Low temperature reduces occludin expression in bronchial epithelial cells: Implications in cold-induced asthma.

BACKGROUND: Cold exposure is a common factor to trigger asthma attacks. However, the underlying mechanism has not been thoroughly elucidated. We aimed to investigate the hypothesis that low temperature reduces occludin expression and compromises epithelial barrier function in airways, which in turn, results in asthma exacerbation. METHODS: We examined occludin expression in human bronchial epithelial cell line (Beas-2B) cells exposed to either 29 °C or 37 °C. The following drugs were administered prior to cold treatment: MG132 (a proteasome inhibitor), cycloheximide (a protein synthesis inhibitor), HC-067047 plus GSK2193874 (transient receptor potential vanilloid 4 [TRPV4] antagonists), or C4-ceramide (a glucocorticoid-inducible kinase [SGK1] activator). siNedd4-2 was transfected into Beas-2B cells to investigate the role that Nedd4-2 plays in mediating occludin instability induced by cold. In animal experiments, we treated ovalbumin (OVA)-induced asthmatic mice with a thermoneutral temperature of 30 °C or cold exposure (10 °C, 6 h/day) for 2 weeks. GSK2193874 or C4-ceramide was administered during the cold treatment. Occludin expression of the lung, pulmonary permeability, serum IgE levels, and lung inflammation were assessed. RESULTS: Low temperature treatment (29 °C) significantly reduced the expression of occludin in Beas-2B cells from 1 to 9 h, which was rescued upon treatment with MG132, HC-067047 plus GSK2193874, C4-ceramide, or Nedd4-2 knockdown. Low temperatures affected occludin stability through SGK1/Nedd4-2-dependent proteolysis. In vivo mice data revealed that cold exposure compromised the airway epithelial barrier function, decreased occludin expression, and exacerbated lung inflammation, which was attenuated by the GSK2193874 or C4-ceramide injection. CONCLUSION: We identified a potential mechanism underlying cold-induced asthma exacerbation involving Nedd4-2-mediated occludin proteolysis and airway epithelial barrier disruption.

Causal Association between Whole-Body Water Mass and Sleep Apnea: A Mendelian Randomization Study.

Rationale: Growing evidence has suggested that body water content plays a critical role in sleep apnea. However, the causal relationship has not been established. Objectives: This study aimed to investigate whether increased whole-body water mass is causally associated with a higher risk of sleep apnea using two-sample Mendelian randomization (MR) analysis. Methods: Body water mass (BWM)-associated genetic instruments were extracted from a genome-wide association study conducted by Neale Lab, which incorporates 331,315 individuals of European ancestry. Genetic variants for sleep apnea were derived from the FinnGen dataset. MR analysis was performed using inverse variance-weighted and weight median methods, respectively. MR-Egger regression and MR-Pleiotropy Residual Sum and Outlier tests were applied to evaluate the directional pleiotropy. In addition, we performed a multivariable MR analysis that includes body mass index, snoring, and waist-to-hip ratio as covariate exposures to address their confounding effects. To elucidate mechanisms of the association between BWM and sleep apnea, we further conducted MR analysis on common edematous diseases. Results: MR estimates showed that per standard deviation increase in BWM led to an increase in the risk of sleep apnea by 49% (odds ratio [OR], 1.490; 95% confidence interval [CI], 1.308-1.696; P = 1.75 × 10-9). The result after MR-Pleiotropy Residual Sum and Outlier correction further supports their causal association (OR, 1.414; 95% CI, 1.253-1.595; P = 1.76 × 10-8). In addition, the multivariable MR analysis indicates a significant causal association between a higher BWM and increased risk of sleep apnea (OR, 1.204; 95% CI, 1.031-1.377; P = 0.036). Genetic predisposition to a higher BWM was also causally related to increased risk of edematous diseases. Conclusions: Our results suggested that increased BWM is a potential risk factor for sleep apnea. Pathologic edema is a possible intermediate factor mediating this causal association.

Inflammaging and Oxidative Stress in Human Diseases: From Molecular Mechanisms to Novel Treatments.

It has been proposed that a chronic state of inflammation correlated with aging known as inflammaging, is implicated in multiple disease states commonly observed in the elderly population. Inflammaging is associated with over-abundance of reactive oxygen species in the cell, which can lead to oxidation and damage of cellular components, increased inflammation, and activation of cell death pathways. This review focuses on inflammaging and its contribution to various age-related diseases such as cardiovascular disease, cancer, neurodegenerative diseases, chronic obstructive pulmonary disease, diabetes, and rheumatoid arthritis. Recently published mechanistic details of the roles of reactive oxygen species in inflammaging and various diseases will also be discussed. Advancements in potential treatments to ameliorate inflammaging, oxidative stress, and consequently, reduce the morbidity of multiple disease states will be explored.

Expression of ICOSL is associated with decreased survival in invasive breast cancer.

BACKGROUND: Inducible co-stimulator (ICOS) is a CD28-related molecule exclusively expressed on activated T cells and plays a critical role in modulating the immune response in breast cancer. The blockage of ICOS pathway has been shown to inhibit the activity of Type 2 T helper cells, thus potentially protecting against cancer growth. The current study aims to investigate the correlation between inducible co-stimulator ligand (ICOSL) expression in tumor tissues and the prognoses of patients with invasive breast cancer. METHODS: Tumor samples from 562 Chinese patients with invasive breast carcinomas were collected between 2003 and 2010. The expression of ICOSL on breast tumor and adjacent non-cancerous tissue was determined via immunohistochemistry. The overall survival (OS) of patients with positive and negative ICOSL expression were described using Kaplan-Meier curves, respectively. Parametric correlation method was used to analyze the correlation between ICOSL expression and other clinicopathological parameters. ICOSL was selected as a dependent variable for multivariate analysis. RESULTS: Positive ICOSL expression was identified on the plasma membrane in both cytoplasm and the nucleus of breast cancer cells. Membrane-expressed ICOSL is determined as an independent prognostic factor for OS in breast cancer but without significantly correlating with other clinicopathologic parameters such as age, menopausal status, depth of invasion, lymph node metastasis status, histologic classification, etc. CONCLUSION: Our study suggests that the up-regulated expression of ICOSL protein in breast tumor cells can be associated with poor prognoses in invasive breast carcinomas.

Correction: Redox correlation in muscle lengthening and immune response in eccentric exercise.

[This corrects the article DOI: 10.1371/journal.pone.0208799.].

Redox correlation in muscle lengthening and immune response in eccentric exercise.

This study was designed to examine the potential involvement of reactive oxygen species in skeletal muscle dysfunction linked with stretching in a mouse model and to explore the effects of combined antioxidant intake on peripheral leukocyte apoptosis following eccentrically-biased downhill runs in human subjects. In the mouse model, diaphragmatic muscle was stretched by 30% of its optimal length, followed by 5-min contraction. Muscle function and extracellular reactive oxygen species release was measured ex vivo. In human models, participants performed two trials of downhill running either with or without antioxidant supplementation, followed by apoptotic assay of inflammatory cells in the blood. The results showed that stretch led to decreased muscle function and prominent ROS increase during muscle contraction. In human models, we observed an elevation in circulating leukocyte apoptosis 24-48 hours following acute downhill runs. However, there is an attenuated leukocyte apoptosis following the second bout of downhill run. Interestingly, the combination of ascorbic acid (vitamin C) and α-tocopherol (vitamin E) supplementation attenuated the decrease in B-cell lymphoma 2 (Bcl-2) at 24 hours following acute downhill running. These data collectively suggest that significant ROS formation can be induced by muscle-lengthening associated with eccentric exercise, which is accompanied by compromised muscle function. The combination of antioxidants supplementation appears to have a protective role via the attenuation of decrease in anti-apoptotic protein.

Role of ROS and Nutritional Antioxidants in Human Diseases.

The overproduction of reactive oxygen species (ROS) has been implicated in the development of various chronic and degenerative diseases such as cancer, respiratory, neurodegenerative, and digestive diseases. Under physiological conditions, the concentrations of ROS are subtlety regulated by antioxidants, which can be either generated endogenously or externally supplemented. A combination of antioxidant-deficiency and malnutrition may render individuals more vulnerable to oxidative stress, thereby increasing the risk of cancer occurrence. In addition, antioxidant defense can be overwhelmed during sustained inflammation such as in chronic obstructive pulmonary diseases, inflammatory bowel disease, and neurodegenerative disorders, cardiovascular diseases, and aging. Certain antioxidant vitamins, such as vitamin D, are essential in regulating biochemical pathways that lead to the proper functioning of the organs. Antioxidant supplementation has been shown to attenuate endogenous antioxidant depletion thus alleviating associated oxidative damage in some clinical research. However, some results indicate that antioxidants exert no favorable effects on disease control. Thus, more studies are warranted to investigate the complicated interactions between ROS and different types of antioxidants for restoration of the redox balance under pathologic conditions. This review highlights the potential roles of ROS and nutritional antioxidants in the pathogenesis of several redox imbalance-related diseases and the attenuation of oxidative stress-induced damages.

Molecular mechanism of bystander effects and related abscopal/cohort effects in cancer therapy.

Cancer cells subjected to ionizing radiation may release signals which can influence nearby non-irradiated cells, termed bystander effects. The transmission of bystander effects among cancer cells involves the activation of inflammatory cytokines, death ligands, and reactive oxygen/nitrogen species. In addition to bystander effects, two other forms of non-target effects (NTEs) have been identified in radiotherapy, as one is called cohort effects and the other is called abscopal effects. Cohort effects represent the phenomenon where irradiated cells can produce signals that reduce the survival of neighboring cells within an irradiated volume. The effects suggest the importance of cellular communication under irradiation with non-uniform dose distribution. In contrast, abscopal effects describe the NTEs that typically occur in non-irradiated cells distant from an irradiated target. These effects can be mediated primarily by immune cells such as T cells. Clinical trials have shown that application of radiation along with immunotherapy may enhance abscopal effects and improve therapeutic efficacy on non-target lesions outside an irradiated field. According to NTEs, cell viability is reduced not only by direct irradiation effects, but also due to signals emitted from nearby irradiated cells. A clinical consideration of NTEs could have a revolutionary impact on current radiotherapy via the establishment of more efficient and less toxic radiobiological models for treatment planning compared to conventional models. Thus, we will review the most updated findings about these effects and outline their mechanisms and potential applications in cancer treatment with a special focus on the brain, lung, and breast cancers.

Interplay between ROS and Antioxidants during Ischemia-Reperfusion Injuries in Cardiac and Skeletal Muscle.

Ischemia reperfusion (IR), present in myocardial infarction or extremity injuries, is a major clinical issue and leads to substantial tissue damage. Molecular mechanisms underlying IR injury in striated muscles involve the production of reactive oxygen species (ROS). Excessive ROS accumulation results in cellular oxidative stress, mitochondrial dysfunction, and initiation of cell death by activation of the mitochondrial permeability transition pore. Elevated ROS levels can also decrease myofibrillar Ca2+ sensitivity, thereby compromising muscle contractile function. Low levels of ROS can act as signaling molecules involved in the protective pathways of ischemic preconditioning (IPC). By scavenging ROS, antioxidant therapies aim to prevent IR injuries with positive treatment outcomes. Novel therapies such as postconditioning and pharmacological interventions that target IPC pathways hold great potential in attenuating IR injuries. Factors such as aging and diabetes could have a significant impact on the severity of IR injuries. The current paper aims to provide a comprehensive review on the multifaceted roles of ROS in IR injuries, with a focus on cardiac and skeletal muscle, as well as recent advancement in ROS-related therapies.

Hypoxic Preconditioning Attenuates Reoxygenation-Induced Skeletal Muscle Dysfunction in Aged Pulmonary TNF-α Overexpressing Mice.

Aim: Skeletal muscle subjected to hypoxia followed by reoxygenation is susceptible to injury and subsequent muscle function decline. This phenomenon can be observed in the diaphragm during strenuous exercise or in pulmonary diseases such as chronic obstructive pulmonary diseases (COPD). Previous studies have shown that PO2 cycling or hypoxic preconditioning (HPC), as it can also be referred to as, protects muscle function via mechanisms involving reactive oxygen species (ROS). However, this HPC protection has not been fully elucidated in aged pulmonary TNF-α overexpressing (Tg+) mice (a COPD-like model). We hypothesize that HPC can exert protection on the diaphragms of Tg+ mice during reoxygenation through pathways involving ROS/phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/extracellular signal regulated kinase (ERK), as well as the downstream activation of mitochondrial ATP-sensitive potassium channel (mitoKATP) and inhibition of mitochondrial permeability transition pore (mPTP). Methods: Isolated Tg+ diaphragm muscle strips were pre-treated with inhibitors for ROS, PI3K, Akt, ERK, or a combination of mitoKATP inhibitor and mPTP opener, respectively, prior to HPC. Another two groups of muscles were treated with either mitoKATP activator or mPTP inhibitor without HPC. Muscles were treated with 30-min hypoxia, followed by 15-min reoxygenation. Data were analyzed by multi-way ANOVA and expressed as means ± SE. Results: Muscle treated with HPC showed improved muscle function during reoxygenation (n = 5, p < 0.01). Inhibition of ROS, PI3K, Akt, or ERK abolished the protective effect of HPC. Simultaneous inhibition of mitoKATP and activation of mPTP also diminished HPC effects. By contrast, either the opening of mitoKATP channel or the closure of mPTP provided a similar protective effect to HPC by alleviating muscle function decline, suggesting that mitochondria play a role in HPC initiation (n = 5; p < 0.05). Conclusion: Hypoxic preconditioning may protect respiratory skeletal muscle function in Tg+ mice during reoxygenation through redox-sensitive signaling cascades and regulations of mitochondrial channels.

Oxidative Stress in Neurodegenerative Diseases: From Molecular Mechanisms to Clinical Applications.

Increasing numbers of individuals, particularly the elderly, suffer from neurodegenerative disorders. These diseases are normally characterized by progressive loss of neuron cells and compromised motor or cognitive function. Previous studies have proposed that the overproduction of reactive oxygen species (ROS) may have complex roles in promoting the disease development. Research has shown that neuron cells are particularly vulnerable to oxidative damage due to their high polyunsaturated fatty acid content in membranes, high oxygen consumption, and weak antioxidant defense. However, the exact molecular pathogenesis of neurodegeneration related to the disturbance of redox balance remains unclear. Novel antioxidants have shown great potential in mediating disease phenotypes and could be an area of interest for further research. In this review, we provide an updated discussion on the roles of ROS in the pathological mechanisms of Alzheimer's disease, Huntington's disease, Parkinson's disease, amyotrophic lateral sclerosis, and spinocerebellar ataxia, as well as a highlight on the antioxidant-based therapies for alleviating disease severity.

Effects of Ionizing Irradiation on Mouse Diaphragmatic Skeletal Muscle.

Undesirable exposure of diaphragm to radiation during thoracic radiation therapy has not been fully considered over the past decades. Our study aims to examine the potential biological effects on diaphragm induced by radiation. One-time ionizing irradiation of 10 Gy was applied either to the diaphragmatic region of mice or to the cultured C2C12 myocytes. Each sample was then assayed for muscle function, oxidative stress, or cell viability on days 1, 3, 5, and 7 after irradiation. Our mouse model shows that radiation significantly reduced muscle function on the 5th and 7th days and increased reactive oxygen species (ROS) formation in the diaphragm tissue from days 3 to 7. Similarly, the myocytes exhibited markedly decreased viability and elevated oxidative stress from days 5 to 7 after radiation. These data together suggested that a single dose of 10-Gy radiation is sufficient to cause acute adverse effects on diaphragmatic muscle function, redox balance, and myocyte survival. Furthermore, using the collected data, we developed a physical model to formularize the correlation between diaphragmatic ROS release and time after irradiation, which can be used to predict the biological effects of radiation with a specific dosage. Our findings highlight the importance of developing protective strategies to attenuate oxidative stress and prevent diaphragm injury during radiotherapy.

MRI in breast cancer radiotherapy in prone and supine positions.

Contemporary radiotherapy (RT) planning utilizes both a computed tomography (CT) scan either in prone or supine position with no breast compression or magnetic resonance imaging (MRI). The application of MRI is limited by image distortion and a lack of electron density information. The standard supine position not only exposes the tumor to RT non-homogenously, it can cause damage to the neighboring benign tissues. Here, we compare the effectiveness of both the prone and supine positions in breast cancer RT and various aspects of breast cancer treatment planning using MRI and CT.

Reactive oxygen species formation and bystander effects in gradient irradiation on human breast cancer cells.

Ionizing radiation (IR) in cancer radiotherapy can induce damage to neighboring cells via non-targeted effects by irradiated cells. These so-called bystander effects remain an area of interest as it may provide enhanced efficacy in killing carcinomas with minimal radiation. It is well known that reactive oxygen species (ROS) are ubiquitous among most biological activities. However, the role of ROS in bystander effects has not been thoroughly elucidated. We hypothesized that gradient irradiation (GI) has enhanced therapeutic effects via the ROS-mediated bystander pathways as compared to uniform irradiation (UI). We evaluated ROS generation, viability, and apoptosis in breast cancer cells (MCF-7) exposed to UI (5 Gy) or GI (8-2 Gy) in radiation fields at 2, 24 and 48 h after IR. We found that extracellular ROS release induced by GI was higher than that by UI at both 24 h (p < 0.001) and 48 h (p < 0.001). More apoptosis and less viability were observed in GI when compared to UI at either 24 h or 48 h after irradiation. The mean effective doses (ED) of GI were ~130% (24 h) and ~48% (48 h) higher than that of UI, respectively. Our results suggest that GI is superior to UI regarding redox mechanisms, ED, and toxic dosage to surrounding tissues.

Historical role of alpha-1-antitrypsin deficiency in respiratory and hepatic complications.

Alpha-1-antitrypsin (AAT) deficiency is a heritable disease that is commonly associated with complications in the respiratory and hepatic systems. AAT acts as a regulatory enzyme that primarily inhibits neutrophil elastase activity thus protecting tissues from proteolytic damage after inflammation. This paper provides a historical review of the discovery, classification, phenotypic expression, and treatment of AAT deficiency. While its pattern of inheritance has been long understood, the underlying mechanism between AAT deficiency and related diseases remains to be elucidated. Most commonly, AAT deficiency is associated with the development of emphysema in the lungs as well as various liver injuries. Cigarette smoke has been shown to be particularly detrimental in AAT deficient individuals during the development of lung disease. Therefore, understanding familial history may be beneficial when educating patients regarding lifestyle choices. While numerous AAT deficient phenotypes exist in the human populations, only specific variants have been proven to markedly predispose individuals to lung and liver disorders. The exact relationship between AAT levels and the aforementioned diseases is an essential area of further research. It is imperative that clinicians and researchers alike strive to standardize diagnostic criteria and develop safe and effective therapies for this genetic disease.