Circadian rhythms in adaptive immunity

Circadian rhythm disruption aggravates alveolar bone loss in rat apical periodontitis

BACKGROUND

Circadian rhythm disruption (CRD) affects the expression levels of a range of biological clock genes, such as brain and muscle ARNT-Like-1 (BMAL1), which is considered to be an important factor in triggering or exacerbating inflammatory response. However, the underlying effect of CRD on the pathogenesis of apical periodontitis, a common oral inflammatory disease, currently remains unknown. Exploring the effects and pathogenic mechanisms of CRD on apical periodontitis will be beneficial in providing new ideas for the prevention and treatment of apical periodontitis.

METHODOLOGY

The cross-sectional study was conducted among patients with apical periodontitis visiting to hospital. Rat models combining CRD and apical periodontitis were constructed, and the destruction of periapical alveolar bone was assessed by Micro-CT, H&E, and TRAP staining assay. Rat periapical alveolar bone tissues were collected for RT-qPCR and immunohistochemistry to further detect the expression of periapical biological clock genes. A model of apical periodontitis was constructed using Bmal1-/- and WT rats to further verify the key role played by Bmal1. Finally, rats raised in CRD environment were intraperitoneally injected with melatonin to restore the circadian rhythm, and the periapical alveolar bone repair was observed by Masson's staining and staining of osteogenic markers (ALP, RUNX2).

RESULTS

A close association between CRD and acute exacerbation of chronic apical periodontitis (CAP) in patients was first found in an epidemiological survey. By constructing animal models of CRD and apical periodontitis, it was found that CRD could aggravate the inflammatory stress of apical periodontitis and even drive the acute exacerbation of CAP. Further investigations suggested that the expression of crucial clock genes, especially Bmal1, were significantly disrupted in the periapical tissue of apical periodontitis. In addition, the periapical tissue from Bmal1 knockout rat displayed stronger inflammatory response and more severe alveolar bone destruction in apical periodontitis. Restoring circadian rhythm by melatonin supplementation could effectively alleviate both the inflammatory response and alveolar bone loss in apical periodontitis.

CONCLUSION

CRD is a novel trigger in aggravating the inflammatory response and alveolar bone loss of apical periodontitis. Melatonin is expected to be used in the dental clinic as an important adjunctive therapy strategy for the healing of periapical tissue in apical periodontitis.

Chrono-optimizing vaccine administration: a systematic review and meta-analysis

Background

Increasing evidence suggests that vaccine responses may vary based on the time of day of administration. This systematic review provides a comprehensive overview of the impact of vaccination timing on immune responses, to assess its potential role in optimizing vaccination programs.

Methods

A systematic literature search was performed in Embase, Medline and Scopus to identify eligible observational studies and clinical trials that assessed immune responses following vaccination at different times of the day in humans. A meta-analysis of clinical trials was conducted to quantify the effect size of vaccination timing on antibody responses.

Results

The search identified 17 studies that compared vaccine responses at different times of the day, covering vaccinations against COVID-19 (9), influenza (5), hepatitis B (2), hepatitis A (1), and pneumococcal infection (1). Eleven out of these 17 studies demonstrated statistically significant effects of vaccination timing on the antibody response, with 10 reporting stronger antibody responses following morning compared to afternoon vaccination. Of the six subgroups with an average age of 60 years and older, five showed significantly stronger antibody responses following morning vaccination, while the sixth showed a significant effect only in men. In contrast, only five out of 16 subgroups with an average age younger than 60 years showed a statistically significant effect of vaccination timing on antibody titers. Similarly, the meta-analysis indicated that receiving influenza vaccination in the morning elicited a stronger antibody response than in the afternoon (SMD = 0.24, 95% CI = 0.01-0.47), with subgroup analyses revealing a larger effect in adults aged 65 and older (SMD = 0.32, 95% CI = 0.21-0.43) compared to those aged 60 or younger (SMD = 0.00, 95% CI = -0.17-0.17).

Conclusion

Morning vaccination enhanced antibody responses in adults aged 60 years and older, a key demographic for influenza and COVID-19 vaccination. Chrono-optimizing vaccine administration may offer a low-risk, low-cost strategy to boost vaccine effectiveness in this age group.

Systematic review registration

https://inplasy.com/inplasy-2025-1-0060/.

How Effective Are the Canine Visceral Leishmaniasis Vaccines Currently Being Tested in Dogs? A Systematic Review and Meta-Analysis

Canine visceral leishmaniasis (CVL) is a zoonotic disease of great worldwide importance and can be prevented by vaccinating seronegative dogs. The objective of the present systematic review and meta-analysis is to verify the efficacy rate of vaccines tested in dogs against CVL or L. infantum infection. We used PRISMA guidelines for this review and Pubmed, Web of Science, Scopus, Cochrane, Scielo and CABI to find studies about vaccines against CVL in dogs. Articles were analysed and grouped according to the antigens used. The risk of bias analysis was performed using SYRCLE's RoB tool and meta-analysis using R Statistical language. The final analysis was conducted using 22 studies that assessed DNA, excreted/secreted proteins and subunit vaccines, involving a total of 92 animals, 96 animals and 78 animals, respectively. Regarding DNA vaccines, the analyses revealed non-significant results in terms of preventing parasite presence in the organs or the onset of clinical signs. However, subunit vaccines demonstrated statistically significant results concerning parasite presence in the organs, but not when it comes to clinical signs. Additionally, there was no statistically significant difference observed in parasite burden in the organs or clinical signs for the excreted/secreted vaccines. The meta-analysis indicated that subunit and excreted/secreted protein vaccines were significantly more effective in preventing parasites in vaccinated animals compared to both DNA-based vaccines and control groups. Heterogeneity among studies is a limitation, emphasising the need for standardised protocols for reliable comparisons.

Complex gene-dependent and-independent mechanisms control daily rhythms of hematopoietic cells

The abundance and behaviour of all hematopoietic components display daily oscillations, supporting the involvement of circadian clock mechanisms. The daily variations of immune cell functions, such as trafficking between blood and tissues, differentiation, proliferation, and effector capabilities are regulated by complex intrinsic (cell-based) and extrinsic (neuro-hormonal, organism-based) mechanisms. While the role of the transcriptional/translational molecular machinery, driven by a set of well-conserved genes (Clock genes), in nucleated immune cells is increasingly recognized and understood, the presence of non-transcriptional mechanisms remains almost entirely unexplored. Studies on anucleate hematopoietic components, such as red blood cells and platelets, have shown that auto-sustained redox reaction cycles persist and operate in mammals. This opens to the possibility that transcriptional and non-transcriptional circadian mechanisms might coexist in nucleated immune cell populations, potentially complementing each other. It is becoming increasingly clear that disruption of the circadian rhythm at the central level (core clock) is strongly implicated in a plethora of diseases that are associated with maladaptive immune responses. On the other hand, several evidence imply that dysregulated immune activity (e.g. excessive inflammation) may alter/disrupt the proper functioning of peripheral clocks. This knowledge paves the way to the exploitation of chronobiological concepts in clinical practice. A better comprehension of various transcriptional/translational and biochemical mechanisms that maintain rhythmicity in immune system activities, as well as the many factors (host-derived, microbiota-derived, environment) that can alter or disrupt these processes, will facilitate the development of novel chrono-immunotherapeutic approaches.

Chronic CRYPTOCHROME deficiency enhances cell-intrinsic antiviral defences

The within-host environment changes over circadian time and influences the replication and severity of viruses. Genetic knockout of the circadian transcription factors CRYPTOCHROME 1 and CRYPTOCHROME 2 (CRY1-/-/CRY2-/-; CKO) leads to altered protein homeostasis and chronic activation of the integrated stress response (ISR). The adaptive ISR signalling pathways help restore cellular homeostasis by downregulating protein synthesis in response to endoplasmic reticulum overloading or viral infections. By quantitative mass spectrometry analysis, we reveal that many viral recognition proteins and type I interferon (IFN) effectors are significantly upregulated in lung fibroblast cells from CKO mice compared with wild-type (WT) mice. This basal 'antiviral state' restricts the growth of influenza A virus and is governed by the interaction between proteotoxic stress response pathways and constitutive type I IFN signalling. CKO proteome composition and type I IFN signature were partially phenocopied upon sustained depletion of CRYPTOCHROME (CRY) proteins using a small-molecule CRY degrader, with modest differential gene expression consistent with differences seen between CKO and WT cells. Our results highlight the crosstalk between circadian rhythms, cell-intrinsic antiviral defences and protein homeostasis, providing a tractable molecular model to investigate the interface of these key contributors to human health and disease.This article is part of the Theo Murphy meeting issue 'Circadian rhythms in infection and immunity'.

Time to start taking time seriously: how to investigate unexpected biological rhythms within infectious disease research

The discovery of rhythmicity in host and pathogen activities dates back to the Hippocratic era, but the causes and consequences of these biological rhythms have remained poorly understood. Rhythms in infection phenotypes or traits are observed across taxonomically diverse hosts and pathogens, suggesting general evolutionary principles. Understanding these principles may enable rhythms to be leveraged in manners that improve drug and vaccine efficacy or disrupt pathogen timekeeping to reduce virulence and transmission. Explaining and exploiting rhythms in infections require an integrative and multidisciplinary approach, which is a hallmark of research within chronobiology. Many researchers are welcomed into chronobiology from other fields after observing an unexpected rhythm or time-of-day effect in their data. Such findings can launch a rich new research topic, but engaging with the concepts, approaches and dogma in a new discipline can be daunting. Fortunately, chronobiology has well-developed frameworks for interrogating rhythms that can be readily applied in novel contexts. Here, we provide a 'how to' guide for exploring unexpected daily rhythms in infectious disease research. We outline how to establish: whether the rhythm is circadian, to what extent the host and pathogen are responsible, the relevance for host-pathogen interactions, and how to explore therapeutic potential.This article is part of the Theo Murphy meeting issue 'Circadian rhythms in infection and immunity'.

Immune checkpoint inhibitor infusion times and clinical outcomes in patients with melanoma

BACKGROUND

Circadian rhythms impact immune function; a previous study demonstrated that immunotherapy treatment times taking place later in the day correlated with poorer outcomes in patients with melanoma. However, this finding has not been replicated, and other infusion timing schemas are unexplored. The objective of this retrospective, cohort study was to determine if the time of immunotherapy infusion affects outcomes.

MATERIALS AND METHODS

Five hundred and sixteen participants age ≥18 years diagnosed with cutaneous, acral, mucosal, or unknown primary melanoma treated with >1 infusion of nivolumab, pembrolizumab, or combination ipilimumab/PD-1 inhibitors were included. Response rate, toxicity rate, overall survival (OS), and progression-free survival (PFS) were determined based on infusion timing.

RESULTS

Patients with ≥1 late infusion (after 4 pm) among their first 4 infusions had slightly poorer objective response rate compared with only pre-4 pm infusions (39.7% vs 44.5%), but no significant associations with late infusions and PFS and OS (P = .23, .93, respectively). Multivariable analyses showed no statistically significant association with outcomes for patients with any post-4 pm infusion among the first 4; median infusion time was also not associated with outcomes. However, considering all infusion times, we found inferior PFS (median 10.6 vs 38.9 months, P < .0001), and numerically inferior OS (median 54.6 vs 81.2 months, P = .19) in patients with ≥20% late infusions. Multivariable models had similarly inferior response and PFS for patients with ≥20% late infusions, and later median infusion times were associated with inferior response, PFS, and OS.

CONCLUSIONS

Late immunotherapy infusion times were associated with inferior outcomes when considering all infusions, but not when considering initial (first 4) infusions.

The role of circadian rhythm regulator PERs in oxidative stress, immunity, and cancer development

The complex interaction between circadian rhythms and physiological functions is essential for maintaining human health. At the heart of this interaction lies the PERIOD proteins (PERs), pivotal to the circadian clock, influencing the timing of physiological and behavioral processes and impacting oxidative stress, immune functionality, and tumorigenesis. PER1 orchestrates the cooperation of the enzyme GPX1, modulating mitochondrial dynamics in sync with daily rhythms and oxidative stress, thus regulating the mechanisms managing energy substrates. PERs in innate immune cells modulate the temporal patterns of NF-κB and TNF-α activities, as well as the response to LPS-induced toxic shock, initiating inflammatory responses that escalate into chronic inflammatory conditions. Crucially, PERs modulate cancer cell behaviors including proliferation, apoptosis, and migration by influencing the levels of cell cycle proteins and stimulating the expression of oncogenes c-Myc and MDM2. PER2/3, as antagonists in cancer stem cell biology, play important roles in differentiating cancer stem cells and in maintaining their stemness. Importantly, the expression of Pers serve as a significant factor for early cancer diagnosis and prognosis. This review delves into the link between circadian rhythm regulator PERs, disruptions in circadian rhythm, and oncogenesis. We examine the evidence that highlights how dysfunctions in PERs activities initiate cancer development, aid tumor growth, and modify cancer cell metabolism through pathways involved in oxidative stress and immune system. Comprehending these connections opens new pathways for the development of circadian rhythm-based therapeutic strategies, with the aims of boosting immune responses and enhancing cancer treatments.

Seasonal variation in sunlight exposure is differently associated with changes in T regulatory and T-helper 17 cell blood counts in adolescent and adults females: a pilot study

Higher prevalence of multiple sclerosis at higher latitudes is associated with reduced sunlight during childhood. Alterations in inflammatory Th17 and regulatory T cells (Treg) are associated with autoimmunity. In Hobart, Australia (latitude 42.8° south), thirteen girls (aged 12-13) and sixteen women had blood collected in the evening in daylight in February/March, (post 15 h daylight) and at the same time in the dark in August/September (post 9 h daylight). Height and weight were measured. Participants completed online surveys prior around menstruation, sleep, exercise and time outside. Proportions of Th17 (CD4 + , CXCR3-, CCR4 + , CCR6 + , CD161 +), total Treg (CD4 + , CD25 + , CD127low), naïve Treg (CD45RA + , CD4 + , CD25 + , CD127low) and memory Treg (CD45RA low, CD4 + , CD25 + , CD127low) were enumerated by flow cytometry (Cytek Aurora). Hours spent outside was greater in summer than winter (12.5 v 10.5, p = 0.0003). The %Treg/CD4 + was higher in summer than winter (7.3% vs 7%, p = 0.004) including memory Treg (3.1% vs 2.9%, p = 0.02) for all females (n = 29), and naïve Treg were 13% higher in summer in women (3.2% vs 2.8%, p = 0.0009), whereas %Th17 remained unchanged. In women, a negative correlation between the number of hours spent outside in summer and %Th17 was observed (r = - 0.53, p = 0.035). The %Th17 cells were higher in women than girls (4.9% vs 3.1%, p = 0.001), whereas girls had a higher total %Treg (7.6% vs 6.7%, p = 0.005), consisting of a higher naïve Treg (5.5% vs 3.7%, p = 0.0001) while the women had a higher %memory Treg (3.4% vs 2.6%, p = 0.0001). These light-dependent seasonal differences may influence immune development in adolescents.

Effect of immune checkpoint inhibitor time-of-day infusion on survival in advanced biliary tract cancer: a propensity score-matched analysis

BACKGROUND

Circadian rhythms in the immune system and anti-tumor responses are underexplored in cancer immunotherapy. Despite the success of immune checkpoint inhibitors (ICIs) in treating advanced biliary tract cancers (BTCs), not all patients benefit. This study examined whether the timing of ICI administration affects outcomes in advanced BTC patients.

METHODS

We included advanced BTC patients from West China Hospital of Sichuan University who received ≥2 ICI treatments from October 2019 to September 2023, with follow-up until May 2024. Primary outcome was overall survival (OS), with secondary outcomes including progression-free survival (PFS), objective response rate (ORR), and adverse events (AEs). Propensity score matching (1:2 ratio, caliper width 0.1) mitigated confounding factors. Cox proportional hazards regression analyzed the impact of ICI timing (post-16:30) on OS and PFS. Chi-square test assessed ORR and AE differences.

RESULTS

Among 221 patients, 51 received ≥20% of ICIs after 16:30; 170 received <20%. Post-matching, 49 late-infusion patients had significantly shorter OS (median 10.1 vs. 14.5 months, HR=1.80, P=0.012) compared to 90 early-infusion patients. Pre-matching, late-infusion patients also had shorter OS (median 9.8 vs. 13.7 months, HR=1.68, P=0.010) and PFS (median 4.9 vs. 8.1 months, HR=1.62, P=0.006). Multivariate analysis confirmed these results. No significant differences were found in ORR (χ^2 = 1.53, P=0.215) or AEs (all P>0.050). Sensitivity analyses supported these findings.

CONCLUSION

Timing of ICI administration affects efficacy in advanced BTC, with pre-16:30 infusions linked to better survival. Larger, prospective studies are needed to validate these results.

Severe acute respiratory syndrome coronavirus 2-reactive salivary antibody detection in South Carolina emergency healthcare workers, September 2019-March 2020

On 19 January 2020, the first case of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was identified in the United States, with the first cases in South Carolina confirmed on 06 March 2020. Due to initial limited testing capabilities and potential for asymptomatic transmission, it is possible that SARS-CoV-2 may have been present earlier than previously thought, while the immune status of at-risk populations was unknown. Saliva from 55 South Carolina emergency healthcare workers (EHCWs) was collected from September 2019 to March 2020, pre- and post-healthcare shifts, and stored frozen. To determine the presence of SARS-CoV-2-reactive antibodies, saliva-acquired post-shift was analysed by enzyme-linked immunosorbent assay (ELISA) with a repeat of positive or inconclusive results and follow-up testing of pre-shift samples. Two participants were positive for SARS-CoV-2 N/S1-reactive IgG, confirmed by follow-up testing, with S1 receptor binding domain (RBD)-specific IgG present in one individual. Positive samples were collected from medical students working in emergency medical services (EMSs) in October or November 2019. The presence of detectable anti-SARS-CoV-2 antibodies in 2019 suggests that immune responses to the virus existed in South Carolina, and the United States, in a small percentage of EHCWs prior to the earliest documented coronavirus disease 2019 (COVID-19) cases. These findings suggest the feasibility of saliva as a noninvasive tool for surveillance of emerging outbreaks, and EHCWs represent a high-risk population that should be the focus of infectious disease surveillance.

Biological Clock Perspective in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by systemic polyarticular pain, and its main pathological features include inflammatory cell infiltration, synovial fibroblast proliferation, and cartilage erosion. Immune cells, synovial cells and neuroendocrine factors play pivotal roles in the pathophysiological mechanism underlying rheumatoid arthritis. Biological clock genes regulate immune cell functions, which is linked to rhythmic changes in arthritis pathology. Additionally, the interaction between biological clock genes and neuroendocrine factors is also involved in rhythmic changes in rheumatoid arthritis. This review provides an overview of the contributions of circadian rhythm genes to RA pathology, including their interaction with the immune system and their involvement in regulating the secretion and function of neuroendocrine factors. A molecular understanding of the role of the circadian rhythm in RA may offer insights for effective disease management.

Mathematical modeling of viral infection and the immune response controlled by the circadian clock

Time of day affects how well the immune system responds to viral or bacterial infections. While it is well known that the immune system is regulated by the circadian clock, the dynamic origin of time-of-day-dependent immunity remains unclear. In this paper, we studied the circadian control of immune response upon infection of influenza A virus through mathematical modeling. Dynamic simulation analyses revealed that the time-of-day-dependent immunity was rooted in the relative phase between the circadian clock and the pulse of viral infection. The relative phase, which depends on the time the infection occurs, plays a crucial role in the immune response. It can drive the immune system to one of two distinct bistable states, a high inflammatory state with a higher mortality rate or a safe state characterized by low inflammation. The mechanism we found here also explained why the same species infected by different viruses has different time-of-day-dependent immunities. Further, the time-of-day-dependent immunity was found to be abolished when the immune system was regulated by an impaired circadian clock with decreased oscillation amplitude or without oscillations.

Modulation of the Circadian Rhythm and Oxidative Stress as Molecular Targets to Improve Vascular Dementia: A Pharmacological Perspective

The circadian rhythms generated by the master biological clock located in the brain's hypothalamus influence central physiological processes. At the molecular level, a core set of clock genes interact to form transcription-translation feedback loops that provide the molecular basis of the circadian rhythm. In animal models of disease, a desynchronization of clock genes in peripheral tissues with the central master clock has been detected. Interestingly, patients with vascular dementia have sleep disorders and irregular sleep patterns. These alterations in circadian rhythms impact hormonal levels, cardiovascular health (including blood pressure regulation and blood vessel function), and the pattern of expression and activity of antioxidant enzymes. Additionally, oxidative stress in vascular dementia can arise from ischemia-reperfusion injury, amyloid-beta production, the abnormal phosphorylation of tau protein, and alterations in neurotransmitters, among others. Several signaling pathways are involved in the pathogenesis of vascular dementia. While the precise mechanisms linking circadian rhythms and vascular dementia are still being studied, there is evidence to suggest that maintaining healthy sleep patterns and supporting proper circadian rhythm function may be important for reducing the risk of vascular dementia. Here, we reviewed the main mechanisms of action of molecular targets related to the circadian cycle and oxidative stress in vascular dementia.

Exacerbating effects of circadian rhythm disruption on the systemic lupus erythematosus

OBJECTIVE

Circadian rhythm disruption (CRD) has been associated with inflammation and immune disorders, but its role in SLE progression is unclear. We aimed to investigate the impact of circadian rhythms on immune function and inflammation and their contribution to SLE progression to lupus nephritis (LN).

METHODS

This study retrospectively analysed the clinical characteristics and transcriptional profiles of 373 samples using bioinformatics and machine-learning methods. A flare risk score (FRS) was established to predict overall disease progression for patients with lupus. Mendelian randomisation was used to analyse the causal relationship between CRD and SLE progression.

RESULTS

Abnormalities in the circadian pathway were detected in patients with SLE, and lower enrichment levels suggested a disease state (normalised enrichment score=0.6714, p=0.0062). The disruption of circadian rhythms was found to be closely linked to lupus flares, with the FRS showing a strong ability to predict disease progression (area under the curve (AUC) of 5-year prediction: 0.76). The accuracy of disease prediction was improved by using a prognostic nomogram based on FRS (AUC=0.77). Additionally, Mendelian randomisation analysis revealed an inverse causal relationship between CRD and SLE (OR 0.6284 (95% CI 0.3630 to 1.0881), p=0.0485) and a positive causal relationship with glomerular disorders (OR 0.0337 (95% CI 1.634e-3 to 6.934e-1), p=0.0280).

CONCLUSION

Our study reveals that genetic characteristics arising from CRD can serve as biomarkers for predicting the exacerbation of SLE. This highlights the crucial impact of CRD on the progression of lupus.

Immunotherapy time of infusion impacts survival in head and neck cancer: A propensity score matched analysis

The adaptive immune response is physiologically regulated by the circadian rhythm. Data in lung and melanoma malignancies suggests immunotherapy infusions earlier in the day may be associated with improved response; however, the optimal time of administration for patients with head and neck squamous cell carcinoma (HNSCC) is not known. We aimed to evaluate the association of immunotherapy infusion time with overall survival (OS) and progression free survival (PFS) in patients with HNSCC in an Institutional Review Board-approved, retrospective cohort study. 113 patients met study inclusion criteria and 98 patients were included in a propensity score-matched cohort. In the full unmatched cohort (N = 113), each additional 20 % of infusions received after 1500 h conferred an OS hazard ratio (HR) of 1.35 (95 % C.I.1.2-1.6; p-value = 0.0003) and a PFS HR of 1.34 (95 % C.I.1.2-1.6; p-value < 0.0001). A propensity score-matched analysis of patients who did or did not receive ≥20 % of infusions after 1500 h showed that those who were administered ≥20 % of infusions after 1500 h trended towards a shorter OS (HR = 1.35; p-value = 0.26) and a shorter PFS (HR = 1.57, 95 % C.I. 1.02-2.42, p-value = 0.04). Each additional 20 % of infusions received after 1500 h remained robust in the matched cohort multivariable analysis and was associated with shorter OS (adjusted HR = 1.4 (95 % C.I.1.2-1.8), p-value < 0.001). Patients with advanced HNSCC who received more of their infusions in the afternoon were associated with shorter OS and PFS and scheduling immunotherapy infusions earlier in the day may be warranted.

Effect of immunotherapy-infusion time of day on survival of patients with advanced cancers: a study-level meta-analysis

BACKGROUND

Immune checkpoint inhibitors (ICIs) have become the standard of care for numerous malignancies. Emerging evidence suggests that the time of day (ToD) of ICI administration could impact the outcomes of patients with cancer. The consistency of ToD effects on ICI efficacy awaits initial evaluation.

MATERIALS AND METHODS

This meta-analysis integrates progression-free survival (PFS) and overall survival (OS) data from studies with a defined 'cut-off' ToD. Hazard ratios (HRs) [95% confidence interval (CI)] of an earlier progression or death according to 'early' or 'late' ToD of ICIs were collected from each report and pooled.

RESULTS

Thirteen studies involved 1663 patients (Eastern Cooperative Oncology Group performance status 0-1, 83%; males/females, 67%/33%) with non-small-cell lung cancer (47%), renal cell carcinoma (24%), melanoma (20%), urothelial cancer (5%), or esophageal carcinoma (4%). Most patients received anti-programmed cell death protein 1 or anti-programmed death-ligand 1 (98%), and a small proportion also received anti-cytotoxic T-lymphocyte-associated protein 4 (anti-CTLA-4) (18%). ToD cut-offs were 13:00 or 14:00 (i.e. ICI median infusion time), for six studies, and 16:00 or 16:30 (i.e. reported threshold for weaker vaccination responses) for seven studies. Pooled analyses revealed that the early ToD groups had longer OS (HR 0.50, 95% CI 0.42-0.58; P < 0.00001) and PFS (HR 0.51, 95% CI 0.42-0.61; P < 0.00001) compared with the late ToD groups.

CONCLUSIONS

Patients with selected metastatic cancers seemed to largely benefit from early ToD ICI infusions, which is consistent with circadian mechanisms in immune-cell functions and trafficking. Prospective randomized trials are needed to establish recommendations for optimal circadian timing of ICI-based cancer therapies.

Circadian Regulation of Drug Responses: Toward Sex-Specific and Personalized Chronotherapy

Today's challenge for precision medicine involves the integration of the impact of molecular clocks on drug pharmacokinetics, toxicity, and efficacy toward personalized chronotherapy. Meaningful improvements of tolerability and/or efficacy of medications through proper administration timing have been confirmed over the past decade for immunotherapy and chemotherapy against cancer, as well as for commonly used pharmacological agents in cardiovascular, metabolic, inflammatory, and neurological conditions. Experimental and human studies have recently revealed sexually dimorphic circadian drug responses. Dedicated randomized clinical trials should now aim to issue personalized circadian timing recommendations for daily medical practice, integrating innovative technologies for remote longitudinal monitoring of circadian metrics, statistical prediction of molecular clock function from single-timepoint biopsies, and multiscale biorhythmic mathematical modelling. Importantly, chronofit patients with a robust circadian function, who would benefit most from personalized chronotherapy, need to be identified. Conversely, nonchronofit patients could benefit from the emerging pharmacological class of chronobiotics targeting the circadian clock.

Targeting the blood-brain barrier to delay aging-accompanied neurological diseases by modulating gut microbiota, circadian rhythms, and their interplays

The blood-brain barrier (BBB) impairment plays a crucial role in the pathological processes of aging-accompanied neurological diseases (AAND). Meanwhile, circadian rhythms disruption and gut microbiota dysbiosis are associated with increased morbidity of neurological diseases in the accelerated aging population. Importantly, circadian rhythms disruption and gut microbiota dysbiosis are also known to induce the generation of toxic metabolites and pro-inflammatory cytokines, resulting in disruption of BBB integrity. Collectively, this provides a new perspective for exploring the relationship among circadian rhythms, gut microbes, and the BBB in aging-accompanied neurological diseases. In this review, we focus on recent advances in the interplay between circadian rhythm disturbances and gut microbiota dysbiosis, and their potential roles in the BBB disruption that occurs in AAND. Based on existing literature, we discuss and propose potential mechanisms underlying BBB damage induced by dysregulated circadian rhythms and gut microbiota, which would serve as the basis for developing potential interventions to protect the BBB in the aging population through targeting the BBB by exploiting its links with gut microbiota and circadian rhythms for treating AAND.

Acute and Repeated Ozone Exposures Differentially Affect Circadian Clock Gene Expression in Mice

Circadian rhythms have an established role in regulating physiological processes, such as inflammation, immunity, and metabolism. Ozone, a common environmental pollutant with strong oxidative potential, is implicated in lung inflammation/injury in asthmatics. However, whether O3 exposure affects the expression of circadian clock genes in the lungs is not known. In this study, changes in the expression of core clock genes are analyzed in the lungs of adult female and male mice exposed to filtered air (FA) or O3 using qRT-PCR. The findings are confirmed using an existing RNA-sequencing dataset from repeated FA- and O3 -exposed mouse lungs and validated by qRT-PCR. Acute O3 exposure significantly alters the expression of clock genes in the lungs of females (Per1, Cry1, and Rora) and males (Per1). RNA-seq data revealing sex-based differences in clock gene expression in the airway of males (decreased Nr1d1/Rev-erbα) and females (increased Skp1), parenchyma of females and males (decreased Nr1d1 and Fbxl3 and increased Bhlhe40 and Skp1), and alveolar macrophages of males (decreased Arntl/Bmal1, Per1, Per2, Prkab1, and Prkab2) and females (increased Cry2, Per1, Per2, Csnk1d, Csnk1e, Prkab2, and Fbxl3). These findings suggest that lung inflammation caused by O3 exposure affects clock genes which may regulate key signaling pathways.

Fundamental crosstalk between circadian rhythm and the intestine in the pathogenesis of inflammatory bowel disease

Crohn's disease (CD) and ulcerative colitis (UC) are the main representatives of inflammatory bowel disease (IBD), which is a chronic, relapsing inflammatory disease of the gastrointestinal tract mediated by the immune system. The pathogenesis of IBD is still not fully clarified. Currently, several studies have reported that circadian abnormality has profound effects on the immune system and intestinal microflora. Meanwhile, it is widely accepted that immune function and intestinal microbiota are two major factors in the pathogenesis of IBD. However, the role of the circadian rhythm in relation to IBD is relatively less understood and largely unexplored. The aim of this review is to present the current state of knowledge about the relationship between circadian rhythm disorders, sleep disturbance, and IBD to analyze the possibility of employing this knowledge in IBD diagnosis and treatment.

Association Between Time-of-Day of Immune Checkpoint Blockade Administration and Outcomes in Metastatic Renal Cell Carcinoma

BACKGROUND

Preclinical evidence demonstrating circadian rhythmicity within the immune system provides a rationale for hypothesis that immune checkpoint inhibitor (ICI) infusion time-of-day may serve as an actionable mechanism to improve outcomes. Herein, we explore the association between ICI time of infusion (TOI) and outcomes in metastatic renal cell carcinoma (mRCC).

METHODS

Data from patients with mRCC who received nivolumab or nivolumab/ipilimumab, in first- or second-line were retrospectively collected. Patients who received < 20% of infusions after 16:30 were assigned to the early TOI sub-cohort, while the rest were assigned to the late TOI sub-cohort. Clinical outcomes were compared across the 2 groups.

RESULTS

Among 135 patients included, 89 (65.9%) and 46 (34.1%) were assigned to early and late TOI sub-cohorts, respectively. Baseline characteristics were comparable across the 2 sub-cohorts. Objective response rate (ORR) was 36.0% with early TOI versus 29.5% with late TOI (P = .157). Median time to treatment failure (TTF) was 9.5 months in the early TOI sub-cohort versus 4.6 months in the late TOI sub-cohort with a hazard ratio (HR) of 1.405 (95% CI, 0.919-2.149; P = .11) in univariate analysis and 1.694 (95% CI, 1.064-2.698; P = .026) in multivariate analysis. Higher cut offs allocating patients into the late TOI sub-cohort yielded an incremental increase in the HR for TTF and overall survival (OS) that reached statistical significance.

CONCLUSIONS

In patients with mRCC, early TOI yielded a numerical increase in ORR, TTF and OS, with the TTF difference reaching significance in multivariate analysis. Prospective randomized studies are warranted to examine the impact of chronomodulation on outcomes with ICIs in mRCC.

Circadian Gene Variants in Diseases

The circadian rhythm is a self-sustaining 24 h cycle that regulates physiological processes within the body, including cycles of alertness and sleepiness. Cells have their own intrinsic clock, which consists of several proteins that regulate the circadian rhythm of each individual cell. The core of the molecular clock in human cells consists of four main circadian proteins that work in pairs. The CLOCK-BMAL1 heterodimer and the PER-CRY heterodimer each regulate the other pair's expression, forming a negative feedback loop. Several other proteins are involved in regulating the expression of the main circadian genes, and can therefore also influence the circadian rhythm of cells. This review focuses on the existing knowledge regarding circadian gene variants in both the main and secondary circadian genes, and their association with various diseases, such as tumors, metabolic diseases, cardiovascular diseases, and sleep disorders.

Sleep counts! Role and impact of sleep in the multimodal management of multiple sclerosis

BACKGROUND

In the last years, research on pharmacotherapy and non-pharmacological approaches to Multiple Sclerosis (MS) has significantly increased, along with a greater attention to sleep as a clinical outcome measure. This review aims to update the state of the art on the effects of MS treatments on sleep, but above all to evaluate the role of sleep and its management within the current and future therapeutic perspectives for MS patients.

METHOD

A comprehensive MEDLINE (PubMed)-based bibliographic search was conducted. This review includes the 34 papers that met the selection criteria.

RESULTS

First-line disease modifying therapies (especially the interferon-beta) seem to have a negative impact on sleep, assessed subjectively or objectively, while second-line treatments (in particular, natalizumab) do not seem to lead to the onset of daytime sleepiness (also evaluated objectively) and, in some cases, an improvement in sleep quality has been observed as well. Management of sleep is considered a major factor in modifying disease progression in pediatric MS; however, probably because only fingolimod has recently been approved in children, information is still scarce in this group of patients.

CONCLUSIONS

Studies on the effect of drugs and non-pharmacological treatments for MS on sleep are still insufficient and there is a lack of investigations on the most recent therapies. However, there is preliminary evidence that melatonin, chronotherapy, cognitive-behavioral therapy, and non-invasive brain stimulation techniques might be further assessed as adjuvant therapies, thus representing a promising field of research.

Circadian Variation of Peripheral Blood Cells in Horses Maintained in Different Environmental and Management Conditions

The aim of our study was to analyze circadian rhythm of the hematological profile of horses housed in a loose box and paddock during the different seasons (spring, summer, autumn, and winter). Blood samples were performed every 4 h for 48 consecutive hours. Red blood cells (RBCs), hemoglobin (HGB), hematocrit (HCT), white blood cells (WBCs), platelets (PLTs), and leukocyte subpopulations (neutrophils, basophils, eosinophils, lymphocytes, and monocytes) were analyzed, and, at the same time, environmental conditions were recorded. A statistically significant effect of housing conditions (p < 0.0001) was observed on all hematological values except for WBC during winter and for neutrophils (p < 0.0001) during spring and autumn. A statistically significant effect of season (p < 0.0001) was found for RBC, HCT, and PLT and for all leukocyte cells (p < 0.0001) except for basophils. The single Cosinor method revealed a daily rhythm of hematological parameters during spring in both groups, and a daily rhythm for lymphocytes and neutrophils was observed during spring and summer in horses kept in a loose box and during winter in horses housed in a paddock. Our results revealed that the response of the immune system is regulated by circadian physiology. Knowledge of the periodic temporal structure of mammals should be considered when evaluating animals' adaptation to temporizations imposed by the environment.

Multiple sclerosis and circadian rhythms: Can diet act as a treatment?

Multiple sclerosis (MS) is an autoimmune inflammatory and neurodegenerative disease of the central nervous system (CNS) with increasing incidence and prevalence. MS is associated with inflammatory and metabolic disturbances that, as preliminary human and animal data suggest, might be mediated by disruption of circadian rhythmicity. Nutrition habits can influence the risk for MS, and dietary interventions may be effective in modulating MS disease course. Chronotherapeutic approaches such as time-restricted eating (TRE) may benefit people with MS by stabilizing the circadian clock and restoring immunological and metabolic rhythms, thus potentially counteracting disease progression. This review provides a summary of selected studies on dietary intervention in MS, circadian rhythms, and their disruption in MS, including clock gene variations, circadian hormones, and retino-hypothalamic tract changes. Furthermore, we present studies that reported diurnal variations in MS, which might result from circadian disruption. And lastly, we suggest how chrononutritive approaches like TRE might counteract MS disease activity.

Clinical outcomes by infusion timing of immune checkpoint inhibitors in patients with advanced non-small cell lung cancer

BACKGROUND

We aimed to determine whether immune checkpoint inhibitors (ICI) time-of-day infusion might influence the survival of patients with advanced non-small cell lung cancer (NSCLC).

METHODS

We retrospectively analysed patients who received single-agent anti-PD-(L)1 therapy in any line between 2016 and 2021. We calculated by Cox regression models the association between the proportion of ICI infusions received after 16:30h and overall survival (OS) and progression-free survival (PFS).

RESULTS

180 patients were included, 77% received ICI as second- or further-line (median of 12 infusions/patient). The median age was 65 years (IQR 57-70), 112 patients (62%) were male, 165 (92%) were current or former tobacco smokers, 140 (78%) had performance status (PS) 0 or 1, 26 (14%) were on steroid therapy at ICI initiation. Histology was non-squamous for 139 (77%), the median number of metastatic sites was 3, and 33% had brain metastases. Patients who received at least 20% of ICI infusions after 16:30h (65 out of 180, 36%) had a statistically significant shorter median PFS as compared with patients receiving less than 20% of infusions in the evening (4.9 vs 9.4 months, log-rank p = 0.020), while numerical but not statistical shorter OS was observed (14.0 vs 26.2 months, log-rank p = 0.090). In the multivariate analysis, receiving at least 20% of evening infusions did not significantly increase the risk of death, while PS and line of treatment were significantly correlated with the OS. On the contrary, a proportion of ICI administration after 16:30h ≥20% conferred an HR for the PFS of 1.44 (95% CI: 1.01-2.05, p = 0.043), but this prognostic effect was not found when including in the model the total number of ICI infusions received (HR 1.20, 95% CI: 0.83-1.75, p = 0.329).

CONCLUSION

Time-of-day infusion of ICI may impact the survival of patients with advanced NSCLC. Underlying prognostic characteristics and the number of infusions received could represent conceivable confounding factors, linked to increased variance related to ICI infusion timing. Nonetheless, further studies may unravel chronobiological mechanisms modulating ICI efficacy.

Potential effects of shift work on skin autoimmune diseases

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

The underexplored links between cancer and the internal body climate: Implications for cancer prevention and treatment

In order to effectively manage and cure cancer we should move beyond the general view of cancer as a random process of genetic alterations leading to uncontrolled cell proliferation or simply a predictable evolutionary process involving selection for traits that increase cell fitness. In our view, cancer is a systemic disease that involves multiple interactions not only among cells within tumors or between tumors and surrounding tissues but also with the entire organism and its internal "milieu". We define the internal body climate as an emergent property resulting from spatial and temporal interactions among internal components themselves and with the external environment. The body climate itself can either prevent, promote or support cancer initiation and progression (top-down effect; i.e., body climate-induced effects on cancer), as well as be perturbed by cancer (bottom-up effect; i.e., cancer-induced body climate changes) to further favor cancer progression and spread. This positive feedback loop can move the system towards a "cancerized" organism and ultimately results in its demise. In our view, cancer not only affects the entire system; it is a reflection of an imbalance of the entire system. This model provides an integrated framework to study all aspects of cancer as a systemic disease, and also highlights unexplored links that can be altered to both prevent body climate changes that favor cancer initiation, progression and dissemination as well as manipulate or restore the body internal climate to hinder the success of cancer inception, progression and metastasis or improve therapy outcomes. To do so, we need to (i) identify cancer-relevant factors that affect specific climate components, (ii) develop 'body climate biomarkers', (iii) define 'body climate scores', and (iv) develop strategies to prevent climate changes, stop or slow the changes, or even revert the changes (climate restoration).

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.

Circadian rhythm and disease: Relationship, new insights, and future perspectives

The circadian system is responsible for internal functions and regulation of the organism according to environmental cues (zeitgebers). Circadian rhythm dysregulation or chronodisruption has been associated with several diseases, from mental to autoimmune diseases, and with life quality change. Following this, some therapies have been developed to correct circadian misalignments, such as light therapy and chronobiotics. In this manuscript, we describe the circadian-related diseases so far investigated, and studies reporting relevant data on this topic, evidencing this relationship, are included. Despite the actual limitations in published work, there is clear evidence of the correlation between circadian rhythm dysregulation and disease origin/development, and, in this way, clock-related therapies emerge as great progress in the clinical field. Future improvements in such interventions can lead to the development of successful chronotherapy strategies, deeply contributing to enhanced therapeutic outcomes.

Melatonin alleviates the immune response and improves salivary gland function in primary Sjögren's syndrome

Primary Sjögren's syndrome (pSS) is an autoimmune disease that primarily affects exocrine glands and is characterized by sicca syndrome and systemic manifestation. Mounting evidence indicates that circadian clocks are involved in the onset and progression of autoimmune diseases, including rheumatic arthritis, multiple sclerosis, and systemic lupus erythematosus. However, few studies have reported the expression of clock genes in pSS. There is no ideal therapeuticmethod for pSS, the management of pSS is mainly palliative, aims to alleviate sicca symptoms. Melatonin is a neuroendocrine hormone mainly secreted by the pineal gland that plays an important role in the maintenance of the circadian rhythm and immunomodulation. Hence, this study aimed to analyse the circadian expression profile of clock genes in pSS, and further evaluate the therapeutic potential of melatonin in pSS. We discovered a distinct clock gene expression profile in an animal model and in patients with pSS. More importantly, melatonin administration regulated clock gene expression, improved the hypofunction of the salivary glands, and inhibited inflammatory development in animal model of pSS. Our study suggested that the pathogenesis of pSS might correlate with abnormal expression of circadian genes, and that melatonin might be a potential candidate for prevention and treatment of pSS.

Sleep and vaccine administration time as factors influencing vaccine immunogenicity

The immunogenicity of vaccines is affected by host, external, environmental, and vaccine factors; in addition, sleep or circadian rhythms may also have effects. With the use of vaccines to mitigate the coronavirus disease 2019 (COVID-19) pandemic, research is underway to clarify what time of the day is optimal for COVID-19 vaccination and how disturbances of circadian rhythms will affect the immunogenicity of the vaccine in shift workers. Studies on the relationship between sleep time and the immunogenicity of vaccines for influenza and hepatitis have demonstrated that less sleep time and sleep deprivation tended to adversely affect immunogenicity. In some studies, there were even sex differences in these effects. When comparing shift workers with disturbances in their circadian rhythms and those who only worked during the day, one study found less antibody formation in shift workers; however, further studies on the relationship between shift work and the immunogenicity of vaccines are needed. Studies on the relationship between vaccine administration time and immunogenicity have shown different results according to age and sex. Therefore, future studies on vaccine administration time and immunogenicity may require an individualized approach for each vaccine and each population to be vaccinated. There is accumulating evidence on the effects of sleep and vaccine administration time on the immunogenicity of vaccines. However, further studies are needed to determine whether the association between immunogenicity and circadian rhythms and vaccine administration time can be used as a basis to increase the immunogenicity for individual vaccines.

Effect of gender, age and vaccine on reactogenicity and incapacity to work after COVID-19 vaccination: a survey among health care workers

Background

The aim of our study was to assess the impact the impact of gender and age on reactogenicity to three COVID-19 vaccine products: Biontech/Pfizer (BNT162b2), Moderna (mRNA-1273) and AstraZeneca (ChAdOx). Additional analyses focused on the reduction in working capacity after vaccination and the influence of the time of day when vaccines were administered.

Methods

We conducted a survey on COVID-19 vaccinations and eventual reactions among 73,000 employees of 89 hospitals of the Helios Group. On May 19th, 2021 all employees received an email, inviting all employees who received at least 1 dose of a COVID-19 to participate using an attached link. Additionally, the invitation was posted in the group’s intranet page. Participation was voluntary and non-traceable. The survey was closed on June 21st, 2021.

Results

8375 participants reported on 16,727 vaccinations. Reactogenicity was reported after 74.6% of COVID-19 vaccinations. After 23.0% vaccinations the capacity to work was affected. ChAdOx induced impairing reactogenicity mainly after the prime vaccination (70.5%), while mRNA-1273 led to more pronounced reactions after the second dose (71.6%). Heterologous prime-booster vaccinations with ChAdOx followed by either mRNA-1273 or BNT162b2 were associated with the highest risk for impairment (81.4%). Multivariable analyses identified the factors older age, male gender and vaccine BNT162b as independently associated with lower odds ratio for both, impairing reactogenicity and incapacity to work. In the comparison of vaccine schedules, the heterologous combination ChAdOx + BNT162b or mRNA-1273 was associated with the highest and the homologue prime-booster vaccination with BNT162b with the lowest odds ratios. The time of vaccination had no significant influence.

Conclusions

Around 75% of the COVID-19 vaccinations led to reactogenicity and nearly 25% of them led to one or more days of work loss. Major risk factors were female gender, younger age and the administration of a vaccine other than BNT162b2. When vaccinating a large part of a workforce against COVID-19, especially in professions with a higher proportion of young and women such as health care, employers and employees must be prepared for a noticeable amount of absenteeism. Assuming vaccine effectiveness to be equivalent across the vaccine combinations, to minimize reactogenicity, employees at risk should receive a homologous prime-booster immunisation with BNT162b2.

Trial registration: The study was approved by the Ethic Committee of the Aerztekammer Berlin on May 27th, 2021 (Eth-37/21) and registered in the German Clinical Trials Register (DRKS 00025745). The study was supported by the Helios research grant HCRI-ID 2021-0272.

The role of circadian clock pathways in viral replication

The daily oscillations of bi ological and behavioural processes are controlled by the circadian clock circuitry that drives the physiology of the organism and, in particular, the functioning of the immune system in response to infectious agents. Circadian rhythmicity is known to affect both the pharmacokinetics and pharmacodynamics of pharmacological agents and vaccine-elicited immune responses. A better understanding of the role circadian pathways play in the regulation of virus replication will impact our clinical management of these diseases. This review summarises the experimental and clinical evidence on the interplay between different viral pathogens and our biological clocks, emphasising the importance of continuing research on the role played by the biological clock in virus-host organism interaction.

Time-Dependent Efficacy of Checkpoint Inhibitor Nivolumab: Results from a Pilot Study in Patients with Metastatic Non-Small-Cell Lung Cancer

HYPOTHESIS

Prior experimental and human studies have demonstrated the circadian organization of immune cells' proliferation, trafficking, and antigen recognition and destruction. Nivolumab targets T(CD8) cells, the functions, and trafficking of which are regulated by circadian clocks, hence suggesting possible daily changes in nivolumab's efficacy. Worse progression-free survival (PFS), and overall survival (OS) were reported for malignant melanoma patients receiving more than 20% of their immune checkpoint inhibitor infusions after 16:30 as compared to earlier in the day.

METHODS

Consecutive metastatic non-small-cell cancer (NSCLC) patients received nivolumab (240 mg iv q 2 weeks) at a daily time that was 'randomly' allocated for each course on a logistical basis by the day-hospital coordinators. The median time of all nivolumab administrations was computed for each patient. The study population was split into two timing groups based upon the median value of the median treatment times of all patients. CTCAE-toxicity rates, iRECIST-tumor responses, PFS and OS were computed according to nivolumab timing. PFS and OS curves were compared and hazard ratios (HR) were computed for all major categories of characteristics. Multivariable and sensitivity analyses were also performed.

RESULTS

The study accrued 95 stage-IV NSCLC patients (PS 0-1, 96%), aged 41-83 years. The majority of nivolumab administrations occurred between 9:27 and 12:54 for 48 patients ('morning' group) and between 12:55 and 17:14 for the other 47 ('afternoon' group). Median PFS (95% CL) was 11.3 months (5.5-17.1) for the 'morning' group and 3.1 months (1.5-4.6) for the 'afternoon' one (p < 0.001). Median OS was 34.2 months (15.1-53.3) and 9.6 months (4.9-14.4) for the 'morning' group and the 'afternoon' one, respectively (p < 0.001). Multivariable analyses identified 'morning' timing as a significant predictor of longer PFS and OS, with respective HR values of 0.26 (0.11-0.58) and 0.17 (0.08-0.37). The timing effect was consistent across all patient subgroups tested.

CONCLUSIONS

Nivolumab was nearly four times as effective following 'morning' as compared to 'afternoon' dosing in this cohort of NSCLC patients. Prospective timing-studies are needed to minimize the risk of resistance and to maximize the benefits from immune checkpoint inhibitors.

Introduction to Biological Rhythms: A Brief History of Chronobiology and its Relevance to Parasite Immunology

Almost every living organism on Earth is exposed to a fluctuating environment e.g., light:dark cycles, food availability, seasonal photoperiods. Most species have therefore evolved internal timing mechanisms allowing them to anticipate these rhythmic environmental changes, obtaining a survival advantage. Circadian (24 h) rhythms, in particular, regulate multiple aspects of physiology, including sleep/wake activity, feeding rhythms, and immune function. Recent studies have identified circadian rhythms in symptoms of parasite infections, rhythms in parasite schizogony, and evidence that certain parasites can manipulate host rhythms. Furthermore, efficacy of anti-parasite medications can also be modulated by timing of drug administration. Understanding the interactions between host rhythms, parasite rhythms, and disease severity is crucial to fully understand how to combat infections and reduce pathology. The aim of this review is, therefore, to provide an introduction to the field of biological rhythms, give a brief history of chronobiology research, and discuss the relevance of biological rhythms to parasite immunology.

The Effects of a Single Bout of High- or Moderate-Intensity Yoga Exercise on Circulating Inflammatory Mediators: A Pilot Feasibility Study

Background

There is a knowledge gap in the physiological effects of short-term yoga exercise interventions.

Objective

To evaluate the feasibility of a randomized controlled trial (RCT) assessing the acute effects of a yoga exercise protocol practiced at 2 intensities (high or moderate) on temporal responses of a battery of systemic circulatory cytokines in healthy yoga-naïve adults.

Methods

This study was a three-arm, pre-post pilot-RCT employing a single bout of yoga exercise intervention. Groups were high-intensity yoga (HY, n = 10), moderate-intensity yoga (MY, n = 10), and a sedentary, no-intervention control group (CON, n = 10). Blood samples were collected at baseline and post-intervention at 6 timepoints (0-, 30-, 60-, 120-, 180-minutes, and 24-hours post-intervention) and were processed with a pre-defined inflammatory panel of 13 cytokines. Heart rate (HR) was assessed with a Polar H10^® device. The PROMIS Pain intensity Questionnaire was used to assess body soreness.

Results

We demonstrate feasibility of recruitment, randomization, and retention of participants based upon predetermined metrics, including: proportion of eligible to enrolled participants (55%); recruitment period (11-months); participant retention (97%); completion rate for questionnaires (99%); completion of physiological measures (98%); and adherence to the yoga exercise protocol (88%). Cytokine levels over time were heterogeneous within and between groups. Responses of a subset of cytokines were positively correlated with 1 another in high- and moderate-intensity yoga exercise groups but not in the control group. Median values for HR were 91 (IQR: 71-95) in the HY, 95 (IQR: 88-100) in the MY, and 73 (IQR: 72-75) in the CON. Pre-post changes in body soreness after the yoga exercise intervention were most evident in the HY group.

Conclusion

Along with observed trends in select cytokines, findings encourage a more definitive trial aimed at understanding the short-term effects of yoga exercise on inflammatory immune markers and pain in sedentary healthy adults. Clinicaltrials.gov ID# NCT04444102.

The involvement of host circadian clocks in the regulation of the immune response to parasitic infections in mammals

Circadian rhythms are recurring variations of physiology with a period of ~24 hours, generated by circadian clocks located throughout the body. Studies have shown a circadian regulation of many aspects of immunity. Immune cells have intrinsic clock mechanisms, and innate and adaptive immune responses - such as leukocyte migration, magnitude of inflammation, cytokine production and cell differentiation - are under circadian control. This circadian regulation has consequences for infections including parasitic infections. In the context of Leishmania infection, the circadian clock within host immune cells modulates the magnitude of the infection and the inflammatory response triggered by the parasite. As for malaria, rhythms within the immune system were shown to impact the developmental cycles of Plasmodium parasites within red blood cells. Further, host circadian rhythms impact infections by multicellular parasites; for example, infection with helminth Trichuris muris shows different kinetics of worm expulsion depending on time of day of infection, a variation that depends on the dendritic cell clock. Although the research on the circadian control of immunity in the context of parasitic infections is in its infancy, the research reviewed here suggests a crucial involvement of host circadian rhythms in immunity on the development and progression of parasitic infections.

Circadian Rhythm Effects on the Molecular Regulation of Physiological Systems

Nearly every system within the body contains an intrinsic cellular circadian clock. The circadian clock contributes to the regulation of a variety of homeostatic processes in mammals through the regulation of gene expression. Circadian disruption of physiological systems is associated with pathophysiological disorders. Here, we review the current understanding of the molecular mechanisms contributing to the known circadian rhythms in physiological function. This article focuses on what is known in humans, along with discoveries made with cell and rodent models. In particular, the impact of circadian clock components in metabolic, cardiovascular, endocrine, musculoskeletal, immune, and central nervous systems are discussed. © 2021 American Physiological Society. Compr Physiol 11:1-30, 2021.

Combination of Genomic and Transcriptomic Approaches Highlights Vascular and Circadian Clock Components in Multiple Sclerosis

Aiming at exploring vascular components in multiple sclerosis (MS) with brain outflow disturbance, we combined transcriptome analysis in MS internal jugular vein (IJV) wall with WES in MS families with vertical transmission of disease. Main results were the differential expression in IJV wall of 16 MS-GWAS genes and of seven genes (GRIN2A, GRIN2B, IL20RB, IL26, PER3, PITX2, and PPARGC1A) not previously indicated by GWAS but encoding for proteins functionally interacting with MS candidate gene products. Strikingly, 22/23 genes have been previously associated with vascular or neuronal traits/diseases, nine encoded for transcriptional factors/regulators and six (CAMK2G, GRIN2A, GRIN2B, N1RD1, PER3, PPARGC1A) for circadian entrainment/rhythm components. Among the WES low-frequency (MAF ≤ 0.04) SNPs (n = 7) filtered in the 16 genes, the NR1D1 rs17616365 showed significantly different MAF in the Network for Italian Genomes affected cohort than in the 1000 Genome Project Tuscany samples. This pattern was also detected in five nonintronic variants (GRIN2B rs1805482, PER3 rs2640909, PPARGC1A rs2970847, rs8192678, and rs3755863) in genes coding for functional partners. Overall, the study proposes specific markers and low-frequency variants that might help (i) to understand perturbed biological processes in vascular tissues contributing to MS disease, and (ii) to characterize MS susceptibility genes for functional association with disease-pathways.

Effect of immunotherapy time-of-day infusion on overall survival among patients with advanced melanoma in the USA (MEMOIR): a propensity score-matched analysis of a single-centre, longitudinal study

BACKGROUND

The dependence of the adaptive immune system on circadian rhythm is an emerging field of study with potential therapeutic implications. We aimed to determine whether specific time-of-day patterns of immune checkpoint inhibitor infusions might alter melanoma treatment efficacy.

METHODS

Melanoma Outcomes Following Immunotherapy (MEMOIR) is a longitudinal study of all patients with melanoma who received ipilimumab, nivolumab, or pembrolizumab, or a combination of these at a single tertiary cancer centre (Winship Cancer Institute of Emory University, Atlanta, GA, USA). For this analysis, we collected deidentified participant-level data from the MEMOIR database for adults (age ≥18 years) diagnosed with stage IV melanoma between 2012 and 2020. Those who received fewer than four infusions were excluded. Standard of care doses were used, with modifications at the treating physicians' discretion. The primary outcome was overall survival, defined as death from any cause and indexed from date of first infusion of immune checkpoint inhibitor. We calculated the association between overall survival and proportion of infusions of immune checkpoint inhibitors received after 1630 h (a composite time cutoff derived from seminal studies of the immune-circadian rhythm to represent onset of evening) using Cox regression and propensity score-matching on age, Eastern Cooperative Oncology Group performance status, serum lactate dehydrogenase concentration, and receipt of corticosteroids and radiotherapy. Treatment-related adverse events that led to change or discontinuation of immune checkpoint inhibitors were also assessed.

FINDINGS

Between Jan 1, 2012, and Dec 31, 2020, 481 patients with melanoma received treatment with immune checkpoint inhibitors at the study centre, of whom 299 had stage IV disease and were included in this study; median follow-up was 27 months (IQR 14 to 47). In the complete unmatched sample, 102 (34%) patients were female and 197 (66%) were male, with a median age of 61 years (IQR 51 to 72). Every additional 20% of infusions of immune checkpoint inhibitors received after 1630 h (among all infusions received by a patient) conferred an overall survival hazard ratio (HR) of 1·31 (95% CI 1·00 to 1·71; p=0·046). A propensity score-matched analysis of patients who did (n=73) and did not (n=73) receive at least 20% of their infusions of immune checkpoint inhibitors after 1630 h (54 [37%] of 146 patients were women and 92 [63%] were men, with a median age of 58 years [IQR 48 to 68]) showed that having at least 20% of infusions in the evening was associated with shorter overall survival (median 4·8 years [95% CI 3·9 to not estimable] vs not reached; HR 2·04 [1·04 to 4·00; p=0·038]). This result remained robust to multivariable proportional hazards adjustment with (HR 1·80 [1·08 to 2·98; p=0·023]) and without (2·16 [1·10 to 4·25; p=0·025]) inclusion of the complete unmatched study sample. The most common adverse events were colitis (54 [18%] of 299 patients), hepatitis (27 [9%]), and hypophysitis (15 [5%]), and there were no treatment-related deaths.

INTERPRETATION

Our findings are in line with an increasing body of evidence that adaptive immune responses are less robust when initially stimulated in the evening than if stimulated in the daytime. Although prospective studies of the timing of immune checkpoint inhibitor infusions are warranted, efforts towards scheduling infusions before mid-afternoon could be considered in the multidisciplinary management of advanced melanoma.

FUNDING

National Institutes of Health, American Society for Radiation Oncology and Melanoma Research Alliance, and Winship Cancer Institute.

Circadian Clock Regulates Inflammation and the Development of Neurodegeneration

The circadian clock regulates numerous key physiological processes and maintains cellular, tissue, and systemic homeostasis. Disruption of circadian clock machinery influences key activities involved in immune response and brain function. Moreover, Immune activation has been closely linked to neurodegeneration. Here, we review the molecular clock machinery and the diurnal variation of immune activity. We summarize the circadian control of immunity in both central and peripheral immune cells, as well as the circadian regulation of brain cells that are implicated in neurodegeneration. We explore the important role of systemic inflammation on neurodegeneration. The circadian clock modulates cellular metabolism, which could be a mechanism underlying circadian control. We also discuss the circadian interventions implicated in inflammation and neurodegeneration. Targeting circadian clocks could be a potential strategy for the prevention and treatment of inflammation and neurodegenerative diseases.

Circadian clock genes as promising therapeutic targets for autoimmune diseases

Circadian rhythm is a natural, endogenous process whose physiological functions are controlled by a set of clock genes. Disturbance of the clock genes have detrimental effects on both innate and adaptive immunity, which significantly enhance pro-inflammatory responses and susceptibility to autoimmune diseases via strictly controlling the individual cellular components of the immune system that initiate and perpetuate the inflammation pathways. Autoimmune diseases, especially rheumatoid arthritis (RA), often exhibit substantial circadian oscillations, and circadian rhythm is involved in the onset and progression of autoimmune diseases. Mounting evidence indicate that the synthetic ligands of circadian clock genes have the property of reducing the susceptibility and clinical severity of subjects. This review supplies an overview of the roles of circadian clock genes in the pathology of autoimmune diseases, including BMAL1, CLOCK, PER, CRY, REV-ERBα, and ROR. Furthermore, summarized some circadian clock genes as candidate genes for autoimmune diseases and current advancement on therapy of autoimmune diseases with synthetic ligands of circadian clock genes. The existing body of knowledge demonstrates that circadian clock genes are inextricably linked to autoimmune diseases. Future research should pay attention to improve the quality of life of patients with autoimmune diseases and reduce the effects of drug preparation on the normal circadian rhythms.

Circadian Variation in Efficacy of Medications

Although much has been learned about circadian clocks and rhythms over the past few decades, translation of this foundational science underlying the temporal regulation of physiology and behavior to clinical applications has been slow. Indeed, acceptance of the modern study of circadian rhythms has been blunted because the phenomenology of cyclic changes had to counteract the 20th century dogma of homeostasis in the biological sciences and medicine. We are providing this review of clinical data to highlight the emerging awareness of circadian variation in efficacy of medications for physicians, clinicians, and pharmacists. We are suggesting that gold-standard double-blind clinical studies should be conducted to determine the best time of day for optimal effectiveness of medications; also, we suggest that time of day should be tracked and reported as an important biological variable in ongoing clinical studies hereafter. Furthermore, we emphasize that time of day is, and should be considered, a key biological variable in research design similar to sex. In common with biomedical research data that have been historically strongly skewed toward the male sex, most pharmaceutical data have been skewed toward morning dosing without strong evidence that this is the optimal time of efficacy.

Hallmarks of Health

Health is usually defined as the absence of pathology. Here, we endeavor to define health as a compendium of organizational and dynamic features that maintain physiology. The biological causes or hallmarks of health include features of spatial compartmentalization (integrity of barriers and containment of local perturbations), maintenance of homeostasis over time (recycling and turnover, integration of circuitries, and rhythmic oscillations), and an array of adequate responses to stress (homeostatic resilience, hormetic regulation, and repair and regeneration). Disruption of any of these interlocked features is broadly pathogenic, causing an acute or progressive derailment of the system coupled to the loss of numerous stigmata of health.

Recent advances in modulators of circadian rhythms: an update and perspective

Circadian rhythm is a universal life phenomenon that plays an important role in maintaining the multiple physiological functions and regulating the adaptability to internal and external environments of flora and fauna. Circadian alignment in humans has the greatest effect on human health, and circadian misalignment is closely associated with increased risk for metabolic syndrome, cardiovascular diseases, neurological diseases, immune diseases, cancer, sleep disorders, and ophthalmic diseases. The recent description of clock proteins and related post-modification targets was involved in several diseases, and numerous lines of evidence are emerging that small molecule modulators of circadian rhythms can be used to rectify circadian disorder. Herein, we attempt to update the disclosures about the modulators targeting core clock proteins and related post-modification targets, as well as the relationship between circadian rhythm disorders and human health as well as the therapeutic role and prospect of these small molecule modulators in circadian rhythm related disease.

It's time to think about circadian rhythms

We here introduce a Review Series focussing on the important influences circadian rhythms have on immune responses. The three reviews in this series, expertly curated by Rachel Edgar, discuss how the cyclic oscillations in our cellular clock affect the innate and adaptive immune response, and how interactions with the intestinal microbiota, themselves subject to daily oscillations, also influence immune responses. As we understand more about these mechanisms, by which chronobiology contributes to immunology, it is becoming increasingly clear that they have important functions in maintaining health, influence autoimmunity and may contribute to the effectiveness of vaccinations.

Circadian Rhythm Protein Bmal1 Modulates Cartilage Gene Expression in Temporomandibular Joint Osteoarthritis via the MAPK/ERK Pathway

The purpose of this study was to elucidate the role of the circadian gene Bmal1 in human cartilage and its crosstalk with the MAPK/ERK signaling pathway in temporomandibular joint osteoarthritis (TMJ-OA). We verified the periodical variation of the circadian gene Bmal1 and then established a modified multiple platform method (MMPM) to induce circadian rhythm disturbance leading to TMJ-OA. IL-6, p-ERK, and Bmal1 mRNA and protein expression levels were assessed by real-time RT-PCR and immunohistochemistry. Chondrocytes were treated with an ERK inhibitor (U0126), siRNA and plasmid targeting Bmal1 under IL-6 simulation; then, the cells were subjected to Western blotting to analyze the relationship between Bmal1 and the MAPK/ERK pathway. We found that sleep rhythm disturbance can downregulate the circadian gene BMAL-1 and improve phosphorylated ERK (p-ERK) and IL-6 levels. Furthermore, Bmal1 siRNA transfection was sufficient to improve the p-ERK level and aggravate OA-like gene expression changes under IL-6 stimulation. Bmal1 overexpression relieved the alterations induced by IL-6, which was consistent with the effect of U0126 (an ERK inhibitor). However, we also found that BMAL1 upregulation can decrease ERK phosphorylation, whereas ERK downregulation did not change BMAL1 expression. Collectively, this study provides new insight into the regulatory mechanism that links chondrocyte BMAL1 to cartilage maintenance and repair in TMJ-OA via the MAPK/ERK pathway and suggests that circadian rhythm disruption is a risk factor for TMJ-OA.