Réévaluation de l'impact de l'axe somatotrope GHRH/GH/IGF-1 en immunologie développementale et fonctionnelle

It is now well acknowledged that a close relationship exists between neuroendocrine and immune systems. Within this field, the question of the physiological role of the GHRH/GH/IGF-1 axis on the immune system is still highly debated. The purpose of this thesis was to address this issue by investigating developmental and functional adaptive immunity in the Ghrh-/- mouse model of somatotrope deficiency. Analyses in basal conditions reveal that Ghrh-/- mice have functional B and T lymphopoiesis and exhibit decreased B/T ratio and increased naïve T cells in periphery compared to non-deficient mice, but no immunodeficiency was found. Immune aging was not aggravated in Ghrh-/- mice and short-term GH treatment had no impact on immune parameters of deficient or normal mice, despite its visible metabolic effect. Altogether, those results suggest that somatotrope axis is not required for immune system development, maintenance or aging. This finding is in accordance with the stress hypothesis, according which somatotrope hormones are important counter-regulators of stress-induced immunosuppressors. In an attempt to test this hypothesis, mice were injected with dexamethasone (DXM), a synthetic glucocorticoid inducing massive thymocyte apoptosis. Thymocyte distribution two days post-DXM treatment was less disturbed in Ghrh-/- than in normal mice, but ensuing recovery was slower, even though both mice present full recovery of thymic parameters 10 days after DXM injection. Also in the line of the stress hypothesis, study of infectious stress seems more relevant, as suggested by preliminary results obtained with Streptococcus pneumoniae (S.pneum) infection. In conclusion, this thesis brings new evidence of the non-essential role played by the GHRH/GH/IGF-1 axis on adaptive immune system development and function. It also opens the way for further investigations regarding the role of this axis on innate immunity and immune response to infectious stress./Il est aujourd’hui bien admis qu’une relation étroite existe entre les systèmes neuroendocrinien et immunitaire. Parmi les connaissances dans ce domaine, la question du rôle physiologique exercé par l’axe GHRH/GH/IGF-1 sur le système immunitaire est toujours fortement débattue. L’objectif de cette thèse était d’étudier cette problématique, via l’étude du développement et de la fonction du système immunitaire de la souris Ghrh-/-, un modèle murin de déficience de l’axe somatotrope. A l’état basal, les analyses ont montré que les souris Ghrh-/- avaient une lymphopoïèse B et T fonctionnelle, et présentaient une diminution du rapport B/T et une augmentation des cellules T naïves en périphérie. Cependant, aucune immunodéficience n’a été détectée chez ces souris. Le vieillissement du système immunitaire n’était pas aggravé chez les souris Ghrh-/- et un traitement à court terme par GH s’est révélé sans impact sur les paramètres immunitaires des souris déficientes ou normales. Pris ensemble, ces résultats suggèrent que l’axe somatotrope n’est pas nécessaire pour le développement, la maintenance ou le vieillissement du système immunitaire. Cette conclusion est en accord avec l’hypothèse du stress, selon laquelle les hormones somatotropes seraient d’importants contre-régulateurs des facteurs immunosuppresseurs induits en cas de stress. Pour tester cette hypothèse, les souris ont été injectées avec de la dexaméthasone, un glucocorticoïde de synthèse connu pour induire une atrophie massive des thymocytes. La distribution des thymocytes deux jours après le traitement DXM était moins perturbée chez les souris Ghrh-/- que chez les souris normales, mais la récupération qui s’ensuit semblait retardée, bien que chez les deux types de souris un rétablissement complet des paramètres thymique était obtenu en 10 jours. Egalement en rapport avec l’hypothèse du stress, il semblerait que l’étude du stress infectieux soit mieux adaptée, au vu des résultats préliminaires obtenus avec des infections par Streptococcus Pneumoniae. En conclusion, cette thèse apporte de nouvelles preuves du rôle non essentiel que joue l’axe GHRH/GH/IGF-1 sur le développement et la fonction du système immunitaire et elle ouvre la voie vers de futures études concernant le rôle de l’axe somatotrope sur l’immunité innée et la réponse au stress infectieux

The use of Natural Language Processing as a tool to help exploit hospital data

peer reviewedLe CHU de Liège dispose d’un Dossier Médical Informatisé dans lequel coexistent des données structurées et non structurées. Depuis plus de 10 ans, il a aussi développé un large entrepôt de données clinques compilant l’ensemble de l’information clinique et paraclinique de l’institution. De plus, une équipe d’analystes est devenue experte de l’exploitation des données, essentiellement des données structurées. La question qui se pose actuellement est de savoir comment tirer et exploiter la richesse de toute l’information contenue dans les données non structurées du Dossier Patient Informatisé. Plus particulièrement, les nouvelles technologies de traitement du langage naturel (NLP Natural Langage Processing) apportent-elles une plus-value significative dans l’exploitation des données médicales

Développement d’un outil de pilotage des patients oncologiques au CHU de Liège

peer reviewedLe nombre de cas de cancer est en augmentation constante, en Belgique comme partout dans le monde. Plusieurs services du CHU de Liège se sont regroupés au sein d’un Institut de Cancérologie, afin d’assurer une gestion intégrée multidisciplinaire de cette masse de patients. Cet article présente comment les données de l’entrepôt de données cliniques institutionnel ont été exploitées afin de développer un outil de pilotage transversal de l’activité des patients oncologiques

Investigations on the mechanisms underlying the thymotropic properties of the growth hormone (GH)/insulin-like growth factor 1 (IGF-1) axis.

Background. The thymus is responsible for thymopoiesis, i.e. the generation of a diverse and self-tolerant T-cell repertoire including self-antigen specific natural regulatory cells. We have shown that two parameters of thymopoiesis, thymic output of new T cells (estimated by sjTREC frequency) and intrathymic proliferation of T-cell precursors (estimated by sj/Dβ TREC ratio) are severely reduced in adult patients with GH deficiency (AGHD) and are restored by GH injections at physiological doses. In patients with AGHD, there is a very positive correlation between sjTREC frequency and plasma concentrations of IGF-1, the principal mediator of GH action (1). Treatment of HIV+ patients with high pharmacological doses of GH is associated with increased thymic mass and output of circulating naïve and total CD4+ T cells (2). In addition, previous studies have suggested thymic epithelial cells (TEC) and/or thymocytes (thymic T cells) could transcribe the GH gene (3). Objectives and hypothesis. These studies analysed the question of GH transcription and regulation in primary cultures of human (h) TEC. We also investigated the hypothesis that the thymotropic properties of the somatotrope GH/IGF-1 axis could be mediated by thymic interleukin 7 (IL-7), which plays a crucial role in promoting V(D)J recombination at the TCR locus. Results. Primary hTEC cultures were treated with natural secretagogues of pituitary GH, GH releasing hormone (GHRH) and ghrelin. Using sensitive RT-qPCR, we detected neither any transcript of GH or GHV (placental GH variant) in cultured hTEC, nor any transcript of PIT1, the specific transcription factor of pituitary GH. Similarly, the protein GH was detected neither in the cytoplasm nor in the supernatant of cultured hTEC. Only at 1 nM, GH treatment enhanced IGF1 transcription by cultured hTEC. Of high interest, treatment with GH, ghrelin and IGF-1 promoted IL7 transcription by cultured hTEC, but only IGF-1 and epidermal growth factor (EGF) markedly stimulated IL-7 secretion by hTEC in a dose- and time-dependent manner. The specificity of IGF-1 action was demonstrated by its inhibition after treatment with αIR3, a monoclonal antibody against the type 1 IGF receptor. Conclusions and perspectives. Since primary cultures of hTEC neither transcribe nor secrete any significant amount of GH, the thymotropic effects of the GH/IGF-1 axis seem to depend only on systemic endocrine GH. Local thymic IGF-1 could partially mediate GH action within the thymus and act upon thymopoiesis in parallel with systemic IGF-1. Most importantly, thymic IL-7 appears to be an important mediator of the thymotropic properties of the GH/IGF-1 axis. Further knowledge in this domain will be gained with the use and supplementation of Ghrh-/- mice that will be soon available in our laboratory. References 1. Morrhaye G. et al., PLoS ONE 2009, 4:e5668. 2. Napolitano LA et al. J Clin Invest 2008, 118:1085. 3. Smaniotto S et al., Endocrinology 2005, 146:3005. 4. Taub DD, Murphy WJ and Longo DL. Curr Opin Pharmacol 2010, 10:408. (Supported by F.R.S.-FNRS and a Pfizer Independent Research Grant.

Growth hormone (GH) deficient mice with GHRH ablation are severely deficient in vaccine and immune responses against Streptococcus pneumoniae

SOMASTHY

A surprising and dramatic neuroendocrine-immune phenotype of mice deficient in Growth Hormone-Releasing Hormone (GHRH)

In the framework of close interactions between the immune and neuroendocrine systems, Growth Hormone (GH) has been proposed to exert significant effects on the immune system, but there is not yet a consensus about GH immunomodulatory properties. These studies investigated the immune and anti-infectious response of dwarf Ghrh-/- mice presenting a severe deficiency of the GHRH/GH/IGF-1 axis. In basal conditions, thymic parameters and T-cell responses of Ghrh-/- mice were not severely affected but a constant B-cell lymphopaenia was observed. Thus, we investigated vaccine and anti-infectious responses of Ghrh-/- mice toward Streptococcus pneumonia, a B-dependent pathogen, Ghrh-/- mice were unable to trigger production of specific IgM and IgG against serotype 1 pneumococcal polysaccharide (PPS) after vaccination with either native PPS (Pnx23) or protein-PPS conjugate (Prev-13) vaccines. These vaccines both include the serotype 1 (our S.pneumoniae strain) and provide an effective protection in mice. A short GH supplementation to Ghrh-/- mice (1 daily injection of 1 mg/kg GH for 4 weeks) restored IgM and IgG response to Pnx23 vaccine but not to Prev-13. This suggests that GH could exert distinct impacts upon spenic areas. Furthermore, after intranasal instillation of a non-lethal dose (defined by the full clearance by WT C57BL/6 mice after 24h) of serotype 1 S.pneumoniae, Ghrh-/- mice exhibited a dramatic susceptibility. This was proved by a marked time-dependent increase in pulmonary bacterial, a septicemia already 24h after infection and a survival limit of 72h. We also observed a dramatic decrease in lung B- and T-cell populations and an increase in proportion of inflammatory macrophages. By contrast, wild-type and heterozygote mice completely cleared S.pneumoniae infection after 24h. In conclusion, our data show without ambiguity that the somatotrope GHRH/GH/IGF-1 axis plays an important and unsuspected role in defense against S.Pneumoniae.ARC SOMASTHY

Severe deficiency of the somatotrope GHRH/GH/IGF-1 axis induces a dramatic susceptibility to Streptococcus pneumoniae infection.

Deletion of the growth hormone-releasing hormone gene (Ghrh) results in a severe deficiency of the somatotrope GHRH-GH-IGF-1 axis causing dwarf phenotype that can be reversed by GH or GHRH supplementation (Alba & Salvatori, Endocrinology 2004;145:4134). In basal conditions, the immunological phenotype of Ghrh-/- mice is not markedly disturbed except for a decrease in B cells and an increase in generation of thymic (t) Treg cells (submitted for publication). These data prompted us to investigate immune responses of Ghrh-/- mice using vaccination and infection by S. pneumoniae as models since the response to both stimuli rely on the innate immune system and B cells. Ghrh-/- mice were unable to trigger production of specific IgM and IgG against serotype 1 pneumococcal polysaccharide (PPS) after vaccination with either native PPS (Pnx23) or protein-PPS conjugate (Prev-13) vaccines. A short GH supplementation to Ghrh-/- mice (1 daily injection of 1 mg/kg GH for 4 weeks) restored IgM and IgG response to Pnx23 vaccine but not to Prev-13. This suggests that GH differently impacts on B-1, marginal zone B-2 or innate B-1 B cells. Furthermore, after intranasal instillation of a non-lethal dose of serotype 1 S. pneumoniae, Ghrh-/- mice exhibited a dramatic susceptibility reflected by bacteremia 24h after infection and a survival limit of 72 h, compared to WT C57BL/6 mice that need only 24h to clear infection. The possible impact of GH deficiency on components of the innate immune system that play an important role in defense of the respiratory tract against pneumococcal infection is under current investigation. (*Equal first and last authors. KF is supported by a research grant from the Lebanese Government; GB is Research Assistant, CD is Research Associate, and VG is Research Director at the NFSR of Belgium).SOMASTHYM - The somatotrope GHRH/GH/IGF1 axis and immune reconstitution through thymus recovery

The somatotrope Growth Hormone-Releasing Hormone/Growth Hormone/Insulin-like Growth Factor 1 axis in immunoregulation and immunosenescence

peer reviewedMost scientific reports debate the thymotropic and immuno-stimulating properties of the somato- trope growth hormone-releasing hormone (GHRH)/growth hormone (GH)/insulin-like growth factor (IGF)-1 axis, but there is still some disagreement about the physiological role of this axis in basal conditions. Moreover, some authors have hypothesized that the physiological role of the somato- trope axis only appears in stressful conditions (such as sepsis or infective and inflammatory diseases). This chapter will provide an extended overview of the expression of the components (signals and receptors) of the somatotrope axis and their properties on cells of the innate and adaptive immune system. It will also summarize some clinical studies suggesting a benefit for a short-term GH treat- ment in acute immunodeficiencies, and the importance of GH supplementation in adult GH defi- ciency. A new transgenic mouse model, the hypothalamic GHRH-deficient (Ghrh–/–) mouse, which exhibits a severe deficiency of the somatotrope axis, will be presented since it will be of great help in further deciphering the regulation by the GHRH/GH/IGF-1 axis on both immune development and function. Finally, we will discuss the implication of aging-related somatopause in relation to the general context of Immunosenescence