Circadian clock proteins and immunity

The transcription factor BMAL1 inhibits endothelial cell apoptosis by targeting STAT6 to repress its expression

Corneal transparency is critical for optimal visual function, and corneal neovascularization represents the primary cause of visual impairment globally. Recent studies have identified the transcription factor BMAL1 as a significant regulator of angiogenesis. However, its specific role and underlying mechanisms in endothelial cell apoptosis remain inadequately understood. This study seeks to elucidate the role and underlying mechanisms of BMAL1 in endothelial cell apoptosis by employing genetic modification, alkali-burned mouse corneal neovascularization models, lentiviral transfection, proteomic analysis, and other complementary methodologies. Our results showed that BMAL1 expression is significantly elevated in corneal neovascularization induced by alkali burn and removal of Bmal1 in endothelial cells resulted in the suppression of corneal neovascularization in alkali burn mouse models. In vivo experiments have demonstrated that the knockout of Bmal1 in endothelial cells leads to an increase in endothelial cell apoptosis. Complementary in vitro studies revealed that overexpression of BMAL1 in endothelial cells inhibits apoptosis, while knockdown of BMAL1 promotes apoptosis. Proteomic analysis identified STAT6 as a downstream target of BMAL1 involved in the regulation of endothelial cell apoptosis. Further cell salvage experiments confirmed that BMAL1 modulates endothelial cell apoptosis through the regulation of STAT6 expression. Finally, the results of dual-luciferase reporter assay demonstrated that BMAL1 exerts transcriptional repressive effects on the promoter bound by STAT6. This study elucidates the novel role and mechanism of BMAL1 in the regulation of angiogenesis and endothelial cell apoptosis, thereby identifying a potential therapeutic target for the treatment of vascular diseases such as corneal neovascularization.

Identification and Validation of Circadian Rhythm-Related Genes Involved in Intervertebral Disc Degeneration and Analysis of Immune Cell Infiltration via Machine Learning

Background

Low back pain is a significant burden worldwide, and intervertebral disc degeneration (IVDD) is identified as the primary cause. Recent research has emphasized the significant role of circadian rhythms (CRs) and immunity in affecting intervertebral discs (IVD). However, the influence of circadian rhythms and immunity on the mechanism of IVDD remains unclear. This study aimed to identify and validate key rhythm-related genes in IVDD and analyze their correlation with immune cell infiltration.

Methods

Two gene expression profiles related to IVDD and rhythm-related genes were obtained from the Gene Expression Omnibus and GeneCards databases to identify differentially expressed rhythm-related genes (DERGs). Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene set enrichment analysis (GSEA) were conducted to explore the biological functions of these genes. LASSO regression and SVM algorithms were employed to identify hub genes. We subsequently investigated the correlation between hub rhythm-related genes and immune cell infiltration. Finally, nucleus pulposus-derived mesenchymal stem cells (NPMSCs) were isolated from normal and degenerative human IVD tissues. Hub rhythm-related genes expression in NPMSCs was confirmed by real-time quantitative PCR (RT-qPCR).

Results

Six hub genes related to CRs (CCND1, FOXO1, FRMD8, NTRK2, PRRT1, and TFPI) were screened out. Immune infiltration analysis revealed that the IVDD group had significantly more M0 macrophages and significantly fewer follicular helper T cells than those of the control group. Specifically, M0 macrophages were significantly associated with FRMD8, PRRT1, and TFPI. T follicular helper cells were significantly associated with FRDM8, FOXO1, and CCND1. We further confirmed that CCND1, FRMD8, NTRK2, and TFPI were dysrhythmic within NPMSCs from degenerated IVD in vitro.

Conclusion

Six genes (CCND1, FOXO1, FRMD8, NTRK2, PRRT1 and TFPI) linked to circadian rhythms associated with IVDD progression, together with immunity. The identification of these DEGs may provide new insights for the diagnosis and treatment of IVDD.

A light-regulated circadian timer optimizes neutrophil bactericidal activity to boost daytime immunity

The immune response exhibits strong circadian rhythmicity, with enhanced bacterial clearance often synchronized with an organism's active phase. Despite providing the bulk of cellular antibacterial defense, the neutrophil clockwork is poorly understood. Here, we used larval zebrafish to explore the role of clock genes in neutrophils during infection. Per2 was required in neutrophils for reactive oxygen species (ROS) production and bacterial killing by enhancing infection-responsive expression of high-mobility group box 1a (hmgb1a). The Cry binding domain of Per2 was required for regulation of neutrophil bactericidal activity, and neutrophils lacking Cry1a had elevated bactericidal activity and infection-responsive hmgb1a expression. A conserved cis-regulatory element with BMAL1 and nuclear factor κB binding motifs gated infection-responsive hmgb1a expression to the light phase. Mutagenesis of the BMAL1 motif in neutrophils blunted the priming effect of light on bactericidal activity and hmgb1a expression. These findings identify a light-responsive cell-intrinsic timer that controls time-of-day variations in antibacterial activity.

Roles of circadian clocks in macrophage metabolism: implications in inflammation and metabolism of lipids, glucose, and amino acids

Macrophages are essential immune cells that play crucial roles in inflammation and tissue homeostasis and are important regulators of metabolic processes, such as the metabolism of glucose, lipids, and amino acids. The regulation of macrophage metabolism by circadian clock genes has been emphasized in many studies. Changes in metabolic profiles occurring after the perturbation of macrophage circadian cycles may underlie the etiology of several diseases. Specifically, chronic inflammatory disorders, such as atherosclerosis, diabetes, cardiovascular diseases, and liver dysfunction, are associated with poor macrophage metabolism. Developing treatment approaches that target metabolic and immunological ailments requires an understanding of the complex relationships among clock genes, disease etiology, and macrophage metabolism. This review explores the molecular mechanisms through which clock genes regulate lipid, amino acid, and glucose metabolism in macrophages and discusses their potential roles in the development and progression of metabolic disorders. The findings underscore the importance of maintaining circadian homeostasis in macrophage function as a promising avenue for therapeutic intervention in diseases involving metabolic dysregulation, given its key roles in inflammation and tissue homeostasis. Moreover, reviewing the therapeutic implications of circadian rhythm in macrophages can help minimize the side effects of treatment. Novel strategies may be beneficial in treating immune-related diseases caused by shifted and blunted circadian rhythms via light exposure, jet lag, seasonal changes, and shift work or disruption to the internal clock (such as stress or disease).

Integrating bioinformatics and machine learning to discover sumoylation associated signatures in sepsis

Small Ubiquitin-like MOdifier-mediated modification (SUMOylation) is associated with sepsis; however, its molecular mechanism remains unclear. Herein, hub genes and regulatory mechanisms in sepsis was investigated. The GSE65682 and GSE95233 datasets were extracted from public databases. Differential analysis and Weighted Gene Co-expression Network Analysis (WGCNA) were conducted in GSE65682 to identify differentially expressed genes (DEGs) and key module genes. Candidate genes were derived by intersecting with SUMOylation-related genes (SUMO-RGs). The Least Absolute Shrinkage and Selection Operator (LASSO) and Support Vector Machine-Recursive Feature Elimination (SVM-RFE) were utilized to identify significant feature genes. The convergence of those genes was utilized for diagnostic assessment and expression validation. Hub genes were defined as those exhibiting an area under the curve (AUC) greater than 0.7, significant gene expression, and a consistent trend. Localization and functional analyses of hub genes were conducted to enhance the understanding of these genes. Immune analysis, regulatory network construction, and drug prediction were performed. Six hub genes were identified: RORA, L3MBTL2, PHC1, RPA1, CHD3, and RANGAP1. These genes possessed considerable diagnostic significance for sepsis and were also markedly downregulated in the condition. Hub genes were predominantly enriched in the ribosome pathway and exhibited a strong correlation with differential immune cells. Activated CD8 + T cells exhibited a positive correlation with RORA. Based on the predicted and established regulatory network, AC004687.1 was observed to modulate PHC1 expression via hsa-miR- 142 - 5p. A total of six hub genes (RORA, L3MBTL2, PHC1, RPA1, CHD3, and RANGAP1) associated with SUMOylation was identified in sepsis in the current study. The findings are likely to aid in the differentiation between control and disease states, offering substantiation for the diagnosis of sepsis.

Single-cell RNA-seq analysis identifies the atlas of lymph fluid and reveals a sepsis-related T cell subset

The lymphoid cycle serves as a sentinel of the immune response, yet the cell subtypes and immune properties within lymph fluid remain unclear. This study describes a comprehensive characterization of immune cells in rat lymph fluid using single-cell RNA sequencing, identifying a unique subset of CD4+ T cells (CD4_Icos) that suppresses inflammation in early sepsis. Trajectory analysis reveals that CD4+Icos+ T cells can differentiate into regulatory T cells (Tregs). Transferring CD4+Icos+ T cells alleviates CLP-induced organ injury, while CD4+ Icos-knockout (KO) mice show reduced Treg numbers, increased inflammation, and higher mortality. Further experiments identify Npas2 as an Icos-specific transcription factor regulating Icos expression and promoting the differentiation of CD4+Icos+ T cells. Clinical data show a negative correlation between ICOS expression in CD4+ T cells and clinical outcomes in septic patients. These findings highlight the protective role of CD4+ T cells in modulating immune responses and mitigating sepsis progression.

Circadian Rhythm Dysregulation in Inflammatory Bowel Disease: Mechanisms and Chronotherapeutic Approaches

Inflammatory bowel disease (IBD), comprising ulcerative colitis (UC) and Crohn's disease (CD), is characterized by chronic intestinal inflammation. Recent research has highlighted the significant interplay between IBD pathogenesis and circadian rhythms. This review synthesizes current evidence regarding circadian regulation in IBD, covering three main areas: (1) circadian rhythms in intestinal physiology, (2) circadian disruption patterns in IBD patients, and (3) the role of clock genes in IBD pathogenesis. We discuss how these findings may inform novel chronotherapeutic approaches for IBD treatment. Future research directions that could facilitate translation of chronobiological insights into clinical applications are also explored.

Generation of Myeloid-Specific Bmal1 Knockout Mice and Identification of Bmal1-Regulated Ferroptosis in Macrophages

Circadian clocks have a fundamental role in many physiological processes. Bmal1 (basic helix-loop-helix ARNT like 1) is a central master circadian clock gene. The global Bmal1 knockout mice were shown to have a loss of circadian rhythms, acceleration of aging, and shortened life span. However, global Bmal1 knockout mice did not exactly reflect the Bmal1 function in specific cell or tissue types. To address the importance of circadian rhythms in macrophages, we generated myeloid-specific Bmal1 knockout mice. The efficacy of Bmal1 gene deletion in macrophages was identified at DNA, transcription, protein levels, and function. In contrast to global Bmal1 knockout mice, Bmal1flox/flox and Bmal1mye-/- mice did not exhibit aging phenotypes. However, the deletion of Bmal1 resulted in a loss of rhythmic expression of the circadian genes in macrophages. RNA-Seq revealed that Bmal1 regulated the expression of cell death-related genes in macrophages. Furthermore, these genes have been identified as clock-controlled genes in rhythmic cell models, and Bmal1 controlled the rhythmic expression of these genes in macrophages. Finally, Bmal1 inhibited RSL3-induced ferroptosis in macrophages through Phgdh. In summary, the model of myeloid-specific Bmal1 knockout mice was successfully constructed, providing a tool for the study of the roles of Bmal1 in macrophages and the peripheral circadian clock. Meanwhile, Bmal1 regulates ferroptosis in macrophages.

Cellular senescence in tumor immune escape: Mechanisms, implications, and therapeutic potential

Cellular senescence, a hallmark of aging, has emerged as a captivating area of research in tumor immunology with profound implications for cancer prevention and treatment. In the tumor microenvironment, senescent cells exhibit a dual role, simultaneously hindering tumor development through collaboration with immune cells and evading immune cell attacks by upregulating immunoinhibitory proteins. However, the intricate immune escape mechanism of cellular senescence in the tumor microenvironment remains a subject of intense investigation. Chronic inflammation is exacerbated by cellular senescence through the upregulation of pro-inflammatory factors such as interleukin-1β, thereby augmenting the risk of tumorigenesis. Additionally, the interplay between autophagy and cellular senescence adds another layer of complexity. Autophagy, known to slow down the aging process by reducing p53/p21 levels, may be downregulated by cellular senescence. To harness the therapeutic potential of cellular senescence, targeting its immunological aspects has gained significant attention. Strategies such as immune checkpoint inhibitors and T-cell senescence inhibition are being explored in the context of cellular senescence immunotherapy. In this comprehensive review, we provide a compelling overview of the regulation of cellular senescence and delve into the influencing factors, including chronic inflammation, autophagy, and circadian rhythms, associated with senescence in the tumor microenvironment. We specifically focus on unraveling the enigmatic dual role of cellular senescence in tumor immune escape. By deciphering the intricate nature of cellular senescence in the tumor microenvironment, this review aims to advance our understanding and pave the way for leveraging senescence as a promising target for tumor immunotherapy applications.

Melatonin and Exercise Restore Myogenesis and Mitochondrial Dynamics Deficits Associated With Sarcopenia in iMS-Bmal1-/- Mice

Sarcopenia, a condition associated with aging, involves progressive loss of muscle mass, strength, and function, leading to impaired mobility, health, and increased mortality. The underlying mechanisms remain unclear, which limits the development of effective therapeutic interventions. Emerging evidence implicates chronodisruption as a key contributor to sarcopenia, emphasizing the role of Bmal1, a circadian clock gene critical for muscle integrity and mitochondrial function. In a skeletal muscle-specific and inducible Bmal1 knockout model (iMS-Bmal1-/-), we observed hallmark features of sarcopenia, including disrupted rhythms, impaired muscle function, and mitochondrial dysfunction. Exercise and melatonin treatment reversed these deficits independently of Bmal1. Building on these findings, the present study elucidates several mechanisms underlying these changes and the pathways by which melatonin and exercise exert their beneficial effects. Our findings indicate that iMS-Bmal1-/- mice exhibit reduced expression of satellite cell and muscle regulatory factors, indicating impaired muscle regeneration. While mitochondrial respiration remained unchanged, notable alterations in mitochondrial dynamics disrupted mitochondria in skeletal muscle. In addition, these mice showed alterations in muscle energy metabolism, compromised antioxidant defense, and inflammatory response. Remarkably, exercise and/or melatonin successfully mitigated these deficits, restoring muscle health in Bmal1-deficient mice. These findings position exercise and melatonin as promising therapeutic candidates for combating sarcopenia and emphasize the need to elucidate the molecular pathways underlying their protective effects.

Chronological Effects of Immune Checkpoint Inhibitors in Non-Small Cell Lung Cancer

Circadian rhythm is a physiological process that oscillates in a 24 h cycle. It has a complex connection with the function of the human immune system and even with the development of tumours. Previous studies demonstrated the time-dependent effects of chemotherapy and radiotherapy; however, there are few studies on the timing effects of immunotherapy. Here, we explored the differences in the efficacy of immune checkpoint inhibitors (ICIs) administered at different circadian rhythm times in non-small cell lung cancer (NSCLC). C57BL/6N lung Lewis cancer mice models were constructed. Then, mice were intraperitoneally injected with saline or anti-PD-1 antibody at 7 AM or 7 PM, The expression of PD-L1 was detected by flow cytometry, and the expressions of clock gene BMAL1 and PER2 were detected by polymerase chain reaction (PCR) after treatment. A retrospective analysis was conducted on patients with NSCLC who received ICIs in our department from June 2020 to December 2022. Animal experiments showed that mice treated with ICIs in the morning showed slower tumour growth and smaller tumour volumes than those in the afternoon, accompanied by increased expression of BMAL1 and PER2 and suppression of PD-L1 expression. Retrospective analysis showed that patients who received ICIs in the afternoon (after 12:00) had significantly longer progression-free survival than those in the morning (before 12:00) (median was 16.5 months versus 9.8 months, respectively, p = 0.031, hazard ratio = 1.87). These findings suggest that immunotherapy may have time dependence, offering a novel therapeutic strategy.

Circadian clock is critical for fungal pathogenesis by regulating zinc starvation response and secondary metabolism

Circadian clocks are known to modulate host immune responses to pathogen infections, yet their role in influencing pathogen pathogenesis remains unclear. Here, we investigated the role of circadian clocks in regulating the pathogenesis of the fungal pathogen Fusarium oxysporum, which has multiple genes homologous to the Neurospora crassa frq due to gene duplication events, with Fofrq1 being the primary circadian clock gene. The pathogenesis of F. oxysporum in plants is controlled by its circadian clock, with infections causing severe disease symptoms at dawn. Notably, disruption of clock genes dramatically reduces fungal pathogenicity. Circadian clocks regulate the rhythmic expression of several transcription factors, including FoZafA, which enables the pathogen to adapt to zinc starvation within the plant, and FoCzf1, which governs the production of the toxin fusaric acid. Together, our findings highlight the critical roles of circadian clocks in F. oxysporum pathogenicity by regulating zinc starvation response and secondary metabolite production.

Adaptive evolution of traits for parasitism and pathogen transmission potential in bat flies

Deciphering the mechanisms underlying the transmission and spillover of zoonoses from reservoir hosts is essential in preventing future global pandemics. Bat flies-obligate blood-feeding ectoparasites of bats-are known carriers of diverse viruses. Here, we conducted a de novo assembly of a chromosome-level genome for the bat fly species Phthiridium sp. Comparative genomic analysis unveiled genes associated with specialized traits, such as the loss of eyes and wings, as well as elongated legs, which have adapted to parasitism on the dense fur of bats. Utilizing small RNA sequencing, we identified a spectrum of known and previously unclassified viruses in bat flies. Notably, experimental evidence indicated that bat flies can also feed on mammalian hosts other than bats, suggesting the potential for the spillover of bat-borne viruses. Furthermore, we demonstrated the role of the bat fly's RNA interference pathway in influencing the diversity and evolution of viruses. In summary, this study not only presents a new genome catalog to unveil the evolutionary mechanisms underpinning bat fly parasitism, but also provides a novel research system that can be used to investigate the mechanisms of cross-species transmission of bat-borne viruses and the co-evolution of bats and viruses.

Jiawei Yanghe Decoction alleviates pulmonary sarcoidosis by upregulating NR1D1/2 and suppressing Th17 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Jiawei Yanghe Decoction (JWYHD) is a modified version traditional Chinese medicine formula Yanghe Decoction which has been used to treat various autoimmune diseases. However, the effect of JWYHD on pulmonary sarcoidosis remains unclear.

AIM OF THE STUDY

This study aimed to determine the therapeutic efficacy and potential mechanism of action of JWYHD in pulmonary sarcoidosis.

MATERIALS AND METHODS

A murine model of sarcoidosis was established by intravenous injection of inactivated Propionibacterium acnes and mature dendritic cells to assess the efficacy of JWYHD. Lung tissue mRNA sequencing was conducted to identify the targets of JWYHD's action. Molecular docking verified of the interaction between identified compounds and key targets.

RESULTS

JWYHD treatment alleviated the formation of granulomas in the lung tissue of sarcoidosis model mice. JWYHD significantly attenuated the pulmonary accumulation of macrophages and CD4+T lymphocytes in sarcoidosis mice, and effectively suppressed the proportion of Th17 cells and the levels of IL-17A and TNF-α in BALF, which are pivotal in the pathogenesis of granuloma formation and progression. The therapeutic efficacy of JWYHD was found to be equivalent to that of prednisone. RNA-seq revealed that JWYHD upregulated Nr1d1/2 expression in the lung tissue. Nr1d1/2 is highly expressed in Th17 cells and regulates their differentiation. The NR1D1/2 agonist SR9009 could inhibit Th17 cell proportion and reduce the formation of pulmonary granuloma, exhibiting effects similar to those of JWYHD. Molecular docking result showed that Cyclocephaloside II, Epimedin B, Glycyrrhetic acid, Glycyrrhizic acid, Uralsaponin B, and Uralsaponin U may be key compounds in JWYHD for the treatment of pulmonary sarcoidosis, which had a strong binding ability for NR1D1/2.

CONCLUSIONS

JWYHD might exert a therapeutic benefit in pulmonary sarcoidosis through upregulating NR1D1/2 and suppressing Th17 cells. NR1D1/2 might serve as a therapeutic target for the treatment of pulmonary sarcoidosis.

Rev-erb-α antagonism in alveolar macrophages protects against pneumococcal infection in elderly mice

Circadian rhythms control the diurnal nature of many physiological, metabolic, and immune processes. We hypothesized that age-related impairments in circadian rhythms are associated with high susceptibility to bacterial respiratory tract infections. Our data show that the time-of-day difference in the control of Streptococcus pneumoniae infection is altered in elderly mice. A lung circadian transcriptome analysis revealed that aging alters the daily oscillations in the expression of a specific set of genes and that some pathways that are rhythmic in young-adult mice are non-rhythmic or time shifted in elderly mice. In particular, the circadian expression of the clock component Rev-erb-α and apelin/apelin receptor was altered in elderly mice. In young-adult mice, we discovered an interaction between Rev-erb-α and the apelinergic axis that controls host defenses against S. pneumoniae via alveolar macrophages. Pharmacological repression of Rev-erb-α in elderly mice resulted in greater resistance to pneumococcal infection. These data suggest the causative role of age-associated impairments in circadian rhythms on respiratory infections and have clinical relevance.

Adult Diel Locomotor Behaviour in the Agricultural Pest Plutella xylostella Reflects Temperature-Driven and Light-Repressed Regulation Rather than Coupling to Circadian Clock Gene Rhythms

The diamondback moth, Plutella xylostella, is arguably the most economically impactful and widespread lepidopteran pest. Though the larval P. xylostella life stage is responsible for most of this cost through the consumption of crops, it is the adult form that spreads the pest to fresh crops all around the world, seeking them out in a seasonally expanding range. It is therefore important to understand the activity rhythms of adult P. xylostella in response to environmental cues such as light and temperature. We analysed diel rhythms in both adult clock gene expression and locomotor behaviour for the ROTH P. xylostella strain. Real-time quantitative PCR analyses of P. xylostella demonstrated diel rhythms for transcripts of the clock genes period and timeless under both entrained and free-running conditions indicating the presence of a functional daily timekeeping mechanism. However, adult locomotor rhythms exhibited temperature-driven and light-repressed regulation rather than circadian control. Thus, our analyses show a lack of coupling between the P. xylostella circadian clock and adult locomotor behaviour, which may be relevant in predicting the activity patterns of this agricultural pest.

Implications of circadian disruption on intervertebral disc degeneration: The mediating role of sympathetic nervous system

The circadian clock orchestrates a broad spectrum of physiological processes, crucially modulating human biology across an approximate 24-hour cycle. The circadian disturbances precipitated by modern lifestyle contribute to the occurrence of low back pain (LBP), mainly ascribed to intervertebral disc degeneration (IVDD). The intervertebral disc (IVD) exhibits rhythmic physiological behaviors, with fluctuations in osmotic pressure and hydration levels that synchronized with the diurnal cycle of activity and rest. Over recent decades, advanced molecular biology techniques have shed light on the association between circadian molecules and IVD homeostasis. The complex interplay between circadian rhythm disruption and IVDD is becoming increasingly evident, with the sympathetic nervous system (SNS) emerging as a potential mediator. Synchronized with circadian rhythm through suprachiasmatic nucleus, the SNS regulates diverse physiological functions and metabolic processes, profoundly influences the structural and functional integrity of the IVD. This review synthesizes the current understanding of circadian regulation and sympathetic innervation of the IVD, highlighting advancements in the comprehension of their interactions. We elucidate the impact of circadian system on the physiological functions of IVD through the SNS, advocating for the adoption of chronotherapy as a brand-new and effective strategy to ameliorate IVDD and alleviate LBP.

Time of day dependent reduction in stroke infarct volume by the Reverb agonist SR9009 in mice

Ischemic stroke leads to disability and death worldwide and evidence suggests that stroke severity is affected by the time dimension of the stroke. Rev-Erbα regulates the core circadian clock through repression of the positive clock element Bmal1. However, it remains unclear if a Rev-Erbα agonist (SR9009) alleviates stroke pathology in mice. We found that stroke reduces the level of Rev-Erbα and elevates neuroinflammation and stroke severity at zeitgeber time (ZT) ZT06. Therefore, we hypothesized that SR9009 treatment may reduce neuroinflammation and stroke severity in a mouse suture occlusion model. At 12 to 14 weeks, C57BL/6 J (Wild Type, n = 5-10 mice/group) mice were randomly assigned to undergo MCAO stroke for 60 min at either zeitgeber time ZT06 (MCAO-ZT06-sleep phase) or ZT18 (MCAO-ZT18-awake phase). Stroked mice were treated with SR9009 (100 mg/kg) or vehicle at 1 h and 24 h after MCAO. After forty-eight hours of stroke, TTC staining, Western blot, and qRT-PCR were performed. We found that SR9009 treatment alleviates neuroinflammation and infarct volume by Rev-Erb remodeling in ZT06 stroke mice but not in ZT18 stroke mice. Additionally, monocytic and neutrophilic NLRP3 as well as brain NLRP3 levels were reduced by SR9009 treatment in ZT06 stroke though no effects were observed at ZT18 stroke. SR9009 also reduced TNFα expression and increased IL-10 expression in blood and brain in ZT06 stroke mice and no differences were observed at ZT18. There were no significant effects of SR9009 on neurological deficit score and sensorimotor function at ZT06 or ZT18 at 48 h. Our study demonstrates that SR9009 treatment reduces stroke volume, circulating immune response, circadian expression, and that the protection was circadian- and treatment time-dependent.

The impact of circadian rhythms on retinal immunity

The eye is an immune-protected organ, which is driven by factors such as cytokines, chemicals, light, and mechanical stimuli. The circadian clock is an intrinsic timing mechanism that influences the immune activities, such as immune cell count and activity, as well as inflammatory responses. Recent studies have demonstrated that the eye also possesses an intrinsic circadian rhythm, and this rhythmic regulation participates in ocular immune modulation. In this review, we discuss the immunoregulatory mechanisms of the circadian clock within the eye, and reveal new perspectives for the prevention and treatment of ocular diseases.

Treatment of acute pharyngitis in rats with season tea decoctions from traditional Chinese medicine through a synergistic and subtle regulation of ARNTL and BHLHE40

ETHNOPHARMACOLOGICAL RELEVANCE

While the seasonal variations in the human immune function and many infectious diseases are well-known, to develop therapeutic strategies regarding such seasonality is quite challenging. However, some traditional medical practices have already taken the seasonality into account, such as the "Season Tea" (ST) decoctions investigated in the present study.

AIM OF THE STUDY

We present a study of the ST decoctions from traditional Chinese medicine, which include four formulae designed for the four seasons, aiming to investigate their pharmacological commonality and distinction.

MATERIALS AND METHODS

A rat model of acute pharyngitis was utilized for the pharmacological study, and the effects of the ST decoctions were evaluated through histology, biomedical assays, microarray analysis, real-time quantitative PCR and Western blot.

RESULTS

The experimental data show that all of the four ST formulae display good pharmaceutical effects on acute pharyngitis, and circadian rhythm appears to be a significant pathway for investigating their pharmacological commonality and distinction. Specifically, while all of the four ST decoctions can regulate the circadian-rhythm-related genes ARNTL and BHLHE40, the regulation is along different directions with the modification of the supplements and the substrates in each ST formula.

CONCLUSION

These results indicate the correlation between the acute pharyngitis and circadian rhythm, and illustrate the possibility of synergistically and subtly regulating ARNTL and BHLHE40, which is significant for relevant drug development.

Signaling pathway mechanisms of circadian clock gene Bmal1 regulating bone and cartilage metabolism: a review

Circadian rhythm is ubiquitous in nature. Circadian clock genes such as Bmal1 and Clock form a multi-level transcription-translation feedback network, and regulate a variety of physiological and pathological processes, including bone and cartilage metabolism. Deletion of the core clock gene Bmal1 leads to pathological bone alterations, while the phenotypes are not consistent. Studies have shown that multiple signaling pathways are involved in the process of Bmal1 regulating bone and cartilage metabolism, but the exact regulatory mechanisms remain unclear. This paper reviews the signaling pathways by which Bmal1 regulates bone/cartilage metabolism, the upstream regulatory factors that control Bmal1, and the current Bmal1 knockout mouse models for research. We hope to provide new insights for the prevention and treatment of bone/cartilage diseases related to circadian rhythms.

Immune regulation of host energy metabolism and periodicity of malaria parasites

The synchronization of Plasmodium parasites as they replicate within red blood cells of their vertebrate host remains largely unexplored. Understanding this synchronization could reveal how parasites optimize their lifecycle to maximize transmission, evade the immune response and maximize energy acquisition. Rhythmic replication fulfils some criteria of an endogenous oscillator with time of day cues potentially provided by temperature, oxygen levels, hormones and/or nutrient availability. Recent research on a rodent malaria model has highlighted that rhythms associated with the host's feeding/fasting cycle are a crucial factor influencing the synchronization of the erythrocytic stages of Plasmodium to the host's circadian cycle. Innate immune responses are also rhythmic and can regulate host metabolism, suggesting that the innate immune response triggered by Plasmodium contributes to its rhythmic replication. Here, we outline how the interplay between immune responses and metabolism could influence the timing and synchronization of Plasmodium's replication rhythm, focusing on the roles of the cytokine tumour necrosis factor, mitochondrial function and metabolites generated by the tricarboxylic acid cycle in highly activated monocytes. These processes are pivotal in controlling parasitemia and determining disease outcome, suggesting that a better understanding of energy metabolism on rhythmic host-parasite interactions may provide new insights for therapeutic interventions against malaria.This article is part of the Theo Murphy meeting issue 'Circadian rhythms in infection and immunity'.

Neuroscience of cancer: unraveling the complex interplay between the nervous system, the tumor and the tumor immune microenvironment

The study of the multifaceted interactions between neuroscience and cancer is an emerging field with significant implications for understanding tumor biology and the innovation in therapeutic approaches. Increasing evidence suggests that neurological functions are connected with tumorigenesis. In particular, the peripheral and central nervous systems, synapse, neurotransmitters, and neurotrophins affect tumor progression and metastasis through various regulatory approaches and the tumor immune microenvironment. In this review, we summarized the neurological functions that affect tumorigenesis and metastasis, which are controlled by the central and peripheral nervous systems. We also explored the roles of neurotransmitters and neurotrophins in cancer progression. Moreover, we examined the interplay between the nervous system and the tumor immune microenvironment. We have also identified drugs that target the nervous system for cancer treatment. In this review we present the work supporting that therapeutic agent targeting the nervous system could have significant potential to improve cancer therapy.

Chronic artificial light exposure in daytime and reversed light: Dark cycle inhibit anti-apoptotic cytokines and defect Bcl-2 in peripheral lymphoid tissues during acute systemic inflammatory response to lipopolysaccharide

AIMS

The disturbed light: dark (LD) cycle has been associated with critical complications, including obesity, diabetes and cancer. In the present study, we investigated the chronic effects of artificial light at daytime (AL) and light at night (RAL) after intraperitoneal (i.p.) injection of saline and 0.5 mg/kg lipopolysaccharide (LPS) in male Wistar rats.

METHODS

Liver and kidney parameters, fasting blood glucose (FBG), melatonin level, immunohistochemical examinations of B-cell lymphoma-2 (Bcl-2) in spleen and mesenteric lymph and serum antiapoptotic cytokines [interleukin (IL-) 2, 7 and 1].

KEY FINDINGS

After 16 weeks of a daily disturbed LD cycle, RAL increased body weight, upgraded FBG and altered liver and kidney functions with surprisingly increased daytime plasma melatonin. AL + LPS and RAL + LPS rats suffered significantly higher oxidative-nitrosative stress compared to NL + LPS. Oxidative-nitrosative stress was associated with multi-organ inflammation in hepatic, renal, pancreatic, splenic and mesenteric lymph node tissues due to LPS-induced endotoxemia. Anti-apoptotic Bcl-2 activity in peripheral lymphoid organs (spleen and mesenteric lymph node) was lowered due to AL and RAL regimens. At the same pattern, lowering of antiapoptotic serum levels of IL-2, IL-7 and IL-15 indicate alteration of cell cycle and the shifted ability of cells to undergo apoptosis due to abnormal light pollution.

SIGNIFICANCE

Here, the increased lymphocyte apoptosis in lymphoid tissues due to disturbed LD cycle defects the host defense, dysregulates the inflammatory immune response and dysregulates the immune tolerance during acute systemic inflammation due to LPS.

Late Bedtime and Altered Diurnal Axial Length Rhythms of the Eye

PURPOSE

Affecting one-third of the population worldwide and increasing, the sight-threatening condition myopia is causing a significant socio-economic burden. To better understand its etiology, recent studies investigated the role of ocular and systemic rhythms, yet results are conflicting. Here we profiled 24-h variations of axial length of the eye and salivary melatonin concentration in young adults with and without myopia and explored the potential impacts of bedtime on these rhythms.

METHODS

A total of 25 healthy young adults (age 25.0 ± 4.8 years, 13 females) completed this study, including 13 myopes (mean spherical equivalent refractive error -2.93 ± 1.46 diopters) and 12 non-myopes (0.14 ± 0.42 diopters). Saliva sample collection and axial length measurements were repeated for seven times over 24 h starting from 8 am. Information on sleep and chronotype was collected at first visit with the Pittsburgh Sleep Quality Index and the Morningness-Eveningness Questionnaire.

RESULTS

Significant diurnal rhythms of axial length and salivary melatonin concentration were identified in both refractive groups (both p < 0.001), with no myopia-related rhythm difference (interaction of measurement time-point × myopia, p = 0.9). Late bedtime was associated with altered rhythms (p = 0.009) and smaller diurnal change (p = 0.01) in axial length. Elevated melatonin levels were observed in myopes (p = 0.006) and in late sleepers (p = 0.017).

CONCLUSIONS

These findings suggest that sleep/wake cycles may be involved in the regulation of axial length rhythms. Further research is needed to determine if there exists a causal relationship between the two.

Clockwork conditioning: Aligning the skeletal muscle clock with time-of-day exercise for cardiometabolic health

Circadian rhythms have evolved to synchronize gene expression, physiology, and behavior with time-of-day changes in the external environment. In every mammalian cell exists a core clock mechanism that consists of a transcriptional-translational feedback loop that drives rhythmic gene expression. Circadian disruption, as observed in shift workers and genetic mouse models, contributes to the onset and progression of cardiometabolic disorders. The central clock, located in the hypothalamus, is uniquely sensitive to external light cues, while the peripheral clocks are responsive to non-photic stimuli such as feeding and activity in addition to signals from the central clock. Recent research has illustrated the sensitivity of the skeletal muscle circadian clock to exercise timing, offering a promising avenue for therapeutic intervention in cardiometabolic health. Here we provide an in-depth examination of the molecular mechanisms underlying skeletal muscle clock function and its impact on cardiometabolic pathways, including glucose and lipid metabolism, as well as inflammation. To highlight the role of exercise as a time-cue for the skeletal muscle clock, we discuss evidence of exercise-induced shifts in the skeletal muscle clock and the differential response to exercise performed at different times of the day. Furthermore, we present data in support of time-of-day exercise as a potential therapeutic strategy for mitigating cardiometabolic disease burden. By exploring the relationship between the skeletal muscle clock, exercise timing, and cardiometabolic health, we identify new areas for future research and offer valuable insights into novel therapeutic approaches aimed at improving cardiometabolic disease outcomes.

Circadian Rhythms Correlated in DNA Methylation and Gene Expression Identified in Human Blood and Implicated in Psychiatric Disorders

Circadian rhythms modulate the biology of many human tissues and are driven by a nearly 24-h transcriptional feedback loop. Dynamic DNA methylation may play a role in driving 24-h rhythms of gene expression in the human brain. However, little is known about the degree of circadian regulation between the DNA methylation and the gene expression in the peripheral tissues, including human blood. We hypothesized that 24-h rhythms of DNA methylation play a role in driving 24-h RNA expression in human blood. To test this hypothesis, we analyzed DNA methylation levels and RNA expression in blood samples collected from eight healthy males at six-time points over 24 h. We assessed 442,703 genome-wide CpG sites in methylation and 12,364 genes in expression for 24-h rhythmicity using the cosine model. Our analysis revealed significant rhythmic patterns in 6345 CpG sites and 21 genes. Next, we investigated the relationship between methylation and expression using powerful circadian signals. We found a modest negative correlation (ρ = -0.83, p = 0.06) between the expression of gene TXNDC5 and the methylation at the nearby CpG site (cg19116172). We also observed that circadian CpGs significantly overlapped with genetic risk loci of schizophrenia and autism spectrum disorders. Notably, one gene, TXNDC5, showed a significant correlation between circadian methylation and expression and has been reported to be association with neuropsychiatric diseases.

Time-restricted feeding modulates gene expression related with rhythm and inflammation in Mongolian gerbils

Time-restricted feeding (TRF) has the potential to modulate circadian rhythm and widely studied in humans and laboratory mice. However, less is known about the physiological responses to TRF in wild mammals. Here, we used Mongolian gerbils, Meriones unguiculatus, to explore the effect of 6-week TRF on gene expression related with circadian rhythm and inflammation. The TRF gerbils had higher cumulative food intake than the ad libitum (AL) group, but body mass, feeding frequency/time and metabolic rate did not differ between groups. In the hypothalamus, downregulation of rhythm-related genes Per3, Cry1 and Dbp was detected in the daytime-restricted feeding (DRF) group and Cry1 was downregulated in the nighttime-restricted feeding (NRF) group. In the liver, the expression of Per1/3, Rev-erbα/β and Dbp was lower, and Bmal1 was higher in the DRF than in AL group, while NRF gerbils showed no changes. In the colon, the expression of Bmal1 and Cry1 was higher but Per3, Rev-erbα/β and Dbp were lower in the DRF than in AL group. Further, the expression of inflammation-related genes such as NF-κB, IL-1β, IL-18 and Nlrp3 was lower in the liver of DRF gerbils, and IL-1β was lower both in the hypothalamus and liver of NRF gerbils. Moreover, the genes related with inflammation such as NF-κB, Nlrp3, IL-10/18/1β and Tnf-α were positively or negatively correlated with multiple rhythm-related genes in the central and peripheral organs. In conclusion, TRF, particularly DRF, could modulate rhythm-related genes in the central and peripheral tissues and reduce hepatic expression of inflammation-related genes in gerbils.

NR1D1exon6::MAML2exon2 Fusion-Positive Sarcomas: Two Additional Cases of an Emerging Soft Tissue Tumor Entity

NR1D1::MAML1/L2 fusion-positive sarcomas constitute an emerging subtype of undifferentiated sarcomas, histopathologically composed of epithelioid and spindle cells. We describe two NR1D1exon6::MAML2exon2 fusion-positive sarcomas occurring in the occipital region of a 53-year-old female patient and the left shoulder of a 25-year-old male patient. Histopathologically, the former tumor comprised spindle and polygonal-shaped/epithelioid cells, while the latter comprised epithelioid cells. Immunohistochemically, the cells of the first tumor were positive for keratin cocktail (AE1/AE3), EMA, and p40. The other tumor lacked any epithelial marker immunoexpression and showed SATB2 positivity. Both the tumors were SMARCB1 proficient. While the former tumor was initially diagnosed as a sarcomatoid carcinoma, the latter was diagnosed as an undifferentiated sarcoma.Both patients underwent surgical resection as the primary treatment. One patient received adjuvant radiotherapy, whereas the other received ifosfamide and doxorubicin-based therapy. However, both the patients developed progressive disease, with one developing lung metastasis during relapse. There was a suboptimal response to chemotherapy in both patients.This study highlights the clinicopathological features of two rare and emerging sarcomas. It further emphasizes the value of high-throughput molecular testing, such as next-generation sequencing in the undifferentiated epithelioid, and spindle-cell sarcomas to identify the prognostic subtypes and differentiate these neoplasms from their histopathological mimics.

Differential serum levels of CACNA1C, circadian rhythm and stress response molecules in subjects with bipolar disorder: Associations with genetic and clinical factors

BACKGROUND

Many patients with bipolar disorder (BD) do not respond to or have difficulties tolerating lithium and/or other mood stabilizing agents. There is a need for personalized treatments based on biomarkers in guiding treatment options. The calcium voltage-gated channel CACNA1C is a promising candidate for developing personalized treatments. CACNA1C is implicated in BD by genome-wide association studies and several lines of evidence suggest that targeting L-type calcium channels could be an effective treatment strategy. However, before such individualized treatments can be pursued, biomarkers predicting treatment response need to be developed.

METHODS

As a first step in testing the hypothesis that CACNA1C genotype is associated with serum levels of CACNA1C, we conducted ELISA measures on serum samples from 100 subjects with BD and 100 control subjects.

RESULTS

We observed significantly higher CACNA1C (p < 0.01) protein levels in subjects with BD. The risk single nucleotide polymorpshism (SNP) (rs11062170) showed functional significance as subjects homozygous for the risk allele (CC) had significantly greater CACNA1C protein levels compared to subjects with one (p = 0.013) or no copies (p = 0.009). We observed higher somatostatin (SST) (p < 0.003) protein levels and lower levels of the clock protein aryl hydrocarbon receptor nuclear translocator-like (ARTNL) (p < 0.03) and stress signaling factor corticotrophin releasing hormone (CRH) (p < 0.001) in BD. SST and period 2 (PER2) protein levels were associated with both alcohol dependence and lithium response.

CONCLUSIONS

Our findings represent the first evidence for increased serum levels of CACNA1C in BD. Along with altered levels of SST, ARNTL, and CRH our findings suggest CACNA1C is associated with circadian rhythm and stress response disturbances in BD.

Circadian Rhythms of Skin Surface Lipids and Physiological Parameters in Healthy Chinese Women Reveals Circadian Changes in Skin Barrier Function

BACKGROUND

Circadian rhythms are driven by the biological clock, an endogenous oscillator that generates approximately 24 h cycles in mammals. The circadian regulation of the lipid metabolism plays a crucial role in overall metabolic health. An analysis of the correlation between the skin's physiological parameters and skin lipids can provide a better insight into the rhythmic changes in skin condition.

OBJECTIVES

The aim was to reveal how skin surface lipids (SSLs) participate in the regulation of circadian rhythms in the skin and the importance of the circadian oscillation of facial lipid molecules in maintaining epidermal homeostasis.

METHODS

Changes in SSLs were assessed using UPLC-QTOF-MS. The skin's physiological parameters were quantified using non-invasive instruments. Multivariate data analysis was employed to evaluate the differences.

RESULTS

Both skin surface lipids and physiological parameters exhibited certain circadian variation patterns. Four major lipid classes (fatty acids, glycerophospholipids, prenol lipids, saccharolipids) exhibited circadian rhythmic trends, with seven lipid subclasses contributing most significantly to the overall patterns observed. Among the physiological parameters assessed, sebum secretion, transepidermal water loss, moisture measurement value, and skin surface temperature exhibited sinusoidal circadian rhythms. Further analysis revealed significant correlations between fatty acids and saccharolipids with moisture measurement values, and between glycerolipids and pH value. In addition, lipids closely associated with the barrier such as unsaturated fatty acids and ceramide chain lengths correlated significantly with moisture measurement values.

CONCLUSIONS

Through correlation analysis, the study elucidates the influence of diurnal fluctuations in skin surface lipids on skin barrier function. These findings hold significant implications for understanding skin barrier impairment associated with circadian rhythm disruptions.

Nuclear receptor Rev-erbα alleviates intervertebral disc degeneration by recruiting NCoR-HDAC3 co-repressor and inhibiting NLRP3 inflammasome

Intervertebral discs (IVDs) are rhythmic tissues that experience daily low-load recovery. Notably, aging and abnormal mechanical stress predispose IVDs to degeneration due to dysrhythmia-induced disordered metabolism. Meanwhile, Rev-erbα acts as a transcriptional repressor in maintaining biorhythms and homeostasis; however, its function in IVD homeostasis and degeneration remains unclear. This study assessed the relationship between low Rev-erbα expression levels and IVD degeneration. Rev-erbα deficiency accelerated needle puncture or aging-induced IVD degeneration, characterized by increased extracellular matrix (ECM) catabolism and nucleus pulposus (NP) cell apoptosis. Mechanistically, Rev-erbα knockdown in NP cells aggravated rhIL1β-induced NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activation, exacerbating the imbalanced ECM and NP cell apoptosis. Meanwhile, blocking NLRP3 inflammasome activation mitigated Rev-erbα deficiency and needle puncture-induced IVD degeneration. Particularly, Rev-erbα mediated the transcriptional repression of the NLRP3 inflammasome via the ligand heme-binding of nuclear receptor co-repressor (NCoR) and histone deacetylase 3 (HDAC3) complex. Thus, the increased expression of Rev-erbα in NP cells following short-term rhIL1β treatment failed to inhibit NLRP3 transcription in vitro owing to heme depletion. Pharmacological activation of Rev-erbα in vivo and in vitro alleviated IVD degeneration by altering the NLRP3 inflammasome. Taken together, targeting Rev-erbα may be a potential therapeutic strategy for alleviating IVD degeneration and its related diseases.

Circadian rhythms in haematological malignancies: therapeutic potential and personalised interventions

The circadian clock, a fundamental cellular mechanism, regulates the rhythmic expression of numerous genes and biological processes across various organs. Disruptions in this system, driven by genetic or environmental factors, have been reported to be involved in cancer progression. This review explores the role of the circadian clock in cancer hallmarks and its impact on cellular homeostasis within haematological malignancies. Drawing on findings from in vitro, in vivo, and clinical trials, this review highlights the potential of clock genes as diagnostic and prognostic biomarkers, and as therapeutic targets for optimising treatment timing. It discusses how circadian rhythms can enhance treatment efficacy through both pharmacological and non-pharmacological interventions, outlining strategies for optimising dosing schedules and implementing personalised chronobiological interventions, with a particular focus on haematological malignancies, including cutaneous lymphoma. Ongoing research holds promise for advancing personalised therapeutic approaches and ultimately improving cancer care standards.

The diurnal pattern of cytokines, chemokines and growth factors in human saliva-a pilot study

Background

Understanding of possible periodicity of cytokines, chemokines and growth factors is of great interest and provide valuable information for research into pathophysiological mechanism of inflammatory disease and chronic pain. Significant efforts have been made to identify different analytes in saliva. For precision and accuracy in measurement and interpretation of results, it is crucial to know the source of variability, especially the circadian variation for the analytes.

Objective

The study aimed to analyze circadian variation in 71 inflammatory markers in both unstimulated and stimulated saliva, as well as plasma, from a sample of healthy individuals.

Methods

Ten young adults participated. Unstimulated and stimulated whole saliva were collected at 3-h intervals between between 7:30 am and 7:30 pm. Blood samples were drawn in connection with the first and last saliva collection. All samples were analyzed using the U-PLEX 71-Plex assay.

Results

The analysis showed distinct clustering of the 71 inflammatory mediators between plasma and saliva. Furthermore, differences were also observed between stimulated and unstimulated saliva. The proteins were clustered into three groups that expressed different circadian rhythms. These clusters were stable over time in stimulated saliva but showed significant variability in unstimulated saliva (P < 0.05).

Conclusions

These results suggest that time of the day could influence the detection and interpretation of inflammatory markers and collecting saliva samples at consistent times across participants will help control for the natural fluctuations in salivary composition. The results encourage further exploration of salivary diagnostics, particularly in understanding circadian rhythms and localized immune responses.

Targeting immune cell recruitment in atherosclerosis

Atherosclerosis is the primary underlying cause of myocardial infarction and stroke. Atherosclerotic cardiovascular disease is characterized by a chronic inflammatory reaction in medium-to-large-sized arteries, with its onset and perpetuation driven by leukocytes infiltrating the subendothelial space. Activation of endothelial cells triggered by hyperlipidaemia and lipoprotein retention in the arterial intima initiates the accumulation of pro-inflammatory leukocytes in the arterial wall, fostering the progression of atherosclerosis. This inflammatory response is coordinated by an array of soluble mediators, namely cytokines and chemokines, that amplify inflammation both locally and systemically and are complemented by tissue-specific molecules that regulate the homing, adhesion and transmigration of leukocytes. Despite abundant evidence from mouse models, only a few therapies targeting leukocytes in atherosclerosis have been assessed in humans. The major challenges for the clinical translation of these therapies include the lack of tissue specificity and insufficient selectivity of inhibition strategies. In this Review, we discuss the latest research on receptor-ligand pairs and interactors that regulate leukocyte influx into the inflamed artery wall, primarily focusing on studies that used pharmacological interventions. We also discuss mechanisms that promote the resolution of inflammation and highlight how major findings from these research areas hold promise as potential therapeutic strategies for atherosclerotic cardiovascular disease.

Influence of Acute Inflammation on the Expression of Clock Genes in the Ovine Pars Tuberalis Under Different Photoperiodic Conditions

The pars tuberalis (PT) plays an important role in the photoperiodic regulation of the secretory activity of the pituitary gland. Additionally, PT secretory activity may be influenced by the animal's immune status. The melatonin signal processing in PT cells occurs through the presence of melatonin receptors and the expression of molecular clock genes. This study aimed to define the effects of acute inflammation induced by intravenous administration of lipopolysaccharide (LPS) on the expression of clock genes in the PT of ewes under different photoperiodic conditions. Two analogous experiments were conducted in different photoperiods: short-day and long-day. Both experiments included 24 sheep divided into two groups: day (n = 12) and night (n = 12), further subdivided into a control group (n = 6) and a group treated with LPS (n = 6) at a dose of 400 ng/kg. Under short-day conditions, the expression of clock circadian regulator, basic helix-loop-helix ARNT like 1, cryptochrome circadian regulator (CRY) 1, 2, and casein kinase 1 epsilon genes was lower during inflammation. LPS injection increased expression of the period circadian regulator 1 gene during the night. Under long-day conditions, CRY1 mRNA level was lower during the night, while diurnal CRY2 mRNA expression was decreased after LPS injection. Our results showed that inflammation disturbed the expression of molecular clock genes in the PT; however, this influence was partly dependent on photoperiod conditions.

Bidirectional Interaction of Sepsis and Sleep Disorders: The Underlying Mechanisms and Clinical Implications

Sepsis is defined as life-threatening organ injury induced by infection, with high incidence and mortality. Sleep disorder is prevalent in septic patients and approximately 50% of patients with sepsis may develop atypical sleep patterns, but many of them may have been underdiagnosed by physicians. Sleep disorders and sepsis exhibit a close bidirectional relationship, with each condition significantly influencing the other. Conversely, sleep deprivation, sleep dysrhythmia and sleep fragmentation have been shown to impact the outcome of sepsis. This review endeavors to offer a comprehensive understanding of the intricate mechanisms that underpin the interplay between sepsis and sleep disorders, in addition to exploring potential clinical intervention strategies that could enhance outcomes for patients suffering from sepsis.

Brief Disruption of Circadian Rhythms Alters Intestinal Barrier Integrity and Modulates DSS-Induced Colitis Severity in Mice

Physiological processes in organisms exhibit circadian rhythms that optimize fitness and anticipate environmental changes. Luminal signals such as food or metabolites synchronize bowel activity, and disruptions in these rhythms are linked to metabolic disorders and gastrointestinal inflammation. To characterize the intrinsic intestinal rhythms and assess disruptions due to continuous darkness or light exposure, C57BL/6 mice were exposed to standard light-dark conditions or continuous light/darkness for 48 h, with evaluations at four timepoints. We assessed intestinal morphology, mucus production, nitric oxide levels and permeability. Under standard light: dark cycles, mice showed changes in intestinal morphology consistent with normal tract physiology. Continuous light exposure caused marked alterations in the small intestine´s epithelium and lamina propria, reduced nitric oxide production in the colon, and predominant neutral mucins. Enhanced permeability was indicated by higher FITC-dextran uptake and increased frequency of IgG-coated bacteria. Additionally, the 48 h-disruption influenced DSS-induced colitis with attenuation in L:L group, or exacerbation in D:D group, of clinical signs. These findings highlight the critical role of circadian rhythms in gut histoarchitecture and function, demonstrating that short-term disruptions in light-dark cycles can compromise intestinal barrier integrity and impact inflammatory outcomes.

Uncovering the impact and mechanisms of air pollution on eye and ear health in China

Increasing air pollution could undermine human health, but the causal link between air pollution and eye and ear health has not been well-studied. Based on four-week-level records of eye and ear health over 1991-2015 provided by the China Health and Nutrition Survey, we estimate the causal effect of air pollution on eye and ear health. Using two-stage least squares estimation, we find that eye or ear disease possibility rises 1.48% for a 10 μg/m3 increase in four-week average PM2.5 concentration. The impacts can last about 28 weeks and will be insignificant afterward. Females, individuals aged 60 years and over, with high exposure environments, relatively poor economic foundations, and low knowledge levels are more vulnerable to such negative influences. Behavioral channels like more smoking activities and less sleeping activities could partly explain this detrimental effect. Our findings enlighten how to minimize the impact of air pollution and protect public health.

The Effects of STRA6 Regulation of the Circadian Rhythm on Choroidal Neovascularization

Purpose

This study aims to investigate the relationship among STRA6, circadian rhythm, and choroidal neovascularization (CNV) formation, as well as the regulatory mechanism of STRA6 in CNV under circadian rhythm disturbances.

Methods

C57BL/6J male mice (aged 6 weeks) were randomly divided into control and jet lag groups (using a time shift method every 4 days to disrupt the molecular clock's capacity to synchronize with a stable rhythm). A laser-induced CNV model was established in both the control and the jet lag group after 2 weeks of jet lag. The size of CNV lesions and vascular leakage were detected by morphological and imaging examination on the seventh day post laser. STRA6 was screened by full transcriptome sequencing. Bioinformatics analysis was conducted to assess the variation and association of STRA6 in the GSE29801 dataset. The effects of STRA6 were evaluated both in vivo and in vitro. The pathway mechanism was further elucidated and confirmed through immunofluorescence of paraffin sections and Western blotting.

Results

The disturbance of circadian rhythm promotes the formation of CNV. Patients with age-related macular degeneration (AMD) exhibited higher levels of STRA6 expression compared to the control group, and STRA6 was enriched in pathways related to angiogenesis. In addition, CLOCK and BMAL1, which are initiators that drive the circadian cycle, had regulatory effects on STRA6. Knocking down STRA6 reversed the promotion of CNV formation caused by circadian rhythm disturbance in vivo, and it also affected the proliferation, migration, and VEGF secretion of RPE cells without circadian rhythm in vitro, as well as impacting endothelial cells. Through activation of the JAK2/STAT3/VEGFA signaling pathway in unsynchronized RPE cells, STRA6 promotes CNV formation.

Conclusions

This study suggests that STRA6 reduces CNV production by inhibiting JAK2/STAT3 phosphorylation after circadian rhythm disturbance. The results suggest that STRA6 may be a new direction for the treatment of AMD.

Ticking Brain: Circadian Rhythm as a New Target for Cerebroprotection

Circadian rhythm is a master process observed in nearly every type of cell throughout the body, and it macroscopically regulates daily physiology. Recent clinical trials have revealed the effects of circadian variation on the incidence, pathophysiological processes, and prognosis of acute ischemic stroke. Furthermore, core clock genes, the cell-autonomous pacemakers of the circadian rhythm, affect the neurovascular unit-composing cells in a nonparallel manner after the same pathophysiological processes of ischemia/reperfusion. In this review, we discuss the influence of circadian rhythms and clock genes on each type of neurovascular unit cell in the pathophysiological processes of acute ischemic stroke.

E3 ubiquitin ligase UBR5 modulates circadian rhythm by facilitating the ubiquitination and degradation of the key clock transcription factor BMAL1

The circadian clock is the inner rhythm of life activities and is controlled by a self-sustained and endogenous molecular clock, which maintains a ~ 24 h internal oscillation. As the core element of the circadian clock, BMAL1 is susceptible to degradation through the ubiquitin-proteasome system (UPS). Nevertheless, scant information is available regarding the UPS enzymes that intricately modulate both the stability and transcriptional activity of BMAL1, affecting the cellular circadian rhythm. In this work, we identify and validate UBR5 as a new E3 ubiquitin ligase that interacts with BMAL1 by using affinity purification, mass spectrometry, and biochemical experiments. UBR5 overexpression induced BMAL1 ubiquitination, leading to diminished stability and reduced protein level of BMAL1, thereby attenuating its transcriptional activity. Consistent with this, UBR5 knockdown increases the BMAL1 protein. Domain mapping discloses that the C-terminus of BMAL1 interacts with the N-terminal domains of UBR5. Similarly, cell-line-based experiments discover that HYD, the UBR5 homolog in Drosophila, could interact with and downregulate CYCLE, the BMAL1 homolog in Drosophila. PER2-luciferase bioluminescence real-time reporting assay in a mammalian cell line and behavioral experiments in Drosophila reveal that UBR5 or hyd knockdown significantly reduces the period of the circadian clock. Therefore, our work discovers a new ubiquitin ligase UBR5 that regulates BMAL1 stability and circadian rhythm and elucidates the underlying molecular mechanism. This work provides an additional layer of complexity to the regulatory network of the circadian clock at the post-translational modification level, offering potential insights into the modulation of the dysregulated circadian rhythm.

BMAL1 plays a crucial role in immune homeostasis during sepsis-induced acute lung injury

Sepsis is a widespread and life-threatening disease characterised by infection-triggered immune hyperactivation and cytokine storms, culminating in tissue damage and multiple organ dysfunction syndrome. BMAL1 is a pivotal transcription factor in the circadian clock that plays a crucial role in maintaining immune homeostasis. BMAL1 dysregulation has been implicated in inflammatory diseases and immunodeficiency. However, the mechanisms underlying BMAL1 disruption in sepsis-induced acute lung injury (ALI) remain poorly understood. In vitro, we used THP1 and mouse peritoneal macrophages to elucidate the potential mechanism of BMAL1 function in sepsis. In vivo, an endotoxemia model was used to investigate the effect of BMAL1 on sepsis and the therapeutic role of targeting CXCR2. We showed that BMAL1 significantly affected the regulation of innate immunity in sepsis-induced ALI. BMAL1 deficiency in the macrophages exacerbated systemic inflammation and sepsis-induced ALI. Mechanistically, BMAL1 acted as a transcriptional suppressor and regulated the expression of CXCL2. BMAL1 deficiency in macrophages upregulated CXCL2 expression, increasing the recruitment of polymorphonuclear neutrophils and the formation of neutrophil extracellular traps (NETs) by binding to the chemokine receptor CXCR2, thereby intensifying lung injury in a sepsis model. Furthermore, a selective inhibitor of CXCR2, SB225002, exerted promising therapeutic effects by markedly reducing neutrophil infiltration and NETs formation and alleviating lung injury. Importantly, CXCR2 blockade mitigated multiple organ dysfunction. Collectively, these findings suggest that BMAL1 controls the CXCL2/CXCR2 pathway, and the therapeutic efficacy of targeting CXCR2 in sepsis has been validated, presenting BMAL1 as a potential therapeutic target for lethal infections.

Towards the discovery of novel molecular clocks in Prokaryotes

Diel cycle is of enormous biological importance as it imposes daily oscillation in environmental conditions, which temporally structures most ecosystems. Organisms developed biological time-keeping mechanisms - circadian clocks - that provide a significant fitness advantage over competitors by optimising the synchronisation of their biological activities. While circadian clocks are ubiquitous in Eukaryotes, they are so far only characterised in Cyanobacteria within Prokaryotes. However, growing evidence suggests that circadian clocks are widespread in the bacterial and archaeal domains. As Prokaryotes are at the heart of crucial environmental processes and are essential to human health, unravelling their time-keeping systems provides numerous applications in medical research, environmental sciences, and biotechnology. In this review, we elaborate on how novel circadian clocks in Prokaryotes offer research and development perspectives. We compare and contrast the different circadian systems in Cyanobacteria and discuss about their evolution and taxonomic distribution. We necessarily provide an updated phylogenetic analysis of bacterial and archaeal species that harbour homologs of the main cyanobacterial clock components. Finally, we elaborate on new potential clock-controlled microorganisms that represent opportunities of ecological and industrial relevance in prokaryotic groups such as anoxygenic photosynthetic bacteria, methanogenic archaea, methanotrophs or sulphate-reducing bacteria.

Morphologic, cytometric, quantitative transcriptomic and functional characterisation provide insights into the haemocyte immune responses of Pacific abalone (Haliotis discus hannai)

In recent years, the abalone aquaculture industry has been threatened by the bacterial pathogens. The immune responses mechanisms underlying the phagocytosis of haemocytes remain unclear in Haliotis discus hannai. It is necessary to investigate the immune mechanism in response to these bacterial pathogens challenges. In this study, the phagocytic activities of haemocytes in H. discus hannai were examined by flow cytometry combined with electron microscopy and transcriptomic analyses. The results of Vibrio parahaemolyticus, Vibrio alginolyticus and Staphylococcus aureu challenge using electron microscopy showed a process during phagosome formation in haemocytes. The phagocytic rate (PP) of S. aureus was higher than the other five foreign particles, which was about 63%. The PP of Vibrio harveyi was about 43%, the PP peak of V. alginolyticus in haemocyte was 63.7% at 1.5 h. After V. parahaemolyticus and V. alginolyticus challenge, acid phosphatase, alkaline phosphatase, total superoxide dismutase, lysozyme, total antioxidant capacity, catalase, nitric oxide synthase and glutathione peroxidase activities in haemocytes were measured at different times, differentially expressed genes (DEGs) were identified by quantitative transcriptomic analysis. The identified DEGs after V. parahaemolyticus challenge included haemagglutinin/amebocyte aggregation factor-like, supervillin-like isoform X4, calmodulin-like and kyphoscoliosis peptidase-like; the identified DEGs after V. alginolyticus challenge included interleukin-6 receptor subunit beta-like, protein turtle homolog B-like, rho GTPase-activating protein 6-like isoform X2, leukocyte surface antigen CD53-like, calponin-1-like, calmodulin-like, troponin C, troponin I-like isoform X4, troponin T-like isoform X18, tumor necrosis factor ligand superfamily member 10-like, rho-related protein racA-like and haemagglutinin/amebocyte aggregation factor-like. Some immune-related KEGG pathways were significantly up-regulated or down-regulated after challenge, including thyroid hormone synthesis, Th17 cell differentiation signalling pathway, focal adhesion, melanogenesis, leukocyte transendothelial migration, inflammatory mediator regulation of TRP channels, ras signalling pathway, rap1 signalling pathway. This study is the first step towards understanding the H. discus hannai immune system by adapting several tools to gastropods and providing a first detailed morpho-functional study of their haemocytes.

Dim light at night shifts microglia to a pro-inflammatory state after cerebral ischemia, altering stroke outcome in mice

Circadian rhythms are endogenous biological cycles that regulate physiology and behavior and are set to precisely 24-h by light exposure. Light at night (LAN) dysregulates physiology and function including immune response; a critical component that contributes to stroke pathophysiological progression of neuronal injury and may impair recovery from injury. The goal of this study is to explore the effects of dim LAN (dLAN) in a murine model of ischemic stroke to assess how nighttime lighting from hospital settings can affect stroke outcome. Further, this study sought to identify mechanisms underlying pathophysiological changes to immune response after circadian disruption. Male and female adult Swiss Webster (CFW) mice were subjected to transient or permanent focal cerebral ischemia, then were subsequently placed into either dark night conditions (LD) or one night of dLAN (5 lx). 24 h post-stroke, sensorimotor impairments and infarct sizes were quantified. A single night of dLAN following MCAO increased infarct size and sensorimotor deficits across both sexes and reduced survival in males after 24 h. Flow cytometry was performed to assess microglial phenotypes after MCAO, and revealed that dLAN altered the percentage of microglia that express pro-inflammatory markers (MHC II+ and IL-6) and microglia that express CD206 and IL-10 that likely contributed to poor ischemic outcomes. Following these results, microglia were reduced in the brain using Plexxikon 5622 (PLX 5622) a CSFR1 inhibitor, then the mice received an MCAO and were exposed to LD or dLAN conditions for 24 h. Microglial depletion by PLX5622 resulted in infarct sizes that were comparable between lighting conditions. This study provides supporting evidence that environmental lighting exacerbates ischemic injury and post-stroke mortality by a biological mechanism that exposure to dLAN causes a fundamental shift of activated microglial phenotypes from beneficial to detrimental at an early time point after stroke, resulting in irreversible neuronal death.

Pioneering new frontiers in circadian medicine chronotherapies for cardiovascular health

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

Circadian control of tumor immunosuppression affects efficacy of immune checkpoint blockade

The circadian clock is a critical regulator of immunity, and this circadian control of immune modulation has an essential function in host defense and tumor immunosurveillance. Here we use a single-cell RNA sequencing approach and a genetic model of colorectal cancer to identify clock-dependent changes to the immune landscape that control the abundance of immunosuppressive cells and consequent suppression of cytotoxic CD8+ T cells. Of these immunosuppressive cell types, PD-L1-expressing myeloid-derived suppressor cells (MDSCs) peak in abundance in a rhythmic manner. Disruption of the epithelial cell clock regulates the secretion of cytokines that promote heightened inflammation, recruitment of neutrophils and the subsequent development of MDSCs. We also show that time-of-day anti-PD-L1 delivery is most effective when synchronized with the abundance of immunosuppressive MDSCs. Collectively, these data indicate that circadian gating of tumor immunosuppression informs the timing and efficacy of immune checkpoint inhibitors.

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.

Circadian Variation in the Response to Vaccination: A Systematic Review and Evidence Appraisal

Molecular timing mechanisms known as circadian clocks drive endogenous 24-h rhythmicity in most physiological functions, including innate and adaptive immunity. Consequently, the response to immune challenge such as vaccination might depend on the time of day of exposure. This study assessed whether the time of day of vaccination (TODV) is associated with the subsequent immune and clinical response by conducting a systematic review of previous studies. The Cochrane Library, PubMed, Google, Medline, and Embase were searched for studies that reported TODV and immune and clinical outcomes, yielding 3114 studies, 23 of which met the inclusion criteria. The global severe acute respiratory syndrome coronavirus 2 vaccination program facilitated investigation of TODV and almost half of the studies included reported data collected during the COVID-19 pandemic. There was considerable heterogeneity in the demography of participants and type of vaccine, and most studies were biased by failure to account for immune status prior to vaccination, self-selection of vaccination time, or confounding factors such as sleep, chronotype, and shiftwork. The optimum TODV was concluded to be afternoon (5 studies), morning (5 studies), morning and afternoon (1 study), midday (1 study), and morning or late afternoon (1 study), with the remaining 10 studies reporting no effect. Further research is required to understand the relationship between TODV and subsequent immune outcome and whether any clinical benefit outweighs the potential effect of this intervention on vaccine uptake.