Transcriptional responses to intermittent hypoxia

Chronic intermittent hypoxia elicits distinct transcriptomic responses among neurons and oligodendrocytes within the brainstem of mice

Chronic intermittent hypoxia (CIH) is a prevalent condition characterized by recurrent episodes of oxygen deprivation, linked to respiratory and neurological disorders. Prolonged CIH is known to have adverse effects, including endothelial dysfunction, chronic inflammation, oxidative stress, and impaired neuronal function. These factors can contribute to serious comorbidities, including metabolic disorders and cardiovascular diseases. To investigate the molecular impact of CIH, we examined male C57BL/6J mice exposed to CIH for 21 days, comparing with normoxic controls. We used single-nucleus RNA sequencing to comprehensively examine the transcriptomic impact of CIH on key cell classes within the brainstem, specifically excitatory neurons, inhibitory neurons, and oligodendrocytes. These cell classes regulate essential physiological functions, including autonomic tone, cardiovascular control, and respiration. Through analysis of 10,995 nuclei isolated from pontine-medullary tissue, we identified seven major cell classes, further subdivided into 24 clusters. Our findings among these cell classes, revealed significant differential gene expression, underscoring their distinct responses to CIH. Notably, neurons exhibited transcriptional dysregulation of genes associated with synaptic transmission, and structural remodeling. In addition, we found dysregulated genes encoding ion channels and inflammatory response. Concurrently, oligodendrocytes exhibited dysregulated genes associated with oxidative phosphorylation and oxidative stress. Utilizing CellChat network analysis, we uncovered CIH-dependent altered patterns of diffusible intercellular signaling. These insights offer a comprehensive transcriptomic cellular atlas of the pons-medulla and provide a fundamental resource for the analysis of molecular adaptations triggered by CIH.NEW & NOTEWORTHY This study on chronic intermittent hypoxia (CIH) from pons-medulla provides initial insights into the molecular effects on excitatory neurons, inhibitory neurons, and oligodendrocytes, highlighting our unbiased approach, in comparison with earlier studies focusing on single target genes. Our findings reveal that CIH affects cell classes distinctly, and the dysregulated genes in distinct cell classes are associated with synaptic transmission, ion channels, inflammation, oxidative stress, and intercellular signaling, advancing our understanding of CIH-induced molecular responses.

The mechanism of the NFAT transcription factor family involved in oxidative stress response

As a transcriptional activator widely expressed in various tissues, nuclear factor of activated T cells (NFAT) is involved in the regulation of the immune system, the development of the heart and brain systems, and classically mediating pathological processes such as cardiac hypertrophy. Oxidative stress is an imbalance of intracellular redox status, characterized by excessive generation of reactive oxygen species, accompanied by mitochondrial dysfunction, calcium overload, and subsequent lipid peroxidation, inflammation, and apoptosis. Oxidative stress occurs during various pathological processes, such as chronic hypoxia, vascular smooth muscle cell phenotype switching, ischemia-reperfusion, and cardiac remodeling. Calcium overload leads to an increase in intracellular calcium concentration, while NFAT can be activated through calcium-calcineurin, which is also the main regulatory mode of NFAT factors. This review focuses on the effects of NFAT transcription factors on reactive oxygen species production, calcium overload, mitochondrial dysfunction, redox reactions, lipid peroxidation, inflammation, and apoptosis in response to oxidative stress. We hope to provide a reference for the functions and characteristics of NFAT involved in various stages of oxidative stress as well as related potential targets.

The role of lncRNAs in intermittent hypoxia and sleep Apnea: A review of experimental and clinical evidence

In this narrative review, we present a comprehensive assessment on the putative roles of long non-coding RNAs (lncRNAs) in intermittent hypoxia (IH) and sleep apnea. Collectively, the evidence from cell culture, animal, and clinical research studies points to the functional involvement of lncRNAs in the pathogenesis, diagnosis, and potential treatment strategies for this highly prevalent disorder. Further research is clearly warranted to uncover the mechanistic pathways and to exploit the therapeutic potential of lncRNAs, thereby improving the management and outcomes of patients suffering from sleep apnea.

Severity of oxidative stress as a hallmark in COVID-19 patients

INTRODUCTION

Understanding the mechanisms and identifying effective treatments for the COVID-19 outbreak are imperative. Therefore, this study aimed to assess the antioxidant status and oxidative stress parameters as potential pivotal mechanisms in asymptomatic, non-severe, and severe COVID-19 patients.

METHODS

This study is a case-control study that was performed on patients referred to the Persian Gulf Martyrs Hospital of Bushehr University of Medical Sciences, Bushehr, Iran, from May 2021 to September 2021. A total of 600 COVID-19 patients (non-severe and severe group) and 150 healthy volunteers of the same age and sex were selected during the same period. On the first day of hospitalization, 10 ml of venous blood was taken from subjects. Then, hematological, biochemical, serological, antioxidant and oxidative stress parameters were determined.

RESULTS

Our results indicated that ESR, CRP, AST, ALT, and LDH significantly augmented in the severe group as compared to the non-severe and normal groups (P ≤ 0.05). It was observed that the levels of FRAP, G6PD activity, and SOD activity significantly reduced in the non-severe patients in comparison with the severe and normal groups (P ≤ 0.05). We found that MDA content and NO metabolite markedly increased in severe patients as compared to the non-severe group.

CONCLUSIONS

Taken together, it seems that the balance between antioxidants and oxidants was disturbed in COVID-19 patients in favor of oxidant markers. In addition, this situation caused more aggravation in severe patients as compared to the non-severe group.

Pathophysiological mechanisms and therapeutic approaches in obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is a common breathing disorder in sleep in which the airways narrow or collapse during sleep, causing obstructive sleep apnea. The prevalence of OSAS continues to rise worldwide, particularly in middle-aged and elderly individuals. The mechanism of upper airway collapse is incompletely understood but is associated with several factors, including obesity, craniofacial changes, altered muscle function in the upper airway, pharyngeal neuropathy, and fluid shifts to the neck. The main characteristics of OSAS are recurrent pauses in respiration, which lead to intermittent hypoxia (IH) and hypercapnia, accompanied by blood oxygen desaturation and arousal during sleep, which sharply increases the risk of several diseases. This paper first briefly describes the epidemiology, incidence, and pathophysiological mechanisms of OSAS. Next, the alterations in relevant signaling pathways induced by IH are systematically reviewed and discussed. For example, IH can induce gut microbiota (GM) dysbiosis, impair the intestinal barrier, and alter intestinal metabolites. These mechanisms ultimately lead to secondary oxidative stress, systemic inflammation, and sympathetic activation. We then summarize the effects of IH on disease pathogenesis, including cardiocerebrovascular disorders, neurological disorders, metabolic diseases, cancer, reproductive disorders, and COVID-19. Finally, different therapeutic strategies for OSAS caused by different causes are proposed. Multidisciplinary approaches and shared decision-making are necessary for the successful treatment of OSAS in the future, but more randomized controlled trials are needed for further evaluation to define what treatments are best for specific OSAS patients.

Angiotensin converting enzyme 2 gene expression and markers of oxidative stress are correlated with disease severity in patients with COVID-19

BACKGROUND

Oxidative stress is thought to play a significant role in the pathogenesis and severity of COVID-19. Additionally, angiotensin converting enzyme 2 (ACE2) expression may predict the severity and clinical course of COVID-19. Accordingly, the aim of the present study was to evaluate the association of oxidative stress and ACE2 expression with the clinical severity in patients with COVID-19.

METHODS AND RESULTS

The present study comprised 40 patients with COVID-19 and 40 matched healthy controls, recruited between September 2021 and March 2022. ACE 2 expression levels were measured using Hera plus SYBR Green qPCR kits with GAPDH used as an internal control. Serum melatonin (MLT) levels, serum malondialdehyde (MDA) levels, and total antioxidant capacity (TAC) were estimated using ELISA. The correlations between the levels of the studied markers and clinical indicators of disease severity were evaluated. Significantly, lower expression of ACE2 was observed in COVID-19 patients compared to controls. Patients with COVID-19 had lower serum levels of TAC and MLT but higher serum levels of MDA compared to normal controls. Serum MDA levels were correlated with diastolic blood pressure (DBP), Glasgow coma scale (GCS) scores, and serum potassium levels. Serum MLT levels were positively correlated with DBP, mean arterial pressure (MAP), respiratory rate, and serum potassium levels. TAC was correlated with GCS, mean platelet volume, and serum creatinine levels. Serum MLT levels were significantly lower in patients treated with remdesivir and inotropes. Receiver operating characteristic curve analysis demonstrates that all markers had utility in discriminating COVID-19 patients from healthy controls.

CONCLUSIONS

Increased oxidative stress and increased ACE2 expression were correlated with disease severity and poor outcomes in hospitalized patients with COVID-19 in the present study. Melatonin supplementation may provide a utility as an adjuvant therapy in decreasing disease severity and death in COVID-19 patients.

Loss of Blood-Brain Barrier Integrity in an In Vitro Model Subjected to Intermittent Hypoxia: Is Reversion Possible with a HIF-1α Pathway Inhibitor?

Several sleep-related breathing disorders provoke repeated hypoxia stresses, which potentially lead to neurological diseases, such as cognitive impairment. Nevertheless, consequences of repeated intermittent hypoxia on the blood-brain barrier (BBB) are less recognized. This study compared two methods of intermittent hypoxia induction on the cerebral endothelium of the BBB: one using hydralazine and the other using a hypoxia chamber. These cycles were performed on an endothelial cell and astrocyte coculture model. Na-Fl permeability, tight junction protein, and ABC transporters (P-gp and MRP-1) content were evaluated with or without HIF-1 inhibitors YC-1. Our results demonstrated that hydralazine as well as intermittent physical hypoxia progressively altered BBB integrity, as shown by an increase in Na-Fl permeability. This alteration was accompanied by a decrease in concentration of tight junction proteins ZO-1 and claudin-5. In turn, microvascular endothelial cells up-regulated the expression of P-gp and MRP-1. An alteration was also found under hydralazine after the third cycle. On the other hand, the third intermittent hypoxia exposure showed a preservation of BBB characteristics. Furthermore, inhibition of HIF-1α with YC-1 prevented BBB dysfunction after hydralazine treatment. In the case of physical intermittent hypoxia, we observed an incomplete reversion suggesting that other biological mechanisms may be involved in BBB dysfunction. In conclusion, intermittent hypoxia led to an alteration of the BBB model with an adaptation observed after the third cycle.

The role of oxidative stress in the pathogenesis of infections with coronaviruses

Coronaviruses can cause serious respiratory tract infections and may also impact other end organs such as the central nervous system, the lung and the heart. The coronavirus disease 2019 (COVID-19) has had a devastating impact on humanity. Understanding the mechanisms that contribute to the pathogenesis of coronavirus infections, will set the foundation for development of new treatments to attenuate the impact of infections with coronaviruses on host cells and tissues. During infection of host cells, coronaviruses trigger an imbalance between increased production of reactive oxygen species (ROS) and reduced antioxidant host responses that leads to increased redox stress. Subsequently, increased redox stress contributes to reduced antiviral host responses and increased virus-induced inflammation and apoptosis that ultimately drive cell and tissue damage and end organ disease. However, there is limited understanding how different coronaviruses including SARS-CoV-2, manipulate cellular machinery that drives redox responses. This review aims to elucidate the redox mechanisms involved in the replication of coronaviruses and associated inflammation, apoptotic pathways, autoimmunity, vascular dysfunction and tissue damage that collectively contribute to multiorgan damage.

Janus, or the Inevitable Battle Between Too Much and Too Little Oxygen

Significance: Oxygen levels are key regulators of virtually every living mammalian cell, under both physiological and pathological conditions. Starting from embryonic and fetal development, through the growth, onset, and progression of diseases, oxygen is a subtle, although pivotal, mediator of key processes such as differentiation, proliferation, autophagy, necrosis, and apoptosis. Hypoxia-driven modifications of cellular physiology are investigated in depth or for their clinical and translational relevance, especially in the ischemic scenario. Recent Advances: The mild or severe lack of oxygen is, undoubtedly, related to cell death, although abundant evidence points at oscillating oxygen levels, instead of permanent low pO₂, as the most detrimental factor. Different cell types can consume oxygen at different rates and, most interestingly, some cells can shift from low to high consumption according to the metabolic demand. Hence, we can assume that, in the intracellular compartment, oxygen tension varies from low to high levels depending on both supply and consumption. Critical Issues: The positive balance between supply and consumption leads to a pro-oxidative environment, with some cell types facing hypoxia/hyperoxia cycles, whereas some others are under fairly constant oxygen tension. Future Directions: Within this frame, the alterations of oxygen levels (dysoxia) are critical in two paradigmatic organs, the heart and brain, under physiological and pathological conditions and the interactions of oxygen with other physiologically relevant gases, such as nitric oxide, can alternatively contribute to the worsening or protection of ischemic organs. Further, the effects of dysoxia are of pivotal importance for iron metabolism. Antioxid. Redox Signal. 37, 972-989.

COVID-19-Associated Stroke

The COVID-19 pandemic has had significant influences on the incidence of acute cerebrovascular accidents and the structure of mortality. SARS-CoV-2 increases the risks of developing both ischemic and hemorrhagic stroke. The key pathogenetic element underlying the development of cerebral stroke in COVID-19 consists of impairments to the operation of angiotensin 2 receptors, which are accompanied by accumulation of excess quantities of angiotensin 2, endothelial dysfunction, hypercoagulation, overproduction of proinflammatory cytokines, and an oxidative storm. In patients with stroke and COVID-19, lesion severity is associated with dual mechanisms of ischemia – systemic and cerebral. The possibilities of medication-based correction of both systemic impairments associated with coronavirus infection and local impairments due to ischemic or hemorrhagic brain damage, are limited. Substances with antioxidant activity may potentially be effective in patients with stroke and COVID-19. Data from a number of clinical rials indicate that Mexidol significantly improves functional outcomes in ischemic stroke. Use of Mexidol in patients with stroke and COVID-19 is advised.

Mitochondrial Dynamics in SARS-COV2 Spike Protein Treated Human Microglia: Implications for Neuro-COVID

Emerging clinical data from the current COVID-19 pandemic suggests that ~ 40% of COVID-19 patients develop neurological symptoms attributed to viral encephalitis while in COVID long haulers chronic neuro-inflammation and neuronal damage result in a syndrome described as Neuro-COVID. We hypothesize that SAR-COV2 induces mitochondrial dysfunction and activation of the mitochondrial-dependent intrinsic apoptotic pathway, resulting in microglial and neuronal apoptosis. The goal of our study was to determine the effect of SARS-COV2 on mitochondrial biogenesis and to monitor cell apoptosis in human microglia non-invasively in real time using Raman spectroscopy, providing a unique spatio-temporal information on mitochondrial function in live cells. We treated human microglia with SARS-COV2 spike protein and examined the levels of cytokines and reactive oxygen species (ROS) production, determined the effect of SARS-COV2 on mitochondrial biogenesis and examined the changes in molecular composition of phospholipids. Our results show that SARS- COV2 spike protein increases the levels of pro-inflammatory cytokines and ROS production, increases apoptosis and increases the oxygen consumption rate (OCR) in microglial cells. Increases in OCR are indicative of increased ROS production and oxidative stress suggesting that SARS-COV2 induced cell death. Raman spectroscopy yielded significant differences in phospholipids such as Phosphatidylinositol (PI), phosphatidylserine (PS), phosphatidylethanolamine (PE) and phosphatidylcholine (PC), which account for ~ 80% of mitochondrial membrane lipids between SARS-COV2 treated and untreated microglial cells. These data provide important mechanistic insights into SARS-COV2 induced mitochondrial dysfunction which underlies neuropathology associated with Neuro-COVID.

Differential Redox State and Iron Regulation in Chronic Obstructive Pulmonary Disease, Acute Respiratory Distress Syndrome and Coronavirus Disease 2019

In patients affected by Acute Respiratory Distress Syndrome (ARDS), Chronic Obstructive Pulmonary Disease (COPD) and Coronavirus Disease 2019 (COVID-19), unclear mechanisms negatively interfere with the hematopoietic response to hypoxia. Although stimulated by physiological hypoxia, pulmonary hypoxic patients usually develop anemia, which may ultimately complicate the outcome. To characterize this non-adaptive response, we dissected the interplay among the redox state, iron regulation, and inflammation in patients challenged by either acute (ARDS and COVID-19) or chronic (COPD) hypoxia. To this purpose, we evaluated a panel of redox state biomarkers that may integrate the routine iron metabolism assays to monitor the patients’ inflammatory and oxidative state. We measured redox and hematopoietic regulators in 20 ARDS patients, 20 ambulatory COPD patients, 9 COVID-19 ARDS-like patients, and 10 age-matched non-hypoxic healthy volunteers (controls). All the examined pathological conditions induced hypoxia, with ARDS and COVID-19 depressing the hematopoietic response without remarkable effects on erythropoietin. Free iron was higher than the controls in all patients, with higher levels of hepcidin and soluble transferrin receptor in ARDS and COVID-19. All markers of the redox state and antioxidant barrier were overexpressed in ARDS and COVID-19. However, glutathionyl hemoglobin, a candidate marker for the redox imbalance, was especially low in ARDS, despite depressed levels of glutathione being present in all patients. Although iron regulation was dysfunctional in all groups, the depressed antioxidant barrier in ARDS, and to a lesser extent in COVID-19, might induce greater inflammatory responses with consequent anemia.

The comparison of oxidative markers between Covid-19 patients and healthy subjects

Aim and Background

Covid-19 has been as an important human infectious disease that has affected several countries. Cytokine storm has major role is Covid-19 pathogenesis. The association between inflammation and oxidative stress is well stablished. In this article, we aim to assess oxidative stress markers in Covid-19 patients compare to the healthy subjects.

Method

A total of 48 persons (24 with Covid-19 and 24 controls) were evaluated in this research. Serum oxidative stress markers including Malondialdehyde (MDA), total oxidant status (TOS), activity of catalase (CAT) and super oxide dismutase (SOD) were measured alongside routine laboratory tests.

Results

Patients group were divided into ICU and Non-ICU groups. ESR, CRP and serum level of ferritin were significantly higher in case group. Serum level of albumin was significantly lower in Covid-19 patients. Serum MDA and TOS was significantly increased in Covid-19 patients. Also, Covid-19 patients had higher serum activity of CAT and GPX.

Conclusion

Oxidative stress markers are significantly elevated in Covid-19 patients. This may have significant role in mechanism of disease development. In the fight against Covid-19, as a global struggle, all possible treatments demand more attention. So, Covid-19 patients may benefit from strategies for reducing or preventing oxidative stress.

Type 1 Diabetes Mellitus in the SARS-CoV-2 Pandemic: Oxidative Stress as a Major Pathophysiological Mechanism Linked to Adverse Clinical Outcomes

Recent reports have demonstrated the association between type 1 diabetes mellitus (T1DM) and increased morbidity and mortality rates during coronavirus disease (COVID-19) infection, setting a priority of these patients for vaccination. Impaired innate and adaptive immunity observed in T1DM seem to play a major role. Severe, life-threatening COVID-19 disease is characterized by the excessive release of pro-inflammatory cytokines, known as a "cytokine storm". Patients with T1DM present elevated levels of cytokines including interleukin-1a (IL), IL-1β, IL-2, IL-6 and tumor necrosis factor alpha (TNF-α), suggesting the pre-existence of chronic inflammation, which, in turn, has been considered the major risk factor of adverse COVID-19 outcomes in many cohorts. Even more importantly, oxidative stress is a key player in COVID-19 pathogenesis and determines disease severity. It is well-known that extreme glucose excursions, the prominent feature of T1DM, are a potent mediator of oxidative stress through several pathways including the activation of protein kinase C (PKC) and the increased production of advanced glycation end products (AGEs). Additionally, chronic endothelial dysfunction and the hypercoagulant state observed in T1DM, in combination with the direct damage of endothelial cells by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), may result in endothelial and microcirculation impairment, which contribute to the pathogenesis of acute respiratory syndrome and multi-organ failure. The binding of SARS-CoV-2 to angiotensin converting enzyme 2 (ACE2) receptors in pancreatic b-cells permits the direct destruction of b-cells, which contributes to the development of new-onset diabetes and the induction of diabetic ketoacidosis (DKA) in patients with T1DM. Large clinical studies are required to clarify the exact pathways through which T1DM results in worse COVID-19 outcomes.

Evaluation and Management of Adults with Obstructive Sleep Apnea Syndrome

Obstructive sleep apnea syndrome (OSAS) is a common and underdiagnosed medical condition characterized by recurrent sleep-dependent pauses and reductions in airflow. While a narrow, collapsible oropharynx plays a central role in the pathophysiology of OSAS, there are other equally important nonanatomic factors including sleep-stage dependent muscle tone, arousal threshold, and loop gain that drive obstructive apneas and hypopneas. Through mechanisms of intermittent hypoxemia, arousal-related sleep fragmentation, and intrathoracic pressure changes, OSAS impacts multiple organ systems. Risk factors for OSAS include obesity, male sex, age, specific craniofacial features, and ethnicity. The prevalence of OSAS is rising due to increasing obesity rates and improved sensitivity in the tools used for diagnosis. Validated questionnaires have an important but limited role in the identification of patients that would benefit from formal testing for OSA. While an in-laboratory polysomnography remains the gold standard for diagnosis, the widespread availability and accuracy of home sleep apnea testing modalities increase access and ease of OSAS diagnosis for many patients. In adults, the most common treatment involves the application of positive airway pressure (PAP), but compliance continues to be a challenge. Alternative treatments including mandibular advancement device, hypoglossal nerve stimulator, positional therapies, and surgical options coupled with weight loss and exercise offer possibilities of an individualized personal approach to OSAS. Treatment of symptomatic patients with OSAS has been found to be beneficial with regard to sleep-related quality of life, sleepiness, and motor vehicle accidents. The benefit of treating asymptomatic OSA patients, particularly with regard to cardiovascular outcomes, is controversial and more data are needed.

Unlocking mammalian regeneration through hypoxia inducible factor one alpha signaling

Historically, the field of regenerative medicine has aimed to heal damaged tissue through the use of biomaterials scaffolds or delivery of foreign progenitor cells. Despite 30 years of research, however, translation and commercialization of these techniques has been limited. To enable mammalian regeneration, a more practical approach may instead be to develop therapies that evoke endogenous processes reminiscent of those seen in innate regenerators. Recently, investigations into tadpole tail regrowth, zebrafish limb restoration, and the super-healing Murphy Roths Large (MRL) mouse strain, have identified ancient oxygen-sensing pathways as a possible target to achieve this goal. Specifically, upregulation of the transcription factor, hypoxia-inducible factor one alpha (HIF-1α) has been shown to modulate cell metabolism and plasticity, as well as inflammation and tissue remodeling, possibly priming injuries for regeneration. Since HIF-1α signaling is conserved across species, environmental or pharmacological manipulation of oxygen-dependent pathways may elicit a regenerative response in non-healing mammals. In this review, we will explore the emerging role of HIF-1α in mammalian healing and regeneration, as well as attempts to modulate protein stability through hyperbaric oxygen treatment, intermittent hypoxia therapy, and pharmacological targeting. We believe that these therapies could breathe new life into the field of regenerative medicine.

Oral microbiome interactions with gingival gene expression patterns for apoptosis, autophagy and hypoxia pathways in progressing periodontitis

Oral mucosal tissues must react with and respond to microbes comprising the oral microbiome ecology. This study examined the interaction of the microbiome with transcriptomic footprints of apoptosis, autophagy and hypoxia pathways during periodontitis. Adult Macaca mulatta (n = 18; 12-23 years of age) exhibiting a healthy periodontium at baseline were used to induce progressing periodontitis through ligature placement around premolar/molar teeth. Gingival tissue samples collected at baseline, 0·5, 1 and 3 months of disease and at 5 months for disease resolution were analysed via microarray. Bacterial samples were collected at identical sites to the host tissues and analysed using MiSeq. Significant changes in apoptosis and hypoxia gene expression occurred with initiation of disease, while autophagy gene changes generally emerged later in disease progression samples. These interlinked pathways contributing to cellular homeostasis showed significant correlations between altered gene expression profiles in apoptosis, autophagy and hypoxia with groups of genes correlated in different directions across health and disease samples. Bacterial complexes were identified that correlated significantly with profiles of host genes in health, disease and resolution for each pathway. These relationships were more robust in health and resolution samples, with less bacterial complex diversity during disease. Using these pathways as cellular responses to stress in the local periodontal environment, the data are consistent with the concept of dysbiosis at the functional genomics level. It appears that the same bacteria in a healthy microbiome may be interfacing with host cells differently than in a disease lesion site and contributing to the tissue destructive processes.

The incidence of malignant brain tumors is increased in patients with obstructive sleep apnea: A national health insurance survey

The association between obstructive sleep apnea (OSA) and malignant brain tumors has yet to be fully investigated. Therefore, the purpose of this study was to elucidate the effect of OSA on brain tumor incidence based on the Korea National Health Insurance Service (KNHIS) dataset. The KNHIS data between 2007 and 2014 were analyzed, and the primary endpoint was newly diagnosed malignant brain tumor. A total of 198,574 subjects aged ≥ 20 years with newly diagnosed OSA were enrolled in the study, and 992,870 individuals were selected as a control group based on propensity score matching (PSM) by gender and age. The average follow-up duration was 4.8 ± 2.3 years. The hazard ratios (HRs) for brain tumor for patients with OSA were 1.78 (95% confidence interval [CI]: 1.42-2.21) in Model 1 (not adjusted with any covariate) and 1.67 (95% CI: 1.34-2.09) in Model 2 (adjusted for income level, diabetes, hypertension, dyslipidemia, and COPD). In subgroup analysis by gender, the odds ratios (OR) of OSA were 1.82 (95% CI: 1.41-2.33) in men and 1.26 (95% CI: 0.74-2.03) in women. The ORs were 1.97 (95% CI: 1.15-3.24) in the older (age ≥ 65 years) group, 1.66 (95% CI: 1.25-2.17) in the middle-aged (40 ≤ age < 65 years) group, and 1.41 (0.78-2.44) in the young (20 ≤ age < 40 years) group. In conclusion, OSA may increase the incidence of brain tumors.

SARS-CoV-2 infection pathogenesis is related to oxidative stress as a response to aggression

Since the WHO declared COVID-19 a pandemic, a great effort has been made to understand this serious disease. Thousands of studies are being devoted to understanding its epidemiology, its molecular characteristics, its mechanisms, and the clinical evolution of this viral infection. However, little has been published on its pathogenesis and the host response mechanisms in the progress of the disease. Therefore, we propose a hypothesis based on strong scientific documentation, associating oxidative stress with changes found in patients with COVID-19, such as its participation in the amplification and perpetuation of the cytokine storm, coagulopathy, and cell hypoxia. Finally, we suggest a therapeutic strategy to reduce oxidative stress using antioxidants, NF-κB inhibitors, Nrf2 activators, and iron complexing agents. We believe that this hypothesis can guide new studies and therapeutic strategies on this topic.

Chinese Herbs Medicine Huatan Huoxue Prescription for obstructive sleep apnea hypopnea syndrome as complementary therapy: A protocol for a systematic review and meta-analysis

OBJECTIVE

The aim of this systematic review and meta-analysis is to assess effectiveness and safety of Chinese Herbs Medicine Huatan Huoxue Prescription (HTHXP) as complementary therapy in treating bronchiectasis.

METHODS

The following databases will be searched: Embase, Cochrane, PubMed, China National Knowledge Infrastructure, Wan Fang, and VIP database from their inception to April 1, 2020. We performed and completed meta-analysis and methodologic evaluation by Review Manager 5.3.3 and statas 12.0 software. Study selection, data extraction, quality assessment, and assessment of risk bias will be performed by 2 reviewers independently. Odds ratios and correlative 95% confidence intervals will be calculated to present the association between the HTHXP and western medicine treatment using Review Manager version 5.3 when there is sufficient available data.

RESULTS

The results will be disseminated through a peer-reviewed journal publication.

CONCLUSION

These systematic review findings will summarize up-to-date evidence for that HTHXP is more effective and safe as adjunctive treatment for patients with bronchiectasis.

ETHICS AND DISSEMINATION

Ethics approval and patient consent are not required as this study is a systematic review based on published articles.

PROSPERO REGISTRATION NUMBER

INPLASY202050079.

Acute pulmonary embolism in patients with obstructive sleep apnea: frequency, hospital outcomes, and recurrence

STUDY OBJECTIVES

The objectives of this study were to assess the effect of obstructive sleep apnea (OSA) on the risk of acute pulmonary embolism (PE), hospital outcomes including mortality, and PE recurrence.

METHODS

We retrospectively enrolled adult patients, admitted to Mayo Clinic Hospital in Rochester, Minnesota, within a 5-year period (2009-2013). We compared frequency of PE, hospital mortality, and secondary outcomes in patients with OSA versus patients without OSA. We assessed risk of PE recurrence in relation to compliance with OSA therapy.

RESULTS

Of 25,038 patients, 3,184 (13%) had OSA and 283 (1.1%) experienced PE. Frequency of PE in patients with and without OSA was 2.4% versus 0.9% (odds ratio [OR], 2.51; 95% confidence interval [CI], 1.9-3.3; P < .001). OSA was independently associated with increased risk of PE after adjusting for demographics and comorbidities (OR, 1.44; 95% CI, 1.07-1.9; P = .017). Adjusted hospital mortality was increased in patients with PE (OR, 2.88; 95% CI, 1.7-4.9; P < .001) but not in patients with OSA (OR, 0.98; 95% CI, 0.7-1.4, P = .92). OSA was not a significant determining factor for mortality in patients who experienced a PE (OR, 0.56; 95% CI, 0.1.1-2.78; P = .47), adjusting for demographics, PE severity, and Charlson comorbidity index. Adjusted risk of PE recurrence was greater in patients with OSA compared with patients without OSA (OR, 2.21; 95% CI, 1.05-4.68; P < .04). The patients compliant with OSA therapy had a lower rate of PE recurrence (16% vs 32%; P = not significant).

CONCLUSIONS

Although OSA significantly increases risk of acute PE occurrence and recurrences, related hospital mortality was not greater in patients with OSA compared with those without OSA. OSA therapy might have a modifying effect on PE recurrence.

Multi-omic analysis of the effects of low frequency ventilation during cardiopulmonary bypass surgery

BACKGROUND

Heart surgery with cardio-pulmonary bypass (CPB) is associated with lung ischemia leading to injury and inflammation. It has been suggested this is a result of the lungs being kept deflated throughout the duration of CPB. Low frequency ventilation (LFV) during CPB has been proposed to reduce lung dysfunction.

METHODS

We used a semi-biased multi-omic approach to analyse lung biopsies taken before and after CPB from 37 patients undergoing coronary artery bypass surgery randomised to both lungs left collapsed or using LFV for the duration of CPB. We also examined inflammatory and oxidative stress markers from blood samples from the same patients.

RESULTS

30 genes were induced when the lungs were left collapsed and 80 by LFV. Post-surgery 26 genes were significantly higher in the LFV vs. lungs left collapsed, including genes associated with inflammation (e.g. IL6 and IL8) and hypoxia/ischemia (e.g. HIF1A, IER3 and FOS). Relatively few changes in protein levels were detected, perhaps reflecting the early time point or the importance of post-translational modifications. However, pathway analysis of proteomic data indicated that LFV was associated with increased "cellular component morphogenesis" and a decrease in "blood circulation". Lipidomic analysis did not identify any lipids significantly altered by either intervention.

DISCUSSION

Taken together these data indicate the keeping both lungs collapsed during CPB significantly induces lung damage, oxidative stress and inflammation. LFV during CPB increases these deleterious effects, potentially through prolonged surgery time, further decreasing blood flow to the lungs and enhancing hypoxia/ischemia.

Iron and Sphingolipids as Common Players of (Mal)Adaptation to Hypoxia in Pulmonary Diseases

Hypoxia, or lack of oxygen, can occur in both physiological (high altitude) and pathological conditions (respiratory diseases). In this narrative review, we introduce high altitude pulmonary edema (HAPE), acute respiratory distress syndrome (ARDS), Chronic Obstructive Pulmonary Disease (COPD), and Cystic Fibrosis (CF) as examples of maladaptation to hypoxia, and highlight some of the potential mechanisms influencing the prognosis of the affected patients. Among the specific pathways modulated in response to hypoxia, iron metabolism has been widely explored in recent years. Recent evidence emphasizes hepcidin as highly involved in the compensatory response to hypoxia in healthy subjects. A less investigated field in the adaptation to hypoxia is the sphingolipid (SPL) metabolism, especially through Ceramide and sphingosine 1 phosphate. Both individually and in concert, iron and SPL are active players of the (mal)adaptation to physiological hypoxia, which can result in the pathological HAPE. Our aim is to identify some pathways and/or markers involved in the physiological adaptation to low atmospheric pressures (high altitudes) that could be involved in pathological adaptation to hypoxia as it occurs in pulmonary inflammatory diseases. Hepcidin, Cer, S1P, and their interplay in hypoxia are raising growing interest both as prognostic factors and therapeutical targets.

Effect of Hypoxia-Induced MicroRNA-210 Expression on Cardiovascular Disease and the Underlying Mechanism

Cardiovascular diseases have high morbidity and mortality rates worldwide, and their treatment and prevention are challenging. MicroRNAs are a series of noncoding RNAs with highly conserved sequences and regulate gene expression by inhibiting mRNA transcription or degrading targeting proteins. MicroRNA-210 is significantly upregulated during hypoxia and plays a protective role by inhibiting apoptosis and regulating cell proliferation, differentiation, migration, mitochondrial metabolism, and angiogenesis in hypoxic cells. MicroRNA-210 expression is altered in cardiovascular diseases such as atherosclerosis, acute myocardial infarction, preeclampsia, aortic stenosis, and heart failure, and overexpression of microRNA-210 in some of these diseases exerts protective effects on target organs. Furthermore, chronically upregulated miR-210 potentially plays a marked pathogenic role in specific situations. This review primarily focuses on the upstream pathways, downstream targets, clinical progress in cardiovascular disease, and potential applications of microRNA-210.

Translating the Hypoxic Response-the Role of HIF Protein Translation in the Cellular Response to Low Oxygen

Hypoxia-Inducible Factors (HIFs) play essential roles in the physiological response to low oxygen in all multicellular organisms, while their deregulation is associated with human diseases. HIF levels and activity are primarily controlled by the availability of the oxygen-sensitive HIFα subunits, which is mediated by rapid alterations to the rates of HIFα protein production and degradation. While the pathways that control HIFα degradation are understood in great detail, much less is known about the targeted control of HIFα protein synthesis and what role this has in controlling HIF activity during the hypoxic response. This review will focus on the signalling pathways and RNA binding proteins that modulate HIFα mRNA half-life and/or translation rate, and their contribution to hypoxia-associated diseases.

Neural Activation of Molecular Circuitry in Intermittent Hypoxia

People living at sea level experience intermittent hypoxia (IH) as a consequence of sleep apnea, which is a highly prevalent respiratory disorder. Sleep apnea patients and rodents exposed to IH exhibit autonomic dysfunction manifested as increased sympathetic nerve activity and hypertension. This article highlights physiologic basis of autonomic disturbances by IH, which involves abnormal activation of the carotid body (CB) chemo reflex by reactive oxygen species (ROS).We further evaluate major molecular mechanisms underlying IH-induced ROS generation including transcriptional activation of genes encoding pro-oxidant enzymes by hypoxia-inducible factor (HIF)-1 and transcriptional repression of anti-oxidant enzyme genes by DNA methylation. Lastly, evidence is presented for CB neural activity as a major regulator of HIF-1 activation and DNA methylation by IH in the chemo reflex pathway.

Advances in cellular and integrative control of oxygen homeostasis within the central nervous system

Mammals must continuously regulate the levels of O2 and CO2 , which is particularly important for the brain. Failure to maintain adequate O2 /CO2 homeostasis has been associated with numerous disorders including sleep apnoea, Rett syndrome and sudden infant death syndrome. But, O2 /CO2 homeostasis poses major regulatory challenges, even in the healthy brain. Neuronal activities change in a differentiated, spatially and temporally complex manner, which is reflected in equally complex changes in O2 demand. This raises important questions: is oxygen sensing an emergent property, locally generated within all active neuronal networks, and/or the property of specialized O2 -sensitive CNS regions? Increasing evidence suggests that the regulation of the brain's redox state involves properties that are intrinsic to many networks, but that specialized regions in the brainstem orchestrate the integrated control of respiratory and cardiovascular functions. Although the levels of O2 in arterial blood and the CNS are very different, neuro-glial interactions and purinergic signalling are critical for both peripheral and CNS chemosensation. Indeed, the specificity of neuroglial interactions seems to determine the differential responses to O2 , CO2 and the changes in pH.

Models of intermittent hypoxia and obstructive sleep apnea: molecular pathways and their contribution to cancer

Obstructive sleep apnea (OSA) is common and linked to a variety of poor health outcomes. A key modulator of this disease is nocturnal intermittent hypoxia. There is striking epidemiological evidence that patients with OSA have higher rates of cancer and cancer mortality. Small-animal models demonstrate an important role for systemic intermittent hypoxia in tumor growth and metastasis, yet the underlying mechanisms are poorly understood. Emerging data indicate that intermittent hypoxia activates the hypoxic response and inflammatory pathways in a manner distinct from chronic hypoxia. However, there is significant heterogeneity in published methods for modeling hypoxic conditions, which are often lacking in physiological relevance. This is particularly important for studying key transcriptional mediators of the hypoxic and inflammatory responses such as hypoxia-inducible factor (HIF) and NF-κB. The relationship between HIF, the molecular clock, and circadian rhythm may also contribute to cancer risk in OSA. Building accurate in vitro models of intermittent hypoxia reflective of OSA is challenging but necessary to better elucidate underlying molecular pathways.

Hypoxia-inducible transcription factors, HIF1A and HIF2A, increase in aging mucosal tissues

Hypoxia (i.e. oxygen deprivation) activates the hypoxia-signalling pathway, primarily via hypoxia-inducible transcription factors (HIF) for numerous target genes, which mediate angiogenesis, metabolism and coagulation, among other processes to try to replenish tissues with blood and oxygen. Hypoxia signalling dysregulation also commonly occurs during chronic inflammation. We sampled gingival tissues from rhesus monkeys (Macaca mulatta; 3-25 years old) and total RNA was isolated for microarray analysis. HIF1A, HIF1B and HIF2A were significantly different in healthy aged tissues, and both HIF1A and HIF3A were positively correlated with aging. Beyond these transcription factor alterations, analysis of patterns of gene expression involved in hypoxic changes in tissues showed specific increases in metabolic pathway hypoxia-inducible genes, whereas angiogenesis pathway gene changes were more variable in healthy aging tissues across the animals. With periodontitis, aging tissues showed decreases in metabolic gene expression related to carbohydrate/lipid utilization (GBE1, PGAP1, TPI1), energy metabolism and cell cycle regulation (IER3, CCNG2, PER1), with up-regulation of transcription genes and cellular proliferation genes (FOS, EGR1, MET, JMJD6) that are hypoxia-inducible. The potential clinical implications of these results are related to the epidemiological findings of increased susceptibility and expression of periodontitis with aging. More specifically the findings describe that hypoxic stress may exist in aging gingival tissues before documentation of clinical changes of periodontitis and, so, may provide an explanatory molecular risk factor for an elevated capacity of the tissues to express destructive processes in response to changes in the microbial biofilms characteristic of a more pathogenic microbial challenge.

Inhibition of microRNA-218 reduces HIF-1α by targeting on Robo1 in mice aortic endothelial cells under intermittent hypoxia

OBJECTIVE

To investigate the effects of miR-218 on expression of hypoxia-inducible factors 1α (HIF-1α), vascular endothelial growth factor (VEGF) and cell apoptosis in normal mice aortic endothelial cells under intermittent hypoxia (IH) condition.

METHODS

Anti-miR-218 inhibitor, miR-negative control and miR-218 mimic were used to tranfect the cells in different groups under IH condition. Both RT-PCR and Western blot were used to determine the expressions of HIF-1α and VEGF. Akt, p-Akt and cell apoptosis related proteins bcl-2, bax and caspase-3 and roundabout 1 (Robo1) were measured using Western blot. Cell apoptosis was evaluated by flow cytometry. Statistical analysis was performed using SPSS 18.0.

RESULTS

Expression of miR-218 was significantly up-regulated in the IH group and was significantly inhibited when cells were transfected with miR-218 inhibitor. Down regulation of miR-218 could reduce the expression of HIF-1α and VEGF under intermittent hypoxia condition. In cells transfected with miR-218 mimic, expression of HIF-1α and VEGF significantly increased compared with the control. However, when treated with LY294002, the expression of HIF-1α and VEGF both decreased. Apoptosis assay showed that down regulation of miR-218 could inhibit intermittent hypoxia induced cell apoptosis, decrease expression of caspase-3 and bax and increase expression of bcl-2 under intermittent hypoxia condition. At last, silencing Robo1 could significantly enhance the expression of HIF-1α under IH condition.

CONCLUSION

Inhibition of miR-218 could reduce the expression of HIF-1α and protect against IH-induced apoptosis in mice aortic endothelial cells. The effects were associated with PI3K/AKT pathway and might through targeting of Robo1.

Vascular peroxidase 1 mediates hypoxia-induced pulmonary artery smooth muscle cell proliferation, apoptosis resistance and migration

Aims

Reactive oxygen species (ROS) play essential roles in the pulmonary vascular remodelling associated with hypoxia-induced pulmonary hypertension (PH). Vascular peroxidase 1 (VPO1) is a newly identified haeme-containing peroxidase that accelerates oxidative stress development in the vasculature. This study aimed to determine the potential role of VPO1 in hypoxia-induced PH-related vascular remodelling.

Methods and results

The vascular morphology and VPO1 expression were assessed in the pulmonary arteries of Sprague–Dawley (SD) rats. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4 (NOX4) and VPO1 expression and HOCl production were significantly increased in hypoxic rats, which also exhibited obvious vascular remodelling. Furthermore, a hypoxia-induced PH model was generated by exposing primary rat pulmonary artery smooth muscle cells (PASMCs) to hypoxic conditions (3% O2, 48 h), which significantly increased the expression of NOX4 and VPO1 and the production of HOCl. These hypoxic changes were accompanied by enhanced proliferation, apoptosis resistance, and migration. In PASMCs, hypoxia-induced changes, including effects on the expression of cell cycle regulators (cyclin B1 and cyclin D1), apoptosis-related proteins (bax, bcl-2, and cleaved caspase-3), migration promoters (matrix metalloproteinases 2 and 9), and NF-κB expression, as well as the production of HOCl, were all inhibited by silencing VPO1 with small interfering RNAs. Moreover, treatment with HOCl under hypoxic conditions upregulated NF-κB expression and enhanced proliferation, apoptosis resistance, and migration in PASMCs, whereas BAY 11-7082 (an inhibitor of NF-κB) significantly inhibited these effects.

Conclusion

Collectively, these results demonstrate that VPO1 promotes hypoxia-induced proliferation, apoptosis resistance, and migration in PASMCs via the NOX4/VPO1/HOCl/NF-κB signalling pathway.

Optimizing stem cells for cardiac repair: Current status and new frontiers in regenerative cardiology

Cell therapy has the potential to improve healing of ischemic heart, repopulate injured myocardium and restore cardiac function. The tremendous hope and potential of stem cell therapy is well understood, yet recent trials involving cell therapy for cardiovascular diseases have yielded mixed results with inconsistent data thereby readdressing controversies and unresolved questions regarding stem cell efficacy for ischemic cardiac disease treatment. These controversies are believed to arise by the lack of uniformity of the clinical trial methodologies, uncertainty regarding the underlying reparative mechanisms of stem cells, questions concerning the most appropriate cell population to use, the proper delivery method and timing in relation to the moment of infarction, as well as the poor stem cell survival and engraftment especially in a diseased microenvironment which is collectively acknowledged as a major hindrance to any form of cell therapy. Indeed, the microenvironment of the failing heart exhibits pathological hypoxic, oxidative and inflammatory stressors impairing the survival of transplanted cells. Therefore, in order to observe any significant therapeutic benefit there is a need to increase resilience of stem cells to death in the transplant microenvironment while preserving or better yet improving their reparative functionality. Although stem cell differentiation into cardiomyocytes has been observed in some instance, the prevailing reparative benefits are afforded through paracrine mechanisms that promote angiogenesis, cell survival, transdifferentiate host cells and modulate immune responses. Therefore, to maximize their reparative functionality, ex vivo manipulation of stem cells through physical, genetic and pharmacological means have shown promise to enable cells to thrive in the post-ischemic transplant microenvironment. In the present work, we will overview the current status of stem cell therapy for ischemic heart disease, discuss the most recurring cell populations employed, the mechanisms by which stem cells deliver a therapeutic benefit and strategies that have been used to optimize and increase survival and functionality of stem cells including ex vivo preconditioning with drugs and a novel “pharmaco-optimizer” as well as genetic modifications.

Intermittent hypoxia confers pro-metastatic gene expression selectively through NF-κB in inflammatory breast cancer cells

Inflammatory breast cancer (IBC) is the most aggressive form of breast cancer. Treatment options are limited and the mechanisms underlying its aggressiveness are poorly understood. Intermittent hypoxia (IH) causes oxidative stress and is emerging as important regulator of tumor metastasis. Vessels in IBC tumors have been shown to be immature, which is a primary cause of IH. We therefore investigated the relevance of IH for the modulation of gene expression in IBC cells in order to assess IH as potential regulator of IBC aggressiveness. Gene array analysis of IBC cells following chronic IH (45-60 days) demonstrated increased expression of pro-metastatic genes of the extracellular matrix, such as tenascin-C (TNC; an essential factor of the metastatic niche) and matrix metalloproteinase 9 (MMP9), and of pro-inflammatory processes, such as cyclooxygenase-2 (COX-2). Investigating the oxidative stress-dependent regulation of TNC, we found a gradual sensitivity on mRNA and protein levels. Oxidative stress activated NF-E2-related factor 2 (Nrf2), c-Jun N-terminal kinase (JNK), c-Jun and nuclear factor κB (NF-κB), but TNC upregulation was only dependent on NF-κB activation. Pharmacological inhibition of inhibitor of NF-κB α (IκBα) phosphorylation as well as overexpression of IκBα prevented TNC, MMP9 and COX-2 induction, whereas the pro-inflammatory cytokine interleukin-1β (IL-1β) increased their expression levels. Analysis of the gene array data showed NF-κB binding sites for 64% of all upregulated genes, linking NF-κB with IH-dependent regulation of pro-metastatic gene expression in IBC cells. Our results provide a first link between intermittent hypoxia and pro-metastatic gene expression in IBC cells, revealing a putative novel mechanism for the high metastatic potential of IBC.

Emerging co-morbidities of obstructive sleep apnea: cognition, kidney disease, and cancer

Obstructive sleep apnea (OSA) causes daytime fatigue and sleepiness, and has an established relationship with cardiovascular and metabolic disease. Recent years have seen the emergence of an evidence base linking OSA with an increased risk of degenerative neurological disease and associated cognitive impairment, an accelerated rate of decline in kidney function with an increased risk of clinically significant chronic kidney disease (CKD), and with a significantly higher rate of cancer incidence and death. This review evaluates the evidence base linking OSA with these seemingly unrelated co-morbidities, and explores potential mechanistic links underpinning their development in patients with OSA, including intermittent hypoxia (IH), sleep fragmentation, sympathetic excitation, and immune dysregulation.

Treatment and prevention of inflammatory responses and oxidative stress in patients with obstructive sleep apnea hypopnea syndrome using Chinese herbal medicines

The present study aimed to investigate the therapeutic effects of Chinese herbal medicines for the treatment and prevention of inflammatory responses and oxidative stress in obstructive sleep apnea hypopnea syndrome (OSAHS). A total of 60 patients with OSAHS were randomly divided into two groups (n=30/group): The experimental group, who received the conventional treatment + oral administration of the traditional Chinese herbal formula, Jiawei Di Tan Tang; and the control group, who received the conventional treatment only. OSAHS patients were included in the current study if they presented with snoring and had an apnea-hypopnea index (AHI) of >30 in a polysomnography study, without comorbidities. The therapeutic course lasted 12 weeks in both groups. Alterations to the mean clinical symptom score, Epworth sleepiness scale (ESS) and AHI scores, lowest nocturnal blood oxygen saturation (SaO2) and the serum levels of superoxide dismutase (SOD), malondialdehyde (MDA), interleukin (IL)-6, tumor necrosis factor (TNF)-α and C-reactive protein (CRP) prior to and following treatment were observed. The mean clinical symptom score was significantly decreased in the experimental group post-treatment compared with the control group (P<0.05). In addition, the clinical symptoms in the experimental group were significantly improved following treatment compared with pre-treatment symptoms (P<0.05). Furthermore, the ESS and AHI scores, lowest nocturnal SaO2 and serum levels of SOD, MDA, IL-6, TNF-α and CRP were significantly improved in the experimental group post-treatment compared with the control group (P<0.05). These parameters in the experimental group were also significantly improved post-treatment compared with those pre-treatment (P<0.05). The results of the present study suggested that oral administration of the traditional Chinese herbal formula Jiawei Di Tan Tang was able to attenuate oxidative stress and inflammatory responses in patients with OSAHS, and thus may relieve their clinical symptoms.

Psoriasis and Sleep Apnea: A Danish Nationwide Cohort Study

STUDY OBJECTIVES

Psoriasis and sleep apnea are associated with significant morbidity and mortality. Although both diseases have been linked with systemic inflammation, studies on their potential bidirectional association are lacking. We investigate the potential association between psoriasis and sleep apnea.

METHODS

All Danish citizens age 18 y or older between January 1, 1997 and December 31, 2011 (n = 5,522,190) were linked at individual level in nationwide registries. Incidence rates (IRs) per 10,000 person-years were calculated and incidence rate ratios (IRRs) adjusted for age, sex, socioeconomic status, smoking history, alcohol abuse, medication, and comorbidity were estimated by Poisson regression.

RESULTS

There were 53,290, 6,885, 6,348, and 39,908 incident cases of mild psoriasis, severe psoriasis, psoriatic arthritis, and sleep apnea, respectively. IRRs (95% confidence interval) for sleep apnea were 1.30 (1.17-1.44), 1.65 (1.23-2.22), and 1.75 (1.35-2.26) in subjects with mild and severe psoriasis, and psoriatic arthritis, and IRRs for mild and severe psoriasis, and psoriatic arthritis in sleep apnea without continuous positive airway pressure (CPAP) therapy were 1.62 (1.41-1.86), 2.04 (1.47-2.82), and 1.94 (1.34-2.79), respectively. In patients with sleep apnea and CPAP therapy (i.e., severe sleep apnea) the IRRs were 1.82 (1.43-2.33), 3.27 (2.03-5.27), and 5.59 (3.74-8.37), respectively.

CONCLUSIONS

Psoriasis was associated with increased risk of sleep apnea, and sleep apnea was associated with increased risk of psoriasis. The clinical significance of this bidirectional relationship warrants further study.

Disrupted intestinal structure in a rat model of intermittent hypoxia

Obstructive sleep apnea (OSA) is a chronic condition characterized by chronic intermittent hypoxia (IH) and subsequent reoxygenation (ROX). The gastrointestinal system, which is particularly sensitive to tissue hypoxia and reduced perfusion, is likely to be affected by OSA. A rat model of IH was used to analyze oxidative stress-associated genes and tight junction proteins by reverse transcription‑quantitative polymerase chain reaction. Subsequently, altered morphology of the duodenal mucosa and elevated Chiu scores were observed in the IH‑exposed rats. In addition, IH exposure resulted in upregulation of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits, NADPH oxidase 2 and p22phox, in the small intestine, and upregulation of transcription factors, including hypoxia‑inducible factor-1, nuclear factor‑κB and activator protein-1. Furthermore, the mRNA expression levels of intestinal tight junction (TJ)-related proteins, claudin-1 and claudin-4, were decreased in the IH‑exposed group, as compared with in the control group. In conclusion, the present study demonstrated that OSA, which is characterized by IH and ROX, may lead to disruption of the duodenum. The mechanism underlying the effects of OSA on duodenal morphology may be associated with increased oxidative stress and activation of transcription factors, subsequently inducing intestinal TJ disruption and intestinal injury.

Peripheral chemoreception and arterial pressure responses to intermittent hypoxia

Carotid bodies are the principal peripheral chemoreceptors for detecting changes in arterial blood oxygen levels, and the resulting chemoreflex is a potent regulator of blood pressure. Recurrent apnea with intermittent hypoxia (IH) is a major clinical problem in adult humans and infants born preterm. Adult patients with recurrent apnea exhibit heightened sympathetic nerve activity and hypertension. Adults born preterm are predisposed to early onset of hypertension. Available evidence suggests that carotid body chemoreflex contributes to hypertension caused by IH in both adults and neonates. Experimental models of IH provided important insights into cellular and molecular mechanisms underlying carotid body chemoreflex-mediated hypertension. This article provides a comprehensive appraisal of how IH affects carotid body function, underlying cellular, molecular, and epigenetic mechanisms, and the contribution of chemoreflex to the hypertension.

Cytokine preconditioning of engineered cartilage provides protection against interleukin-1 insult

BACKGROUND

During osteoarthritis and following surgical procedures, the environment of the knee is rich in proinflammatory cytokines such as IL-1. Introduction of tissue-engineered cartilage constructs to a chemically harsh milieu may limit the functionality of the implanted tissue over long periods. A chemical preconditioning scheme (application of low doses of IL-1) was tested as a method to prepare developing engineered tissue to withstand exposure to a higher concentration of the cytokine, known to elicit proteolysis as well as rapid degeneration of cartilage.

METHODS

Using an established juvenile bovine model system, engineered cartilage was preconditioned with low doses of IL-1α (0.1 ng/mL, 0.5 ng/mL, and 1.0 ng/mL) for 7 days before exposure to an insult dose (10 ng/mL). The time frame over which this protection is afforded was investigated by altering the amount of time between preconditioning and insult as well as the time following insult. To explore a potential mechanism for this protection, one set of constructs was preconditioned with CoCl2, a chemical inducer of hypoxia, before exposure to the IL-1α insult. Finally, we examined the translation of this preconditioning method to extend to clinically relevant adult, passaged chondrocytes from a preclinical canine model.

RESULTS

Low doses of IL-1α (0.1 ng/mL and 0.5 ng/mL) protected against subsequent catabolic degradation by cytokine insult, preserving mechanical stiffness and biochemical composition. Regardless of amount of time between preconditioning scheme and insult, protection was afforded. In a similar manner, preconditioning with CoCl2 similarly allowed for mediation of catabolic damage by IL-1α. The effects of preconditioning on clinically relevant adult, passaged chondrocytes from a preclinical canine model followed the same trends with low-dose IL-1β offering variable protection against insult.

CONCLUSIONS

Chemical preconditioning schemes have the ability to protect engineered cartilage constructs from IL-1-induced catabolic degradation, offering potential modalities for therapeutic treatments.

White matter hypoperfusion and damage in dementia: post-mortem assessment

Neuroimaging has revealed a range of white matter abnormalities that are common in dementia, some that predict cognitive decline. The abnormalities may result from structural diseases of the cerebral vasculature, such as arteriolosclerosis and amyloid angiopathy, but can also be caused by nonstructural vascular abnormalities (eg, of vascular contractility or permeability), neurovascular instability or extracranial cardiac or vascular disease. Conventional histopathological assessment of the white matter has tended to conflate morphological vascular abnormalities with changes that reflect altered interstitial fluid dynamics or white matter ischemic damage, even though the latter may be of extracranial or nonstructural etiology. However, histopathology is being supplemented by biochemical approaches, including the measurement of proteins involved in the molecular responses to brain ischemia, myelin proteins differentially susceptible to ischemic damage, vessel-associated proteins that allow rapid measurement of microvessel density, markers of blood-brain barrier dysfunction and axonal injury, and mediators of white matter damage. By combining neuroimaging with histopathology and biochemical analysis, we can provide reproducible, quantitative data on the severity of white matter damage, and information on its etiology and pathogenesis. Together these have the potential to inform and improve treatment, particularly in forms of dementia to which white matter hypoperfusion makes a significant contribution.

Obstructive sleep apnoea syndrome

Obstructive sleep apnoea syndrome (OSAS) is a common clinical condition in which the throat narrows or collapses repeatedly during sleep, causing obstructive sleep apnoea events. The syndrome is particularly prevalent in middle-aged and older adults. The mechanism by which the upper airway collapses is not fully understood but is multifactorial and includes obesity, craniofacial changes, alteration in upper airway muscle function, pharyngeal neuropathy and fluid shift towards the neck. The direct consequences of the collapse are intermittent hypoxia and hypercapnia, recurrent arousals and increase in respiratory efforts, leading to secondary sympathetic activation, oxidative stress and systemic inflammation. Excessive daytime sleepiness is a burden for the majority of patients. OSAS is also associated with cardiovascular co-morbidities, including hypertension, arrhythmias, stroke, coronary heart disease, atherosclerosis and overall increased cardiovascular mortality, as well as metabolic dysfunction. Whether treating sleep apnoea can fully reverse its chronic consequences remains to be established in adequately designed studies. Continuous positive airway pressure (CPAP) is the primary treatment modality in patients with severe OSAS, whereas oral appliances are also widely used in mild to moderate forms. Finally, combining different treatment modalities such as CPAP and weight control is beneficial, but need to be evaluated in randomized controlled trials. For an illustrated summary of this Primer, visit: http://go.nature.com/Lwc6te.

The impact of sleep and hypoxia on the brain: potential mechanisms for the effects of obstructive sleep apnea

PURPOSE OF REVIEW

Obstructive sleep apnea (OSA) is a chronic, highly prevalent, multisystem disease, which is still largely underdiagnosed. Its most prominent risk factors, obesity and older age, are on the rise, and its prevalence is expected to grow further. The last few years have seen an exponential increase in studies to determine the impact of OSA on the central nervous system. OSA-induced brain injury is now a recognized clinical entity, although its possible dual relationship with several other neuropsychiatric and neurodegenerative disorders is debated. The putative neuromechanisms behind some of the effects of OSA on the central nervous system are discussed in this review, focusing on the nocturnal intermittent hypoxia and sleep fragmentation.

RECENT FINDINGS

Recent preclinical and clinical findings suggest that neurogenic ischemic preconditioning occurs in some OSA patients, and that it may partly explain variability in clinical findings to date. However, the distinct parameters of the interplay between ischemic preconditioning, neuroinflammation, sleep fragmentation and cerebrovascular changes in OSA-induced brain injury are still largely unclear, and more research is required.

SUMMARY

Early diagnosis and intervention in patients with OSA is of paramount importance. Future clinical studies should utilize multimodal investigative approaches to enable more reliable referencing for the acuity of the pathological process, as well as its reversibility following the treatment.