No description available.

No description available.

No description available.

Systemic sclerosis (Scleroderma, SSc) is a chronic, connective tissue disease of unknown etiology, characterised by vascular dysfunction, iriflarnmation and organ fibrosis. Involving both genetic and environmental components, the specific mechanisms which result in fibrosis remain largely unknown. A cardinal feature of SSc is increased synthesis of extracellular matrix (ECM). Dermal fibroblasts cultured from SSc patients maintain many of the abnormal properties seen in vivo, including excess production of collagen type I, and growth factors such as connective tissue growth factor (CTGF/CCN2). CTGF, like many genes dysregulated in SSc, is induced by TGF- p in normal fibroblasts. The overall aim of my studies was to determine the mechanism(s) controlling CTGF over-expression in SSc dermal fibroblasts (SDF). Induction of CTGF by TGF-p was found to be dependent upon elements in the proximal portion of the CTGF promoter, distinct from those of the previously characterised TGF- P response element (TRE). The TRE acts, in NIH/3T3 and HFF cells, as a regulator of basal expression, and is not essential for TGF-P induction of CTGF. Instead TGF-p induces CTGF expression via a Smad3 complex, binding to a bona fide SMAD transcription factor binding site. Over-expression CTGF in SDF is independent of autocrine expression of TGF-P and the SMAD binding element and rather dependent on a functional Sp-binding site. Inhibition of Spl-like DNA binding reduces excessive CTGF expression in SDF. Consistent with this Spl-DNA binding activity is elevated in SDF nuclear extracts. Investigation of the mechanism of elevated Spl-like binding found that SDF exhibited constitunVely active ERK1/2 and JNK1. Inhibition of ERK1/2 repressed elevated Sp-binding and CTGF over-expression observed in SDF. In summary, the data presented in this thesis provide evidence that dysregulation of ERK1/2 in SDF is involved in CTGF over-expression via a Spl-like DNA binding. Thus repression of ERK may represent a candidate in targeting fibrosis in SSc.

Harlequin ichthyosis (HI), a rare severe form of congenital ichthyosis is caused by recessive mutations in the ABCA12 gene. At birth, affected neonates have widespread, grossly thickened skin, separated by deep red fissures, bilateral ectropion, eclabium and a rudimentary nose and ears. Previously, most babies died shortly after birth but with improved neonatal care and the early introduction of oral retinoids, there is now a cohort of HI survivors. ABCA12 mutation analysis was performed and bi-allelic mutations were identified in 14 out of 17 cases, 9 of which were novel. In one consanguineous case, reverse transcriptase PCR on a parental skin biopsy and copy number analysis were used to identify a multiple exon deletion, when standard techniques failed. A previous study showed that in ABCA12 deficiency, epidermal differentiation is dysregulated. Staining of skin biopsies with RXR-α and PPAR-δ showed that both of these nuclear hormone receptors are up-regulated in the spinous and granular cell layers of HI skin compared to normal skin while ABCA1 is down regulated in the basal layer. The largest review to date of the outcomes of babies born with HI was performed. A retrospective clinical questionnaire was completed for 45 patients worldwide. Survivors’ ages ranged from 10 months to 25 years with an overall survival rate of 55.6%. Death usually occurred in the first 3 months and was attributed to sepsis and/or respiratory failure in 75% if cases. The early introduction of oral retinoids may improve survival as 83% of those treated survived, whereas 76% who were not given retinoids died. Recurrent skin infections in infancy affected one third. Problems maintaining weight affected 44%. Three children developed an inflammatory arthritis and developmental delay was reported in 32%. Mutation analysis revealed that 52% of survivors had compound heterozygous mutations whereas all deaths were associated with homozygous mutations.

La sclérodermie systémique (ScS) est une maladie auto-immune caractérisée par une fibrose cutanée et viscérale ainsi que par des anomalies microcirculatoires. Son origine multifactorielle et ses manifestations cliniques variées en font une maladie à la physiopathologie complexe. Cette maladie rare demeure une affection dont l’étiologie est encore inconnue et pour laquelle il n’existe aucun traitement curatif. Notre laboratoire a mis en évidence le rôle des formes réactives de l’oxygène en mettant au point un modèle animal induit par l’acide hypochloreux. Ce modèle nous a permis d’explorer différentes voies de signalisation intracellulaire, impliquées dans la formation de FRO, favorisant la fibrose. Dans ce travail, nous avons choisi d’explorer dans la sclérodermie systémique différentes voies de signalisation impliquées dans l’inflammation à l’aide d’un modèle de réaction du greffon contre l’hôte sclérodermiforme (GVH-Scl) et d’un modèle de sclérodermie induit par les formes réactives de l’oxygène. De plus, nous avons étudié l’impact de molécules ciblant ces voies afin de fournir de nouvelles données permettent d’enrichir l’arsenal thérapeutique de cette maladie, actuellement pauvre. Les souris obtenues à partir du premier modèle présentent une fibrose cutanée et pulmonaire, une alopécie, une diarrhée et une inflammation hépatique. Une quantité importante d’auto-anticorps ainsi qu’une activation du système immunitaire sont retrouvées. Nous avons observés une activation de la voie de l’EGFR, de STAT3, de Wnt/β-caténine, d’AKT, d’ERK1/2 et de Notch dans la GVH-Scl. L’inhibition de la voie de l’EGFR par l’erlotinib a montré une amélioration clinique associée à une réduction de la fibrose cutanée et de l’inflammation cutanée et hépatique. De plus, l’erlotinib agit sur le système immunitaire et restaure la proportion de LT CD4+ naïfs chez les souris malades ainsi que le taux d’auto-anticorps anti-topoisomérase 1. La co-inhibition des voies de signalisation STAT3, Wnt/β-caténine, AKT, ERK1/2 et Notch par le niclosamide améliore les symptômes de la GVH-Scl chez la souris. Nous avons noté une diminution de la fibrose cutanée et pulmonaire, une diminution de l’inflammation cutanée, hépatique et gastro-intestinale et une diminution de la production d’auto-anticorps. La proportion de cellules naïves parmi les LT CD4+ et CD8+ est plus élevée chez les souris malades traitées que chez les malades non traitées. Les souris du second modèle présentent une fibrose cutanée et pulmonaire et une activation du système immunitaire accompagnée d’une production d’autoanticorps anti-topoisomérase. Nous avons retrouvé une activation des voies de signalisation de STAT3, de Wnt/β-caténine et d’AKT chez les souris sclérodermiques. Nous avons également observés une activation de la voie de signalisation de STAT6 et une surexpression de KLF4 chez ces souris malades. La co-inhibition des voies de signalisation STAT3, Wnt/β-caténine et AKT par le niclosamide améliore la fibrose cutanée et pulmonaire chez les souris sclérodermiques. Cette molécule diminue le nombre et l’activation des LB et des LT CD4+ et CD8+ ainsi que la production des auto-anticorps chez les souris malades. Le traitement de souris sclérodermique par le léflunomide, inhibiteur de STAT6, a aussi montré une amélioration de la fibrose cutanée et pulmonaire et des anomalies immunitaires présentées par les souris sclérodermiques. De plus l’inhibition de STAT6 et de KLF4 par le léflunomide inhibe la polarisation des macrophages en macrophages M2. Ainsi nous avons mis en évidence le rôle des voies de signalisation de l’EGFR, de STAT3, de Wnt/β-caténine, d’AKT, de STAT6 et de KLF4 dans la physiopathologie de la sclérodermie systémique. (...) / Systemic sclerosis (SSc) is a connective tissue disorder that results in skin and inner organs fibrosis, microvascular injuries and auto-immunity. This rare disease has a complex physiopathology which is due to its multifactorial origin and its various clinical manifestations. Its etiology remains unknown and no curative treatment exists at present. Our team highlighted the role of reactive oxygen species (ROS) by developing a hypochlorous acid (HOCl)-induced mouse model of SSc. This model allowed the exploration of several intracellular signalizing pathways which were involved in ROS production and promote fibrosis. In this work, we choose to investigate inflammatory signalizing pathways in SSc with a sclerodermatous graft versus host disease (Scl-GVHD) mouse model and a ROS-induced mouse model. Moreover, we studied the effects of drugs targeting these pathways in order to reinforce data providing new therapeutics. Mice from Scl-GVHD model developed a diffuse cutaneous SSc with pulmonary fibrosis, alopecia, diarrhea and liver inflammation. Production of anti-DNA topoisomerase 1 auto-antibodies and immunological activation was also found. We observed an activation of EGFR, STAT3, Wnt/β-catenin, AKT, ERK1/2 and Notch signaling pathways in Scl-GVHD. Inhibition of EGFR by Erlotinib showed clinical amelioration with a decreased skin fibrosis and decreased skin and liver inflammation. Moreover, Erlotinib decreased production of activated/memory CD4+ T cells and of auto-antibody anti-topoisomerase1. Co-inhibition of STAT3, Wnt/β-catenin, AKT, ERK1/2 and Notch pathways by Niclosamide reversed clinical symptoms of Scl-GVHD in mice. We observed an improvement of skin and lung fibrosis, of cutaneous, hepatic and intestinal inflammation, and a reduced production of auto-antibodies. The ratio of CD4 and CD8 naive T cells was higher in Niclosamide-treated GVHD mice than in untreated GVHD mice. Mice from HOCl-model present skin and lung fibrosis and an immune activation along with the production of auto-antibodies anti-topoisomerase. We found an activation of STAT3, Wnt/β-catenin and AKT signaling pathways in HOCl-mice. We also observed an activation of STAT6 signaling pathway and an overexpression of KLF4 in these sicked mice. Co-inhibition of STAT3, Wnt/β-catenin and AKT pathways by Niclosamide improves skin and lung fibrosis in HOCl-mice. This drug decreased number and activation of B cells and CD4+ and CD8+ T cells and auto-antibodies production in mice. Treatment of HOCl-mice with Leflunomide, STAT6 inhibitor, also showed an improvement of skin and lung fibrosis and of immunological abnormalities in HOCl-mice. Moreover, inhibition of STAT6 and KLF4 by Leflunomide inhibits M2 polarization of macrophages. Thus, we highlighted the role of EGFR, STAT3, Wnt/β-catenin, AKT, STAT6 and KLF4 signaling pathways in physiopathology of SSc. Use of inhibitors of these pathways such as Etrlotinib, Niclosamide and Leflunomide, indicate a clinical and biological efficacity in mouse. These drugs allow the control of the 3 characteristic features of SSc reproduced in these animal models: fibrosis, inflammation and autoimmunity and could thus be effective in fighting the development of clinical-biological abnormalities of SSc.