Peripheral immune circadian variation, synchronisation and possible dysrhythmia in established type 1 diabetes.

AIMS/HYPOTHESIS: The circadian clock influences both diabetes and immunity. Our goal in this study was to characterise more thoroughly the circadian patterns of immune cell populations and cytokines that are particularly relevant to the immune pathology of type 1 diabetes and thus fill in a current gap in our understanding of this disease. METHODS: Ten individuals with established type 1 diabetes (mean disease duration 11 years, age 18-40 years, six female) participated in a circadian sampling protocol, each providing six blood samples over a 24 h period. RESULTS: Daily ranges of population frequencies were sometimes large and possibly clinically significant. Several immune populations, such as dendritic cells, CD4 and CD8 T cells and their effector memory subpopulations, CD4 regulatory T cells, B cells and cytokine IL-6, exhibited statistically significant circadian rhythmicity. In a comparison with historical healthy control individuals, but using shipped samples, we observed that participants with type 1 diabetes had statistically significant phase shifts occurring in the time of peak occurrence of B cells (+4.8 h), CD4 and CD8 T cells (~ +5 h) and their naive and effector memory subsets (~ +3.3 to +4.5 h), and regulatory T cells (+4.1 h). An independent streptozotocin murine experiment confirmed the phase shifting of CD8 T cells and suggests that circadian dysrhythmia in type 1 diabetes might be an effect and not a cause of the disease. CONCLUSIONS/INTERPRETATION: Future efforts investigating this newly described aspect of type 1 diabetes in human participants are warranted. Peripheral immune populations should be measured near the same time of day in order to reduce circadian-related variation.

Chronic circadian disruption modulates breast cancer stemness and immune microenvironment to drive metastasis in mice.

Breast cancer is the most common type of cancer worldwide and one of the major causes of cancer death in women. Epidemiological studies have established a link between night-shift work and increased cancer risk, suggesting that circadian disruption may play a role in carcinogenesis. Here, we aim to shed light on the effect of chronic jetlag (JL) on mammary tumour development. To do this, we use a mouse model of spontaneous mammary tumourigenesis and subject it to chronic circadian disruption. We observe that circadian disruption significantly increases cancer-cell dissemination and lung metastasis. It also enhances the stemness and tumour-initiating potential of tumour cells and creates an immunosuppressive shift in the tumour microenvironment. Finally, our results suggest that the use of a CXCR2 inhibitor could correct the effect of JL on cancer-cell dissemination and metastasis. Altogether, our data provide a conceptual framework to better understand and manage the effects of chronic circadian disruption on breast cancer progression.

Multiple Sclerosis: Melatonin, Orexin, and Ceramide Interact with Platelet Activation Coagulation Factors and Gut-Microbiome-Derived Butyrate in the Circadian Dysregulation of Mitochondria in Glia and Immune Cells.

Recent data highlight the important roles of the gut microbiome, gut permeability, and alterations in mitochondria functioning in the pathophysiology of multiple sclerosis (MS). This article reviews such data, indicating two important aspects of alterations in the gut in the modulation of mitochondria: (1) Gut permeability increases toll-like receptor (TLR) activators, viz circulating lipopolysaccharide (LPS), and exosomal high-mobility group box (HMGB)1. LPS and HMGB1 increase inducible nitric oxide synthase and superoxide, leading to peroxynitrite-driven acidic sphingomyelinase and ceramide. Ceramide is a major driver of MS pathophysiology via its impacts on glia mitochondria functioning; (2) Gut dysbiosis lowers production of the short-chain fatty acid, butyrate. Butyrate is a significant positive regulator of mitochondrial function, as well as suppressing the levels and effects of ceramide. Ceramide acts to suppress the circadian optimizers of mitochondria functioning, viz daytime orexin and night-time melatonin. Orexin, melatonin, and butyrate increase mitochondria oxidative phosphorylation partly via the disinhibition of the pyruvate dehydrogenase complex, leading to an increase in acetyl-coenzyme A (CoA). Acetyl-CoA is a necessary co-substrate for activation of the mitochondria melatonergic pathway, allowing melatonin to optimize mitochondrial function. Data would indicate that gut-driven alterations in ceramide and mitochondrial function, particularly in glia and immune cells, underpin MS pathophysiology. Aryl hydrocarbon receptor (AhR) activators, such as stress-induced kynurenine and air pollutants, may interact with the mitochondrial melatonergic pathway via AhR-induced cytochrome P450 (CYP)1b1, which backward converts melatonin to N-acetylserotonin (NAS). The loss of mitochnodria melatonin coupled with increased NAS has implications for altered mitochondrial function in many cell types that are relevant to MS pathophysiology. NAS is increased in secondary progressive MS, indicating a role for changes in the mitochondria melatonergic pathway in the progression of MS symptomatology. This provides a framework for the integration of diverse bodies of data on MS pathophysiology, with a number of readily applicable treatment interventions, including the utilization of sodium butyrate.

Resveratrol Prevents Acrylamide-Induced Mitochondrial Dysfunction and Inflammatory Responses via Targeting Circadian Regulator Bmal1 and Cry1 in Hepatocytes.

Acrylamide, mainly formed in Maillard browning reaction during food processing, causes defects in liver circadian clock and mitochondrial function by inducing oxidative stress. Resveratrol is a polyphenol that has powerful antioxidant and anti-inflammatory activity. However, the preventive effects of resveratrol on acrylamide-triggered oxidative damage and circadian rhythm disorders are unclear at the current stage. The present research revealed that resveratrol pretreatment prevented acrylamide-induced cell death, mitochondrial dysfunction, and inflammatory responses in HepG2 liver cells. Acrylamide significantly triggered disorders of circadian genes transcription and protein expressions including Bmal1 and Cry 1 in primary hepatocytes, which were prevented by resveratrol pretreatment. Moreover, we found that the beneficial effects of resveratrol on stimulating Nrf2/NQO-1 pathway and mitochondrial respiration complex expressions in acrylamide-treated cells were Bmal1-dependent. Similarly, the inhibitory effects of resveratrol on inflammation signaling NF-κB were Cry1-dependent. In conclusion, these results demonstrated resveratrol could be a promising compound in suppressing acrylamide-induced hepatotoxicity and balancing the circadian clock.

Aging renders desynchronization between clock and immune genes in male Wistar rat kidney: chronobiotic role of curcumin.

Suprachiasmatic nucleus (SCN) contains the central clock that orchestrate circadian rhythms in physiology and behavior in mammals. Tightly interlocked transcriptional and translational feedback loops (TTFLs) comprising of various clock genes such as Clock, Bmal1, Periods, Cryptochromes etc. in the SCN, send the timing signals to peripheral clocks that governs local metabolism with similar TTFLs. Peripheral clocks in kidney regulates several circadian rhythms like blood pressure, immunity etc. However, aging leads to circadian and inflammatory disorders in kidney. Though there are increasing evidences on age associated perturbations, studies elucidating the rhythmic expression of clock and immune genes across aging in kidney are obscure. We therefore studied changes in daily rhythms of clock and immune genes in kidney. In this study we measured mRNA expression of clock genes rBmal1, rPer1, rPer2, rCry1, rCry2, rRev-erbα, rRorα, and inflammatory genes rNfκb1, rTnfα, rIl6, rTlr4 and rTlr9 in 3, 12 and 24 months male Wistar rat kidney using qRT-PCR. From our study, we did not observe significant changes in clock genes expression except rRorα, but immune genes showed significant phase alterations as well as increase in mean 24 h levels. Pearson correlation analysis of data showed desynchronization between immune and clock genes expression. We further studied the effect of administration of curcumin which has anti-aging, anti-inflammatory, anti-oxidant etc. properties, and evaluated its chronobiotic properties. We here report differential effects of curcumin administration on daily rhythms of clock and immune genes expression.

Western lifestyle and immunopathology of multiple sclerosis.

There is increasing evidence for a sudden and unprecedented rise in the incidence of multiple sclerosis (MS) in Westernized countries over the past decades, emphasizing the role of environmental factors. Among many candidates, rapid changes in dietary habits seem to play a role in the pathogenesis of MS. Here, we summarize and discuss the available evidence for the role of dietary nutrients, such as table salt, fatty acids, and flavonoids, in the development and pathogenesis of MS. We also discuss new and emerging risk factors accompanying Western lifestyle, such as shift work, sleep, and circadian disruption.

Disruption of Circadian Rhythms and Sleep in Critical Illness and its Impact on Innate Immunity.

The earth rotates on its axis around the sun, creating a day and night cycle, that caused the development of circadian rhythms. The circadian rhythm is primarily entrained by light, which is detected by the retina. Retinal ganglion cells project to a part of the hypothalamus termed suprachiasmatic nucleus. Here, we find the master molecular clock, composed of a transcription-translation-loop at its core. The master clock indirectly influences the innate immune system via different biological systems. Also, the master clock controls the peripheral clocks, which are present in innate immune cells. Here, circadian rhythm proteins influence the response of immune cells to pathogens. Furthermore, the master clock influences our sleep-pattern, the most important restorative physiological function. In critically ill patients the circadian rhythm is substantially altered, supporting a dysfunctional innate immune response. This review discusses recent basic science findings on the interaction of the circadian rhythm and the innate immune system. Furthermore we give an outlook on potential future therapeutic strategies.

Shift Work in Rats Results in Increased Inflammatory Response after Lipopolysaccharide Administration: A Role for Food Consumption.

The suprachiasmatic nucleus (SCN) drives circadian rhythms in behavioral and physiological variables, including the inflammatory response. Shift work is known to disturb circadian rhythms and is associated with increased susceptibility to develop disease. In rodents, circadian disruption due to shifted light schedules (jet lag) induced increased innate immune responses. To gain more insight into the influence of circadian disruption on the immune response, we characterized the inflammatory response in a model of rodent shift work and demonstrated that circadian disruption affected the inflammatory response to lipopolysaccharide (LPS) both in vivo and in vitro. Since food consumption is a main disturbing element in the shift work schedule, we also evaluated the inflammatory response to LPS in a group of rats that had no access to food during their working hours. Our results demonstrated that the shift work schedule decreased basal TNF-α levels in the liver but not in the circulation. Despite this, we observed that shift work induced increased cytokine response after LPS stimulation in comparison to control rats. Also, Kupffer cells (liver macrophages) isolated from shift work rats produced more TNF-α in response to in vitro LPS stimulation, suggesting important effects of circadian desynchronization on the functionality of this cell type. Importantly, the effects of shift work on the inflammatory response to LPS were prevented when food was not available during the working schedule. Together, these results show that dissociating behavior and food intake from the synchronizing drive of the SCN severely disturbs the immune response.

A study on circadian rhythm disorder of rat lung tissue caused by mechanical ventilation induced lung injury.

Ventilator-induced lung injury (VILI), the most serious complication of mechanical ventilation therapy, is an excessive inflammatory response in lung tissue characterized by infiltration of inflammatory cells and overproduction of inflammatory mediators. The pathogenesis of VILI is very complex. It is becoming increasingly evident that disruption of circadian rhythm affects the immune response. Whether the pathogenesis of VILI is associated with circadian rhythm disruption has not been reported. In this study, we establish VILI model in SD rat by performing an endotracheal intubation and placing the rat on a mechanical ventilator (tidal volume of 40 ml/kg or 10 ml/kg without positive end-expiratory pressure). To examine the effect of VILI on clock gene expression, real-time quantitative PCR was performed to measure bmal1, clock, per2 and Rev-erbα mRNA expression. We found that Rev-erbα mRNA was significantly decreased in high tide volume mechanical ventilation group compared with spontaneous group, the same as REV-ERBα protein product which was tested by Western blot approach. Stimulation of REV-ERBα activity by SR9009 greatly diminished VILI-induced lung edema, inflammatory cell infiltration and the production of the pro-inflammatory cytokine TNF-α. Collectively, our findings are the first to show that REV-ERBα plays an important role in VILI and inflammation, and circadian rhythm disorder in inflammation response may be a novel pathogenesis of VILI.

Circadian disruption: potential implications in inflammatory and metabolic diseases associated with alcohol.

Circadian rhythms are a prominent and critical feature of cells, tissues, organs, and behavior that help an organism function most efficiently and anticipate things such as food availability. Therefore, it is not surprising that disrupted circadian rhythmicity, a prominent feature of modern-day society, promotes the development and/or progression of a wide variety of diseases, including inflammatory, metabolic, and alcohol-associated disorders. This article will discuss the influence of interplay between alcohol consumption and circadian rhythmicity and how circadian rhythm disruption affects immune function and metabolism as well as potential epigenetic mechanisms that may be contributing to this phenomenon.

The relationship between neutrophil lymphocyte ratio and non-dipper hypertension.

Non-dipper hypertension is associated with increased cardiovascular morbidity and mortality. Neutrophil/lymphocyte ratio (NLR) has been associated with poor outcomes in patients with cardiovascular diseases. However, little is known about the role of NLR in patients with non-dipper hypertension. In this study, NLR between dipper and non-dipper hypertensive patients was compared.This study included 80 hypertensive patients. Hypertensive patients were divided into two groups: 50 dipper patients (29 male, mean age 51.5 ± 8 years) and 30 non-dipper patients (17 male, mean age 50.6 ± 5.4 years). Transthoracic echocardiography and ambulatory 24-hour blood pressure monitoring were performed on all patients. No patient had a recent history of an acute infection or an inflammatory disease. Baseline NLR was measured by dividing neutrophil count to lymphocyte count. No statistically significant difference was found between the two groups in terms of basic characteristics. Mean NLR was significantly higher among persons with non-dipper compared with dipper patients (3.1 ± 0.95 vs. 1.8 ± 0.52, P < .001). Additionally, leukocytes and monocytes counts were higher in patients with non-dipper hypertension.In conclusion, our results suggest that higher NLR, an emerging marker of inflammation, has a positive correlation with blood pressure and is elevated in non-dippers compared with dippers.

Circadian control of the immune system.

Circadian rhythms, which have long been known to play crucial roles in physiology, are emerging as important regulators of specific immune functions. Circadian oscillations of immune mediators coincide with the activity of the immune system, possibly allowing the host to anticipate and handle microbial threats more efficiently. These oscillations may also help to promote tissue recovery and the clearance of potentially harmful cellular elements from the circulation. This Review summarizes the current knowledge of circadian rhythms in the immune system and provides an outlook on potential future implications.

Chronic shift-lag alters the circadian clock of NK cells and promotes lung cancer growth in rats.

Prolonged subjection to unstable work or lighting schedules, particularly in rotating shift-workers, is associated with an increased risk of immune-related diseases, including several cancers. Consequences of chronic circadian disruption may also extend to the innate immune system to promote cancer growth, as NK cell function is modulated by circadian mechanisms and plays a key role in lysis of tumor cells. To determine if NK cell function is disrupted by a model of human shift-work and jet-lag, Fischer (344) rats were exposed to either a standard 12:12 light-dark cycle or a chronic shift-lag paradigm consisting of 10 repeated 6-h photic advances occurring every 2 d, followed by 5-7 d of constant darkness. This model resulted in considerable circadian disruption, as assessed by circadian running-wheel activity. NK cells were enriched from control and shifted animals, and gene, protein, and cytolytic activity assays were performed. Chronic shift-lag altered the circadian expression of clock genes, Per2 and Bmal1, and cytolytic factors, perforin and granzyme B, as well as the cytokine, IFN-γ. These alterations were correlated with suppressed circadian expression of NK cytolytic activity. Further, chronic shift-lag attenuated NK cell cytolytic activity under stimulated in vivo conditions, and promoted lung tumor growth following i.v. injection of MADB106 tumor cells. Together, these findings suggest chronic circadian disruption promotes tumor growth by altering the circadian rhythms of NK cell function.

[Biological risk and health care workers: analysis of the effects of work chronobiology on the immune system]. / Rischio biologico ed operatori sanitari: analisi dell'interferenza tra cronobiologia lavorativa e sistema immunitario.

BACKGROUND: Healthcare workers may be exposed to a variety of biological hazards. Although many studies have shown that some immunological alterations were related to work stress and sleep disorders, few studies investigated effects of shiftwork on the immunological system. OBJECTIVES: The aim of the study was to compare the immune status of a group of nurses on shiftwork with that of nurses working only day shifts. METHODS: A total of 138 nurses were evaluated at baseline and after a year of follow-up, via tests for perceived stress, daytime sleepiness, number of lymphocytes and subpopulation of CD3+, CD4+, CD8+-CD57+, CD19+ and CD56+, cytotoxic activity and lympho-prolferative response of NK cells, serum concentrations of IL-1beta, IL-6, INFgamma and TNFalpha. RESULTS AND CONCLUSION: No significant alterations of any of the studied parameters were found both at baseline and after a year of follow-up. The biological hazards for nurses do not seem to be increased by shiftwork.

The influence of experimental desynchronosis on the morphofunctional characteristics of mouse immune system.

The aim of this study is to investigate the influence of experimental desynchronosis on the immune system and estimate benzo[a]pyrene (BP) influence on the immune reactivity of mice under the condition of desyncronosis (DS) in comparison with intact organisms. Mice (CBA X C57BL)F1 were kept under constant light during two weeks and natural alternation of darkness and light (control group). Animals of the two groups received benzo[a]pyrene solution in olive oil. The existence of diurnal variation of cell populations of lymphoid organs and blood, humoral immune response to SRBC were revealed. Changes of diurnal dynamics of these parameters and decrease of humoral immune response to SRBC have been observed in animals kept under constant light in comparison with animals kept under standard light conditions. It is likely to indicate the development of internal DS. BP influenced the cellular composition and immune response of intact and DS animals in a different way. So, the changes of light regime lead to development of the internal DS of immune system that influenced its functional capacity and sensitivity to damaging effect of chemical ecological factor.

Effect of experimental desynchronosis on immunotoxicity of benz(a)pyrene in (CBAxC57Bl)F1 mice.

Experiments on (CBA x C57Bl)F1 mice showed that constant (day and night) illumination for 2 weeks led to the development of internal desynchronosis, which significantly modulated the reaction of the immune system to benz(a)pyrene compared to those in intact animals. Presumably, the differences were associated with changed circadian rhythms of the immune parameters in experimental animals determining different ratios and, presumably, functions of immunocompetent cells during benz(a)pyrene exposure in intact controls and animals with desynchronosis.

[Changes in liver and in some organs of immune system of animals exposed to twenty-four-hour illumination].

The aim of this research was to study the morpho-functional organization of liver and some organs of immune system in animals exposed to continous twenty-four-hour illumination (CI) for 14 days. Using the methods of light and electron microscopy and morphometric analysis of histological preparations, liver and regional lymph nodes (hepatic in rats and iliac in mice) were studied. It was found that CI resulted in a state of dyschronosis, which was structurally manifested by the changes of diurnal variations of morphometric parameters of liver and its draining lymph nodes, disturbances of hemo- and lymphocirculation, destruction of cellular membranes. Response of central and peripheral organs of immune system to CI included the changes of diurnal variations of blast forms and mature lymphocytes, that was also indicative of dyschronosis development.

Age-dependent changes in 24-hour rhythms of thymic and circulating growth hormone and adrenocorticotropin in rats injected with Freund's adjuvant.

OBJECTIVE: To analyze the 24-hour changes in thymic and serum concentration of growth hormone (GH) and adrenocorticotropin (ACTH) and their correlation with thymic concentrations of glutamate, aspartate, taurine and GABA in young and old rats during the acute phase of adjuvant's arthritis. METHODS: Young (50-day-old) and old (18-month-old) rats were injected subcutaneously with Freund's adjuvant or its vehicle (paraffin oil containing 15% mannide monooleate). Eighteen days later, they were killed at six different time intervals throughout a 24-hour cycle. Serum and thymic levels of GH and ACTH were measured by radioimmunoassay. Thymic amino acid concentration was measured by HPLC. A quantitative assessment of arthritis was made in an independent group of rats by plethysmography. RESULTS: Old rats injected with Freund's adjuvant exhibited fewer clinical signs of inflammation than young rats. Significant 24-hour changes in thymic and serum GH occurred, except for serum GH in adjuvant's vehicle-treated old rats. Aging augmented thymic GH and decreased serum GH. Immunization with Freund's adjuvant did not modify GH concentration. Thymic and serum concentration of GH correlated negatively. Thymic ACTH varied significantly over 24 h with maxima during the dark phase, except in Freund's adjuvant-treated young rats. Maximal serum ACTH levels occurred in the late afternoon except in Freund's adjuvant-treated old rats which showed maxima at night. Immunization with Freund's adjuvant augmented thymic and circulating concentrations of ACTH. Thymic and serum concentration of ACTH correlated positively. Thymic concentration of glutamate, aspartate and taurine decreased in aged rats and correlated significantly with thymic ACTH. CONCLUSION: The results support the existence of a thymic compartment of GH and ACTH that may be independently regulated.