Short-term disruption of diurnal rhythms after murine myocardial infarction adversely affects long-term myocardial structure and function

Molecular subtypes of ischemic heart disease based on circadian rhythm

Coronary atherosclerotic heart disease (CAD) is among the most prevalent chronic diseases globally. Circadian rhythm disruption (CRD) is closely associated with the progression of various diseases. However, the precise role of CRD in the development of CAD remains to be elucidated. The Circadian rhythm disruption score (CRDscore) was employed to quantitatively assess the level of CRD in CAD samples. Our investigation revealed a significant association between high CRDscore and adverse prognosis in CAD patients, along with a substantial correlation with CAD progression. Remarkably distinct CRDscore distributions were also identified among various subtypes. In summary, we have pioneered the revelation of the relationship between CRD and CAD at the single-cell level and established reliable markers for the development, treatment, and prognosis of CAD. A deeper understanding of these mechanisms may offer new possibilities for incorporating "the therapy of coronary heart disease based circadian rhythm" into personalized medical treatment regimens.

One Health: Circadian Medicine Benefits Both Non-human Animals and Humans Alike

Circadian biology's impact on human physical health and its role in disease development and progression is widely recognized. The forefront of circadian rhythm research now focuses on translational applications to clinical medicine, aiming to enhance disease diagnosis, prognosis, and treatment responses. However, the field of circadian medicine has predominantly concentrated on human healthcare, neglecting its potential for transformative applications in veterinary medicine, thereby overlooking opportunities to improve non-human animal health and welfare. This review consists of three main sections. The first section focuses on the translational potential of circadian medicine into current industry practices of agricultural animals, with a particular emphasis on horses, broiler chickens, and laying hens. The second section delves into the potential applications of circadian medicine in small animal veterinary care, primarily focusing on our companion animals, namely dogs and cats. The final section explores emerging frontiers in circadian medicine, encompassing aquaculture, veterinary hospital care, and non-human animal welfare and concludes with the integration of One Health principles. In summary, circadian medicine represents a highly promising field of medicine that holds the potential to significantly enhance the clinical care and overall health of all animals, extending its impact beyond human healthcare.

Chronic circadian rhythm disorder induces heart failure with preserved ejection fraction-like phenotype through the Clock-sGC-cGMP-PKG1 signaling pathway

Emerging evidence has documented that circadian rhythm disorders could be related to cardiovascular diseases. However, there is limited knowledge on the direct adverse effects of circadian misalignment on the heart. This study aimed to investigate the effect of chronic circadian rhythm disorder on heart homeostasis in a mouse model of consistent jetlag. The jetlag model was induced in mice by a serial 8-h phase advance of the light cycle using a light-controlled isolation box every 4 days for up to 3 months. Herein, we demonstrated for the first time that chronic circadian rhythm disorder established in the mouse jetlag model could lead to HFpEF-like phenotype such as cardiac hypertrophy, cardiac fibrosis, and cardiac diastolic dysfunction, following the attenuation of the Clock-sGC-cGMP-PKG1 signaling. In addition, clock gene knock down in cardiomyocytes induced hypertrophy via decreased sGC-cGMP-PKG signaling pathway. Furthermore, treatment with an sGC-activator riociguat directly attenuated the adverse effects of jetlag model-induced cardiac hypertrophy, cardiac fibrosis, and cardiac diastolic dysfunction. Our data suggest that circadian rhythm disruption could induce HFpEF-like phenotype through downregulation of the clock-sGC-cGMP-PKG1 signaling pathway. sGC could be one of the molecular targets against circadian rhythm disorder-related heart disease.

Guanxin V alleviates ventricular remodeling after acute myocardial infarction with circadian disruption by regulating mitochondrial dynamics

PURPOSE

Circadian disruption has been a common issue due to modern lifestyles. Ventricular remodeling (VR) is a pivotal progressive pathologic change after acute myocardial infarction (AMI) and circadian disruption may have a negative influence on VR according to the latest research. Whether or not Guanxin V (GXV) has a positive effect on VR after AMI with circadian disruption drew our interest.

METHODS

Rats were randomly divided into a sham group, an AMI group, an AMI with circadian disruption group, and an AMI with circadian disruption treated with the GXV group according to a random number table. RNA sequencing (RNA-Seq) was utilized to confirm the different expressed genes regulated by circadian disruption. Cardiac function, inflammation factors, pathological evaluation, and mitochondrial dynamics after the intervention were conducted to reveal the mechanism by which GXV regulated VR after AMI with circadian disruption.

RESULTS

RNA-Seq demonstrated that NF-κB was up-regulated by circadian disruption in rats with AMI. Functional and pathological evaluation indicated that compared with the AMI group, circadian disruption was associcataed with deteriorated cardiac function, expanded infarcted size, and exacerbated fibrosis and cardiomyocyte apoptosis. Further investigation demonstrated that mitochondrial dynamics imbalance was induced by circadian disruption. GXV intervention reversed the inflammatory status including down-regulation of NF-κB. Reserved cardiac function, limited infarct size, and ameliorated fibrosis and apoptosis were also observed in the GXV treated group. GXV maintained mitochondrial fission/fusion imbalance through suppressed expression of mitochondrial fission-associated proteins.

CONCLUSION

The study findings suggest that identified mitochondrial dysfunctions may underlie the link between circadian disruption and VR. GXV may exert cardioprotection after AMI with circadian disruption through regulating mitochondrial dynamics.

Circadian Influences on Myocardial Ischemia-Reperfusion Injury and Heart Failure

The impact of circadian rhythms on cardiovascular function and disease development is well established, with numerous studies in genetically modified animals emphasizing the circadian molecular clock's significance in the pathogenesis and pathophysiology of myocardial ischemia and heart failure progression. However, translational preclinical studies targeting the heart's circadian biology are just now emerging and are leading to the development of a novel field of medicine termed circadian medicine. In this review, we explore circadian molecular mechanisms and novel therapies, including (1) intense light, (2) small molecules modulating the circadian mechanism, and (3) chronotherapies such as cardiovascular drugs and meal timings. These promise significant clinical translation in circadian medicine for cardiovascular disease. (4) Additionally, we address the differential functioning of the circadian mechanism in males versus females, emphasizing the consideration of biological sex, gender, and aging in circadian therapies for cardiovascular disease.

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.

Pioneering new frontiers in circadian medicine chronotherapies for cardiovascular health

Cardiovascular disease (CVD) is a global health concern. Circadian medicine improves cardiovascular care by aligning treatments with our body's daily rhythms and their underlying cellular circadian mechanisms. Time-based therapies, or chronotherapies, show special promise in clinical cardiology. They optimize treatment schedules for better outcomes with fewer side effects by recognizing the profound influence of rhythmic body cycles. In this review, we focus on three chronotherapy areas (medication, light, and meal timing) with potential to enhance cardiovascular care. We also highlight pioneering research in the new field of rest, the gut microbiome, novel chronotherapies for hypertension, pain management, and small molecules that targeting the circadian mechanism.

The Cardiac Circadian Clock: Implications for Cardiovascular Disease and its Treatment

Virtually all aspects of physiology fluctuate with respect to the time of day. This is beautifully exemplified by cardiovascular physiology, for which blood pressure and electrophysiology exhibit robust diurnal oscillations. At molecular/biochemical levels (eg, transcription, translation, signaling, metabolism), cardiovascular-relevant tissues (such as the heart) are profoundly different during the day vs the night. Unfortunately, this in turn contributes toward 24-hour rhythms in both risk of adverse event onset (eg, arrhythmias, myocardial infarction) and pathogenesis severity (eg, extent of ischemic damage). Accumulating evidence indicates that cell-autonomous timekeeping mechanisms, termed circadian clocks, temporally govern biological processes known to play critical roles in cardiovascular function/dysfunction. In this paper, a comprehensive review of our current understanding of the cardiomyocyte circadian clock during both health and disease is detailed. Unprecedented basic, translational, and epidemiologic studies support a need to implement chronobiological considerations in strategies designed for both prevention and treatment of cardiovascular disease.

Circadian Disruption and the Molecular Clock in Atherosclerosis and Hypertension

Circadian rhythms are crucial for maintaining vascular function and disruption of these rhythms are associated with negative health outcomes including cardiovascular disease and hypertension. Circadian rhythms are regulated by the central clock within the suprachiasmatic nucleus of the hypothalamus and peripheral clocks located in nearly every cell type in the body, including cells within the heart and vasculature. In this review, we summarize the most recent preclinical and clinical research linking circadian disruption, with a focus on molecular circadian clock mechanisms, in atherosclerosis and hypertension. Furthermore, we provide insight into potential future chronotherapeutics for hypertension and vascular disease. A better understanding of the influence of daily rhythms in behaviour, such as sleep/wake cycles, feeding, and physical activity, as well as the endogenous circadian system on cardiovascular risk will help pave the way for targeted approaches in atherosclerosis and hypertension treatment/prevention.

Associations of sleep quality and exercise frequency and the risk of coronary heart disease in Chinese urban elderly: a secondary analysis of cross-sectional data

BACKGROUND

Sleep quality and exercise frequency are closely associated with coronary heart disease (CHD). Few studies focused on the joint effect of initiating sleep, sleep disorders, and exercise frequency on the risk of CHD in the elderly. We used a secondary data analysis based on Boshan Elderly cross-sectional study. We explored the sleep quality, exercise frequency, and their joint effects on the risk of CHD.

METHODS

We collected 678 participants whose age ≥ 60 years old from Boshan District Hospital. We used the Pittsburgh Sleep Quality Index to evaluate the sleep quality and obtained physical examination information from the hospital.

RESULTS

Compared with the non-CHD group, patients with CHD spent more time in initiating sleep (time ≥ 60 min, 34.59% vs. 22.93%, P = 0.025) and less time exercising (exercise frequency < 1 times/week, 23.90% vs. 17.15%, P = 0.024). In multiple logistic regression analysis, sleep latency ≥ 60 min was associated with CHD risk (adjusted OR = 1.83; 95% CI: 1.11, 2.99; P-trend = 0.008). The adjusted OR (95% CI) of CHD was 2.24 (1.16, 4.34) for sleep duration < 5 h versus 5-9 h. Compared with exercise frequency < 1 times/week, the adjusted OR for exercise frequency ≥ 1 times/week was 0.46 (95% CI: 0.26, 0.83; P = 0.010). In addition, the joint effects of long sleep latency (≥ 60 min) and sleep disorders were associated with CHD (adjusted OR = 3.36; 95% CI: 1.41, 8.02). The joint effect of exercise frequency ≥ 1 times/week and sleep onset latency within normal limits (< 30 min) was also associated with CHD, and the adjusted OR (95% CI) was 0.42 (0.21, 0.87).

CONCLUSIONS

Long sleep latency, high frequency of initiating sleep difficulty, sleep disorders, and short sleep duration were positively associated with CHD. In addition, the joint effects of long sleep latency and sleep disorders were positively correlated with CHD incidence. However, the joint effects of exercise frequency ≥ 1 times/week and normal sleep onset latency were negatively associated CHD.

The Role of the Circadian Rhythm in Dyslipidaemia and Vascular Inflammation Leading to Atherosclerosis

Cardiovascular diseases (CVD) are among the leading causes of death worldwide. Many lines of evidence suggest that the disturbances in circadian rhythm are responsible for the development of CVDs; however, circadian misalignment is not yet a treatable trait in clinical practice. The circadian rhythm is controlled by the central clock located in the suprachiasmatic nucleus and clock genes (molecular clock) located in all cells. Dyslipidaemia and vascular inflammation are two hallmarks of atherosclerosis and numerous experimental studies conclude that they are under direct influence by both central and molecular clocks. This review will summarise the results of experimental studies on lipid metabolism, vascular inflammation and circadian rhythm, and translate them into the pathophysiology of atherosclerosis and cardiovascular disease. We discuss the effect of time-respected administration of medications in cardiovascular medicine. We review the evidence on the effect of bright light and melatonin on cardiovascular health, lipid metabolism and vascular inflammation. Finally, we suggest an agenda for future research and recommend on clinical practice.

Disturbance of suprachiasmatic nucleus function improves cardiac repair after myocardial infarction by IGF2-mediated macrophage transition

Suprachiasmatic nucleus (SCN) in mammals functions as the master circadian pacemaker that coordinates temporal organization of physiological processes with the environmental light/dark cycles. But the causative links between SCN and cardiovascular diseases, specifically the reparative responses after myocardial infarction (MI), remain largely unknown. In this study we disrupted mouse SCN function to investigate the role of SCN in cardiac dysfunction post-MI. Bilateral ablation of the SCN (SCNx) was generated in mice by electrical lesion; myocardial infarction was induced via ligation of the mid-left anterior descending artery (LAD); cardiac function was assessed using echocardiography. We showed that SCN ablation significantly alleviated MI-induced cardiac dysfunction and cardiac fibrosis, and promoted angiogenesis. RNA sequencing revealed differentially expressed genes in the heart of SCNx mice from D0 to D3 post-MI, which were functionally associated with the inflammatory response and cytokine-cytokine receptor interaction. Notably, the expression levels of insulin-like growth factor 2 (Igf2) in the heart and serum IGF2 concentration were significantly elevated in SCNx mice on D3 post-MI. Stimulation of murine peritoneal macrophages in vitro with serum isolated from SCNx mice on D3 post-MI accelerated the transition of anti-inflammatory macrophages, while antibody-mediated neutralization of IGF2 receptor blocked the macrophage transition toward the anti-inflammatory phenotype in vitro as well as the corresponding cardioprotective effects observed in SCNx mice post-MI. In addition, disruption of mouse SCN function by exposure to a desynchronizing condition (constant light) caused similar protective effects accompanied by elevated IGF2 expression on D3 post-MI. Finally, mice deficient in the circadian core clock genes (Ckm-cre; Bmal1f/f mice or Per1/2 double knockout) did not lead to increased serum IGF2 concentration and showed no protective roles in post-MI, suggesting that the cardioprotective effect observed in this study was mediated particularly by the SCN itself, but not by self-sustained molecular clock. Together, we demonstrate that inhibition of SCN function promotes Igf2 expression, which leads to macrophage transition and improves cardiac repair post-MI.

Rev-erbα agonist SR9009 protects against cerebral ischemic injury through mechanisms involving Nrf2 pathway

Backgrounds: The circadian clock protein Rev-erbα is a crucial regulator of circadian rhythms that affects multiple molecular, cellular, and physiology pathways that control susceptibility, injury, and recovery in the neurological disorders. Emerging evidence suggest that Rev-erbα plays a key role in the inflammation and oxidative stress, two pivotal mechanisms in the pathogenesis, progression, and recovery process of ischemic stroke. However, it remains inconclusive whether Rev-erbα activation is protective against ischemic brain damage. Nuclear factor erythroid 2-related factor 2 (Nrf2) pathway, a master regulator of inflammatory and oxidative responses. Our study aimed to determine whether pharmacological activation of Rev-erbα by SR9009 protects against acute ischemic brain damage partly via Nrf2 pathway.

Methods: Adult mice were pretreated with SR9009 or Nrf2 inhibitor all-trans-retinoic acid (ATRA) for 3 days prior to Sham or middle cerebral artery occlusion (MCAO) operation. After ischemia for 1 h and reperfusion for 24 h, the neurological function and cerebral infarction volume were determined, superoxide dismutase (SOD) activity, malondialdehyde (MDA) content and glutathione peroxidase (GSH-PX) activity in serum were detected by kit. The mRNA and/or protein level of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), inducible nitric oxide synthase (iNOS), Period (Per)1, Brain and muscle arnt-like1 (Bmal1), Circadian locomotor output cycles kaput (Clock), Rev-erbα, Nrf2, heme oxygenase-1 (HO-1) and quinone oxidoreductase 1 (NQO1) in cerebral cortex were detected by q-PCR and Western blot.

Results: We confirmed that SR9009 activated Rev-erbα gene in the cerebral cortex under basal condition. At 24 h after reperfusion, SR9009 ameliorated acute neurological deficits, reduced infarct volume. Meanwhile, the inflammatory TNF-α, IL-1β, iNOS and MDA content levels were significant decreased, SOD and GSH-PX activity were obviously increased, which were markedly blunted (or abolished) by ATRA. SR9009 enhanced the induction of Nrf2 and its downstream target genes HO-1 and NQO1 after ischemic insult. In addition, we found that SR9009 restored Rev-erbα, Bmal1, Clock, Per1 genes expression in the cerebral cortex under ischemic condition.

Conclusion: Taken together, Rev-erbα activation by SR9009 protects against ischemic stroke damage, at least, partly through Nrf2 pathway.

Melatonin Treatment in Kidney Diseases

Melatonin is a neurohormone that is mainly secreted by the pineal gland. It coordinates the work of the superior biological clock and consequently affects many processes in the human body. Disorders of the waking and sleeping period result in nervous system imbalance and generate metabolic and endocrine derangements. The purpose of this review is to provide information regarding the potential benefits of melatonin use, particularly in kidney diseases. The impact on the cardiovascular system, diabetes, and homeostasis causes melatonin to be indirectly connected to kidney function and quality of life in people with chronic kidney disease. Moreover, there are numerous reports showing that melatonin plays a role as an antioxidant, free radical scavenger, and cytoprotective agent. This means that the supplementation of melatonin can be helpful in almost every type of kidney injury because inflammation, apoptosis, and oxidative stress occur, regardless of the mechanism. The administration of melatonin has a renoprotective effect and inhibits the progression of complications connected to renal failure. It is very important that exogenous melatonin supplementation is well tolerated and that the number of side effects caused by this type of treatment is low.

Toward Precision Medicine: Circadian Rhythm of Blood Pressure and Chronotherapy for Hypertension - 2021 NHLBI Workshop Report

Healthy individuals exhibit blood pressure variation over a 24-hour period with higher blood pressure during wakefulness and lower blood pressure during sleep. Loss or disruption of the blood pressure circadian rhythm has been linked to adverse health outcomes, for example, cardiovascular disease, dementia, and chronic kidney disease. However, the current diagnostic and therapeutic approaches lack sufficient attention to the circadian rhythmicity of blood pressure. Sleep patterns, hormone release, eating habits, digestion, body temperature, renal and cardiovascular function, and other important host functions as well as gut microbiota exhibit circadian rhythms, and influence circadian rhythms of blood pressure. Potential benefits of nonpharmacologic interventions such as meal timing, and pharmacologic chronotherapeutic interventions, such as the bedtime administration of antihypertensive medications, have recently been suggested in some studies. However, the mechanisms underlying circadian rhythm-mediated blood pressure regulation and the efficacy of chronotherapy in hypertension remain unclear. This review summarizes the results of the National Heart, Lung, and Blood Institute workshop convened on October 27 to 29, 2021 to assess knowledge gaps and research opportunities in the study of circadian rhythm of blood pressure and chronotherapy for hypertension.

Identification of the potential biomarkers associated with circadian rhythms in heart failure

Background

Heart failure (HF) is a syndrome with multiple clinical symptoms resulting from damage to the heart's structure and/or function with various pathogenic factors, which has developed as one of the most severe threats to human health. Approximately 13% of genes and about 8% of proteins contained in the heart are rhythmic, which could lead to HF if disrupted. Herein, we aimed to identify the circadian rhythms-related hub genes as potential biomarkers contributing to the identification and treatment of HF.

Methods

Expression data of ischemic and dilated cardiomyopathy samples with or without HF were collected from the GEO database. First, genes with differential expression in HF and healthy samples were identified, named as differentially expressed genes (DEGs), which were then intersected with circadian rhythms-related genes to identify circadian rhythms-related DEGs. A protein-protein interaction (PPI) network was established to screen hub genes. The performance of the hub genes to identify HF among healthy controls was assessed by referring to the receiver operating characteristic (ROC) curve. Additionally, quantitative real-time polymerase chain reaction (RT-PCR) was run to further validate the hub genes depending on clinical human peripheral blood samples.

Results

A total of 10,163 DEGs were determined, composed of 4,615 up-regulated genes and 5,548 down-regulated genes in HF patients in comparison to healthy controls. By overlapping the circadian rhythms-related genes in the Circadian Gene DataBase (CGDB), 723 circadian rhythms-related DEGs were obtained, mainly enriched in regulating lipid metabolic process, circadian rhythm and AMPK signaling pathway. Eight hub genes were screened out through the PPI network. The ROC curve indicated the high accuracy of five hub genes with AUC > 0.7, which also showed high accuracy validated by the external validation dataset. Furthermore, according to the results of quantitative RT-PCR, the HF group showed significantly increased relative mRNA expression of CRY2 and BHLHE41 while the decreased ARNTL and NPAS2 in comparison to controls, indicating the four hub genes as potential biomarkers of HF.

Conclusion

Our study validated that ARNTL, CRY2, BHLHE41 and NPAS2 could serve as potential biomarkers of circadian rhythm in HF. These results may provide a reference for employing novel markers or targets for the diagnosis and treatment of HF.

The Circadian Biology of Heart Failure

Driven by autonomous molecular clocks that are synchronized by a master pacemaker in the suprachiasmatic nucleus, cardiac physiology fluctuates in diurnal rhythms that can be partly or entirely circadian. Cardiac contractility, metabolism, and electrophysiology, all have diurnal rhythms, as does the neurohumoral control of cardiac and kidney function. In this review, we discuss the evidence that circadian biology regulates cardiac function, how molecular clocks may relate to the pathogenesis of heart failure, and how chronotherapeutics might be applied in heart failure. Disrupting molecular clocks can lead to heart failure in animal models, and the myocardial response to injury seems to be conditioned by the time of day. Human studies are consistent with these findings, and they implicate the clock and circadian rhythms in the pathogenesis of heart failure. Certain circadian rhythms are maintained in patients with heart failure, a factor that can guide optimal timing of therapy. Pharmacologic and nonpharmacologic manipulation of circadian rhythms and molecular clocks show promise in the prevention and treatment of heart failure.

Cardiac System during the Aging Process

The aging process is accompanied by a continuous decline of the cardiac system, disrupting the homeostatic regulation of cells, organs, and systems. Aging increases the prevalence of cardiovascular diseases, thus heart failure and mortality. Understanding the cardiac aging process is of pivotal importance once it allows us to design strategies to prevent age-related cardiac events and increasing the quality of live in the elderly. In this review we provide an overview of the cardiac aging process focus on the following topics: cardiac structural and functional modifications; cellular mechanisms of cardiac dysfunction in the aging; genetics and epigenetics in the development of cardiac diseases; and aging heart and response to the exercise.

Circadian regulation of cardiac muscle function and protein degradation

The circadian clock plays a fundamental role in physiology. In particular, the heart is a target organ where the clock orchestrates various aspects of cardiac function. At the molecular level, the clock machinery governs daily rhythms of gene expression. Such circadian regulation is in tune with the dynamic nature of heart structure and function, and provides the foundation for chronotherapeutic applications in cardiovascular diseases. In comparison, a regulatory role of the clock in cardiac protein degradation is poorly documented. Sarcomere is the structural and functional unit responsible for cardiac muscle contraction, and sarcomere components are closely regulated by protein folding and proteolysis. Emerging evidence supports a role of the circadian clock in governing sarcomere integrity and function. Particularly, recent studies uncovered a circadian regulation of a core sarcomere component TCAP. It is possible that circadian regulation of the cardiac muscle protein turnover is a key regulatory mechanism underlying cardiac remodeling in response to physiological and environmental stimuli. While the detailed regulatory mechanisms and the molecular links to cardiac (patho)physiology remain to be further studied, therapeutic strategies targeting circadian control in the heart may markedly enhance intervention outcomes against cardiovascular disease.

A brief morning rest period benefits cardiac repair in pressure overload hypertrophy and postmyocardial infarction

Rest has long been considered beneficial to patient healing; however, remarkably, there are no evidence-based experimental models determining how it benefits disease outcomes. Here, we created an experimental rest model in mice that briefly extends the morning rest period. We found in 2 major cardiovascular disease conditions (cardiac hypertrophy, myocardial infarction) that imposing a short, extended period of morning rest each day limited cardiac remodeling compared with controls. Mechanistically, rest mitigates autonomic-mediated hemodynamic stress on the cardiovascular system, relaxes myofilament contractility, and attenuates cardiac remodeling genes, consistent with the benefits on cardiac structure and function. These same rest-responsive gene pathways underlie the pathophysiology of many major human cardiovascular conditions, as demonstrated by interrogating open-source transcriptomic data; thus, patients with other conditions may also benefit from a morning rest period in a similar manner. Our findings implicate rest as a key driver of physiology, creating a potentially new field - as broad and important as diet, sleep, or exercise - and provide a strong rationale for investigation of rest-based therapy for major clinical diseases.

Melatonin improves cardiac remodeling and brain-heart sympathetic hyperactivation aggravated by light disruption after myocardial infarction

Light in the external environment might affect cardiovascular function. The light disruption seems to be related to changes in cardiovascular physiological functions, and disturbing light may be a risk factor for cardiovascular diseases. Prior studies have found that light disruption after myocardial infarction (MI) exacerbates cardiac remodeling, and the brain-heart sympathetic nervous system may be one of the key mechanisms. However, how to improve light-disrupted cardiac remodeling remains unclear. Melatonin is an indoleamine secreted by the pineal gland and controlled by endogenous circadian oscillators within the suprachiasmatic nucleus, which is closely associated with light/dark cycle. This study aimed to explore whether melatonin could improve light-disrupted cardiac remodeling and modulate the brain-heart sympathetic nervous system. Our study revealed that light disruption reduced serum melatonin levels, aggravated cardiac sympathetic remodeling, caused overactivation of the brain-heart sympathetic nervous system, exacerbated cardiac dysfunction, and increased cardiac fibrosis after MI, while melatonin treatment improved light disruption-exacerbated cardiac remodeling and brain-heart sympathetic hyperactivation after MI. Furthermore, RNA-Seq results revealed the significant changes at the cardiac transcription level. In conclusion, melatonin may be a potential therapy for light-disrupted cardiac remodeling.

Sodium–Glucose cotransporter 2 inhibitor empagliflozin decreases ventricular arrhythmia susceptibility by alleviating electrophysiological remodeling post-myocardial-infarction in mice

Background: Recent clinical trials indicate that sodium–glucose cotransporter 2 (SGLT2) inhibitors improve cardiovascular outcomes in myocardial infarction (MI) patients, but the underlying mechanisms remain unknown. As arrhythmia often occurs during myocardial infarction, it is the main cause of death.

Objective: The purpose of this study was to investigate the influence of empagliflozin (EMPA), an SGLT2 inhibitor, on cardiac electrophysiological remodeling and arrhythmia susceptibility of myocardial infarction mice.

Methods: ECG was obtained from mice 1 week after MI to determine the QT interval. In an electrophysiological study and optical mapping was performed to evaluate the function of EMPA and underlying mechanisms of post-myocardial-infarction in mice.

Results: EMPA treatment significantly reduced the QT interval of MI mice (MI + EMPA 50.24 ms vs. MI 64.68 ms). The membrane potential and intracellular Ca [Ca_i] were mapped from 13 MI hearts and five normal hearts using an optical mapping technique. A dynamic pacing protocol was used to determine action potential duration and [Ca_i] at baseline and after EMPA (10 umol/L) infusion. EMPA perfusion did not change the APD₈₀ and CaT₈₀ in normal ventricles while shortening them in an infarct zone, bordering zone, and remote zone of MI hearts at 200 ms, 150 ms, 120 ms, and 100 ms pacing cycle length. The conduction velocity of infarcted ventricles was 0.278 m/s and 0.533 m/s in normal ventricles at baseline (p < 0.05). After EMPA administration, the conduction velocity of infarcted ventricles increased to 0.363 m/s, whereas no significant changes were observed in normal ventricles. The action potential rise time, CaT rise time, and CaT tau time were improved after EMPA perfusion in infarcted ventricles, whereas no significant changes were observed in normal ventricles. EMPA decreases early afterdepolarizations premature ventricular beats, and ventricular fibrillation (VF) in infarcted ventricles. The number of phase singularities (baseline versus EMPA, 6.26 versus 3.25), dominant frequency (20.52 versus 10.675 Hz), and ventricular fibrillation duration (1.072 versus 0.361 s) during ventricular fibrillation in infarcted ventricles were all significantly decreased by EMPA.

Conclusion: Treatment with EMPA improved post-MI electrophysiological remodeling and decreased substrate for VF of MI mice. The inhibitors of SGLT2 may be a new class of agents for the prevention of ventricle arrhythmia after chronic MI.

Redox Regulatory Changes of Circadian Rhythm by the Environmental Risk Factors Traffic Noise and Air Pollution

Significance: Risk factors in the environment such as air pollution and traffic noise contribute to the development of chronic noncommunicable diseases. Recent Advances: Epidemiological data suggest that air pollution and traffic noise are associated with a higher risk for cardiovascular, metabolic, and mental disease, including hypertension, heart failure, myocardial infarction, diabetes, arrhythmia, stroke, neurodegeneration, depression, and anxiety disorders, mainly by activation of stress hormone signaling, inflammation, and oxidative stress. Critical Issues: We here provide an in-depth review on the impact of the environmental risk factors air pollution and traffic noise exposure (components of the external exposome) on cardiovascular health, with special emphasis on the role of environmentally triggered oxidative stress and dysregulation of the circadian clock. Also, a general introduction on the contribution of circadian rhythms to cardiovascular health and disease as well as a detailed mechanistic discussion of redox regulatory pathways of the circadian clock system is provided. Future Directions: Finally, we discuss the potential of preventive strategies or "chrono" therapy for cardioprotection. Antioxid. Redox Signal. 37, 679-703.

Circadian rhythms in ischaemic heart disease: key aspects for preclinical and translational research: position paper of the ESC working group on cellular biology of the heart

Circadian rhythms are internal regulatory processes controlled by molecular clocks present in essentially every mammalian organ that temporally regulate major physiological functions. In the cardiovascular system, the circadian clock governs heart rate, blood pressure, cardiac metabolism, contractility, and coagulation. Recent experimental and clinical studies highlight the possible importance of circadian rhythms in the pathophysiology, outcome, or treatment success of cardiovascular disease, including ischaemic heart disease. Disturbances in circadian rhythms are associated with increased cardiovascular risk and worsen outcome. Therefore, it is important to consider circadian rhythms as a key research parameter to better understand cardiac physiology/pathology, and to improve the chances of translation and efficacy of cardiac therapies, including those for ischaemic heart disease. The aim of this Position Paper by the European Society of Cardiology Working Group Cellular Biology of the Heart is to highlight key aspects of circadian rhythms to consider for improvement of preclinical and translational studies related to ischaemic heart disease and cardioprotection. Applying these considerations to future studies may increase the potential for better translation of new treatments into successful clinical outcomes.

SDF-1/CXCR4-Mediated Stem Cell Mobilization Involved in Cardioprotective Effects of Electroacupuncture on Mouse with Myocardial Infarction

Stem cell-based therapeutic strategies have obtained a significant breakthrough in the treatment of cardiovascular diseases, particularly in myocardial infarction (MI). Nevertheless, limited retention and poor migration of stem cells are still problems for stem cell therapeutic development. Hence, there is an urgent need to develop new strategies that can mobilize stem cells to infarcted myocardial tissues effectively. Electroacupuncture (EA) intervention can improve cardiac function and alleviate myocardial injury after MI, but its molecular mechanism is still unclear. This study is aimed at observing the effects of EA treatment on the stem cell mobilization and revealing possible mechanisms in the MI model of mice. EA treatment at Neiguan (PC6) and Xinshu (BL15) acupoints was conducted on the second day after the ligation surgery. Then, the number of stem cells in peripheral blood after EA in MI mice and their cardiac function, infarct size, and collagen deposition was observed. We found that the number of CD34-, CD117-, Sca-1-, and CD90-positive cells increased at 6 h and declined at 24 h after EA intervention in the blood of MI mice. The expression of CXC chemokine receptor-4 (CXCR4) protein was upregulated at 6 h after EA treatment, while the ratio of LC3B II/I or p-ERK/ERK showed a reverse trend. In addition, there was obvious difference in EF and FS between wild-type mice and CXCR4+/− mice. The infarct size, collagen deposition, and apoptosis of the injured myocardium in CXCR4+/− mice increased but could be ameliorated by EA. In a word, our study demonstrates that EA alleviates myocardial injury via stem cell mobilization which may be regulated by the SDF-1/CXCR4 axis.

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.

Postnatal Deletion of Bmal1 in Cardiomyocyte Promotes Pressure Overload Induced Cardiac Remodeling in Mice

Background Mice with cardiomyocyte-specific deletion of Bmal1, a core clock gene, had spontaneous abnormal cardiac metabolism, dilated cardiomyopathy, and shortened lifespan. However, the role of cardiomyocyte Bmal1 in pressure overload induced cardiac remodeling is unknown. Here we aimed to understand the contribution of cardiomyocyte Bmal1 to cardiac remodeling in response to pressure overload induced by transverse aortic constriction or chronic angiotensin Ⅱ (AngⅡ) infusion. Methods and Results By generating a tamoxifen-inducible cardiomyocyte-specific Bmal1 knockout mouse line (cKO) and challenging the mice with transverse aortic constriction or AngⅡ, we found that compared to littermate controls, the cKO mice displayed remarkably increased cardiac hypertrophy and augmented fibrosis both after transverse aortic constriction and AngⅡ induction, as assessed by echocardiographic, gravimetric, histologic, and molecular analyses. Mechanistically, RNA-sequencing analysis of the heart after transverse aortic constriction exposure revealed that the PI3K/AKT signaling pathway was significantly activated in the cKOs. Consistent with the in vivo findings, in vitro study showed that knockdown of Bmal1 in cardiomyocytes significantly promoted phenylephrine-induced cardiomyocyte hypertrophy and triggered fibroblast-to-myofibroblast differentiation, while inhibition of AKT remarkedly reversed the pro-hypertrophy and pro-fibrosis effects of Bmal1 knocking down. Conclusions These results suggest that postnatal deletion of Bmal1 in cardiomyocytes may promote pressure overload-induced cardiac remodeling. Moreover, we identified PI3K/AKT signaling pathway as the potential mechanistic ties between Bmal1 and cardiac remodeling.

Circadian Dependence of the Acute Immune Response to Myocardial Infarction

Circadian rhythms influence the recruitment of immune cells and the onset of inflammation, which is pivotal in the response to ischemic cardiac injury after a myocardial infarction (MI). The hyperacute immune response that occurs within the first few hours after a MI has not yet been elucidated. Therefore, we characterized the immune response and myocardial damage 3 hours after a MI occurs over a full twenty-four-hour period to investigate the role of the circadian rhythms in this response. MI was induced at Zeitgeber Time (ZT) 2, 8, 14, and 20 by permanent ligation of the left anterior descending coronary artery. Three hours after surgery, animals were terminated and blood and hearts collected to assess the immunological status and cardiac damage. Blood leukocyte numbers varied throughout the day, peaking during the rest-phase (ZT2 and 8). Extravasation of leukocytes was more pronounced during the active-phase (ZT14 and 20) and was associated with greater chemokine release to the blood and expression of adhesion molecules in the heart. Damage to the heart, measured by Troponin-I plasma levels, was elevated during this time frame. Clock gene oscillations remained intact in both MI-induced and sham-operated mice hearts, which could explain the circadian influence of the hyperacute inflammatory response after a MI. These findings are in line with the clinical observation that patients who experience a MI early in the morning (i.e., early active phase) have worse clinical outcomes. This study provides further insight on the immune response occurring shortly after an MI, which may contribute to the development of novel and optimization of current therapeutic approaches.

The Impact of Sex, Circadian Disruption, and the ClockΔ19/Δ19 Genotype on Alcohol Drinking in Mice

Shift work is associated with increased alcohol drinking, more so in males than females, and is thought to be a coping mechanism for disrupted sleep cycles. However, little is presently known about the causal influence of circadian rhythm disruptions on sex differences in alcohol consumption. In this study, we disrupted circadian rhythms in female and male mice using both environmental (i.e., shifting diurnal cycles) and genetic (i.e., Clock^Δ19/Δ19 mutation) manipulations, and measured changes in alcohol consumption and preference using a two-bottle choice paradigm. Alcohol consumption and preference, as well as food and water consumption, total caloric intake, and weight were assessed in adult female and male Clock^Δ19/Δ19 mutant mice or wild-type (WT) litter-mates, housed under a 12-hour:12-hour light:dark (L:D) cycle or a shortened 10-hour:10-hour L:D cycle. Female WT mice (under both light cycles) increased their alcohol consumption and preference over time, a pattern not observed in male WT mice. Compared to WT mice, Clock^Δ19/Δ19 mice displayed increased alcohol consumption and preference. Sex differences were not apparent in Clock^Δ19/Δ19 mice, with or without shifting diurnal cycles. In conclusion, sex differences in alcohol consumption patterns are evident and increase with prolonged access to alcohol. Disrupting circadian rhythms by mutating the Clock gene greatly increases alcohol consumption and abolishes sex differences present in WT animals.

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.

Improving Diuretic Response in Heart Failure by Implementing a Patient-Tailored Variability and Chronotherapy-Guided Algorithm

Heart failure is a major public health problem, which is associated with significant mortality, morbidity, and healthcare expenditures. A substantial amount of the morbidity is attributed to volume overload, for which loop diuretics are a mandatory treatment. However, the variability in response to diuretics and development of diuretic resistance adversely affect the clinical outcomes. Morevoer, there exists a marked intra- and inter-patient variability in response to diuretics that affects the clinical course and related adverse outcomes. In the present article, we review the mechanisms underlying the development of diuretic resistance. The role of the autonomic nervous system and chronobiology in the pathogenesis of congestive heart failure and response to therapy are also discussed. Establishing a novel model for overcoming diuretic resistance is presented based on a patient-tailored variability and chronotherapy-guided machine learning algorithm that comprises clinical, laboratory, and sensor-derived inputs, including inputs from pulmonary artery measurements. Inter- and intra-patient signatures of variabilities, alterations of biological clock, and autonomic nervous system responses are embedded into the algorithm; thus, it may enable a tailored dose regimen in a continuous manner that accommodates the highly dynamic complex system.

Mitochondrial autophagy and cell survival is regulated by the circadian Clock gene in cardiac myocytes during ischemic stress

Cardiac function is highly reliant on mitochondrial oxidative metabolism and quality control. The circadian Clock gene is critically linked to vital physiological processes including mitochondrial fission, fusion and bioenergetics; however, little is known of how the Clock gene regulates these vital processes in the heart. Herein, we identified a putative circadian CLOCK-mitochondrial interactome that gates an adaptive survival response during myocardial ischemia. We show by transcriptome and gene ontology mapping in CLOCK Δ19/Δ19 mouse that Clock transcriptionally coordinates the efficient removal of damaged mitochondria during myocardial ischemia by directly controlling transcription of genes required for mitochondrial fission, fusion and macroautophagy/autophagy. Loss of Clock gene activity impaired mitochondrial turnover resulting in the accumulation of damaged reactive oxygen species (ROS)-producing mitochondria from impaired mitophagy. This coincided with ultrastructural defects to mitochondria and impaired cardiac function. Interestingly, wild type CLOCK but not mutations of CLOCK defective for E-Box binding or interaction with its cognate partner ARNTL/BMAL-1 suppressed mitochondrial damage and cell death during acute hypoxia. Interestingly, the autophagy defect and accumulation of damaged mitochondria in CLOCK-deficient cardiac myocytes were abrogated by restoring autophagy/mitophagy. Inhibition of autophagy by ATG7 knockdown abrogated the cytoprotective effects of CLOCK. Collectively, our results demonstrate that CLOCK regulates an adaptive stress response critical for cell survival by transcriptionally coordinating mitochondrial quality control mechanisms in cardiac myocytes. Interdictions that restore CLOCK activity may prove beneficial in reducing cardiac injury in individuals with disrupted circadian CLOCK.Abbreviations: ARNTL/BMAL1: aryl hydrocarbon receptor nuclear translocator-like; ATG14: autophagy related 14; ATG7: autophagy related 7; ATP: adenosine triphosphate; BCA: bovine serum albumin; BECN1: beclin 1, autophagy related; bHLH: basic helix- loop-helix; CLOCK: circadian locomotor output cycles kaput; CMV: cytomegalovirus; COQ5: coenzyme Q5 methyltransferase; CQ: chloroquine; CRY1: cryptochrome 1 (photolyase-like); DNM1L/DRP1: dynamin 1-like; EF: ejection fraction; EM: electron microscopy; FS: fractional shortening; GFP: green fluorescent protein; HPX: hypoxia; i.p.: intraperitoneal; I-R: ischemia-reperfusion; LAD: left anterior descending; LVIDd: left ventricular internal diameter diastolic; LVIDs: left ventricular internal diameter systolic; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MFN2: mitofusin 2; MI: myocardial infarction; mPTP: mitochondrial permeability transition pore; NDUFA4: Ndufa4, mitochondrial complex associated; NDUFA8: NADH: ubiquinone oxidoreductase subunit A8; NMX: normoxia; OCR: oxygen consumption rate; OPA1: OPA1, mitochondrial dynamin like GTPase; OXPHOS: oxidative phosphorylation; PBS: phosphate-buffered saline; PER1: period circadian clock 1; PPARGC1A/PGC-1α: peroxisome proliferative activated receptor, gamma, coactivator 1 alpha; qPCR: quantitative real-time PCR; RAB7A: RAB7, member RAS oncogene family; ROS: reactive oxygen species; RT: room temperature; shRNA: short hairpin RNA; siRNA: small interfering RNA; TFAM: transcription factor A, mitochondrial; TFEB: transcription factor EB; TMRM: tetra-methylrhodamine methyl ester perchlorate; WT: wild -type; ZT: zeitgeber time.

Sympathetic Nervous System Mediates Cardiac Remodeling After Myocardial Infarction in a Circadian Disruption Model

Background: Circadian rhythms have a considerable impact on the daily physiology of the heart, and their disruption causes pathology. Several studies have revealed that circadian disruption impaired cardiac remodeling after myocardial infarction (MI); however, the underlying brain-heart mechanisms remain unknown. We aim to discuss whether circadian disruption facilitates cardiac remodeling after MI by activating sympathetic nervous system.

Methods: Rats were randomly divided into three groups: Sham group (Sham), MI group (MI), and MI+ circadian disruption group (MI+Dis); rats were treated with pseudorabies virus (PRV) injections for trans-synaptic retrograde tracing; rats were randomly divided into two groups: MI+ circadian disruption + Empty Vector+ clozapine N-oxide (CNO) (Empty Vector), and MI+ circadian disruption + hM4D(Gi)+ CNO [hM4D(Gi)].

Results: Circadian disruption significantly facilitated cardiac remodeling after MI with lower systolic function, larger left ventricular volume, and aggravated cardiac fibrosis. Cardiac sympathetic remodeling makers and serum norepinephrine levels were also significantly increased by circadian disruption. PRV virus-labeled neurons were identified in the superior cervical ganglion (SCG), paraventricular nucleus (PVN), and suprachiasmatic nucleus (SCN) regions. Ganglionic blockade via designer receptors exclusively activated by designer drugs (DREADD) technique suppressed the activity of sympathetic nervous system and significantly alleviated the disruption-related cardiac dysfunction.

Conclusion: Circadian disruption adversely affected cardiac remodeling after MI possibly by activating sympathetic nervous system, and suppressing sympathetic activity can attenuate this disruption-related cardiac dysfunction.

Circadian influence on inflammatory response during cardiovascular disease

Circadian rhythms follow a 24 h day and night cycle, regulate vital physiological processes, and are especially relevant to cardiovascular growth, renewal, repair, and remodeling. A recent flurry of clinical and experimental studies reveals a profound circadian influence on immune responses in cardiovascular disease. The first section of this review summarizes the importance of circadian rhythms for cardiovascular health and disease. The second section introduces the circadian nature of inflammatory responses. The third section combines these to elucidate a new role for the circadian system, influencing inflammation in heart disease, especially myocardial infarction. Particular focus is on circadian regulation of the NACHT, LRR, and PYD domains-containing protein 3 inflammasome, neutrophils, monocytes/macrophages, and T cells involved in cardiac repair. A role for biological sex is noted. The final section explores circadian influences on inflammation in other major cardiovascular conditions. Circadian regulation of inflammation has profound implications for benefitting the diagnosis, treatment, and prognosis of patients with cardiovascular disease.

Circadian influence on the microbiome improves heart failure outcomes

Myocardial infarction (MI) leading to heart failure (HF) is a major cause of death worldwide. Previous studies revealed that the circadian system markedly impacts cardiac repair post-MI, and that light is an important environmental factor modulating the circadian influence over healing. Recent studies suggest that gut physiology also affects the circadian system, but how it contributes to cardiac repair post-MI and in HF is not well understood. To address this question, we first used a murine coronary artery ligation MI model to reveal that an intact gut microbiome is important for cardiac repair. Specifically, gut microbiome disruption impairs normal inflammatory responses in infarcted myocardium, elevates adverse cardiac gene biomarkers, and leads to worse HF outcomes. Conversely, reconstituting the microbiome post-MI in mice with prior gut microbiome disruption improves healing, consistent with the notion that normal gut physiology contributes to cardiac repair. To investigate a role for the circadian system, we initially utilized circadian mutant Clock∆19/∆19 mice, revealing that a functional circadian mechanism is necessary for gut microbiome benefits on post-MI cardiac repair and HF. Finally, we demonstrate that circadian-mediated gut responses that benefit cardiac repair can be conferred by time-restricted feeding, as wake time feeding of MI mice improves HF outcomes, but these benefits are not observed in MI mice fed during their sleep time. In summary, gut physiology is important for cardiac repair, and the circadian system influences the beneficial gut responses to improve post-MI and HF outcomes.

Dim light at night exacerbates stroke outcome

Circadian rhythms are endogenous biological cycles that synchronize physiology and behaviour to promote optimal function. These ~24-hr internal rhythms are set to precisely 24 hr daily by exposure to the sun. However, the prevalence of night-time lighting has the potential to dysregulate these biological functions. Hospital patients may be particularly vulnerable to the consequences of light at night because of their compromised physiological state. A mouse model of stroke (middle cerebral artery occlusion; MCAO) was used to test the hypothesis that exposure to dim light at night impairs responses to a major insult. Stroke lesion size was substantially larger among animals housed in dLAN after reperfusion than animals maintained in dark nights. Mice housed in dLAN for three days after the stroke displayed increased post-stroke anxiety-like behaviour. Overall, dLAN amplified pro-inflammatory pathways in the CNS, which may have exacerbated neuronal damage. Our results suggest that exposure to LAN is detrimental to stroke recovery.

Circadian mutant mice with obesity and metabolic syndrome are resilient to cardiovascular disease

Obesity and metabolic syndrome commonly underlie cardiovascular disease. Clock^Δ19/Δ19 mice fed a normal diet develop obesity and metabolic syndrome; however, it is not known whether they develop or are resilient to cardiovascular disease. We found that Clock^Δ19/Δ19 mice do not develop cardiac dysfunction, despite their underlying conditions. Moreover, in contrast to wild-type controls fed a high-fat diet (HFD), Clock^Δ19/Δ19 HFD mice still do not develop cardiovascular disease. Indeed, Clock^Δ19/Δ19 HFD mice have preserved heart weight despite their obesity, no cardiomyocyte hypertrophy, and preserved heart structure and function, even after 24 wk of a HFD. To determine why Clock^Δ19/Δ19 mice are resilient to cardiac dysfunction despite their underlying obesity and metabolic conditions, we examined global cardiac gene expression profiles by microarray and bioinformatics analyses, revealing that oxidative stress pathways were involved. We examined the pathways in further detail and found that 1) SIRT-dependent oxidative stress pathways were not directly involved in resilience; 2) 4-hydroxynonenal (4-HNE) increased in wild-type HFD but not Clock^Δ19/Δ19 mice, suggesting less reactive oxygen species in Clock^Δ19/Δ19 mice; 3) cardiac catalase (CAT) and glutathione peroxidase (GPx) increased, suggesting strong antioxidant defenses in the hearts of Clock^Δ19/Δ19 mice; and 4) Pparγ was upregulated in the hearts of Clock^Δ19/Δ19 mice; this circadian-regulated gene drives transcription of CAT and GPx, providing a molecular basis for resilience in the Clock^Δ19/Δ19 mice. These findings shed new light on the circadian regulation of oxidative stress and demonstrate an important role for the circadian mechanism in resilience to cardiovascular disease.NEW & NOTEWORTHY We examined whether obesity and metabolic syndrome underlie the development of cardiac dysfunction in circadian mutant Clock^Δ19/Δ19 mice. Surprisingly, we demonstrate that although Clock^Δ19/Δ19 mice develop metabolic dysfunction, they are protected from cardiac hypertrophy, left ventricular remodeling, and diastolic dysfunction, in contrast to wild-type controls, even when challenged with a chronic high-fat diet. These findings shed new light on the circadian regulation of oxidative stress pathways, which can mediate resilience to cardiovascular disease.

Association between circadian disruption and diseases: A narrative review

Circadian rhythms play an important role in a wide range of human physiology and pathology. Individuals increasingly experience situations such as night-shift work schedules, likely leading to circadian disruption. Recent studies have also demonstrated that patients with other diseases often show symptoms of circadian disruption as manifested by the sleep-wake cycle and other biological rhythms. Circadian disruption often results in changes to the phase, period, and amplitude of the sleep-wake cycle, melatonin rhythm, and core body temperature. Several cardiometabolic, psychiatric, and neurodegenerative diseases are closely related to circadian disruption. Several interventions are also available, including phototherapy, exogenous melatonin, and exercise. The cumulative findings suggest that circadian disruption can increase risk for some cardiometabolic diseases. Circadian disruption also acts as a concomitant symptom of several psychiatric and neurodegenerative diseases. More attention should be paid to evaluating the impact of circadian disruption on these related diseases, as well as the benefits of the mitigation interventions for both circadian disruption and related diseases.

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.

Complexities in cardiovascular rhythmicity: perspectives on circadian normality, ageing and disease

Biological rhythms exist in organisms at all levels of complexity, in most organs and at myriad time scales. Our own biological rhythms are driven by energy emitted by the sun, interacting via our retinas with brain stem centres, which then send out complex messages designed to synchronize the behaviour of peripheral non-light sensing organs, to ensure optimal physiological responsiveness and performance of the organism based on the time of day. Peripheral organs themselves have autonomous rhythmic behaviours that can act independently from central nervous system control but is entrainable. Dysregulation of biological rhythms either through environment or disease has far-reaching consequences on health that we are only now beginning to appreciate. In this review, we focus on cardiovascular rhythms in health, with ageing and under disease conditions.

Preoperative circadian physical activity rhythm and postoperative delirium in cardiovascular surgery patients

Postoperative delirium, a common perioperative complication, is frequently observed in elderly surgical patients. Few studies have investigated the life rhythm of preoperative patients, and whether or not the preoperative life rhythm is associated with the development of postoperative delirium. The purpose of this study was to investigate the relationship between the preoperative circadian physical activity rhythm and postoperative delirium in cardiovascular surgery patients. A total of 43 patients who underwent cardiovascular surgery were included in this prospective study between July 2016 and September 2017 at Kobe University Hospital. All subjects used a "Life Microscope" wristband (a wristwatch-type terminal incorporating a 3-axis accelerometer monitoring) for 3-7 days at home before the planned surgery. Hourly mean values were calculated for the metabolic equivalents from the obtained activity amounts, and subsequently evaluated using cosine periodic regression analysis. The circadian rhythm parameters of mesor (24 h time series mean), amplitude (half the peak-trough variation), and acrophase (peak time) for the metabolic equivalents were obtained. The intensive care delirium screening checklist was used to assess for postoperative delirium. The acrophase significantly advanced in the postoperative delirium group (median, 11:55 h [interquartile range, 11:06-12:27 h]) compared to the group without postoperative delirium (median, 13:25 h [interquartile range, 12:52-14:13 h]) (p < .001). Furthermore, binary logistic regression analysis showed that advances in the physical activity phase remained independently associated with postoperative delirium (odds ratio, 0.003 [95% confidence interval, 0-0.63]). These results suggest that misalignment between advanced life rhythm before hospitalization and life rhythm after hospitalization might be associated with risk for developing postoperative delirium. Our results led us to speculate that adequate consideration of the patient's life rhythm before hospitalization is needed to prevent postoperative delirium.

A Tissue-Specific Rhythmic Recruitment Pattern of Leukocyte Subsets

The circulating of leukocytes in the vasculature to reach various organs is a crucial step that allows them to perform their function. With a sequence of interaction with the endothelial cells, the leukocytes emigrate from the circulation either by firm attachment to vascular beds or by trafficking into the tissues. Recent findings reveal that the leukocyte recruitment shows time as well as tissue specificity depending on the cell type and homing location. This spatiotemporal distribution of leukocyte subsets is driven by the circadian expression of pro-migratory molecules expressed on the leukocytes and the endothelium. Both the systemic circadian signals and the cell's intrinsic molecule clock contribute to the oscillatory expression of pro-migratory molecules. The rhythmic recruitment of leukocytes plays an important role in the time-dependency of immune responses. It also helps to update blood components and maintain the tissue circadian microenvironment. In this review, we discuss the current knowledge about the mechanisms of the circadian system regulating the leukocyte rhythmic migration, the recruitment pattern of leukocyte subsets into different tissue/organs, and the time-dependent effects behind this process.

Influence of mental stress and environmental toxins on circadian clocks: Implications for redox regulation of the heart and cardioprotection

Risk factors in the environment such as air pollution and mental stress contribute to the development of chronic non-communicable disease. Air pollution was identified as the leading health risk factor in the physical environment, followed by water pollution, soil pollution/heavy metals/chemicals and occupational exposures, however neglecting the non-chemical environmental health risk factors (e.g. mental stress and noise). Epidemiological data suggest that environmental risk factors are associated with higher risk for cardiovascular, metabolic and mental diseases, including hypertension, heart failure, myocardial infarction, diabetes, arrhythmia, stroke, depression and anxiety disorders. We provide an overview on the impact of the external exposome comprising risk factors/exposures on cardiovascular health with a focus on dysregulation of stress hormones, mitochondrial function, redox balance and inflammation with special emphasis on the circadian clock. Finally, we assess the impact of circadian clock dysregulation on cardiovascular health and the potential of environment-specific preventive strategies or "chrono" therapy for cardioprotection. LINKED ARTICLES: This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.23/issuetoc.

The Role of Bone Morphogenetic Protein 7 (BMP-7) in Inflammation in Heart Diseases

Bone morphogenetic protein-7 is (BMP-7) is a potent anti-inflammatory growth factor belonging to the Transforming Growth Factor Beta (TGF-β) superfamily. It plays an important role in various biological processes, including embryogenesis, hematopoiesis, neurogenesis and skeletal morphogenesis. BMP-7 stimulates the target cells by binding to specific membrane-bound receptor BMPR 2 and transduces signals through mothers against decapentaplegic (Smads) and mitogen activated protein kinase (MAPK) pathways. To date, rhBMP-7 has been used clinically to induce the differentiation of mesenchymal stem cells bordering the bone fracture site into chondrocytes, osteoclasts, the formation of new bone via calcium deposition and to stimulate the repair of bone fracture. However, its use in cardiovascular diseases, such as atherosclerosis, myocardial infarction, and diabetic cardiomyopathy is currently being explored. More importantly, these cardiovascular diseases are associated with inflammation and infiltrated monocytes where BMP-7 has been demonstrated to be a key player in the differentiation of pro-inflammatory monocytes, or M1 macrophages, into anti-inflammatory M2 macrophages, which reduces developed cardiac dysfunction. Therefore, this review focuses on the molecular mechanisms of BMP-7 treatment in cardiovascular disease and its role as an anti-fibrotic, anti-apoptotic and anti-inflammatory growth factor, which emphasizes its potential therapeutic significance in heart diseases.

Circadian rhythms and the molecular clock in cardiovascular biology and disease

The Earth turns on its axis every 24 h; almost all life on the planet has a mechanism - circadian rhythmicity - to anticipate the daily changes caused by this rotation. The molecular clocks that control circadian rhythms are being revealed as important regulators of physiology and disease. In humans, circadian rhythms have been studied extensively in the cardiovascular system. Many cardiovascular functions, such as endothelial function, thrombus formation, blood pressure and heart rate, are now known to be regulated by the circadian clock. Additionally, the onset of acute myocardial infarction, stroke, arrhythmias and other adverse cardiovascular events show circadian rhythmicity. In this Review, we summarize the role of the circadian clock in all major cardiovascular cell types and organs. Second, we discuss the role of circadian rhythms in cardiovascular physiology and disease. Finally, we postulate how circadian rhythms can serve as a therapeutic target by exploiting or altering molecular time to improve existing therapies and develop novel ones.

Chronobiological Influence Over Cardiovascular Function: The Good, the Bad, and the Ugly

Essentially all biological processes fluctuate over the course of the day, observed at cellular (eg, transcription, translation, and signaling), organ (eg, contractility and metabolism), and whole-body (eg, physical activity and appetite) levels. It is, therefore, not surprising that both cardiovascular physiology (eg, heart rate and blood pressure) and pathophysiology (eg, onset of adverse cardiovascular events) oscillate during the 24-hour day. Chronobiological influence over biological processes involves a complex interaction of factors that are extrinsic (eg, neurohumoral factors) and intrinsic (eg, circadian clocks) to cells. Here, we focus on circadian governance of 6 fundamentally important processes: metabolism, signaling, electrophysiology, extracellular matrix, clotting, and inflammation. In each case, we discuss (1) the physiological significance for circadian regulation of these processes (ie, the good); (2) the pathological consequence of circadian governance impairment (ie, the bad); and (3) whether persistence/augmentation of circadian influences contribute to pathogenesis during distinct disease states (ie, the ugly). Finally, the translational impact of chronobiology on cardiovascular disease is highlighted.

SR9009 administered for one day after myocardial ischemia-reperfusion prevents heart failure in mice by targeting the cardiac inflammasome

Reperfusion of patients after myocardial infarction (heart attack) triggers cardiac inflammation that leads to infarct expansion and heart failure (HF). We previously showed that the circadian mechanism is a critical regulator of reperfusion injury. However, whether pharmacological targeting using circadian medicine limits reperfusion injury and protects against HF is unknown. Here, we show that short-term targeting of the circadian driver REV-ERB with SR9009 benefits long-term cardiac repair post-myocardial ischemia reperfusion in mice. Gain and loss of function studies demonstrate specificity of targeting REV-ERB in mice. Treatment for just one day abates the cardiac NLRP3 inflammasome, decreasing immunocyte recruitment, and thereby allowing the vulnerable infarct to heal. Therapy is given in vivo, after reperfusion, and promotes efficient repair. This study presents downregulation of the cardiac inflammasome in fibroblasts as a cellular target of SR9009, inviting more targeted therapeutic investigations in the future.