Co-morbid OSA and insomnia increases depression prevalence and severity in men.

BACKGROUND AND OBJECTIVE: Obstructive sleep apnoea (OSA) and insomnia coexist in clinical populations but prevalence in the community and risk factors remain largely unknown. We examined the prevalence and profile of previously undiagnosed co-morbid OSA and insomnia symptoms (COMISA) in community-dwelling men. METHODS: Men (n = 700, aged 58.5 ± 11.0 (mean ± SD) years) without a prior diagnosis of OSA completed full at-home unattended polysomnography, the Pittsburgh Sleep Quality Index and 36-item short form (SF-36) survey (2007-2012). Insomnia symptoms included difficulty initiating/maintaining sleep in the presence of daytime fatigue (DIMS-F). Depressive symptoms were assessed using the Beck Depression Inventory-1A, Centre for Epidemiological Studies Depression Scale and Patient Health Questionnaire-9 (PHQ-9) (2007-2010). Univariate (χ2 and analysis of variance (ANOVA)) and multiple linear regressions were used to compare data from four groups of individuals: neither disorder; previously undiagnosed OSA (apnoea-hypopnoea index ≥ 10) or DIMS-F alone; and COMISA. RESULTS: COMISA prevalence was 6.7%. Depression prevalence (COMISA, 42.6%; DIMS-F, 21.6%; OSA, 8.4%, χ2 = 71.6, P < 0.00) and symptom scale scores (e.g. PHQ-9 mean ± SD: 16.1 ± 5.5 c.f. DIMS-F: 14.0 ± 4.9, P < 0.01 and OSA: 11.4 ± 3.0, P = 0.01) were highest in men with COMISA. In COMISA, respiratory and arousal indices were similar to those observed in OSA whilst reductions in subjective sleep and day dysfunction scores were similar to DIMS-F. After adjustment, predicted mean depression scores were all higher in DIMS-F and COMISA using linear regression (e.g. PHQ-9 ß (95% CI): DIMS-F: 2.3 (1.2, 3.5); COMISA: 4.1 (3.0, 5.1)). CONCLUSION: Men with COMISA have a greater prevalence, and severity, of depression than men with only one disorder.

Dietary zinc mediates inflammation and protects against wasting and metabolic derangement caused by sustained cigarette smoke exposure in mice.

In mouse asthma models, inflammation can be modulated by zinc (Zn). Given that appetite loss, muscle wasting and poor nutrition are features of chronic obstructive pulmonary disease (COPD) and that poor dietary Zn intake is in itself accompanied by growth retardation and appetite loss, we hypothesised that dietary Zn limitation would not only worsen airway inflammation but also exaggerate metabolic effects of cigarette smoke (CS) exposure in mice. Conversely, Zn supplementation would lessen inflammation. Mice were exposed to CS [2× 2RF, 3×/day; 15 min/cigarette] and fed diets containing 2, 20 or 140 mg/kg Zn ad libitum. Airway cells were collected by bronchoalveolar lavage (BAL). Plasma Zn was measured by fluorometric assay. Inflammatory, metabolic and Zn transport markers were measured by real-time RT-PCR. Mice fed low Zn diets had less plasma labile zinc (0-0.18 µM) than mice fed moderate (0.61-0.98 µM) or high (0.77-1.1 µM) Zn diets (SDs 0.1-0.4, n = 8-10). Smoke exposure increased plasma and BAL labile Zn (1.5-2.5 fold, P < 0.001), bronchoalveolar macrophages (2.0 fold, P < 0.0001) and MT-1 (1.5 fold), MIP-2 (2.3 fold) and MMP-12 (3.5 fold) mRNA. Zn supplementation reduced alveolar macrophage numbers by 62 and 52% in sham and smoke-exposed mice, respectively (Zn effect: P = 0.011). Gastrocnemius, soleus and tibialis anterior muscle mass were affected by both smoke and dietary Zn in the order of 3-7%. The 50-60% reduction in alveolar macrophages in Zn-supplemented mice supports our evolving hypothesis that Zn is an important anti-inflammatory mediator of airway inflammation. Restoring airway Zn levels through dietary supplementation may lessen the severity of lung inflammation when Zn intake is low.

Ultrastructural analysis, zinc transporters, glucose transporters and hormones expression in New world primate (Callithrix jacchus) and human pancreatic islets.

The New world primates (NWP) Callithrix jacchus separated from man approximately 50 million years ago and is a potential alternative small non-human primate model for diabetes research. Ultrastructure, and gene expression of pancreatic islets and the recently described diabetes auto antigenic zinc transporters families in human, NWP and pig pancreas were studied. Morphologically NWP islets were larger than pig islets and similar in size to human islets. NWP islets alpha cells had high dense core surrounded by a limiting membrane, beta cells by the mixed morphology of the granule core, and delta cells by moderate opaque core. Antibody staining for insulin, glucagon, somatostatin and Glucagon-like peptide-1 (GLP-1) showed that the distribution pattern of the different cell types within islets was comparable to pig and human islets. In all three species protein expression of zinc transporter ZnT8 was detected in most of the insulin producing beta cells whereas Zip14 expression was widely expressed in alpha and beta cells. In both human and NWP little or no expression of Glut2 was observed compared to Glut1 and glucokinase at the protein level, however the messenger RNA level of Glut2 was greater than Glut1 and glucokinase. In contrast all three glucose transporters were expressed in pig islets at the protein level. The expression of Zip14 in islets is reported for the first time. In conclusion NWP pancreatic islets express comparable islet cell types and distribution to humans and pigs. Importantly, marmosets have a similar glucose transporter profile to humans, making this non-endangered primate species a useful animal model for pancreatic biology.

Sociodemographic and behavioural correlates of social jetlag in Australian adults: results from the 2016 National Sleep Health Foundation Study.

Social jetlag is a term used to describe misalignment between biological and social time. Measured as the difference in sleep midpoints between work and free days, social jetlag has been associated with unhealthy lifestyle behaviours and adverse health outcomes. This study aimed to identify the prevalence of social jetlag, and its sociodemographic and behavioural correlates in 837 respondents who completed the Sleep Health Foundation Australia 2016 online survey. Binomial logistic regression models determined associations between social jetlag and self-reported lifestyle and work outcomes, excluding night, evening or rotating shift workers. One third (31.1%) of respondents experienced >1h of social jetlag. In analyses adjusted for sociodemographic variables associated with social jetlag (age, marital status, work status and metropolitan living plus the significant interaction term for age by metro living), social jetlag was associated with longer sleep duration on free days (OR = 2.8, CI = 1.9-4.1), evening preference (OR = 2.0, CI = 1.4-2.4), often staying up later than planned on work days (OR 1.9, CI = 1.3-2.9), and having a computer (OR = 1.7, CI = 1.2-2.4) or phone (OR = 1.6, CI = 1.1-2.4) in the bedroom and internet use in the hour before bed (OR = 1.7, CI 1.2-2.5). Almost twice as many working respondents with social jetlag reported going to work when they should have taken sick leave due to their state of health (OR = 1.9, CI = 1.3-3.0). In conclusion, social jetlag is prevalent in the Australian community and associated with bedtime technology use. Work attendance when in poor health is cause for concern in Australian day workers and requires further investigation.

Prevalence and comorbidity of sleep conditions in Australian adults: 2016 Sleep Health Foundation national survey.

OBJECTIVE: To determine the prevalence of sleep conditions (obstructive sleep apnea [OSA], insomnia symptoms, simple snoring, and restless legs) and their associated burden of chronic conditions in a community sample. DESIGN: Cross-sectional national adult online survey. SETTING: Community-based sample. PARTICIPANTS: Australian adults ≥18 years, N = 1011. MEASUREMENTS: A cross-sectional national online survey assessed diagnosed OSA, OSA symptoms, insomnia symptoms, sleep problems, excessive daytime sleepiness (Epworth Sleepiness Scale ≥11), and physician-diagnosed health conditions (heart disease, diabetes, hypertension, reflux disease, lung disease, depression, anxiety/panic disorder, arthritis). Possible undiagnosed OSA was estimated using self-reported frequent loud snoring and witness apneas. International Criteria for Sleep Disorders-3 criteria identified insomnia symptoms. Logistic regression models adjusted for age, sex, obesity, and smoking determined correlates of sleep disorders. RESULTS: Comorbid sleep conditions were common, with 56% of participants demonstrating ≥1 condition. Reporting ≥1 mental health condition (depression and/or anxiety) was independently associated with diagnosed OSA (odds ratio [95% confidence interval {CI}]: 6.6 [3.2-13.6]), undiagnosed OSA (3.2 [1.8-5.8]), simple snoring (2.4 [1.2-4.5]), insomnia symptoms (4.3 [2.5-7.3]), and restless legs (1.9 [1.2-3.1]). Diagnosed OSA was significantly associated with ≥1 cardiometabolic condition (2.9 [1.4-6.0]) and arthritis (3.6 [1.8-7.2]). ESS ≥11 was associated with diagnosed (3.1 [1.4-6.8]) and undiagnosed OSA (6.2 [3.4-11.4]), insomnia symptoms (2.6 [1.4-4.9]), and restless legs (2.3 [1.4-4.0]), and these sleep conditions were also significantly associated with ≥2 diagnosed medical problems. CONCLUSION: Strategies to facilitate the diagnosis and management of often comorbid sleep disorders in primary care are required to reduce the significant sleep-related disparities in cardiometabolic and mental health.

Associations of Undiagnosed Obstructive Sleep Apnea and Excessive Daytime Sleepiness With Depression: An Australian Population Study.

STUDY OBJECTIVES: To determine whether undiagnosed obstructive sleep apnea (OSA) and/or excessive daytime sleepiness are associated with symptomatic depression in Australian men. METHODS: Participants were randomly selected, urban community dwelling men aged 40 to 88 years without a prior diagnosis of OSA. Clinically significant depressive symptoms were assessed using the Beck Depression Inventory-1A or Centre for Epidemiological Studies Depression Scale (2007-2010). A random sample of men (n = 788) undertook full at-home unattended polysomnography (Embletta X100, Broomfield, Colorado, United States) and completed the Epworth Sleepiness Scale questionnaire (2010-2012). RESULTS: Undiagnosed severe obstructive sleep apnea (apnea-hypopnea index ≥ 30 events/h) was associated with depressive symptoms (adjusted odds ratio = 1.98; 95% confidence interval [CI] 1.05-3.73; P = .036). However, a significant interaction was observed between obstructive sleep apnea and excessive daytime sleepiness (P = .03) such that individuals with OSA and excessive daytime sleepiness (Epworth Sleepiness Scale score of 10 or higher) exhibited the strongest associations with depression (mild-moderate apnea: adjusted odd ratio = 3.86; 95% CI 1.87-7.95; severe apnea: adjusted odd ratio = 4.82; 95% CI 1.42-16.35) when compared to individuals without apnea. CONCLUSIONS: Depressive symptoms in men were associated with undiagnosed OSA in the community. It is important that clinicians and primary care practitioners consider screening for depression in men with severe OSA and for OSA in men with depression. Screening for depression should also be considered in men with excessive daytime sleepiness regardless of OSA severity.

Chronic Kidney Disease and Sleep Apnea Association of Kidney Disease With Obstructive Sleep Apnea in a Population Study of Men.

Study Objectives: To determine the relationship between obstructive sleep apnea (OSA) and chronic kidney disease (CKD). Previous population studies of the association are sparse, conflicting and confined largely to studies of administrative data. Methods: Cross-sectional analysis in unselected participants of the Men Androgens Inflammation Lifestyle Environment and Stress (MAILES) study, aged >40 years. Renal data were available for 812 men without a prior OSA diagnosis who underwent full in-home polysomnography (Embletta X100) in 2010-2011. CKD was defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73m2 or eGFR≥60 and albuminuria (albumin-creatinine ratio ≥3.0 mg/mmol). Results: CKD (10.5%, n = 85 [Stage 1-3, 9.7%; Stage 4-5, 0.7%]) of predominantly mild severity showed significant associations with OSA (apnea-hypoapnea index [AHI] ≥ 10): odds ratio (OR) = 1.9, 95% confidence interval (CI): 1.02-3.5; severe OSA (AHI ≥ 30/h): OR = 2.6, 95% CI: 1.1-6.2; and respiratory-related arousal index: ≥7.6/h, OR = 2.3, 95%CI: 1.1-4.7; but not measures of hypoxemia after adjustment for age, hypertension, diabetes, smoking, obesity, and NSAID use. There was no association of CKD with daytime sleepiness. In men with CKD, those with OSA were not significantly more likely to report symptoms (sleepiness, snoring, and apneas) or be identified with the STOP OSA screening questionnaire, compared to men without OSA. Conclusions: Predominantly mild CKD is associated with severe OSA and arousals. Further population studies examining the longitudinal relationship between CKD and OSA are warranted. Better methods are needed to identify OSA in CKD which may have few symptoms.

Hypertension Is Associated With Undiagnosed OSA During Rapid Eye Movement Sleep.

BACKGROUND: Evidence linking OSA with hypertension in population studies is conflicting. We examined longitudinal and cross-sectional associations of previously unrecognized OSA, including OSA occurring in rapid eye movement (REM) sleep, with hypertension. METHODS: The Men Androgens Inflammation Lifestyle Environment and Stress (MAILES) study is a longitudinal study of community-dwelling men in Adelaide, South Australia. Biomedical assessments at baseline (2002-2006) and follow-up (2007-2010) identified hypertension (systolic ≥ 140 mm Hg and/or diastolic ≥ 90 mm Hg, or medication) and risk factors. In 2010 to 2011, 837 men without a prior diagnosis of OSA underwent full in-home unattended polysomnography of whom 739 recorded ≥ 30 min of REM sleep. Hypertension at follow-up (concomitant with OSA status) was defined as prevalent hypertension. Recent-onset hypertension was defined as hypertension at biomedical follow-up (56 months mean follow-up [range, 48-74]) in men free of hypertension at baseline. RESULTS: Severe REM OSA (apnea hypopnea index ≥30/h) showed independent adjusted associations with prevalent (OR, 2.40, 95% CI, 1.42-4.06), and recent-onset hypertension (2.24 [1.04-4.81]). Significant associations with non-REM AHI were not seen. In men with AHI < 10, REM OSA (apnea hypopnea index) ≥ 20/h was significantly associated with prevalent hypertension (2.67 [1.33-5.38]) and the relationship with recent-onset hypertension was positive but not statistically significant (2.32 [0.79-6.84]). Similar results were seen when analyses were confined to men with non-REM AHI < 10. CONCLUSIONS: In men not considered to have OSA (AHI < 10), hypertension was associated with OSA during REM sleep. REM OSA may need consideration as an important clinical entity requiring treatment but further systematic assessment and evidence is needed.

Immunolocalization of NLRP3 Inflammasome in Normal Murine Airway Epithelium and Changes following Induction of Ovalbumin-Induced Airway Inflammation.

Little is known about innate immunity and components of inflammasomes in airway epithelium. This study evaluated immunohistological evidence for NLRP3 inflammasomes in normal and inflamed murine (Balb/c) airway epithelium in a model of ovalbumin (OVA) induced allergic airway inflammation. The airway epithelium of control mice exhibited strong cytoplasmic staining for total caspase-1, ASC, and NLRP3, whereas the OVA mice exhibited strong staining for active caspase-1, with redistribution of caspase-1, IL-1ß and IL-18, indicating possible activation of the NLRP3 inflammasome. Active caspase-1, NLRP3, and other inflammasome components were also detected in tissue eosinophils from OVA mice, and may potentially contribute to IL-1ß and IL-18 production. In whole lung, inRNA expression of NAIP and procaspase-1 was increased in OVA mice, whereas NLRP3, IL-1ß and IL-18 decreased. Some OVA-treated mice also had significantly elevated and tightly correlated serum levels of IL-1ß and TNFα. In cultured normal human bronchial epithelial cells, LPS priming resulted in a significant increase in NLRP3 and II-lp protein expression. This study is the first to demonstrate NLRP3 inflammasome components in normal airway epithelium and changes with inflammation. We propose activation and/or luminal release of the inflammasome is a feature of allergic airway inflammation which may contribute to disease pathogenesis.

Zinc and zinc transporter regulation in pancreatic islets and the potential role of zinc in islet transplantation.

The critical trace element zinc is essential for normal insulin production, and plays a central role in cellular protection against apoptosis and oxidative stress. The regulation of zinc within the pancreas and ß-cells is controlled by the zinc transporter families ZnT and ZIP. Pancreatic islets display wide variability in the occurrence of these molecules. The zinc transporter, ZnT8 is an important target for autoimmunity in type 1 diabetes. Gene polymorphisms of this transporter confer sensitivity for immunosuppressive drugs used in islet transplantation. Understanding the biology of zinc transport within pancreatic islets will provide insight into the mechanisms of ß-cell death, and may well reveal new pathways for improvement of diabetes therapy, including islet transplantation. This review discusses the possible roles of zinc in ß-cell physiology with a special focus on islet transplantation.

The anatomy, physics, and physiology of gas exchange surfaces: is there a universal function for pulmonary surfactant in animal respiratory structures?

(Orgeig and Daniels) This surfactant symposium reflects the integrative and multidisciplinary aims of the 1st ICRB, by encompassing in vitro and in vivo research, studies of vertebrates and invertebrates, and research across multiple disciplines. We explore the physical and structural challenges that face gas exchange surfaces in vertebrates and insects, by focusing on the role of the surfactant system. Pulmonary surfactant is a complex mixture of lipids and proteins that lines the air-liquid interface of the lungs of all air-breathing vertebrates, where it functions to vary surface tension with changing lung volume. We begin with a discussion of the extraordinary conservation of the blood-gas barrier among vertebrate respiratory organs, which has evolved to be extremely thin, thereby maximizing gas exchange, but simultaneously strong enough to withstand significant distension forces. The principal components of pulmonary surfactant are highly conserved, with a mixed phospholipid and neutral lipid interfacial film that is established, maintained and dynamically regulated by surfactant proteins (SP). A wide variation in the concentrations of individual components exists, however, and highlights lipidomic as well as proteomic adaptations to different physiological needs. As SP-B deficiency in mammals is lethal, oxidative stress to SP-B is detrimental to the biophysical function of pulmonary surfactant and SP-B is evolutionarily conserved across the vertebrates. It is likely that SP-B was essential for the evolutionary origin of pulmonary surfactant. We discuss three specific issues of the surfactant system to illustrate the diversity of function in animal respiratory structures. (1) Temperature: In vitro analyses of the behavior of different model surfactant films under dynamic conditions of surface tension and temperature suggest that, contrary to previous beliefs, the alveolar film may not have to be substantially enriched in the disaturated phospholipid, dipalmitoylphosphatidylcholine (DPPC), but that similar properties of rate of film formation can be achieved with more fluid films. Using an in vivo model of temperature change, a mammal that enters torpor, we show that film structure and function varies between surfactants isolated from torpid and active animals. (2) Spheres versus tubes: Surfactant is essential for lung stabilization in vertebrates, but its function is not restricted to the spherical alveolus. Instead, surfactant is also important in narrow tubular respiratory structures such as the terminal airways of mammals and the air capillaries of birds. (3). Insect tracheoles: We investigate the structure and function of the insect tracheal system and ask whether pulmonary surfactant also has a role in stabilizing these minute tubules. Our theoretical analysis suggests that a surfactant system may be required, in order to cope with surface tension during processes, such as molting, when the tracheae collapse and fill with water. Hence, despite observations by Wigglesworth in the 1930s of fluid-filled tracheoles, the challenge persists into the 21st century to determine whether this fluid is associated with a pulmonary-type surfactant system. Finally, we summarize the current status of the field and provide ideas for future research.

Stretch and CO2 modulate the inflammatory response of alveolar macrophages through independent changes in metabolic activity.

Ventilatory-induced strain can exacerbate acute lung injury (ALI). Current ventilation strategies favour low tidal volumes and high end-expiratory volumes to 'rest' the lung, but can lead to an increase in CO2. Alveolar macrophages (AM) play a pivotal role in ALI through the release of inflammatory mediators. The effect of physical strain and CO2 on the release of pro-inflammatory mediators was examined in isolated rat AM. AM were cultured on IgG-coated silastic membranes with or without lipopolysaccharide (LPS) and 5% or 20% CO2 and subjected to a repetitive sinusoidal mechanical strain (30%, 60 cycles/min) for 4 h. Cell viability and metabolic activity were assessed. In both the presence and absence of LPS, physical strain increased metabolic activity by approximately 5%, while 20% CO2 decreased metabolic activity by approximately 40%. Twenty per cent CO2 decreased TNF-alpha secretion by approximately 45%, without affecting cell viability. Physical strain enhanced LPS-induced secretion of TNF-alpha by 1.5%, but not IL-6 or CINC-1. Hence, the effects of both CO2 and physical strain are mediated independently through changes in AM metabolic activity. Physical strain is not a major determinant of TNF-alpha, IL-6 or CINC-1 in AM. Our results confirm that high CO2 can lessen the TNF-alpha inflammatory response of AM.

Effect of CO2 on LPS-induced cytokine responses in rat alveolar macrophages.

Alveolar macrophages (AM) may be exposed to a range of CO(2) and pH levels depending on their location in the alveoli and the health of the lung. Cytokines produced by AM contribute to inflammation in acute lung injury (ALI). Current ventilatory practices for the management of ALI favor low tidal volumes, which can give rise to increases in CO(2) and changes in pH of the alveolar microenvironment. Here we examined the effect of CO(2) on cytokine release from LPS-stimulated rat AM. AM were incubated for 1-4 h under different atmospheric gas mixtures ranging from 2.5-20% CO(2). To distinguish between effects of pH and CO(2), the culture media were also buffered to pH 7.2 with NaHCO(3). Cell metabolic activity, but not cell viability, decreased and increased significantly after 4 h at 20 and 2.5% CO(2), respectively. Increasing CO(2) decreased TNF-alpha secretion but had no effect on lysate TNF-alpha. Buffering the media abated the effects of CO(2) on TNF-alpha secretion. CO(2) increased cytokine-induced neutrophil chemoattractant factor-1 secretion only when the pH was buffered to 7.2. Effects of CO(2) on cytokine responses were reversible. In conclusion, the effects of CO(2) on cytokine lysate levels and/or secretion in AM are cytokine specific and, depending on both the cytokine and the immediate microenvironment, may be beneficial or detrimental to ALI.

Dipalmitoylphosphatidylcholine is not the major surfactant phospholipid species in all mammals.

Pulmonary surfactant, a complex mixture of lipids and proteins, lowers the surface tension in terminal air spaces and is crucial for lung function. Within an animal species, surfactant composition can be influenced by development, disease, respiratory rate, and/or body temperature. Here, we analyzed the composition of surfactant in three heterothermic mammals (dunnart, bat, squirrel), displaying different torpor patterns, to determine: 1) whether increases in surfactant cholesterol (Chol) and phospholipid (PL) saturation occur during long-term torpor in squirrels, as in bats and dunnarts; 2) whether surfactant proteins change during torpor; and 3) whether PL molecular species (molsp) composition is altered. In addition, we analyzed the molsp composition of a further nine mammals (including placental/marsupial and hetero-/homeothermic contrasts) to determine whether phylogeny or thermal behavior determines molsp composition in mammals. We discovered that like bats and dunnarts, surfactant Chol increases during torpor in squirrels. However, changes in PL saturation during torpor may not be universal. Torpor was accompanied by a decrease in surfactant protein A in dunnarts and squirrels, but not in bats, whereas surfactant protein B did not change in any species. Phosphatidylcholine (PC)16:0/16:0 is highly variable between mammals and is not the major PL in the wombat, dunnart, shrew, or Tasmanian devil. An inverse relationship exists between PC16:0/16:0 and two of the major fluidizing components, PC16:0/16:1 and PC16:0/14:0. The PL molsp profile of an animal species is not determined by phylogeny or thermal behavior. We conclude that there is no single PL molsp composition that functions optimally in all mammals; rather, surfactant from each animal is unique and tailored to the biology of that animal.