IL-10-induced STAT3/NF-κB crosstalk modulates pineal and extra-pineal melatonin synthesis.

Immune-pineal axis activation is part of the assembly of immune responses. Proinflammatory cytokines inhibit the pineal synthesis of melatonin while inducing it in macrophages by mechanisms dependent on nuclear factor-κB (NF-κB) activation. Cytokines activating the Janus kinase/signal transducer and activator of transcription (STAT) pathways, such as interferon-gamma (IFN-γ) and interleukin-10 (IL-10), modulate melatonin synthesis in the pineal, bone marrow (BM), and spleen. The stimulatory effect of IFN-γ upon the pineal gland depends on STAT1/NF-κB interaction, but the mechanisms controlling IL-10 effects on melatonin synthesis remain unclear. Here, we evaluated the role of STAT3 and NF-κB activation by IL-10 upon the melatonin synthesis of rats' pineal gland, BM, spleen, and peritoneal cells. The results show that IL-10-induced interaction of (p)STAT3 with specific NF-κB dimmers leads to different cell effects. IL-10 increases the pineal's acetylserotonin O-methyltransferase (ASMT), N-acetylserotonin, and melatonin content via nuclear translocation of NF-κB/STAT3. In BM, the nuclear translocation of STAT3/p65-NF-κB complexes increases ASMT expression and melatonin content. Increased pSTAT3/p65-NF-κB nuclear translocation in the spleen enhances phosphorylated serotonin N-acetyltransferase ((p)SNAT) expression and melatonin content. Conversely, in peritoneal cells, IL-10 leads to NF-κB p50/p50 inhibitory dimmer nuclear translocation, decreasing (p)SNAT expression and melatonin content. In conclusion, IL-10's effects on melatonin production depend on the NF-κB subunits interacting with (p)STAT3. Thus, variations of IL-10 levels and downstream pathways during immune responses might be critical regulatory factors adjusting pineal and extra-pineal synthesis of melatonin.

Rat resistance to rheumatoid arthritis induction as a function of the early-phase adrenal-pineal crosstalk.

Chronic inflammatory diseases are triggered by causal stimuli that might occur long before the appearance of the symptoms. Increasing evidence suggests that these stimuli are necessary but not always sufficient to induce the diseases. The murine model of type II collagen emulsified in Freund's incomplete adjuvant (collagen-induced arthritis) to induce rheumatoid arthritis (RA) follows this pattern as some animals do not develop the chronically inflamed phenotype. Considering that in the immune-pineal axis (IPA) theory adrenal-pineal cross-talk adjusts early phases of inflammatory processes, we investigated whether differences in IPA activation could explain why some animals are resistant (RES) while others develop RA. We observed a similar increase in 6-sulfatoxymelatonin (aMT6s) excretion from day 3 to 13 in both RES and RA animals, followed by a significant decrease in RA animals. This pattern of aMT6s excretion positively correlated with plasma corticosterone (CORT) in RES animals. Additionally, RA animals presented a lower aMT6s/CORT ratio than saline-injected or RES animals. Plasmatic levels of tumour necrosis factor were similar in both groups, but interleukin (IL)-1ß and monocyte chemotactic protein 1 (MCP-1) levels were lower in RES compared to RA animals. IL-2 and IL-4 were decreased in RES animals compared to saline-injected animals. The aMT6s/CORT ratio inversely correlated with the paw thickness and the inflammatory score (levels of IL-1ß, MCP-1, IL-2 and IL-4 combined). Thus, adrenocortical-pineal positive interaction is an early defence mechanism for avoiding inflammatory chronification. KEY POINTS: Immune-pineal axis imbalance is observed in early-phase rheumatoid arthritis development. Only resistant animals present a positive association between adrenal and pineal hormones. The 6-sulfatoxymelatonin/corticosterone ratio is decreased in animals that develop rheumatoid arthritis. The inflammatory score combining the levels of nocturnal interleukin (IL)-1ß, monocyte chemotactic protein 1, IL-2 and IL-4 presents a very strong positive correlation with the size of inflammatory lesion. The 6-sulfatoxymelatonin/corticosterone ratio presents a strong negative correlation with the inflammatory score and paw oedema size.

Possible Role of Pineal and Extra-Pineal Melatonin in Surveillance, Immunity, and First-Line Defense.

Melatonin is a highly conserved molecule found in prokaryotes and eukaryotes that acts as the darkness hormone, translating environmental lighting to the whole body, and as a moderator of innate and acquired defense, migration, and cell proliferation processes. This review evaluates the importance of pineal activity in monitoring PAMPs and DAMPs and in mounting an inflammatory response or innate immune response. Activation of the immune-pineal axis, which coordinates the pro-and anti-inflammatory phases of an innate immune response, is described. PAMPs and DAMPs promote the immediate suppression of melatonin production by the pineal gland, which allows leukocyte migration. Monocyte-derived macrophages, important phagocytes of microbes, and cellular debris produce melatonin locally and thereby initiate the anti-inflammatory phase of the acute inflammatory response. The role of locally produced melatonin in organs that directly contact the external environment, such as the skin and the gastrointestinal and respiratory tracts, is also discussed. In this context, as resident macrophages are self-renewing cells, we explore evidence indicating that, besides avoiding overreaction of the immune system, extra-pineal melatonin has a fundamental role in the homeostasis of organs and tissues.

Disrupted nocturnal melatonin in autism: Association with tumor necrosis factor and sleep disturbances.

Sleep disturbances, abnormal melatonin secretion, and increased inflammation are aspects of autism spectrum disorder (ASD) pathophysiology. The present study evaluated the daily urinary 6-sulfatoxymelatonin (aMT6s) excretion profile and the salivary levels of tumor necrosis factor (TNF) and interleukin-6 (IL-6) in 20 controls and 20 ASD participants, as well as correlating these measures with sleep disturbances. Although 60% of ASD participants showed a significant night-time rise in aMT6s excretion, this rise was significantly attenuated, compared to controls (P < .05). The remaining 40% of ASD individuals showed no significant increase in nocturnal aMT6s. ASD individuals showed higher nocturnal levels of saliva TNF, but not IL-6. Dysfunction in the initiation and maintenance of sleep, as indicated by the Sleep Disturbance Scale for Children, correlated with night-time aMT6s excretion (r = -.28, P < .05). Dysfunction in sleep breathing was inversely correlated with aMT6s (r = -.31, P < .05) and positively associated with TNF level (r = .42, P < .01). Overall such data indicate immune-pineal axis activation, with elevated TNF but not IL-6 levels associated with disrupted pineal melatonin release and sleep dysfunction in ASD. It is proposed that circadian dysregulation in ASD is intimately linked to heightened immune-inflammatory activity. Such two-way interactions of the immune-pineal axis may underpin many aspects of ASD pathophysiology, including sleep disturbances, as well as cognitive and behavioral alterations.

Immune-pineal axis protects rat lungs exposed to polluted air.

Environmental pollution in the form of particulate matter <2.5 µm (PM2.5 ) is a major risk factor for diseases such as lung cancer, chronic respiratory infections, and major cardiovascular diseases. Our goal was to show that PM2.5 eliciting a proinflammatory response activates the immune-pineal axis, reducing the pineal synthesis and increasing the extrapineal synthesis of melatonin. Herein, we report that the exposure of rats to polluted air for 6 hours reduced nocturnal plasma melatonin levels and increased lung melatonin levels. Melatonin synthesis in the lung reduced lipid peroxidation and increased PM2.5 engulfment and cell viability by activating high-affinity melatonin receptors. Diesel exhaust particles (DEPs) promoted the synthesis of melatonin in a cultured cell line (RAW 264.7 cells) and rat alveolar macrophages via the expression of the gene encoding for AANAT through a mechanism dependent on activation of the NFκB pathway. Expression of the genes encoding AANAT, MT1, and MT2 was negatively correlated with cellular necroptosis, as disclosed by analysis of Gene Expression Omnibus (GEO) microarray data from the human alveolar macrophages of nonsmoking subjects. The enrichment score for antioxidant genes obtained from lung gene expression data (GTEx) was significantly correlated with the levels of AANAT and MT1 but not the MT2 melatonin receptor. Collectively, these data provide a systemic and mechanistic rationale for coordination of the pineal and extrapineal synthesis of melatonin by a standard damage-associated stimulus, which activates the immune-pineal axis and provides a new framework for understanding the effects of air pollution on lung diseases.

STAT1-NFκB crosstalk triggered by interferon gamma regulates noradrenaline-induced pineal hormonal production.

Melatonin production by pineal glands is modulated by several immune signals. The nuclear translocation of nuclear factor kappa-B (NFκB) homodimers, lacking transactivation domains, once induced by lipopolysaccharide (LPS) or tumor necrosis factor (TNF), inhibits the expression of Aanat gene and the synthesis of noradrenaline (NA)-induced melatonin. Interferon gamma (IFN-γ), on the other hand, increases melatonin synthesis. Furthermore, this cytokine activates the signal transducer as well as the activator of transcription 1 (STAT1) pathway, which was never evaluated as a melatonin synthesis modulator before. Reports demonstrated that IFN-γ might also activate NFκB. The present study evaluated the role of STAT1-NFκB crosstalk triggered by IFN-γ regarding the regulation of NA-induced pineal glands' hormonal production. Moreover, IFN-γ treatment increased NA-induced Aanat transcription, in addition to the synthesis of N-acetylserotonin (NAS) and melatonin. These effects were associated with STAT1 nuclear translocation, confirmed by the co-immunoprecipitation of STAT1 and Aanat promoter. Pharmacological STAT1 enhancement augmented NA-induced Aanat transcription as well as NAS and melatonin production. Additionally, IFN-γ induced the nuclear translocation of RelA-NFκB subunits. The blockade of this pathway prevented IFN-γ effects on the pineal function. The present data show that STAT1 and NFκB crosstalk controls melatonin production through a synergistic mechanism, disclosing a new integrative mechanism regarding pineal hormonal activity control.

ß-Adrenoceptors Trigger Melatonin Synthesis in Phagocytes.

Melatonin (5-methoxy-N-acetylserotonin), the pineal hormone, is also synthesized by immune-competent cells. The pineal hormone signals darkness, while melatonin synthesized on demand by activated macrophages at any hour of the day acts locally, favoring regulatory/tolerant phenotypes. Activation of ß-adrenoceptors in pinealocytes is the main route for triggering melatonin synthesis. However, despite the well-known role of ß-adrenoceptors in the resolution macrophage phenotype (M2), and the relevance of macrophage synthesized melatonin in facilitating phagocytic activity, there is no information regarding whether activation of ß-adrenoceptors would induce melatonin synthesis by monocytes. Here we show that catecholamines stimulate melatonin synthesis in bone marrow-derived dendritic cells and RAW 264.7 macrophages. Activation of ß-adrenoceptors promotes the synthesis of melatonin by stimulating cyclic AMP/protein kinase A (PKA) pathway and by activating the nuclear translocation of NF-κB. Considering the great number of macrophages around sympathetic nerve terminals, and the relevance of this system for maintaining macrophages in stages compatible to low-grade inflammation, our data open the possibility that extra-pineal melatonin acts as an autocrine/paracrine signal in macrophages under resolution or tolerant phenotypes.

Analyses of melatonin, cytokines, and sleep in chronic renal failure.

PURPOSE: Inflammation and oxidative stress are involved in the process of chronic renal failure (CRF). CRF patients show indication of sleep disturbances, and the melatonin rhythm, which modulates sleep, is abnormal in these patients; however, it is still unclear whether inflammation could be related to the blockage of melatonin production and sleep disturbances in this population. The aim of this study was to characterize and correlate sleep, the melatonin rhythm, and the levels of the inflammatory cytokines tumor necrosis factor (TNF) and interleukin (IL)-6 in patients with CRF and controls. METHODS: Sleep was evaluated by the "Sleep Quality Index Pittsburgh" (PSQI) questionnaire, and melatonin and cytokine contents in saliva and blood samples, respectively, were analyzed by ELISA. RESULTS: The CRF group scored higher on the global PSQI, which indicates a lower sleep quality and a higher prevalence of sleep disorders, than the control group. The CRF individuals also showed lower melatonin content than the control groups, both during the day and at night, and lacked rhythmicity in melatonin production. The CRF group also showed higher contents of TNF and IL-6 than the control group and a negative correlation between TNF and melatonin content. CONCLUSION: These results suggest that the sleep disorders observed in the CRF group were probably related to the low production of melatonin observed in this population. The high level of TNF, as previously demonstrated in other pathologies, is probably involved in this blockage of melatonin production in CRF.

Perfil sérico de melatonina, citocinas e cortisol em gestantes com pré-eclâmpsia / Serum profile of melatonin, cytokines and cortisol in pregnant women with preeclampsia

A pré-eclâmpsia (PE) é a maior causa de mortalidade e morbidade materna e perinatal. Sua etiologia permanece desconhecida, o que torna impossível a realização de prevenção primária dessa doença. O entendimento do perfil de substâncias que estão alteradas na PE é de relevância para poder atuar preventivamente. Considerando que vários hormônios envolvidos na resposta imunológica participam da fisiopatologia da PE e que, como demonstrado recentemente, a melatonina tem papel relevante na fisiopatologia da inflamação aguda, nossa hipótese seria que este hormônio poderia também atuar fisiopatologia da PE. OBJETIVOS: avaliar o perfil de citocinas e hormônios no soro de pacientes com PE para estabelecer se o eixo imune-pineal estaria ativado nesta doença. MÉTODOS: Realizamos estudo prospectivo caso-controle, no Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, no período de Outubro de 2010 a Outubro de 2013. O grupo experimental foi formado por pacientes com PE pura no momento do diagnóstico (sem medicação anti-hipertensiva inicial por 24h). Gestantes saudáveis e normotensas, pareadas por idade materna, idade gestacional e paridade, foram selecionadas como controles. Citocinas (TNF, IL-8, IL-6, IL-1beta, IL-4, IFN-y , VEGF , IL-10, IL-12p40, IL-17 e IL-2), cortisol, níveis séricos de melatonina pela manhã (08h-11h) e à noite (23h- 01h), assim como os níveis de 6-sulfatoximelatonina (6-SMT) nos diferentes períodos do dia (bl1:12h-18h, bl2:18h-24h,bl3:24h-06h,bl4:06-12h) foram avaliados por MULTIPLEX e ELISA. A diferença entre os grupos foi avaliada por Two-way ANOVA seguido de pós teste de Bonferroni. Foi considerada significativamente diferente quando a probabilidade da hipótese nula foi rejeitada (p < 0,05). A correlação entre parâmetros foi avaliada por regressão linear simples e teste de Pearson. RESULTADOS: De um total de 31 pacientes inicialmente avaliadas, 14 gestantes com PE e 12 controles foram incluídas. As características das...

Preeclampsia (PE) is a major cause of maternal and perinatal mortality and morbidity. Since its etiology remains unknown, it is impossible to have a primary prevention of the disease. The understanding of the substance profiles that are altered in PE is important to prevent the disease. Considering that many hormones involved in immune response are involved in the physiopathology of PE and that melatonin has a relevant role in the acute inflammatory process, our hypothesis is that this hormone would also be involved in the physiopathology of PE. OBJECTIVES: To analyze the serum profile of cytokines and hormones in pregnant women with PE in order to evaluate if the immune-pineal axis is activated in this disease. METHODS: A prospective case-control study was conducted at the Clinical Hospital USP between October 2010 and October 2013. Only patients with pure PE at the moment of diagnosis (without anti-hypertensive medication for the initial 24h after diagnosis) were included. Normotensive healthy pregnant women that were matched by maternal age, gestational age and parity were included as controls. Cytokines (IL-6, IL-1b, IL-8, TNF and IFNy), cortisol and serum melatonin levels in the morning (08h-11h) and at night (23h-01h), as well as 6-sulfatoximelatonin (6-SMT) levels in different periods of the day (bl1:12h- 18h, bl2:18h-24h, bl3:24h-06h, bl4:06-12h) were measured by MULTIPLEX and ELISA. Differences between groups were analyzed using two-way ANOVA followed by Bonferronis's test. Statistical difference was considered when the null hypothesis was rejected (p < 0.05). Correlations between parameters were analyzed using linear regression and Pearson test. RESULTS: From a total of 31 patients initially evaluated, 14 patients with PE and 12 controls were included. Demographics such as maternal age, parity, gestational age at the dosages, body-mass index were similar in both groups (p > 0.05). TNF and IL-8 levels were higher in the...

Molecular basis for defining the pineal gland and pinealocytes as targets for tumor necrosis factor.

The pineal gland, the gland that translates darkness into an endocrine signal by releasing melatonin at night, is now considered a key player in the mounting of an innate immune response. Tumor necrosis factor (TNF), the first pro-inflammatory cytokine to be released by an inflammatory response, suppresses the translation of the key enzyme of melatonin synthesis (arylalkylamine-N-acetyltransferase, Aanat). Here, we show that TNF receptors of the subtype 1 (TNF-R1) are expressed by astrocytes, microglia, and pinealocytes. We also show that the TNF signaling reduces the level of inhibitory nuclear factor kappa B protein subtype A (NFKBIA), leading to the nuclear translocation of two NFKB dimers, p50/p50, and p50/RelA. The lack of a transactivating domain in the p50/p50 dimer suggests that this dimer is responsible for the repression of Aanat transcription. Meanwhile, p50/RelA promotes the expression of inducible nitric oxide synthase (iNOS) and the production of nitric oxide, which inhibits adrenergically induced melatonin production. Together, these data provide a mechanistic basis for considering pinealocytes a target of TNF and reinforce the idea that the suppression of pineal melatonin is one of the mechanisms involved in mounting an innate immune response.