Role of Cytotrophoblast Cells and Placenta-Derived Exosomes in Regulatory B Cell Differentiation and Function during Pregnancy

Pregnancy is a particular physiologic stage during which immune regulation is essential. A successful placentation and subsequent fetal development depend on the delicate balance between moderate pro-inflammatory response and immune tolerance. Findings have pointed out a crucial role for regulatory B cells (Bregs) in establishing an immunomodulatory (IM) environment relevant to pregnancy. In a steady state, Bregs represent 10% of B cells in peripheral blood, a proportion that increases during pregnancy, with the highest rate being observed in post-partum. In the context of pregnancy, Bregs seem to be well positioned to perform the mechanisms that accommodate the growing semi-allogenic fetus and also allow the adequate immune response to pathogen. This chapter discusses the mechanism of action of Bregs during human pregnancy. Also, we will evoke interactions between maternal immune cells and fetal annexes that result in hijacking the naïve B cells to educate and to differentiate them into Bregs

Innate immune cells and T CD4 cells profile during hepatitis B among HIV co-infection Beninese

Background: Worldwide, human immunodeficiency virus (HIV) infection remains a real public health. Hepatitis B virus (HBV) and HIV have the same routes of transmission and shared risk factors and epidemiology similarities. The purpose of this study was to assess the impact of HBV and HIV co-infection on T CD4 cells and innate immune cells.Methods: A cross-sectional and descriptive study was carried among 260 persons living with HIV (PLHIV) admitted and supported with antiviral tri therapy at the national reference center for research and Care of HIV infected person (NRCRC) of the national hospital and university center in Cotonou, Benin. After PLHIV peripheral blood collection, surface hepatitis B antigens (HBsAg) and HIV serology were tested using ELISA (Enzyme linked immuno sorbent assay). White blood cell count and leukocyte formula were performed using flow cytometry. After staining with anti CD4 antibodies, TCD4+ lymphocytes frequency was determined using flow cytometry. Means were calculated using student T test.Results: Of the 260 PLHIV, 10.77% (n=28) were co-infected with HBV. Our data has shown a significant decrease of lymphocytes among HIV and HBV co-infected persons and a very significant increase in immune innate cells including eosinophils, polynuclear basophils and monocytes, suggesting an important role of innate immune cells during HIV and HBV coinfection.Conclusion: HIV and HBV coinfection results in hyperinflammatory response associated with viral clearance. How this hyperinflammatory response is mounted was still unclear. More data are needed for better management of HIV and HBV co-infection

Rôles de la cavéoline-1 et des antioxydants dans l'homéostasie des cellules thyroïdiennes et des cellules musculaires squelettiques

H2O2, produced by dual oxidases (Duox), is an absolute requirement for thyroid hormone synthesis. To avoid the toxic effect of H2O2, the best protection of the thyroid cell is the localization of the H2O2 production site outside the cell, at the interface with the colloid. That has been recently reinforced by the concept of “thyroxisome”, the unit of thyroid hormone synthesis. The thyroxisome is a multimeric complex, made of at least TPO and Duox, and it permits to restrain the iodination process at the apical pole of the cell. In the first part of this work, we hypothesize that caveolin-1 could be implicated in the thyroxisome formation. Indeed, caveolin-1, expressed at the apical pole of thyrocytes and regulated by TSH, is well known in different cell types to be implicated in the compartmentalization of a variety of cell processes. In caveolin-1 KO mice, we show that thyroglobulin (Tg), Duox, and TPO transport is impaired, and that these proteins are localized in the cytoplasm. This thyroxisome disruption leads to thyroid alterations, 50% of the follicle lumina being empty. The localization of I127, iodinated Tg, and TPO inside the cell indicates that the iodination process occurs in the cytoplasm rather than in the colloid. In the second part of this work, we studied how the loss of a component of the thyroid hormone synthesis machinery could have an effect on the thyroid cell homeostasis. Indeed, in order to maintain an appropriate location of iodination process, all partners must be present at the proper place. An important component is iodide which is transported across the apical membrane probably by pendrin. Pendred disease is characterized by mutation in Pendred gene leading to deficiency in pendrin. We show that the Pendred thyroid contains numerous altered follicles without iodinated Tg and T4, but with an intracellular localization of Duox, TPO and T4 associated with a loss of caveolin-1, while others show a normal iodination. We conclude that the loss of pendrin leads to thyroxisome disruption. In thyroids of both KO caveolin-1 mice and Pendred patient, the intracellular iodination is associated with high oxidative stress (OS), and increased expression of antioxidant enzymes like peroxiredoxins (PRDXs) and catalase. This high OS leads to apoptosis, partially compensated by increased proliferation. This association of increased proliferation and absence of caveolin-1 expression confirms the negative role played by caveolin-1 on thyrocytes proliferation. If apoptosis rate becomes more important than the proliferation one, the follicular destruction increases and induces severe hypothyroidism. In the third part of this work, we analyzed the effect of a chronic TSH stimulation on thyroid cell homeostasis. In Graves’ disease, while the hyperstimulation of TSH receptor (TSHR) by autoantibodies induces an overexpression, but with a correct localization of thyroxisome components, the thyroxisome integrity is maintained. This induces an increased hormonal synthesis associated with higher OS which remains yet not toxic, but correctly compensated by antioxidants. The Graves’ disease is often associated with a thyroid ophthalmopathy (TAO) induced by TSHR autoantibodies. Indeed TSHR is expressed by both thyrocytes and orbital fibroblasts. Interactions between these fibroblasts and infiltrating lymphocytes induce fibrosis and adipogenesis leading finally to dissociation of skeletal muscle cells. In this work, we show that muscle cells as well as adipocytes coming from TAO patients undergo OS, compensated by increased PRDXs and catalase expression, or leading to apoptosis. We show also that in case of TAO, the expression of adiponectin by muscular cells is increased as well as its regulator, PPARgamma. Thus, we suggest that adiponectin could play a role as an antioxidant. In conclusion, in order to maintain the thyroid cell homeostasis, a strict localization of H2O2 production within the thyroxisome, most likely brought together by caveolin-1, is absolutely required. To keep cell homeostasis, all proteins participating in hormone synthesis must be active and correctly localized in order to avoid cytoplasmic accumulation of iodide that may lead to OS and cell apoptosis. These conclusions obtained by our study on KO caveolin-1 mice and on Pendred thyroid are reinforced by the study of Graves’ disease where the chronically stimulated iodination machinery, as well as caveolin-1, is correctly localized. In this case, the OS is not toxic but well compensated by antioxidants. The increased adiponectin levels observed in Graves’ disease and TAO could be implicated in this antioxidant defense.La synthèse des hormones thyroïdiennes requiert la production d’H2O2 par les dual oxydases (Duox). L’H2O2 pouvant être toxique, les thyrocytes se protègent en localisant sa production hors du cytoplasme à l’interface apicale avec le colloïde. L’existence d’une telle forme de protection a été récemment renforcée par le concept du « thyroxysome » comme unité de synthèse hormonale formée par l’assemblage des enzymes d’iodation en un complexe multi-protéique au pôle apical. L’avantage de ce modèle est la restriction de la production d’H2O2 là où elle est consommée, ce qui permet de maintenir l’homéostasie cellulaire. Dans la première partie de ce travail, nous avons postulé que la cavéoline-1 pouvait intervenir dans l’assemblage des composantes du thyroxysome. En effet, la cavéoline-1 est une protéine connue comme étant impliquée dans la compartimentation de divers processus cellulaires. Elle est localisée au pôle apical des thyrocytes humains et régulée par la TSH. En utilisant le modèle de souris dont le gène de la cavéoline-1 a été inactivé (Cav-1 -/-), nous avons montré que l’absence de cavéoline-1 entraîne un défaut de transport de la thyroglobuline (Tg), de Duox et de la thyroperoxydase (TPO) au pôle apical des thyrocytes. La rupture du thyroxysome entraîne des altérations phénotypiques de la thyroïde, 50% des follicules présentant des lumières folliculaires vides de Tg et de Tg iodée. L’iodation y est intracellulaire comme le démontre la localisation cytoplasmique d’iode127 et de Tg iodée, ainsi que de TPO et Duox dont l’expression est accrue. Dans la deuxième partie de ce travail, nous avons étudié comment le dérèglement d’une des composantes nécessaire à la synthèse hormonale pouvait affecter l’homéostasie des cellules thyroïdiennes. En effet, le maintien du lieu physiologique d’iodation implique aussi que toutes les protéines intervenant dans la synthèse hormonale soient activées. Une étape importante de la synthèse des hormones thyroïdiennes est la concentration de l’iodure, à partir du plasma sanguin vers le colloïde. Un transporteur d’iodure au pôle apical est la pendrine, dont la déficience caractérise le syndrome de Pendred. Nous avons analysé la thyroïde d’une patiente atteinte de ce syndrome et ayant développé une surdité bilatérale et un goitre avec hypothyroïdie sévère. La défaillance du transport apical d’iodure entraîne des altérations folliculaires avec absence de Tg iodée et de T4 dans le colloïde, ainsi qu’une iodation intracellulaire qui fait suite à la rupture du thyroxysome, comme le démontrent la surexpression cytoplasmique de Duox et TPO et l’absence de cavéoline-1. Que ce soit dans le syndrome de Pendred ou dans le modèle des souris Cav1 -/-, l’iodation intracellulaire est associée à un stress oxydatif (SO) qui est compensé par la surexpression des protéines antioxydantes comme les peroxyrédoxines (PRDX) et la catalase. Ce SO important conduit à l’apoptose des thyrocytes, qui elle-même peut être compensée par une augmentation de la prolifération. Nous avons ainsi confirmé que la cavéoline-1 régule négativement la prolifération des thyrocytes. Si l’apoptose excède cette capacité de prolifération, la destruction folliculaire devient plus importante et est responsable de l’hypothyroïdie sévère. Dans une troisième partie de cette thèse, nous avons analysé l’effet d’une stimulation chronique par la TSH sur l’homéostasie thyroïdienne. Dans la maladie de Graves, l’hyperstimulation des thyrocytes par des autoanticorps dirigés contre le récepteur de la TSH (RTSH) n’altère pas le thyroxysome dont les composantes, y compris la cavéoline-1, sont surexprimées mais bien localisées. Le SO est bien compensé par les défenses antioxydantes. Il n’y a pas de toxicité cellulaire, mais bien une augmentation de la synthèse hormonale entrainant une hyperthyroïdie. La thyroïdite de Graves est souvent associée à une ophtalmopathie thyroïdienne (TAO) due à la réaction immunitaire face essentiellement au RTSH qui est exprimé par les fibroblastes orbitaires, comme par les thyrocytes. Les multiples interactions entre ces fibroblastes et les lymphocytes infiltrant l’orbite amènent à la fibrose et à l’adipogenèse qui dissocient les cellules musculaires squelettiques. Nous avons montré que les cellules musculaires, tout comme les adipocytes de la graisse orbitaire, subissent un SO qui peut être compensé pas la surexpression des peroxyrédoxines et de la catalase, ou mener à l’apoptose. Nous avons démontré qu’en cas de TAO, les cellules musculaires squelettiques surexpriment l’adiponectine et son régulateur, PPARgamma, et nous suggérons que l’adiponectine pourrait y avoir un rôle antioxydant. En conclusion, le maintien de l’homéostasie des cellules thyroïdiennes nécessite une stricte localisation de la production d’H2O2 dans le thyroxysome, compartiment d’iodation extracellulaire vraisemblablement assemblé par la cavéoline-1. Le maintien de l’homéostasie implique aussi que toutes les protéines intervenant dans la synthèse hormonale soient actives et correctement localisées afin d’éviter l’accumulation d’iode dans le cytoplasme entraînant un SO et l’apoptose. Notre étude de la maladie de Graves renforce ces conclusions. En effet, la machinerie d’iodation y est stimulée, mais correctement localisée, tout comme la cavéoline-1. Le SO n’y est pas toxique, compensé par les antioxydants. L’augmentation de l’adiponectine en cas de maladie de Graves et TAO pourrait être impliquée dans la défense antioxydante.(SBIM 3) -- UCL, 201

Induction of adiponectin in skeletal muscle of type 2 diabetic mice: In vivo and in vitro studies.

AIMS/HYPOTHESIS: Adiponectin is an adipokine that exhibits insulin-sensitising, fat-burning and anti-inflammatory properties as well as modulatory effects on oxidative stress. We examined whether adiponectin could be induced in a non-adipose tissue, skeletal muscle, in response to metabolic or oxidative aggression both in vivo (in a murine model of type 2 diabetes) and in vitro. METHODS: Obese and diabetic ob/ob mice were used and compared with lean littermates. Some obese mice were treated with the antioxidant probucol for 3 weeks. At the end of the experiment, blood was sampled and tibialis anterior muscles were collected for mRNA measurement and immunohistochemistry. Additional in vitro experiments were performed on C2C12 myotubes cultured for up to 48 h. RESULTS: In spite of hypoadiponectinaemia, Adipoq mRNA levels were markedly increased in the skeletal muscle of ob/ob mice and correlated with systemic oxidative stress. Adipoq upregulation was shown in laser-microdissected myocytes of obese mice. Concomitantly, immunoreactivity for adiponectin was enhanced in obese muscle fibres together with lipid infiltration and local markers of oxidative stress. In cultured C2C12 myotubes, a triglyceride mix and reactive oxygen species producers (H2O2 or a lipoperoxidation end-product) upregulated Adipoq expression and adiponectin production. This effect was reversed by an antioxidant. Finally, treatment of obese mice with probucol also attenuated upregulation in muscle. CONCLUSIONS/INTERPRETATION: The paradoxical upregulation of adiponectin in muscle of obese and diabetic mice may result from lipotoxicity and related oxidative stress. This unexpected finding could be viewed as a local protection to counteract ectopic fat deposition and oxidative damage

Visualisation of thyroid hormone synthesis by ion imaging

The main function of the thyroid gland is to make hormones, T4 and T3, which are essential for the regulation of metabolic processes throughout the body. Caveolae harbour is the key enzymes involved in this iodide organification. The analyses of thyroids from normal mice and caveolin-1 Knockout mice (mice deficient in caveolin) have been performed using the SIMS imaging. In the thyroid of control mice, the epithelium is homogeneous and iodine (I-127) is observed in the follicle lumen. In Knockout mice, we observe an accumulation of intracellular vesicles and apoptotic nuclei resulting from oxidative stress due to H2O2 overproduction also inducing apical lesions of the thyrocytes, at the site of iodine organification and H2O2 generation. We also observe in the Knockout mice an accumulation of I-127 in the cellular cytoplasm and an absence of the iodine in some follicular lumina, indicating a problem at the level of iodine organification. Crown Copyright (C) 2008 Published by Elsevier B. V. All rights reserved

Adiponectin and skeletal muscle: pathophysiological implications in metabolic stress

Upregulation of muscular adiponectin could act as a local protective mechanism to counteract cellular damage in obesity by weakening inflammation, oxidative stress, and apoptosis. To test this hypothesis, adiponectin-knockout (KO) and wild-type (WT) mice were fed a Western diet (WD). WT mice under WD conditions displayed 63% higher adiponectin expression in myocytes than those under standard laboratory diet (SLD) conditions (P = 0.011). WD-fed KO mice exhibited approximately threefold larger myocyte degeneration than WT mice (P = 0.003). Even under SLD conditions, myotubes of KO mice displayed already moderate immunolabeling for markers of oxidative stress (peroxiredoxin-3/5) and for a lipid peroxidation product (hydroxynonenal). Expression of tumor necrosis factor-α (TNF-α) and caspase-6, a marker of apoptosis, was also present. After WD challenge, immunoreactivity for these markers was strong in muscle of KO mice, although it was detected to a lesser extent in WT mice. Activation of NF-κB and caspase-6 doubled in myocytes of WD-fed KO mice when compared to WT mice (P < 0.001). Furthermore, muscle electrotransfer of the adiponectin gene prevented these abnormalities in WD-fed KO mice. Finally, gene abrogation of the adiponectin receptor 1 (AdipoR1) by siRNA recapitulated a pro-inflammatory state in C2C12 myotubes. Thus, upregulation of muscular adiponectin may be triggered by obesity and be crucial locally to counteract oxidative stress, inflammation, and apoptosis. These effects operate in an autocrine/paracrine manner via AdipoR1 and down-regulation of NF-κB signaling

Local induction of adiponectin reduces lipopolysaccharide-triggered skeletal muscle damage

Adiponectin (ApN) exhibits metabolic and antiinflammatory properties. This hormone is exclusively secreted by adipocytes under normal conditions. We have shown that ApN was induced in tibialis anterior muscle of mice injected with lipopolysaccharide (LPS) and in C2C12 myotubes cultured with proinflammatory cytokines. We hypothesized that muscle ApN could be a local protective mechanism to counteract excessive inflammatory reaction and oxidative damage. To test this paradigm, we examined whether muscles of ApN-knockout (KO) mice exhibit a higher degree of oxidative stress and apoptosis than wild-type mice when challenged by ip LPS and whether these abnormalities may be corrected by local administration of ApN. Eventually we investigated the effects of ApN in vitro. When compared with wild-type mice, ApN-KO mice exhibited myocyte degenerescence, especially after LPS. Myocytes of ApN-KO mice also displayed much stronger immunolabeling for markers of oxidative stress (peroxiredoxin-3/5 and heme oxygenase-1) as well as for a lipid peroxidation product (hydroxynonenal). Expression of TNF-alpha, caspase-6, a marker of apoptosis, and nuclear factor-kappaB was enhanced as well. Eventually muscle electrotransfer of the ApN gene, which did not induce any rise of systemic ApN, corrected all these abnormalities in LPS-injected ApN-KO mice. Likewise, ApN attenuated LPS-induced production of proinflammatory cytokines and activation of nuclear factor-kappaB in C2C12 cells. Thus, induction of ApN into skeletal muscle in response to an inflammatory aggression appears to be a crucial mechanism to counteract in an autocrine or paracrine fashion excessive inflammatory damage, oxidative stress, and subsequent apoptosis