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International audience; Since their efficiency to treat graft versus host disease has been proven, mesenchymal stem cells (MSC) represent a promising cell therapy approach for the treatment of immune disorders. In this context, much attention has focused on their mechanisms of action, in particular once the fact that their immune properties are also crucial for their efficiency in regenerative medicine was demonstrated. By their production of various and redundant soluble factors, MSC exert powerful anti-inflammatory and immunosuppressive effects targeting the main immune cell subsets. These immunoregulatory properties are essentially inducible by inflammatory mediators. In addition, it is now clear that allogeneic MSC are not immunoprivileged in immunocompetent recipient in agreement with their low persistence in vivo. They should thus display an early "touch-and-go" effect involving both direct interactions with recruited immune effectors and further amplification of this immunosuppression process through activation or conditioning of other regulatory immune cells. A better understanding of immunological properties of MSC will clearly improve their use in clinical settings.; Les cellules souches mésenchymateuses (CSM) possèdent des propriétés immunosuppressives très vastes liées à la production de facteurs solubles inductibles qui inhibent l'activation des principaux effecteurs de l'immunité. L'intérêt de ces propriétés a été confirmé dans des essais cliniques spectaculaires chez des patients atteints de la maladie du greffon contre l'hôte, une complication fréquente et grave des allogreffes de cellules souches hématopoïétiques. Depuis, les applications de ce potentiel anti-inflammatoire et immunosuppresseur des CSM ont été étendues à la médecine régénératrice puisque les capacités de réparation des CSM semblent étroitement liées à leurs propriétés immunologiques, démontrant tout l'intérêt d'une compréhension fine des interactions entre les CSM et les cellules immunitaires.

International audience; Rabies is a fatal disease transmitted by infected animals by bite, scratch, licking on broken skin or contamination of mucosis by saliva. The regimen of post-exposure prophylaxis for people not previously vaccinated, that is currently recommended by WHO, consists of a combination of wound cleaning, active immunization and passive immunization when the exposure is of category 3. Most of the products available on the market, in particular human rabies immunoglobulins, highly purified equine rabies immunoglobulins and the derived F(ab')(2) fragments, are now characterized by high potency and safety. Although the interest of passive anti-rabies immunization was first demonstrated in the first half of the 20th century, there is still an inadequate supply of these products to the target populations mostly in developing countries. Therefore, it is urgent to set-up training and information actions for healthcare personnel on the need to use passive immunotherapy and the lack of adverse effects of the related products. For the future, we hope that a scale up of production and a lower price will improve the accessibility to these products. The development of new products based on monoclonal antibodies and molecular biology, and which may be cheaper, is promising.

International audience; INTRODUCTION: Children living in rural areas had lower prevalence of allergies than children from cities, in relation to farming exposure. STATE OF ART: Exposure to farm animals and consumption of raw milk appear to play an important role in the protection afforded by the agricultural environment, and this at different stages of child development. The mechanisms involved in these effects are still controversial, and recent publications cast doubt on the role of endotoxins initially suggested. It seems that exposure to indoor air pollution, characterized by excessive biocontaminants (mold, allergens...) is a key element in the development of allergic diseases. PERSPECTIVES: The establishment of cohort studies, a better assessment of exposure to pollution at home but also in farm buildings and the study of gene-environment interactions should improve the knowledge on the protective effect towards allergy of farming environment. CONCLUSIONS: The farming environment, very specific, could be an important model for better understanding the mechanisms involved in allergic and respiratory diseases. In addition, urbanization and thus reduction of the rural environment, may well explain the increased prevalence of allergies observed in the past 50 years.

International audience; Rabies is a fatal disease transmitted by infected animals by bite, scratch, licking on broken skin or contamination of mucosis by saliva. The regimen of post-exposure prophylaxis for people not previously vaccinated, that is currently recommended by WHO, consists of a combination of wound cleaning, active immunization and passive immunization when the exposure is of category 3. Most of the products available on the market, in particular human rabies immunoglobulins, highly purified equine rabies immunoglobulins and the derived F(ab')(2) fragments, are now characterized by high potency and safety. Although the interest of passive anti-rabies immunization was first demonstrated in the first half of the 20th century, there is still an inadequate supply of these products to the target populations mostly in developing countries. Therefore, it is urgent to set-up training and information actions for healthcare personnel on the need to use passive immunotherapy and the lack of adverse effects of the related products. For the future, we hope that a scale up of production and a lower price will improve the accessibility to these products. The development of new products based on monoclonal antibodies and molecular biology, and which may be cheaper, is promising.

International audience

International audience; Hepatitis C virus (HCV) becomes chronic in about 85 % of infected individuals, whereas only 15 % of infected people clear spontaneously the virus. The progression of hepatitis C to chronic status is associated to a profound down-regulation of CD4 and CD8 multispecific immune response. This immune defect may participate to the immune tolerance of VHC and consequently to its persistence. Recent findings indicate that T regulatory cells as Tr1 play an inhibitory role on T helper responses notably in the context of auto-immune or inflammatory disorders. The existence of immunosuppressive mechanisms supported by Tr1 lymphocytes and their IL-10 production represent an attractive hypothesis. We have previously evaluated the existence of regulatory T cells (Tr1) via high production of IL-10, in liver biopsies of three well-defined cohorts of HCV-1b infected patients. To this purpose, we compared liver biopsies of chronically infected patients including patients without liver lesions, with cirrhosis and with hepatocellular carcinoma (HCC). Using quantitative real time PCR, the results obtained demonstrate, an increased expression of interleukin-10 (IL-10) and transforming growth factor-beta (TGF-beta)_, in liver biopsies with more severe fibrosis. This observation was correlated with an increased expression during the pathogenesis progression, of the three specific markers of the Tr1 cells sub-population, recently described and confirming the Tr1 phenotype. Evidence of regulatory T cells installation in the liver of chronically infected patient and increased frequency in cirrhosis and HCC suggest a main role of these cells in the aggravation of the liver pathology. This study should bring insight of T regulatory cell implications in VHC persistence and in the pathology progression.