothelial cells (HUVECs) were subjected to sustained hypoxia (SH) or IH for 24 h, and the responses of HIF-1α, CCAAT/enhancer binding protein beta (C/EBP β), and endothelin-1 (ET-1) were assessed by western blotting. A luciferase reporter system was employed to verify the potential binding site (transcription factor binding site, TFBS) for C/EBP β in the ET-1 promoter. The specificity of regulation of ET-1 by HIF-1α via C/EBP β was evaluated by a lentiviral system. The effects of silencing of C/EBP β on IH-induced apoptosis, vascular endothelial growth factor (VEGF) protein levels, proliferation, and in vitro tube formation were studied.

RESULTS

We found that IH significantly increased HIF-1α, C/EBP β, and ET-1 in HUVECs. Knockdown of HIF-1α or C/EBP β inhibited the upregulation of ET-1 induced by IH. Blocking C/EBP β impaired IH-induced apoptosis but did not affect VEGF expression, proliferation, or in vitro tube formation. C/EBP β was shown to mediate increased ET-1 transcription by HIF-1α through the TFBS, 5'-GTTGCCTGTTG-3', in ET-1 promoter.

CONCLUSION

Silencing of C/EBP β can suppress apoptosis but does not affect the protective role of HIF-1α in the hypoxic stress response.

Endothelial cell autophagy in chronic intermittent hypoxia is impaired by miRNA-30a-mediated translational control of Beclin-1

Chronic intermittent hypoxia (CIH) in obstructive sleep apnea causes damage of aortic endothelial cells, which predisposes the development of many cardiovascular diseases. Recently, both altered expression of microRNAs (miRNAs) and impaired autophagy were found to be associated with endothelial cell dysfunction in CIH. However, the exact molecular regulatory pathway has not been determined. Here, we address this question. In a mouse model of CIH, we detected significant upregulation of miR-30a, a miRNA that targets 3'-untranslated region of autophagy-associated protein 6 (Beclin-1) messenger RNA (mRNA) for suppressing the protein translation, which subsequently attenuated the endothelial cell autophagy against cell death. Indeed, unlike Beclin-1 mRNA, the Beclin-1 protein in endothelial cells did not increase after CIH. Suppression of miR-30a by expression of antisense of miR-30a significantly increased Beclin-1 levels to enhance endothelial cell autophagy in vitro and in vivo, which improved endothelial cell survival against CIH. Together, these data suggest that endothelial cell autophagy in CIH may be attenuated by miR-30a-mediated translational control of Beclin-1 as an important cause of endothelial cell dysfunction and damage.

The role of NF-κB-mediated JNK pathway in cognitive impairment in a rat model of sleep apnea

Background

The aim of this study is to determine the role of nuclear factor kappa B (NF-κB)-mediated c-Jun N-terminal kinase (JNK) pathway in cognitive impairment induced by chronic intermittent hypoxia (CIH).

Methods

Ninety-six male Sprague-Dawley rats were randomly divided into 8 groups: sham group, sustained hypoxia (SH) group, CIH group, CIH + melatonin group, CIH + vitamin E group, CIH + DMSO group, CIH + BAY 11-7082 group and CIH + normal saline (NS) group. Rats were exposed to normoxia, CIH (21% O₂ for 60 s and 10% O₂ for 60 s, cyclically repeated for 10 h/day) or SH (10% O₂ for 10 h/day) for 14 days. Afterwards, Morris water maze test was conducted, and serum and hippocampus tissues were subjected to molecular biological and biochemical analyses.

Results

Compared with the Sham and SH group, oxidative stress was induced by CIH in rat hippocampus with the high level of malondialdehyde (MDA) and 8-iso-PGF2α and the low level of superoxide dismutase (SOD) and glutathione (GSH). Activated NF-κB and its downstream products including tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and inducible nitric oxide synthase (iNOS) were highly expressed in CIH rats. These changes were attenuated by pretreatment of the rats with melatonin and vitamin E. CIH also resulted in hippocampus neuron apoptosis with increased caspase 3 level, dUIP nick end labeling (TUNEL)-positive neurons number and cognitive impairment verified by prolonged latency and shortened time in the target quadrant in Morris water maze test. JNK and its downstream transcriptional factors including c-Jun, activating transcription factor 2 (ATF2), and JunD were all significantly phosphorylated in CIH rats. However, pretreatment of NF-κB inhibitor BAY 11-7082 inhibited the activation of NF-κB under CIH condition and also significantly reduced the phosphorylation of JNK as well as c-Jun, ATF2, and JunD. Moreover, hippocampus neuron apoptosis and cognitive impairment were significantly improved with the pretreatment of BAY 11-7082 in rats subjected to CIH.

Conclusions

These findings suggest that NF-κB-mediated JNK pathway is at least partially implicated in CIH-induced hippocampus neuron apoptosis and cognitive impairment. Inhibition of NF-κB activation provided a therapeutic potential for cognitive impairment in sleep apnea (SA).

Effects of Antioxidant Tempol on Systematic Inflammation and Endothelial Apoptosis in Emphysematous Rats Exposed to Intermittent Hypoxia

PURPOSE

Obstructive sleep apnea and chronic obstructive pulmonary disease are independent risk factors of cardiovascular disease (CVD), and their coexistence is known as overlap syndrome (OS). Endothelial dysfunction is the initial stage of CVD; however, underlying mechanisms linking OS and CVD are not well understood. The aim of this study was to explore whether OS can lead to more severe inflammation and endothelial apoptosis by promoting endothelial dysfunction, and to assess the intervention effects of antioxidant tempol.

MATERIALS AND METHODS

Male Wistar rats (n=66) were exposed to normal oxygen [normal control (NC) group], intermittent hypoxia (IH group), cigarette smoke (CH group), as well as cigarette smoke and IH (OS group). Tempol intervention was assessed in OS group treated with tempol (OST group) or NaCl (OSN group). After an 8-week challenge, lung tissues, serum, and fresh blood were harvested for analysis of endothelial markers and apoptosis.

RESULTS

The levels of intracellular adhesion molecule-1, vascular cellular adhesion molecule-1, and apoptosis in circulating epithelial cells were the highest in OS group and the lowest in NC group. These levels were all greater in IH group than in CH group, and were lower in OST group than in OS and OSN groups (all p<0.001).

CONCLUSION

Synergistic effects of IH with cigarette smoke-induced emphysema produce a greater inflammatory status and endothelial apoptosis. OS-related inflammation and endothelial cell apoptosis may play important roles in promoting cardiovascular dysfunction, and antioxidant tempol could achieve a partial protective effect.

Sleep apnea, metabolic disease, and the cutting edge of therapy

Obstructive sleep apnea (OSA) is common, and many cross-sectional and longitudinal studies have established OSA as an independent risk factor for the development of a variety of adverse metabolic disease states, including hypertension, insulin resistance, type 2 diabetes, nonalcoholic fatty liver disease, dyslipidemia, and atherosclerosis. Nasal continuous positive airway pressure (CPAP) has long been the mainstay of therapy for OSA, but definitive studies demonstrating the efficacy of CPAP in improving metabolic outcomes, or in reducing incident disease burden, are lacking; moreover, CPAP has variable rates of adherence. Therefore, the future of OSA management, particularly with respect to limiting OSA-related metabolic dysfunction, likely lies in a coming wave of alternative approaches to endophenotyping OSA patients, personalized care, and defining and targeting mechanisms of OSA-induced adverse health outcomes.

Obstructive Sleep Apnea With or Without Excessive Daytime Sleepiness: Clinical and Experimental Data-Driven Phenotyping

Introduction: Obstructive sleep apnea (OSA) is a serious and prevalent medical condition with major consequences for health and safety. Excessive daytime sleepiness (EDS) is a common-but not universal-accompanying symptom. The purpose of this literature analysis is to understand whether the presence/absence of EDS is associated with different physiopathologic, prognostic, and therapeutic outcomes in OSA patients. Methods: Articles in English published in PubMed, Medline, and EMBASE between January 2000 and June 2017, focusing on no-EDS OSA patients, were critically reviewed. Results: A relevant percentage of OSA patients do not complain of EDS. EDS is a significant and independent predictor of incident cardiovascular disease (CVD) and is associated with all-cause mortality and an increased risk of metabolic syndrome and diabetes. Male gender, younger age, high body mass index, are predictors of EDS. The positive effects of nasal continuous positive airway pressure (CPAP) therapy on blood pressure, insulin resistance, fatal and non-fatal CVD, and endothelial dysfunction risk factors have been demonstrated in EDS-OSA patients, but results are inconsistent in no-EDS patients. The most sustainable cause of EDS is nocturnal hypoxemia and alterations of sleep architecture, including sleep fragmentation. These changes are less evident in no-EDS patients that seem less susceptible to the cortical effects of apneas. Conclusions: There is no consensus if we should consider OSA as a single disease with different phenotypes with or without EDS, or if there are different diseases with different genetic/epigenetic determinants, pathogenic mechanisms, prognosis, and treatment.The small number of studies focused on this issue indicates the need for further research in this area. Clinicians must carefully assess the presence or absence of EDS and decide accordingly the treatment. This approach could improve combination therapy targeted to a patient's specific pathology to enhance both efficacy and long-term adherence to OSA treatment and significantly reduce the social, economic, and health negative impact of OSA.

Association of sleep-disordered breathing with severe chronic vascular disease in patients with type 2 diabetes

BACKGROUND

Severe chronic vascular disease (CVD) is a major cause of co-morbidity and mortality in patients with type 2 diabetes (DM2). Sleep-disordered breathing (SDB) has been linked to CVD in the general population due to enhanced sympathetic activation, oxidative stress, endothelial dysfunction, and hypertension; however data for DM2 patients is scarce. Therefore, the aim of the present analysis to assess whether SDB is associated with CVD in patients with DM2, independent of other known associated factors.

METHODS

We analyzed cross-sectional data of 679 patients with DM2 from the DIACORE-SDB sub-study for association of SDB with CVD. SDB was assessed with a validated 2-channel ambulatory monitoring device. CVD was ascertained as a previous diagnosis of peripheral artery disease (PAD), coronary artery disease (CAD), or stroke via medical records and general practitioners.

RESULTS

Of the analyzed 679 patients, 228 (34%) had SDB (respiratory event index [REI] ≥15/hour); and were significantly more often affected by CVD than patients without SDB (38% vs. 23%, p < 0.01; PAD 7% vs. 2%, p = 0.01; CAD 27% vs. 18%, p = 0.01; stroke 11% vs. 6%, p = 0.07). Regression analysis accounting for known modulators of CVD, such as age, body-mass index, systolic blood pressure, duration of DM2, HbA1c, smoking status, and low-density lipoprotein showed that the REI was independently associated with CVD (OR 1.099 per 5 REI points; 95%CI = [1.024, 1.179]).

CONCLUSIONS

In patients with DM2, SDB is significantly associated with CVD, independent of other known modulators of atherosclerosis.

Relationship between obstructive sleep apnoea syndrome and essential hypertension: a dose-response meta-analysis

OBJECTIVE

The objective of this study was to summarize the evidence regarding the relationship between obstructive sleep apnoea syndrome (OSAS) and the risk of essential hypertension.

METHODS

The study was a dose-response meta-analysis of observational studies. The PubMed, Embase, CNKI, VIP and CBM databases were searched to collect relative studies examining the relationship between OSAS and the risk of essential hypertension. Studies were retrieved from database establishment through September 2016, and new literature published between September 2016 and May 2017 was later supplemented. Linear and non-linear dose-response models were used to assess the relationship between apnoea-hypopnea index (AHI), which was used to reflect the severity of OSAS, and the risk of essential hypertension. Stata 13.0 was used for the meta-analysis.

RESULTS

Six prospective cohort studies and one case-control study were included, for a total sample size of 6098. The dose-response meta-analysis showed that a high AHI significantly increased the risk of essential hypertension compared with a low AHI (odds ratio (OR) = 1.77, 95% confidence interval (CI) (1.30, 2.41), p = 0.001). The linear dose-response meta-analysis showed that the risk of essential hypertension increased by 17% for every 10 events/h increase in the AHI (OR = 1.17, 95% CI (1.07, 1.27), p = 0.001), and the results of the non-linear dose-response meta-analysis showed that the risk of essential hypertension increased with increasing AHI value.

CONCLUSION

A potential dose-response relationship exists between the severity of OSAS and the risk of essential hypertension. This relationship should be considered when developing prevention measures for essential hypertension.

Human cytomegalovirus infection and coronary heart disease: a systematic review

Background

Human cytomegalovirus (HCMV) infection is closely associated with coronary heart disease.

Main body of the abstract

In 1987, Adam et al. were the first to report an association between HCMV infection and atherosclerosis (AS), and later, many serum epidemiology and molecular biology studies showed that HCMV-infected endothelial cells play an important role in the development of AS. As patients with HCMV are generally susceptible to coronary heart disease, and with the increasing elderly population, a review of recent studies focusing on the relationships of HCMV infection and coronary heart disease is timely and necessary.

Short conclusion

The role of HCMV infection in the development of AS needs further study, since many remaining issues need to be explored and resolved. For example, whether HCMV promotes the development of coronary AS, and what the independent factors that lead to coronary artery AS by viral infection are. A comprehensive understanding of HCMV infection is needed in order to develop better strategies for preventing AS.

Role of the endogenous cannabinoid receptor 1 in brain injury induced by chronic intermittent hypoxia in rats

PURPOSE

This study investigated the effect of rimonabant, a cannabinoid receptor type 1 antagonist, on calcium/calmodulin- dependent protein kinase II and cannabinoid receptor type 1 in chronic intermittent hypoxia.

MATERIALS AND METHODS

Healthy male rats were divided into control group, intermittent hypoxia group for 4 or 6 weeks, hypoxic intervention group that received rimonabant (1 mg/kg/d) before exposure to hypoxia for 4 or 6 weeks (n = 10/group). Morphological changes and expressions of the two indexes in the cerebral hippocampus cells were determined by haematoxylin-eosin staining and immunohistochemistry, respectively.

RESULTS

In the intermittent hypoxia group at 4 weeks, the hippocampal cells were damaged with sparse cytoplasm and unclear boundaries, which are even worse at 6 weeks. In contrast, the hippocampal cells of the hypoxic intervention group were neatly arranged at 4 weeks. At 6 weeks, cells were larger with scarce cytoplasm and nuclear changes indicative of cell death. Calcium/calmodulin-dependent protein kinase II and cannabinoid receptor type 1 expression in the cerebral hippocampus was elevated in the intermittent hypoxia group at 4 weeks with even greater at 6 weeks. Cannabinoid receptor type 1 expression was reduced in the hypoxic intervention group compared to the intermittent hypoxia group. Correlation analysis revealed significant positive correlation of them in the intermittent hypoxia group.

CONCLUSIONS

Chronic intermittent hypoxia induced structural damage in the hippocampus and increased cannabinoid receptor type 1 and calcium/calmodulin-dependent protein kinase II expression, which may mediate cognitive impairment associated with chronic intermittent hypoxia. Rimonabant had a protective effect against chronic intermittent hypoxia.

Prevalence and Predictors of Sleep Apnea Risk among Ghanaian Stroke Survivors

BACKGROUND AND PURPOSE

Sleep apnea (SA) has emerged as a potent risk factor for stroke recurrence and mortality. The burden of SA among stroke survivors in sub-Saharan Africa where stroke incidence and mortality are escalating is unknown. We sought to assess the prevalence of SA risk and its clinical correlates and predictors among Ghanaian stroke survivors.

METHODS

This cross-sectional study involved 200 consecutive stroke survivors attending a neurology clinic in a tertiary medical center in Kumasi, Ghana. The validated Berlin, STOP-BANG, and Epworth Sleepiness Scale questionnaires were administered to all eligible subjects to assess SA risk and daytime somnolence, and their demographic and clinical information, health-related quality of life, and symptoms of depression were collected using the questionnaires.

RESULTS

The median (interquartile range) age of stroke survivors was 62 (52-72) years and 52.5% were male. Ninety-nine (49.5%) subjects were identified as high risk for SA using the Berlin questionnaire, whereas 26 (13%), 137 (68.5%), and 37 (18.5%) subjects were classified as low, intermediate, and high risk for SA, respectively, using the STOP-BANG questionnaire. Patients at high risk of SA were significantly older, used excess alcohol, and were less able to perform activities of daily living, although their mean National Institutes of Health Stroke Scale scores were significantly lower than those with low risk for SA. None of the stroke survivors had ever been screened for SA.

CONCLUSIONS

One out of every 2 stroke survivors attending a neurology clinic in Ghana is at high risk for undiagnosed SA. Greater regional awareness about SA presence and outcomes among patients and providers is warranted.