Effects of fish oil on the neuro-endocrine responses to an endotoxin challenge in healthy volunteers

Résumé Introduction et hypothèse : Certains acides gras polyinsaturés de type n-3 PUFA, qui sont contenus dans l'huile de poisson, exercent des effets non-énergétiques (fluidité des membranes cellulaires, métabolisme énergétique et prostanoïdes, régulation génique de la réponse inflammatoire). Les mécanismes de la modulation de cette dernière sont encore mal connus. L'administration d'endotoxine (LPS) induit chez les volontaires sains une affection inflammatoire aiguë, comparable à un état grippal, associé à des modifications métaboliques et inflammatoires transitoires, similaires au sepsis. Ce modèle est utilisé de longue date pour l'investigation clinique expérimentale. Cette étude examine les effets d'une supplémentation orale d'huile de poisson sur la réponse inflammatoire (systémique et endocrinienne) de sujets sains soumis à une injection d'endotoxine. L'hypothèse était que la supplémentation d'huile de poisson réduirait les réponses physiologiques à l'endotoxine. Méthodes : Quinze volontaires masculins (âge 26.0±3.1 ans) ont participé à une étude randomisée, contrôlée. Les sujets sont désignés au hasard à recevoir ou non une supplémentation orale : 7.2 g d'huile de poisson par jour correspondant à un apport de 1.1 g/jour d'acides gras 20:5 (n-3, acide écosapentaénoïque) et 0.7 g/jour de 22:6 (n-3, acide docosahexaénoïque). Chaque sujet est investigué deux fois dans des conditions identiques : une fois il reçoit une injection de 2 ng par kg poids corporel de LPS intraveineuse, l'autre fois une injection de placebo. Les variables suivantes sont relevées avant l'intervention et durant les 360 min qui suivent l'injection :signes vitaux, dépense énergétique (EE) et utilisation nette des substrats (calorimétrie indirecte, cinétique du glucose (isotopes stables), taux plasmatique des triglycérides et FFA, du glucose, ainsi que des cytokines et hormones de stress (ACTH, cortisol, Adré, Nor-Adré). Analyses et statistiques :moyennes, déviations standards, analyse de variance (one way, test de Scheffé), différences significatives entre les groupes pour une valeur de p < 0.05. Résultats :L'injection de LPS provoque une augmentation de la température, de la fréquence cardiaque, de la dépense d'énergie et de l'oxydation nette des lipides. On observe une élévation des taux plasmatiques de TNF-a et IL-6, de la glycémie, ainsi qu'une élévation transitoire des concentrations plasmatiques des hormones de stress ACTH, cortisol, adrénaline et noradrénaline. L'huile de poisson atténue significativement la fièvre, la réponse neuro-endocrinienne (ACTH et cortisol) et sympathique (baisse de la noradrénaline plasmatique). Par contre, les taux des cytokines ne sont pas influencés par la supplémentation d'huile de poisson. Conclusion : La supplémentation d'huile de poisson atténue la réponse physiologique à l'endotoxine chez le sujet sain, en particulier la fièvre et la réponse endocrinienne, sans influencer la production des cytokines. Ces résultats soutiennent l'hypothèse que les effets bénéfiques de l'huile de poisson sont principalement caractérisés au niveau du système nerveux central, par des mécanismes non-inflammatoires qui restent encore à élucider.

Glucose sensing and the pathogenesis of obesity and type 2 diabetes.

The control of body weight and of blood glucose concentrations depends on the exquisite coordination of the function of several organs and tissues, in particular the liver, muscle and fat. These organs and tissues have major roles in the use and storage of nutrients in the form of glycogen or triglycerides and in the release of glucose or free fatty acids into the blood, in periods of metabolic needs. These mechanisms are tightly regulated by hormonal and nervous signals, which are generated by specialized cells that detect variations in blood glucose or lipid concentrations. The hormones insulin and glucagon not only regulate glycemic levels through their action on these organs and the sympathetic and parasympathetic branches of the autonomic nervous system, which are activated by glucose or lipid sensors, but also modulate pancreatic hormone secretion and liver, muscle and fat glucose and lipid metabolism. Other signaling molecules, such as the adipocyte hormones leptin and adiponectin, have circulating plasma concentrations that reflect the level of fat stored in adipocytes. These signals are integrated at the level of the hypothalamus by the melanocortin pathway, which produces orexigenic and anorexigenic neuropeptides to control feeding behavior, energy expenditure and glucose homeostasis. Work from several laboratories, including ours, has explored the physiological role of glucose as a signal that regulates these homeostatic processes and has tested the hypothesis that the mechanism of glucose sensing that controls insulin secretion by the pancreatic beta-cells is also used by other cell types. I discuss here evidence for these mechanisms, how they integrate signals from other nutrients such as lipids and how their deregulation may initiate metabolic diseases.

Ageing with HIV: medication use and risk for potential drug-drug interactions.

OBJECTIVES: To compare the use of co-medication, the potential drug-drug interactions (PDDIs) and the effect on antiretroviral therapy (ART) tolerability and efficacy in HIV-infected individuals according to age, ≥ 50 years or <50 years. METHODS: All ART-treated participants were prospectively included once during a follow-up visit of the Swiss HIV Cohort Study. Information on any current medication was obtained by participant self-report and medical prescription history. The complete treatment was subsequently screened for PDDIs using a customized version of the Liverpool drug interaction database. RESULTS: Drug prescriptions were analysed for 1497 HIV-infected individuals: 477 age ≥ 50 and 1020 age <50. Older patients were more likely to receive one or more co-medications compared with younger patients (82% versus 61%; P < 0.001) and thus had more frequent PDDIs (51% versus 35%; P < 0.001). Furthermore, older patients tended to use a higher number of co-medications and certain therapeutic drug classes more often, such as cardiovascular drugs (53% versus 19%; P < 0.001), gastrointestinal medications (10% versus 6%; P = 0.004) and hormonal agents (6% versus 3%; P = 0.04). PDDIs with ART occurred mainly with cardiovascular drugs (27%), CNS agents (22%) and methadone (6%) in older patients and with CNS agents (27%), methadone (15%) and cardiovascular drugs (11%) in younger patients. The response to ART did not differ between the two groups. CONCLUSIONS: The risk for PDDIs with ART increased in older patients who take more drugs than their younger HIV-infected counterparts. However, medication use in older and younger patients did not differ in terms of effect on antiretroviral tolerability and response.

Immunolocalization of neuropeptide Y in human pancreatic endocrine tumors.

Neuropeptide Y (NPY) is a 36 amino acid peptide known to inhibit glucose-stimulated insulin secretion. NPY has recently been shown to be synthetized within rat islets of Langerhans and to be secreted in a differentiated rat insulin-secreting cell line, and as to this date the localization of NPY in human endocrine pancreas has not been reported. As NPY shares high amino acid sequence homology with peptide YY (PYY) and pancreatic polypeptide (PP), the polyclonal antibodies raised against these peptides often cross-react with each other. To demonstrate the presence of NPY in the human endocrine pancreas, we used a highly specific monoclonal antibody raised against NPY and another against its C-flanking peptide (CPON). We studied three cases of hyperplasia of Langerhans islets and 11 cases of endocrine tumors of the pancreas. NPY and CPON were detected in all three cases of hyperplasia. For the 11 pancreatic tumors, five and nine of the tumors were positive for the antibodies NPY and CPON, respectively. The two negative tumors for CPON immunoreactivity were differentiated insulinomas, which showed no evidence of other hormonal secretion. In normal Langerhans islet, NPY and CPON immunoreactivities were colocalized in glucagon-producing cells (alpha-cells) and in a few insulin-secreting cell (beta-cells).(ABSTRACT TRUNCATED AT 250 WORDS)

Hormonal and metabolic changes following severe head injury or noncranial injury.

In order to evaluate the effect of head injury in severely traumatized patients on the response of plasma cortisol, glucagon, insulin, glucose, and FFA as well as urinary N and catecholamines excretions, 36 patients were prospectively studied over 5 consecutive days following injury. They were divided into three groups: group I, severe isolated head injury (n = 14); group II, multiple injury combined with severe head injury (n = 12); group III multiple injury without head injury (n = 10). The results demonstrate similar hormonal and metabolic changes between these three groups of patients, characterized by elevated urinary adrenaline, noradrenaline excretion, increased cortisol, glucagon, insulin plasma levels throughout the study and elevated N urinary excretion with strongly negative N balances during the first 5 days postinjury. A significant correlation was observed between N intake and 5 day cumulated N balance (r = 0.63, p less than 0.001). In addition, N balance was negatively correlated with urinary excretion of adrenaline (r = -0.47, p less than 0.01) and noradrenaline (r = -0.44, p less than 0.05) as well as plasma levels of glucagon (r = -0.44, p less than 0.05). Isolated severe head injury seems to induce a full response in the secretion of the catabolic counterregulatory hormones comparable to that encountered in patients with multiple injury and associated with a marked increase in protein catabolism; additional noncranial major injury does not seem to enhance these responses.

Expression analyses of three members of the AtPHO1 family reveal differential interactions between signaling pathways involved in phosphate deficiency and the responses to auxin, cytokinin, and abscisic acid.

The PHO1 protein is involved in loading inorganic phosphate (Pi) to the root xylem. Ten genes homologous to AtPHO1 are present in the Arabidopsis thaliana (L.) Heyn genome. From this gene family, transcript levels of only AtPHO1, AtPHO1;H1 and AtPHO1;H10 were increased by Pi-deficiency. While the up-regulation of AtPHO1;H1 and AtPHO1;H10 by Pi deficiency followed the same rapid kinetics and was dependent on the PHR1 transcription factor, phosphite only strongly suppressed the expression of AtPHO1;H1 and had a minor effect on AtPHO1;H10. Addition of sucrose was found to increase transcript levels of both AtPHO1 and AtPHO1;H1 in Pi-sufficient or Pi-deficient plants, but to suppress AtPHO1:H10 under the same conditions. Treatments of plants with auxin or cytokinin had contrasting effect depending on the gene and on the Pi status of the plants. Thus, while both hormones down-regulated expression of AtPHO1 independently of the plant Pi status, auxin and cytokinin up-regulated AtPHO1;H1 and AtPHO1;H10 expression in Pi-sufficient plants and down-regulated expression in Pi-deficient plants. Treatments with abscisic acid inhibited AtPHO1 and AtPHO1;H1 expression in both Pi-sufficient and Pi-deficient plants, but increased AtPHO1;H10 expression under the same conditions. The inhibition of expression by abscisic acid of AtPHO1 and AtPHO1;H1, and of the Pi-starvation responsive genes AtPHT1;1 and AtIPS1, was dependant on the ABI1 type 2C protein phosphatase. These results reveal that various levels of cross talk between the signal transduction pathways to Pi, sucrose and phytohormones are involved in the regulation of expression of the three AtPHO1 homologues.

A common ancestor DNA motif for invertebrate and vertebrate hormone response elements.

The ecdysone-responsive DNA sequence of the Drosophila hsp27 gene promoter contains four direct and inverted repeats reminiscent of those that compose the vertebrate palindromic estrogen response element (ERE) and the thyroid hormone/retinoic acid response element (TRE/RRE). Interestingly, a 3 bp substitution in the wild-type Hsp27 ecdysone response element (EcdRE) increases both its similarity with the vertebrate ERE and TRE/RRE and its capacity to confer ecdysone responsiveness to a heterologous promoter. Remarkably, increasing the spacing between the inverted repeats of this strong EcdRE by two nucleotides converts it into an ERE. Inversely, decreasing the spacing between the two inverted repeats of the vertebrate consensus palindromic ERE, from three to one nucleotide, converts it into a functional EcdRE. Thus, the only difference between an invertebrate EcdRE and a vertebrate palindromic ERE or TRE/RRE is in the spacing between the conserved inverted repeated motifs forming these palindromic HREs. The finding that the sequence motif 5'-GGTCA-3' present in the vertebrate ERE and TRE/RRE is also a functionally important characteristic of an invertebrate HRE, suggests that a common ancestor regulatory DNA sequence gave rise to all HREs known so far. We discuss the possibility that this progenitor motif is the GGTCA sequence.

Role of the inflammasome in murine experimental models of arthritis

Summary : The purpose of this study was to investigate the role of the inflammasome in human and experimental murine models (such as ΑΙΑ and K/BxN) of rheumatoid arthritis (RA)RA, affecting 1% of the population is the most frequent inflammatory disease characterized by synovial hyperplasia and cartilage and bone erosion, leading to joint destruction. In general, women are 3 times more affected by RA suggesting a role of estrogen in this disease. The inflammasome is a multiproteic complex triggering the activation of caspase-1 leading to the activation of IL-1 β, an important pro-inflammatory cytokine implicated in arthritis. The inflammasome has been implicated in several inflammatory diseases and particularly in gout. To highlight a possible role of the inflammasome in murine arthritis, we obtained ASC, caspase-1 and NALP3 +/+ and -/- littermate mice to perform ΑΙΑ and K/BxN arthritis. NALP3 -/- and caspase-1 -/- mice were as arthritic as wild type littermate mice in both ΑΙΑ and K/BxN models implicating that the NALP3 inflammasome is not involved in experimental arthritis. By contrast, ΑΙΑ severity was significantly diminished in ASC- deficient male and female mice, and in the K/BxN model, in ASC-deficient female mice. These results were supported by histological scoring and acute phase protein serum amyloid A (SAA) levels that were equivalent between NALP+/+ and NALP3-/- mice and diminished in ASC -/- mice. In ΑΙΑ and K/BxN murine experimental models, we observed a sexdependent phenotype. We studied the role of estradiol in both the ALA and the K/BxN models. Castrated female or male ASC -/- mice that received estradiol had a decreased arthritis severity. This implies a protective role of estrogen in the absence of ASC. In the ΑΙΑ model, proliferation assay were performed using splenocytes from mBSA- immunized ASC +/+ and -/- mice. The mBSA-induced proliferation was significantly lower in ASC-/- splenocytes. Moreover the CD3-specific proliferation of purified splenic Τ cells was significantly lower in ASC-/- cells. Finally, Τ cells from ASC-/- mice produced significantly decreased levels of IFN-gamma associated with increased levels of IL-10. These results imply a possible role of ASC in the TCR-signaling pathway and Τ cell cytokine production. In parallel the expression of the different inflammasome components were analyzed in biopsies from rheumatoid arthritis (RA) and osteoarthritis (OA) patiens. The expression of the 14 different NALPs, their effector protein ASC, and caspase-1 and -5 was readily measurable by RT-PCR in a similar proportion in RA and OA synovial samples, with the exception of NALP-5 and NALP-13, which weren't found in samples from either disease. The corresponding NALP1, -3, -12 and ASC proteins were expressed at similar levels in both OA and RA biopsies, as determined by immunohistochemistry and Western-blot analysis. By contrast, caspase-1 levels were significantly enhanced in RA synovial tissues compared to those from OA patients. NALP-1, -2, -3, -10, -12 and -14, as well as ASC, caspase-1, and -5 were detected in RNA from unstimulated and stimulated RA synoviocytes. In FLS, only ASC and caspase-1 were expressed at the protein level. NALP1, 3 and 12 were not detected. However, upon stimulation, no secreted IL-Ιβ was detectable in either RA or in OA synoviocytes culture medium. Résumé : Le but de ce projet était d'étudier le rôle de l'inflammasome dans des modèles expérimentaux d'arthrite tels que les modèles ΑΙΑ et K/BxN ainsi que dans la polyarthrite humaine (RA). La polyarthrite est une maladie inflammatoire très fréquente avec 1 % de la population affectée et touche 3 fois plus les femmes que les hommes, suggérant un rôle des hormones sexuelles dans cette pathologie. L'inflammasome est un complexe multiprotéique qui permet l'activation de la caspase-1, une cystéine protéase qui va ensuite cliver et activer rinterleukine-ΐβ (IL-Ιβ). L'inflammasome a été impliqué ces dernières années dans de nombreuses maladies inflammatoires notamment dans la goutte. Pour mettre en évidence un éventuel rôle de l'inflammasome dans l'arthrite expérimentale nous avons obtenu des souris déficientes pour certains des composants de l'inflammasome tels que ASC, NALP3 et caspase-1. Les souris NALP3 déficientes et caspase-1 déficientes sont aussi arthritiques que les souris wild type correspondantes que ce soit dans le modèle ΑΙΑ ou K/BxN. Par contre les souris mâles et femelles ASC-déficientes sont moins arthritiques que les souris +/+ correspondantes dans le modèle ΑΙΑ. Dans le modèle KRN, le même phénotype (diminution de la sévérité de l'arthrite) est observé uniquement chez les femelles ASC-/- Ce phénotype est corrélé avec l'histologie ainsi qu'avec le dosage du serum amyloid A (SAA) qui reflète l'inflammation systémique et qui est diminué chez les souris ASC-déficientes. Nous avons ensuite étudié le rôle de Γ estradiol (une des formes active des estrogènes) dans les modèles K/BxN et ΑΙΑ. Les souris castrées maies ou femelles déficientes pour ASC ayant reçu de l'estradiol ont une arthrite moins sévère ce qui implique que les estradiol ont un effet protecteur en l'absence de ASC. Dans le modèle ΑΙΑ, nous nous sommes aussi intéressés à la réponse immune. Des tests de prolifération ont été effectués sur des splénocytes en présence de mBSA (qui est l'antigène utilisé dans le modèle ΑΙΑ). Les splénocytes ASC -/- ont une proliferation qui est diminuée en présence de l'antigène. De plus la proliferation de cellules Τ spléniques purifiées en présence d'anti-CD3 est diminuée chez les cellules Τ ASC-/-. Ces résultats nous indiquent une éventuelle implication de ASC dans la signalisation par le récépteur des cellules T. En parallèle l'expression des différents composants de l'inflammasome a été analysée dans des biopsies de patients atteints de polyarthrite rhumatoide (RA) et d'arthrose (OA). L'expression des 14 différents NALPs, de l'adaptateur ASC, ainsi que des caspase-1 et -5 était similaires dans les échantillons RA et OA, à l'exception de NALP5 et 13 qui n'étaient pas détéctables. L'expression protéique de NALP1, 3, 12 et ASC effectuée par Western blot et immunohistochimie était similaire dans les biopsies RA et OA. Par contre la quantité de la caspase-1 mesurée par ELISA était augmentée de façon significative dans les extraits protéiques de biopsies RA. NALP-1, -2. -3, -10, -12, and -14 ainsi que ASC, caspase-1 et -5 étaient exprimés de façon similaire par les synoviocytes RA non stimulés et stimulés. Dans les synoviocytes seuls ASC et caspase-1 étaient détéctable au niveau protéique. NALP-1, -3 et -12 n'était pas détéctables. Cependant après stimulation il n'y avait d'IL-Ιβ sécrété que ce soit dans les surnageants de cultures de synoviocytes RA ou OA.

Growth and differentiation of aggregating fetal brain cells in a serum-free defined medium.

Aggregating cultures of mechanically dissociated fetal brain cells provide an excellent system for neurobiological studies of cellular growth and differentiation, but, in common with almost all culture systems, they have the disadvantage that crude serum is required in the medium. Although several cell lines have either been adapted to serum-free conditions or grown normally in serum-free media supplemented with hormones, trace elements and defined serum components, this approach has never been applied to differentiating primary cells of the central nervous system. We now describe the successful cultivation of aggregating fetal rat brain cells in a chemically defined, serum-free medium.

Neural regulation of pancreatic islet cell mass and function.

Intracellular glucose signalling pathways control the secretion of glucagon and insulin by pancreatic islet α- and β-cells, respectively. However, glucose also indirectly controls the secretion of these hormones through regulation of the autonomic nervous system that richly innervates this endocrine organ. Both parasympathetic and sympathetic nervous systems also impact endocrine pancreas postnatal development and plasticity in adult animals. Defects in these autonomic regulations impair β-cell mass expansion during the weaning period and β-cell mass adaptation in adult life. Both branches of the autonomic nervous system also regulate glucagon secretion. In type 2 diabetes, impaired glucose-dependent autonomic activity causes the loss of cephalic and first phases of insulin secretion, and impaired suppression of glucagon secretion in the postabsorptive phase; in diabetic patients treated with insulin, it causes a progressive failure of hypoglycaemia to trigger the secretion of glucagon and other counterregulatory hormones. Therefore, identification of the glucose-sensing cells that control the autonomic innervation of the endocrine pancreatic and insulin and glucagon secretion is an important goal of research. This is required for a better understanding of the physiological control of glucose homeostasis and its deregulation in diabetes. This review will discuss recent advances in this field of investigation.

Different PTH response to oral peptone load and oral calcium load in patients with normocalcemic primary hyperparathyroidism, primary hyperparathyroidism, and healthy subjects.

BACKGROUND: Normocalcemic primary hyperparathyroidism (PHPT-N) is a condition that may have similar long-term implications to primary hyperparathyroidism (PHPT); however, differential diagnosis and treatment for parathyroid disorders are not clearly defined. We investigated the effect of an oral peptone and an oral calcium load on calcium-regulating hormones in PHPT-N compared with PHPT and healthy controls to provide a new potential diagnostic tool. DESIGN: Case-control study. METHODS: We evaluated serum gastrin, PTH, ionized calcium, and phosphate responses to oral calcium (1 g) and peptone (10 g) load in 22 PHPT and 20 PHPT-N patients matched for PTH serum values. Moreover, 30 healthy subjects were enrolled as controls. In 12 patients for each group, we also performed the oral peptone test adding aluminum hydroxide (AH) to suppress phosphate absorption. RESULTS: In PHPT patients, PTH increased significantly 30 min after the oral peptone load, while no significant increase was found in PHPT-N and controls. After oral calcium load, PTH remained stable in PHPT while it decreased dramatically in PHPT-N patients, and ionized calcium increased significantly in each of the three groups. Peptones plus AH induced a blunted PTH increase in the three groups. CONCLUSIONS: Considering the marked difference in PTH response elicited by peptones in PHPT compared with PHPT-N, we suggest that the oral peptone test could be added to the diagnostic evaluation of PHPT patients. In case of absent response to peptones, patients should have their serum calcium levels assessed twice a year in accordance with recent guidelines.

AMP-activated protein kinase mediates glucocorticoid-induced metabolic changes: a novel mechanism in Cushing's syndrome.

Chronic exposure to glucocorticoid hormones, resulting from either drug treatment or Cushing's syndrome, results in insulin resistance, central obesity, and symptoms similar to the metabolic syndrome. We hypothesized that the major metabolic effects of corticosteroids are mediated by changes in the key metabolic enzyme adenosine monophosphate-activated protein kinase (AMPK) activity. Activation of AMPK is known to stimulate appetite in the hypothalamus and stimulate catabolic processes in the periphery. We assessed AMPK activity and the expression of several metabolic enzymes in the hypothalamus, liver, adipose tissue, and heart of a rat glucocorticoid-excess model as well as in in vitro studies using primary human adipose and primary rat hypothalamic cell cultures, and a human hepatoma cell line treated with dexamethasone and metformin. Glucocorticoid treatment inhibited AMPK activity in rat adipose tissue and heart, while stimulating it in the liver and hypothalamus. Similar data were observed in vitro in the primary adipose and hypothalamic cells and in the liver cell line. Metformin, a known AMPK regulator, prevented the corticosteroid-induced effects on AMPK in human adipocytes and rat hypothalamic neurons. Our data suggest that glucocorticoid-induced changes in AMPK constitute a novel mechanism that could explain the increase in appetite, the deposition of lipids in visceral adipose and hepatic tissue, as well as the cardiac changes that are all characteristic of glucocorticoid excess. Our data suggest that metformin treatment could be effective in preventing the metabolic complications of chronic glucocorticoid excess.