Rôle des ligands du récepteur au CNTF dans le développement et étude de la signalisation induite par ces cytokines dans des modèles cellulaires de cancer

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal

CC chemokine CCL5 plays a central role impacting infarct size and post-infarction heart failure in mice

Aims The chemokine CCL5 plays a critical role as neutrophil and macrophage activator do in atherosclerosis and myocardial infarction. Thus, we investigated whether the treatment with a neutralizing monoclonal antibody (mAb) to mouse CCL5 would provide therapeutic benefit when provoking a coronary-associated ischaemic event. Methods and Results C57Bl/6 mice were submitted to left coronary artery permanent ligature. Then, various parameters were monitored for up to 21 days. At5 min and 3days after coronary occlusion, mice received one intravenous injection of the rat anti-mouse CCL5 mAb or isotype IgG control. Infarct size was assessed histologically and by measuring serum cardiac troponin I levels. Kinetics of CCL5 tissue expression, leucocyte infiltration, matrix metalloproteinase (MMP) levels, and collagen deposition were histologically assessed. Serum chemokine levels were measured by enzyme-linked immunosorbent assay. Cardiac function and dimensions were assessed by magnetic resonance imaging (MRI). Chronic ischaemia increased both circulating and intracardiac levels of CCL5. At 24 h, treatment with the anti-CCL5 mAb resulted in a smaller infarct size and reduced circulating levels of chemokines. This effect was associated with reduction of neutrophil and macrophage infiltration within the infarcted myocardium. After 3 days of chronic ischaemia, anti-CCL5 mAb treatment reduced cardiac MMP-9. At 7 days, collagen content was significantly lower. At 21 days, neutralizing CCL5 improved mouse survival, cardiac myocyte size, and cardiac function. Conclusion Treatment with anti-CCL5 mAb significantly reduced both infarct size and post-infarction heart failure in a mouse model of chronic cardiac ischaemia. Cardioprotective effects were associated with the reduction of leucocyte recruitment within infarcted heart

Preclinical assessment of a new live attenuated Mycobacterium tuberculosis Beijing-based vaccine for tuberculosis.

Tuberculosis still claims more lives than any other pathogen, and a vaccine better than BCG is urgently needed. One of the challenges for novel TB vaccines is to protect against all Mycobacterium tuberculosis lineages, including the most virulent ones, such as the Beijing lineage. Here we developed a live attenuated M. tuberculosis mutant derived from GC1237, a Beijing strain responsible for tuberculosis outbreaks in the Canary Islands. The mutant strain is inactivated both in the Rv1503c gene, responsible for surface glycolipid synthesis, and in the two-component global regulator PhoPR. This double mutant is as safe as BCG in immunodeficient SCID mice. In immune-competent mice and guinea pigs, the mutant is as protective as BCG against M. tuberculosis strains of common lineage 4 (Euro-American). By contrast, in mice the vaccine is protective against a M. tuberculosis strain of lineage 2 (East-Asian, Beijing), while BCG is not. These results highlight differences in protection efficacy of live attenuated M. tuberculosis-derived vaccine candidates depending on their genetic background, and provide insights for the development of novel live vaccines against TB, especially in East-Asian countries where M. tuberculosis strains of the Beijing family are highly dominant

<em>Mycobacterium leprae</em> PGL1 expression by BCG increases CR3 mediated entry into different myeloid cells

National audienc

<em>Mycobacterium leprae</em> PG-1 production by BCG favors CR3 mediated entry into mouse myeloid cells and incrases SYK-controlled cytokine production

National audienc

<em>Mycobacterium leprae</em> pgl1 expression by BCG increases CR3 mediated entry into mouse myeloid cells and induces Syk/NFAT cytokine production

National audienc

<em>Mycobacterium leprae</em> PGL-1 expression by BCG increases CR3 mediated entry into mouse myeloid cells and triggers the Syk/NFAT pathway to induce a specific cytokine program

National audienceIntroduction : Parmi les molécules lipidiques produites dans la paroi cellulaire des mycobactéries, les glycolipides phénoliques (PGL) ne sont produits que par les principales souches pathogènes pour l’Homme : Mycobacterium tuberculosis (Mtb), M. bovis (Mb) M. leprae et M. ulcerans. Les PGL de ces quatre espèces présentent un squelette lipidique et un noyau phénolique similaires et sont différenciées par leur domaine saccharidique. Grâce à la reprogrammation génétique, nous avons produit des souches de BCG synthétisant le PGL-1 de M. lepra), le PGL-bov (naturellement produit par M. bovis) ainsi qu’une souche déficiente en PGL. Nos travaux précédents ont montré, que la souche rBCG::PGL-1 exploitait le récepteur au complément CR3 pour entrer efficacement dans les macrophages humains et diminuer la réponse inflammatoire (Tabouret et al, 2010). Méthode : Nous avons étudié in vitro et in vivo dans trois types de cellules myéloïdes ; les macrophages (MP), les cellules dendritiques (CD) et neutrophiles (PMN) exprimant toutes les trois fortement le CR3 ; l’impact de PGL-1 – dans le contexte de l’enveloppe naturelle du BCG sur l’entrée de la bactérie et sur la sécrétion de cytokines. Grâce à l’utilisation de différents inhibiteurs, nous avons déterminé les voies de signalisation impliquées. Nous avons utilisé la souris de type sauvage et la souris Itgam-/- déficiente pour le CR3. Résultats : Nous avons observé que rBCG::PGL-1 est capable d’entrer plus efficacement que rBCG::PGL-bov ou rBCG::noPGL dans les MP, les CD et les PMN. Les cellules issues de souris Itgam-/- perdent cette capacité. Le CR3 coopère avec Dectin-1 pour cette entrée plus efficace et la voie Syk est requise. Outre une phagocytose plus efficace, rBCG::PGL-1 induit une forte production d’IL-2 par les CD, d’IL-1b par les MP et d’IL-10 par les PMN en comparaison des deux autres souches. A nouveau, la voie Syk est nécessaire. Au contraire, aucune différence entre les souches n’est observée pour la production de cytokines inflammatoires dépendantes de TLR et MyD88 telles que TNF, IL-6 et IL-12p40. En dessous de la voie Syk, nous montrons également que la voie de signalisation NFAT est engagée efficacement par rBCG::PGL-1 via son entrée efficace par le CR3. Conclusion : Ces résultats montrent que l’expression de PGL-1 confère au BCG la capacité d’exploiter le récepteur CR3 pour envahir les cellules myéloïdes murines dans des conditions non opsonisantes. L’engagement du CR3 active une signalisation impliquant la kinase Syk qui aboutit à l’activation du facteur de transcription NFAT pour engager un programme spécifique de sécrétion de cytokines. La molécule PGL-1 dans le contexte de l’enveloppe mycobactérienne exerce ainsi un effet immunomodulateur important qui pourrait polariser la réponse immunitaire dcifiqu

Sustained treatment‐free remission in chronic myeloid leukaemia is associated with an increased frequency of innate CD8(+) T‐cells

International audienc

Continued Administration of Ciliary Neurotrophic Factor Protects Mice from Inflammatory Pathology in Experimental Autoimmune Encephalomyelitis

Multiple sclerosis is an inflammatory disease of the central nervous system that leads to loss of myelin and oligodendrocytes and damage to axons. We show that daily administration (days 8 to 24) of murine ciliary neurotrophic factor (CNTF), a neurotrophic factor that has been described as a survival and differentiation factor for neurons and oligodendrocytes, significantly ameliorates the clinical course of a mouse model of multiple sclerosis. In the acute phase of experimental autoimmune encephalomyelitis induced by myelin oligodendrocyte glycoprotein peptide 35-55, treatment with CNTF did not change the peripheral immune response but did reduce the number of perivascular infiltrates and T cells and the level of diffuse microglial activation in spinal cord. Blood brain barrier permeability was significantly reduced in CNTF-treated animals. Beneficial effects of CNTF did not persist after it was withdrawn. After cessation of CNTF treatment, inflammation and symptoms returned to control levels. However, slight but significantly higher numbers of oligodendrocytes, NG2-positive cells, axons, and neurons were observed in mice that had been treated with high concentrations of CNTF. Our results show that CNTF inhibits inflammation in the spinal cord, resulting in amelioration of the clinical course of experimental autoimmune encephalomyelitis during time of treatment