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Haraszti RÁ, Ella K, Gyöngyösi N, Roenneberg T, Káldi K. Social jetlag negatively correlates with academic performance in undergraduates. Chronobiol Int 2014; 31:603-12. [PMID: 24491157 DOI: 10.3109/07420528.2013.879164] [Citation(s) in RCA: 136] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Discrepancies between sleep timing on workdays and weekends, also known as social jetlag (SJL), affect the majority of the population and have been found to be associated with increased health risk and health-impairing behaviors. In this study, we explored the relationship between SJL and academic performance in a sample of undergraduates of the Semmelweis University. We assessed SJL and other sleep-related parameters with the Munich ChronoType Questionnaire (MCTQ) (n = 753). Academic performance was measured by the average grade based on weekly test results as well as scores acquired on the final test (n = 247). The average mid-sleep point on free days in the Hungarian sample fits well the regression line plotted for longitudes within the Central European Time Zone and chronotypes, confirming that sunlight has a major impact on chronotype. Multivariate analysis showed negative effect of SJL on the weekly average grade (p = 0.028, n = 247) during the lecture term with its highly regular teaching schedules, while this association disappeared in the exam period (p = 0.871, n = 247) when students had no scheduled obligations (lower SJL). We also analyzed the relationship between the time of the weekly tests and academic performance and found that students with later sleep times on free days achieved worse in the morning (p = 0.017, n = 129), while the inverse tendency was observed for the afternoon test-takers (p = 0.10, n = 118). We did not find significant association between academic performance and sleep duration or sleep debt on work days. Our data suggest that circadian misalignment can have a significant negative effect on academic performance. One possible reason for this misalignment is socially enforced sleep times.
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Research Support, Non-U.S. Gov't |
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Ella K, Csépányi-Kömi R, Káldi K. Circadian regulation of human peripheral neutrophils. Brain Behav Immun 2016; 57:209-221. [PMID: 27132055 DOI: 10.1016/j.bbi.2016.04.016] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 04/13/2016] [Accepted: 04/26/2016] [Indexed: 01/12/2023] Open
Abstract
Neutrophils are the most abundant leukocytes in human blood. Beside being essential responders in bacterial and fungal infections, they also contribute to tissue reactions in many autoimmune and inflammatory diseases. Although several immune responses linked to neutrophil functions have been described to be rhythmic, the mechanism of the circadian regulation of these cells is still not understood. Characterization of the time-of-day-specific control of neutrophil responsiveness could help to better understand the pathomechanism of these inflammatory responses and design effective chronotherapy. Here we report that the time-dependent expression of core clock components in human neutrophils characteristically differs from that in mononuclear cells. Both the low expression and the reduced nuclear accumulation of the essential clock protein BMAL1 suggest that the molecular oscillator is down-regulated in neutrophils. By following the expression of the maturation marker Cxcr4 and morphological attributes (side-scattering properties and nuclear segmentation), we found that the distribution of young and aged cells within the peripheral neutrophil pool displays a daily rhythm. In addition, we detected synchronous fluctuations in the plasma level of the CXCR4 ligand CXCL12, an important regulator of cell trafficking within the bone marrow. We found that expression of another maturation marker, the core component of the superoxide generating NADPH oxidase, and parallelly, the superoxide producing capacity of neutrophils were also dependent on the time of the day. In line with this, number of opsonized bacteria engulfed by neutrophils also showed time-dependent differences, supporting that clearance of pathogens shows a daily rhythm. We suggest that maturation-dependent changes in neutrophil responsiveness rather than the cellular autonomous clock are involved in the daily regulation of human neutrophil functions.
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Sűdy ÁR, Ella K, Bódizs R, Káldi K. Association of Social Jetlag With Sleep Quality and Autonomic Cardiac Control During Sleep in Young Healthy Men. Front Neurosci 2019; 13:950. [PMID: 31555086 PMCID: PMC6742749 DOI: 10.3389/fnins.2019.00950] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 08/22/2019] [Indexed: 01/23/2023] Open
Abstract
Social jetlag (SJL), the difference in sleep timing between work and free days is a consequence of the discrepancy between the individual’s circadian rhythm and the social clock. SJL is considered a chronic stress factor and has been linked to various health problems. In this field study, we examined for the first time the association between SJL and cardiac regulation during sleep. 33 healthy young men aged 20–26 years participated in the study. The median SJL was used as a cut-off value to assign the participants into two groups with either lower or higher SJL. As a marker of autonomic control we analyzed heart rate variability (HRV) and addressed intra-individual differences between workdays and free days. In subjects with higher SJL, pNN50, an indicator of vagal activity was lower in the first 3 h of sleep on workday as compared to free day (day × sleep block × group, p = 0.015), indicating a more adaptable regulation on free days, when subjects slept according to their own preference. However, in subjects with lower SJL, no HRV differences were found between the two nights. SJL showed correlation with the free day-workday differences of both pNN50 and another vagal index, RMSSD in the first 2 h of sleep (p = 0.023 and 0.047, respectively). In subjects with higher SJL, a different HF power on workdays and free days (p = 0.031) also indicated that a shift in sleep timing is accompanied by an altered parasympathetic activity in the first few hours of sleep. Furthermore, subjective sleep quality on workdays was negatively associated with SJL (p = 0.02), and subjects with higher SJL reported worse sleep quality on workday than on free day (p = 0.027). Taken together, our data call attention on the potential effect of SJL on sleep quality and vagal activity during sleep.
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Gyöngyösi N, Nagy D, Makara K, Ella K, Káldi K. Reactive oxygen species can modulate circadian phase and period in Neurospora crassa. Free Radic Biol Med 2013; 58:134-43. [PMID: 23277144 DOI: 10.1016/j.freeradbiomed.2012.12.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 11/14/2012] [Accepted: 12/17/2012] [Indexed: 11/24/2022]
Abstract
Reactive oxygen species (ROS) may serve as signals coupling metabolism to other cell functions. In addition to being by-products of normal metabolism, they are generated at elevated levels under environmental stress situations. We analyzed how reactive oxygen species affect the circadian clock in the model organism Neurospora crassa. In light/dark cycles, an increase in the levels of reactive oxygen species advanced the phase of both the conidiation rhythm and the expression of the clock gene frequency. Our results indicate a dominant role of the superoxide anion in the control of the phase. Elevation of superoxide production resulted in the activation of protein phosphatase 2A, a regulator of the positive element of the circadian clock. Our data indicate that even under nonstress conditions, reactive oxygen species affect circadian timekeeping. Reduction of their basal levels results in a delay of the phase in light/dark cycles and a longer period under constant conditions. We show that under entrained conditions the phase depends on the temperature and reactive oxygen species contribute to this effect. Our results suggest that the superoxide anion is an important factor controlling the circadian oscillator and is able to reset the clock most probably by activating protein phosphatase 2A, thereby modulating the activity of the White Collar complex.
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Ella K, Mócsai A, Káldi K. Circadian regulation of neutrophils: Control by a cell-autonomous clock or systemic factors? Eur J Clin Invest 2018; 48 Suppl 2:e12965. [PMID: 29877596 DOI: 10.1111/eci.12965] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 06/05/2018] [Indexed: 12/28/2022]
Abstract
BACKGROUND The circadian time-measuring system enables the organism to anticipate and effectively respond to regular daily changes in the environment and is therefore a crucial factor of adaptation. A large body of epidemiological data underlines the circadian characteristics of human immune functions. Circadian control of neutrophil responsiveness contributes to daily changes in the pathology of both acute and chronic inflammation and may therefore time-dependently influence the outcome of therapeutic approaches. AIM This review summarizes recent data on the role of the circadian clock in the control of immune responses, particularly of those linked to neutrophil activity, and possible mechanisms of the regulation. DISCUSSION In the first section of this review we present the recent model of the mammalian molecular clock by introducing the main transcription-translation feedback loops and discussing the pace-setting role of post-translational modifications. The next sections summarize clinical, epidemiological and experimental data regarding the daily control of immune responses and studies analysing expression of clock components in various leukocytes and particularly, in human peripheral neutrophils. As the latter data indicate that expression of components of the cell-autonomous clock is relatively low in neutrophils, in the last section we review recent findings suggesting a role for systemic and local factors in the regulation of rhythmic neutrophil responses.
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Review |
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Gyöngyösi N, Szőke A, Ella K, Káldi K. The small G protein RAS2 is involved in the metabolic compensation of the circadian clock in the circadian model Neurospora crassa. J Biol Chem 2017; 292:14929-14939. [PMID: 28729421 DOI: 10.1074/jbc.m117.804922] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Indexed: 11/06/2022] Open
Abstract
Accumulating evidence from both experimental and clinical investigations indicates a tight interaction between metabolism and circadian timekeeping; however, knowledge of the underlying mechanism is still incomplete. Metabolic compensation allows circadian oscillators to run with a constant speed at different substrate levels and, therefore, is a substantial criterion of a robust rhythm in a changing environment. Because previous data have suggested a central role of RAS2-mediated signaling in the adaptation of yeast to different nutritional environments, we examined the involvement of RAS2 in the metabolic regulation of the clock in the circadian model organism Neurospora crassa We show that, in a ras2-deficient strain, the period is longer than in the control. Moreover, unlike in the WT, in Δras2, operation of the circadian clock was affected by glucose; compared with starvation conditions, the period was longer and the oscillation of expression of the frequency (frq) gene was dampened. In constant darkness, the delayed phosphorylation of the FRQ protein and the long-lasting accumulation of FRQ in the nucleus were in accordance with the longer period and the less robust rhythm in the mutant. Although glucose did not affect the subcellular distribution of FRQ in the WT, highly elevated FRQ levels were detected in the nucleus in Δras2 RAS2 interacted with the RAS-binding domain of the adenylate cyclase in vitro, and the cAMP analogue 8-bromo-cyclic AMP partially rescued the circadian phenotype in vivo We therefore propose that RAS2 acts via a cAMP-dependent pathway and exerts significant metabolic control on the Neurospora circadian clock.
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Ella K, Sűdy ÁR, Búr Z, Koós B, Kisiczki ÁS, Mócsai A, Káldi K. Time restricted feeding modifies leukocyte responsiveness and improves inflammation outcome. Front Immunol 2022; 13:924541. [PMID: 36405720 PMCID: PMC9666763 DOI: 10.3389/fimmu.2022.924541] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 09/30/2022] [Indexed: 11/05/2022] Open
Abstract
Time restricted eating, the dietary approach limiting food intake to a maximal 10-hour period of daytime is considered beneficial in metabolic dysfunctions, such as obesity and diabetes. Rhythm of food intake and parallel changes in serum nutrient levels are also important entrainment signals for the circadian clock, particularly in tissues involved in metabolic regulation. As both the metabolic state and the circadian clock have large impact on immune functions, we investigated in mice whether time restricted feeding (TRF) affects systemic inflammatory potential. TRF slackened the symptoms in K/BxN serum-transfer arthritis, an experimental model of human autoimmune joint inflammation. Compared to ad libitum conditions TRF reduced the expression of inflammatory mediators in visceral adipose tissue, an integrator and coordinator of metabolic and inflammatory processes. Furthermore, TRF strengthened the oscillation of peripheral leukocyte counts and alongside decreased the pool of both marginated and tissue leukocytes. Our data suggest that the altered leukocyte distribution in TRF mice is related to the attenuated expression of adhesion molecules on the surface of neutrophils and monocytes. We propose that TRF modifies both rhythm and inflammatory potential of leukocytes which contribute to the milder reactivity of the immune system and therefore time-restricted eating could serve as an effective complementary tool in the therapy of autoinflammatory processes.
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Kumar D, Gauthami S, Madala U, Panduranga Rao P, Ella K, Hegde N. An Ebola vaccine candidate based on controlled expression of antigen through the recombinant adenovirus system. Int J Infect Dis 2016. [DOI: 10.1016/j.ijid.2016.02.896] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Czárán D, Sasvári P, Lőrincz K, Ella K, Gellén V, Csépányi-Kömi R. ARHGAP25: a novel player in the Pathomechanism of allergic contact hypersensitivity. Front Immunol 2025; 16:1509713. [PMID: 40078992 PMCID: PMC11896868 DOI: 10.3389/fimmu.2025.1509713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2024] [Accepted: 02/10/2025] [Indexed: 03/14/2025] Open
Abstract
Objective Contact hypersensitivity (CHS), or allergic contact dermatitis (ACD), is an inflammatory skin disorder characterized by an exaggerated allergic reaction to specific haptens. During this delayed-type allergic reaction, the first contact with the allergen initiates the sensitization phase, forming memory T cells. Upon repeated contact with the hapten, the elicitation phase develops, activating mostly macrophages, cytotoxic T cells, and neutrophilic granulocytes. Our group previously demonstrated that the leukocyte-specific GTPase-activating protein ARHGAP25 regulates phagocyte effector functions and is crucial in the pathomechanism of autoantibody-induced arthritis. Here, we investigate its role in the pathogenesis of the more complex inflammatory process of contact hypersensitivity. Methods For sensitization, the abdomens of wild-type and ARHGAP25 deficient (KO) mice on a C57BL/6 background, as well as bone marrow chimeric mice, were coated with 3% TNCB (2-chloro-1,3,5-trinitrobenzene) or acetone in the control group. After five days, ears were treated with 1% TNCB for elicitation. Swelling of the ears caused by edema formation was evaluated by measuring the ear thickness. Afterward, ears were harvested, and histological analysis, investigation of leukocyte infiltration, cytokine production, and changes in relevant signaling pathways were carried out. ARHGAP25 expression at the mRNA and protein levels was measured using murine ear and human skin samples. Results ARHGAP25 expression increased in human patients suffering from contact dermatitis and in contact hypersensitivity induced in mice. Our data suggest that ARHGAP25 expression is infinitesimal in keratinocytes. In the CHS mouse model, the absence of ARHGAP25 mitigated the severity of inflammation in a leukocyte-dependent manner by reducing the infiltration of phagocytes and cytotoxic T cells. ARHGAP25 altered cytokine composition in the sensitization and elicitation phase of the disease. However, this protein did not affect T cell homing and activation in the sensitization phase. Conclusion Our findings suggest that ARHGAP25 is essential in developing contact hypersensitivity by modulating the cytokine environment and leukocyte infiltration. Based on these findings, we propose ARHGAP25 as a promising candidate for future therapeutic approaches and a potential ACD biomarker.
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Búr Z, Vendl B, Sűdy ÁR, Lumniczky Z, Szántó CG, Mócsai A, Káldi K, Ella K. Time-restricted feeding alleviates arthritis symptoms augmented by high-fat diet. Front Immunol 2025; 16:1512328. [PMID: 40018036 PMCID: PMC11864949 DOI: 10.3389/fimmu.2025.1512328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2024] [Accepted: 01/10/2025] [Indexed: 03/01/2025] Open
Abstract
Rheumatoid arthritis (RA) affects approximately 1% of the global population. Its hallmark symptoms include severe pain and joint stiffness, which significantly diminish life quality. RA's development is influenced by multiple factors including unhealthy lifestyle habits. Calorie-rich diets, particularly those high in fat and resulting in obesity, are associated with RA and exacerbate its symptoms. Consequently, dietary modifications are recommended as a complementary treatment. However, adherence is often low due to the restrictive changes required in nutrient composition or caloric intake. Our previous findings indicate that time-restricted feeding (TRF) benefits leukocyte rhythm and mitigates autoimmune responses. In this study we explored the impact of TRF on the severity of K/BxN serum-transfer arthritis (STA) in mice subjected to high-fat diet. Three feeding schedules were implemented: a control (Ctrl) with constant access to standard chow, a high-fat diet group (HF) with ad libitum food access, and a high-fat TRF group (HF-TRF) with a 10-hour feeding window during the active phase. After four weeks of conditioning, STA was induced. Although macroscopic markers of inflammation did not differ between the Ctrl and HF groups, histological analysis revealed increased inflammation in HF mice, including expanded edema, pannus formation, bone erosion, elevated synovial neutrophil infiltration and serum leptin levels. Importantly, all these inflammatory markers were significantly reduced in the HF-TRF group, along with synovial IL-1β and monocyte/macrophage counts. Our results indicate that TRF can diminish the impact of a high-fat diet on STA severity, potentially serving as a preventive method and a sustainable therapeutic support for RA management.
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Kandaswamy S, Ella K. BBIL-5: An investigational new biotherapeutic for treating drug resistant S.aureus infections. Int J Infect Dis 2016. [DOI: 10.1016/j.ijid.2016.02.319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Czárán D, Sasvári P, Horváth ÁI, Ella K, Sűdy ÁR, Borbély É, Rusznák K, Czéh B, Mócsai A, Helyes Z, Csépányi-Kömi R. Lacking ARHGAP25 mitigates the symptoms of autoantibody-induced arthritis in mice. Front Immunol 2023; 14:1182278. [PMID: 37234175 PMCID: PMC10208528 DOI: 10.3389/fimmu.2023.1182278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 04/24/2023] [Indexed: 05/27/2023] Open
Abstract
Objective Despite intensive research on rheumatoid arthritis, the pathomechanism of the disease is still not fully understood and the treatment has not been completely resolved. Previously we demonstrated that the GTPase-activating protein, ARHGAP25 has a crucial role in the regulation of basic phagocyte functions. Here we investigate the role of ARHGAP25 in the complex inflammatory process of autoantibody-induced arthritis. Methods Wild-type and ARHGAP25 deficient (KO) mice on a C57BL/6 background, as well as bone marrow chimeric mice, were treated i.p. with the K/BxN arthritogenic or control serum, and the severity of inflammation and pain-related behavior was measured. Histology was prepared, leukocyte infiltration, cytokine production, myeloperoxidase activity, and superoxide production were determined, and comprehensive western blot analysis was conducted. Results In the absence of ARHGAP25, the severity of inflammation, joint destruction, and mechanical hyperalgesia significantly decreased, similarly to phagocyte infiltration, IL-1β, and MIP-2 levels in the tibiotarsal joint, whereas superoxide production or myeloperoxidase activity was unchanged. We observed a significantly mitigated phenotype in KO bone marrow chimeras as well. In addition, fibroblast-like synoviocytes showed comparable expression of ARHGAP25 to neutrophils. Significantly reduced ERK1/2, MAPK, and I-κB protein signals were detected in the arthritic KO mouse ankles. Conclusion Our findings suggest that ARHGAP25 has a key role in the pathomechanism of autoantibody-induced arthritis in which it regulates inflammation via the I-κB/NF-κB/IL-1β axis with the involvement of both immune cells and fibroblast-like synoviocytes.
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