Simulated Night Shift Disrupts Circadian Rhythms of Immune Functions in Humans

Chrononutrition in Critical Illness

Circadian rhythms in humans are biological rhythms that regulate various physiological processes within a 24-hour time frame. Critical illness can disrupt the circadian rhythm, as can environmental and clinical factors, including altered light exposure, organ replacement therapies, disrupted sleep-wake cycles, noise, continuous enteral feeding, immobility, and therapeutic interventions. Nonpharmacological interventions, controlling the ICU environment, and pharmacological treatments are among the treatment strategies for circadian disruption. Nutrition establishes biological rhythms in metabolically active peripheral tissues and organs through appropriate synchronization with endocrine signals. Therefore, adhering to a feeding schedule based on the biological clock, a concept known as "chrononutrition," appears to be vitally important for regulating peripheral clocks. Chrononutritional approaches, such as intermittent enteral feeding that includes overnight fasting and consideration of macronutrient composition in enteral solutions, could potentially restore circadian health by resetting peripheral clocks. However, due to the lack of evidence, further studies on the effect of chrononutrition on clinical outcomes in critical illness are needed. The purpose of this review was to discuss the role of chrononutrition in regulating biological rhythms in critical illness, and its impact on clinical outcomes.

Time of day and circadian disruption influence host response and parasite growth in a mouse model of cerebral malaria

Malaria is a disease caused by infection with parasite Plasmodium spp. We studied the circadian regulation of host responses to the parasite, in a mouse model of cerebral malaria. The course of the disease was markedly affected by time of infection, with decreased parasitemia and increased inflammation upon infection in the middle of the night. At this time, there were fewer reticulocytes, which are target cells of the parasites. We next investigated the effects of desynchronization of host clocks on the infection: after 10 weeks of recurrent jet lags, mice showed decreased parasite growth and lack of parasite load rhythmicity, paralleled by a loss of glucose rhythm. Accordingly, disrupting host metabolic rhythms impacted parasite load rhythmicity. In summary, our findings of a circadian modulation of malaria parasite growth and infection shed light on aspects of the disease relevant to human malaria and could contribute to new therapeutic or prophylactic measures.

Circadian Effects on Vascular Immunopathologies

Circadian rhythms exert a profound impact on most aspects of mammalian physiology, including the immune and cardiovascular systems. Leukocytes engage in time-of-day-dependent interactions with the vasculature, facilitating the emigration to and the immune surveillance of tissues. This review provides an overview of circadian control of immune-vascular interactions in both the steady state and cardiovascular diseases such as atherosclerosis and infarction. Circadian rhythms impact both the immune and vascular facets of these interactions, primarily through the regulation of chemoattractant and adhesion molecules on immune and endothelial cells. Misaligned light conditions disrupt this rhythm, generally exacerbating atherosclerosis and infarction. In cardiovascular diseases, distinct circadian clock genes, while functioning as part of an integrated circadian system, can have proinflammatory or anti-inflammatory effects on these immune-vascular interactions. Here, we discuss the mechanisms and relevance of circadian rhythms in vascular immunopathologies.

Day-to-day deviations in sleep parameters and biological aging: Findings from the NHANES 2011-2014

OBJECTIVES

The majority of the previous research has focused on the impact of average sleep parameters on longevity. In this study, we aimed to investigate the associations of day-to-day deviations in sleep parameters with biological ages among 6052 adults participating in the 2011-2014 waves of the US National Health and Nutrition Examination Survey.

METHODS

Sleep parameters, including sleep duration, efficiency, midpoint, and day-to-day deviations in sleep parameters, including standard deviation of sleep duration (sleep variability), standard deviation of sleep midpoint (sleep irregularity), catch-up sleep, and social jetlag, were obtained from 4 to 7 days of 24-h accelerometer recording. We used physiological data to compute measurements of biological aging according to 3 published algorithms: PhenoAge, Klemera-Doubal method Biological Age, and homeostatic dysregulation.

RESULTS

After adjustment of multiple covariates, we observed that all parameters of day-to-day deviations in sleep were significantly associated with biological aging with larger sleep variability, larger sleep irregularity, more catch-up sleep, and more social jetlag linked with more advanced biological aging. The significant associations of sleep irregularity, catch-up sleep, and social jetlag with biological aging indices remained even after adjustment for sleep duration, efficiency, and midpoint.

CONCLUSION

In this study, we found that day-to-day deviations in sleep parameters are independently associated with biological aging in US general population. Since day-to-day deviation in sleep is a modifiable behavioral factor, our finding suggests that intervention aiming at increasing regularity in sleep patterns may be a novel approach for extending a healthy life span.

Neuroimmune Mechanisms of Opioid Use Disorder and Recovery: Translatability to Human Studies, and Future Research Directions

Opioid use disorder (OUD) is a major current cause of morbidity and mortality. Long-term exposure to short-acting opioids (MOP-r agonists such as heroin or fentanyl) results in complex pathophysiological changes to neuroimmune and neuroinflammatory functions, affected in part by peripheral mechanisms (e.g., cytokines in blood), and by neuroendocrine systems such as the hypothalamic-pituitary-adrenal (HPA) stress axis. There are important findings from preclinical models, but their role in the trajectory and outcomes of OUD in humans is not well understood. The goal of this narrative review is to examine available data on immune and inflammatory functions in persons with OUD, and to identify major areas for future research. Peripheral blood biomarker studies revealed a pro-inflammatory state in persons with OUD in withdrawal or early abstinence, consistent with available postmortem brain studies (which show glial activation) and diffusion tensor imaging studies (indicating white matter disruptions), with gradual abstinence-associated recovery. The mechanistic roles of these neuroimmune and neuroinflammatory changes in the trajectory of OUD (including recovery and medication management) cannot be examined practically with postmortem data. Collection of longitudinal data in larger-scale human cohorts would allow examination of these mechanisms associated with OUD stage and progression. Given the heterogeneity in presentation of OUD, a precision medicine approach integrating multi-omic peripheral biomarkers and comprehensive phenotyping, including neuroimaging, can be beneficial in risk stratification, and individually optimized selection of interventions for individuals who will benefit, and assessments under refractory therapy.

The Effects of Shift Work on the Immune System: A Narrative Review

Working a shift work schedule has been hypothesized to have negative effects on health. One such described consequence is altered immune response and increased risk of infections. Former reviews have concluded that more knowledge is needed to determine how shift work affects the immune system. Since the last review focusing on this subject was published in 2016, new insight has emerged. We performed a search of the topic in PubMed, Scopus and Embase, identifying papers published after 2016, finding a total of 13 new studies. The articles identified showed inconsistent effect on immune cells, cytokines, circadian rhythms, self-reported infections, and vaccine response as a result of working a shift schedule. Current evidence suggests working shifts influence the immune system, however the clinical relevance and the mechanism behind this potential association remains elusive. Further studies need to include longitudinal design and objective measures of shift work and immune response.

Time-restricted feeding attenuates hypercholesterolaemia and atherosclerosis development during circadian disturbance in APOE∗3-Leiden.CETP mice

BACKGROUND

Circadian disturbance (CD) is the consequence of a mismatch between endogenous circadian rhythms, behaviour, and/or environmental cycles, and frequently occurs during shift work. Shift work has been associated with elevated risk for atherosclerotic cardiovascular disease (asCVD) in humans, but evidence for the effectiveness of prevention strategies is lacking.

METHODS

Here, we applied time-restricted feeding (TRF) as a strategy to counteract atherosclerosis development during CD in female APOE∗3-Leiden.CETP mice, a well-established model for humanized lipoprotein metabolism. Control groups were subjected to a fixed 12:12 h light-dark cycle, while CD groups were subjected to 6-h phase advancement every 3 days. Groups had either ad libitum (AL) access to food or were subjected to TRF with restricted food access to the dark phase.

FINDINGS

TRF did not prevent the increase in the relative abundance of circulating inflammatory monocytes and elevation of (postprandial) plasma triglycerides during CD. Nonetheless, TRF reduced atherosclerotic lesion size and prevented an elevation in macrophage content of atherosclerotic lesions during CD, while it increased the relative abundance of anti-inflammatory monocytes, prevented activation of T cells, and lowered plasma total cholesterol levels and markers of hepatic cholesterol synthesis. These effects were independent of total food intake.

INTERPRETATION

We propose that time restricted eating could be a promising strategy for the primary prevention of asCVD risk in shift workers, which warrants future study in humans.

FUNDING

This work was funded by the Novo Nordisk Foundation, the Netherlands Ministry of Social Affairs and Employment, Amsterdam Cardiovascular Sciences, and the Dutch Heart Foundation.

Beyond sleep: A multidimensional model of chronotype

Chronotype can be defined as an expression or proxy for circadian rhythms of varied mechanisms, for example in body temperature, cortisol secretion, cognitive functions, eating and sleeping patterns. It is influenced by a range of internal (e.g., genetics) and external factors (e.g., light exposure), and has implications for health and well-being. Here, we present a critical review and synthesis of existing models of chronotype. Our observations reveal that most existing models and, as a consequence, associated measures of chronotype have focused solely or primarily on the sleep dimension, and typically have not incorporated social and environmental influences on chronotype. We propose a multidimensional model of chronotype, integrating individual (biological and psychological), environmental and social factors that appear to interact to determine an individual's true chronotype with potential feedback loops between these factors. This model could be beneficial not only from a basic science perspective but also in the context of understanding health and clinical implications of certain chronotypes as well as designing preventive and therapeutic approaches for related illnesses.

Exploring Clinical Trials to Manage Firefighters' Sleep Quality: A PRISMA Compliant Systematic Review

Sleep research has grown over the past decades and investigators are deeply involved in studying sleep and its impact on human health and body regulation. Despite the understanding that insufficient sleep is strongly linked to the development of several disorders, unsatisfactory sleep exposes health and safety to innumerous risks. The present study aims to review and analyze the main results of clinical trials, registered at ClinicalTrials.gov and ICTRT databases, and developed construct strategies to improve sleep quality on firefighters and enhance professionals' sleep and health conditions. The protocol was registered in PROSPERO under number CRD42022334719. Trials registered between first registry and 2022 were included. We retrieved 11 registered clinical trials; seven met eligibility criteria and were included in the review. A relation between sleep disorders, shift work, and occupational health problems was found, and retrieved trials showed that sleep education programs can improve sleep quality and sleep hygiene. Science has already recognized sleep's importance for metabolic functioning and survivorship. Nevertheless, it continues to play a major role in discovering methods to diminish the problems faced. Strategies contemplating sleep education, or intervention, should be presented to fire services to tackle this problem and promote healthier and safer environments.

Sleep and circadian rhythm disruption alters the lung transcriptome to predispose to viral infection

Sleep and circadian rhythm disruption (SCRD), as encountered during shift work, increases the risk of respiratory viral infection including SARS-CoV-2. However, the mechanism(s) underpinning higher rates of respiratory viral infection following SCRD remain poorly characterized. To address this, we investigated the effects of acute sleep deprivation on the mouse lung transcriptome. Here we show that sleep deprivation profoundly alters the transcriptional landscape of the lung, causing the suppression of both innate and adaptive immune systems, disrupting the circadian clock, and activating genes implicated in SARS-CoV-2 replication, thereby generating a lung environment that could promote viral infection and associated disease pathogenesis. Our study provides a mechanistic explanation of how SCRD increases the risk of respiratory viral infections including SARS-CoV-2 and highlights possible therapeutic avenues for the prevention and treatment of respiratory viral infection.

The Effect of Night Shifts on 24-h Rhythms in the Urinary Metabolome of Police Officers on a Rotating Work Schedule

Shift workers face an increased risk of metabolic health problems, but the direct metabolic response to working nights is not fully understood. The aim of this study was to investigate the effect of night shifts on the 24-h urinary metabolome of shift workers. Eleven police officers working rotating shifts completed two 24-h laboratory visits that took place before and after they worked 7 consecutive nights. Sleep and meals were scheduled on a day schedule in the first visit and then on a night schedule (i.e., sleep and meals shifted by approximately 12 h) in the second visit. Targeted metabolomic analysis was performed on urine samples collected throughout these laboratory visits. Differential rhythmicity analysis was used to compare 24-h rhythms in urinary metabolites in both conditions. Our results show that on the day schedule, 24-h rhythms are present in the urinary levels of the majority of metabolites, but that this is significantly reduced on the night schedule, partly due to loss of organic acid rhythmicity. Furthermore, misalignment of 24-h metabolite rhythms with the shifted behavioral cycles in the night schedule was observed in more than half of the metabolites that were rhythmic in both conditions (all acylcarnitines). These results show that working nights alters the daily rhythms of the urinary metabolome in rotating shift workers, with the most notable impact observed for acylcarnitines and organic acids, 2 metabolite classes involved in mitochondrial function. Further research is warranted to study how these changes relate to the increased metabolic risks associated with shift work.

Associations between sampling characteristics, nutritional supplemental taking and the SARS-CoV-2 infection onset in a cohort of Italian nurses

Background: The aim of the present study was to analyze any relations existed between sampling characteristics and the onset of the SARS-CoV-2 infection, also by considering the number of times that it occurred in a cohort of Italian nurses interviewed. Additionally, by considering the nutritional supplemental taking, this research wanted to assess any differences both in the onset and in the number of times which the infection occurred among participants. Method: An observational cohort study was carried out thorough all Italian nurses by advertising the questionnaire through some professional internet pages. Results: Work typology (p=0.021), ward Covid-19 (p=0.002) and regular meal assumption (p=0.019) significantly associated to the onset of the SARS-CoV-2 infection. Most of nurses who contracted the SARS-CoV-2 infection worked during the night shift (53.7%), 44.3% worked in a no-Covid-19 ward and 53% declared to have a regular meals’ assumption. Ward typology significantly associated to the times of the SARS-CoV-2 onset (p=0.003), as most of nurses who contracted almost one time the SARS-CoV-2 infection were employed in a no-Covid-19 ward (55.5%) and 54.1% of them declared to have a regular meals’ assumption. The onset of the Sars-CoV-2 infection seemed to be more present in the most part of the sample collect. Conclusion: The present study could be considered as pilot in this sense and also more studies will be performed in order to better relate the function of supplemental food intakes with a better functioning of the immune system.

Circadian Disruption and Consequences on Innate Immunity and Inflammatory Response

Circadian rhythms control almost all aspects of physiology and behavior, allowing temporal synchrony of these processes between each other, as well as with the external environment. In the immune system, daily rhythms of leukocyte functions can determine the strength of the immune response, thereby regulating the efficiency of defense mechanisms to cope with infections or tissue injury. The natural light/dark cycle is the prominent synchronizing agent perceived by the circadian clock, but this role of light is highly compromised by irregular working schedules and unintentional exposure to artificial light at night (ALAN). The primary concern is disrupted circadian control of important physiological processes, underlying potential links to adverse health effects. Here, we first discuss the immune consequences of genetic circadian disruption induced by mutation or deletion of specific clock genes. Next, we evaluate experimental research into the effects of disruptive light/dark regimes, particularly light-phase shifts, dim ALAN, and constant light on the innate immune mechanisms under steady state and acute inflammation, and in the pathogenesis of common lifestyle diseases. We suggest that a better understanding of the mechanisms by which circadian disruption influences immune status can be of importance in the search for strategies to minimize the negative consequences of chronodisruption on health.

Immune disruptions and night shift work in hospital healthcare professionals: The intricate effects of social jet-lag and sleep debt

Objectives

We aimed to examine the effects of circadian and sleep rhythm disruptions on immune biomarkers among hospital healthcare professionals working night shifts and rotating day shifts.

Methods

Hospital nurses working either as permanent night shifters (n=95) or as day shifters rotating between morning and afternoon shifts (n=96) kept a daily diary on their sleep and work schedules over a full working week. Blood samples were collected at the beginning and end of the last shift during the week, and participants were categorized into three groups based on work shift: morning shift (39 day shifters sampled at 7:00 and 14:00), afternoon shift (57 day shifters sampled at 14:00 and 21:00), and night shift (95 night shifters sampled at 21:00 and 7:00). Circulating blood counts in immune cells, interleukin-6 and C-reactive protein concentrations as well as total sleep time per 24 hours during work days (TST24w) and free days (TST24f), sleep debt (TST24f - TST24w) and social jet-lag (a behavioral proxy of circadian misalignment) were assessed.

Results

Compared with day shifters, night shifters had shorter sleep duration (TST24w=5.4 ± 1.4h), greater sleep debt (3.2 ± 1.4 h) and social jet-lag (6.7 ± 2.4 h). Variations of immune biomarkers concentrations were consistent with the expected diurnal variations among day shifters (i.e., low level in the morning, increase during the day, peak value in the evening). By contrast, in night shifters, blood concentrations of total lymphocytes, T-helper cells, cytotoxic T-cells, memory B-cells and interleukin-6 were lower at 21:00, increased during the night, and reached higher values at 7:00. Multivariate analyses ruled out significant impact of TST24w, sleep debt, and social jet-lag on immune biomarkers concentrations among day shifters. In contrast, among night shifters, multivariate analyses indicated a combined effect of total sleep time (TST24w), sleep debt and social jet-lag for total lymphocytes and T-helper cells but only a social jet-lag effect for interleukin-6 and a single total sleep time effect for neutrophil and B-Cells.

Conclusions

Altogether, our results point to intricate response patterns of immune rhythms to circadian misalignment and sleep debt in night shifters. Specifically, these altered pattern expressions of immune cells may increase vulnerability to infections and reduce vaccination efficiency in night workers.

Integrative bioinformatics analysis to identify the effects of circadian rhythm on Crohn’s disease

Background: Crohn’s disease (CD) is a multifactorial inflammatory bowel disease characterized by complex aberrant autoimmune disorders. Currently, the involvement of the circadian rhythm in the pathogenesis of CD is unknown.

Methods: Bulk and single-cell RNA-seq data and associated clinical data from patients with CD were downloaded from the Gene Expression Omnibus (GEO). Single-sample gene set enrichment analysis was performed to calculate the enrichment score (ES) of circadian rhythm-related genes. Differential expression analysis was used to identify differentially expressed genes. Functional enrichment analysis was used to explore potential disease mechanisms. CIBERSORT was used to estimate immune cell abundance. Single-cell RNA-seq data were analyzed using the R package “Seurat.”

Results: The ES of circadian rhythm-related genes was lower in the CD tissue than in the normal tissue. Ubiquitin-specific protease 2 (USP2), a circadian rhythm-related gene, was identified as a potential modulator of CD pathogenesis. USP2 expression was reduced in CD and was associated with disease severity. Moreover, the analysis of bulk RNA-seq and single-cell RNA-seq data showed that monocyte and neutrophil abundance was elevated in CD and was negatively correlated with USP2 expression. It should be noted that USP2 expression in acinar cells was negatively correlated with monocyte and neutrophil abundance. Functional enrichment analysis revealed several canonical pathways to be enriched in CD, including the interleukin-17 signaling pathway, tumor necrosis factor signaling pathway, cytokine–cytokine receptor interaction, toll-like receptor signaling pathway, and nod-like receptor signaling pathway.

Conclusion: Aberrant expression of circadian rhythm-related genes is correlated with CD pathogenesis. USP2 might be related to crosstalk among the different cell types in CD. These findings provide insights into future chronotherapy for CD.

Disruption of cellular immune response among male rotating night shift workers in Spain– The HORMONIT study

Introduction

Preliminary studies suggest that night shift work is associated with a desynchronization of rhythmic immune markers, possibly explaining the increased risk of infection, cardiometabolic disorders, and cancer in shift workers.

Methods

This study included 51 male rotating shift workers from a car industry in Barcelona, Spain, sampled twice toward the end of a 3-week night shift (22:00-06:00 h) and a 3-week day shift (06:00-14:00 h) rotation. We collected four blood samples per worker, at the start and end of each shift. We measured 27 cytokines, chemokines and growth factors in plasma samples by luminex using the Cytokine Human Magnetic 30-Plex Panel LHC6003M and applied linear mixed models to examine within-person associations between shift work and analytes’ concentrations, comparing samples taken at 06:00 h on a day and night shift. We also conducted a factor analysis using analyte concentrations from all 4 time points for each individual to identify common factors and determine if these factors were altered by shift work.

Results

We observed lower levels of 15 analytes in the night shift compared to the day shift including cytokines (pro-inflammatory TNF-α, IL-2R; anti-inflammatory IL1-RA; Th1 IL-2, Th2 IL-4 and Th17 Il-17), chemokines (IP-10, MIP-1α, MIP-1β, RANTES) and growth factors (EGF, G-CSF, HGF, VEGF, FGF). In a factor analysis, three factors were identified. The main factor (Factor 1), explaining 57% of the variance and including IL-1β, IL-12, IL-15, MIP-1α, MIP-1β, EGF and FGF; and another factor (Factor 3) explaining 10% of the variance and including the Th1 cytokine IL-12, were inversely associated with the night shift (coefficient: -0.17, 95%CI -0.32 to -0.01 and coefficient: -0.22, 95%CI -0.38, -0.06, for Factors 1 and 3, respectively). Our results indicate that night shift disrupts the levels of several immune markers, which could contribute to the increased risk of infections and cancer reported in night shift workers.

Conclusion

Night shift is associated with disruption of multiple immune response pathways.

The Psychological Impact and Influencing Factors during Different Waves of COVID-19 Pandemic on Healthcare Workers in Central Taiwan

BACKGROUND

This study aims to explore differences of psychological impact and influencing factors that affected Taiwanese healthcare workers (HCW) during the first and second wave of COVID-19.

METHODS

a cross sectional survey of first-line HCW during November 2021 to February 2022: 270 paper questionnaires were issued and the valid response rate was 86% (231). For statistical analysis, descriptive statistics, Pearson correlation, and multivariate linear regression were used.

RESULTS

regardless of the wave of the pandemic, nearly 70% of HCW had anxiety, nearly 60% felt depressed, half of them suffered from insomnia, and one in three felt insufficient social support, which means a high level of loneliness. With an increased number of infected patients during the second wave, HCW felt significant changes of workload and schedule, with higher concern over risk of infection, and these factors induced higher levels of anxiety, but they manifested better satisfaction over public health policies and information provided by hospitals and governments. Changes of working schedules or duties positively relate to levels of anxiety and insomnia. The risk of infection causes anxiety, depression, and insomnia. Workplace relationships significantly relate to depression and loneliness. A negative family support causes an adverse psychological impact.

CONCLUSIONS

the pandemic has a negative psychological impact on HCW. Early recognition of significant influencing factors, providing psychological support and therapy, are helpful strategies for reducing the adverse psychological effects.

Night-shift work is associated with increased susceptibility to SARS-CoV-2 infection

Night-shift workers experience disturbances of their circadian rhythm and sleep, which may make them more susceptible to infectious diseases. Therefore, we studied whether night-shift workers are at higher risk of testing positive for SARS-CoV-2 infection than day workers. In this prospective study, data were used from 20 questionnaire rounds of the Dutch Lifelines COVID-19 cohort that was initiated in March 2020. In the different questionnaire rounds, 2285 night-shift workers and 23,766 day workers reported whether they had tested positive for SARS-CoV-2. Cox proportional hazards regression models adjusted for demographic, work, and health covariates were used to compare SARS-CoV-2 incidence between night-shift and day workers. From March 2020-January 2021, 3.4% of night-shift workers and 2.2% of day workers reported to have tested positive for SARS-CoV-2 (p < .001). After adjustment for covariates, night-shift workers had a 37% higher risk of testing positive for SARS-CoV-2 (hazard ratio: 1.37, 95% confidence interval: 1.05-1.77). In this study, we show that night-shift workers were more likely to test positive for SARS-CoV-2 than day workers, which adds to the growing evidence that night-shift work may influence the complex processes involved in infection susceptibility. Further mechanistic insight is needed to understand the relation between night-shift work and (SARS-CoV-2) infection susceptibility.

Disrupting circadian rhythms promotes cancer-induced inflammation in mice

Disruption of circadian rhythms occurs in rotating shift-work, jetlag, and in individuals with irregular sleep schedules. Circadian disruption is known to alter inflammatory responses and impair immune function. However, there is limited understanding of how circadian disruption modulates cancer-induced inflammation. Inflammation is a hallmark of cancer and is linked to worse prognosis and impaired brain function in cancer patients. Here, we investigated the effect of circadian disruption on cancer-induced inflammation in an orthotopic breast cancer model. Using a validated chronic jetlag protocol that advances the light-cycle by 8 ​h every 2 days to disrupt circadian rhythms, we found that circadian disruption alters cancer-induced inflammation in a tissue-specific manner, increasing inflammation in the body and brain while decreasing inflammation within the tumor tissue. Circadian disruption did not affect inflammation in mice without tumors, suggesting that the impact of circadian disruption may be particularly detrimental in the context of underlying inflammatory conditions, such as cancer. Importantly, circadian disruption did not affect tumor burden, suggesting that increased inflammation was not a result of increased cancer progression. Overall, these findings identify the importance of healthy circadian rhythms for limiting cancer-induced inflammation.

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Circadian disruption enhances cancer-induced inflammation in the body and brain.

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The profile of inflammatory cytokines altered by circadian disruption is tissue specific.

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Changes in inflammatory profiles by circadian ​disruption are not due to enhanced tumor burden.

Night shift work characteristics are associated with several elevated metabolic risk factors and immune cell counts in a cross-sectional study

Night shift work is associated with increased health risks. Here we examined the association of metabolic risk factors and immune cell counts, with both night shift work and particular characteristics thereof: frequency, duration and consecutive night shifts. We performed a cross-sectional study using data from 10,201 non-shift workers and 1062 night shift workers of the Lifelines Cohort study. Linear regression analyses, adjusted for demographic, lifestyle and occupational factors, were used to study associations of night shift work characteristics with metabolic risk factors and immune cell counts. Night shift workers had an increased BMI, waist circumference and immune cell counts compared to non-shift workers. This was especially seen in night shift workers who had a higher frequency of night shifts per month (≥ 5: BMI: B = 0.81 kg/m² (95%-CI = 0.43–1.10); waist circumference: B = 1.58 cm (95%-Cl = 0.34–1.71; leukocytes: B = 0.19 × 10⁹ cells/L (95%-CI = 0.04–0.34 × 10⁹)) and worked more consecutive night shifts (> 3: BMI: B = 0.92 kg/m² (95%-CI = 0.41–1.43); waist circumference: B = 1.85 cm (95%-Cl = 0.45–3.24); leukocytes: B = 0.32 × 10⁹ cells/L (95%-CI = 0.09–0.55 × 10⁹)). This association was less pronounced in long-term night shift workers (≥ 20 years). Our findings provide evidence for the association between night shift work characteristics and BMI, waist circumference and leukocytes (including, monocytes, lymphocytes, and basophil granulocytes).

Potential effects of shift work on skin autoimmune diseases

Shift work is associated with systemic chronic inflammation, impaired host and tumor defense and dysregulated immune responses to harmless antigens such as allergens or auto-antigens. Thus, shift workers are at higher risk to develop a systemic autoimmune disease and circadian disruption with sleep impairment seem to be the key underlying mechanisms. Presumably, disturbances of the sleep-wake cycle also drive skin-specific autoimmune diseases, but epidemiological and experimental evidence so far is scarce. This review summarizes the effects of shift work, circadian misalignment, poor sleep, and the effect of potential hormonal mediators such as stress mediators or melatonin on skin barrier functions and on innate and adaptive skin immunity. Human studies as well as animal models were considered. We will also address advantages and potential pitfalls in animal models of shift work, and possible confounders that could drive skin autoimmune diseases in shift workers such as adverse lifestyle habits and psychosocial influences. Finally, we will outline feasible countermeasures that may reduce the risk of systemic and skin autoimmunity in shift workers, as well as treatment options and highlight outstanding questions that should be addressed in future studies.

Shift Work Predicts Increases in Lipopolysaccharide-Binding Protein, Interleukin-10, and Leukocyte Counts in a Cross-Sectional Study of Healthy Volunteers Carrying Low-Grade Systemic Inflammation

The disruption of inflammatory responses is a potential mechanism behind the harmful effects of shift work and is associated with increased risk of hypertension, stroke, obesity, diabetes, and cancer. These responses are linked to the proliferation of leukocytes in shift workers, suggesting a systemic signal as a potential mediator. The purpose of this study was to assess the relationship between systemic inflammation, leukocyte counts, and systemic endotoxemia in samples from a diverse cohort of day workers and shift workers. Participants (normothermic and normotensive) were healthy volunteers, non-smoking, and drug- and medication-free. The following outcomes were measured: C-reactive protein, TNF-α, IL-6, IL-1β, IL-10, leukocyte counts (monocytes, lymphocytes, and neutrophils), and lipopolysaccharide-binding protein (LBP). Risk factors that increase systemic inflammation, such as blood pressure, sleep loss, and cortisol, were also assessed. The results indicated that shift workers slept significantly less than day workers and had significantly increased concentrations of all of the cytokines measured as well as plasma cortisol. Regression models found that after controlling for covariates, shift-work exposure predicted the significant increase observed in IL-10, leukocyte counts, and LBP. Our results suggest that acute increases in low-grade systemic endotoxemia are unresolved during chronic shift-work exposure. This ongoing immune challenge may underlie the disrupted inflammatory responses characteristic of shift-work-related pathologies. Systemic endotoxemia may represent a novel target to investigate the early effects of exposure to shift-work schedules.

Circadian rhythms in adaptive immunity and vaccination

Adaptive immunity allows an organism to respond in a specific manner to pathogens and other non-self-agents. Also, cells of the adaptive immune system, such as T and B lymphocytes, can mediate a memory of an encounter with a pathogen, allowing a more efficient response to a future infection. As for other aspects of physiology and of the immune system, the adaptive immune system is regulated by circadian clocks. Consequently, the development, differentiation, and trafficking between tissues of adaptive immune cells have been shown to display daily rhythms. Also, the response of T cells to stimuli (e.g., antigen presentation to T cells by dendritic cells) varies according to a circadian rhythm, due to T cell-intrinsic mechanisms as well as cues from other tissues. The circadian control of adaptive immune response has implications for our understanding of the fight against pathogens as well as auto-immune diseases, but also for vaccination, a preventive measure based on the development of immune memory.

Consistency where it counts: Sleep regularity is associated with circulating white blood cell count in young adults

Background

Sleep irregularity is predictive of poor health outcomes, and particularly those of cardiometabolic origins. The immune system is implicated in the pathogenesis of cardiometabolic diseases, however the relation between sleep regularity and immune cell profile is unclear.

Methods and results

Forty-two healthy young adults (20 ​± ​2 years) completed 14 days of 24-h wrist actigraphy followed by a morning blood sample to evaluate circulating white blood cells (WBC) and subtypes (neutrophils, lymphocytes, monocytes). Sleep regularity was operationalized as the standard deviation (SD) of nightly sleep duration and SD of sleep onset time. Every 60-min increase in sleep duration SD was associated with an estimated 2.7 ​± ​0.60 x10³ ​cells/μL (p<0.001) increase in total WBC count, while every 60-min increase in sleep onset SD was associated with an estimated 2.4 ​± ​0.60 x10³ ​cells/μL (p<0.001) increase in WBCs. Sleep duration SD was also associated with lymphocyte count (11.5 ​± ​3.8 ​cells/μL per 1-min increase, p<0.01), while sleep onset SD was associated with neutrophil (34.7 ​± ​9.8 ​cells/μL per 1-min increase, p<0.01) and monocyte counts (3.0 ​± ​0.9 ​cells/μL per 1-min increase, p<0.01). Sleep regularity metrics remained significantly associated with WBCs in a series of regressions which adjusted for sex, body mass index, resting blood pressure, mean sleep duration, physical activity, dietary sodium, and alcohol consumption.

Conclusions

Unfavorable associations between irregular sleep patterns and circulating immune cells are apparent in young adulthood. These findings contribute to the growing body of evidence suggesting that consistent sleep schedules are an important dimension of sleep and circadian health and may reduce excess chronic disease risk.

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Young adults with irregular sleep patterns have higher total white blood cell count.

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Sleep irregularity is also associated with neutrophils, lymphocytes, and monocytes.

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Associations remain significant after adjusting for several key confounders.

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Consistent sleep patterns may assist in preventing inflammatory-mediated 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.

Nuclear Receptors and Clock Components in Cardiovascular Diseases

Cardiovascular diseases (CVD) are still the first cause of death worldwide. Their main origin is the development of atherosclerotic plaque, which consists in the accumulation of lipids and inflammatory leucocytes within the vascular wall of large vessels. Beyond dyslipidemia, diabetes, obesity, hypertension and smoking, the alteration of circadian rhythms, in shift workers for instance, has recently been recognized as an additional risk factor. Accordingly, targeting a pro-atherogenic pathway at the right time window, namely chronotherapy, has proven its efficiency in reducing plaque progression without affecting healthy tissues in mice, thus providing the rationale of such an approach to treat CVD and to reduce drug side effects. Nuclear receptors are transcriptional factors involved in the control of many physiological processes. Among them, Rev-erbs and RORs control metabolic homeostasis, inflammatory processes and the biological clock. In this review, we discuss the opportunity to dampen atherosclerosis progression by targeting such ligand-activated core clock components in a (chrono-)therapeutic approach in order to treat CVD.

Comparison of Psychological and Physiological Stress in NICU Nurses: Effects of Unit Design and Shift

BACKGROUND

Effects of unit design and shift worked on stress in neonatal intensive care unit (NICU) nurses have not been fully studied.

PURPOSE

To compare stress in NICU nurses who work in single-family room (SFR) or open bay (OBY) units and on nonrotating day or night shift.

METHODS

Full-time registered nurses (RNs) (n = 72) from a 42-bed SFR and a 131-bed OBY NICU participated in this comparative cross-sectional study. The Nurse Stress Scale (NSS) and within-shift repeated salivary cortisol levels were used to measure stress. The relationship between NSS score and salivary cortisol level was examined using multiple linear regression. Salivary cortisol levels of day versus night shift were compared with mixed-effects linear models.

RESULTS

NSS scores were similar for SFR and OBY units (P = .672) and day versus night shift (P = .606). Changes in cortisol level over time (P = .764) and final cortisol level (P = .883) for SFR versus OBY were not significantly different after controlling for shift. Salivary cortisol level of day-shift nurses decreased significantly over time compared with night-shift nurses (P < .001). The final cortisol level was significantly higher for night-shift compared with day-shift nurses (P < .001).

IMPLICATIONS FOR PRACTICE

Psychological (NSS) and physiologic (salivary cortisol) stress of NICU nurses is similar in established SFR and OBY units. Cortisol levels are higher at the end of shift in nurses who work night shift and may reflect increased physiologic stress.

IMPLICATIONS FOR RESEARCH

Strategies are needed for reducing stress in NICU nurses who work night shift.

Circadian disturbances, sleep difficulties and the COVID-19 pandemic

The COVID-19 pandemic has imposed extraordinary and unpredictable changes on our lifestyle for an unknown duration. Consequently, core aspects of wellbeing including behavior, emotion, cognition, and social interactions are negatively affected. Sleep and circadian rhythms, with an extensive impact on physiology, behavior, emotion, and cognition are affected too. We provided an updated overview of the impact of the COVID-19 pandemic on circadian rhythms and sleep based on the results of published studies (n = 48) in three sections. First, we focus on circadian misalignment due to the pandemic in the general population (including shift workers, health staff, students) and COVID-19 patients and summarize the most critically contributing factors to circadian misalignment. Next, we address sleep difficulties and poor sleep quality during the pandemic, their contributing factors, rate and prevalence, and their effects on both the general population and COVID-19 patients. Finally, we summarize the currently applied/recommended interventions for aligning circadian rhythms and improving sleep quality in both, the general population, and COVID-19 patients during the pandemic situation. Briefly, circadian misalignment and sleep difficulties are common consequences of the pandemic in the general population (with elderly, students, children, health and night-work shifters as risk groups) and COVID-19 patients. Home confinement and its physiological, circadian, and psychological derivates are central to these difficulties. Symptoms severity, treatment progress, recovery duration, and even diagnosis of COVID-19 patients are considerably affected by circadian and sleep difficulties. Behavioral interventions for normalizing the factors that contribute to circadian and sleep difficulties are helpful.

Associations between sleep duration, shift work, and infectious illness in the United States: Data from the National Health Interview Survey

OBJECTIVE

Insufficient sleep and circadian disruption have been linked to immune system dysregulation. The aim of this study was to examine the associations between self-reported sleep duration and work schedule with reports of head and chest colds among adults 18 years and older in the United States.

METHODS

Associations between self-reported habitual sleep duration and work schedule (regular daytime, regular evening, regular nighttime, rotating, other) with reports head and chest colds in the past 2 weeks were examined using data from the 2010 and 2015 National Health Interview Survey. Adults who slept 7-8 hours or reported a regular daytime work schedule were considered the reference group. Multivariate logistic regressions, incorporating sampling weights, were computed adjusting for sociodemographic and health characteristics.

RESULTS

Analyses revealed in fully adjusted models that compared to 7- 8 hours sleepers, those sleeping 5 or fewer hours were 44% more likely to report a cold (odds ratio [OR] = 1.44, 95% confidence interval [CI] 1.29-1.61) while those sleeping 9 or more hours were 20% more likely (OR = 1.20, 95% CI 1.06-1.36). Participants who reported a rotating work schedule were 20% more likely to report a cold (OR = 1.20, 95% CI 1.07-1.36) than those reporting a regular daytime work schedule.

CONCLUSIONS

Short and long sleep duration, as well as a rotating shift work schedule, were associated with increased reports of head and chest colds in a nationally representative sample of US adults. Sleep and circadian function may serve as relevant targets to reduce susceptibility to infectious illness.

Differential response of diurnal and nocturnal mammals to prolonged altered light-dark cycle: a possible role of mood associated endocrine, inflammatory and antioxidant system

The circadian system maintains internal 24 h oscillation of behavior and physiology, and its misalignment with external light-dark (LD) cycle results in negative health outcomes. In order to elucidate the effect of prolonged constant condition and the differences in the response between nocturnal and diurnal species, we studied the effects of constant light (LL) and constant darkness (DD) on a diurnal (squirrel) and a nocturnal (mouse) rodent species, focusing on the endocrine, inflammatory and antioxidant systems associated with depression-like behavior. Squirrels and mice (n = 10/group) were placed in chronocubicle under 12:12 h LD cycle, LL and DD. After 4 weeks, animals were subjected to sucrose preference test and blood and brain tissues were collected for measuring melatonin, corticosterone, proinflammatory cytokine, tumor necrosis factor-α (TNF-α) and the activity of primary antioxidant enzymes, catalase (CAT) and superoxide dismutase (SOD). The results show that in diurnal squirrels, prolonged constant darkness reduced sucrose preference, CAT, and SOD, increased corticosterone and TNF-α levels, but caused no significant change in the melatonin compared to LD condition. In contrast, in nocturnal mice constant darkness caused no significant changes in sucrose preference and corticosterone levels, increased melatonin, CAT and SOD levels but decreased TNF-α levels. Chronic LL caused a similar response in both squirrels and mice: it decreased sucrose preference, melatonin, CAT and SOD levels but increased corticosterone and TNF-α levels. Together, the study demonstrates differential effects of altered light-dark cycle in a diurnal and a nocturnal rodent on interrelated endocrine, inflammatory and antioxidant systems associated with depression-like behavior, with constant light having adverse effects on both species but constant darkness having a negative effect mainly in the diurnal squirrels.

Impact of Sleep Deprivation on Emotional Regulation and the Immune System of Healthcare Workers as a Risk Factor for COVID 19: Practical Recommendations From a Task Force of the Latin American Association of Sleep Psychology

Healthcare workers who are on the front line of coronavirus disease 2019 (COVID-19) and are also undergoing shift schedules face long work hours with few pauses, experience desynchronization of their circadian rhythm, and an imbalance between work hours effort and reward in saving lives, resulting in an impact on work capacity, aggravated by the lack of personal protective equipment (PPE), few resources and precarious infrastructure, and fear of contracting the virus and contaminating family members. Some consequences are sleep deprivation, chronic insomnia, stress-related sleep disorders, and post-traumatic stress disorder. These sleep alterations critically affect mental health, precipitating or perpetuating anxiety, stress, and depression, resulting in the inability to regulate positive and negative emotions. Pre-existing sleep disorders are an important risk factor for the development and maintenance of PSTD when individuals are exposed to an important stressor such as a COVID-19 pandemic. At the same time, how an individual regulates the emotion associated with worries during daytime functioning impacts nighttime sleep, precipitating and perpetuating difficulties in sleeping. All of these changes in sleep and emotional regulation also alter the immune system. Sleep deprivation is commonly associated with chronic inflammatory diseases, due to the desynchronizations in circadian rhythms, causing possible psychophysiological disorders and impaired neuroimmune-endocrine homeostasis. From this perspective, we clarify in this article how sleep disorders affect the immune system and emotional regulation, explaining their phenomenological and neurobiological mechanisms, and discussing elements of cognitive and behavioral coping for health professionals to adopt and manage a healthier sleep pattern in the COVID-19 outbreak.

A model-based validation study of postoperative complications with considerations on operative timing

Background

Surgery is a highly technical procedure relying on high mental acuity and manual dexterity. The possibility that surgical outcomes and post-operative complications could be subject to influence by fatigue and/or circadian rhythms in surgeons has been investigated with inconsistent results.

Methods

We conducted a retrospective study to assess the significance of operative timing on classifying surgical complications using an interpretable machine learning approach. We trained various linear, generative as well as tree models on the surgical record data collected from a university-affiliated, tertiary teaching hospital in China by performing parameter tuning using grid search cross-validation for optimizing the F1 score.

Results

The results indicated that XGBoost was the best-performing model overall and its feature importance was shown to provide insight into possible timing-related associations with postoperative complications. We observed that the duration of surgery acted as the strongest indicator, and while surgery initiated at night (between 9 pm and 7 am) also ranked higher on the feature importance scale, it bore less significance than other factors such as the patient's age, gender, and type of surgery performed.

Conclusions

We showed that surgical records could be used to demonstrate that operative timing might affect the occurrence of postoperative complications, but only in a relatively mild way while potentially entangling with multiple factors.

Circadian rhythms: influence on physiology, pharmacology, and therapeutic interventions

Circadian rhythms are ubiquitous phenomena that recur daily in a self-sustaining, entrainable, and oscillatory manner, and orchestrate a wide range of molecular, physiological, and behavioral processes. Circadian clocks are comprised of a hierarchical network of central and peripheral clocks that generate, sustain, and synchronize the circadian rhythms. The functioning of the peripheral clock is regulated by signals from autonomic innervation (from the central clock), endocrine networks, feeding, and other external cues. The critical role played by circadian rhythms in maintaining both systemic and tissue-level homeostasis is well established, and disruption of the rhythm has direct consequence for human health, disorders, and diseases. Circadian oscillations in both pharmacokinetics and pharmacodynamic processes are known to affect efficacy and toxicity of several therapeutic agents. A variety of modeling approaches ranging from empirical to more complex systems modeling approaches have been applied to characterize circadian biology and its influence on drug actions, optimize time of dosing, and identify opportunities for pharmacological modulation of the clock mechanisms and their downstream effects. In this review, we summarize current understanding of circadian rhythms and its influence on physiology, pharmacology, and therapeutic interventions, and discuss the role of chronopharmacometrics in gaining new insights into circadian rhythms and its applications in chronopharmacology.

Proinflammatory Cytokine Dysregulation and Cognitive Dysfunction Among Patients with Remitted Bipolar I and II Disorders

BACKGROUND

Euthymic patients with bipolar disorder reportedly demonstrated increased levels of proinflammatory cytokines and cognitive function deficits. Because uncertain differences exist in cognitive function and proinflammatory cytokines between remitted bipolar I (BD1) and bipolar II (BD2) disorders, we performed this study to further investigate these differences.

METHOD

We enrolled 58 patients with remitted BD1 and 27 with remitted BD2, and matched them for age and sex with 51 controls. Proinflammatory cytokines, including soluble interleukin-6 receptor (sIL-6R), C-reactive protein, and soluble tumor necrosis factor receptor 1 (sTNFR1) were measured, and performance in the Word List Memory Task (WLMT) and Wisconsin Card Sorting Task (WCST) was assessed.

RESULTS

Significantly elevated levels of sTNFR1 were observed among patients with BD1 (p < .001) and BD2 (p = .038) compared with the controls; however, they did not differ between patients with BD1 and BD2 (p =.130). Working memory deficit measured by the WLMT was significantly greater in patients with BD1 (p < .001) and BD2 (p < .05) compared with controls, but did not differ between patients with BD1 and BD2 (p > 0.1). Furthermore, sTNFR1 levels were negatively correlated with cognitive function measured using the WLMT and WCST (all p < .05).

DISCUSSION

Our results showed that euthymic patients with BD1 and BD2 showed similar levels of sTNFR1 and cognitive function (especially working memory) impairments. Further investigation is required to explore whether a common pathophysiology may contribute to the shared inflammatory and cognitive alterations between BD1 and BD2.

Measuring salivary markers of inflammation in health research: A review of methodological considerations and best practices

There is an increasing interest in using saliva to measure inflammatory biomarkers. Compared to blood, saliva is non-invasive, requires a lower biosafety classification, and requires less specialized personnel to collect. As the assessment of inflammation in saliva becomes more popular in psychoneuroimmunology research, the development of gold-standard methodological practices is paramount. This paper reviews different considerations for designing studies to assess salivary measures of inflammation. We review saliva collection procedures, sample storage and processing considerations, assay techniques, flow rate, correspondence with blood-based markers, and potential demographic and health moderators of levels of salivary markers of inflammation. Together, this review highlights critical gaps for future research, including calls for standardization of study protocols, transparent reporting of results, assessing predictive validity of markers of salivary inflammation for disease, and the need for assessment of participants' oral and general health status. Although additional work is needed to elucidate gold standards for study design, measurement, and analysis, salivary markers of inflammation may be a useful tool for understanding oral and peripheral inflammation dynamics non-invasively.

Clocks, Viruses, and Immunity: Lessons for the COVID-19 Pandemic

Circadian rhythms are evolutionarily conserved anticipatory systems that allow the host to prepare and respond to threats in its environment. This article summarizes a European Biological Rhythms Society (EBRS) workshop held in July 2020 to review current knowledge of the interplay between the circadian clock and viral infections to inform therapeutic strategies against SARS-CoV-2 and COVID-19. A large body of work supports the role of the circadian clock in regulating various aspects of viral replication, host responses, and associated pathogenesis. We review the evidence describing the multifaceted role of the circadian clock, spanning host susceptibility, antiviral mechanisms, and host resilience. Finally, we define the most pressing research questions and how our knowledge of chronobiology can inform key translational research priorities.

The Assessment of Circadian Rhythms Within the Immune System

In recent years, circadian rhythms have been observed in many aspects of the immune system, both for the innate immunity (the first line of defense against pathogens) and the adaptive immunity (a more specific set of responses, which lead to immune memory). Here, to illustrate principles to be taken into account when working on circadian rhythms in immunology experiments, two protocols will be presented. The first one aims to analyze immune parameters in blood sampled from human subjects at different times over the day: counts of different cell types among the peripheral blood mononuclear cells and cytokine secretion by monocytes and T cells after ex vivo stimulation. The second protocol describes how to follow the response of CD8⁺ T cells after immunization of mice with antigen presenting cells loaded with a peptide antigen. These two protocols are optimized for circadian experiments, and outcome measures are mainly based on flow cytometry, which allows analysis of different parameters in the same cells.

Nuclear Receptors in the Control of the NLRP3 Inflammasome Pathway

The innate immune system is the first line of defense specialized in the clearing of invaders whether foreign elements like microbes or self-elements that accumulate abnormally including cellular debris. Inflammasomes are master regulators of the innate immune system, especially in macrophages, and are key sensors involved in maintaining cellular health in response to cytolytic pathogens or stress signals. Inflammasomes are cytoplasmic complexes typically composed of a sensor molecule such as NOD-Like Receptors (NLRs), an adaptor protein including ASC and an effector protein such as caspase 1. Upon stimulation, inflammasome complex components associate to promote the cleavage of the pro-caspase 1 into active caspase-1 and the subsequent activation of pro-inflammatory cytokines including IL-18 and IL-1β. Deficiency or overactivation of such important sensors leads to critical diseases including Alzheimer diseases, chronic inflammatory diseases, cancers, acute liver diseases, and cardiometabolic diseases. Inflammasomes are tightly controlled by a two-step activation regulatory process consisting in a priming step, which activates the transcription of inflammasome components, and an activation step which leads to the inflammasome complex formation and the subsequent cleavage of pro-IL1 cytokines. Apart from the NF-κB pathway, nuclear receptors have recently been proposed as additional regulators of this pathway. This review will discuss the role of nuclear receptors in the control of the NLRP3 inflammasome and the putative beneficial effect of new modulators of inflammasomes in the treatment of inflammatory diseases including colitis, fulminant hepatitis, cardiac ischemia-reperfusion and brain diseases.

Changes in Circadian Rhythms Dysregulate Inflammation in Ageing: Focus on Leukocyte Trafficking

Leukocyte trafficking shows strong diurnal rhythmicity and is tightly regulated by circadian rhythms. As we age, leukocyte trafficking becomes dysregulated, contributing to the increased systemic, low-grade, chronic inflammation observed in older adults. Ageing is also associated with diminished circadian outputs and a dysregulation of the circadian rhythm. Despite this, there is little evidence to show the direct impact of age-associated dampening of circadian rhythms on the dysregulation of leukocyte trafficking. Here, we review the core mammalian circadian clock machinery and discuss the changes that occur in this biological system in ageing. In particular, we focus on the changes that occur to leukocyte trafficking rhythmicity with increasing age and consider how this impacts inflammation and the development of immune-mediated inflammatory disorders (IMIDs). We aim to encourage future ageing biology research to include a circadian approach in order to fully elucidate whether age-related circadian changes occur as a by-product of healthy ageing, or if they play a significant role in the development of IMIDs.

Are night shift workers at an increased risk for COVID-19?

Recent data has revealed an association between coronavirus disease-19 (COVID-19) incidence and seasonally regulated androgen sensitivity. This potential relationship between SARS-CoV-2 infection and clock genes, coupled with previously reported effects of night shift work on health, leads us to hypothesize that night shift workers may be at an increased physiological risk of coronavirus disease-19 (COVID-19). Shift work, especially night shift work, has long been associated with several chronic health conditions. The mechanisms that drive these associations are not well understood; however, current literature suggests that the disruption of circadian rhythms may cause downstream hormonal and immune effects that render night shift workers more susceptible to disease. First, circadian rhythms may play a role in the mechanism of viral infection, as viral vaccines administered in the morning elicit greater immune responses than those administered in the afternoon. Next, increased exposure to light at night may inhibit the production of melatonin, which has been observed to enhance DNA repair and shown to upregulate expression of Bmal1, an established inhibitor of herpes simplex virus and influenza. Finally, abnormal immune cell and cytokine levels have been observed following night-shift work. These data suggest that further research is warranted and that high-risk occupations should be taken into consideration as public health policies are introduced and evolve.

Is poor self-rated sleep quality associated with elevated systemic inflammation in healthy older adults?

OBJECTIVE

Examine subjective sleep quality and inflammation among healthy older adults participating in the Australian Research Council Longevity Intervention (ARCLI).

METHODS

Data was taken from a sub-set of 232 participants aged between 60-70 years (M = 65.88 ± SD 4.08 years) who participated in the baseline assessment phase of the Australian Research Council Longevity Intervention (ARCLI) study. Subjective sleep was assessed via the Leeds Sleep Evaluation Questionnaire (LSEQ). Inflammatory markers (TNF-α, IL-1β, IL-6, IL-10, IL-2, IFN-γ, IL-4, hs-CRP) were derived from whole blood. Correlation and multiple regression analyses were used to examine associations between each of the four sleep outcome variables and inflammatory outcomes, examined as a group and following gender stratification.

RESULTS

Difficulties getting to sleep were independently associated with higher IL-2 [F_(1,156) = 4.62, adjusted R² = 0.02, p = 0.03] and IL-1β [F_(1,141) = 8.52, adjusted R² = 0.05, p = 0.004] (whole group). Difficulties getting to sleep were associated with greater IL-1β [males: F_(1,58) = 7.36, adjusted R² = 0.097 p = 0.009; females: F _(1,81) = 4.25, R² = 0.038, p = 0.04], and negatively associated with hs-CRP (women) [F _(1,129) = 4.71, R² = 0.028, p = 0.032].

DISCUSSION

Subjective sleep-onset difficulties are associated with systemic inflammation.

Sickness absenteeism, work performance, and healthcare use due to respiratory infections for shift and non-shift workers

This study aimed to compare sickness absenteeism, work performance, and healthcare use due to respiratory infections, as well as general sickness absenteeism and work performance between shift and non-shift workers. In this study, 589 shift and non-shift workers employed in hospitals were included. For 6 months, participants kept a daily record of their influenza-like illness/acute respiratory infection (ILI/ARI) symptoms using a diary application. After an episode of ILI/ARI symptoms ended, participants (n = 531) were questioned about their sickness absenteeism (occurrence and duration in hours), work performance (on a 10 point scale), and healthcare use during the ILI/ARI episode. At the end of the 6 months follow-up, participants (n = 498) were also asked about general sickness absenteeism and work performance in the past 4 weeks. Mixed-model and regression analyses were used to compare absenteeism, work performance, and healthcare use between shift and non-shift workers. No differences were found in sickness absenteeism [Odds Ratio (OR) = 1.00 (95%‒Confidence Interval (CI): 0.61‒1.64)] and work performance [Regression coefficient (B) = -0.19 (95%‒CI: -0.65‒0.26)] due to ILI/ARI between shift and non-shift workers. In addition, healthcare use due to ILI/ARI was similar between shift and non-shift workers. Furthermore, similar general sickness absenteeism rates and work performance levels were found between shift and non-shift workers. As this is the first study that examined the associations with shift work due to ILI/ARI, further studies are needed to confirm our findings.

New insights into non-transcriptional regulation of mammalian core clock proteins

Mammalian circadian rhythms drive ∼24 h periodicity in a wide range of cellular processes, temporally coordinating physiology and behaviour within an organism, and synchronising this with the external day-night cycle. The canonical model for this timekeeping consists of a delayed negative-feedback loop, containing transcriptional activator complex CLOCK-BMAL1 (BMAL1 is also known as ARNTL) and repressors period 1, 2 and 3 (PER1, PER2 and PER3) and cryptochrome 1 and 2 (CRY1 and CRY2), along with a number of accessory factors. Although the broad strokes of this system are defined, the exact molecular mechanisms by which these proteins generate a self-sustained rhythm with such periodicity and fidelity remains a topic of much research. Recent studies have identified prominent roles for a number of crucial post-transcriptional, translational and, particularly, post-translational events within the mammalian circadian oscillator, providing an increasingly complex understanding of the activities and interactions of the core clock proteins. In this Review, we highlight such contemporary work on non-transcriptional events and set it within our current understanding of cellular circadian timekeeping.

The Association Between Shift Work and Immunological Biomarkers in Nurses

Objectives: Shift work is associated with several negative health effects. The underlying pathophysiological mechanisms are unclear, but low-grade inflammation has been suggested to play a role. This project aimed to determine whether levels of immunological biomarkers differ depending on work schedule, self-reported sleep duration, self-reported sleep quality, and presence of shift work disorder (study 1). Furthermore, we aimed to determine whether these biomarkers differ after a night of sleep vs. at the end of a night or a day shift (study 2).

Methods: In study 1, 390 nurses provided blood samples after a night of sleep with the dried blood spot method. In study 2, a subset of 55 nurses also provided blood samples after a day shift and after a night shift. The following biomarkers were measured: interleukin-1alpha, interleukin-1beta, interleukin-4, interleukin-6, interleukin-8, interleukin-10, interleukin-13, monocyte chemoattractant protein-1, interferon-gamma, and tumor necrosis factor-alpha. Multiple linear regressions with adjustment for age, sex and body mass index (study 1) and ANOVAs with repeated measures (study 2) were conducted.

Results: In study 1, neither work schedule, number of night shifts, number of quick returns (<11 h between consecutive shifts), sleep duration, poor sleep quality, nor shift work disorder were systematically associated with most of these biomarkers. Compared with day only work, day-evening work was associated with higher levels of IL-1alpha and IL-13, quick returns were associated with higher levels of IL-1beta and MCP-1, short sleep duration (<6 h) was associated with lower levels of IL-1beta and higher levels of TNF-alpha, and long sleep duration (8+ h) was associated with higher levels of IL-13. In study 2, IL-1beta levels were higher (large effect size) both after a day shift (14% increase) and a night shift (75% increase) compared with levels after a night of sleep. Similarly, TNF-alpha levels were higher (moderate-large effect size) after a day shift (50% increase) compared to after a night of sleep. In contrast, MCP-1 levels were lower (large effect size) both after a day shift (22% decrease) and a night shift (12% decrease) compared with after a night of sleep.

Conclusions: We found some indications that shift work influenced immunological biomarkers. The results should be interpreted with caution due to limitations, e.g., related to the sampling procedure and to low levels of biomarkers in the blood samples.

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.

Environmental Circadian Disruption Increases Stroke Severity and Dysregulates Immune Response

Understanding the health consequences of chronic disruption of circadian rhythms can contribute to improving prevention strategies for shift workers. Chronic circadian disruption in shift work has been linked to a higher risk of stroke. Dysregulated immune responses are also linked to circadian disruption and may be a factor in stroke outcomes in shift workers. In this study, we test the hypotheses that specific schedules of circadian disruption exacerbate inflammatory responses in the brain, causing an increase in infarct size after experimentally induced ischemic stroke. Mice were exposed to 1 of 5 different lighting schedules followed by a 30-min middle cerebral artery occlusion, then reperfusion and 3-day recovery. A history of weekly phase advances resulted in an increased infarct volume versus the control lighting schedule. These effects were shift-direction specific, nonpermanent, and required multiple shifts to occur. In a separate cohort, stereotaxic injections of lipopolysaccharide were given bilaterally after exposure to 1 of 3 different lighting schedules. Ratios of pro- to anti-inflammatory cytokine expression show dysregulated responses after a history of phase advances. We conclude that chronic circadian disruption leads to worsened stroke outcome in a direction- and schedule-specific manner likely because of priming of the inflammatory response in the brain. These pieces of evidence suggest that the health impacts of shift work may be improved by targeting shift work scheduling, inflammatory mediators, or both.

The Roles of Monocyte and Monocyte-Derived Macrophages in Common Brain Disorders

The brain is the most important and complex organ in most living creatures which serves as the center of the nervous system. The function of human brain includes controlling of the motion of the body and different organs and maintaining basic homeostasis. The disorders of the brain caused by a variety of reasons often severely impact the patients' normal life or lead to death in extreme cases. Monocyte is an important immune cell which is often recruited to the brain in a number of brain disorders. However, the role of monocytes may not be simply described as beneficial or detrimental. It significantly depends on the disease models and the stages of disease progression. In this review, we summarized the current knowledge about the role of monocytes and monocyte-derived macrophages during several common brain disorders. Major focuses include ischemic stroke, Alzheimer's disease, multiple sclerosis, intracerebral hemorrhage, and insomnia. The recruitment, differentiation, and function of monocyte in these diseases are reviewed.