The circadian clock and asthma

Diurnal variation in asthma symptoms: Exploring the role of melatonin

BACKGROUND

Asthma is a common chronic inflammatory disease affecting more than 260 million people worldwide. Nocturnal exacerbations of asthma symptoms significantly affect sleep quality and contribute to the most serious asthma exacerbations, which can lead to respiratory failure or death. Although β2-adrenoceptor agonists are the standard of care for asthma, their bronchodilatory effect for nocturnal asthma is limited, and medications that specifically target symptoms of nocturnal asthma are lacking.

HIGHLIGHT

Melatonin, which is secreted by the pineal gland, plays a crucial role in regulating circadian rhythms. Peak serum melatonin concentrations, which are inversely correlated with diurnal changes in pulmonary function, are higher in patients with nocturnal asthma than in healthy individuals. Melatonin potentiates bronchoconstriction through the melatonin MT2 receptor expressed in the smooth muscles of the airway and attenuates the bronchodilatory effects of β2-adrenoceptor agonists, thereby exacerbating asthma symptoms. Melatonin inhibits mucus secretion and airway inflammation, potentially ameliorating asthma symptoms.

CONCLUSION

Melatonin may exacerbate or ameliorate various pathophysiological conditions associated with asthma. As a potential therapeutic agent for asthma, the balance between its detrimental effects on airway smooth muscles and its beneficial effects on mucus production and inflammation remains unclear. Further studies are needed to elucidate whether melatonin worsens or improves asthma symptoms.

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.

The identification of diurnal variations on circulating immune cells by finger prick blood sampling in small sample sizes: a pilot study

OBJECTIVE

There are well-described impacts of biological rhythms on human physiology. With the increasing push for routine blood tests for preventative medical care and clinical and physiological research, optimizing effectiveness is paramount. This study aimed to determine whether it is feasible to assess diurnal variations of peripheral lymphocyte prevalence using finger prick blood in a small sample size.

METHODS

Using polychromatic flow cytometry, the prevalence of lymphocytes was assessed using 25 µL fingertip blood samples at 8 AM and 5 PM from 8 participants.

RESULTS

TH cells and B cells showed significantly higher percentages in the 5 PM samples, whereas NK cells demonstrated a significantly higher morning percentage. T cells, leukocytes, and cytotoxic T cells showed no significant changes.

CONCLUSION

The detection of diurnal variations demonstrates that small blood volumes can be used to detect lymphocyte variations. The lower blood volume required provides a new testing method for clinical and research settings.

Sleep and allergic diseases among young Chinese adults from the Singapore/Malaysia Cross-Sectional Genetic Epidemiology Study (SMCGES) cohort

BACKGROUND AND OBJECTIVE

Sleep disruption has been shown to affect immune function and thus influence allergic disease manifestation. The specific effects of sleep on allergic diseases, however, are less well-established; hence, in a unique population of young Chinese adults, we investigated the association between sleep and allergic disease.

METHODS

Young Chinese adults recruited from Singapore in the Singapore/Malaysia Cross-Sectional Genetic Epidemiology Study (SMCGES) were analyzed. We used the International Study of Asthma and Allergies in Childhood (ISAAC) protocol and a skin prick test to determine atopic dermatitis (AD), allergic rhinitis (AR), and asthma status. Information regarding total sleep time (TST) and sleep quality (SQ) was also obtained.

RESULTS

Of 1558 participants with a mean age of 25.0 years (SD = 7.6), 61.4% were female, and the mean total sleep time (TST) was 6.8 h (SD = 1.1). The proportions of AD, AR, and asthma were 24.5% (393/1542), 36.4% (987/1551), and 14.7% (227/1547), respectively. 59.8% (235/393) of AD cases suffered from AD-related sleep disturbances, 37.1% (209/564) of AR cases suffered from AR-related sleep disturbances, and 25.1% (57/227) of asthma cases suffered from asthma-related sleep disturbances. Only asthma cases showed a significantly lower mean TST than those without asthma (p = 0.015). Longer TST was significantly associated with lower odds of AR (OR = 0.905, 95% CI = 0.820-0.999) and asthma (OR = 0.852, 95% CI = 0.746-0.972). Linear regression analyses showed that lower TST was significantly associated with asthma (β =  - 0.18, SE = 0.076, p-value = 0.017), and AR when adjusted for AR-related sleep disturbances (β =  - 0.157, SE = 0.065, p-value = 0.016). Only sleep disturbances due to AR were significantly associated with a poorer SQ (OR = 1.962, 95% CI = 1.245-3.089).

CONCLUSIONS

We found that sleep quality, but not sleep duration was significantly poorer among AD cases, although the exact direction of influence could not be determined. In consideration of the literature coupled with our findings, we posit that TST influences allergic rhinitis rather than vice versa. Finally, the association between TST and asthma is likely mediated by asthma-related sleep disturbances, since mean TST was significantly lower among those with nighttime asthma symptoms. Future studies could consider using objective sleep measurements coupled with differential expression analysis to investigate the pathophysiology of sleep and allergic diseases.

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.

Clinical characterization of patients with bipolar disorder and a history of asthma: An exploratory study

INTRODUCTION

Bipolar disorder (BD) and asthma are leading causes of morbidity in the US and frequently co-occur.

OBJECTIVES

We evaluated the clinical features and comorbidities of patients with BD and a history of asthma.

METHODS

In a cross-sectional analysis from the Mayo Clinic Bipolar Biobank, we explored the clinical characteristics of the BD and an asthma phenotype and fitted a multivariable regression model to identify risk factors for asthma.

RESULTS

A total of 721 individuals with BD were included. From these, 140 (19%) had a history of asthma. In a multivariable model only sex and evening chronotype were significant predictors of asthma with the odds ratios and 95% confidence intervals being 1.65 (1.00, 2.72; p=0.05) and 1.99 (1.25, 3.17; p < 0.01), respectively. Individuals with asthma had higher odds of having other medical comorbidities after adjusting for age, sex, and site including hypertension (OR = 2.29 (95% CI 1.42, 3.71); p < 0.01), fibromyalgia (2.29 (1.16, 4.51); p=0.02), obstructive sleep apnea (2.03 (1.18, 3.50); p=0.01), migraine (1.98 (1.31, 3.00); p < 0.01), osteoarthritis (2.08 (1.20, 3.61); p < 0.01), and COPD (2.80 (1.14, 6.84); p=0.02). Finally, individuals currently on lithium were less likely to have a history of asthma (0.48 (0.32, 0.71); p < 0.01).

CONCLUSION

A history of asthma is common among patients with BD and is associated with being female and having an evening chronotype, as well as with increased odds of having other medical comorbidities. A lower likelihood of a history of asthma among those currently on lithium is an intriguing finding with potential clinical implications that warrants further study.

BMAL1 regulates MUC1 overexpression in ovalbumin-induced asthma

Asthma often presents with a daily rhythm; however, the underlying mechanisms remain unclear. Circadian rhythm genes have been proposed to regulate inflammation and mucin expression. Here, ovalbumin (OVA)-induced mice and serum shock human bronchial epidermal cells (16HBE) were used in in vivo and in vitro models, respectively. We constructed a brain and muscle ARNT-like 1 (BMAL1) knockdown 16HBE cell line to analyze the effects of rhythmic fluctuations on mucin expression. Serum immunoglobulin E (IgE) and circadian rhythm genes in asthmatic mice showed rhythmic fluctuation amplitude. Mucin (MUC) 1 and MUC5AC expression was increased in the lung tissue of the asthmatic mice. MUC1 expression was negatively correlated with that of the circadian rhythm genes, particularly BMAL1 (r = -0.546, P = 0.006). There was also a negative correlation between BMAL1 and MUC1 expression (r = -0.507, P = 0.002) in the serum shock 16HBE cells. BMAL1 knockdown negated the rhythmic fluctuation amplitude of MUC1 expression and upregulated MUC1 expression in the 16HBE cells. These results indicate that the key circadian rhythm gene, BMAL1, causes periodic changes in airway MUC1 expression in OVA-induced asthmatic mice. Targeting BMAL1 to regulate periodic changes in MUC1 expression may, therefore, improve asthma treatments.

NOX2 inhibition enables retention of the circadian clock in BV2 microglia and primary macrophages

Introduction

Sustained neuroinflammation is a major contributor to the progression of neurodegenerative diseases such as Alzheimer's (AD) and Parkinson's (PD) diseases. Neuroinflammation, like other cellular processes, is affected by the circadian clock. Microglia, the resident immune cells in the brain, act as major contributors to neuroinflammation and are under the influence of the circadian clock. Microglial responses such as activation, recruitment, and cytokine expression are rhythmic in their response to various stimuli. While the link between circadian rhythms and neuroinflammation is clear, significant gaps remain in our understanding of this complex relationship. To gain a greater understanding of this relationship, the interaction between the microglial circadian clock and the enzyme NADPH Oxidase Isoform 2 (NOX2) was studied; NOX2 is essential for the production of reactive oxygen species (ROS) in oxidative stress, an integral characteristic of neuroinflammation.

Methods

BV2 microglia were examined over circadian time, demonstrating oscillations of the clock genes Per2 and Bmal1 and the NOX2 subunits gp91phox and p47phox.

Results

The BV2 microglial clock exerted significant control over NOX2 expression and inhibition of NOX2 enabled the microglia to retain a functional circadian clock while reducing levels of ROS and inflammatory cytokines. These trends were mirrored in mouse bone marrow-derived primary macrophages.

Conclusions

NOX2 plays a crucial role in the interaction between the circadian clock and the activation of microglia/macrophages into their pro-inflammatory state, which has important implications in the control of neuroinflammation.

The circadian clock ticks in organoids

Organoids are self-organizing in vitro 3D cultures that are histologically similar to a variety of human organs. A recent study by Rosselot et al (2021) shows that mature intestinal organoids possess species-specific circadian clocks similar to their respective in vivo context, suggesting organoids as promising platforms to study circadian medicine.

BMAL1/FOXA2-induced rhythmic fluctuations in IL-6 contribute to nocturnal asthma attacks

The circadian clock is closely associated with inflammatory reactions. Increased inflammatory cytokine levels have been detected in the airways of nocturnal asthma. However, the mechanisms that contribute to the nocturnal increase in inflammatory responses and the relationship with circadian clock remain unknown.

Methods

Inflammatory cytokine levels were measured in asthma patients with and without nocturnal symptoms. Allergic airway disease was induced in mice by ovalbumin (OVA), and different periods of light/dark cycles were used to induce circadian rhythm disorders. Serum shock was used to stimulate the rhythmic expression in human bronchial epidermal cells (16HBE). The expression and oscillation of circadian clock genes and inflammatory cytokines in 16HBE cells subjected to brain and muscle ARNT-like protein-1 (BMAL1) and Forkhead Box A2 (FOXA2) knockdown and treatment with a FOXA2 overexpression plasmid were assessed.

Results

Serum IL-6 was found to be significantly higher in asthmatic patients with nocturnal symptoms than those without nocturnal symptoms. The OVA-induced asthma model with a circadian rhythm disorder and 16HBE cells treated with serum shock showed an increase in IL-6 levels and a negative correlation with BMAL1 and FOXA2. The knockdown of BMAL1 resulted in a lower correlation between IL-6 and other rhythm clock genes. Furthermore, knockdown of the BMAL1 and FOXA2 in 16HBE cells reduced the expression and rhythmic fluctuations of IL-6.

Conclusions

Our findings suggest that there are increased IL-6 levels in nocturnal asthma resulting from inhibition of the BMAL1/FOXA2 signalling pathway in airway epithelial cells.

Time restricted feeding modifies leukocyte responsiveness and improves inflammation outcome

Time restricted eating, the dietary approach limiting food intake to a maximal 10-hour period of daytime is considered beneficial in metabolic dysfunctions, such as obesity and diabetes. Rhythm of food intake and parallel changes in serum nutrient levels are also important entrainment signals for the circadian clock, particularly in tissues involved in metabolic regulation. As both the metabolic state and the circadian clock have large impact on immune functions, we investigated in mice whether time restricted feeding (TRF) affects systemic inflammatory potential. TRF slackened the symptoms in K/BxN serum-transfer arthritis, an experimental model of human autoimmune joint inflammation. Compared to ad libitum conditions TRF reduced the expression of inflammatory mediators in visceral adipose tissue, an integrator and coordinator of metabolic and inflammatory processes. Furthermore, TRF strengthened the oscillation of peripheral leukocyte counts and alongside decreased the pool of both marginated and tissue leukocytes. Our data suggest that the altered leukocyte distribution in TRF mice is related to the attenuated expression of adhesion molecules on the surface of neutrophils and monocytes. We propose that TRF modifies both rhythm and inflammatory potential of leukocytes which contribute to the milder reactivity of the immune system and therefore time-restricted eating could serve as an effective complementary tool in the therapy of autoinflammatory processes.

Circadian rhythms in psoriasis and the potential of chronotherapy in psoriasis management

The physiology and pathology of the skin are influenced by daily oscillations driven by a master clock located in the brain, and peripheral clocks in individual cells. The pathogenesis of psoriasis is circadian-rhythmic, with flares of disease and symptoms such as itch typically being worse in the evening/night-time. Patients with psoriasis have changes in circadian oscillations of blood pressure and heart rate, supporting wider circadian disruption. In addition, shift work, a circadian misalignment challenge, is associated with psoriasis. These features may be due to underlying circadian control of key effector elements known to be relevant in psoriasis such as cell cycle, proliferation, apoptosis and inflammation. Indeed, peripheral clock pathology may lead to hyperproliferation of keratinocytes in the basal layers, insufficient apoptosis of differentiating keratinocytes in psoriatic epidermis, dysregulation of skin-resident and migratory immune cells and modulation of angiogenesis through circadian oscillation of vascular endothelial growth factor A (VEGF-A) in epidermal keratinocytes. Chronotherapeutic effects of topical steroids and topical vitamin D analogues have been reported, suggesting that knowledge of circadian phase may improve the efficacy, and therapeutic index of treatments for psoriasis. In this viewpoint essay, we review the current literature on circadian disruption in psoriasis. We explore the hypothesis that psoriasis is circadian-driven. We also suggest that investigation of the circadian components specific to psoriasis and that the in vitro investigation of circadian regulation of psoriasis will contribute to the development of a novel chronotherapeutic treatment strategy for personalised psoriasis management. We also propose that circadian oscillations of VEGF-A offer an opportunity to enhance the efficacy and tolerability of a novel anti-VEGF-A therapeutic approach, through the timed delivery of anti-VEGF-A drugs.

Performance of Contactless Respiratory Rate Monitoring by Albus HomeTM, an Automated System for Nocturnal Monitoring at Home: A Validation Study

Respiratory rate (RR) is a clinically important predictor of cardio-respiratory deteriorations. The mainstay of clinical measurement comprises the manual counting of chest movements, which is variable between clinicians and limited to sporadic readings. Emerging solutions are limited by poor adherence and acceptability or are not clinically validated. Albus Home^TM is a contactless and automated bedside system for nocturnal respiratory monitoring that overcomes these limitations. This study aimed to validate the accuracy of Albus Home compared to gold standards in real-world sleeping environments. Participants undertook overnight monitoring simultaneously using Albus Home and gold-standard polygraphy with thoraco-abdominal respiratory effort belts (SomnomedicsEU). Reference RR readings were obtained by clinician-count of polygraphy data. For both the Albus system and reference, RRs were measured in 30-s segments, reported as breaths/minute, and compared. Accuracy was defined as the percentage of RRs from the Albus system within ±2 breaths/minute of reference counts. Across a diverse validation set of 32 participants, the mean accuracy exceeded 98% and was maintained across different participant characteristics. In a Bland-Altman analysis, Albus RRs had strong agreement with reference mean differences and the limits of agreement of -0.4 and ±1.2 breaths/minute, respectively. Albus Home is a contactless yet accurate system for automated respiratory monitoring. Validated against gold -standard methods, it enables long-term, reliable nocturnal monitoring without patient burden.

The Role of Circadian Clock Genes in Critical Illness: The Potential Role of Translational Clock Gene Therapies for Targeting Inflammation, Mitochondrial Function, and Muscle Mass in Intensive Care

The Earth's 24-h planetary rotation, with predictable light and heat cycles, has driven profound evolutionary adaptation, with prominent impacts on physiological mechanisms important for surviving critical illness. Pathways of interest include inflammation, mitochondrial function, energy metabolism, hypoxic signaling, apoptosis, and defenses against reactive oxygen species. Regulation of these by the cellular circadian clock (BMAL-1 and its network) has an important influence on pulmonary inflammation; ventilator-associated lung injury; septic shock; brain injury, including vasospasm; and overall mortality in both animals and humans. Whether it is cytokines, the inflammasome, or mitochondrial biogenesis, circadian medicine represents exciting opportunities for translational therapy in intensive care, which is currently lacking. Circadian medicine also represents a link to metabolic determinants of outcome, such as diabetes and cardiovascular disease. More than ever, we are appreciating the problem of circadian desynchrony in intensive care. This review explores the rationale and evidence for the importance of the circadian clock in surviving critical illness.

The effect of fasting on spirometry indices and respiratory symptoms in asthmatic patients

Introduction: Ramadan can alter the course of diseases by changing nutrition patterns, sleep habits, and medication-taking schedules. There are some concerns that patients with asthma may be affected by these alterations during Ramadan and experience deterioration of their symptoms. This study aimed to investigate the effect of fasting in Ramadan on the severity of the disease and spirometric parameters in patients with asthma.

Methods: An overall 120 patients with moderate to severe asthma were investigated during Ramadan and categorized into two groups of fasting (60 cases) and non-fasting (60 cases) groups. Patients underwent spirometry before and after Ramadan and asthma control status was also assessed. The parameters measured in spirometry were compared in each group before and after Ramadan and also between the two groups.

Results: Spirometric measurements including forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), peak expiratory flow (PEF), and FEV1/FVC were not significantly different before and after Ramadan in both groups of fasting and non-fasting patients. Furthermore, there was no significant difference between the two groups in terms of these spirometric parameters changes from baseline. Nevertheless, FEV1 change in the fasting group was significantly higher than that in the non-fasting group (1.46±5.37 vs. -0.13±3.08, respectively; P=0.040).

Conclusion: The results of this study demonstrated that fasting has no significant effect on the severity of asthma and spirometric findings in patients with moderate to severe asthma. Therefore, fasting during Ramadan can be considered safe for patients with asthma.

Longitudinal passive cough monitoring and its implications for detecting changes in clinical status

Research question

What is the impact of the duration of cough monitoring on its accuracy in detecting changes in the cough frequency?

Materials and methods

This is a statistical analysis of a prospective cohort study. Participants were recruited in the city of Pamplona (Northern Spain), and their cough frequency was passively monitored using smartphone-based acoustic artificial intelligence software. Differences in cough frequency were compared using a one-tailed Mann-Whitney U test and a randomisation routine to simulate 24-h monitoring.

Results

616 participants were monitored for an aggregated duration of over 9 person-years and registered 62 325 coughs. This empiric analysis found that an individual's cough patterns are stochastic, following a binomial distribution. When compared to continuous monitoring, limiting observation to 24 h can lead to inaccurate estimates of change in cough frequency, particularly in persons with low or small changes in rate.

Interpretation

Detecting changes in an individual's rate of coughing is complicated by significant stochastic variability within and between days. Assessing change based solely on intermittent sampling, including 24-h, can be misleading. This is particularly problematic in detecting small changes in individuals who have a low rate and/or high variance in cough pattern.

Heterogeneous Condition of Asthmatic Children Patients: A Narrative Review

Currently, asthma represents the most common chronic disorder in children, showing an increasingly consistent burden worldwide. Childhood asthma, similar to what happens in adults, is a diversified disease with a great variability of phenotypes, according to genetic predisposition of patients, age, severity of symptoms, grading of risk, and comorbidities, and cannot be considered a singular well-defined disorder, but rather a uniquely assorted disorder with variable presentations throughout childhood. Despite several developments occurring in recent years in pediatric asthma, above all, in the management of the disease, some essential areas, such as the improvement of pediatric asthma outcomes, remain a hot topic. Most treatments of the type 2 (T2) target phenotype of asthma, in which IL-4, IL-5, and IL-13 modulate the central signals of inflammatory reactions. Although, there may be an unresolved need to identify new biomarkers used as predictors to improve patient stratification using disease systems and to aid in the selection of treatments. Moreover, we are globally facing many dramatic challenges, including climate change and the SARS-CoV2 pandemic, which have a considerable impact on children and adolescent asthma. Preventive strategies, including allergen immunotherapy and microbiome evaluation, and targeted therapeutic strategies are strongly needed in this population. Finally, the impact of asthma on sleep disorders has been reviewed.

Circadian rhythms in immunity and host-parasite interactions

The mammalian immune system adheres to a 24 h circadian schedule, exhibiting daily rhythmic patterns in homeostatic immune processes, such as immune cell trafficking, as well as the inflammatory response to infection. These diurnal rhythms are driven by endogenous molecular clocks within immune cells which are hierarchically coordinated by a light-entrained central clock in the suprachiasmatic nucleus of the hypothalamus and responsive to local rhythmic cues including temperature, hormones and feeding time. Circadian control of immunity may enable animals to anticipate daily pathogenic threat from parasites and gate the magnitude of the immune response, potentially enhancing fitness. However, parasites also strive for optimum fitness and some may have co-evolved to benefit from host circadian timing mechanisms, possibly via the parasites' own intrinsic molecular clocks. In this review, we summarize the current knowledge surrounding the influence of the circadian clock on the mammalian immune system and the host-parasitic interaction. We also discuss the potential for chronotherapeutic strategies in the treatment of parasitic diseases.

Indacaterol acetate/glycopyrronium bromide/mometasone furoate: a combination therapy for asthma

Abstract:

Despite the wide range of available therapies, asthma remains uncontrolled in 40–65% of patients for a number of different reasons. Treatment with an inhaled corticosteroid (ICS) is recommended in the Global Initiative for Asthma 2021 report for patients across all asthma severities, with treatment options combining an ICS with a long-acting β2-agonist (LABA) or a LABA and a long-acting muscarinic antagonist (LAMA), depending on disease severity. Based on this, the availability of single inhaler fixed-dose ICS/LABA/LAMA combination is a major need in asthma management. Indacaterol acetate/glycopyrronium bromide/mometasone furoate has been developed as a once-daily inhaled asthma treatment that combines an ICS (mometasone furoate), a LABA (indacaterol acetate) and a LAMA (glycopyrronium bromide) in a formulation delivered using the dry powder inhaler Breezhaler®, for patients with uncontrolled asthma on medium- or high-dose ICS/LABA. This article provides an overview of the different and complementary mechanisms of action, and the clinical effectiveness of the monocomponents of the indacaterol/glycopyrronium/mometasone furoate fixed combination, and highlights the benefits of using the three agents in combination in patients with moderate and severe asthma.

Circadian clocks' interactions with oxygen sensing and signalling

In mammals, physiology and metabolism are shaped both by immediate and anticipatory responses to environmental changes through the myriad of molecular mechanisms. Whilst the former is mostly mediated through different acute signalling pathways the latter is primarily orchestrated by the circadian clock. Oxygen is vital for life and as such mammals have evolved different mechanisms to cope with changes in oxygen levels. It is widely accepted that oxygen sensing through the HIF-1 signalling pathway is paramount for the acute response to changes in oxygen levels. Circadian clocks are molecular oscillators that control 24 hours rhythms in various aspects of physiology and behaviour. Evidence emerging in recent years points towards pervasive molecular and functional interactions between these two pathways on multiple levels. Daily oscillations in oxygen levels are circadian clock-controlled and can reset the clock through HIF-1. Furthermore, the circadian clock appears to modulate the hypoxic response. We review herein the literature related to the crosstalk between the circadian clockwork and the oxygen-signalling pathway in mammals at the molecular and physiological level both under normal and pathologic conditions.

Validation of the LEOSound® monitor for standardized detection of wheezing and cough in children

BACKGROUND

A hallmark of many respiratory conditions is the presence of nocturnal symptoms. Nevertheless, especially in children there is currently still a huge diagnostic gap in detecting nighttime symptoms, which leads to an underestimation of the frequency in clinical practise.

METHODS

We evaluated the clinical applicability and determined the formal test characteristics of the LEOSound ® system, a device for digital long-time recording and automated detection of acoustic airway events. Airway sounds were recorded overnight in 115 children and adolescents (1-17 years) with and without respiratory conditions. The automated classification for "cough" and "wheezing" was subsequently validated against the manual acoustic reassessment by an expert physician.

RESULTS

The general acceptance was good across all age groups and a technically successful recording was obtained in 98 children, corresponding to 92,976 sound epochs (à 30 s) or a total of 774 h of lung sounds. We found a sensitivity of 89% and a specificity of 99% for the automated detection of cough. For detection of wheezing, sensitivity and specificity were both 98%. The cough index and the wheeze index (events per hour) of individual patients showed a strong positive correlation (cough: r_S  = 0.85, wheeze: r_S  = 0.95) and a sufficient agreement of the two assessment methods in the Bland-Altman analysis.

CONCLUSION

Our data show that the LEOSound® is a suitable device for standardized detection of cough and wheezing and hence a promising diagnostic tool to detect nocturnal respiratory symptoms, especially in children. However, a validation process to reduce false positive classifications is essential in clinical routine use.

Recent Advances in Chronotherapy Targeting Respiratory Diseases

Respiratory diseases contribute to a significant percentage of mortality and morbidity worldwide. The circadian rhythm is a natural biological process where our bodily functions align with the 24 h oscillation (sleep-wake cycle) process and are controlled by the circadian clock protein/gene. Disruption of the circadian rhythm could alter normal lung function. Chronotherapy is a type of therapy provided at specific time intervals based on an individual's circadian rhythm. This would allow the drug to show optimum action, and thereby modulate its pharmacokinetics to lessen unwanted or unintended effects. In this review, we deliberated on the recent advances employed in chrono-targeted therapeutics for chronic respiratory diseases.

Circadian disruption and human health

Circadian disruption is pervasive and can occur at multiple organizational levels, contributing to poor health outcomes at individual and population levels. Evidence points to a bidirectional relationship, in that circadian disruption increases disease severity and many diseases can disrupt circadian rhythms. Importantly, circadian disruption can increase the risk for the expression and development of neurologic, psychiatric, cardiometabolic, and immune disorders. Thus, harnessing the rich findings from preclinical and translational research in circadian biology to enhance health via circadian-based approaches represents a unique opportunity for personalized/precision medicine and overall societal well-being. In this Review, we discuss the implications of circadian disruption for human health using a bench-to-bedside approach. Evidence from preclinical and translational science is applied to a clinical and population-based approach. Given the broad implications of circadian regulation for human health, this Review focuses its discussion on selected examples in neurologic, psychiatric, metabolic, cardiovascular, allergic, and immunologic disorders that highlight the interrelatedness between circadian disruption and human disease and the potential of circadian-based interventions, such as bright light therapy and exogenous melatonin, as well as chronotherapy to improve and/or modify disease outcomes.

The endogenous circadian system worsens asthma at night independent of sleep and other daily behavioral or environmental cycles

Asthma often worsens at night. To determine if the endogenous circadian system contributes to the nocturnal worsening of asthma, independent of sleep and other behavioral and environmental day/night cycles, we studied patients with asthma (without steroid use) over 3 wk in an ambulatory setting (with combined circadian, environmental, and behavioral effects) and across the circadian cycle in two complementary laboratory protocols performed in dim light, which separated circadian from environmental and behavioral effects: 1) a 38-h "constant routine," with continuous wakefulness, constant posture, 2-hourly isocaloric snacks, and 2) a 196-h "forced desynchrony" incorporating seven identical recurring 28-h sleep/wake cycles with all behaviors evenly scheduled across the circadian cycle. Indices of pulmonary function varied across the day in the ambulatory setting, and both laboratory protocols revealed significant circadian rhythms, with lowest function during the biological night, around 4:00 AM, uncovering a nocturnal exacerbation of asthma usually unnoticed or hidden by the presence of sleep. We also discovered a circadian rhythm in symptom-based rescue bronchodilator use (β2-adrenergic agonist inhaler) whereby inhaler use was four times more likely during the circadian night than day. There were additive influences on asthma from the circadian system plus sleep and other behavioral or environmental effects. Individuals with the lowest average pulmonary function tended to have the largest daily circadian variations and the largest behavioral cycle effects on asthma. When sleep was modeled to occur at night, the summed circadian, behavioral/environmental cycle effects almost perfectly matched the ambulatory data. Thus, the circadian system contributes to the common nocturnal worsening of asthma, implying that internal biological time should be considered for optimal therapy.

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.

Asthma diagnosis: into the fourth dimension

Asthma is the most common chronic respiratory disease in the UK; however, the misdiagnosis rate is substantial. The lack of consistency in national guidelines and the paucity of data on the performance of diagnostic algorithms compound the challenges in asthma diagnosis. Asthma is a highly rhythmic disease, characterised by diurnal variability in clinical symptoms and pathogenesis. Asthma also varies day to day, seasonally and from year to year. As much as it is a hallmark for asthma, this variability also poses significant challenges to asthma diagnosis. Almost all established asthma diagnostic tools demonstrate diurnal variation, yet few are performed with standardised timing of measurements. The dichotomous interpretation of diagnostic outcomes using fixed cut-off values may further limit the accuracy of the tests, particularly when diurnal variability straddles cut-off values within a day, and careful interpretation beyond the 'positive' and 'negative' outcome is needed. The day-to-day and more long-term variations are less predictable and it is unclear whether performing asthma diagnostic tests during asymptomatic periods may influence diagnostic sensitivities. With the evolution of asthma diagnostic tools, home monitoring and digital apps, novel strategies are needed to bridge these gaps in knowledge, and circadian variability should be considered during the standardisation process. This review summarises the biological mechanisms of circadian rhythms in asthma and highlights novel data on the significance of time (the fourth dimension) in asthma diagnosis.

Passive siRNA transfection method for gene knockdown in air-liquid interface airway epithelial cell cultures

Differentiation of human bronchial epithelial cells (HBEs) in air-liquid interface (ALI) cultures recapitulates organotypic modeling of the in vivo environment. Although ALI cultures are invaluable for studying the respiratory epithelial barrier, loss-of-function studies are limited by potentially cytotoxic reagents in classical transfection methods, the length of the differentiation protocol, and the number of primary epithelial cell passages. Here, we present the efficacy and use of a simple method for small interfering RNA (siRNA) transfection of normal HBEs (NHBEs) in ALI cultures that does not require potentially cytotoxic transfection reagents and does not detrimentally alter the physiology or morphology of NHBEs during the differentiation process. This transfection protocol introduces a reproducible and efficient method for loss-of-function studies in HBE ALI cultures that can be leveraged for modeling the respiratory system and airway diseases.

Bronchodilating effects of a new beclometasone dipropionate plus formoterol fumarate formulation via pressurized metered-dose inhaler in asthmatic children: a double-blind, randomized, cross-over clinical study

A new pediatric fixed combination of beclometasone dipropionate (BDP) 50 μg and formoterol fumarate (FF) 6 μg via pressurized metered-dose inhaler (pMDI) (CHF1535, Chiesi, Italy) was investigated. In a double-blind, randomized, placebo-controlled, cross-over study, a single CHF1535 administration using AeroChamber Plus™ spacer device (2 actuations, total dose BDP 100 μg/FF 12 μg) was compared to the same pMDI free combination in 56 asthmatic children aged ≥ 5 and < 12 years. Primary efficacy variable was forced expiratory volume during the first second (FEV₁) area under the curve corrected by time over 12 h following morning dose (AUC_0-12h). Further CHF1535 doses (50 μg/6 μg, 100 μg/12 μg, and 200 μg/24 μg) were also explored. Adverse events, electrocardiogram, and vital signs were monitored for safety. CHF1535 was non-inferior to free combination [adjusted mean difference (95% CI) 0.004 L (- 0.050, 0.041] with lower confidence limit greater than the limit set at 0.1 L. FEV₁ AUC_0-12h of each CHF1535 dose vs placebo were 0.037 L (p = 0.160), 0.119 L (p < 0.001), and 0.094 (p < 0.001) for 50/6, 100/12, and 200/24, respectively. No safety signals were found.Conclusion: CHF1535 was as effective as free combination BDP/FF, with a trend towards a dose-related response. All treatments were safe.Trial registration: ClinicalTrials.gov ID: NCT01584492 What is Known: •Inhaled pressurized metered-dose solutions (pMDI) are the preferred treatment for pediatric asthma. •Combination therapy of inhaled corticosteroids and long-acting β₂- agonists is a well-established approach to control airway inflammation and airway obstruction also in pediatric patients. What is New: •A novel pediatric pMDI fixed combination of beclomethasone dipropionate 50 μg and formoterol fumarate 6 μg (CHF 1535) was non-inferior to the free combination at the same dose in pulmonary function over the 12-h post-dose period in asthmatic children, with trend towards a dose-related response.

Lung function improvements following inhaled indacaterol/glycopyrronium/mometasone furoate are independent of dosing time in asthma patients: a randomised trial

Once-daily asthma treatment should prevent night-time deterioration, irrespective of the time of dosing. IND/GLY/MF, a fixed-dose combination of inhaled indacaterol acetate (IND, long-acting β₂-agonist (LABA)), glycopyrronium bromide (GLY, long-acting muscarinic antagonist) and mometasone furoate (MF, inhaled corticosteroid (ICS)) delivered by Breezhaler, is indicated in adult asthma patients inadequately controlled on LABA/ICS.

A randomised, double-blind, placebo-controlled, three-period, crossover, phase II study was performed to investigate the bronchodilator effect of IND/GLY/MF (150/50/80 μg) dosed morning and evening versus placebo in patients with mild-moderate asthma. The primary end-point was weighted mean forced expiratory volume in 1 s (FEV₁) over 24 h following 14 days of IND/GLY/MF dosed a.m. and p.m. versus placebo. Secondary end-points included the effect of dosing time on peak expiratory flow (PEF) and safety/tolerability.

Of 37 randomised patients (age 18–72 years; 21 male, 16 female) 34 completed all three treatment periods. At screening, median (range) pre-bronchodilator FEV₁ was 75.8% (60–96%). Patients were using stable low- (83.8%) or medium-dose (16.2%) ICS. Morning and evening dosing of IND/GLY/MF improved FEV₁ (area under the curve from 0 to 24 h) by 610 mL (90% CI 538–681 mL) and 615 mL (90% CI 544–687 mL), respectively, versus placebo. Mean PEF over 14 days increased by 70.7 L·min⁻¹ (90% CI 60.5–80.9 L·min⁻¹) following a.m. dosing, and by 59.7 L·min⁻¹ (90% CI 49.5–69.9 L·min⁻¹) following p.m. dosing of IND/GLY/MF versus placebo. IND/GLY/MF demonstrated a safety profile comparable with placebo.

Once-daily inhaled IND/GLY/MF was well tolerated and provided sustained lung function improvements over 24 h, irrespective of a.m. or p.m. dosing, in patients with mild–moderate asthma.

This randomised study found single-inhaler indacaterol/glycopyrronium/mometasone furoate improved respiratory parameters FEV₁ and PEF in asthma patients, and showed similar efficacy when taken once daily in the morning or eveninghttps://bit.ly/3fH0I1K

Cellular clocks in hyperoxia effects on [Ca2+]i regulation in developing human airway smooth muscle

Supplemental O2 (hyperoxia) is necessary for preterm infant survival but is associated with development of bronchial airway hyperreactivity and childhood asthma. Understanding early mechanisms that link hyperoxia to altered airway structure and function are key to developing advanced therapies. We previously showed that even moderate hyperoxia (50% O2) enhances intracellular calcium ([Ca2+]i) and proliferation of human fetal airway smooth muscle (fASM), thereby facilitating bronchoconstriction and remodeling. Here, we introduce cellular clock biology as a novel mechanism linking early oxygen exposure to airway biology. Peripheral, intracellular clocks are a network of transcription-translation feedback loops that produce circadian oscillations with downstream targets highly relevant to airway function and asthma. Premature infants suffer circadian disruption whereas entrainment strategies improve outcomes, highlighting the need to understand relationships between clocks and developing airways. We hypothesized that hyperoxia impacts clock function in fASM and that the clock can be leveraged to attenuate deleterious effects of O2 on the developing airway. We report that human fASM express core clock machinery (PER1, PER2, CRY1, ARNTL/BMAL1, CLOCK) that is responsive to dexamethasone (Dex) and altered by O2. Disruption of the clock via siRNA-mediated PER1 or ARNTL knockdown alters store-operated calcium entry (SOCE) and [Ca2+]i response to histamine in hyperoxia. Effects of O2 on [Ca2+]i are rescued by driving expression of clock proteins, via effects on the Ca2+ channels IP3R and Orai1. These data reveal a functional fASM clock that modulates [Ca2+]i regulation, particularly in hyperoxia. Harnessing clock biology may be a novel therapeutic consideration for neonatal airway diseases following prematurity.

Cell Autonomous Circadian Systems and Their Relation to Inflammation

All living beings on earth have an important mechanism of 24-h periodicity, which controls their physiology, metabolism, and behavior. In humans, 24-h periodicity is regulated by the superchiasmatic nucleus (SCN) through external and environmental cues. Peripheral organs demonstrate circadian rhythms and circadian clock functions, and these are also observed in cultured cell lines. Every cell contains a CLOCK: BMAL1 loop for the generation of circadian rhythms. In this review, we focused on cell autonomous circadian rhythms in immune cells, the inflammatory diseases caused by disruption of circadian rhythms in hormones, and the role of clock genes in inflammatory diseases.

Investigation of treatment-time differences in colistin-induced nephrotoxicity in Wistar rats

Colistin-induced nephrotoxicity (CIN) occurs in up to 60% of patients, and this has restricted its clinical use. In view of its efficacy amidst the rising challenge of infections caused by multidrug-resistant bacteria, current studies are focusing on ways to ameliorate colistin-induced nephrotoxicity. This study investigated treatment-time differences in colistin-induced nephrotoxicity in Wistar rats. A dose of 600,000 IU/Kg/day of colistimethate sodium (CMS) was administered to male Wistar rats to induce nephrotoxicity; the rats tolerated the higher dose for the treatment duration with higher mean values of serum creatinine, urea, and malondialdehyde compared to the group that received 450,000 IU/Kg/day CMS (p ≤ 0.05). Four groups (n = 8/group) of rats received intraperitoneal (i.p.) injections of 600,000 IU/Kg/day CMS each at four equally spaced circadian times (00:00, 06:00, 12:00, and 18:00 h) to determine the time of administration with least renal toxicity. Biomarkers of oxidative stress and renal toxicity were measured and kidney histology studied after the treatments. The results showed a 24-h pattern in nephrotoxicity from CIN, and that treatment during the activity time period (dark phase) caused lowest CIN. Histological findings supported this finding, with photomicrographs consistently showing more pronounced features of CIN in the groups treated during time frame that coincided with the rest phase in rats (12:00 and 18:00).

Therapeutics on the clock: Circadian medicine in the treatment of chronic inflammatory diseases

The circadian clock is a collection of endogenous oscillators with a periodicity of ~ 24 h. Recently, our understanding of circadian rhythms and their regulation at genomic and physiologic scales has grown significantly. Knowledge of the circadian influence on biological processes has provided new possibilities for novel pharmacological strategies. Directly targeting the biological clock or its downstream targets, and/or using timing as a variable in drug therapy are now important pharmacological considerations. The circadian machinery mediates many aspects of the inflammatory response and, reciprocally, an inflammatory environment can disrupt circadian rhythms. Therefore, intense interest exists in leveraging circadian biology as a means to treat chronic inflammatory diseases such as sepsis, asthma, rheumatoid arthritis, osteoarthritis, and cardiovascular disease, which all display some type of circadian signature. The purpose of this review is to evaluate the crosstalk between circadian rhythms, inflammatory diseases, and their pharmacological treatment. Evidence suggests that carefully rationalized application of chronotherapy strategies - alone or in combination with small molecule modulators of circadian clock components - can improve efficacy and reduce toxicity, thus warranting further investigation and use.

Association of circadian clock TIMELESS variants and expression with asthma risk in children

INTRODUCTION

Bronchial asthma is a chronic respiratory disease characterized by airway inflammation, allergen-induced hypersensitivity and dyspnea. Most asthmatic patients demonstrate oscillations of disease symptoms within 24 hours regulated by circadian clock genes. We hypothesized that these genes may be regulators of childhood asthma risk.

OBJECTIVES

The aim was to investigate whether single-nucleotide polymorphisms (SNPs) in the circadian clock genes are associated with childhood asthma risk. We also aimed to analyze the mRNA level of clock genes in the blood of asthmatic children and NHBE cells stimulated with IL-13.

MATERIALS AND METHODS

Peripheral blood was collected from 165 asthmatic and 138 healthy Polish children. NHBE cells were culture at the air-liquid interface (ALI) with IL-13 as an in vitro model of allergic inflammation. Using TaqMan probes, we genotyped 32 SNPs in: CLOCK, BMAL1, PER3 and TIMELESS. Expression analysis for TIMELESS was performed using real-time PCR with SYBR Green. For haplotype and genotype statistical analysis we used Haploview 4.2 and STATISTICA version 12, respectively. Gene expression analysis was performed in DataAssist v3.01.

RESULTS

We found that three polymorphisms in TIMELESS (rs2291739, rs10876890, rs11171856) and two haplotypes (TTTT and CTAC) were associated with asthma risk. We also found significantly decreased expression of TIMELESS in the blood of asthmatic children as compared to the healthy children (P = 0.0289) and in NHBE cells stimulated with IL-13 (P = 0.0302).

CONCLUSIONS

In our study, we showed for the first time that TIMELESS variants and expression may be associated with childhood asthma.

Characterization of immune responses and the lung transcriptome in a murine model of IL-33 challenge

IL-33 induces airway inflammation and hyper-responsiveness in respiratory diseases. Although defined as a therapeutic target, there are limited studies that have comprehensively investigated IL-33-mediated responses in the lungs in vivo. In this study, we characterized immunological and physiological responses induced by intranasal IL-33 challenge, in a mouse model. We identified specific cytokines, IL-4, IL-5, IL-6, IL-10, IP-10 and MIP1-α, that are increased in bronchoalveolar lavage and lung tissues by IL-33. Using transcriptomics (RNA-Seq) we demonstrated that 2279 transcripts were up-regulated and 1378 downregulated (≥ 2-fold, p < 0.01) in lung tissues, in response to IL-33. Bioinformatic interrogation of the RNA-Seq data was used to predict biological pathways and upstream regulators involved in IL-33-mediated responses. We showed that the mRNA and protein of STAT4, a predicted upstream regulator of IL-33-induced transcripts, was significantly enhanced in the lungs following IL-33 challenge. Overall, this study provides specific IL-33-induced molecular targets and endpoints that can be used as a resource for in vivo studies, e.g. in preclinical murine models examining novel interventions to target downstream effects of IL-33.

Innate Rhythms: Clocks at the Center of Monocyte and Macrophage Function

The circadian cycle allows organisms to track external time of day and predict/respond to changes in the external environment. In higher order organisms, circadian rhythmicity is a central feature of innate and adaptive immunity. We focus on the role of the molecular clock and circadian rhythmicity specifically in monocytes and macrophages of the innate immune system. These cells display rhythmicity in their internal functions, such as metabolism and inflammatory mediator production as well as their external functions in pathogen sensing, phagocytosis, and migration. These inflammatory mediators are of clinical interest as many are therapeutic targets in inflammatory disease such as cardiovascular disease, diabetes, and rheumatoid arthritis. Moreover, circadian rhythm disruption is closely linked with increased prevalence of these conditions. Therefore, understanding the mechanisms by which circadian disruption affects monocyte/macrophage function will provide insights into novel therapeutic opportunities for these chronic inflammatory diseases.

Day and Night Control of COPD and Role of Pharmacotherapy: A Review

The topic of 24-hour management of COPD is related to day-to-night symptoms management, specific follow-up and patients' adherence to therapy. COPD symptoms strongly vary during day and night, being worse in the night and early morning. This variability is not always adequately considered in the trials. Night-time symptoms are predictive of higher mortality and more frequent exacerbations; therefore, they should be a target of therapy. During night-time, in COPD patients the supine position is responsible for a different thoracic physiology; moreover, during some sleep phases the vagal stimulation determines increased bronchial secretions, increased blood flow in the bronchial circulation (enhancing inflammation) and increased airway resistance (broncho-motor tone). Moreover, in COPD patients the circadian rhythm may be impaired. The role of pharmacotherapy in this regard is still poorly investigated. Symptoms can be grossly differentiated according to the different phenotypes of the disease: wheezing recalls asthma, while dyspnea is strongly related to emphysema (dynamic hyperinflation) or obstructive bronchiolitis (secretions). Those symptoms may be different targets of therapy. In this regard, GOLD recommendations for the first time introduced the concept of phenotype distinction suggesting the use of inhaled corticosteroids (ICS) particularly when an asthmatic pattern or eosiophilic inflammations are present, and hypothesized different approaches to target symptoms (ie, dyspnea) or exacerbations. Pharmacotherapy should be evaluated and possibly directed on the basis of circadian variations, for instance, supporting the use of twice-daily rapid-action bronchodilators and evening dose of ICS. Recommendations on day and night symptoms monitoring strategies and choice of the specific drug according to patient's profile are still not systematically investigated or established. This review is the summary of an advisory board on the topic "24-hour control of COPD and role of pharmacotherapy", held by five pulmonologists, experts in respiratory pathophysiology, pharmacology and sleep medicine.

"Severe-controlled" asthma 4 years later: is it still controlled?

BACKGROUND

Controlled severe asthma is based on needing regular medication and 4 markers of good asthma control. This study reevaluated a community sample defined 4 years earlier as "severe-controlled" based on electronic medical records of medications dispensed over 12 months.

OBJECTIVES

Determine the current extent of clinically-controlled asthma and asthma-related quality-of-life among patients previously considered "severe-controlled".

METHODS

69 patients considered "severe-controlled" 4 years earlier answered a questionnaire that included the asthma control test (ACT), demographics, education, comorbidities, medications, asthma-related healthcare utilization, atopy history, environmental exposures, and follow-up. Patients underwent spirometry, eosinophil count, total IgE, and skin-prick testing for airborne allergens.

RESULTS

Ninety-seven percent reported using combined inhalers (ICS + LABA) regularly. Only 4% visited the ER and none was hospitalized in the last year. Average predicted FEV₁ was 80%. Average ACT score was 19; 51% reported recurrent heartburn, 46% night awakenings and 70% recurrent rhinitis. Skin-prick testing was positive in 72%, average IgE was 376 IU/ml. Eosinophil counts were ≥300/ml in 42% and ≥400/ml in 25%. ACT < 20 was strongly related to recurrent heartburn. Formal education was related to ACT ≥ 20 (p = 0.045) and perception of good asthma control the previous month (p < 0.001). Eosinophil count, recurrent heartburn, total IgE, and recurrent rhinitis were interrelated.

CONCLUSIONS

Among severe asthmatics, good drug compliance, low use of relievers and low rates of exacerbations do not necessarily reflect asthma-related quality-of-life and optimal control. We urge physicians and HMOs to address asthma control in terms of quality-of-life based on validated questionnaires, and offer all patients asthma education; perhaps more to those with low formal education.

Regulatory T cells confer a circadian signature on inflammatory arthritis

The circadian clock is an intrinsic oscillator that imparts 24 h rhythms on immunity. This clock drives rhythmic repression of inflammatory arthritis during the night in mice, but mechanisms underlying this effect are not clear. Here we show that the amplitude of intrinsic oscillators within macrophages and neutrophils is limited by the chronic inflammatory environment, suggesting that rhythms in inflammatory mediators might not be a direct consequence of intrinsic clocks. Anti-inflammatory regulatory T (Treg) cells within the joints show diurnal variation, with numbers peaking during the nadir of inflammation. Furthermore, the anti-inflammatory action of Treg cells on innate immune cells contributes to the night-time repression of inflammation. Treg cells do not seem to have intrinsic circadian oscillators, suggesting that rhythmic function might be a consequence of external signals. These data support a model in which non-rhythmic Treg cells are driven to rhythmic activity by systemic signals to confer a circadian signature to chronic arthritis.

Targeting REV-ERBα for therapeutic purposes: promises and challenges

REV-ERBα (NR1D1) is a circadian clock component that functions as a transcriptional repressor. Due to its role in direct modulation of metabolic genes, REV-ERBα is regarded as an integrator of cell metabolism with circadian clock. Accordingly, REV-ERBα is first proposed as a drug target for treating sleep disorders and metabolic syndromes (e.g., dyslipidaemia, hyperglycaemia and obesity). Recent years of studies uncover a rather broad role of REV-ERBα in pathological conditions including local inflammatory diseases, heart failure and cancers. Moreover, REV-ERBα is involved in regulation of circadian drug metabolism that has implications in chronopharmacology. In the meantime, recent years have witnessed discovery of an array of new REV-ERBα ligands most of which have pharmacological activities in vivo. In this article, we review the regulatory role of REV-ERBα in various types of diseases and discuss the underlying mechanisms. We also describe the newly discovered ligands and the old ones together with their targeting potential. Despite well-established pharmacological effects of REV-ERBα ligands in animals (preclinical studies), no progress has been made regarding their translation to clinical trials. This implies certain challenges associated with drug development of REV-ERBα ligands. In particular, we discuss the potential challenges related to drug safety (or adverse effects) and bioavailability. For new drug development, it is advocated that REV-ERBα should be targeted to treat local diseases and a targeting drug should be locally distributed, avoiding the adverse effects on other tissues.

Circadian rhythms in innate immunity and stress responses

Circadian clocks are a common feature of life on our planet, allowing physiology and behaviour to be adapted to recurrent environmental fluctuation. There is now compelling evidence that disturbance of circadian coherence can severely undermine mental and physical health, as well as exacerbate pre-existing pathology. Common molecular design principles underpin the generation of cellular circadian rhythms across the kingdoms, and in animals, the genetic components are extremely well conserved. In mammals, the circadian timing mechanism is present in most cell types and establishes local cycles of gene expression and metabolic activity. These distributed tissue clocks are normally synchronized by a central pacemaker, the suprachiasmatic nuclei (SCN), located in the hypothalamus. Nevertheless, most clocks of the body remain responsive to non-SCN-derived hormonal and metabolic cues (for example, re-alignment of liver clocks to altered meal patterning). It has been demonstrated that the clock is an influential regulator of energy metabolism, allowing key pathways to be tuned across the 24-hr cycle as metabolic requirements fluctuate. Furthermore, clock components, including Cryptochrome and Rev-Erb proteins, have been identified as essential modulators of the innate immune system and inflammatory responses. Studies have also revealed that these proteins regulate glucocorticoid receptor function, a major drug target and crucial regulator of inflammation and metabolism.

Clockwork allergy: How the circadian clock underpins allergic reactions

Allergic disease is characterized by marked day-night changes in the clinical symptoms and laboratory parameters of allergy. Recent reports suggest that the circadian clock, which drives a biological rhythm with a periodicity of approximately 24 hours in behavior and physiology, underpins a time of day-dependent variation in allergic reactions. New studies also suggest that disruption of clock activity not only influences temporal variation but can also enhance the severity of allergic reactions and even increase susceptibility to allergic disease. These findings suggest that the circadian clock is a potent regulator of allergic reactions that plays more than a simple circadian timekeeping role in allergy. A better understanding of these processes will provide new insight into previously unknown aspects of the biology of allergies and can lead to the application of clock modifiers to treat allergic disease. Finally, this area of research provides a novel opportunity to consider how modern lifestyles in the developed world are changing the clinical manifestations of allergy as our society quickly transforms into a circadian rhythm-disrupted society in which sleeping, working, and eating habits are out of sync with endogenous circadian rhythmicity. Such findings might reveal lifestyle interventions that enable us to better control allergic disease.

Circadian variability in airways characteristics: A spirometric study

Background: Chronic obstructive pulmonary disease (COPD) and Asthma patients exhibit exacerbation of symptoms in night hours and early morning. Temporal variability in airway caliber have been reported in past using peak expiratory flow rate which represents large airways caliber, while in COPD and Asthma, smaller airways are particularly affected. We studied circadian variability of airway caliber using Forced Expiratory Volume in the First Second (FEV1) and Mid Expiratory Flow rate. Methods: Male volunteers (18-26 years), having similar daily routine were recruited. Spirometry was performed at 5: 00, 8:00, 11:00, 14:00, 17:00, 20:00 and 23:00 h. Data from 104 subjects was analyzed for diurnal variability parameters viz., amplitude percent mean and standard deviation percent of mean. For circadian rhythm Cosinor curve was fitted and rhythm characteristics in terms of MESOR, Amplitude and Acrophase were determined. Results: Repeated measures ANOVA revealed significant differences in spirometric parameters measured at different time points during the day. In general, spirometric parameters follow a sinusoidal pattern and exhibit minimum values during night hours and maximum values during day time. FEV1 Cosinor rhythm was significant in 31% of subjects (Zero amplitude test). The distribution of acrophase revealed interindividual differences in chronophenotypes. Variability was minimum for FEV1% and maximum for FEF75 suggesting dynamic interplay of airway geometry and neuro-chemical influences. Conclusion: The presence of different chronophenotypes in normal subjects suggests that the nocturnal asthma may also be a different phenotype. Availability of portable spirometers and home monitoring thus may be required for ascertaining chronophenotype and tailoring chronotherapeutic interventions.

Toxicogenomic analysis of publicly available transcriptomic data can predict food, drugs, and chemical-induced asthma

Background

: With the increasing incidence of asthma, more attention is focused on the diverse and complex nutritional and environmental triggers of asthma exacerbations. Currently, there are no established risk assessment tools to evaluate asthma triggering potentials of most of the nutritional and environmental triggers encountered by asthmatic patients.

Purpose

 The objective of this study is to devise a reliable workflow, capable of estimating the toxicogenomic effect of such factors on key player genes in asthma pathogenesis.

Methods

Gene expression extracted from publicly available datasets of asthmatic bronchial epithelium were subjected to a comprehensive analysis of differential gene expression to identify significant genes involved in asthma development and progression. The identified genes were subjected to Gene Set Enrichment Analysis using a total of 31,826 gene sets related to chemical, toxins, and drugs to identify common agents that share similar asthma-related targets genes and signaling pathways.

Results

Our analysis identified 225 differentially expressed genes between severe asthmatic and healthy bronchial epithelium. Gene Set Enrichment Analysis of the identified genes showed that they are involved in response to toxic substances and organic cyclic compounds and are targeted by 41 specific diets, plants products, and plants related toxins (eg adenine, arachidonic acid, baicalein, caffeic acid, corilagin, curcumin, ellagic acid, luteolin, microcystin-RR, phytoestrogens, protoporphyrin IX, purpurogallin, rottlerin, and salazinic acid). Moreover, the identified chemicals share interesting inflammation-related pathways like NF-κB.

Conclusion

Our analysis was able to explain and predict the toxicity in terms of stimulating the differentially expressed genes between severe asthmatic and healthy epithelium. Such an approach can pave the way to generate a cost-effective and reliable source for asthma-specific toxigenic reports thus allowing the asthmatic patients, physicians, and medical researchers to be aware of the potential triggering factors with fatal consequences.

Sleep and asthma

PURPOSE OF REVIEW

There is a longstanding recognition of the detrimental effect of poorly controlled asthma on sleep, but recent years have seen a growing interest in how asthma and sleep may interact. This review examines the current evidence of relationships between asthma, sleep and sleep disorders.

RECENT FINDINGS

Poor quality sleep and sleep disturbance is highly prevalent in asthmatic patients, and particularly in those with severe asthma. Impaired sleep quality correlates with worse asthma control and quality of life. Sleep disturbance in asthma may be related to due circadian variation in airway inflammation, but may also be related to specific sleep disorders. Obstructive sleep apnoea (OSA) appears to be significantly more common in asthmatic patients than nonasthmatic patients, and treatment of OSA with continuous positive airway pressure (CPAP) may lead to improved asthma-specific quality of life. Nocturnal CPAP may also be of benefit to asthmatic patients without OSA, potentially because of stretching of airway smooth muscle. Insomnia is also highly prevalent in severe asthma patients, and is associated with a history of poor asthma control and increased healthcare utilization.

SUMMARY

Asthma, sleep and sleep disorders appear to have complex, but significant relationships. Prospective observational and controlled interventional studies are needed to quantify how addressing sleep difficulties may benefit asthma patients.

The effect of diurnal variation in exercise-induced bronchoconstriction

Objective: Exercise-induced bronchoconstriction (EIB) is an acute, transient narrowing of the airway as a result of exercise. Diurnal variation in asthma is well-established, however, few studies have investigated diurnal variability in EIB; no study has used eucapnic voluntary hyperpnea (EVH). The aim of this study was to examine circadian variability in EIB using EVH.Methods: Fourteen recreationally-active males with mild to moderate asthma and nine healthy controls were randomized to first complete either an AM (07:00-08:00) or PM (17:00-18:00) EVH challenge, followed by the alternate test 34 h to 7 days later. The EVH protocol comprised of six-minutes of hyperventilation of a 5% CO₂ gas at a minimum ventilation rate of 21 × FEV₁ min^-1. The primary outcome measure was FEV₁ pre- and post-EVH.Results: We observed no diurnal effect on EIB in the asthma group. The minimum observed post-EVH FEV₁ in the asthma cohort was 3.58 ± 0.95 L in AM and 3.62 ± 0.87 L in PM tests, corresponding to a 15.0 ± 15.3% vs. 14.9 ± 14.7% reduction from baseline, respectively. The asthma group showed similar baseline FEV₁ before AM (4.21 ± 0.79 L) and PM (4.25 ± 0.65 L) tests. No difference was observed in minute ventilation between AM (26.1 ± 3.4 × FEV₁ min^-1) and PM (25.6 ± 3.8 × FEV₁ min^-1) tests for the asthma cohort. Controls displayed no significant changes in FEV₁ or minute ventilation between tests.Conclusions: When baseline pulmonary function is similar, this study suggests that time-of-day has no effect on EIB in mild to moderate asthma.

The Genetics and Genomics of Asthma

Asthma is a common, clinically heterogeneous disease with strong evidence of heritability. Progress in defining the genetic underpinnings of asthma, however, has been slow and hampered by issues of inconsistency. Recent advances in the tools available for analysis-assaying transcription, sequence variation, and epigenetic marks on a genome-wide scale-have substantially altered this landscape. Applications of such approaches are consistent with heterogeneity at the level of causation and specify patterns of commonality with a wide range of alternative disease traits. Looking beyond the individual as the unit of study, advances in technology have also fostered comprehensive analysis of the human microbiome and its varied roles in health and disease. In this article, we consider the implications of these technological advances for our current understanding of the genetics and genomics of asthma.

Dead in the Night: Sleep-Wake and Time-Of-Day Influences on Sudden Unexpected Death in Epilepsy

Sudden unexpected death in epilepsy (SUDEP) is the leading cause of epilepsy-related death in patients with refractory epilepsy. Convergent lines of evidence suggest that SUDEP occurs due to seizure induced perturbation of respiratory, cardiac, and electrocerebral function as well as potential predisposing factors. It is consistently observed that SUDEP happens more during the night and the early hours of the morning. The aim of this review is to discuss evidence from patient cases, clinical studies, and animal research which is pertinent to the nocturnality of SUDEP. There are a number of factors which might contribute to the nighttime predilection of SUDEP. These factors fall into four categories: influences of (1) being unwitnessed, (2) lying prone in bed, (3) sleep-wake state, and (4) circadian rhythms. During the night, seizures are more likely to be unwitnessed; therefore, it is less likely that another person would be able to administer a lifesaving intervention. Patients are more likely to be prone on a bed following a nocturnal seizure. Being prone in the accouterments of a bed during the postictal period might impair breathing and increase SUDEP risk. Sleep typically happens at night and seizures which emerge from sleep might be more dangerous. Lastly, there are circadian changes to physiology during the night which might facilitate SUDEP. These possible explanations for the nocturnality of SUDEP are not mutually exclusive. The increased rate of SUDEP during the night is likely multifactorial involving both situational factors, such as being without a witness and prone, and physiological changes due to the influence of sleep and circadian rhythms. Understanding the causal elements in the nocturnality of SUDEP may be critical to the development of effective preventive countermeasures.

Molecular Actions of PPARα in Lipid Metabolism and Inflammation

Peroxisome proliferator-activated receptor α (PPARα) is a nuclear receptor of clinical interest as a drug target in various metabolic disorders. PPARα also exhibits marked anti-inflammatory capacities. The first-generation PPARα agonists, the fibrates, have however been hampered by drug-drug interaction issues, statin drop-in, and ill-designed cardiovascular intervention trials. Notwithstanding, understanding the molecular mechanisms by which PPARα works will enable control of its activities as a drug target for metabolic diseases with an underlying inflammatory component. Given its role in reshaping the immune system, the full potential of this nuclear receptor subtype as a versatile drug target with high plasticity becomes increasingly clear, and a novel generation of agonists may pave the way for novel fields of applications.