Chronotherapy of cardiac and vascular disease: timing medications to circadian rhythms to optimize treatment effects and outcomes

Circadian (diurnal/nocturnal) pattern of cardiac arrhythmias

Circadian rhythms follow 24-hour biological cycle patterns controlled by internal biological or circadian clocks that optimize organismal homeostasis according to predictable environmental changes. These clocks are found in virtually all cells in the body, including cardiomyocytes. Triggers for and/or the occurrence of sudden cardiac death (SCD) and cardiac arrhythmias seem to follow such daily patterns. This review highlights data from studies exploring the role of day/night rhythms in the timing of arrhythmic events, studies describing the environmental, behavioral, and circadian mechanisms regulating cardiac electrophysiology focusing on the circadian pattern of arrhythmias and SCD. Mechanisms involved relate to circadian control of electrophysiological properties, vagal tone, and sleep disorders, as well as the potential interaction and synergism among these factors. By studying the diurnal variations of arrhythmias, therapy can be improved by optimally timing it to their circadian pattern and a person's internal body clock time. Potential treatment targets for arrhythmias with nocturnal onset may include upstream therapy for underlying comorbidities, type and timing of drug intake, pulmonary vein isolation, ablation of the ganglionated plexus, and autonomic nervous system control. Thus, specific history-taking, screening, and diagnostic workup are recommended to identify and characterize comorbidities and potential contributors to nocturnal arrhythmias, such as obesity, advanced age, diabetes, hypertension, and heart failure. In this direction, symptoms of sleep apnea may comprise snoring and excessive daytime sleepiness. Risk factors include obesity, decreased upper airway dimensions, and heart failure. Thus, one should have a low threshold for sleep testing to assess for sleep apnea. Sleep apnea treatment decreases ventricular arrhythmias and ameliorates some severe bradycardic episodes, often obviating the need for pacemaker implantation. Importantly, comorbidity treatment and lifestyle optimization remain crucial.

Stroke in the Time of Circadian Medicine

Time-of-day significantly influences the severity and incidence of stroke. Evidence has emerged not only for circadian governance over stroke risk factors, but also for important determinants of clinical outcome. In this review, we provide a comprehensive overview of the interplay between chronobiology and cerebrovascular disease. We discuss circadian regulation of pathophysiological mechanisms underlying stroke onset or tolerance as well as in vascular dementia. This includes cell death mechanisms, metabolism, mitochondrial function, and inflammation/immunity. Furthermore, we present clinical evidence supporting the link between disrupted circadian rhythms and increased susceptibility to stroke and dementia. We propose that circadian regulation of biochemical and physiological pathways in the brain increase susceptibility to damage after stroke in sleep and attenuate treatment effectiveness during the active phase. This review underscores the importance of considering circadian biology for understanding the pathology and treatment choice for stroke and vascular dementia and speculates that considering a patient's chronotype may be an important factor in developing precision treatment following stroke.

Circadian regulation of sinoatrial nodal cell pacemaking function: Dissecting the roles of autonomic control, body temperature, and local circadian rhythmicity

Strong circadian (~24h) rhythms in heart rate (HR) are critical for flexible regulation of cardiac pacemaking function throughout the day. While this circadian flexibility in HR is sustained in diverse conditions, it declines with age, accompanied by reduced maximal HR performance. The intricate regulation of circadian HR involves the orchestration of the autonomic nervous system (ANS), circadian rhythms of body temperature (CRBT), and local circadian rhythmicity (LCR), which has not been fully understood. Here, we developed a mathematical model describing ANS, CRBT, and LCR in sinoatrial nodal cells (SANC) that accurately captures distinct circadian patterns in adult and aged mice. Our model underscores how the alliance among ANS, CRBT, and LCR achieves circadian flexibility to cover a wide range of firing rates in SANC, performance to achieve maximal firing rates, while preserving robustness to generate rhythmic firing patterns irrespective of external conditions. Specifically, while ANS dominates in promoting SANC flexibility and performance, CRBT and LCR act as primary and secondary boosters, respectively, to further enhance SANC flexibility and performance. Disruption of this alliance with age results in impaired SANC flexibility and performance, but not robustness. This unexpected outcome is primarily attributed to the age-related reduction in parasympathetic activities, which maintains SANC robustness while compromising flexibility. Our work sheds light on the critical alliance of ANS, CRBT, and LCR in regulating time-of-day cardiac pacemaking function and dysfunction, offering insights into novel therapeutic targets for the prevention and treatment of cardiac arrhythmias.

The circadian protein BMAL1 supports endothelial cell cycle during angiogenesis

AIMS

The circadian clock is an internal biological timer that co-ordinates physiology and gene expression with the 24-h solar day. Circadian clock perturbations have been associated to vascular dysfunctions in mammals, and a function of the circadian clock in angiogenesis has been suggested. However, the functional role of the circadian clock in endothelial cells (ECs) and in the regulation of angiogenesis is widely unexplored.

METHODS AND RESULTS

Here, we used both in vivo and in vitro approaches to demonstrate that ECs possess an endogenous molecular clock and show robust circadian oscillations of core clock genes. By impairing the EC-specific function of the circadian clock transcriptional activator basic helix-loop-helix ARNT like 1 (BMAL1) in vivo, we detect angiogenesis defects in mouse neonatal vascular tissues, as well as in adult tumour angiogenic settings. We then investigate the function of circadian clock machinery in cultured EC and show evidence that BMAL and circadian locomotor output cycles protein kaput knock-down impair EC cell cycle progression. By using an RNA- and chromatin immunoprecipitation sequencing genome-wide approaches, we identified that BMAL1 binds the promoters of CCNA1 and CDK1 genes and controls their expression in ECs.

CONCLUSION(S)

Our findings show that EC display a robust circadian clock and that BMAL1 regulates EC physiology in both developmental and pathological contexts. Genetic alteration of BMAL1 can affect angiogenesis in vivo and in vitro settings.

Circadian Modulation of the Antioxidant Effect of Grape Consumption: A Randomized Controlled Trial

Grape consumption acts on the immune system to produce antioxidant and anti-inflammatory effects. Since immune activity demonstrates circadian rhythmicity, with peak activity occurring during waking hours, the timing of grape intake may influence the magnitude of its antioxidant effect. This study followed a 2 × 2 factorial randomized, controlled design wherein healthy men and women (n = 32) consumed either a grape or placebo drink with a high-fat meal in the morning or evening. Urine was collected for measurements of biomarkers of oxidative stress and grape metabolites at baseline and post-meal at hour 1 and hours 1-6. F-2 isoprostane levels showed main effects of time period (baseline < hour 1 < hours 1-6, p < 0.0001), time (a.m. > p.m., p = 0.008) and treatment (placebo > grape, p = 0.05). Total F2-isoprostane excretion expressed as % baseline was higher in the a.m. vs. p.m. (p = 0.004) and in the a.m. placebo vs. all other groups (p < 0.05). Tartaric acid and resveratrol excretion levels were higher in the grape vs. placebo group (p < 0.05) but were not correlated with F-2 isoprostane levels. The findings support a protective effect of grape consumption against morning sensitivity to oxidative stress.

Circadian Factors in Stroke: A Clinician's Perspective

Stroke remains one of the leading causes of mortality and long-term and permanent disability worldwide despite technological innovations and developments in pharmacotherapy. In the last few decades, the growing data have evidenced the role of the circadian system in brain vulnerability to damage, the development and evolution of stroke, and short-term and long-term recovery. On the other hand, the stroke itself can affect the circadian system via direct injury of specific brain structures involved in circadian regulation (i.e., hypothalamus, retinohypothalamic tracts, etc.) and impairment of endogenous regulatory mechanisms, metabolic derangement, and a neurogenic inflammatory response in acute stroke. Moreover, the disruption of circadian rhythms can occur or exacerbate as a result of exogenous factors related to hospitalization itself, the conditions in the intensive care unit and the ward (light, noise, etc.), medication (sedatives and hypnotics), and loss of external factors entraining the circadian rhythms. In the acute phase of stroke, patients demonstrate abnormal circadian variations in circadian biomarkers (melatonin, cortisol), core body temperature, and rest-activity patterns. The approaches aimed at the restoration of disrupted circadian patterns include pharmacological (melatonin supplementation) and non-medication (bright light therapy, shifting feeding schedules, etc.) interventions; however, their effects on short- and long-term recovery after stroke are not well understood.

Is obstructive sleep apnea a circadian rhythm disorder?

Obstructive sleep apnea is the most common sleep-related breathing disorder worldwide and remains underdiagnosed. Its multiple associated comorbidities contribute to a decreased quality of life and work performance as well as an increased risk of death. Standard treatment seems to have limited effects on cardiovascular and metabolic aspects of the disease, emphasising the need for early diagnosis and additional therapeutic approaches. Recent evidence suggests that the dysregulation of circadian rhythms, processes with endogenous rhythmicity that are adjusted to the environment through various cues, is involved in the pathogenesis of comorbidities. In patients with obstructive sleep apnea, altered circadian gene expression patterns have been demonstrated. Obstructive respiratory events may promote circadian dysregulation through the effects of sleep disturbance and intermittent hypoxia, with subsequent inflammation and disruption of neural and hormonal homeostasis. In this review, current knowledge on obstructive sleep apnea, circadian rhythm regulation, and circadian rhythm sleep disorders is summarised. Studies that connect obstructive sleep apnea to circadian rhythm abnormalities are critically evaluated. Furthermore, pathogenetic mechanisms that may underlie this association, most notably hypoxia signalling, are presented. A bidirectional relationship between obstructive sleep apnea and circadian rhythm dysregulation is proposed. Approaching obstructive sleep apnea as a circadian rhythm disorder may prove beneficial for the development of new, personalised diagnostic, therapeutic and prognostic tools. However, further studies are needed before the clinical approach to obstructive sleep apnea includes targeting the circadian system.

Recommended timing of medications that impact sleep and wakefulness: A review of the American Prescribers' Digital Reference

An appreciable number of medicines have a recommended unique single time-of-day or asymmetrical or unequal-interval multiple-daily administration schedule. Many prescription and over-the-counter (OTC) products, according to administration time, can exert positive or negative impact on nighttime sleep and daytime wakefulness. Intuitively, medicines used to manage nighttime sleep and daytime wake disorders should be taken, respectively, at night before bedtime and morning after arising. However, some utilized for other medical conditions, if improperly timed, may compromise nocturnal sleep and diurnal attentiveness. We conducted a comprehensive review of the American Prescribers' Digital Reference, internet version of the Physician's Desk Reference, for the recommended scheduling of medications and OTC remedies that can impact sleep and wakefulness. The search revealed several hundred therapies of various classes -- α₂-receptor agonists, antidepressants, barbiturates, central nervous system stimulants, benzodiazepines, dopamine agonists, dopamine norepinephrine reuptake inhibitors, selective norepinephrine reuptake inhibitors, eugeroics, γ-aminobutyric acid modulators, H₁ and H₃-receptor antagonists, melatonin analogues, OTC melatonin-containing products, non-benzodiazepine benzodiazepine-receptor agonists, dual orexin-receptor antagonists, and serotonin modulators -- that have a recommended unique dosing schedule. The tables and text of this article are intended to guide the proper scheduling of these medicines to optimize desired and/or minimize undesired effects.

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.

Insight on Cardiac Chronobiology and Latest Developments of Chronotherapeutic Antihypertensive Interventions for Better Clinical Outcomes

Cardiac circadian rhythms are an important regulator of body functions, including cardiac activities and blood pressure. Disturbance of circadian rhythm is known to trigger and aggravate various cardiovascular diseases. Thus, modulating the circadian rhythm can be used as a therapeutic approach to cardiovascular diseases. Through this work, we intend to discuss the current understanding of cardiac circadian rhythms, in terms of quantifiable parameters like BP and HR. We also elaborate on the molecular regulators and the molecular cascades along with their specific genetic aspects involved in modulating circadian rhythms, with specific reference to cardiovascular health and cardiovascular diseases. Along with this, we also presented the latest pharmacogenomic and metabolomics markers involved in chronobiological control of the cardiovascular system along with their possible utility in cardiovascular disease diagnosis and therapeutics. Finally, we reviewed the current expert opinions on chronotherapeutic approaches for utilizing the conventional as well as the new pharmacological molecules for antihypertensive chronotherapy.

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 rhythms in psoriasis and the potential of chronotherapy in psoriasis management

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

An Overview of the Circadian Clock in the Frame of Chronotherapy: From Bench to Bedside

Most living organisms in both the plant and animal kingdoms have evolved processes to stay in tune with the alternation of day and night, and to optimize their physiology as a function of light supply. In mammals, a circadian clock relying on feedback loops between key transcription factors will thus control the temporally regulated pattern of expression of most genes. Modern ways of life have highly altered the synchronization of human activities with their circadian clocks. This review discusses the links between an altered circadian clock and the rise of pathologies. We then sum up the proofs of concept advocating for the integration of circadian clock considerations in chronotherapy for health care, medicine, and pharmacotherapy. Finally, we discuss the current challenges that circadian biology must face and the tools to address them.

Pharmacogenomics and circadian rhythms as mediators of cardiovascular drug-drug interactions

This article summarizes the current literature and documents new evidence concerning drug-drug interactions (DDI) stemming from pharmacogenomic and circadian rhythm determinants of therapies used to treat common cardiovascular diseases (CVD), such as atherosclerosis and hypertension. Patients with CVD often have more than one pathophysiologic condition, namely metabolic syndromes, hypertension, hyperlipidemia, and hyperglycemia, among others, which necessitate polytherapeutic or polypharmaceutic management. Interactions between drugs, drugs and food/food supplements, or drugs and genetic/epigenetic factors may have adverse impacts on the cardiovascular and other systems of the body. The mechanisms underlying cardiovascular DDI may involve the formation of a complex pharmacointeractome, including the absorption, distribution, metabolism, and elimination of drugs, which affect their respective bioavailability, efficacy, and/or harmful metabolites. The pharmacointeractome of cardiovascular drugs is likely operated with endogenous rhythms controlled by circadian clock genes. Basic and clinical investigations have improved the knowledge and understanding of cardiovascular pharmacogenomics and pharmacointeractomes, and additionally they have presented new evidence that the staging of deterministic circadian rhythms, according to the dosing time of drugs, e.g., upon awakening vs. at bedtime, cannot only differentially impact their pharmacokinetics and pharmacodynamics but also mediate agonistic/synergetic or antagonistic DDI. To properly manage CVD patients and avoid DDI, it is important that clinicians have sufficient knowledge of their multiple risk factors, i.e., age, gender, and life style elements (like diet, smoking, psychological stress, and alcohol consumption), and comorbidities, such as diabetes, hypertension, dyslipidemia, and depression, and the potential interactions between genetic or epigenetic background of their prescribed therapeutics.

Dopamine D1 Receptor-Mediated Regulation of Per1, Per2, CLOCK, and BMAL1 Expression in the Suprachiasmatic Nucleus in Adult Male Rats

Photic and non-photic inputs are reported to affect clock gene expressions and behavioral activities in the SCN. However, it is not known whether dopaminergic input mediates these regulatory effects on clock genes. The present study examined the molecular effects of dopamine D1 agonist on Per1, Per2, CLOCK, and Bmal1 expressions in the SCN and its effect on behavioral activities to determine the role of dopamine D1 receptor in regulation of these gene expressions and behavioral activities in adult male Wistar rats. To examine the molecular effects of dopamine D1 agonist day and night, we injected 20 mg/kg SKF38393 to the first group of rats at 6 a.m. and the second group at 6 p.m. We also injected saline to the third and fourth groups of rats at 6 a.m. and 6 p.m. as control groups. All rats were sacrificed 2 h following the injections. The real-time PCR technique was used to evaluate the clock gene expression. In addition, to examine the effects of dopamine D1 agonists on behavioral activities, we injected 20 mg/kg SKF38393 to SKF receiving group and saline to control group. The behavioral activities of the rats were monitored on the running wheel for 21 days, 1 week following the injections. SKF injections increased the Per2 and CLOCK expressions in the daytime and significantly decreased the Per1 and Bmal1 expressions. However, at night, SKF injections increased only Per2 expressions significantly and decreased the Per1, CLOCK, and Bmal1 genes expressions. Both saline receiving groups showed that all gene expressions were significantly higher except Per2 during nighttime. SKF injection increased the running wheel activity during nighttime significantly. Based on the obtained result, clock gene expression and behavioral activities in adult male Wistar rats may be altered or monitored by administration of exogenous dopamine.

Chronoeffects of the Herbal Medicines Puerariae radix and Coptidis rhizoma in Mice: A Potential Role of REV-ERBα

Identifying drugs with dosing time-dependent effects (chronoeffects) and understanding the underlying mechanisms would help to improve drug treatment outcome. Here, we aimed to determine chronoeffects of the herbal medicines Puerariae radix (PR) and Coptidis rhizoma (CR), and investigate a potential role of REV-ERBα as a drug target in generating chronoeffects. The pharmacological effect of PR on hyperhomocysteinemia in mice was evaluated by measuring total homocysteine, triglyceride levels and lipid accumulation. PR dosed at ZT10 generated a stronger effect on hyperhomocysteinemia than drug dosed at ZT2. Furthermore, PR increased the expression levels of REV-ERBα target genes Bhmt, Cbs and Cth (encoding three key enzymes responsible for homocysteine catabolism), thereby alleviating hyperhomocysteinemia in mice. Moreover, CR attenuated chronic colitis in mice in a dosing time-dependent manner based on measurements of disease activity index, colon length, malondialdehyde/myeloperoxidase activities and IL-1β/IL-6 levels. ZT10 dosing generated a stronger anti-colitis effect as compared to ZT2 dosing. This was accompanied by lower production of colonic inflammatory cytokines (i.e., Nlrp3, IL-1β, IL-6, Tnf-α and Ccl2, REV-ERBα target genes) in colitis mice dosed at ZT10. The diurnal patterns of PR and CR effects were respectively consistent with those of puerarin (a main active constituent of PR, a REV-ERBα antagonist) and berberine (a main active constituent of CR, a REV-ERBα agonist). In addition, loss of Rev-erbα in mice abolished the dosing time-dependency in PR and CR effects. In conclusion, the therapeutic effects of PR and CR depend on dosing time in mice, which are probably attributed to diurnal expression of REV-ERBα as the drug target. Our findings have implications for improving therapeutic outcomes of herbal medicines with a chronotherapeutic approach.

Elevated asleep blood pressure and non-dipper 24h patterning best predict risk for heart failure that can be averted by bedtime hypertension chronotherapy: A review of the published literature

Several prospective studies consistently report elevated asleep blood pressure (BP) and blunted sleep-time relative systolic BP (SBP) decline (non-dipping) are jointly the most significant prognostic markers of cardiovascular disease (CVD) risk, including heart failure (HF); therefore, they, rather than office BP measurements (OBPM) and ambulatory awake and 24 h BP means, seemingly are the most worthy therapeutic targets for prevention. Published studies of the 24 h BP pattern in HF are sparse in number and of limited sample size. They report high prevalence of the abnormal non-dipper/riser 24 h SBP patterning. Despite the established clinical relevance of the asleep BP, past as do present hypertension guidelines recommend the diagnosis of hypertension rely on OBPM and, when around-the-clock ambulatory BP monitoring (ABPM) is conducted to confirm the elevated OBPM, either on the derived 24 h or "daytime" BP means. Additionally, hypertension guidelines do not advise the time-of-day when BP-lowering medications should be ingested, in spite of known ingestion-time differences in their pharmacokinetics and pharmacodynamics. Between 1976 and 2020, 155 unique trials of ingestion-time differences in the effects of 37 different single and 14 dual-combination hypertension medications, collectively involving 23,972 patients, were published. The vast majority (83.9%) of them found the at-bedtime/evening in comparison to upon-waking/morning treatment schedule resulted in more greatly enhanced: (i) reduction of asleep BP mean without induced sleep-time hypotension; (ii) reduction of the prevalence of the higher CVD risk non-dipper/riser 24 h BP phenotypes; (iii) improvement of kidney function, reduction of cardiac pathology, and with lower incidence of adverse effects. Most notably, no single published randomized trial found significantly better BP-lowering, particularly during sleep, or medical benefits of the most popular upon-waking/morning hypertension treatment-time scheme. Additionally, prospective outcome trials have substantiated that the bedtime relative to the upon-waking, ingestion of BP-lowering medications not only significantly reduces risk of HF but also improves overall CVD event-free survival time.

Sleep and Cardiovascular Risk

Sleep is essential for healthy being and healthy functioning of human body as a whole, as well as each organ and system. Sleep disorders, such as sleep-disordered breathing, insomnia, sleep fragmentation, and sleep deprivation are associated with the deterioration in human body functioning and increased cardiovascular risks. However, owing to the complex regulation and heterogeneous state sleep per se can be associated with cardiovascular dysfunction in susceptible subjects. The understanding of sleep as a multidimensional concept is important for better prevention and treatment of cardiovascular diseases.

Clock-Modulating Activities of the Anti-Arrhythmic Drug Moricizine

Dysregulated circadian functions contribute to various diseases, including cardiovascular disease. Much progress has been made on chronotherapeutic applications of drugs against cardiovascular disease (CVD); however, the direct effects of various medications on the circadian system are not well characterized. We previously conducted high-throughput chemical screening for clock modulators and identified an off-patent anti-arrhythmic drug, moricizine, as a clock-period lengthening compound. In Per2:LucSV reporter fibroblast cells, we showed that under both dexamethasone and forskolin synchronization, moricizine was able to increase the circadian period length, with greater effects seen with the former. Titration studies revealed a dose-dependent effect of moricizine to lengthen the period. In contrast, flecainide, another Class I anti-arrhythmic, showed no effects on circadian reporter rhythms. Real-time qPCR analysis in fibroblast cells treated with moricizine revealed significant circadian time- and/or treatment-dependent expression changes in core clock genes, consistent with the above period-lengthening effects. Several clock-controlled cardiac channel genes also displayed altered expression patterns. Using tissue explant culture, we showed that moricizine was able to significantly prolong the period length of circadian reporter rhythms in atrial ex vivo cultures. Using wild-type C57BL/6J mice, moricizine treatment was found to promote sleep, alter circadian gene expression in the heart, and show a slight trend of increasing free-running periods. Together, these observations demonstrate novel clock-modulating activities of moricizine, particularly the period-lengthening effects on cellular oscillators, which may have clinical relevance against heart diseases.

Systematic review and quality evaluation of published human ingestion-time trials of blood pressure-lowering medications and their combinations

The pharmacokinetics (PK) - absorption, distribution, metabolism, and elimination - and pharmacodynamics (PD) of hypertension medications can be significantly affected by circadian rhythms. As a consequence, the time when blood pressure (BP) lowering medications are ingested, with reference to the staging of all involved circadian rhythms modulating PK and PD, can affect their duration of action, magnitude of effect on features of the 24 h BP profile, and safety. We conducted a systematic and comprehensive review of published prospective human trials that investigated individual hypertension medications of all classes and their combinations for ingestion-time differences in BP-lowering, safety, patient adherence, and markers of hypertension-associated target organ pathology of the kidney and heart. The systematic review yielded 155 trials published between 1976 and 2020 - totaling 23,972 hypertensive individuals - that evaluated 37 different single and 14 dual-combination therapies. The vast (83.9%) majority of them reported clinically and statistically significant benefits - including enhanced reduction of asleep BP mean without induced sleep-time hypotension, reduced prevalence of the higher cardiovascular risk non-dipper 24 h BP profile, decreased incidence of adverse effects, improved kidney function, and reduced cardiac pathology - when hypertension medications are ingested at-bedtime/evening rather than upon-waking/morning. Nonetheless, the findings and conclusions of some past conducted trials are inconsistent, often due to disparities and deficiencies of the investigative protocols. Accordingly, we developed a quality assessment method based upon the eight items identified as crucial according to the recently published guidelines of the International Society for Chronobiology and the American Association for Medical Chronobiology and Chronotherapeutics for the design and conduct of human clinical trials on ingestion-time differences of hypertension medications. Among the most frequent deficiencies are: absence or miscalculation of minimum required sample size (83.2%), incorrect choice of primary BP endpoint (53.6%), and inappropriate arbitrary and unrepresentative clock hours chosen for tested treatment times (53.6%). The inability of the very small proportion (16.1%) of trials to verify the advantages of the at-bedtime/evening treatment strategy is likely explained by deficiencies of their study design and conduct. Nonetheless, regardless of the quality score of the 155 trials retrieved by our systematic review, it is most noteworthy that no single published prospective randomized trial reported significantly enhanced BP-lowering, safety, compliance, or other benefits of the unjustified by medical evidence, yet still most recommended, upon-waking/morning hypertension treatment-time scheme.

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.