Interleukin-6 expression by hypothalamic microglia in multiple inflammatory contexts: a systematic review

Interleukin-6 (IL-6) is a unique cytokine that can play both pro- and anti-inflammatory roles depending on the anatomical site and conditions under which it has been induced. Specific neurons of the hypothalamus provide important signals to control food intake and energy expenditure. In individuals with obesity, a microglia-dependent inflammatory response damages the neural circuits responsible for maintaining whole-body energy homeostasis, resulting in a positive energy balance. However, little is known about the role of IL-6 in the regulation of hypothalamic microglia. In this systematic review, we asked what types of conditions and stimuli could modulate microglial IL-6 expression in murine model. We searched the PubMed and Web of Science databases and analyzed 13 articles that evaluated diverse contexts and study models focused on IL-6 expression and microglia activation, including the effects of stress, hypoxia, infection, neonatal overfeeding and nicotine exposure, lipopolysaccharide stimulus, hormones, exercise protocols, and aging. The results presented in this review emphasized the role of injury-like stimuli, under which IL-6 acts as a proinflammatory cytokine, concomitant with marked microglial activation, which drive hypothalamic neuroinflammation. Emerging evidence indicates an important correlation of basal IL-6 levels and microglial function with the maintenance of hypothalamic homeostasis. Advances in our understanding of these different contexts will lead to the development of more specific pharmacological approaches for the management of acute and chronic conditions, like obesity and metabolic diseases, without disturbing the homeostatic functions of IL-6 and microglia in the hypothalamus.2019COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPSem informação2013/07607-

Oral mucositis in pediatric acute lymphoblastic leukemia patients: evaluation of microbiological and hematological factors

To investigate the associations of oral microbiota, leucocytes count, neutrophil count, platelet counts and hemoglobin level, and the severity of oral mucositis in pediatric patients with acute lymphoblastic leukemia (ALL) receiving chemotherapy. 71 prospective patients were included. Analyses of oral microbiota and blood sample were conducted on days 14 (D14) and 56 (D56) of the Brazilian GBTLI-99 treatment protocol. Herpes simplex virus (HSV) identification was performed by PCR followed by DNA sequencing analysis. Bacteria and fungi identification was obtained by standard microbiological culture tests. 103 episodes of mucositis occurred, being 65 at D14 and 38 at D56. Most cases positive for herpes viral DNA sequences were identified as HSV-1. At D14, we found a significant association between the severity of mucositis and presence of HSV-1 (p = 0.0347), Candida spp. (p = 0.0078), and low platelet count (p = 0.0064). At D56, we found a significant association between the severity of mucositis and the presence of HSV-1 (p = 0.0317), previous HSV-1 presence on D14 (p < 0.0001) and neutrophil count (p = 0.0211). Clinical relevance: the identification of risk factors for mucositis in children and adolescents may contribute to the development of new strategies for prevention and/or treatment, reducing the complications associated with this condition. The presence of HSV, platelet count, and Candida spp. presence at D14 of ALL induction treatment is associated with increased severity of mucositis in children and adolescents. At D56 of ALL treatment, mucositis severity was associated with neutrophil count, HSV presence, and previous presence of HSV (at D14).325322330FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPES

High-Fat Diet Induces Apoptosis of Hypothalamic Neurons

Consumption of dietary fats is amongst the most important environmental factors leading to obesity. In rodents, the consumption of fat-rich diets blunts leptin and insulin anorexigenic signaling in the hypothalamus by a mechanism dependent on the in situ activation of inflammation. Since inflammatory signal transduction can lead to the activation of apoptotic signaling pathways, we evaluated the effect of high-fat feeding on the induction of apoptosis of hypothalamic cells. Here, we show that consumption of dietary fats induce apoptosis of neurons and a reduction of synaptic inputs in the arcuate nucleus and lateral hypothalamus. This effect is dependent upon diet composition, and not on caloric intake, since pair-feeding is not sufficient to reduce the expression of apoptotic markers. The presence of an intact TLR4 receptor, protects cells from further apoptotic signals. In diet-induced inflammation of the hypothalamus, TLR4 exerts a dual function, on one side activating pro-inflammatory pathways that play a central role in the development of resistance to leptin and insulin, and on the other side restraining further damage by controlling the apoptotic activity

Hypothalamic S1P/S1PR1 axis controls energy homeostasis

Sphingosine 1-phosphate receptor 1 (S1PR1) is a G-protein-coupled receptor for sphingosine-1-phosphate (S1P) that has a role in many physiological and pathophysiological processes. Here we show that the S1P/S1PR1 signalling pathway in hypothalamic neurons regulates energy homeostasis in rodents. We demonstrate that S1PR1 protein is highly enriched in hypothalamic POMC neurons of rats. Intracerebroventricular injections of the bioactive lipid, S1P, reduce food consumption and increase rat energy expenditure through persistent activation of STAT3 and the melanocortin system. Similarly, the selective disruption of hypothalamic S1PR1 increases food intake and reduces the respiratory exchange ratio. We further show that STAT3 controls S1PR1 expression in neurons via a positive feedback mechanism. Interestingly, several models of obesity and cancer anorexia display an imbalance of hypothalamic S1P/S1PR1/STAT3 axis, whereas pharmacological intervention ameliorates these phenotypes. Taken together, our data demonstrate that the neuronal S1P/S1PR1/STAT3 signalling axis plays a critical role in the control of energy homeostasis in rats

Unsaturated Fatty Acids Revert Diet-Induced Hypothalamic Inflammation in Obesity

Background: In experimental models, hypothalamic inflammation is an early and determining factor in the installation and progression of obesity. Pharmacological and gene-based approaches have proven efficient in restraining inflammation and correcting the obese phenotypes. However, the role of nutrients in the modulation of hypothalamic inflammation is unknown. Methodology/Principal Findings: Here we show that, in a mouse model of diet-induced obesity, partial substitution of the fatty acid component of the diet by flax seed oil (rich in C18:3) or olive oil (rich in C18:1) corrects hypothalamic inflammation, hypothalamic and whole body insulin resistance, and body adiposity. In addition, upon icv injection in obese rats, both v3 and v9 pure fatty acids reduce spontaneous food intake and body mass gain. These effects are accompanied by the reversal of functional and molecular hypothalamic resistance to leptin/insulin and increased POMC and CART expressions. In addition, both, v3 and v9 fatty acids inhibit the AMPK/ACC pathway and increase CPT1 and SCD1 expression in the hypothalamus. Finally, acute hypothalamic injection of v3 and v9 fatty acids activate signal transduction through the recently identified GPR120 unsaturated fatty acid receptor. Conclusions/Significance: Unsaturated fatty acids can act either as nutrients or directly in the hypothalamus, reverting dietinduced inflammation and reducing body adiposity. These data show that, in addition to pharmacological and geneti

PGC-1a modulates interleukin-10 in the liver : interaction with the transcription factors NFkB and C-MAF

Orientador: Licio Augusto VellosoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias MedicasResumo: Insuficiência hepática causada por cirrose decorrente da progressão da esteato-hepatite não alcoólica é hoje uma das principais indicações para transplante hepático no mundo. A ingestão de dietas ricas em lípides é uma das principais causas de esteato-hepatite não alcoólica, e, uma vez estabelecida, poderá ou não evoluir para cirrose, dependendo da ativação de uma resposta inflamatória local. Nem todos os indivíduos que desenvolvem esteatose progridem para a esteato-hepatite. Acredita-se que, dentre os fatores que desempenham papel protetor na progressão para a esteato-hepatite e, por conseguinte, para a cirrose, encontra-se o equilíbrio entre a expressão de citocinas pró- e anti-inflamatórias no fígado. Níveis locais elevados da citocina anti-inflamatória IL-10 reduzem a resistência hepática à insulina e diminuem o risco de desenvolvimento de esteato-hepatite. Em estudos recentes observamos que a inibição da atividade da IL-10 em um modelo animal de esteato-hepatite induzida por dieta contribui para a piora da disfunção hepática. Por outro lado, a redução da expressão do co-ativador de transcrição gênica PGC-1a reverte a esteatose hepática induzida por dieta. Tal reversão é acompanhada pela modulação da expressão de IL-10 e de seu receptor, IL-10R. No presente estudo avaliamos se o PGC-1a?interage com dois fatores de transcrição que participam do controle da expressão de IL-10, c-Maf e NF?Bp50. Para tal utilizamos as técnicas de imunoblot, imunoprecipitação, imunocitoquímica, histologia convencional e imunoprecipitação de cromatina. Os nossos resultados revelam que o PGC-1a?se associa a ambos, c-Maf e p50, após estímulo por ácidos graxos saturados e insaturados. Tal associação ocorre em paralelo ao aumento da expressão de IL-10 e se acompanha da migração de todas as três proteínas de uma localização preferencialmente citosólica para o interior do núcleo de hepatócitos. Além disso, sob estímulo por ácidos graxos, as três proteínas se ligam ao DNA do promotor do gene da IL-10, numa região localizada entre as bases -493 e -254, antes do códon iniciador do gene. Pelo menos a associação de PGC-1a?com p-50 e a indução da expressão de IL-10 por ácidos graxos pode ser inibida pela pré-exposição de hepatócitos ao ácido acetil salicílico, um inibidor da enzima ativadora do NF?B. Portanto, PGC-1a?interage com dois fatores de transcrição e com o DNA da região promotora do gene da IL-10 e emerge como potencial regulador da expressão de IL-10 no fígado.Abstract: Interleukin-10 (IL-10) is an endogenous factor that restrains hepatic insulin resistance in diet-induced steatosis. Reducing IL-10 expression increases pro-inflammatory activity in the steatotic liver and worsens insulin resistance. Because in diet-induced steatosis the transcriptional co-activator PGC-1a plays a central role in the dysfunctional hepatocytic activity, we hypothesized that at least part of PGC-1a activity could be mediated by its effect on the transcriptional control of IL-10 expression. Here, we used immunoblot, real-time PCR, immunocytochemistry and ChIP assay to investigate the role of PGC-1a in the control of IL-10 expression in hepatic cells. First, we show that in the intact steatotic liver, the expressions of IL-10 and PGC-1a are increased. Inhibiting PGC-1a expression by antisense oligonucleotide increases IL-10 expression and reduces the steatotic phenotype. In cultured hepatocytes the treatment with saturated and unsaturated fatty acids, increase IL-10 expression. This is accompanied by increased association of PGC-1a with c-Maf and p50-NF?B, two transcription factors known to modulate IL-10 expression. In addition, following fatty acid treatment PGC-1a, c-Maf and p50- NF?B migrate from the cytosol to the nuclei of hepatocytes and bind to the IL-10 promoter region. Inhibiting NF?B activation with salicylate reduces IL-10 expression and PGC-1a association with p50-NF?B. Thus, PGC-1a emerges as a potential transcriptional regulator of the inflammatory phenomenon taking place in the steatotic liver.MestradoBiologia Estrutural, Celular, Molecular e do DesenvolvimentoMestre em Fisiopatologia Médic

Fractalkine (CX3CL1) participates in the early stages of inflammation in hypothalamus of obese

Orientador: Licio Augusto VellosoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências MédicasResumo: Nas últimas décadas tornou-se claro que indivíduos e animais obesos apresentam um quadro subclínico de inflamação sistêmica. Estudos desenvolvidos em nosso laboratório ao longo dos últimos 10 anos revelaram que a inflamação do hipotálamo está presente em roedores obesos e sua inibição por métodos genéticos e farmacológicos resulta na correção do fenótipo obeso e dos distúrbios metabólicos comumente associados à obesidade. Ácidos graxos saturados de cadeia longa presentes na dieta parecem ser os principais responsáveis pela ativação da resposta inflamatória no hipotálamo. Os primeiros sinais de inflamação podem ser detectados 24 h após a introdução de uma dieta rica neste tipo de gordura. Pelo menos dois mecanismos moleculares foram identificados como potenciais desencadeadores desta resposta inflamatória, sendo eles; a ativação de receptores TLR4, e a indução do estresse de retículo endoplasmático. Durante a exposição precoce a uma dieta rica em gordura saturada, células da micróglia localizadas no hipotálamo, tornam-se ativas e passam a expressar citocinas que, eventualmente, levam a ativação de vias inflamatórias em neurônios da região. A ativação de JNK e IKK em neurônios resulta na indução de resistência hipotalâmica à leptina e insulina, e, subsequentemente na perda do controle coordenado da ingestão alimentar e do gasto calórico. O fato de se observar ativação inflamatória no hipotálamo poucas horas após a exposição aos nutrientes desencadeadores sugere que células da micróglia residentes participem deste processo. Entretanto, com a manutenção da exposição ocorre uma modificação do padrão inflamatório ao longo do tempo, o que sugere que novas células estejam sendo recrutadas. Na primeira etapa deste estudo avaliamos a migração de células monocíticas da medula óssea para o hipotálamo em animais alimentados com dieta rica em gordura saturada. Para tal, transplantes de medula óssea foram realizados para gerar quimeras expressando TLR4 funcional somente em células da medula óssea ou somente em tecidos não originários da medula óssea. A parecença de TLR4 funcional em células de medula óssea foi necessária para expressão completa do fenótipo obeso. Além disso, somente quando TLR4 estava expresso em células da medula óssea, ocorreu infiltração hipotalâmica com células de micróglia oriundas da periferia. Como o recrutamento de células monocíticas da medula óssea para um determinado sítio anatômico depende invariavelmente da expressão de quimiocinas, nós aventamos a hipótese de que nas etapas iniciais da ativação da inflamação hipotalâmica na obesidade alguma(s) quimiocina(s) poderia(m) desempenhar um papel determinante na progressão do processo inflamatório e, consequentemente do fenótipo obeso. Tanto humanos como animais experimentais não consanguíneos apresentam grande variabilidade na expressão fenotípica da obesidade quando expostos a condições ambientais que favoreçam a mesma. Desta forma, buscamos por diferenças no padrão de inflamação do hipotálamo e na expressão de quimiocinas em duas cepas de camundongos com perfis metabólicos e predisposição a obesidade diametralmente opostos, sendo eles: o camundongo Swiss, com grande predisposição a obesidade e diabetes; e, o camundongo Balb-c, virtualmente protegido da obesidade e dos distúrbios metabólicos afins. Identificamos a quimiocina CX3CL1 (fractalkina) como aquela, dentre as avaliadas, com maior distinção de sua expressão no hipotálamo entre as duas cepas de camundongos, encontrando-se mais expressa em Swiss que em Balb-c. Na segunda parte do estudo mostramos que a expressão da fractalkina é induzida em neurônios do hipotálamo frente a um estímulo com nutrientes ricos em ácidos graxos saturados. Em cultura de neurônios, a expressão de fractalkina é induzida preferencialmente por TNF, mas também por palmitato. A inibição da fractalkina no hipotálamo com siRNA protege camundongos Swiss da intolerância à glicose e da obesidade induzidas por dieta rica em gordura saturada, além de reduzir o recrutamento de células monocíticas originárias da medula óssea para o hipotálamo. Assim, concluímos que durante as etapas iniciais da indução da obesidade, células da micróglia residentes ativam a produção de fractalkina por neurônios do hipotálamo a qual desempenha papel importante no recrutamento de novas células monocíticas da medula óssea, que perpetuarão o processo inflamatório do hipotálamo caso a exposição à dieta rica em gordura saturada seja mantida. A fractakina constitui-se, portanto, num dos mais precoces sinalizadores durante a instalação da inflamação hipotalâmica associada à obesidadeAbstract: Studies performed during the last 20 years have shown that obese subjects and experimental models of obesity present a systemic subclinical inflammation. Our group has shown that in experimental obesity the hypothalamus is affected by an inflammatory response and the employment of genetic and pharmacological means to inhibit diet-induced hypothalamic inflammation rescues the obese phenotype and the metabolic disarrangements commonly associated with obesity. Long-chain saturated fatty acids present in the diet are amongst the most important inducers of the hypothalamic inflammation in obesity. The first signs of hypothalamic inflammation can be detected as early as 24 h after the initial exposure to dietary fats. At least two molecular mechanisms have been shown to play a role in the induction of the hypothalamic inflammation in obesity; i.e., activation of TLR4 and induction of endoplasmic reticulum stress. During the early exposition to dietary fats, resident microglia cells are activated and express cytokines that eventually can lead to the induction of inflammatory signaling in the neighboring neurons. The activation of JNK and IKK in neurons results in the induction of hypothalamic resistance to leptin and insulin and, thus, to the loss of the coordinated control of food intake and energy expenditure. As hypothalamic inflammation can be induced a few hours after the initial exposure to dietary fats, it has been suggested that resident microglia are involved in this process. However, as the exposure to dietary fats persists, changes in the pattern of inflammation take place, which may indicate the recruitment of new cells to the inflamed site. In the first part of this study, we evaluate the migration of bone marrow-derived monocytic cells to the hypothalamus of obese animals. Chimera mice were generated by the transplantation of TLR4-expressing bone marrow into TLR4 defective mice and vice-versa. The presence of functional TLR4 in bone marrow-derived cells was required for the complete expression of the obese phenotype. In addition, diet-induced hypothalamic infiltration with bone marrow-derived microglia was obtained only in the presence of functional TLR4 in bone marrow-derived cells. Because the recruitment of bone marrow-derived monocytic cells to a given anatomical site depends invariably on the expression of chemokines, we have raised the hypothesis that, during the initial steps of diet-induced hypothalamic inflammation a (some) chemokine (s) could play an important role in the progression of the inflammatory activity and, consequently, of the obese phenotype. Both humans and outbreed experimental animals display a huge phenotypic variability whenever exposed to environmental conditions that favor obesity. With this concept in mind, we searched for differences in the patterns of hypothalamic inflammation in two strains of mice with different predispositions to obesity and metabolic diseases. The Swiss mice which are prone to obesity, and the Balb-c mice, which are protected from obesity and related metabolic conditions. We identified the chemokine CX3CL1 (fractalkine) as the one, among those that we evaluated, with highest distinction on its hypothalamic expression levels between the two mouse strains; being increased in the hypothalamus of Swiss mice. In the second part of the study we demonstrate that fractakine is induced in hypothalamic neurons by fat-rich diet. In culture, neurons express fractalkine in response to a TNF stimulus preferentially, but also in response to palmitate. The inhibition of hypothalamic expression of fractalkine by siRNA protects mice from glucose intolerance and diet-induced obesity. Moreover, under hypothalamic fractalkine inhibition, diet-induced recruitment of monocytic cells from the bone marrow is severely impaired. We conclude that during the initial steps of diet-induced hypothalamic inflammation, resident microglia cells induce the expression of fractalkine by neighboring neurons, which in turn recruit additional monocytic cells from the bone marrow to maintain the inflammatory process under continuous dietary fatty acid exposure. Thus, fractalkine is one of the earliest signals generated in the hypothalamus during the installation of diet-induced obesityDoutoradoBiologia Estrutural, Celular, Molecular e do DesenvolvimentoDoutora em Fisiopatologia Médic

Breast lipofilling does not pose evidence of chronic inflammation in rats

Laboratory reports on adipose tissue suggest that fat grafting to the breast may pose an oncologic risk. One possible reason for this is the theoretic chronic inflammation due to adipokynes released by grafted white adipose tissue (WAT). Objectives: The aim of this study was to analyze inflammatory activity in lipofilled breast through the use of proinflammatory markers. Methods: Fifty-four paired-breasts of female rats were divided into 4 groups: control, sham, and breasts grafted with either autologous subcutaneous (SC) WAT or autologous omentum (OM). The WAT was prepared through centrifugation, and the grafting was performed with the use of 0.9-mm blunt-tip cannula. The rats were killed 8 weeks postoperatively, and their breasts were harvested for immunohistochemical staining for CD68-expressing macrophages, gene expression (real-time PCR) for monocyte chemoattractant protein 1 (MCP-1), F4/80, Cox-2, and IL-6. Results: The weights of the rats that underwent a procedure differed from those of the unmanipulated control group (P < 0.01). The macrophage counts of CD68 differed only between breasts lipofilled with OM and control (P < 0.01). MCP-1, F4/80, and Cox-2 were similarly expressed among the groups (P = 0.422, P = 0.143, and P = 0.209, respectively). The expression of IL-6 differed between breast samples grafted with SC and OM WAT (P = 0.015), but not between samples of control and OM (P = 0.752), and control and SC (P = 0.056). Conclusions: No inflammation activity was identified in the microenvironment of lipofilled breasts, indicating that chronic inflammation does not seem to be triggered by the breast lipofilling procedure396NP202NP212sem informaçã

Maternal obesity damages the median eminence blood-brain barrier structure and function in the progeny: the beneficial impact of cross-fostering by lean mothers

Maternal dietary habits directly influence offspring health. In this study, we aimed at determining the impact of maternal obesity on BBB integrity. We show that DIO offspring presented a leakier ME–BBB, accompanied by changes in the expression of transcripts encoding for endothelial and tanycytic proteins, as well as of hypothalamic neuropeptides. Breastfeeding in lean dams was sufficient to protect the offspring from ME–BBB disruption, providing a preventive strategy of nutritional intervention during early life