Intermittent hypoxia induces murine macrophage foam cell formation by IKK-β-dependent NF-κB pathway activation

Obstructive sleep apnea hypopnea syndrome and vascular lesions: An update on what we currently know

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is the most prevalent sleep and respiratory disorder. This syndrome can induce severe cardiovascular and cerebrovascular complications, and intermittent hypoxia is a pivotal contributor to this damage. Vascular pathology is closely associated with the impairment of target organs, marking a focal point in current research. Vascular lesions are the fundamental pathophysiological basis of multiorgan ailments and indicate a shared pathogenic mechanism among common cardiovascular and cerebrovascular conditions, suggesting their importance as a public health concern. Increasing evidence shows a strong correlation between OSAHS and vascular lesions. Previous studies predominantly focused on the pathophysiological alterations in OSAHS itself, such as intermittent hypoxia and fragmented sleep, leading to vascular disruptions. This review aims to delve deeper into the vascular lesions affected by OSAHS by examining the microscopic pathophysiological mechanisms involved. Emphasis has been placed on examining how OSAHS induces vascular lesions through disruptions in the endothelial barrier, metabolic dysregulation, cellular phenotype alterations, neuroendocrine irregularities, programmed cell death, vascular inflammation, oxidative stress and epigenetic modifications. This review examines the epidemiology and associated risk factors for OSAHS and vascular diseases and subsequently describes the existing evidence on vascular lesions induced by OSAHS in the cardiovascular, cerebrovascular, retinal, renal and reproductive systems. A detailed account of the current research on the pathophysiological mechanisms mediating vascular lesions caused by OSAHS is provided, culminating in a discussion of research advancements in therapeutic modalities to mitigate OSAHS-related vascular lesions and the implications of these treatment strategies.

The role of microRNAs in pathophysiology and diagnostics of metabolic complications in obstructive sleep apnea patients

Obstructive sleep apnea (OSA) is one of the most common sleep disorders, which is characterized by recurrent apneas and/or hypopneas occurring during sleep due to upper airway obstruction. Among a variety of health consequences, OSA patients are particularly susceptible to developing metabolic complications, such as metabolic syndrome and diabetes mellitus type 2. MicroRNAs (miRNAs) as epigenetic modulators are promising particles in both understanding the pathophysiology of OSA and the prediction of OSA complications. This review describes the role of miRNAs in the development of OSA-associated metabolic complications. Moreover, it summarizes the usefulness of miRNAs as biomarkers in predicting the aforementioned OSA complications.

Anti-inflammatory therapy of atherosclerosis: focusing on IKKβ

Chronic low-grade inflammation has been identified as a major contributor in the development of atherosclerosis. Nuclear Factor-κappa B (NF-κB) is a critical transcription factors family of the inflammatory pathway. As a major catalytic subunit of the IKK complex, IκB kinase β (IKKβ) drives canonical activation of NF-κB and is implicated in the link between inflammation and atherosclerosis, making it a promising therapeutic target. Various natural product derivatives, extracts, and synthetic, show anti-atherogenic potential by inhibiting IKKβ-mediated inflammation. This review focuses on the latest knowledge and current research landscape surrounding anti-atherosclerotic drugs that inhibit IKKβ. There will be more opportunities to fully understand the complex functions of IKKβ in atherogenesis and develop new effective therapies in the future.

Potential Pathophysiological Pathways in the Complex Relationships between OSA and Cancer

Several epidemiological and clinical studies have suggested a relationship between obstructive sleep apnea (OSA) and a higher incidence or severity of cancer. This relationship appears to be dependent on a myriad of factors. These include non-modifiable factors, such as age and gender; and modifiable or preventable factors, such as specific comorbidities (especially obesity), the use of particular treatments, and, above all, the histological type or location of the cancer. Heterogeneity in the relationship between OSA and cancer is also related to the influences of intermittent hypoxemia (a hallmark feature of OSA), among others, on metabolism and the microenvironment of different types of tumoral cells. The hypoxia inducible transcription factor (HIF-1α), a molecule activated and expressed in situations of hypoxemia, seems to be key to enabling a variety of pathophysiological mechanisms that are becoming increasingly better recognized. These mechanisms appear to be operationally involved via alterations in different cellular functions (mainly involving the immune system) and molecular functions, and by inducing modifications in the microbiome. This, in turn, may individually or collectively increase the risk of cancer, which is then, further modulated by the genetic susceptibility of the individual. Here, we provide an updated and brief review of the different pathophysiological pathways that have been identified and could explain the relationship between OSA and cancer. We also identify future challenges that need to be overcome in this intriguing field of research.

Obstructive Sleep Apnea Affects Lacrimal Gland Function

Purpose

To determine the effect of obstructive sleep apnea syndrome (OSA) on lacrimal gland function and its mechanism.

Methods

Male mice aged seven to eight weeks were housed in cages with cyclic intermittent hypoxia to mimic OSA, and the control group was kept in a normal environment. Slit-lamp observation, fluorescein staining, and corneal sensitivity detection are used to assess cornea changes. Tear secretion was detected by phenol red cotton thread, and the pathological changes of lacrimal gland were observed by hematoxylin and eosin staining, oil red O staining, cholesterol and triglyceride kits, immunofluorescence staining, immunohistochemical staining, real-time polymerase chain reaction, transmission electron microscopy, and Western blot.

Results

Studies revealed a decreased tear secretion, corneal epithelial defects and corneal hypersensitivity. Myoepithelial cell damage, abnormal lipid accumulation, reduced cell proliferation, increased apoptosis and inflammatory cell infiltration in the lacrimal gland were also seen. Hifα and NF-κB signaling pathways, moreover, were activated, while Pparα was downregulated, in the lacrimal glands of OSA mice. Fenofibrate treatment significantly alleviated pathological changes of the lacrimal gland induced by OSA.

Conclusion

OSA disturbs the Hifα/Pparα/NF-κB signaling axis, which affects lacrimal gland structure and function and induces dry eye.

Obesity-related kidney disease: Beyond hypertension and insulin-resistance

Chronic kidney disease (CKD) causes considerable morbidity, mortality, and health expenditures worldwide. Obesity is a significant risk factor for CKD development, partially explained by the high prevalence of diabetes mellitus and hypertension in obese patients. However, adipocytes also possess potent endocrine functions, secreting a myriad of cytokines and adipokines that contribute to insulin resistance and induce a chronic low-grade inflammatory state thereby damaging the kidney. CKD development itself is associated with various metabolic alterations that exacerbate adipose tissue dysfunction and insulin resistance. This adipose-renal axis is a major focus of current research, given the rising incidence of CKD and obesity. Cellular senescence is a biologic hallmark of aging, and age is another significant risk factor for obesity and CKD. An elevated senescent cell burden in adipose tissue predicts renal dysfunction in animal models, and senotherapies may alleviate these phenotypes. In this review, we discuss the direct mechanisms by which adipose tissue contributes to CKD development, emphasizing the potential clinical importance of such pathways in augmenting the care of CKD.

Accumulation of LDL/ox-LDL in the necrotic region participates in osteonecrosis of the femoral head: a pathological and in vitro study

Background

Osteonecrosis of the femoral head (ONFH) is a common but intractable disease that appears to involve lipid metabolic disorders. Although numerous studies have demonstrated that high blood levels of low-density lipoprotein (LDL) are closely associated with ONFH, there is limited evidence to explain the pathological role of LDL. Pathological and in vitro studies were performed to investigate the role of disordered metabolism of LDL and oxidized LDL (ox-LDL) in the femoral head in the pathology of ONFH.

Methods

Nineteen femoral head specimens from patients with ONFH were obtained for immunohistochemistry analysis. Murine long-bone osteocyte Y4 cells were used to study the effects of LDL/ox-LDL on cell viability, apoptosis, and metabolism process of LDL/ox-LDL in osteocytes in normoxic and hypoxic environments.

Results

In the pathological specimens, marked accumulation of LDL/ox-LDL was observed in osteocytes/lacunae of necrotic regions compared with healthy regions. In vitro studies showed that ox-LDL, rather than LDL, reduced the viability and enhanced apoptosis of osteocytes. Pathological sections indicated that the accumulation of ox-LDL was significantly associated with impaired blood supply. Exposure to a hypoxic environment appeared to be a key factor leading to LDL/ox-LDL accumulation by enhancing internalisation and oxidation of LDL in osteocytes.

Conclusions

The accumulation of LDL/ox-LDL in the necrotic region may contribute to the pathology of ONFH. These findings could provide new insights into the prevention and treatment of ONFH.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-021-01601-x.

Obstructive Sleep Apnea as an Acceleration Trigger of Cellular Senescence Processes through Telomere Shortening

Obstructive sleep apnea (OSA) is chronic disorder which is characterized by recurrent pauses of breathing during sleep which leads to hypoxia and its two main pathological sequelae: oxidative stress and chronic inflammation. Both are also associated with cellular senescence. As OSA patients present with higher prevalence of age-related disorders, such as atrial hypertension or diabetes mellitus type 2, a relationship between OSA and accelerated aging is observable. Furthermore, it has been established that these OSA are associated with telomere shortening. This process in OSA is likely caused by increased oxidative DNA damage due to increased reactive oxygen species levels, DNA repair disruptions, hypoxia, chronic inflammation, and circadian clock disturbances. The aim of the review is to summarize study outcomes on changes in leukocyte telomere length (LTL) in OSA patients and describe possible molecular mechanisms which connect cellular senescence and the pathophysiology of OSA. The majority of OSA patients are characterized by LTL attrition due to oxidative stress, hypoxia and inflammation, which make a kind of positive feedback loop, and circadian clock disturbance.

Integrating systematic biological and proteomics strategies to explore the pharmacological mechanism of danshen yin modified on atherosclerosis

This research utilized the systematic biological and proteomics strategies to explore the regulatory mechanism of Danshen Yin Modified (DSYM) on atherosclerosis (AS) biological network. The traditional Chinese medicine database and HPLC was used to find the active compounds of DSYM, Pharmmapper database was used to predict potential targets, and OMIM database and GeneCards database were used to collect AS targets. String database was utilized to obtain the other protein of proteomics proteins and the protein-protein interaction (PPI) data of DSYM targets, AS genes, proteomics proteins and other proteins. The Cytoscape 3.7.1 software was utilized to construct and analyse the network. The DAVID database is used to discover the biological processes and signalling pathways that these proteins aggregate. Finally, animal experiments and proteomics analysis were used to further verify the prediction results. The results showed that 140 active compounds, 405 DSYM targets and 590 AS genes were obtained, and 51 differentially expressed proteins were identified in the DSYM-treated ApoE-/- mouse AS model. A total of 4 major networks and a number of their derivative networks were constructed and analysed. The prediction results showed that DSYM can regulate AS-related biological processes and signalling pathways. Animal experiments have also shown that DSYM has a therapeutic effect on ApoE-/-mouse AS model (P < .05). Therefore, this study proposed a new method based on systems biology, proteomics, and experimental pharmacology, and analysed the pharmacological mechanism of DSYM. DSYM may achieve therapeutic effects by regulating AS-related signalling pathways and biological processes found in this research.

Phenotype of ventilatory control in children with moderate to severe persistent asthma and obstructive sleep apnea

STUDY OBJECTIVES

To examine the role of ventilatory control in asthmatic children with obstructive sleep apnea (OSA) and the relationships between measures of ventilatory control, OSA severity, and pulmonary function.

METHODS

Five- to 18-year-old children with persistent asthma and nightly snoring were enrolled in the study. Children had physical examination, pulmonary function test, and polysomnography. Loop and controller gains were derived from 5 min segments which included a sigh during nonrapid eye movement sleep by applying a mathematical model that quantifies ventilatory control from the ensuing responses to the sighs. Plant gain was derived from 5 min segments of spontaneous breathing (i.e. without sighs). Nonparametric statistical tests were used for group comparisons. Cluster analysis was performed using Bayesian profile regression.

RESULTS

One hundred thirty-four children were included in the study, 77 with and 57 without OSA. Plant gain was higher in children with OSA than in those without OSA (p = 0.002). A negative correlation was observed between plant gain and forced expiratory volume in 1 second (p = 0.048) and the ratio of f forced expiratory volume to forced vital capacity (p = 0.02). Plant gain correlated positively with severity of OSA. Cluster analysis demonstrated that children with more severe OSA and abnormal lung function had higher plant gain and a lower controller gain compared with the rest of the population.

CONCLUSIONS

Children with OSA and persistent asthma with abnormal lung function have phenotypic characteristics which consist of diminished capacity of the lungs to maintain blood gas homeostasis reflected by an increase in plant gain and decreased chemoreceptor sensitivity.

Lipocalin-2 exerts pro-atherosclerotic effects as evidenced by in vitro and in vivo experiments

Lipocalin-2 (LCN2), a multiple bioactive hormone particularly expressed in adipose tissue, neutrophils, and macrophages, is known to exhibit anti-microbial effect, increase inflammatory cytokine levels, and maintain glucose homeostasis. Serum LCN2 level is positively correlated with the severity of coronary artery disease. However, it still remains unknown whether LCN2 affects atherogenesis. We assessed the effects of LCN2 on the inflammatory response and monocyte adhesion in human umbilical vein endothelial cells (HUVECs), inflammatory phenotype and foam cell formation in THP1 monocyte-derived macrophages, and migration and proliferation of human aortic smooth muscle cells (HASMCs) in vitro and aortic lesions in Apoe^-/- mice in vivo. LCN2 and its receptor, low-density lipoprotein (LDL)-related protein-2, were expressed in THP1 monocytes, macrophages, HASMCs, and HUVECs. LCN2 significantly enhanced THP1 monocyte adhesion to HUVECs accompanied with upregulation of intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin associated with nuclear factor-κB (NF-κB) upregulation in HUVECs. LCN2 significantly increased HUVEC proliferation and oxidized LDL-induced foam cell formation in THP1 monocyte-derived macrophages. LCN2 significantly increased the inflammatory M1 phenotype associated with NF-κB upregulation during differentiation of THP1 monocytes into macrophages. In HASMCs, LCN2 significantly promoted the migration and collagen-1 expression without inducing proliferation, which are associated with increased protein expression of phosphoinositide 3-kinase and phosphorylation of Akt, extracellular signal-regulated kinase, c-jun-N-terminal kinase, and NF-κB. Chronic LCN2 infusion into Apoe^-/- mice significantly accelerated the development of aortic atherosclerotic lesions, with increased intraplaque monocyte/macrophage infiltration and pentraxin-3 and collagen-1 expressions. Our results suggested that LCN2 accelerates the development of atherosclerosis. Thus, LCN2 could serve as a novel therapeutic target for atherosclerotic diseases.

Intermittent Hypoxia Enhances THP-1 Monocyte Adhesion and Chemotaxis and Promotes M1 Macrophage Polarization via RAGE

Intermittent hypoxia (IH) that resulted from obstructive sleep apnea (OSA) has been found to be a risk factor of coronary artery disease. IH and the receptor for advanced glycation end products (RAGE) expression are known to activate monocyte/macrophage and associated with atherosclerosis development, while their effects on monocyte adhesion, chemotaxis to the endothelium, and macrophage polarization remain unknown. In the present study, RAGE in THP-1 monocytes was inhibited by shRNA lentiviral particles, followed by exposure to IH. Cell adhesion assay, transwell migration assay, and macrophage polarization assays were performed to study the effects of IH and RAGE. The mRNA and protein expression levels were investigated by RT/real-time PCR and western blot analysis, respectively. We found that IH increased RAGE expression and activated NF-кB signalling in THP-1 monocytes. The results also revealed that IH enhanced the MCP-1-mediated THP-1 monocyte adhesion and chemotaxis and promoted macrophage polarization toward a proinflammatory phenotype, which was mediated by RAGE activity. Additionally, inhibition of chemokine receptor type 2 (CCR2) suppressed the IH-induced monocyte adhesion and chemotaxis. These results demonstrated a potential role of monocyte adhesion, chemotaxis, and macrophage polarization in the development cardiovascular diseases induced by IH and identified that RAGE could be a promising therapeutic target to prevent atherosclerosis in patients with OSA.