Disruption of circadian rhythm by alternating light-dark cycles aggravates atherosclerosis development in APOE*3-Leiden.CETP mice

The circadian rhythm: A new target of natural products that can protect against diseases of the metabolic system, cardiovascular system, and nervous system

BACKGROUND

The treatment of metabolic system, cardiovascular system, and nervous system diseases remains to be explored. In the internal environment of organisms, the metabolism of substances such as carbohydrates, lipids and proteins (including biohormones and enzymes) exhibit a certain circadian rhythm to maintain the energy supply and material cycle needed for the normal activities of organisms. As a key factor for the health of organisms, the circadian rhythm can be disrupted by pathological conditions, and this disruption accelerates the progression of diseases and results in a vicious cycle. The current treatments targeting the circadian rhythm for the treatment of metabolic system, cardiovascular system, and nervous system diseases have certain limitations, and the identification of safer and more effective circadian rhythm regulators is needed.

AIM OF THE REVIEW

To systematically assess the possibility of using the biological clock as a natural product target for disease intervention, this work reviews a range of evidence on the potential effectiveness of natural products targeting the circadian rhythm to protect against diseases of the metabolic system, cardiovascular system, and nervous system. This manuscript focuses on how natural products restore normal function by affecting the amplitude of the expression of circadian factors, sleep/wake cycles and the structure of the gut microbiota.

KEY SCIENTIFIC CONCEPTS OF THE REVIEW

This work proposes that the circadian rhythm, which is regulated by the amplitude of the expression of circadian rhythm-related factors and the sleep/wake cycle, is crucial for diseases of the metabolic system, cardiovascular system and nervous system and is a new target for slowing the progression of diseases through the use of natural products. This manuscript provides a reference for the molecular modeling of natural products that target the circadian rhythm and provides a new perspective for the time-targeted action of drugs.

Chitosan revokes controlled-cortical impact generated neurological aberrations in circadian disrupted mice via TLR4-NLRP3 axis

The severity of inevitable neurological deficits and long-term psychiatric disorders in the aftermath of traumatic brain injury is influenced by pre-injury biological factors. Herein, we investigated the therapeutic effect of chitosan lactate on neurological and psychiatric aberrations inflicted by circadian disruption (CD) and controlled-cortical impact (CCI) injury in mice. Firstly, CD was developed in mice by altering sporadic day-night cycles for 2 weeks. Then, CCI surgery was performed using a stereotaxic ImpactOne device. Mice subjected to CCI displayed a significant disruption of motor coordination at 1-, 3- and 5-days post-injury (DPI) in the rotarod test. These animals showed anxiety- and depression-like behaviors in the elevated plus maze and forced-swim test at 14 and 15 DPI, respectively. Notably, mice subjected to CD + CCI exhibited severe cognitive impairment in Y-maze and novel object recognition tasks. The compromised neurological, psychiatric, and cognitive functions were mitigated in chitosan-treated mice (1 and 3 mg/mL). Immunohistochemistry and real-time PCR assay results revealed the magnified responses of prima facie biomarkers like glial-fibrillary acidic protein and ionized calcium-binding adaptor molecule 1 in the pericontusional brain region of the CD + CCI group, indicating aggravated inflammation. We also noted the depleted levels of brain-derived neurotrophic factor and augmented expression of toll-like receptor 4 (TLR4)-leucine-rich-containing family pyrin domain-containing 3 (NLRP3) signaling [apoptosis-associated-speck-like protein (ASC), caspase-1, and interleukin 1-β] in the pericontusional area of CD + CCI group. CCI-induced changes in the astrocyte-glia and aggravated immune responses were ameliorated in chitosan-treated mice. These results suggest that the neuroprotective effect of chitosan in CCI-induced brain injury may be mediated by inhibition of the TLR4-NLRP3 axis.

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.

Circadian disruption dysregulates lung gene expression associated with inflammatory lung injury

Rationale

Circadian systems drive the expression of multiple genes in nearly all cells and coordinate cellular-, tissue-, and system-level processes that are critical to innate immunity regulation.

Objective

We examined the effects of circadian rhythm disorganization, produced by light shift exposure, on innate immunity-mediated inflammatory lung responses including vascular permeability and gene expression in a C57BL/6J murine model of inflammatory lung injury.

Methods

A total of 32 C57BL/6J mice were assigned to circadian phase shifting (CPS) with intratracheal phosphate-buffered saline (PBS), CPS with intratracheal lipopolysaccharide (LPS), control (normal lighting) condition with intratracheal PBS, and control condition with intratracheal LPS. Bronchoalveolar lavage (BAL) protein, cell counts, tissue immunostaining, and differentially expressed genes (DEGs) were measured in lung tissues at 2 and 10 weeks.

Measurements and results

In mice exposed to both CPS and intratracheal LPS, both BAL protein and cell counts were increased at both 2 and 10 weeks compared to mice exposed to LPS alone. Multiple DEGs were identified in CPS-LPS-exposed lung tissues compared to LPS alone and were involved in transcriptional pathways associated with circadian rhythm disruption, regulation of lung permeability, inflammation with Rap1 signaling, and regulation of actin cytoskeleton. The most dysregulated pathways included myosin light chain kinase, MAP kinase, profilin 2, fibroblast growth factor receptor, integrin b4, and p21-activated kinase.

Conclusion

Circadian rhythm disruption results in exacerbated immune response and dysregulated expression of cytoskeletal genes involved in the regulation of epithelial and vascular barrier integrity-the mechanistic underpinnings of acute lung injury. Further studies need to explore circadian disorganization as a druggable target.

Circadian blood pressure dysregulation in children with obstructive sleep apnea

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) adversely affects normal blood pressure (BP) and may disrupt circadian BP patterns. We sought to examine 24-hour circadian BP rhythms in children with OSA and healthy controls.

METHODS

Children 5-14 years with OSA and healthy controls underwent 24-hour BP monitoring and actigraphy to quantify sleep. Shape invariant statistical models compared circadian BP patterns (e.g. times of BP peaks, time arrived at peak BP velocity [TAPV]) in the OSA and control groups.

RESULTS

The analytic sample included 219 children (mild OSA: n = 52; moderate-to-severe OSA (MS-OSA): n = 50; controls: n = 117). In the morning, the MS-OSA group had earlier TAPV for DBP than controls (51 minutes, p < 0.001). TAPV in the evening was earlier for the MS-OSA group than controls (SBP: 95 minutes, p < 0.001; DBP: 28 minutes, p = 0.028). At mid-day, SBP and DBP velocity nadirs were earlier for the MS-OSA group than controls (SBP: 57 minutes, p < 0.001; DBP: 38 minutes, p < 0.01). The MS-OSA group reached most BP values significantly earlier than controls; the largest differences were 118 minutes (SBP) and 43 minutes (DBP) (p < 0.001). SBP and DBP were elevated in the MS-OSA group (hours 18-21 and 7--12, respectively, p < 0.01) compared to controls. The MS-OSA group was prone to "non-dipping" compared to controls (SBP: odds ratio [OR] = 2.16, 95% CI: 1.09, 4.29; DBP: OR = 3.45, 95% CI: 1.21, 10.23).

CONCLUSIONS

Children with MS-OSA had changes in circadian BP patterns, namely earlier TAPV and BP peaks and nadirs than controls. Circadian disturbances in BP rhythms may be key to mapping the natural history of BP dysregulation in children with OSA.

Suppression of endoplasmic reticulum stress by 4-PBA enhanced atherosclerotic plaque stability via up-regulating CLOCK expression

Endoplasmic reticulum (ER) stress refers to a condition where the normal functioning of the ER is disrupted due to a variety of cellular stress factors. As a result, there is an accumulation of unfolded and misfolded proteins within the ER. Numerous studies have shown that ER stress can exacerbate inflammatory reactions and contribute to the development of various inflammatory diseases. However, the role of ER stress in the stability of atherosclerotic plaques remains poorly understood. In this study, we aimed to explore the potential impact of a specific ER stress inhibitor known as 4-phenyl butyric acid (4-PBA) on atherosclerosis in mice. The mice were fed a high-fat diet, and treatment with 4-PBA significantly improved the stability of the atherosclerotic plaques. This was evidenced by a reduction in oxidative stress and an increase in circadian locomotor output cycles kaput (CLOCK) protein and mRNA expression within the plaques. Additionally, 4-PBA reduced the expression of ER stress-related proteins and decreased apoptosis in the atherosclerotic plaques. In vitro investigation, we observed the effect of 4-PBA on vascular smooth muscle cells (VSMCs) that were exposed to oxidized low-density lipoprotein (ox-LDL), a significant contributor to the development of atherosclerosis. 4-PBA reduced reactive oxygen species (ROS) production and attenuated apoptosis, GRP78 and CHOP protein expression in ox-LDL-Induced VSMCs via up-regulating CLOCK expression. However, when the short hairpin RNA against CLOCK (sh-CLOCK) was introduced to the VSMCs, the protective effect of 4-PBA was abolished. This suggests that the up-regulation of CLOCK expression is crucial for the beneficial effects of 4-PBA on atherosclerotic plaque stability. This finding suggests that targeting ER stress and modulating CLOCK protein levels might be a promising way to enhance the stability of atherosclerotic plaques.

Nuclear receptor subfamily 1 group D member 1 suppresses the proliferation, migration of adventitial fibroblasts, and vascular intimal hyperplasia via mammalian target of rapamycin complex 1/β-catenin pathway

BACKGROUND

In-stent restenosis hardly limits the therapeutic effect of the percutaneous vascular intervention. Although the restenosis is significantly ameliorated after the application of new drug-eluting stents, the incidence of restenosis remains at a high level.

OBJECTIVE

Vascular adventitial fibroblasts (AFs) play an important role in intimal hyperplasia and subsequent restenosis. The current study was aimed to investigate the role of nuclear receptor subfamily 1, group D, member 1 (NR1D1) in the vascular intimal hyperplasia.

METHODS AND RESULTS

We observed increased expression of NR1D1 after the transduction of adenovirus carrying Nr1d1 gene (Ad-Nr1d1) in AFs. Ad-Nr1d1 transduction significantly reduced the numbers of total AFs, Ki-67-positive AFs, and the migration rate of AFs. NR1D1 overexpression decreased the expression level of β-catenin and attenuated the phosphorylation of the effectors of mammalian target of rapamycin complex 1 (mTORC1), including mammalian target of rapamycin (mTOR) and 4E binding protein 1 (4EBP1). Restoration of β-catenin by SKL2001 abolished the inhibitory effects of NR1D1 overexpression on the proliferation and migration of AFs. Surprisingly, the restoration of mTORC1 activity by insulin could also reverse the decreased expression of β-catenin, attenuated proliferation, and migration in AFs induced by NR1D1 overexpression. In vivo, we found that SR9009 (an agonist of NR1D1) ameliorated the intimal hyperplasia at days 28 after injury of carotid artery. We further observed that SR9009 attenuated the increased Ki-67-positive AFs, an essential part of vascular restenosis at days 7 after injury to the carotid artery.

CONCLUSION

These data suggest that NR1D1 inhibits intimal hyperplasia by suppressing the proliferation and migration of AFs in a mTORC1/β-catenin-dependent manner.

Light-induced circadian rhythm disorder leads to microvascular dysfunction via up-regulating NETs

Circadian rhythm is a physical, mental, and behavioral pattern over the course of 24-hour cycle, and its disturbance is associated with increased risk of cardiovascular diseases. Microvascular dysfunction serves as an important cause of cardiovascular disease, but the relationship between rhythm disturbances and microcirculation remains elusive. Herein, we constructed the mice model of circadian rhythm disturbance and investigated the alterations of microvascular conditions. It was revealed that coronary microcirculatory function and cardiac diastolic function were significantly reduced, along with endothelium-dependent diastolic function of microvessels remarkably impaired in the rhythm-disordered group of mice compared to the control group. Notably, rhythm disturbance led to a significant upregulation of neutrophil extracellular traps (NETs) levels in mice, which cause endothelial dysfunction by inhibiting microvascular endothelial cell activity and migration capacity as well as inducing apoptosis. Additionally, intraperitoneal injection of Cl-amidine suppressed the production of NETs, which further improved coronary microcirculatory function and endothelium-dependent diastolic function. In conclusion, this study demonstrated that circadian rhythm disorders could induce the development of coronary microvascular dysfunction (CMD) through the up-regulation of NETs, providing a potential therapeutic direction for the treatment of CMD.

Circadian Disruption in Night Shift Work and Its Association with Chronic Pulmonary Diseases

Globalization and the expansion of essential services over continuous 24 h cycles have necessitated the adaptation of the human workforce to shift-based schedules. Night shift work (NSW) causes a state of desynchrony between the internal circadian machinery and external environmental cues, which can impact inflammatory and metabolic pathways. The discovery of clock genes in the lung has shed light on potential mechanisms of circadian misalignment in chronic pulmonary disease. Here, the current knowledge of circadian clock disruption caused by NSW and its impact on lung inflammation and associated pathophysiology in chronic lung diseases, such as asthma, chronic obstructive pulmonary disease, pulmonary fibrosis, and COVID-19, is reviewed. Furthermore, the limitations of the current understanding of circadian disruption and potential future chronotherapeutic advances are discussed.

Sleep Variability, Eating Timing Variability, and Carotid Intima-Media Thickness in Early Adulthood

Background Day-to-day variability in sleep patterns and eating timing may disrupt circadian rhythms and has been linked with various adverse cardiometabolic outcomes. However, the extent to which variability in sleep patterns and eating timing relate to atherosclerotic development in subclinical stages remains unclear. Methods and Results Generally healthy adults (N=62, 29.3±7.3 years, 66% female) completed 14 days of sleep and dietary assessments via wrist accelerometry and photo-assisted diet records, respectively. Variability in sleep duration, sleep onset, eating onset (time of first caloric consumption), eating offset (time of last caloric consumption), and caloric midpoint (time at which 50% of total daily calories are consumed) were operationalized as the SD across 14 days for each variable. Separate regression models evaluated the cross-sectional associations between sleep and eating variability metrics with end-diastolic carotid intima-media thickness (CIMT) measured via ultrasonography. Models adjusted for age, sex, systolic blood pressure, sleep duration, and total energy intake. Each 60-minute increase in sleep duration SD and sleep onset SD were associated with a 0.049±0.016 mm (P=0.003) and 0.048±0.017 mm (P=0.007) greater CIMT, respectively. Variability in eating onset and offset were not associated with CIMT; however, each 60-minute increase in caloric midpoint SD was associated with a 0.033±0.015 mm greater CIMT (P=0.029). Exploratory post hoc analyses suggested that sleep duration SD and sleep onset SD were stronger correlates of CIMT than caloric midpoint SD. Conclusions Variability in sleep patterns and eating timing are positively associated with clinically relevant increases in CIMT, a biomarker of subclinical atherosclerosis, in early adulthood.

Reversible suppression of circadian-driven locomotor rhythms in mice using a gradual fragmentation of the day-night cycle

Circadian rhythms are regulated by molecular clockwork and drive 24-h behaviors such as locomotor activity, which can be rendered non-functional through genetic knockouts of clock genes. Circadian rhythms are robust in constant darkness (DD) but are modulated to become exactly 24 h by the external day-night cycle. Whether ill-timed light and dark exposure can render circadian behaviors non-functional to the extent of genetic knockouts is less clear. In this study, we discovered an environmental approach that led to a reduction or lack in rhythmic 24-h-circadian wheel-running locomotor behavior in mice (referred to as arrhythmicity). We first observed behavioral circadian arrhythmicity when mice were gradually exposed to a previously published disruptive environment called the fragmented day-night cycle (FDN-G), while maintaining activity alignment with the four dispersed fragments of darkness. Remarkably, upon exposure to constant darkness (DD) or constant light (LL), FDN-G mice lost any resemblance to the FDN-G-only phenotype and instead, exhibited sporadic activity bursts. Circadian rhythms are maintained in control mice with sudden FDN exposure (FDN-S) and fully restored in FDN-G mice either spontaneously in DD or after 12 h:12 h light-dark exposure. This is the first study to generate a light-dark environment that induces reversible suppression of circadian locomotor rhythms in mice.

Circadian rhythm in cardiovascular diseases: a bibliometric analysis of the past, present, and future

BACKGROUND

One of the most prominent features of living organisms is their circadian rhythm, which governs a wide range of physiological processes and plays a critical role in maintaining optimal health and function in response to daily environmental changes. This work applied bibliometric analysis to explore quantitative and qualitative trends in circadian rhythm in cardiovascular diseases (CVD). It also aims to identify research hotspots and provide fresh suggestions for future research.

METHODS

The Web of Science Core Collection was used to search the data on circadian rhythm in CVD. HistCite, CiteSpace, and VOSviewer were used for bibliometric analysis and visualization. The analysis included the overall distribution of yearly outputs, top nations, active institutions and authors, core journals, co-cited references, and keywords. To assess the quality and efficacy of publications, the total global citation score (TGCS) and total local citation score (TLCS) were calculated.

RESULTS

There were 2102 papers found to be associated with the circadian rhythm in CVD, with the overall number of publications increasing year after year. The United States had the most research citations and was the most prolific country. Hermida RC, Young ME, and Ayala DE were the top three writers. The three most notable journals on the subject were Chronobiology International, Hypertension Research, and Hypertension. In the early years, the major emphasis of circadian rhythm in CVD was hormones. Inflammation, atherosclerosis, and myocardial infarction were the top developing research hotspots.

CONCLUSION

Circadian rhythm in CVD has recently received a lot of interest from the medical field. These topics, namely inflammation, atherosclerosis, and myocardial infarction, are critical areas of investigation for understanding the role of circadian rhythm in CVD. Although they may not be future research priorities, they remain of significant importance. In addition, how to implement these chronotherapy theories in clinical practice will depend on additional clinical trials to get sufficient trustworthy clinical evidence.

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.

Chronic environmental circadian disruption increases atherosclerosis and dyslipidemia in female, but not male, ApolipoproteinE-deficient mice

Shift work chronically disrupts circadian rhythms and increases the risk of developing cardiovascular disease. However, the mechanisms linking shift work and cardiovascular disease are largely unknown. The goal of this study was to investigate the effects of chronically shifting the light-dark (LD) cycle, which models the disordered exposure to light that may occur during shift work, on atherosclerosis. Atherosclerosis is the progressive accumulation of lipid-filled lesions within the artery wall and is the leading cause of cardiovascular disease. We studied ApolipoproteinE-deficient (ApoE -/- ) mice that are a well-established model of atherosclerosis. Male and female ApoE -/- mice were housed in control 12L:12D or chronic LD shift conditions for 12 weeks and fed low-fat diet. In the chronic LD shift condition, the light-dark cycle was advanced by 6 h every week. We found that chronic LD shifts exacerbated atherosclerosis in female, but not male, ApoE -/- mice. In females, chronic LD shifts increased total serum cholesterol concentrations with increased atherogenic VLDL/LDL particles. Chronic LD shifts did not affect food intake, activity, or body weight in male or female ApoE -/- mice. We also examined eating behavior in female ApoE -/- mice since aberrant meal timing has been linked to atherosclerosis. The phases of eating behavior rhythms, like locomotor activity rhythms, gradually shifted to the new LD cycle each week in the chronic LD shift group, but there was no effect of the LD shift on the amplitudes of the eating rhythms. Moreover, the duration of fasting intervals was not different in control 12L:12D compared to chronic LD shift conditions. Together these data demonstrate that female ApoE -/- mice have increased atherosclerosis when exposed to chronic LD shifts due to increased VLDL/LDL cholesterol, independent of changes in energy balance or feeding-fasting cycles.

Circadian gene CLOCK accelerates atherosclerosis by promoting endothelial autophagy

Atherosclerosis (AS) is a chronic inflammatory disease which gives rise to life-threatening complications like ischemic stroke. Rupture of carotid atherosclerotic plaque is the main cause of ischemic stroke. Emerging evidence has demonstrated that disturbed circadian rhythms could accelerate the progression of atherosclerosis by regulating endothelial function. Moreover, our previous study implicated the circadian gene circadian locomotor output cycles kaput (CLOCK) in the pathogenesis of unstable plaques. In this study, we explored the underlying mechanism that CLOCK mediates endothelial cell autophagy involved in the progression of AS. Circadian and autophagy gene expression was analyzed in the GSE41571 dataset and human carotid atherosclerotic plaque samples. Then we used ox-LDL to treat HUVECs, and analyzed CLOCK and autophagy gene in endothelial cells. Besides that, we comprehensively analyzed in vivo experiments to explore the function of CLOCK in autophagy and atherosclerosis using different staining including HE, MT and IF staining. In the dataset and patient samples, CLOCK expression and autophagy were decreased in the unstable plaque group compared with the stable group. Decreased Beclin1, ATG5, LC3, and CLOCK were also observed in HUVECs under oxidative stress condition which also enhances cell proliferation. In vivo, we also found decreasing level of CLOCK, Beclin1, LC3 and ATG5 in ApoE^-/- mice compared with WT mice. Silencing of CLOCK in ApoE^-/- mice may further aggravate atherosclerosis including decreased cap thickness and collagens. Our findings implicated that downregulation CLOCK would impair endothelial cell autophagy and accelerate atherosclerotic plaque, which provides a novel strategy for treatment of progression in AS.

Circadian rhythm disruption exacerbates the progression of macrophage dysfunction and alveolar bone loss in periodontitis

Macrophages are highly implicated in the progression of periodontitis, while circadian rhythm disruption (CRD) promotes the inflammatory response of macrophages in many diseases. However, the effects of CRD on periodontitis and the role of macrophages in this process remain unclear. Histone lysinedemethylase6a (Kdm6a), a histone demethylase, has recently been identified as a key regulator of macrophage-induced inflammation. Here, we established an experimental periodontitis model by injecting lipopolysaccharide (LPS) derived from Porphyromonas gingivalis with or without periodontal ligation in mice exposed to an 8-h time shift jet-lag schedule every 3 days. By histomorphometry, tartrate acid phosphatase (TRAP) staining, RT-qPCR, ELISA, immunohistochemistry and immunofluorescence analysis, we found that CRD promoted the inflammatory response, alveolar bone resorption, macrophage infiltration and Kdm6a expression in macrophages. Macrophage-specific Kdm6a knockout mice were further used to elucidate the effects of Kdm6a deficiency on periodontitis. Kdm6a deletion in macrophages rescued periodontal tissue inflammation, osteoclastogenesis, and alveolar bone loss in a mouse model of periodontitis. These findings suggest that CRD may intensify periodontitis by increasing the infiltration and activation of macrophages. Kdm6a promotes the inflammatory response in macrophages, which may participate in aggravated periodontitis via CRD.

Mechanical injury accentuates lipid deposition in ApoE-/- mice and advance aortic valve stenosis: A novel modified aortic valve stenosis model

Background

Current mouse models still have limitations in studying aortic valve stenosis (AVS). A suitable animal model bearing a close resemblance to the pathophysiological processes of humans needs to be developed. Here, we combined two risk factors to create a mouse model that mimics the pathological features of human AVS.

Methods and results

We combined WI and hyperlipidemia in ApoE^-/- mice to explore the synergistic effect on the stenosis of the aortic valve. Transthoracic echocardiography revealed progressively increased peak velocity with age in ApoE^-/- mice to velocities above C57 mice when fed a high-fat diet after wire injury. Moreover, ApoE^-/- mice demonstrated lower cusp separation and lower aortic valve area after 8 weeks vs. C57 mice. Gross morphology and MRI showed advanced thickening, sclerosis aortic valve, narrowing of the orifice area, and micro-CT showed obvious calcification in the aortic valves in the hyperlipidemia group after wire injury. Histopathology studies showed thickening and fibrosis of aortic valve leaflets in the hyperlipidemia group after wire injury. Notably, lipid deposition was observed in ApoE^-/- mice 8 weeks after wire injury, accompanied by overexpressed apoB and apoA proteins. After wire injury, the hyperlipidemia group exhibited augmented inflammation, ROS production, and apoptosis in the leaflets. Moreover, the combination group exhibited advanced fibro-calcific aortic valves after wire injury.

Conclusion

Overall, we present the synergistic effect of wire injury and hyperlipidemia on lipoproteins deposition in the development of AVS in ApoE^-/- mice, this model bear close resemblance to human AVS pathology.

Screening for key genes in circadian regulation in advanced atherosclerosis: A bioinformatic analysis

Background

Atherosclerosis (AS) is the most important cardiovascular disease threatening human health, leading to adverse events such as myocardial infarction and stroke. The research on the pathogenesis and causes of AS is being improved step by step, and many factors are associated with AS. However, the relationship between circadian regulation and the pathogenesis of AS is still unclear. Our study identified 2 key genes of circadian regulation in AS by bioinformatics analysis, which provides new perspectives to understand the relationship between circadian rhythm and AS.

Methods

We downloaded samples of early and advanced AS from public databases, screened key genes by weighted gene co-expression network analysis (WGCNA) and Lasso, calculated the immune cell content of the samples using "CIBERSORT," and analyzed the relationship between key genes and immune cells.

Results

We obtained the most relevant core modules for advanced AS and analyzed the functions of these modules. Two circadian rhythm-related genes were obtained, which influence the immune infiltration of this late AS. ROC curves demonstrated the efficacy of key genes to differentiate between early and advanced AS.

Conclusion

We identified 2 genes most associated with circadian rhythms in advanced AS, whose association with AS has not been elucidated and may become the next therapeutic target.

Circadian rhythms of risk factors and management in atherosclerotic and hypertensive vascular disease: Modern chronobiological perspectives of an ancient disease

Atherosclerosis, a chronic inflammatory disease of the arteries that appears to have been as prevalent in ancient as in modern civilizations, is predisposing to life-threatening and life-ending cardiac and vascular complications, such as myocardial and cerebral infarctions. The pathogenesis of atherosclerosis involves intima plaque buildup caused by vascular endothelial dysfunction, cholesterol deposition, smooth muscle proliferation, inflammatory cell infiltration and connective tissue accumulation. Hypertension is an independent and controllable risk factor for atherosclerotic cardiovascular disease (CVD). Conversely, atherosclerosis hardens the arterial wall and raises arterial blood pressure. Many CVD patients experience both atherosclerosis and hypertension and are prescribed medications to concurrently mitigate the two disease conditions. A substantial number of publications document that many pathophysiological changes caused by atherosclerosis and hypertension occur in a manner dependent upon circadian clocks or clock gene products. This article reviews progress in the research of circadian regulation of vascular cell function, inflammation, hemostasis and atherothrombosis. In particular, it delineates the relationship of circadian organization with signal transduction and activation of the renin-angiotensin-aldosterone system as well as disturbance of the sleep/wake circadian rhythm, as exemplified by shift work, metabolic syndromes and obstructive sleep apnea (OSA), as promoters and mechanisms of atherogenesis and risk for non-fatal and fatal CVD outcomes. This article additionally updates advances in the clinical management of key biological processes of atherosclerosis to optimally achieve suppression of atherogenesis through chronotherapeutic control of atherogenic/hypertensive pathological sequelae.

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.

Effects of sleep deprivation on coronary heart disease

The presence of artificial light enables humans to be active 24 h a day. Many people across the globe live in a social culture that encourages staying up late to meet the demands of various activities, such as work and school. Sleep deprivation (SD) is a severe health problem in modern society. Meanwhile, as with cardiometabolic disease, there was an obvious tendency that coronary heart disease (CHD) to become a global epidemic chronic disease. Specifically, SD can significantly increase the morbidity and mortality of CHD. However, the underlying mechanisms responsible for the effects of SD on CHD are multilayered and complex. Inflammatory response, lipid metabolism, oxidative stress, and endothelial function all contribute to cardiovascular lesions. In this review, the effects of SD on CHD development are summarized, and SD-related pathogenesis of coronary artery lesions is discussed. In general, early assessment of SD played a vital role in preventing the harmful consequences of CHD.

Récepteurs nucléaires et rythmes circadiens

L’horloge circadienne programme l’ensemble des processus physiologiques, dont l’activité du système immunitaire, à des moments précis de la journée. Elle permet d’optimiser les fonctions de l’organisme en anticipant les changements quotidiens tels que les cycles jour/nuit. Nos habitudes de vie comme l’exposition à la lumière artificielle ou une prise alimentaire irrégulière désynchronisent cependant cette horloge et provoquent des maladies, par exemple inflammatoires. Au niveau moléculaire, elle consiste en un réseau de facteurs de transcription dont certains sont des récepteurs nucléaires, activables par des ligands. Une meilleure compréhension des rythmes biologiques et du rôle des récepteurs nucléaires de l’horloge circadienne permettrait d’ouvrir un champ thérapeutique nouveau. La chronothérapie qui consiste en l’administration d’un composé pharmacologique au moment de la journée le plus propice, permettrait, en ciblant ces récepteurs, d’optimiser l’efficacité du traitement et d’en réduire les possibles effets secondaires.

Digital circadian and sleep health in individual hospital shift workers: A cross sectional telemonitoring study

BACKGROUND

Telemonitoring of circadian and sleep cycles could identify shift workers at increased risk of poor health, including cancer and cardiovascular diseases, thus supporting personalized prevention.

METHODS

The Circadiem cross-sectional study aimed at determining early warning signals of risk of health alteration in hospital nightshifters (NS) versus dayshifters (DS, alternating morning and afternoon shifts). Circadian rhythmicity in activity, sleep, and temperature was telemonitored on work and free days for one week. Participants wore a bluetooth low energy thoracic accelerometry and temperature sensor that was wirelessly connected to a GPRS gateway and a health data hub server. Hidden Markov modelling of activity quantified Rhythm Index, rest quality (probability, p1-1, of remaining at rest), and rest duration. Spectral analyses determined periods in body surface temperature and accelerometry. Parameters were compared and predictors of circadian and sleep disruption were identified by multivariate analyses using information criteria-based model selection. Clusters of individual shift work response profiles were recognized.

FINDINGS

Of 140 per-protocol participants (133 females), there were 63 NS and 77 DS. Both groups had similar median rest amount, yet NS had significantly worse median rest-activity Rhythm Index (0·38 [IQR, 0·29-0·47] vs. 0·69 [0·60-0·77], p<0·0001) and rest quality p1-1 (0·94 [0·94-0·95] vs 0·96 [0·94-0·97], p<0·0001) over the whole study week. Only 48% of the NS displayed a circadian period in temperature, as compared to 70% of the DS (p=0·026). Poor p1-1 was associated with nightshift work on both work (p<0·0001) and free days (p=0·0098). The number of years of past night work exposure predicted poor rest-activity Rhythm Index jointly with shift type, age and chronotype on workdays (p= 0·0074), and singly on free days (p=0·0005).

INTERPRETATION

A dedicated analysis toolbox of streamed data from a wearable device identified circadian and sleep rhythm markers, that constitute surrogate candidate endpoints of poor health risk in shift-workers.

FUNDING

French Agency for Food, Environmental and Occupational Health & Safety (EST-2014/1/064), University of Warwick, Medical Research Council (United Kingdom, MR/M013170), Cancer Research UK(C53561/A19933).

Building a model for predicting metabolic syndrome using artificial intelligence based on an investigation of whole-genome sequencing

Background

The circadian system is responsible for regulating various physiological activities and behaviors and has been gaining recognition. The circadian rhythm is adjusted in a 24-h cycle and has transcriptional–translational feedback loops. When the circadian rhythm is interrupted, affecting the expression of circadian genes, the phenotypes of diseases could amplify. For example, the importance of maintaining the internal temporal homeostasis conferred by the circadian system is revealed as mutations in genes coding for core components of the clock result in diseases. This study will investigate the association between circadian genes and metabolic syndromes in a Taiwanese population.

Methods

We performed analysis using whole-genome sequencing, read vcf files and set target circadian genes to determine if there were variants on target genes. In this study, we have investigated genetic contribution of circadian-related diseases using population-based next generation whole genome sequencing. We also used significant SNPs to create a metabolic syndrome prediction model. Logistic regression, random forest, adaboost, and neural network were used to predict metabolic syndrome. In addition, we used random forest model variables importance matrix to select 40 more significant SNPs, which were subsequently incorporated to create new prediction models and to compare with previous models. The data was then utilized for training set and testing set using five-fold cross validation. Each model was evaluated with the following criteria: area under the receiver operating characteristics curve (AUC), precision, F1 score, and average precision (the area under the precision recall curve).

Results

After searching significant variants, we used Chi-Square tests to find some variants. We found 186 significant SNPs, and four predicting models which used 186 SNPs (logistic regression, random forest, adaboost and neural network), AUC were 0.68, 0.8, 0.82, 0.81 respectively. The F1 scores were 0.412, 0.078, 0.295, 0.552, respectively. The other three models which used the 40 SNPs (logistic regression, adaboost and neural network), AUC were 0.82, 0.81, 0.81 respectively. The F1 scores were 0.584, 0.395, 0.574, respectively.

Conclusions

Circadian gene defect may also contribute to metabolic syndrome. Our study found several related genes and building a simple model to predict metabolic syndrome.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03379-7.

Macrophage CD36 and TLR4 Cooperation Promotes Foam Cell Formation and VSMC Migration and Proliferation Under Circadian Oscillations

Circadian rhythm disorders can accelerate atherosclerosis. This study aimed to determine the role of circadian disordered macrophages in atherosclerotic development. Mice were divided into NC group (normal circadian rhythm), L24 group (constant light), D12L12 group (weekly shift light/dark cycle), and D24 group (constant dark). Atherosclerotic progression was significantly accelerated in L24, D12L12, and D24 groups. Peritoneal macrophages from circadian disruption groups exhibited enhanced cytokine secretion and foam cell formation. Migration and proliferation of vascular smooth muscle cells (VSMCs) were increased under the conditioned medium of circadian disordered macrophages. The blockade of CD36 markedly inhibited foam cell formation. Compared with blocking CD36 or TLR4 alone, the co-inhibition of CD36 and TLR4 in macrophages further reduced cytokine secretion and more effectively inhibited VSMC migration and proliferation. In conclusion, the activation of CD36 and TLR4 in circadian disordered macrophages promotes foam cell formation and cytokine secretion and enhances VSMC migration and proliferation. Circadian rhythm disorders promote lipid uptake and cytokine secretion of macrophages by regulating CD36 and TLR4, and enhance VSMC migration and proliferation through the paracrine effect of macrophages.

Chronic Circadian Rhythm Disturbance Accelerates Knee Cartilage Degeneration in Rats Accompanied by the Activation of the Canonical Wnt/β-Catenin Signaling Pathway

With the gradual deepening of understanding of systemic health and quality of life, the factors affecting osteoarthritis (OA) are not limited to mechanical injury, metabolic abnormality, age and obesity, etc., but circadian rhythm, which plays a non-negligible role in human daily life. The purpose of this study was to explore the molecular mechanism of chronic circadian rhythm disturbance (CRD) inducing cartilage OA-like degeneration. Rats with the anterior cruciate ligament excision transection (ACLT) were used to establish the early-stage OA model (6-week). The light/dark (LD) cycle shifted 12 h per week for 22 weeks in order to establish a chronic CRD model. BMAL1 knockdown (KD) and Wnt/β-catenin pathway inhibition were performed in chondrocytes. The contents of proinflammatory factors and OA biomarkers in serum and chondrocyte secretions were detected by ELISA. Pathological and immunohistochemical staining of articular cartilage indicated the deterioration of cartilage. WB and qPCR were used to evaluate the relationship between matrix degradation and the activation of Wnt/β-catenin signaling pathway in chondrocytes. We found that chronic CRD could cause OA-like pathological changes in knee cartilage of rats, accelerating cartilage matrix degradation and synovial inflammation. The expression of MMP-3, MMP-13, ADAMTS-4, and β-catenin increased significantly; BMAL1, Aggrecan, and COL2A1 decreased significantly in either LD-shifted cartilage or BMAL1-KD chondrocytes. The expression of β-catenin and p-GSK-3β elevated, while p-β-catenin and GSK-3β diminished. The inhibitor XAV-939 was able to mitigated the increased inflammation produced by transfected siBMAL1. Our study demonstrates that chronic CRD disrupts the balance of matrix synthesis and catabolic metabolism in cartilage and chondrocytes, and it is related to the activation of the canonical Wnt/β-catenin signaling pathway.

Research methods for animal models of atherosclerosis (Review)

Atherosclerosis is a chronic inflammatory disease that threatens human health and lives by causing vascular stenosis and plaque rupture. Various animal models have been employed for elucidating the pathogenesis, drug development and treatment validation studies for atherosclerosis. To the best of our knowledge, the species used for atherosclerosis research include mice, rats, hamsters, rabbits, pigs, dogs, non-human primates and birds, among which the most commonly used ones are mice and rabbits. Notably, apolipoprotein E knockout (KO) or low-density lipoprotein receptor KO mice have been the most widely used animal models for atherosclerosis research since the late 20th century. Although the aforementioned animal models can form atherosclerotic lesions, they cannot completely simulate those in humans with respect to lesion location, lesion composition, lipoprotein composition and physiological structure. Hence, an appropriate animal model needs to be selected according to the research purpose. Additionally, it is necessary for atherosclerosis research to include quantitative analysis results of atherosclerotic lesion size and plaque composition. Laboratory animals can provide not only experimental tissues for in vivo studies but also cells needed for in vitro experiments. The present review first summarizes the common animal models and their practical applications, followed by focus on mouse and rabbit models and elucidating the methods to quantify atherosclerotic lesions. Finally, the methods of culturing endothelial cells, macrophages and smooth muscle cells were elucidated in detail and the experiments involved in atherosclerosis research were discussed.

Circadian Clock-Controlled Checkpoints in the Pathogenesis of Complex Disease

The circadian clock coordinates physiology, metabolism, and behavior with the 24-h cycles of environmental light. Fundamental mechanisms of how the circadian clock regulates organ physiology and metabolism have been elucidated at a rapid speed in the past two decades. Here we review circadian networks in more than six organ systems associated with complex disease, which cluster around metabolic disorders, and seek to propose critical regulatory molecules controlled by the circadian clock (named clock-controlled checkpoints) in the pathogenesis of complex disease. These include clock-controlled checkpoints such as circadian nuclear receptors in liver and muscle tissues, chemokines and adhesion molecules in the vasculature. Although the progress is encouraging, many gaps in the mechanisms remain unaddressed. Future studies should focus on devising time-dependent strategies for drug delivery and engagement in well-characterized organs such as the liver, and elucidating fundamental circadian biology in so far less characterized organ systems, including the heart, blood, peripheral neurons, and reproductive systems.

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.

Review: Circadian clocks and rhythms in the vascular tree

The progression of vascular disease is influenced by many factors including aging, gender, diet, hypertension, and poor sleep. The intrinsic vascular circadian clock and the timing it imparts on the vasculature both conditions and is conditioned by all these variables. Circadian rhythms and their molecular components are rhythmically cycling in each endothelial cell, smooth muscle cell, in each artery, arteriole, vein, venule, and capillary. New research continues to tackle how circadian clocks act in the vasculature, describing influences in experimental and human disease, identifying potential target genes, compensatory molecules, that ultimately reveal a complexity that is vascular-bed-specific, cell-type-specific, and even single-cell-specific. Though we are yet to achieve a complete understanding, here we survey recent observations that are shedding more light on the nature of the interaction between circadian rhythms and the vascular system with implications for blood vessel disease.

A multi-level assessment of the bidirectional relationship between aging and the circadian clock

The daily temporal order of physiological processes and behavior contribute to the wellbeing of many organisms including humans. The central circadian clock, which coordinates the timing within our body, is located in the suprachiasmatic nucleus (SCN) of the hypothalamus. Like in other parts of the brain, aging impairs the SCN function, which in turn promotes the development and progression of aging-related diseases. We here review the impact of aging on the different levels of the circadian clock machinery-from molecules to organs-with a focus on the role of the SCN. We find that the molecular clock is less effected by aging compared to other cellular components of the clock. Proper rhythmic regulation of intracellular signaling, ion channels and neuronal excitability of SCN neurons are greatly disturbed in aging. This suggests a disconnection between the molecular clock and the electrophysiology of these cells. The neuronal network of the SCN is able to compensate for some of these cellular deficits. However, it still results in a clear reduction in the amplitude of the SCN electrical rhythm, suggesting a weakening of the output timing signal. Consequently, other brain areas and organs not only show aging-related deficits in their own local clocks, but also receive a weaker systemic timing signal. The negative spiral completes with the weakening of positive feedback from the periphery to the SCN. Consequently, chronotherapeutic interventions should aim at strengthening overall synchrony in the circadian system using life-style and/or pharmacological approaches.

The inhibitory effect of melatonin on human prostate cancer

Prostate cancer (PCa) is one of the most commonly diagnosed human cancers in males. Nearly 191,930 new cases and 33,330 new deaths of PCa are estimated in 2020. Androgen and androgen receptor pathways played essential roles in the pathogenesis of PCa. Androgen depletion therapy is the most used therapies for primary PCa patients. However, due to the high relapse and mortality of PCa, developing novel noninvasive therapies have become the focus of research. Melatonin is an indole-like neurohormone mainly produced in the human pineal gland with a prominent anti-oxidant property. The anti-tumor ability of melatonin has been substantially confirmed and several related articles have also reported the inhibitory effect of melatonin on PCa, while reviews of this inhibitory effect of melatonin on PCa in recent 10 years are absent. Therefore, we systematically discuss the relationship between melatonin disruption and the risk of PCa, the mechanism of how melatonin inhibited PCa, and the synergistic benefits of melatonin and other drugs to summarize current understandings about the function of melatonin in suppressing human prostate cancer. We also raise several unsolved issues that need to be resolved to translate currently non-clinical trials of melatonin for clinic use. We hope this literature review could provide a solid theoretical basis for the future utilization of melatonin in preventing, diagnosing and treating human prostate cancer.

Circadian Rhythm: Potential Therapeutic Target for Atherosclerosis and Thrombosis

Every organism has an intrinsic biological rhythm that orchestrates biological processes in adjusting to daily environmental changes. Circadian rhythms are maintained by networks of molecular clocks throughout the core and peripheral tissues, including immune cells, blood vessels, and perivascular adipose tissues. Recent findings have suggested strong correlations between the circadian clock and cardiovascular diseases. Desynchronization between the circadian rhythm and body metabolism contributes to the development of cardiovascular diseases including arteriosclerosis and thrombosis. Circadian rhythms are involved in controlling inflammatory processes and metabolisms, which can influence the pathology of arteriosclerosis and thrombosis. Circadian clock genes are critical in maintaining the robust relationship between diurnal variation and the cardiovascular system. The circadian machinery in the vascular system may be a novel therapeutic target for the prevention and treatment of cardiovascular diseases. The research on circadian rhythms in cardiovascular diseases is still progressing. In this review, we briefly summarize recent studies on circadian rhythms and cardiovascular homeostasis, focusing on the circadian control of inflammatory processes and metabolisms. Based on the recent findings, we discuss the potential target molecules for future therapeutic strategies against cardiovascular diseases by targeting the circadian clock.

Light-Dark Patterns Mirroring Shift Work Accelerate Atherosclerosis and Promote Vulnerable Lesion Phenotypes

Background

Despite compelling epidemiological evidence that circadian disruption inherent to long‐term shift work enhances atherosclerosis progression and vascular events, the underlying mechanisms remain poorly understood. A challenge to the use of mouse models for mechanistic and interventional studies involving light‐dark patterns is that the spectral and absolute sensitivities of the murine and human circadian systems are very different, and light stimuli in nocturnal mice should be scaled to represent the sensitivities of the human circadian system.

Methods and Results

We used calibrated devices to deliver to low‐density lipoprotein receptor knockout mice light‐dark patterns representative of that experienced by humans working day shifts or rotating shift schedules. Mice under day shifts were maintained under regular 12 hours of light and 12 hours of dark cycles. Mice under rotating shift schedules were subjected for 11 weeks to reversed light‐dark patterns 4 days in a row per week, followed by 3 days of regular light‐dark patterns. In both protocols the light phases consisted of monochromatic green light at an irradiance of 4 µW/cm². We found that the shift work paradigm disrupts the foam cell's molecular clock and increases endoplasmic reticulum stress and apoptosis. Lesions of mice under rotating shift schedules were larger and contained less prostabilizing fibrillar collagen and significantly increased areas of necrosis.

Conclusions

Low‐density lipoprotein receptor knockout mice under light‐dark patterns analogous to that experienced by rotating shift workers develop larger and more vulnerable plaques and may represent a valuable model for further mechanistic and/or interventional studies against the deleterious vascular effects of rotating shift work.

Time for Novel Strategies to Mitigate Cardiometabolic Risk in Shift Workers

Circadian disruption induced by shift work is robustly associated with obesity, diabetes, and cardiovascular disease in humans. Less well-known are the mechanisms underlying these associations, and the effectiveness of strategies to reduce cardiometabolic risk in the shift work population. In this review, the different ways in which shift work can deteriorate cardiometabolic health, and how to use this information to reflect on various risk-mitigating strategies, is discussed. While individual strategies appear promising in animal studies, the multifactorial disease risk in shift workers likely requires a multidisciplinary approach. Therefore, the need for individually-tailored combined lifestyle interventions, that could be essential in reducing cardiometabolic disorders in the large population of shift workers in our 24/7 society, is argued.

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.

Circadian rhythm and atherosclerosis (Review)

Atherosclerosis is the leading cause of morbidity and mortality worldwide. The underlying pathogenesis involves multiple metabolic disorders, endothelial dysfunction and a maladaptive immune response, and leads to chronic arterial wall inflammation. Numerous normal physiological activities exhibit daily rhythmicity, including energy metabolism, vascular function and inflammatory immunoreactions, and disrupted or misaligned circadian rhythms may promote the progression of atherosclerosis. However, the association between the circadian rhythm and atherosclerosis remains to be fully elucidated. In the present review, the effects of the circadian rhythm on atherosclerosis progression are discussed.

Continuous Light Does Not Affect Atherosclerosis in APOE*3-Leiden.CETP Mice

Artificial light exposure is associated with dyslipidemia in humans, which is a major risk factor for the development of atherosclerotic cardiovascular disease. However, it remains unclear whether artificial light at night can exacerbate atherosclerosis. In this study, we exposed female APOE*3-Leiden.CETP mice, a well-established model for human-like lipid metabolism and atherosclerosis, to either a regular light-dark cycle or to constant bright light for 14 weeks. Mice exposed to constant light demonstrated a minor reduction in food intake, without any effect on body weight, body composition, or the weight of metabolic organs. Constant light increased the plasma levels of proatherogenic non–high-density lipoprotein (HDL) cholesterol but did not increase the size or severity of atherosclerotic lesions in the aortic root. Mice exposed to constant light did show lower immune cell counts, which could explain the absence of an effect of atherosclerosis despite increased non–HDL cholesterol levels. Behavioral analysis demonstrated variability in the response of mice to the light intervention. Constant light completely blunted behavioral rhythms in some mice, while others extended their behavioral period. However, rhythm strength was not an important determinant of atherosclerosis. Altogether, these results demonstrate that constant bright light does not affect atherosclerosis in APOE*3-Leiden.CETP mice. Whether artificial light exposure contributes to cardiovascular disease risk in humans remains to be investigated.

Circadian Control of Inflammasome Pathways: Implications for Circadian Medicine

The innate immune system senses “non-self” molecules derived from pathogens (PAMPs) as well as endogenous damage-associated molecular patterns (DAMPs) and promotes sterile inflammation that is necessary for injury resolution, tissue repair/regeneration, and homeostasis. The NOD-, LRR- and pyrin domain containing protein 3 (NLRP3) is an innate immune signaling complex whose assembly and activation can be triggered by various signals ranging from microbial molecules to ATP or the abnormal accumulation of crystals, thus leading to IL-1β and IL-18 maturation and secretion. Deregulation of the NLRP3 signaling cascade is associated with numerous inflammatory and metabolic diseases including rheumatoid arthritis, gout, atherosclerosis or type 2 diabetes. Interestingly, the circadian clock controls numerous inflammatory processes while clock disruption leads to or exacerbates inflammation. Recently, the biological clock was demonstrated to control NLRP3 expression and activation, thereby controlling IL-1β and IL-18 secretion in diverse tissues and immune cells, particularly macrophages. Circadian oscillations of NLRP3 signaling is lost in models of clock disruption, contributing to the development of peritonitis, hepatitis, or colitis. Sterile inflammation is also an important driver of atherosclerosis, and targeting the production of IL-1β has proven to be a promising approach for atherosclerosis management in humans. Interestingly, the extent of injury after fulminant hepatitis or myocardial infarction is time-of-day dependent under the control of the clock, and chronotherapy represents a promising approach for the management of pathologies involving deregulation of NLRP3 signaling.

Circadian disruption with constant light exposure exacerbates atherosclerosis in male ApolipoproteinE-deficient mice

Disruption of the circadian system caused by disordered exposure to light is pervasive in modern society and increases the risk of cardiovascular disease. The mechanisms by which this happens are largely unknown. ApolipoproteinE-deficient (ApoE^−/−) mice are studied commonly to elucidate mechanisms of atherosclerosis. In this study, we determined the effects of light-induced circadian disruption on atherosclerosis in ApoE^−/− mice. We first characterized circadian rhythms of behavior, light responsiveness, and molecular timekeeping in tissues from ApoE^−/− mice that were indistinguishable from rhythms in ApoE^+/+ mice. These data showed that ApoE^−/− mice had no inherent circadian disruption and therefore were an appropriate model for our study. We next induced severe disruption of circadian rhythms by exposing ApoE^−/− mice to constant light for 12 weeks. Constant light exposure exacerbated atherosclerosis in male, but not female, ApoE^−/− mice. Male ApoE^−/− mice exposed to constant light had increased serum cholesterol concentrations due to increased VLDL/LDL fractions. Taken together, these data suggest that ApoE^−/− mice are an appropriate model for studying light-induced circadian disruption and that exacerbated dyslipidemia may mediate atherosclerotic lesion formation caused by constant light exposure.

High plasma levels of pro-inflammatory factors interleukin-17 and interleukin-23 are associated with poor outcome of cardiac-arrest patients: a single center experience

Background

Systemic inflammation is an important feature of post-cardiac arrest syndrome (PCAS). This study was designed to determine whether the plasma concentrations of some circulating pro-inflammatory cytokines (interleukin-17 [IL-8], IL-22, IL-23 and IL-33) are of value in predicting the outcome of patients after return of spontaneous circulation (ROSC) during the post–cardiac arrest period.

Methods

This was a prospective observational clinical study. In total, 21 patients (survivors, n = 10; non-survivors, n = 11) who experienced cardiac arrest and successful ROSC with expected survival of at least 7 days were consecutively enrolled from January 2016 to December 2017. Of the 21 enrolled patients, ten survived were designated “survivors”. The other eleven patients died between 2 days and 1 months post ROSC. Venous blood was drawn at three time-points: baseline (< 1 h post ROSC), 2 days post ROSC and 7 days post ROSC. Plasma IL-8, IL-22, IL-23 and IL-33 were determined using commercial enzyme-linked immunosorbent assays.

Results

Plasma creatinine levels, but aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, were elevated in non-survivors compared with survivors. Plasma levels of IL-17, IL-22, IL-23 and IL-33 of the 21 total patients did not change at 2 or 7 days post ROSC compared to baseline. In survivors, the plasma levels of IL-17 and IL-23 at 2 or 7 days post ROSC were lower than baseline. In non-survivors, plasma levels of IL-17 increased compared with baseline. Receiver operating characteristic curve analysis showed that the plasma levels of IL-17 and IL-23 at 2 or 7 days post ROSC were able to predict the mortality of PCAS patients, and positively correlated with Acute Physiology and Chronic Health Evaluation (APACHE)-II score and time to ROSC.

Conclusion

These results provide the first evidence that the elevated plasma IL-17 and IL-23 levels are associated with poor outcome in PCAS patients. The role of IL-17/IL-23 axis post ROSC is worth paying attention to in PCAS patients.

Trial registration

Clinicaltrial.govNCT02297776, 2014-11-21.

Disruption of circadian rhythm by alternating light-dark cycles aggravates atherosclerosis development in APOE*3-Leiden.CETP mice

Disruption of circadian rhythm by means of shift work has been associated with cardiovascular disease in humans. However, causality and underlying mechanisms have not yet been established. In this study, we exposed hyperlipidemic APOE*3-Leiden.CETP mice to either regular light-dark cycles, weekly 6 hours phase advances or delays, or weekly alternating light-dark cycles (12 hours shifts), as a well-established model for shift work. We found that mice exposed to 15 weeks of alternating light-dark cycles displayed a striking increase in atherosclerosis, with an approximately twofold increase in lesion size and severity, while mice exposed to phase advances and delays showed a milder circadian disruption and no significant effect on atherosclerosis development. We observed a higher lesion macrophage content in mice exposed to alternating light-dark cycles without obvious changes in plasma lipids, suggesting involvement of the immune system. Moreover, while no changes in the number or activation status of circulating monocytes and other immune cells were observed, we identified increased markers for inflammation, oxidative stress, and chemoattraction in the vessel wall. Altogether, this is the first study to show that circadian disruption by shifting light-dark cycles directly aggravates atherosclerosis development.