NCoA3 upregulation in breast cancer­associated adipocytes elicits an inflammatory profile.

Nuclear receptor coactivator 3 (NCoA3) is a transcriptional coactivator of NF­κB and other factors, which is expressed at relatively low levels in normal cells and is amplified or overexpressed in several types of cancer, including breast tumors. NCoA3 levels have been shown to be decreased during adipogenesis; however, its role in tumor­surrounding adipose tissue (AT) remains unknown. Therefore, the present study assessed the modulation of NCoA3 in breast cancer­associated adipocytes and evaluated its association with the expression of inflammatory markers. 3T3­L1 adipocytes were stimulated with conditioned medium from human breast cancer cell lines and the expression levels of NCoA3 were evaluated by reverse transcription­quantitative (q)PCR. NF­κB activation was measured by immunofluorescence, and tumor necrosis factor and monocyte chemoattractant protein 1 levels were analyzed by qPCR and dot blot assays. The results obtained from the in vitro model were supported using mammary AT (MAT) from female mice, MAT adjacent to tumors from patients with breast cancer and bioinformatics analysis. The results revealed that adipocytes expressing high levels of NCoA3 were mainly associated with a pro­inflammatory profile. In 3T3­L1 adipocytes, NCoA3 downregulation or NF­κB inhibition reversed the expression of inflammatory molecules. In addition, MAT from patients with a worse prognosis exhibited high levels of this coactivator. Notably, adipocyte NCoA3 levels could be modulated by inflammatory signals from tumors. The modulation of NCoA3 levels in synergy with NF­κB activity in MAT in a tumor context could be factors required to establish breast cancer­associated inflammation. As adipocytes are involved in the development and progression of breast cancer, this signaling network deserves to be further investigated to improve future tumor treatments.

Circadian disruption induced by tumor development in a murine model of melanoma.

The circadian system induces oscillations in most physiological variables, with periods close to 24 hours. Dysfunctions in clock-controlled body functions, such as sleep disorders, as well as deregulation of clock gene expression or glucocorticoid levels have been observed in cancer patients. Moreover, these disorders have been associated with a poor prognosis or worse response to treatment. This work explored the circadian rhythms at behavioral and molecular levels in a murine melanoma model induced by subcutaneous inoculation of B16 tumoral cells. We observed that the presence of the tumors induced a decrease in the robustness of the locomotor activity rhythms and in the amount of nighttime activity, together with a delay in the acrophase and in the activity onset. Moreover, these differences were more marked when the tumor size was larger than in the initial stages of the tumorigenesis protocol. In addition, serum glucocorticoids, which exhibit strong clock-controlled rhythms, lost their circadian patterns. Similarly, the rhythmic expression of the clock genes Bmal1 and Cry1 in the hypothalamic Suprachiasmatic Nuclei (SCN) were also deregulated in mice carrying tumors. Altogether, these results suggest that tumor-secreted molecules could modulate the function of the central circadian pacemaker (SCN). This could account for the worsening of the peripheral biological rhythms such as locomotor activity or serum glucocorticoids. Since disruption of the circadian rhythms might accelerate tumorigenesis, monitoring circadian patterns in cancer patients could offer a new tool to get a better prognosis for this disease.

Differential Thermoregulatory and Inflammatory Patterns in the Circadian Response to LPS-Induced Septic Shock.

Sepsis is caused by a dysregulated host response to infection, and characterized by uncontrolled inflammation together with immunosuppression, impaired innate immune functions of phagocytes and complement activation. Septic patients develop fever or hypothermia, being the last one characteristic of severe cases. Both lipopolysaccharide (LPS) and Tumor Necrosis Factor (TNF)-α- induced septic shock in mice is dependent on the time of administration. In this study, we aimed to further characterize the circadian response to high doses of LPS. First, we found that mice injected with LPS at ZT11 developed a higher hypothermia than those inoculated at ZT19. This response was accompanied by higher neuronal activation of the preoptic, suprachiasmatic, and paraventricular nuclei of the hypothalamus. However, LPS-induced Tnf-α and Tnf-α type 1 receptor (TNFR1) expression in the preoptic area was time-independent. We also analyzed peritoneal and spleen macrophages, and observed an exacerbated response after ZT11 stimulation. The serum of mice inoculated with LPS at ZT11 induced deeper hypothermia in naïve animals than the one coming from ZT19-inoculated mice, related to higher TNF-α serum levels during the day. We also analyzed the response in TNFR1-deficient mice, and found that both the daily difference in the mortality rate, the hypothermic response and neuronal activation were lost. Moreover, mice subjected to circadian desynchronization showed no differences in the mortality rate throughout the day, and developed lower minimum temperatures than mice under light-dark conditions. Also, those injected at ZT11 showed increased levels of TNF-α in serum compared to standard light conditions. These results suggest a circadian dependency of the central thermoregulatory and peripheral inflammatory response to septic-shock, with TNF-α playing a central role in this circadian response.

Modulation of mammalian circadian rhythms by tumor necrosis factor-α.

UNLABELLED: Systemic low doses of the endotoxin lipopolysaccharide (LPS, 100 µg/kg) administered during the early night induce phase-delays of locomotor activity rhythms in mice. Our aim was to evaluate the role of tumor necrosis factor (Tnf)-alpha and its receptor 1/p55 (Tnfr1) in the modulation of LPS-induced circadian effects on the suprachiasmatic nucleus (SCN). We observed that Tnfr1-defective mice (Tnfr1 KO), although exhibiting similar circadian behavior and light response to that of control mice, did not show LPS-induced phase-delays of locomotor activity rhythms, nor LPS-induced cFos and Per2 expression in the SCN and Per1 expression in the paraventricular hypothalamic nucleus (PVN) as compared to wild-type (WT) mice. We also analyzed Tnfr1 expression in the SCN of WT mice, peaking during the early night, when LPS has a circadian effect. Peripheral inoculation of LPS induced an increase in cytokine/chemokine levels (Tnf, Il-6 and Ccl2) in the SCN and in the PVN. In conclusion, in this study, we show that LPS-induced circadian responses are mediated by Tnf. Our results also suggest that this cytokine stimulates the SCN after LPS peripheral inoculation; and the time-related effect of LPS (i.e. phase shifts elicited only at early night) might depend on the increased levels of Tnfr1 expression. We also confirmed that LPS modulates clock gene expression in the SCN and PVN in WT but not in Tnfr1 KO mice. HIGHLIGHTS: We demonstrate a fundamental role for Tnf and its receptor in circadian modulation by immune stimuli at the level of the SCN biological clock.

Suprachiasmatic astrocytes modulate the circadian clock in response to TNF-α.

The immune and the circadian systems interact in a bidirectional fashion. The master circadian oscillator, located in the suprachiasmatic nuclei (SCN) of the hypothalamus, responds to peripheral and local immune stimuli, such as proinflammatory cytokines and bacterial endotoxin. Astrocytes exert several immune functions in the CNS, and there is growing evidence that points toward a role of these cells in the regulation of circadian rhythms. The aim of this work was to assess the response of SCN astrocytes to immune stimuli, particularly to the proinflammatory cytokine TNF-α. TNF-α applied to cultures of SCN astrocytes from Per2(luc) knockin mice altered both the phase and amplitude of PER2 expression rhythms, in a phase-dependent manner. Furthermore, conditioned media from SCN astrocyte cultures transiently challenged with TNF-α induced an increase in Per1 expression in NIH 3T3 cells, which was blocked by TNF-α antagonism. In addition, these conditioned media could induce phase shifts in SCN PER2 rhythms and, when administered intracerebroventricularly, induced phase delays in behavioral circadian rhythms and SCN activation in control mice, but not in TNFR-1 mutants. In summary, our results show that TNF-α modulates the molecular clock of SCN astrocytes in vitro, and also that, in response to this molecule, SCN astrocytes can modulate clock gene expression in other cells and tissues, and induce phase shifts in a circadian behavioral output in vivo. These findings suggest a role for astroglial cells in the alteration of circadian timing by immune activation.

The times they're a-changing: effects of circadian desynchronization on physiology and disease.

Circadian rhythms are endogenous and need to be continuously entrained (synchronized) with the environment. Entrainment includes both coupling internal oscillators to external periodic changes as well as synchrony between the central clock and peripheral oscillators, which have been shown to exhibit different phases and resynchronization speed. Temporal desynchronization induces diverse physiological alterations that ultimately decrease quality of life and induces pathological situations. Indeed, there is a considerable amount of evidence regarding the deleterious effect of circadian dysfunction on overall health or on disease onset and progression, both in human studies and in animal models. In this review we discuss the general features of circadian entrainment and introduce diverse experimental models of desynchronization. In addition, we focus on metabolic, immune and cognitive alterations under situations of acute or chronic circadian desynchronization, as exemplified by jet-lag and shiftwork schedules. Moreover, such situations might lead to an enhanced susceptibility to diverse cancer types. Possible interventions (including light exposure, scheduled timing for meals and use of chronobiotics) are also discussed.

Characterization of locomotor activity circadian rhythms in athymic nude mice.

BACKGROUND: The relation between circadian dysregulation and cancer incidence and progression has become a topic of major interest over the last decade. Also, circadian timing has gained attention regarding the use of chronopharmacology-based therapeutics. Given its lack of functional T lymphocytes, due to a failure in thymus development, mice carrying the Foxn1(Δ/Δ) mutation (nude mice) have been traditionally used in studies including implantation of xenogeneic tumors. Since the immune system is able to modulate the circadian clock, we investigated if there were alterations in the circadian system of the athymic mutant mice. METHODS: General activity circadian rhythms in 2-4 month-old Foxn1(Δ/Δ) mice (from Swiss Webster background) and their corresponding wild type (WT) controls was recorded. The response of the circadian system to different manipulations (constant darkness, light pulses and shifts in the light-dark schedule) was analyzed. RESULTS: Free-running periods of athymic mice and their wild type counterpart were 23.86 ± 0.03 and 23.88 ± 0.05 hours, respectively. Both strains showed similar phase delays in response to 10 or 120 minutes light pulses applied in the early subjective night and did not differ in the number of c-Fos-expressing cells in the suprachiasmatic nuclei, after a light pulse at circadian time (CT) 15. Similarly, the two groups showed no significant difference in the time needed for resynchronization after 6-hour delays or advances in the light-dark schedule. The proportion of diurnal activity, phase-angle with the zeitgeber, subjective night duration and other activity patterns were similar between the groups. CONCLUSIONS: Since athymic Foxn1(Δ/Δ) mice presented no differences with the WT controls in the response of the circadian system to the experimental manipulations performed in this work, we conclude that they represent a good model in studies that combine xenograft implants with either alteration of the circadian schedules or chronopharmacological approaches to therapeutics.

Paying the circadian toll: the circadian response to LPS injection is dependent on the Toll-like receptor 4.

Systemic low doses of the endotoxin lipopolysaccharide (LPS) administered at CT15 (circadian time 12 corresponds to locomotor activity onset) induce phase delays of locomotor activity rhythms in mice. To evaluate if this effect was mediated by the Toll-like receptor 4 (TLR4), our present aim was to characterize the circadian behavior and LPS-induced circadian response of TLR4 (LPS receptor)-deficient mice (in C57bl/10 and C3H backgrounds). In mutants, we observed a free-running period and a light-induced phase delay similar to the one observed in their corresponding wild-type (WT) littermates. The LPS-induced phase delay, wheel running inhibition and c-Fos/Per-1 immunoreactivity in the paraventricular nuclei observed in WT mice was absent or significantly decreased in the TLR4-deficient mice. In conclusion, we show that LPS-induced circadian responses are mediated by TLR4.

NK cells expressing a progesterone receptor are susceptible to progesterone-induced apoptosis.

It has been proposed that progesterone (P4) induces the suppression of immune responses, particularly during pregnancy. However, knowledge about the mechanisms involved has remained largely elusive. We demonstrate herein that peripheral blood NK (PBNK) cells express both classical progesterone receptor (PR) isoforms and are specifically affected by the actions of P4 through two apparently independent mechanisms. Progesterone induces caspase-dependent PBNK cell death, which is reversed by two different anti-progestins, ZK 98.299 and RU 486, supporting the involvement of classical PR isoforms. It was suggested that CD56(bright)CD16(-) killer Ig-like receptor (KIR)(-) NK cells might represent precursor cells, which, upon activation, acquire the features of a more mature NK subset expressing KIR receptors. The present study demonstrates that PR expression seems to be restricted to more mature KIR(+) PBNK cells. The expression of PR had a functional counterpart in the suppressive effect of P4 on IL-12-induced IFN-gamma secretion. This cytokine suppression was mainly observed in KIR(+) PBNK cells, without affecting the high secretion of IFN-gamma by CD56(bright) PBNK cells. The lack of PR expression on CD56(bright)KIR(-) PBNK cells provides an additional phenotypic marker to test the idea that they might represent the PBNK precursors selectively recruited into the endometrium where they differentiate to become the uterine NK cells. Additionally, these findings may be relevant to NK cell function in viral immunity, human reproduction, and tumor immunity.

Simultaneous expression of Th1 cytokines and IL-4 confers severe characteristics to type I autoimmune hepatitis in children.

To investigate the immunopathogenic mechanisms of type I autoimmune hepatitis in children, we analyzed by quantitative or semiquantitative reverse transcription-polymerase chain reaction the expression of cytokines interferon (IFN)-gamma, interleukin (IL)-12p40, IL-18, IL-4, IL-10, and IL-12R beta 2. In addition, liver and peripheral blood was collected to investigate the expression of the natural killer T (NKT) cell marker V alpha 24. The presence of NKT cells in hepatic lesions were also identified by immunohistochemistry. The analysis was performed on liver biopsies from 25 children with type I autoimmune hepatitis. As disease controls, we included six children with hepatitis C virus-related chronic hepatitis and nine control livers. The expression of IFN-gamma and IL-12p40 was not detected in controls but was clearly upregulated in pathologic biopsies. In addition, these samples showed an increased expression of IL-18 (p = 0.0003), IL-4 (p = 0.0055), and IL-12R beta 2 (p = 0.007). Western blot analysis confirmed the expression of IL-12p40 and IL-18. However, for IL-18, we detected only the immature biologically inactive polypeptide. The V alpha 24 transcripts were found increased in the liver (p = 0.0007) where V alpha 24(+) cells were also localized, but decreased in peripheral blood mononuclear cells (p = 0.041). In addition to a type I immune response, NKT cells might play a substantial role in the pathogenesis of type I autoimmune hepatitis in children.