Circadian variation of sputum inflammatory cells in mild asthma

Melatonin regulates circadian clock proteins expression in allergic airway inflammation

Asthma demonstrates a strong circadian rhythm with disrupted molecular clock. Melatonin which can directly regulate circadian rhythm has been reported to alleviate asthma, but whether this effect is related to its regulation on circadian clock has not yet been known. Here, female C57BL/6 mice were challenged with ovalbumin (OVA) to establish allergic airway inflammation, and were treated with melatonin or Luzindole to investigate whether the expressions of circadian clock proteins were changed in response to OVA and were affected by exogenous/endogenous melatonin. Airway inflammation, mucus secretion, protein expressions of circadian proteins (Bmal1, Per1, Clock, Timeless, Cry1 and Cry2), melatonin biosynthetase (ASMT, AANAT) and melatonin receptor (Mel-1A/B-R) were analyzed accordingly. The results showed that in the successfully established allergic airway inflammation model, inflammatory cells infiltration, expressions of circadian clock proteins in the lung tissues of OVA-challenged mice were all notably up-regulated as compared to that of the vehicle mice. Meanwhile, the protein expression of ASMT and the level of melatonin in the lung tissues were reduced in allergic mice, while the expression of melatonin receptor Mel-1A/B-R was markedly increased. After addition of exogenous melatonin, the OVA-induced airway inflammation was pronouncedly ameliorated, while simultaneously the OVA-induced expressions of Per1 and Clock were further increased. However, a melatonin receptor antagonist Luzindole further augmented the OVA-induced airway inflammation, accompanied with remarkably decreased expressions of Per1, Bmal1, Cry1 and Cry2 but notably increased expression of Timeless. Collectively, our results demonstrated that the expression of circadian clock proteins was increased in the lungs during allergic airway inflammation, and Per1 was a clock protein that can be regulated by both exogenous and endogenous melatonin, suggesting Per1 may be an important potential circadian clock target for melatonin as a negative regulatory factor against Th2-type airway inflammation.

Myeloid Bmal1 deletion suppresses the house dust mite-induced chronic lung allergy

Asthma is the chronic pulmonary inflammatory response that could lead to respiratory failure when allergic reactions exacerbate. It is featured by type 2 immunity with eosinophilic inflammation, mucus, and IgE production, and Th2 cytokine secretion upon repeated challenge of allergens. The symptom severity of asthma displays an apparent circadian rhythm with aggravated airway resistance in the early morning in patients. Bmal1 is the core regulator of the circadian clock, while the regulatory role of Bmal1 in asthma remains unclear. Here, we investigate whether the myeloid Bmal1 is involved in the pathogenesis of house dust mite (HDM)-induced lung allergy. We found that knockdown of Bmal1 in macrophages suppressed the time-of-day variance of the eosinophil infiltration in the alveolar spaces in chronic asthmatic mice. This was accompanied by decreased bronchial mucus production, collagen deposition, and HDM-specific IgE production. However, the suppression effects of myeloid Bmal1 deletion did not alter the allergic responses in short-term exposure to HDM. The transcriptome profile of alveolar macrophages (AMs) showed that Bmal1-deficient AMs have enhanced phagocytosis and reduced production of allergy-mediating prostanoids thromboxane A2 and prostaglandin F2α synthesis. The attenuated thromboxane A2 and prostaglandin F2α may lead to less induction of the eosinophil chemokine Ccl11 expression in bronchial epithelial cells. In summary, our study demonstrates that Bmal1 ablation in macrophages attenuates eosinophilic inflammation in HDM-induced chronic lung allergy, which involves enhanced phagocytosis and reduced prostanoid secretion.

Questionnaire for diagnosing asthma-COPD overlap in COPD: Development of ACO screening questionnaire (ACO-Q)

BACKGROUND

The considerable prevalence and worse outcomes of asthma-COPD overlap (ACO) in COPD have been reported, and optimal introduction of ICS is essential for ACO. However, diagnostic criteria for ACO consist of multiple laboratory tests, which is challenging during this COVID-19 era. The purpose of this study was to create a simple questionnaire to diagnose ACO in patients with COPD.

METHODS

Among 100 COPD patients, 53 were diagnosed with ACO based on the Japanese Respiratory Society Guidelines for ACO. Firstly, 10 candidate questionnaire items were generated and further selected by a logistic regression model. An integer-based scoring system was generated based on the scaled estimates of items.

RESULTS

Five items, namely a history of asthma, wheezing, dyspnea at rest, nocturnal awakening, and weather- or season-dependent symptoms, contributed significantly to the diagnosis of ACO in COPD. History of asthma was related to FeNO >35 ppb. Two points were assigned to history of asthma and 1 point to other items in the ACO screening questionnaire (ACO-Q), and the area under the receiver operating characteristic curve was 0.883 (95% CI: 0.806-0.933). The best cutoff point was 1 point, and the positive predictive value was 100% at a cutoff of 3 points or higher. The result was reproducible in the validation cohort of 53 patients with COPD.

CONCLUSIONS

A simple questionnaire, ACO-Q, was developed. Patients with scores ≥3 could be reasonably recommended to be treated as ACO, and additional laboratory testing would be recommended for patients with 1 and 2 points.

Clinical Potential of Eosinophil-Derived Neurotoxin in Asthma Management

The assessment and management of patients with asthma is challenging because of the complexity of the underlying inflammatory mechanisms and heterogeneity of their clinical presentation. Optimizing disease management requires therapy individualization that should rely on reliable biomarkers to unravel the phenotypes and endotypes of asthma. The secretory activity and turnover of eosinophils, as assessed by measuring eosinophil-derived proteins, may provide an accurate and complementary tool that mirrors the eosinophil activation status. Emerging evidence suggests that eosinophil-derived neurotoxin has considerable potential as a precision medicine biomarker. In this review, we explore the suitability of eosinophil-derived neurotoxin as a biomarker in asthma management, with particular emphasis on its clinical significance in the management of both pediatric and adult populations.

Macrophage circadian rhythms are differentially affected based on stimuli

Macrophages are white blood cells that play disparate roles in homeostasis and immune responses. They can reprogram their phenotypes to pro-inflammatory (M1) or anti-inflammatory (M2) states in response to their environment. About 8-15% of the macrophage transcriptome has circadian oscillations, including genes closely related to their functioning. As circadian rhythms are associated with cellular phenotypes, we hypothesized that polarization of macrophages to opposing subtypes might differently affect their circadian rhythms. We tracked circadian rhythms in RAW 264.7 macrophages using luminescent reporters. Cells were stably transfected with Bmal1:luc and Per2:luc reporters, representing positive and negative components of the molecular clock. Strength of rhythmicity, periods and amplitudes of time series were assessed using multiple approaches. M1 polarization decreased amplitudes and rhythmicities of Bmal1:luc and Per2:luc, but did not significantly affect periods, while M2 polarization increased periods but caused no substantial alterations to amplitudes or rhythmicity. As macrophage phenotypes are also altered in the presence of cancer cells, we tested circadian effects of conditioned media from mouse breast cancer cells. Media from highly aggressive 4T1 cells caused loss of rhythmicity, while media from less aggressive EMT6 cells yielded no changes. As macrophages play roles in tumors, and oncogenic features are associated with circadian rhythms, we tested whether conditioned media from macrophages could alter circadian rhythms of cancer cells. Conditioned media from RAW 264.7 cells resulted in lower rhythmicities and periods, but higher amplitudes in human osteosarcoma, U2OS-Per2:luc cells. We show that phenotypic changes in macrophages result in altered circadian characteristics and suggest that there is an association between circadian rhythms and macrophage polarization state. Additionally, our data demonstrate that macrophages treated with breast cancer-conditioned media have circadian phenotypes similar to those of the M1 subtype, and cancer cells treated with macrophage-conditioned media have circadian alterations, providing insight to another level of cross-talk between macrophages and cancer.

Adaptive immunity, chronic inflammation and the clock

The adaptive arm of the immune system facilitates recognition of specific foreign pathogens and, via the action of T and B lymphocytes, induces a fine-tuned response to target the pathogen and develop immunological memory. The functionality of the adaptive immune system exhibits daily 24-h variation both in homeostatic processes (such as lymphocyte trafficking and development of T lymphocyte subsets) and in responses to challenge. Here, we discuss how the circadian clock exerts influence over the function of the adaptive immune system, considering the roles of cell intrinsic clockwork machinery and cell extrinsic rhythmic signals. Inappropriate or misguided actions of the adaptive immune system can lead to development of autoimmune diseases such as rheumatoid arthritis, ulcerative colitis and multiple sclerosis. Growing evidence indicates that disturbance of the circadian clock has negative impact on development and progression of these chronic inflammatory diseases and we examine current understanding of clock-immune interactions in the setting of these inflammatory conditions. A greater appreciation of circadian control of adaptive immunity will facilitate further understanding of mechanisms driving daily variation in disease states and drive improvements in the diagnosis and treatment of chronic inflammatory diseases.

Temporal Modulation of Drug Desensitization Procedures

Drug hypersensitivity reactions are an unavoidable clinical consequence of the presence of new therapeutic agents. These adverse reactions concern patients afflicted with infectious diseases (e.g., hypersensitivity to antibiotics), and with non-infectious chronic diseases, such as in cancers, diabetes or cystic fibrosis treatments, and may occur at the first drug administration or after repeated exposures. Here we revise recent key studies on the mechanisms underlying the desensitization protocols, and propose an additional temporal regulation layer that is based on the circadian control of the signaling pathway involved and on the modulation of the memory effects established by the desensitization procedures.

Intertwining roles of circadian and metabolic regulation of the innate immune response

It has emerged that an interconnected relationship exists between metabolism, circadian rhythms, and the immune system. The relationship between metabolism and circadian rhythms is not that surprising given the necessity to align rhythms of feeding/fasting with activity/rest. Recently, our understanding of the importance of metabolic pathways in terms of immune function, termed immunometabolism, has grown exponentially. It is now appreciated that the time of day during which the innate immune system is challenged strongly conditions the subsequent response. Recent observations have found that many individual components that make up the circadian clock also control aspects of metabolism in innate immune cells to modulate inflammation. This circadian/metabolic axis may be a key factor driving rhythmicity of immune function and circadian disruption is associated with a range of chronic inflammatory diseases such as atherosclerosis, obesity, and diabetes. The field of "circadian immunometabolism" seeks to reveal undiscovered circadian controlled metabolic pathways that in turn regulate immune responses. The innate immune system has been intricately linked to chronic inflammatory diseases, and within the immune system, individual cell types carry out unique roles in inflammation. Therefore, circadian immunometabolism effects are unique to each innate immune cell.

Responsivity and Reproducibility of Sputum Inflammatory Biomarkers During COPD Exacerbation and Stable Phases - A Pilot Study

INTRODUCTION

There is a great interest to identify airway biomarkers to evaluate the potential and efficacy of anti-inflammatory therapeutic interventions. In this pilot study, we compared cytokine mRNA and protein levels of IL-6, IL-8, CCL2, CCL4, and TNF-α, as well as LTB-4 expression regarding their reproducibility and responsivity in induced sputum in COPD patients.

METHODS

We recruited a cohort of 17 patients with a moderate COPD exacerbation, necessitating antibiotics and/or oral corticosteroids. Patients were followed for two consecutive stable phase visits. Cytokine mRNA and protein levels were measured in induced sputum samples.

RESULTS

IL-6 and CCL4 protein levels decreased from exacerbation to stable phase, whereas their mRNA expression showed the same trend (not statistically significant). Coefficients of variation were overall lower (ie, more favorable for responsiveness) at protein levels compared to mRNA levels. No significant differences were observed in the reproducibility between cytokine mRNA expression and protein measurements. IL-6, IL-8, CCL2, and TNF-α gene expression levels yielded moderate to high intraclass correlation coefficients and/or Spearman correlation coefficients between both stable phase samples in contrast to their protein levels.

CONCLUSION

Our findings suggest that several protein levels yield better responsivity with lower noise-to-signal ratios compared to their respective mRNA levels. In contrast, cytokine mRNA expression was more reproducible as it varied less in a stable state than proteins. Future studies are needed with a larger sample size to further evaluate the differences of responsivity and reproducibility between cytokine mRNA and protein measurements, not only during exacerbations.

The commutability of enzyme linked immunosorbent assays for the quantification of serum eosinophil-derived neurotoxin (EDN)

Eosinophil-derived neurotoxin (EDN) is a surrogate biomarker of eosinophil activation and has considerable potential as a precision medicine biomarker in diseases where eosinophils may play a causative role. Clinical data for EDN have been generated using different quantitative immunoassays, but comparisons between these individual data sets are challenging as no internationally recognised EDN standards or orthogonal methods exist. In this study we aimed to compare commercial EDN assays from ALPCO, MBL, LSBio and CUSABIO for sample commutability. Firstly, we analytically validated the ALPCO enzyme linked immunosorbent assay (ELISA) and demonstrated appropriate analytical characteristics, including an intra/inter-assay precision coefficient-of-variation of between 1.9 and 6.8%. EDN purified from blood proved to be a good quality control material, whereas recombinant EDN, expressed in E.coli, did not react in the ALPCO immunoassay. Using healthy and asthma patient serum samples we confirmed that the ALPCO assay correlated well with the MBL assay, with a coefficient of determination (R²) of 0.92. However, the results from LSBio and CUSABIO assays were not commutable to the other assays.

Circadian immune circuits

Immune responses are gated to protect the host against specific antigens and microbes, a task that is achieved through antigen- and pattern-specific receptors. Less appreciated is that in order to optimize responses and to avoid collateral damage to the host, immune responses must be additionally gated in intensity and time. An evolutionary solution to this challenge is provided by the circadian clock, an ancient time-keeping mechanism that anticipates environmental changes and represents a fundamental property of immunity. Immune responses, however, are not exclusive to immune cells and demand the coordinated action of nonhematopoietic cells interspersed within the architecture of tissues. Here, we review the circadian features of innate immunity as they encompass effector immune cells as well as structural cells that orchestrate their responses in space and time. We finally propose models in which the central clock, structural elements, and immune cells establish multidirectional circadian circuits that may shape the efficacy and strength of immune responses and other physiological processes.

Circadian rhythms in the tissue-specificity from metabolism to immunity; insights from omics studies

Creatures on earth have the capacity to preserve homeostasis in response to changing environments. The circadian clock enables organisms to adapt to daily predictable rhythms in surrounding conditions. In mammals, circadian clocks constitute hierarchical network, where the central pacemaker in hypothalamic suprachiasmatic nucleus (SCN) serves as a time-keeping machinery and governs peripheral clocks in every other organ through descending neural and humoral factors. The central clock in SCN is reset by light, whilst peripheral clocks are entrained by feeding-fasting rhythms, emphasizing the point that temporal patterns of nutrient availability specifies peripheral clock functions. Indeed, emerging evidence revealed various types of diets or timing of food intake reprogram circadian rhythms in a tissue specific manner. This advancement in understanding of mechanisms underlying tissue specific responsiveness of circadian oscillators to nutrients at the genomic and epigenomic levels is largely owing to employment of state-of-the-art technologies. Specifically, high-throughput transcriptome, proteome, and metabolome have provided insights into how genes, proteins, and metabolites behave over circadian cycles in a given tissue under a certain dietary condition in an unbiased fashion. Additionally, combinations with specialized types of sequencing such as nascent-seq and ribosomal profiling allow us to dissect how circadian rhythms are generated or obliterated at each step of gene regulation. Importantly, chromatin immunoprecipitation followed by deep sequencing methods provide chromatin landscape in terms of regulatory mechanisms of circadian gene expression. In this review, we outline recent discoveries on temporal genomic and epigenomic regulation of circadian rhythms, discussing entrainment of the circadian rhythms by feeding as a fundamental new comprehension of metabolism and immune response, and as a potential therapeutic strategy of metabolic and inflammatory diseases.

Eosinophil-derived neurotoxin: A biologically and analytically attractive asthma biomarker

There is a growing body of evidence for the utility of eosinophil-derived neurotoxin (EDN) as a biomarker in asthma, including association with eosinophilic airway inflammation, assessment of disease severity and potential for predicting pathogenic risks, including exacerbations. However, to interpret any biomarker data with confidence, it is first important to understand the preanalytical factors and biological variation that may affect its reliable measurement and results interpretation. In this study we defined the healthy serum EDN reference range for men and women as 1.98 to 26.10 ng/mL, with no significant gender differences. Smoking did not impact the mean EDN levels and no circadian rhythm was identified for EDN, unlike blood eosinophils (EOS) where levels peaked at 00:00h. EDN expression in different cell types was investigated and shown to occur primarily in eosinophils, indicating they are likely to be the main cellular repository for EDN. We also confirm that the quantification of serum EDN is not influenced by the type of storage tube used, and it is stable at ambient temperature or when refrigerated for at least 7 days and for up to one year when frozen at -20°C or -80°C. In summary, EDN is a stable biomarker that may prove useful in precision medicine approaches by enabling the identification of a subpopulation of asthma patients with activated eosinophils and a more severe form of the disease.

Late Chronotype is Associated with Adolescent Asthma: Assessment Using the Korean-Version MCTQ

Objectives: In the study, we explored whether sleep chronotypes are associated with asthma in adolescents. Methods: We analyzed 24,655 physician-diagnosed adolescent asthmatic patients and 253,775 non-asthmatic adolescent patients from the Korea Youth Risk Behavior Web-based Survey (KYRBWS). Socioeconomic factors, health behaviors factors, psychological factors, and sleep parameters were assessed using the Munich Chronotype Questionnaire (MCTQ). Logistic regression after adjusting for multiple confounders was used to explore the association between sleep chronotype and asthma. Results: The asthmatic adolescent group slept less (≤5 h: 24.3% vs. 23.2%) than the non-asthmatic adolescent group. Mean sleep duration (430.6 ± 95.6 vs. 433.5 ± 93.6 min), midpoint of sleep on school-free days (MSF; 255.9 ± 75.9 vs. 258.3 ± 73.6 min), midpoint of sleep on school days (MSW; 199.1 ± 49.1 vs. 200.1 ± 48.4 min), sleep duration on school days (SDW; 398.2 ± 98.1 vs. 400.2 ± 96.8 min), and sleep duration on school-free days (SDF; 511.8 ± 151.9 vs. 516.7 ± 147.2 min) were significantly lower, sleep satisfaction was significantly poorer (low sleep satisfaction: 41.3% vs. 37.5%), and late chronotype was significantly higher in the asthmatic adolescent (21.1% vs. 20.0%). After adjusting for multiple confounders, late chronotype was significantly associated with an increased frequency of adolescent asthma (OR 1.05; 95% CI 1.01–1.09) compared to intermediate chronotypes. Conclusions: Although our study shows a very modest association (OR of 1.05 in the fully adjusted model), we show that the late sleep chronotype is associated with asthma in adolescents in South Korea.

Circadian patterns of hallucinatory experiences in patients with schizophrenia: Potentials for chrono-pharmacology

The objective of this study was to investigate possible circadian pattern of psychotic symptoms in patients with schizophrenia, which could be reflected on the dosing schedule/regimen, i.e. chrono-pharmacology. Patients with schizophrenia (ICD-10) who reported having auditory hallucination, receiving monotherapy with risperidone, olanzapine or paliperidone for at least two weeks were included. The subjects were provided a diary and asked to record the time and duration of auditory hallucinations during the eight time periods (i.e. 00:00-03:00, 03:00-06:00, 06:00-09:00, 09:00-12:00, 12:00-15:00, 15:00-18:00, 18:00-21:00, and 21:00-24:00). In the diary, times of medication doses and sleep were also recorded. Time and degree of peak and trough dopamine D₂ receptor blockade with antipsychotics were estimated from 2 sparsely collected plasma drug concentrations. The prevalence and duration of auditory hallucinations were statistically examined among the eight time periods, respectively. Forty-nine patients participated in this study (mean ± SD age, 50.7 ± 14.8 years; 36 men (73.5%); 34 inpatients (69.4%)). Auditory hallucinations occurred most frequently and lasted for the longest duration in the period of 18:00-21:00 (75.5% (37/49) and 1.37 ± 1.67 h). This happened despite the fact that the difference in D₂ receptor occupancy between the peak and trough was less than 2%, indicating a stable drug delivery. Since the dopamine D₂ receptor blockade by antipsychotics was stable, the nocturnal circadian pattern found in this study may reflect intrinsic dopaminergic fluctuation or generally quieter environments at night. These circadian patterns may be considered to devise individualized treatment approach in the context of "chrono-pharmacology" for patients with schizophrenia.

Time-of-Day-Dependent Trafficking and Function of Leukocyte Subsets

The number of leukocytes circulating in blood in mammals is under circadian control (i.e., ∼24h). We summarize here latest findings on the mechanisms governing leukocyte migration from the blood into various organs, focusing on the distinct leukocyte subtype- and tissue-specific molecules involved. We highlight the oscillatory expression patterns of adhesion molecules, chemokines, and their receptors that are expressed on endothelial cells and leukocytes, and which are crucial regulators of rhythmic leukocyte recruitment. We also discuss the relevance of clock genes for leukocyte function and migration. Finally, we compare immune cell rhythms under steady-state conditions as well as during inflammation and disease, and we postulate how these findings provide potential new avenues for therapeutic intervention.

Clocking in to immunity

Circadian rhythms are a ubiquitous feature of virtually all living organisms, regulating a wide diversity of physiological systems. It has long been established that the circadian clockwork plays a key role in innate immune responses, and recent studies reveal that several aspects of adaptive immunity are also under circadian control. We discuss the latest insights into the genetic and biochemical mechanisms linking immunity to the core circadian clock of the cell and hypothesize as to why the immune system is so tightly controlled by circadian oscillations. Finally, we consider implications for human health, including vaccination strategies and the emerging field of chrono-immunotherapy.

Prevalence and Risk Factors of Asthma and Allergy-Related Diseases among Adolescents (PERFORMANCE) study: rationale and methods

Despite a considerable number of international reports on allergic diseases among children, information about the prevalence and risk factors of asthma and allergy-related diseases among Indian adolescents is relatively sparse. The Prevalence and Risk Factors of Asthma and Allergy-Related Diseases among Adolescents (PERFORMANCE) study has been conceived to study the aetiology of asthma and allergic diseases including rhinoconjunctivitis, atopic eczema and food allergies among adolescents in West Bengal, India, using standardised methods and collaborations. The aims of the study are: 1) to estimate the prevalence and risk factors of asthma and allergic diseases among the adolescents residing in rural, suburban and urban areas of West Bengal; 2) to obtain information about the possible role of lifestyle factors (smoking, diet and physical activity) on the disease prevalence; and 3) to create a network for further investigation on social, environmental and genetic factors affecting the diseases. The PERFORMANCE study comprises two phases. The phase I study will investigate the prevalence and possible contributing factors of asthma and allergic diseases in a defined population. The phase II study will be performed as a follow-up of phase I to assess the incidence of asthma and allergic diseases.

The PERFORMANCE study: investigating the prevalence and risk factors of allergy and asthma among Indian adolescentshttp://ow.ly/jP2v30kmt8u

Redox regulation of circadian molecular clock in chronic airway diseases

At the cellular level, circadian timing is maintained by the molecular clock, a family of interacting clock gene transcription factors, nuclear receptors and kinases called clock genes. Daily rhythms in pulmonary function are dictated by the circadian timing system, including rhythmic susceptibility to the harmful effects of airborne pollutants, exacerbations in patients with chronic airway disease and the immune-inflammatory response to infection. Further, evidence strongly suggests that the circadian molecular clock has a robust reciprocal interaction with redox signaling and plays a considerable role in the response to oxidative/carbonyl stress. Disruption of the circadian timing system, particularly in airway cells, impairs pulmonary rhythms and lung function, enhances oxidative stress due to airway inhaled pollutants like cigarette smoke and airborne particulate matter and leads to enhanced inflammosenescence, inflammasome activation, DNA damage and fibrosis. Herein, we briefly review recent evidence supporting the role of the lung molecular clock and redox signaling in regulating inflammation, oxidative stress, and DNA damage responses in lung diseases and their exacerbations. We further describe the potential for clock genes as novel biomarkers and therapeutic targets for the treatment of chronic lung diseases.

Comparison of sputum collection methods for tuberculosis diagnosis: a systematic review and pairwise and network meta-analysis

BACKGROUND

The performance of laboratory tests to diagnose pulmonary tuberculosis is dependent on the quality of the sputum sample tested. The relative merits of sputum collection methods to improve tuberculosis diagnosis are poorly characterised. We therefore aimed to investigate the effects of sputum collection methods on tuberculosis diagnosis.

METHODS

We did a systematic review and meta-analysis to investigate whether non-invasive sputum collection methods in people aged at least 12 years improve the diagnostic performance of laboratory testing for pulmonary tuberculosis. We searched PubMed, Google Scholar, ProQuest, Web of Science, CINAHL, and Embase up to April 14, 2017, to identify relevant experimental, case-control, or cohort studies. We analysed data by pairwise meta-analyses with a random-effects model and by network meta-analysis. All diagnostic performance data were calculated at the sputum-sample level, except where authors only reported data at the individual patient-level. Heterogeneity was assessed, with potential causes identified by logistic meta-regression.

FINDINGS

We identified 23 eligible studies published between 1959 and 2017, involving 8967 participants who provided 19 252 sputum samples. Brief, on-demand spot sputum collection was the main reference standard. Pooled sputum collection increased tuberculosis diagnosis by microscopy (odds ratio [OR] 1·6, 95% CI 1·3-1·9, p<0·0001) or culture (1·7, 1·2-2·4, p=0·01). Providing instructions to the patient before sputum collection, during observed collection, or together with physiotherapy assistance increased diagnostic performance by microscopy (OR 1·6, 95% CI 1·3-2·0, p<0·0001). Collecting early morning sputum did not significantly increase diagnostic performance of microscopy (OR 1·5, 95% CI 0·9-2·6, p=0·2) or culture (1·4, 0·9-2·4, p=0·2). Network meta-analysis confirmed these findings, and revealed that both pooled and instructed spot sputum collections were similarly effective techniques for increasing the diagnostic performance of microscopy.

INTERPRETATION

Tuberculosis diagnoses were substantially increased by either pooled collection or by providing instruction on how to produce a sputum sample taken at any time of the day. Both interventions had a similar effect to that reported for the introduction of new, expensive laboratory tests, and therefore warrant further exploration in the drive to end the global tuberculosis epidemic.

FUNDING

Wellcome Trust, Joint Global Health Trials consortium, Innovation For Health and Development, and Bill & Melinda Gates Foundation.

Day-time variation of serum periostin in asthmatic adults treated with ICS/LABA and adults without asthma

BACKGROUND

We aimed to determine the effect of sampling time during the day on serum periostin levels in adult participants with and without asthma.

METHODS

Serum periostin was measured at 2-h intervals from 0800 to 1800 h in 16 adult participants with stable asthma prescribed inhaled corticosteroid and long-acting beta-agonist therapy, and in 16 otherwise healthy participants without asthma. Mixed linear models were used to compare time zero (08:00 h) with subsequent measurement time for serum periostin for both groups.

RESULTS

In both asthma and non-asthma, the mean (SD) serum periostin levels continuously reduced during the day from 53.5 (13.6) ng/mL at 0800 h to 50.9 (13.4) ng/mL at 1800 h (difference log periostin -0.05, P ≤ 0.001) and 50.5 (13.0) ng/mL at 0800 h to 46.2 (11.5) ng/mL at 1800 h (difference log periostin -0.08, P ≤ 0.001) respectively.

CONCLUSIONS

Periostin values are higher in the morning compared with the afternoon in asthmatic and non-asthmatic adults. The small magnitude of the variation in serum periostin levels suggests that the time of day in which the serum periostin measurements are made is unlikely to influence treatment decisions if a specific serum periostin level is used to predict treatment responsiveness. Trial registration Australia New Zealand Trials Registry (ACTRN12614000072617).

Transcriptome Profiling of the Lungs Reveals Molecular Clock Genes Expression Changes after Chronic Exposure to Ambient Air Particles

The symptoms of asthma, breathlessness, insomnia, etc. all have relevance to pulmonary rhythmic disturbances. Epidemiology and toxicology studies have demonstrated that exposure to ambient air particles can result in pulmonary dysfunction. However, there are no data directly supporting a link between air pollution and circadian rhythm disorder. In the present study, we found that breathing highly polluted air resulted in changes of the molecular clock genes expression in lung by transcriptome profiling analyses in a rodent model. Compared to those exposed to filtered air, in both pregnant and offspring rats in the unfiltered group, key clock genes (Per1, Per2, Per3, Rev-erbα and Dbp) expression level decreased and Bmal1 expression level increased. In both rat dams and their offspring, after continuous exposure to unfiltered air, we observed significant histologic evidence for both perivascular and peribronchial inflammation, increased tissue and systemic oxidative stress in the lungs. Our results suggest that chronic exposure to particulate matter can induce alterations of clock genes expression, which could be another important pathway for explaining the feedbacks of ambient particle exposure in addition to oxidative stress and inflammation.

Circadian molecular clock in lung pathophysiology

Disrupted daily or circadian rhythms of lung function and inflammatory responses are common features of chronic airway diseases. At the molecular level these circadian rhythms depend on the activity of an autoregulatory feedback loop oscillator of clock gene transcription factors, including the BMAL1:CLOCK activator complex and the repressors PERIOD and CRYPTOCHROME. The key nuclear receptors and transcription factors REV-ERBα and RORα regulate Bmal1 expression and provide stability to the oscillator. Circadian clock dysfunction is implicated in both immune and inflammatory responses to environmental, inflammatory, and infectious agents. Molecular clock function is altered by exposomes, tobacco smoke, lipopolysaccharide, hyperoxia, allergens, bleomycin, as well as bacterial and viral infections. The deacetylase Sirtuin 1 (SIRT1) regulates the timing of the clock through acetylation of BMAL1 and PER2 and controls the clock-dependent functions, which can also be affected by environmental stressors. Environmental agents and redox modulation may alter the levels of REV-ERBα and RORα in lung tissue in association with a heightened DNA damage response, cellular senescence, and inflammation. A reciprocal relationship exists between the molecular clock and immune/inflammatory responses in the lungs. Molecular clock function in lung cells may be used as a biomarker of disease severity and exacerbations or for assessing the efficacy of chronotherapy for disease management. Here, we provide a comprehensive overview of clock-controlled cellular and molecular functions in the lungs and highlight the repercussions of clock disruption on the pathophysiology of chronic airway diseases and their exacerbations. Furthermore, we highlight the potential for the molecular clock as a novel chronopharmacological target for the management of lung pathophysiology.

IMMUNOLOGY. An interactive reference framework for modeling a dynamic immune system

Immune cells function in an interacting hierarchy that coordinates the activities of various cell types according to genetic and environmental contexts. We developed graphical approaches to construct an extensible immune reference map from mass cytometry data of cells from different organs, incorporating landmark cell populations as flags on the map to compare cells from distinct samples. The maps recapitulated canonical cellular phenotypes and revealed reproducible, tissue-specific deviations. The approach revealed influences of genetic variation and circadian rhythms on immune system structure, enabled direct comparisons of murine and human blood cell phenotypes, and even enabled archival fluorescence-based flow cytometry data to be mapped onto the reference framework. This foundational reference map provides a working definition of systemic immune organization to which new data can be integrated to reveal deviations driven by genetics, environment, or pathology.

Circadian Clocks in the Hematologic System

The hematologic system performs a number of essential functions, including oxygen transport, the execution of the immune response against tumor cells and invading pathogens, and hemostasis (blood clotting). These roles are performed by erythrocytes (red blood cells), leukocytes (white blood cells), and thrombocytes (platelets), respectively. Critically, circadian rhythms are evident in the function of all 3 cell types. In this review, we describe these oscillations, explore their mechanistic bases, and highlight their key implications. Since erythrocytes are anucleate, circadian rhythms in these cells testify to the existence of a nontranscriptional circadian clock. From a clinical perspective, leukocyte rhythms could underlie daily variation in the severity of allergic reactions, the symptoms of chronic inflammatory diseases, and the body’s response to infection, while the rhythmic properties of thrombocytes may explain daily fluctuations in the incidence of heart attack and stroke. Consequently, the efficacy of treatments for these conditions is likely to depend on the timing of their administration. Last, we outline preliminary evidence that circadian disruption in the hematologic system could contribute to the deleterious effects of poor diet, shift work, and alcohol abuse on human health.

Noninvasive effects measurements for air pollution human studies: methods, analysis, and implications

Human exposure studies, compared with cell and animal models, are heavily relied upon to study the associations between health effects in humans and air pollutant inhalation. Human studies vary in exposure methodology, with some work conducted in controlled settings, whereas other studies are conducted in ambient environments. Human studies can also vary in the health metrics explored, as there exists a myriad of health effect end points commonly measured. In this review, we compiled mini reviews of the most commonly used noninvasive health effect end points that are suitable for panel studies of air pollution, broken into cardiovascular end points, respiratory end points, and biomarkers of effect from biological specimens. Pertinent information regarding each health end point and the suggested methods for mobile collection in the field are assessed. In addition, the clinical implications for each health end point are summarized, along with the factors identified that can modify each measurement. Finally, the important research findings regarding each health end point and air pollutant exposures were reviewed. It appeared that most of the adverse health effects end points explored were found to positively correlate with pollutant levels, although differences in study design, pollutants measured, and study population were found to influence the magnitude of these effects. Thus, this review is intended to act as a guide for researchers interested in conducting human exposure studies of air pollutants while in the field, although there can be a wider application for using these end points in many epidemiological study designs.

The circadian clock is functional in eosinophils and mast cells

Allergic diseases are frequently exacerbated between midnight and early morning, suggesting a role for the biological clock. Mast cells (MC) and eosinophils are the main effector cells of allergic diseases and some MC-specific or eosinophil-specific markers, such as tryptase or eosinophil cationic protein, exhibit circadian variation. Here, we analysed whether the circadian clock is functional in mouse and human eosinophils and MC. Mouse jejunal MC and polymorphonuclear cells from peripheral blood (PMNC) were isolated around the circadian cycle. Human eosinophils were purified from peripheral blood of non-allergic and allergic subjects. Human MC were purified from intestinal tissue. We found a rhythmic expression of the clock genes mPer1, mPer2, mClock and mBmal1 and eosinophil-specific genes mEcp, mEpo and mMbp in murine PMNC. We also found circadian variations for hPer1, hPer2, hBmal1, hClock, hEdn and hEcp mRNA and eosinophil cationic protein (ECP) in human eosinophils of both healthy and allergic people. Clock genes mPer1, mPer2, mClock and mBmal1 and MC-specific genes mMcpt-5, mMcpt-7, mc-kit and mFcεRI α-chain and protein levels of mMCPT5 and mc-Kit showed robust oscillation in mouse jejunum. Human intestinal MC expressed hPer1, hPer2 and hBmal1 as well as hTryptase and hFcεRI α-chain, in a circadian manner. We found that pre-stored histamine and de novo synthesized cysteinyl leukotrienes, were released in a circadian manner by MC following IgE-mediated activation. In summary, the biological clock controls MC and eosinophils leading to circadian expression and release of their mediators and, hence it might be involved in the pathophysiology of allergy.

Circadian rhythms in leukocyte trafficking

A broad range of immunological processes oscillates over the course of a day. Recent findings have identified a molecular basis for the circadian clock in the regulation of the immune system. These rhythms manifest themselves in oscillatory behavior of immune cells and proinflammatory mediators, which causes a time-dependent sensitivity in the reaction to pathogens. This rhythmicity impacts disease manifestations and severity and provides an option for therapy that incorporates chronopharmacological considerations. This review will focus on the current knowledge and relevance of rhythmic immune cell trafficking. It will provide an overview of the molecular clock machinery and its interrelations with leukocyte migration and the immune response.

Evening chronotypes have the increased odds for bronchial asthma and nocturnal asthma

Earlier studies have found associations of chronotypes with a range of health-related factors. In the light of these findings, the behavioral trait of eveningness in particular associates with determinants that might have a negative impact on health. In this study, based on a random sample of population aged 25-74 years living in five large geographical areas in Finland (N = 6089), we tested whether the evening chronotypes have the increased odds for respiratory symptoms and diseases. As a result, after controlling for socio-demographic and lifestyle factors, evening-types had wheezy breathing without respiratory infection, a diagnosed or treated bronchial asthma, awoken in shortness of breath, awoken in heavy to breath, wheezy breathing with dyspnea, wheezy breathing as such and medication for asthma more often than morning-types (odds ratios (ORs) of 1.5-1.9) and intermediate-types (ORs of 1.3-1.6). In addition, evening-types had current medication for asthma, and awoken in coughing more often (OR = 1.5 and OR = 1.4, respectively) than morning-types. Evening-types did not have a diagnosed or treated chronic bronchitis more frequently than others. Our results suggest that the behavioral trait of eveningness associates with the increased odds for the bronchial asthma and nocturnal asthma in particular.

Human eosinophils release IL-1ß and increase expression of IL-17A in activated CD4+ T lymphocytes

BACKGROUND

Differentiation and activation of CD4(+) T cells is controlled by various cytokines produced by innate immune cells. We have shown that eosinophils (EOS) have the potential to influence Th1 and Th2 cytokine generation by CD4(+) cells, but their influence on IL-17A (IL-17) has not been established.

OBJECTIVE

The purpose of this study is to determine the effect of EOS on IL-17 production by lymphocytes.

METHODS

Pre-activated CD4(+) T cells were cultured in the presence of either autologous EOS or EOS culture supernatants. Expression of IL-17 was determined by real-time quantitative PCR (qPCR) after 5 h and protein level was measured after 48 h. To determine the effect of allergen-induced airway EOS on IL-17, subjects with mild allergic asthma underwent bronchoscopic segmental bronchoprovocation with allergen (SBP-Ag) after a treatment with an anti-IL-5 neutralizing antibody (mepolizumab) to reduce airway eosinophilia. IL-17 mRNA was measured in bronchoalveolar lavage (BAL) cells by qPCR.

RESULTS

In vitro, EOS significantly increased IL-17 production by CD4(+) T cells. Addition of exogenous IL-1ß increased expression of IL-17 mRNA by CD4(+) T cells. EOS expressed and released IL-1ß. Furthermore, levels of IL-1ß in EOS supernatants highly correlated with their ability to increase IL-17 expression by CD4(+) T cells, and neutralizing antibody to IL-1ß reduced expression of IL-17 mRNA. In vivo, reduction of EOS in the airway using mepolizumab was associated with diminished IL-17 expression after SBP-Ag.

CONCLUSIONS AND CLINICAL RELEVANCE

Our data demonstrate that EOS can promote IL-17 production through the release of IL-1ß. Enhanced IL-17 cytokine production is another mechanism by which EOS may participate in pathogenesis of allergic airway inflammation in asthma.

The impact of diurnal variation on induced sputum cell counts in healthy adults

BACKGROUND

Induced sputum cell counts are a non-invasive, reliable method for evaluating the presence, type, and degree of inflammation in the airways of the lungs. Current reference values for induced sputum cell counts in healthy adults do not account for the effects of circadian rhythm, including diurnal variation. The objective of this study was to describe the diurnal variation in induced sputum cell counts, compared between early morning and late afternoon, in healthy adult individuals.

METHODS

100 healthy adult subjects with no history of lung disease and normal bronchial reactivity proceeded with induced sputum testing at 7 am and 4 pm on different days. The order of testing was randomized. The cytotechnologist preparing and performing the cell counts was blinded to the sample collection time and subject characteristics.

RESULTS

65 subjects were included in the final analyses. There was no significant change in the total and differential sputum cell counts between the 7 am and 4 pm collections. There was good inter-observer agreement with respect to differential sputum cell count interpretation.

CONCLUSIONS

This is the largest study to assess the variation in induced sputum cell counts in healthy adult subjects at different times of the day. We found no significant change in total and differential sputum cell counts between the 7 am and 4 pm collection time points. This is in contrast to studies in asthmatics that demonstrated a circadian variation in sputum cell counts and other markers of inflammation, suggesting that fluctuations in airway inflammatory cells during the day are a disease-specific effect.

Circadian control of the immune system

Circadian rhythms, which have long been known to play crucial roles in physiology, are emerging as important regulators of specific immune functions. Circadian oscillations of immune mediators coincide with the activity of the immune system, possibly allowing the host to anticipate and handle microbial threats more efficiently. These oscillations may also help to promote tissue recovery and the clearance of potentially harmful cellular elements from the circulation. This Review summarizes the current knowledge of circadian rhythms in the immune system and provides an outlook on potential future implications.

Circadian changes in the sputum of asthmatic subjects and healthy controls

Background

Asthma is exhibiting classical circadian fluctuations of clinical symptoms and airflow measurements, presumably influenced by the underlying airway inflammation and the endogenous cortisol secretion. The aim of our study was to examine the cellular and eosinophilic cationic protein (ECP) contents of sputum, collected and frozen at 2 opposite time points of the day-and-night cycle, and to correlate them to blood cortisol levels.

Methods

Thirteen subjects with uncontrolled asthma (8 men, aged 25-54 years) and 10 healthy subjects (6 men, aged 25-50 years) volunteered for the study. They were induced with hypertonic saline to produce sputum between 8:00 AM and 9:00 AM and between 8:00 PM and 9:00 PM, when blood was also withdrawn to measure cortisol levels.

Results

Asthmatic subjects did not display significant morning/evening differences in their sputum total cell counts ([TCCs] median, 2.06 × 10³ cells/mL; range 0.50-5.66 cells/mL vs median, 1.29 cells/mL; range, 0.24-9.26 cells/mL, P > 0.1), whereas controls had a well-defined morning peak (median, 0.75 cells/mL; range, 0.31-2.25 cells/mL vs median, 0.33 cells/mL; range, 0.1-0.97 cells/mL, P > 0.001). Asthmatic subjects had significantly higher sputum TCC than controls in the evening (P < 0.001), but their morning TCC did not significantly exceed those of the healthy subjects. Asthmatic subjects had significantly more sputum eosinophils and higher ECP levels than controls but failed to demonstrate significant morning/evening differences in contrast to the controls who had higher morning eosinophils and ECP. Macrophages were relatively increased in the evening samples of both asthmatic subjects and controls. No significant correlations between the circadian cortisol shift and any of the sputum indices were found.

Conclusions

Sputum undergoes circadian changes, which are different in health and in asthma and do not correlate with endogenous cortisol levels.

Pre- and postshift levels of inflammatory biomarkers and DNA damage in non-bitumen-exposed construction workers-subpopulation of the German Human Bitumen Study

Circadian variations in immune defense and tissue repair may interfere with shift effects of occupational exposure when investigating biomarkers in cross-shift studies. This investigation compared biomarkers of inflammation and DNA damage in 59 nonsmoking and 59 smoking male construction workers pre- (6-10 a.m.) versus postshift (4-7 p.m.). Cellular compositions were analyzed in blood, induced sputum (IS), and nasal lavage fluid (NALF) and soluble inflammatory biomarkers were analyzed in IS and NALF. DNA damage was measured as 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) adducts and DNA strand breaks (alkaline Comet assay) in white blood cells (WBC). Apoptosis was quantified as percent apoptotic cells by annexin V and 7-amino-actinomycin staining in blood lymphocytes using flow cytometry. In nonsmokers higher preshift than postshift levels of interleukin-8 (IL-8) in IS and more DNA strand breaks were detected. However, more DNA adducts were found postshift. Among smokers, the cellular composition of IS and NALF differed between pre- and postshift samples, in particular more neutrophils pre- than postshift. In contrast, more cells in early apoptosis were observed post shift in both smokers and nonsmokers. These results indicate a potential influence of circadian rhythms on several biomarkers used in epidemiological studies. Data suggest interference with shift-work effects of occupational exposure in cross-shift studies and also the need to consider smoking as a modifying variable.

Asthma and Sleep

Asthma significantly affects quality of sleep. Asthma physiology follows a diurnal pattern with peak flow at its lowest during early morning hours. The type and timing of release of inflammatory mediators also varies during the day and nighttime. Nocturnal symptoms are common in poorly controlled asthma. Hence, these nighttime symptoms play a significant role in the assessment of asthmatic patients as demonstrated in validated asthma control and quality of life questionnaires. Comorbid conditions may include allergic rhinitis, obesity, obstructive sleep apnea, and gastroesophageal reflux, all of which may worsen asthma symptoms, especially during sleep. In addition, exposure to greater loads of allergens in susceptible individuals during sleep is a significant problem and must be addressed to break the cycle of poor asthma control. Thus, asthma education for better symptom control should address these particular issues surrounding sleep.

Evaluating Sleep Characteristics in Intensive Care Unit and Non-Intensive Care Unit Physicians

Healthcare workers’ cognitive performances and alertness are highly vulnerable to sleep loss and circadian rhythms. The purpose of this study was to investigate the changes in sleep characteristics of intensive care unit (ICU) and non-ICU physicians. Actigraphic sleep parameters, Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale and Hamilton Depression Rating Scale were evaluated for ICU and non-ICU physicians on the day before shift-work and on three consecutive days after shift-work. Total sleep time, sleep latency, wakefulness after sleep onset, total activity score, movement fragmentation index, sleep efficiency, daytime naps and total nap duration were also calculated by actigraph. In the ICU physicians, the mean Pittsburgh Sleep Quality Index score was significantly higher than the non-ICU physicians (P=0.001), however mean Epworth Sleepiness Scale scores were not found significantly different between the two groups. None of the scores for objective sleep parameters were statistically different between the groups when evaluated before and after shift-work (P >0.05). However in both ICU and non-ICU physicians, sleep latency was observed to be decreased within the three consecutive-day period after shift-work with respect to basal values (P <0.001). Total sleep time, total activity score and sleep efficiency scores prior to shift-work were significantly different from shift-work and the three consecutive-days after shift-work, in both groups. Working in the ICU does not have an impact on objective sleep characteristics of physicians in this study. Large cohort studies are required to determine long-term health concerns of shift-working physicians.

Circadian changes in granulocyte-macrophage colony-stimulating factor message in circulating eosinophils

BACKGROUND

Granulocyte-macrophage colony-stimulating factor (GM-CSF), which stimulates eosinophil recruitment, activation, and survival, is expressed by activated eosinophils. Although eosinophil recruitment and enhanced survival have been associated with nocturnal asthma (NA), the contribution of GM-CSF to NA is unknown.

OBJECTIVE

To determine whether circulating eosinophil GM-CSF expression correlates with the symptoms of NA.

METHODS

The GM-CSF messenger RNA (mRNA) expression at 4 PM and 4 AM was determined by reverse-transcriptase polymerase chain reaction with Southern blot analysis in subjects with and without NA and in controls.

RESULTS

A total of 142 asthma subjects were screened for nocturnal asthma with 1-week home peak expiratory flow rate (PEFR) monitoring. Eleven subjects had NA (>20% diurnal variation in PEFR on 4 of 7 days), and 6 met the criteria for non-NA (<10% diurnal variation in PEFR on 7 of 7 days); 8 controls were studied. In subjects with NA, GM-CSF mRNA expression in circulating eosinophils increased 3-fold at 4 AM compared with 4 PM. Diurnal changes in GM-CSF mRNA expression were not detected in the non-NA and control groups.

CONCLUSIONS

Day-night variation in eosinophil GM-CSF expression is associated with circadian variation in airway function in asthma, a key manifestation of asthma severity.

The altered homeostatic theory: A hypothesis proposed to be useful in understanding and preventing ischemic heart disease, hypertension, and diabetes – including reducing the risk of age and atherosclerosis

Evidence will be presented to support the usefulness of the altered homeostatic theory in understanding basic pathogenetic mechanisms of ischemic heart disease (IHD), hypertension, and diabetes, and in improving prevention of these disorders. The theory argues that: IHD, hypertension, and diabetes share the same basic pathogenesis; risk factors favor a sympathetic homeostatic shift; preventative factors favor a parasympathetic homeostatic shift; risk and preventative factors oppose each other through a dynamic risk/prevention balance; and prevention should be based on improving the risk/prevention balance. Prevention based on improving the risk/prevention balance should be more effective, as this method is regarded as reflecting more accurately basic pathogenetic mechanisms. As example, the theory argues that the risk of supposedly nonmodifiable risk factors as age and the risk of relatively nonmodifiable atherosclerosis can be reduced significantly. The possible validity of the altered homeostatic theory was tested by a study based on multiple associations. Findings support a common pathogenesis for IHD, hypertension, and diabetes based on a sympathetic homeostatic shift, and the usefulness of prevention based on improving the risk/prevention balance by using standard pharmaceutical and lifestyle preventative measures. The same set of multiple and diverse risk factors favored IHD, hypertension, and diabetes, and the same set of multiple and diverse pharmaceutical and lifestyle preventative measures prevented these disorders. Also, the same set of preventative agents generally improved cognitive function and bone density, and reduced the incidence of Alzheimer's disease, atrial fibrillation, and cancer. Unexpectedly, evidence was developed that four major attributes of sympathetic activation represent four major risk factors; attributes of sympathetic activation are a tendency toward thrombosis and vasoconstriction, lipidemia, inflammation, and hyperglycemia, and corresponding risk factors are endothelial dysfunction (which expresses thrombosis/vasoconstriction and epitomizes this tendency), dyslipidemia, inflammation, and insulin resistance. These findings, plus other information, provide evidence that dyslipidemia acts mainly as a marker of risk of IHD, rather than being the basic mechanism of this disorder. However, prevention generally is based solely on improvement of dyslipidemia; basing prevention on dyslipidemia relatively underemphasizes the importance of other significant risk factors and, by certifying its validity, discourages alternate pathogenetic approaches. Also, development of myocardial infarction is approached differently. It seems generally accepted that dyslipidemia results rather automatically in infarction through the sequence of atherosclerosis, atherosclerotic complications, and thrombosis. In contrast, distinction is made between development of atherosclerosis and acute induction of infarction--where atherosclerosis is only one of multiple risk factors.

Repeated sputum inductions induce a transient neutrophilic and eosinophilic response

INTRODUCTION

Sputum induction is a tool to monitor airway inflammation, yet it may induce by itself a neutrophilic response when repeated within 24 to 48 h. This limits its repeated use in clinical trials.

OBJECTIVE

We aimed to investigate the induction and resolution of inflammation generated by repeated sputum inductions.

SUBJECTS AND DESIGN

Sixteen healthy intermittent smokers participated in a study on the short-term effects of smoking. The nonsmoking arm consisted of seven successive sputum inductions with increasing time intervals (3, 6, 12, 24, 48, and 96 h). Inflammatory cellular characteristics and different soluble mediators were investigated.

MEASUREMENTS AND RESULTS

The median percentage of sputum neutrophils increased significantly from baseline to 6 h (58.9% [range, 31.8 to 94.2%] to 83.2% [range, 26.7 to 98.3%], respectively). Surprisingly, the percentage of eosinophils also increased significantly from baseline to 6, 12, 24, and 48 h, as follows: 0.3% (range, 0.0 to 1.2%) to 1.7% (range, 0.0 to 15.5%), 2.2% (range, 0.5 to 12.5%), 1.2% (range, 0.0 to 4.8%), and 0.8% (range, 0.0 to 2.8%), respectively. Interleukin-8 increased significantly from baseline to 24 h (1,553 pg/mL [range, 462 to 8,192 pg/mL] to 2,178 pg/mL [range, 666 to 128,544 pg/mL]).

CONCLUSIONS

Repeated sputum inductions should preferably be avoided within 48 h. It induces not only a short-lived neutrophilic response but also a prolonged eosinophilic inflammatory response in healthy subjects, possibly by local changes in osmolarity, and subsequent epithelial and/or mast cell activation.

Patient characteristics associated with nocturnal emergency department visits for asthma

STUDY OBJECTIVES

To identify patient characteristics associated with nocturnal emergency department (ED) visits for asthma.

METHODS

Asthmatic patients 18 to 55 years of age who visited Ontario EDs between April 1, 2003 and March 31, 2004, were identified through an administrative clinical database. Patients' time of ED presentation was analyzed for circadian pattern using histogram and polynomial regression. Risk of nocturnal visit (presentation at the ED between midnight and 8 AM) was modeled through generalized estimating equations with patient age, gender, and asthma severity level as covariates. The effect of nocturnal visit on return rate to the ED within 14 days after the initial visit was determined through Cox regression.

RESULTS

During study period there were 31,490 ED visits for asthma made by 23,253 patients. Their time of ED visits displayed a distinct circadian pattern with peak between 7 and 8 PM, and trough at 5 AM. Approximately 22% of visits (6,868) occurred at night. Men had higher odds of presenting at night than women (OR 1.61; 1.49-1.73). Patients with mild asthma were significantly less likely to visit the ED at night than patients with moderate or severe asthma. Nocturnal presentation was not associated with higher odds of subsequent returns to the ED (HR 1.00; 0.89-1.14).

CONCLUSION

Higher odds of nocturnal visits in men suggest the existence of gender-differences in health-seeking behavior in asthmatics. Although nocturnal visits are associated with more severe asthma, they do not lead to higher return rates.

Regulation and modulation of electric waveforms in gymnotiform electric fish

Weakly electric gymnotiform fish specialize in the regulation and modulation of the action potentials that make up their multi-purpose electric signals. To produce communication signals, gymnotiform fish modulate the waveforms of their electric organ discharges (EODs) over timescales spanning ten orders of magnitude within the animal's life cycle: developmental, reproductive, circadian, and behavioral. Rapid changes lasting milliseconds to seconds are the result of direct neural control of action potential firing in the electric organ. Intermediate-term changes taking minutes to hours result from the action of melanocortin peptides, the pituitary hormones that induce skin darkening and cortisol release in many vertebrates. Long-term changes in the EOD waveform taking days to weeks result from the action of sex steroids on the electrocytes in the electric organ as well as changes in the neural control structures in the brain. These long-term changes in the electric organ seem to be associated with changes in the expression of voltage-gated ion channels in two gene families. Electric organs express multiple voltage-gated sodium channel genes, at least one of which seems to be regulated by androgens. Electric organs also express multiple subunits of the shaker (Kv1) family of voltage-gated potassium channels. Expression of the Kv1 subtype has been found to vary with the duration of the waveform in the electric signal. Our increasing understanding of the mechanisms underlying precise control of electric communication signals may yield significant insights into the diversity of natural mechanisms available for modifying the performance of ion channels in excitable membranes. These mechanisms may lead to better understanding of normal function in a wide range of physiological systems and future application in treatment of disease states involving pathology of excitable membranes.

The role of p38 MAPK in rhinovirus-induced monocyte chemoattractant protein-1 production by monocytic-lineage cells

Viral respiratory infections are a major cause of asthma exacerbations and can contribute to the pathogenesis of asthma. Major group human rhinovirus enters cells by binding to the cell surface molecule ICAM-1 that is present on epithelial and monocytic lineage cells. The focus of the resulting viral infection is in bronchial epithelia. However, previous studies of the cytokine dysregulation that follows rhinovirus infection have implicated monocytic lineage cells in establishing the inflammatory environment even though productive infection is not a result. We have determined that human alveolar macrophages and human peripheral blood monocytes release MCP-1 upon exposure to human rhinovirus 16 (HRV16). Indeed, we have found p38 MAPK activation in human alveolar macrophages within 15 min of exposure to HRV16, and this activation lasts up to 1 h. The targets of p38 MAPK activation include transcriptional activators of the MCP-1 promoter. The transcription factor ATF-2, a p38 MAPK substrate, is phosphorylated 45 min after HRV16 exposure. Furthermore, IkappaBalpha, the inhibitor of the transcription factor NF-kappaB, is degraded. Prevention of HRV16 binding was effective in blocking p38 MAPK activation, ATF-2 phosphorylation, and MCP-1 release. This is the first report of a relationship between HRV16 exposure, MCP-1 release and monocytic-lineage cells suggesting that MCP-1 plays a role in establishing the inflammatory microenvironment initiated in the human airway upon exposure to rhinovirus.