Overblog Suivre ce blog
Administration Créer mon blog
10 juillet 2013 3 10 /07 /juillet /2013 06:50
Breck A Duerkop & Lora V Hooper AffiliationsCorresponding author Nature Immunology 14, 654–659 (2013) doi:10.1038/ni.2614 Received 18 February 2013 Accepted 16 April 2013 Published online 18 June 2013 The human body is colonized with a diverse resident microflora that includes viruses. Recent studies of metagenomes have begun to characterize the composition of the human 'virobiota' and its associated genes (the 'virome'), and have fostered the emerging field of host-virobiota interactions. In this Perspective, we explore how resident viruses interact with the immune system. We review recent findings that highlight the role of the immune system in shaping the composition of the virobiota and consider how resident viruses may impact host immunity. Finally, we discuss the implications of virobiota–immune system interactions for human health. Hooper, L.V., Littman, D.R. & Macpherson, A.J. Interactions between the microbiota and the immune system. Science 336, 1268–1273 (2012). CASADSPubMedArticle Lozupone, C.A., Stombaugh, J.I., Gordon, J.I., Jansson, J.K. & Knight, R. Diversity, stability and resilience of the human gut microbiota. Nature 489, 220–230 (2012). CASADSPubMedArticle White, D.W., Suzanne Beard, R. & Barton, E.S. Immune modulation during latent herpesvirus infection. Immunol. Rev. 245, 189–208 (2012). CASPubMedArticle Handley, S.A. et al. Pathogenic simian immunodeficiency virus infection is associated with expansion of the enteric virome. Cell 151, 253–266 (2012). CASPubMedArticle Reyes, A. et al. Viruses in the faecal microbiota of monozygotic twins and their mothers. Nature 466, 334–338 (2010). CASADSISIPubMedArticle Minot, S. et al. The human gut virome: inter-individual variation and dynamic response to diet. Genome Res. 21, 1616–1625 (2011). CASADSPubMedArticle Foulongne, V. et al. Human skin microbiota: high diversity of DNA viruses identified on the human skin by high throughput sequencing. PLoS ONE 7, e38499 (2012). CASADSPubMedArticle Zhang, T. et al. RNA viral community in human feces: prevalence of plant pathogenic viruses. PLoS Biol. 4, e3 (2006). CASPubMedArticle Turnbaugh, P.J. et al. A core gut microbiome in obese and lean twins. Nature 457, 480–484 (2009). CASADSISIPubMedArticle Pride, D.T. et al. Evidence of a robust resident bacteriophage population revealed through analysis of the human salivary virome. ISME J. 6, 915–926 (2012). CASPubMedArticle Breitbart, M. et al. Viral diversity and dynamics in an infant gut. Res. Microbiol. 159, 367–373 (2008). CASISIPubMedArticle Weinbauer, M.G. Ecology of prokaryotic viruses. FEMS Microbiol. Rev. 28, 127–181 (2004). CASISIPubMedArticle DeMarini, D.M. & Lawrence, B.K. Prophage induction by DNA topoisomerase II poisons and reactive-oxygen species: role of DNA breaks. Mutat. Res. 267, 1–17 (1992). CASPubMedArticle Duerkop, B.A., Clements, C.V., Rollins, D., Rodrigues, J.L. & Hooper, L.V. A composite bacteriophage alters colonization by an intestinal commensal bacterium. Proc. Natl. Acad. Sci. USA 109, 17621–17626 (2012). ADSPubMedArticle Kim, M.S., Park, E.J., Roh, S.W. & Bae, J.W. Diversity and abundance of single-stranded DNA viruses in human feces. Appl. Environ. Microbiol. 77, 8062–8070 (2011). CASPubMedArticle Canchaya, C., Fournous, G., Chibani-Chennoufi, S., Dillmann, M.L. & Brussow, H. Phage as agents of lateral gene transfer. Curr. Opin. Microbiol. 6, 417–424 (2003). CASISIPubMedArticle Pride, D.T., Salzman, J. & Relman, D.A. Comparisons of clustered regularly interspaced short palindromic repeats and viromes in human saliva reveal bacterial adaptations to salivary viruses. Environ. Microbiol. 14, 2564–2576 (2012). CASPubMedArticle Ivanov, I.I. et al. Specific microbiota direct the differentiation of IL-17-producing T-helper cells in the mucosa of the small intestine. Cell Host Microbe 4, 337–349 (2008). CASISIPubMedArticle Mazmanian, S.K., Liu, C.H., Tzianabos, A.O. & Kasper, D.L. An immunomodulatory molecule of symbiotic bacteria directs maturation of the host immune system. Cell 122, 107–118 (2005). CASISIPubMedArticle Kuss, S.K. et al. Intestinal microbiota promote enteric virus replication and systemic pathogenesis. Science 334, 249–252 (2011). CASADSPubMedArticle Ichinohe, T. et al. Microbiota regulates immune defense against respiratory tract influenza A virus infection. Proc. Natl. Acad. Sci. USA 108, 5354–5359 (2011). ADSPubMedArticle Kane, M. et al. Successful transmission of a retrovirus depends on the commensal microbiota. Science 334, 245–249 (2011). CASADSPubMedArticle Schowalter, R.M., Pastrana, D.V., Pumphrey, K.A., Moyer, A.L. & Buck, C.B. Merkel cell polyomavirus and two previously unknown polyomaviruses are chronically shed from human skin. Cell Host Microbe 7, 509–515 (2010). CASISIPubMedArticle Miller, C.S., Avdiushko, S.A., Kryscio, R.J., Danaher, R.J. & Jacob, R.J. Effect of prophylactic valacyclovir on the presence of human herpesvirus DNA in saliva of healthy individuals after dental treatment. J. Clin. Microbiol. 43, 2173–2180 (2005). CASPubMedArticle Lazarevic, V. et al. Analysis of the salivary microbiome using culture-independent techniques. J. Clin. Bioinforma. 2, 4 (2012). CASPubMedArticle Bogaert, D. et al. Variability and diversity of nasopharyngeal microbiota in children: a metagenomic analysis. PLoS ONE 6, e17035 (2011). CASADSPubMedArticle Nokso-Koivisto, J., Kinnari, T.J., Lindahl, P., Hovi, T. & Pitkaranta, A. Human picornavirus and coronavirus RNA in nasopharynx of children without concurrent respiratory symptoms. J. Med. Virol. 66, 417–420 (2002). PubMedArticle Minot, S., Grunberg, S., Wu, G.D., Lewis, J.D. & Bushman, F.D. Hypervariable loci in the human gut virome. Proc. Natl. Acad. Sci. USA 109, 3962–3966 (2012). CASADSPubMedArticle Victoria, J.G. et al. Metagenomic analyses of viruses in stool samples from children with acute flaccid paralysis. J. Virol. 83, 4642–4651 (2009). CASPubMedArticle Finkbeiner, S.R. et al. Metagenomic analysis of human diarrhea: viral detection and discovery. PLoS Pathog. 4, e1000011 (2008). CASPubMedArticle Lee, Y.K. & Mazmanian, S.K. Has the microbiota played a critical role in the evolution of the adaptive immune system? Science 330, 1768–1773 (2010). CASADSISIPubMedArticle McFall-Ngai, M. Adaptive immunity: care for the community. Nature 445, 153 (2007). CASADSISIPubMedArticle Vaishnava, S. et al. The antibacterial lectin RegIIIγ promotes the spatial segregation of microbiota and host in the intestine. Science 334, 255–258 (2011). CASADSPubMedArticle Salzman, N.H. et al. Enteric defensins are essential regulators of intestinal microbial ecology. Nat. Immunol. 11, 76–83 (2010). CASISIPubMedArticle Lysholm, F. et al. Characterization of the viral microbiome in patients with severe lower respiratory tract infections, using metagenomic sequencing. PLoS ONE 7, e30875 (2012). CASADSPubMedArticle Willner, D. et al. Metagenomic analysis of respiratory tract DNA viral communities in cystic fibrosis and non-cystic fibrosis individuals. PLoS ONE 4, e7370 (2009). CASADSPubMedArticle Brandl, K. et al. Vancomycin-resistant enterococci exploit antibiotic-induced innate immune deficits. Nature 455, 804–807 (2008). CASADSISIPubMedArticle Fukuda, S. et al. Bifidobacteria can protect from enteropathogenic infection through production of acetate. Nature 469, 543–547 (2011). CASADSISIPubMedArticle Virgin, H.W., Wherry, E.J. & Ahmed, R. Redefining chronic viral infection. Cell 138, 30–50 (2009). CASISIPubMedArticle Barton, E.S. et al. Herpesvirus latency confers symbiotic protection from bacterial infection. Nature 447, 326–329 (2007). CASADSISIPubMedArticle Zuniga, E.I., Liou, L.Y., Mack, L., Mendoza, M. & Oldstone, M.B. Persistent virus infection inhibits type I interferon production by plasmacytoid dendritic cells to facilitate opportunistic infections. Cell Host Microbe 4, 374–386 (2008). CASISIPubMedArticle Inchley, C.J. & Howard, J.G. The immunogenicity of phagocytosed T4 bacteriophage: cell replacement studies with splenectomized and irradiated mice. Clin. Exp. Immunol. 5, 189–198 (1969). CASPubMed Nelson, J., Ormrod, D.J., Wilson, D. & Miller, T.E. Host immune status in uraemia III. Humoral response to selected antigens in the rat. Clin. Exp. Immunol. 42, 234–240 (1980). CASPubMed Gorski, A. et al. Bacteriophages and transplantation tolerance. Transplant. Proc. 38, 331–333 (2006). CASPubMedArticle Eriksson, F. et al. Tumor-specific bacteriophages induce tumor destruction through activation of tumor-associated macrophages. J. Immunol. 182, 3105–3111 (2009). CASPubMedArticle Mori, K., Kubo, T., Kibayashi, Y., Ohkuma, T. & Kaji, A. Anti-vaccinia virus effect of M13 bacteriophage DNA. Antiviral Res. 31, 79–86 (1996). CASPubMedArticle Abstract• References• Author information Hooper, L.V., Littman, D.R. & Macpherson, A.J. Interactions between the microbiota and the immune system. Science 336, 1268–1273 (2012). CASADSPubMedArticle Lozupone, C.A., Stombaugh, J.I., Gordon, J.I., Jansson, J.K. & Knight, R. Diversity, stability and resilience of the human gut microbiota. Nature 489, 220–230 (2012). CASADSPubMedArticle White, D.W., Suzanne Beard, R. & Barton, E.S. Immune modulation during latent herpesvirus infection. Immunol. Rev. 245, 189–208 (2012). CASPubMedArticle Handley, S.A. et al. Pathogenic simian immunodeficiency virus infection is associated with expansion of the enteric virome. Cell 151, 253–266 (2012). CASPubMedArticle Reyes, A. et al. Viruses in the faecal microbiota of monozygotic twins and their mothers. Nature 466, 334–338 (2010). CASADSISIPubMedArticle Minot, S. et al. The human gut virome: inter-individual variation and dynamic response to diet. Genome Res. 21, 1616–1625 (2011). CASADSPubMedArticle Foulongne, V. et al. Human skin microbiota: high diversity of DNA viruses identified on the human skin by high throughput sequencing. PLoS ONE 7, e38499 (2012). CASADSPubMedArticle Zhang, T. et al. RNA viral community in human feces: prevalence of plant pathogenic viruses. PLoS Biol. 4, e3 (2006). CASPubMedArticle Turnbaugh, P.J. et al. A core gut microbiome in obese and lean twins. Nature 457, 480–484 (2009). CASADSISIPubMedArticle Pride, D.T. et al. Evidence of a robust resident bacteriophage population revealed through analysis of the human salivary virome. ISME J. 6, 915–926 (2012). CASPubMedArticle Breitbart, M. et al. Viral diversity and dynamics in an infant gut. Res. Microbiol. 159, 367–373 (2008). CASISIPubMedArticle Weinbauer, M.G. Ecology of prokaryotic viruses. FEMS Microbiol. Rev. 28, 127–181 (2004). CASISIPubMedArticle DeMarini, D.M. & Lawrence, B.K. Prophage induction by DNA topoisomerase II poisons and reactive-oxygen species: role of DNA breaks. Mutat. Res. 267, 1–17 (1992). CASPubMedArticle Duerkop, B.A., Clements, C.V., Rollins, D., Rodrigues, J.L. & Hooper, L.V. A composite bacteriophage alters colonization by an intestinal commensal bacterium. Proc. Natl. Acad. Sci. USA 109, 17621–17626 (2012). ADSPubMedArticle Kim, M.S., Park, E.J., Roh, S.W. & Bae, J.W. Diversity and abundance of single-stranded DNA viruses in human feces. Appl. Environ. Microbiol. 77, 8062–8070 (2011). CASPubMedArticle Canchaya, C., Fournous, G., Chibani-Chennoufi, S., Dillmann, M.L. & Brussow, H. Phage as agents of lateral gene transfer. Curr. Opin. Microbiol. 6, 417–424 (2003). CASISIPubMedArticle Pride, D.T., Salzman, J. & Relman, D.A. Comparisons of clustered regularly interspaced short palindromic repeats and viromes in human saliva reveal bacterial adaptations to salivary viruses. Environ. Microbiol. 14, 2564–2576 (2012). CASPubMedArticle Ivanov, I.I. et al. Specific microbiota direct the differentiation of IL-17-producing T-helper cells in the mucosa of the small intestine. Cell Host Microbe 4, 337–349 (2008). CASISIPubMedArticle Mazmanian, S.K., Liu, C.H., Tzianabos, A.O. & Kasper, D.L. An immunomodulatory molecule of symbiotic bacteria directs maturation of the host immune system. Cell 122, 107–118 (2005). CASISIPubMedArticle Kuss, S.K. et al. Intestinal microbiota promote enteric virus replication and systemic pathogenesis. Science 334, 249–252 (2011). CASADSPubMedArticle Ichinohe, T. et al. Microbiota regulates immune defense against respiratory tract influenza A virus infection. Proc. Natl. Acad. Sci. USA 108, 5354–5359 (2011). ADSPubMedArticle Kane, M. et al. Successful transmission of a retrovirus depends on the commensal microbiota. Science 334, 245–249 (2011). CASADSPubMedArticle Schowalter, R.M., Pastrana, D.V., Pumphrey, K.A., Moyer, A.L. & Buck, C.B. Merkel cell polyomavirus and two previously unknown polyomaviruses are chronically shed from human skin. Cell Host Microbe 7, 509–515 (2010). CASISIPubMedArticle Miller, C.S., Avdiushko, S.A., Kryscio, R.J., Danaher, R.J. & Jacob, R.J. Effect of prophylactic valacyclovir on the presence of human herpesvirus DNA in saliva of healthy individuals after dental treatment. J. Clin. Microbiol. 43, 2173–2180 (2005). CASPubMedArticle Lazarevic, V. et al. Analysis of the salivary microbiome using culture-independent techniques. J. Clin. Bioinforma. 2, 4 (2012). CASPubMedArticle Bogaert, D. et al. Variability and diversity of nasopharyngeal microbiota in children: a metagenomic analysis. PLoS ONE 6, e17035 (2011). CASADSPubMedArticle Nokso-Koivisto, J., Kinnari, T.J., Lindahl, P., Hovi, T. & Pitkaranta, A. Human picornavirus and coronavirus RNA in nasopharynx of children without concurrent respiratory symptoms. J. Med. Virol. 66, 417–420 (2002). PubMedArticle Minot, S., Grunberg, S., Wu, G.D., Lewis, J.D. & Bushman, F.D. Hypervariable loci in the human gut virome. Proc. Natl. Acad. Sci. USA 109, 3962–3966 (2012). CASADSPubMedArticle Victoria, J.G. et al. Metagenomic analyses of viruses in stool samples from children with acute flaccid paralysis. J. Virol. 83, 4642–4651 (2009). CASPubMedArticle Finkbeiner, S.R. et al. Metagenomic analysis of human diarrhea: viral detection and discovery. PLoS Pathog. 4, e1000011 (2008). CASPubMedArticle Lee, Y.K. & Mazmanian, S.K. Has the microbiota played a critical role in the evolution of the adaptive immune system? Science 330, 1768–1773 (2010). CASADSISIPubMedArticle McFall-Ngai, M. Adaptive immunity: care for the community. Nature 445, 153 (2007). CASADSISIPubMedArticle Vaishnava, S. et al. The antibacterial lectin RegIIIγ promotes the spatial segregation of microbiota and host in the intestine. Science 334, 255–258 (2011). CASADSPubMedArticle Salzman, N.H. et al. Enteric defensins are essential regulators of intestinal microbial ecology. Nat. Immunol. 11, 76–83 (2010). CASISIPubMedArticle Lysholm, F. et al. Characterization of the viral microbiome in patients with severe lower respiratory tract infections, using metagenomic sequencing. PLoS ONE 7, e30875 (2012). CASADSPubMedArticle Willner, D. et al. Metagenomic analysis of respiratory tract DNA viral communities in cystic fibrosis and non-cystic fibrosis individuals. PLoS ONE 4, e7370 (2009). CASADSPubMedArticle Brandl, K. et al. Vancomycin-resistant enterococci exploit antibiotic-induced innate immune deficits. Nature 455, 804–807 (2008). CASADSISIPubMedArticle Fukuda, S. et al. Bifidobacteria can protect from enteropathogenic infection through production of acetate. Nature 469, 543–547 (2011). CASADSISIPubMedArticle Virgin, H.W., Wherry, E.J. & Ahmed, R. Redefining chronic viral infection. Cell 138, 30–50 (2009). CASISIPubMedArticle Barton, E.S. et al. Herpesvirus latency confers symbiotic protection from bacterial infection. Nature 447, 326–329 (2007). CASADSISIPubMedArticle Zuniga, E.I., Liou, L.Y., Mack, L., Mendoza, M. & Oldstone, M.B. Persistent virus infection inhibits type I interferon production by plasmacytoid dendritic cells to facilitate opportunistic infections. Cell Host Microbe 4, 374–386 (2008). CASISIPubMedArticle Inchley, C.J. & Howard, J.G. The immunogenicity of phagocytosed T4 bacteriophage: cell replacement studies with splenectomized and irradiated mice. Clin. Exp. Immunol. 5, 189–198 (1969). CASPubMed Nelson, J., Ormrod, D.J., Wilson, D. & Miller, T.E. Host immune status in uraemia III. Humoral response to selected antigens in the rat. Clin. Exp. Immunol. 42, 234–240 (1980). CASPubMed Gorski, A. et al. Bacteriophages and transplantation tolerance. Transplant. Proc. 38, 331–333 (2006). CASPubMedArticle Eriksson, F. et al. Tumor-specific bacteriophages induce tumor destruction through activation of tumor-associated macrophages. J. Immunol. 182, 3105–3111 (2009). CASPubMedArticle Mori, K., Kubo, T., Kibayashi, Y., Ohkuma, T. & Kaji, A. Anti-vaccinia virus effect of M13 bacteriophage DNA. Antiviral Res. 31, 79–86 (1996). CASPubMedArticle Duerr, D.M., White, S.J. & Schluesener, H.J. Identification of peptide sequences that induce the transport of phage across the gastrointestinal mucosal barrier. J. Virol. Methods 116, 177–180 (2004). CASISIPubMedArticle Hamzeh-Mivehroud, M., Mahmoudpour, A., Rezazadeh, H. & Dastmalchi, S. Non-specific translocation of peptide-displaying bacteriophage particles across the gastrointestinal barrier. Eur. J. Pharm. Biopharm. 70, 577–581 (2008). CASPubMedArticle Keller, R. & Engley, F.B. Jr. Fate of bacteriophage particles introduced into mice by various routes. Proc. Soc. Exp. Biol. Med. 98, 577–580 (1958). CASPubMed Rescigno, M. et al. Dendritic cells express tight junction proteins and penetrate gut epithelial monolayers to sample bacteria. Nat. Immunol. 2, 361–367 (2001). CASISIPubMedArticle Barfoot, R. et al. Some properties of dendritic macrophages from peripheral lymph. Immunology 68, 233–239 (1989). CASPubMed Gorski, A. et al. Bacteriophage translocation. FEMS Immunol. Med. Microbiol. 46, 313–319 (2006). CASPubMedArticle Lepage, P. et al. Dysbiosis in inflammatory bowel disease: a role for bacteriophages? Gut 57, 424–425 (2008). CASPubMedArticle Yan, N. & Chen, Z.J. Intrinsic antiviral immunity. Nat. Immunol. 13, 214–222 (2012). CASPubMedArticle Sun, L., Wu, J., Du, F., Chen, X. & Chen, Z.J. Cyclic GMP-AMP synthase is a cytosolic DNA sensor that activates the type I interferon pathway. Science 339, 786–791 (2013). CASADSPubMedArticle Wu, J. et al. Cyclic GMP-AMP is an endogenous second messenger in innate immune signaling by cytosolic DNA. Science 339, 826–830 (2013). CASADSPubMedArticle Doulatov, S. et al. Tropism switching in Bordetella bacteriophage defines a family of diversity-generating retroelements. Nature 431, 476–481 (2004). CASADSISIPubMedArticle
Repost 0
Published by Chronimed - dans Infections froides
commenter cet article
10 juillet 2013 3 10 /07 /juillet /2013 06:44
Yasmine Belkaid & Shruti Naik AffiliationsCorresponding author Nature Immunology 14, 646–653 (2013) doi:10.1038/ni.2604 Received 05 February 2013 Accepted 02 April 2013 Published online 18 June 2013 The body is composed of various tissue microenvironments with finely tuned local immunosurveillance systems, many of which are in close apposition with distinct commensal niches. Mammals have formed an evolutionary partnership with the microbiota that is critical for metabolism, tissue development and host defense. Despite our growing understanding of the impact of this host-microbe alliance on immunity in the gastrointestinal tract, the extent to which individual microenvironments are controlled by resident microbiota remains unclear. In this Perspective, we discuss how resident commensals outside the gastrointestinal tract can control unique physiological niches and the potential implications of the dialog between these commensals and the host for the establishment of immune homeostasis, protective responses and tissue pathology. Références Abstract• References• Author information Shklovskaya, E. et al. Langerhans cells are precommitted to immune tolerance induction. Proc. Natl. Acad. Sci. USA 108, 18049–18054 (2011). PubMedArticle Chu, C.C. et al. Resident CD141 (BDCA3)+ dendritic cells in human skin produce IL-10 and induce regulatory T cells that suppress skin inflammation. J. Exp. Med. 209, 935–945 (2012). CASPubMedArticle Igyarto, B.Z. et al. Skin-resident murine dendritic cell subsets promote distinct and opposing antigen-specific T helper cell responses. Immunity 35, 260–272 (2011). CASISIPubMedArticle Scott, C.L., Aumeunier, A.M. & Mowat, A.M. Intestinal CD103+ dendritic cells: master regulators of tolerance? Trends Immunol. 32, 412–419 (2011). CASPubMedArticle Spits, H. & Cupedo, T. Innate lymphoid cells: emerging insights in development, lineage relationships, and function. Annu. Rev. Immunol. 30, 647–675 (2012). CASPubMedArticle Owens, B.M. & Simmons, A. Intestinal stromal cells in mucosal immunity and homeostasis. Mucosal Immunol. 6, 224–234 (2013). CASPubMedArticle Malhotra, D., Fletcher, A.L. & Turley, S.J. Stromal and hematopoietic cells in secondary lymphoid organs: partners in immunity. Immunol. Rev. 251, 160–176 (2013). CASPubMedArticle Matzinger, P. & Kamala, T. Tissue-based class control: the other side of tolerance. Nat. Rev. Immunol. 11, 221–230 (2011). CASISIPubMedArticle Hooper, L.V. & Macpherson, A.J. Immune adaptations that maintain homeostasis with the intestinal microbiota. Nat. Rev. Immunol. 10, 159–169 (2010). CASISIPubMedArticle Molloy, M.J., Bouladoux, N. & Belkaid, Y. Intestinal microbiota: shaping local and systemic immune responses. Semin. Immunol. 24, 58–66 (2012). CASPubMedArticle Blumberg, R. & Powrie, F. Microbiota, disease, and back to health: a metastable journey. Sci. Transl. Med. 4, 137rv137 (2012). CASArticle Smith, M.I. et al. Gut microbiomes of Malawian twin pairs discordant for kwashiorkor. Science 339, 548–554 (2013). CASADSPubMedArticle Foulongne, V. et al. Human skin microbiota: high diversity of DNA viruses identified on the human skin by high throughput sequencing. PLoS ONE 7, e38499 (2012). CASADSPubMedArticle Iliev, I.D. et al. Interactions between commensal fungi and the C-type lectin receptor Dectin-1 influence colitis. Science 336, 1314–1317 (2012). CASADSPubMedArticle Reyes, A. et al. Viruses in the faecal microbiota of monozygotic twins and their mothers. Nature 466, 334–338 (2010). CASADSISIPubMedArticle Eckburg, P.B., Lepp, P.W. & Relman, D.A. Archaea and their potential role in human disease. Infect. Immun. 71, 591–596 (2003). CASISIPubMedArticle Grice, E.A. & Segre, J.A. The human microbiome: our second genome. Annu. Rev. Genomics Hum. Genet. 13, 151–170 (2012). CASPubMedArticle Ley, R.E., Peterson, D.A. & Gordon, J.I. Ecological and evolutionary forces shaping microbial diversity in the human intestine. Cell 124, 837–848 (2006). CASISIPubMedArticle Medini, D. et al. Microbiology in the post-genomic era. Nat. Rev. Microbiol. 6, 419–430 (2008). CASPubMedArticle Kuczynski, J. et al. Experimental and analytical tools for studying the human microbiome. Nat. Rev. Genet. 13, 47–58 (2012). CASArticle Costello, E.K. et al. Bacterial community variation in human body habitats across space and time. Science 326, 1694–1697 (2009). CASADSISIPubMedArticle Eckburg, P.B. et al. Diversity of the human intestinal microbial flora. Science 308, 1635–1638 (2005). ADSISIPubMedArticle Qin, J. et al. A human gut microbial gene catalogue established by metagenomic sequencing. Nature 464, 59–65 (2010). CASISIPubMedArticle Lozupone, C.A., Stombaugh, J.I., Gordon, J.I., Jansson, J.K. & Knight, R. Diversity, stability and resilience of the human gut microbiota. Nature 489, 220–230 (2012). CASADSPubMedArticle Tilg, H. & Kaser, A. Gut microbiome, obesity, and metabolic dysfunction. J. Clin. Invest. 121, 2126–2132 (2011). CASPubMedArticle Tlaskalova-Hogenova, H. et al. The role of gut microbiota (commensal bacteria) and the mucosal barrier in the pathogenesis of inflammatory and autoimmune diseases and cancer: contribution of germ-free and gnotobiotic animal models of human diseases. Cell Mol. Immunol. 8, 110–120 (2011). CASPubMedArticle Pride, D.T. et al. Evidence of a robust resident bacteriophage population revealed through analysis of the human salivary virome. ISME J. 6, 915–926 (2012). CASPubMedArticle Human Microbiome Project Consortium. A framework for human microbiome research. Nature 486, 215–221 (2012). CASPubMedArticle Human Microbiome Project Consortium. Structure, function and diversity of the healthy human microbiome. Nature 486, 207–214 (2012). CASPubMedArticle Grice, E.A. & Segre, J.A. The skin microbiome. Nat. Rev. Microbiol. 9, 244–253 (2011). CASISIPubMedArticle Grice, E.A. et al. Topographical and temporal diversity of the human skin microbiome. Science 324, 1190–1192 (2009). CASADSISIPubMedArticle Segata, N. et al. Composition of the adult digestive tract bacterial microbiome based on seven mouth surfaces, tonsils, throat and stool samples. Genome Biol. 13, R42 (2012). CASPubMedArticle Beck, J.M., Young, V.B. & Huffnagle, G.B. The microbiome of the lung. Transl. Res. 160, 258–266 (2012). CASPubMedArticle Charlson, E.S. et al. Topographical continuity of bacterial populations in the healthy human respiratory tract. Am. J. Respir. Crit. Care Med. 184, 957–963 (2011). PubMedArticle Abubucker, S. et al. Metabolic reconstruction for metagenomic data and its application to the human microbiome. PLoS Comput. Biol. 8, e1002358 (2012). CASPubMedArticle Cantarel, B.L., Lombard, V. & Henrissat, B. Complex carbohydrate utilization by the healthy human microbiome. PLoS ONE 7, e28742 (2012). CASPubMedArticle Ichinohe, T. et al. Microbiota regulates immune defense against respiratory tract influenza A virus infection. Proc. Natl. Acad. Sci. USA 108, 5354–5359 (2011). ADSPubMedArticle Abt, M.C. et al. Commensal bacteria calibrate the activation threshold of innate antiviral immunity. Immunity 37, 158–170 (2012). CASPubMedArticle Ochoa-Reparaz, J. et al. Central nervous system demyelinating disease protection by the human commensal Bacteroides fragilis depends on polysaccharide A expression. J. Immunol. 185, 4101–4108 (2010). CASPubMedArticle Wu, H.J. et al. Gut-residing segmented filamentous bacteria drive autoimmune arthritis via T helper 17 cells. Immunity 32, 815–827 (2010). CASISIPubMedArticle Berer, K. et al. Commensal microbiota and myelin autoantigen cooperate to trigger autoimmune demyelination. Nature 479, 538–541 (2011). CASADSISIPubMedArticle Wen, L. et al. Innate immunity and intestinal microbiota in the development of type 1 diabetes. Nature 455, 1109–1113 (2008). CASADSISIPubMedArticle Kriegel, M.A. et al. Naturally transmitted segmented filamentous bacteria segregate with diabetes protection in nonobese diabetic mice. Proc. Natl. Acad. Sci. USA 108, 11548–11553 (2011). ADSPubMedArticle Hill, D.A. et al. Commensal bacteria-derived signals regulate basophil hematopoiesis and allergic inflammation. Nat. Med. 18, 538–546 (2012). CASPubMedArticle Clarke, T.B. et al. Recognition of peptidoglycan from the microbiota by Nod1 enhances systemic innate immunity. Nat. Med. 16, 228–231 (2010). CASISIPubMedArticle Shi, C. et al. Bone marrow mesenchymal stem and progenitor cells induce monocyte emigration in response to circulating toll-like receptor ligands. Immunity 34, 590–601 (2011). CASPubMedArticle Maslowski, K.M. et al. Regulation of inflammatory responses by gut microbiota and chemoattractant receptor GPR43. Nature 461, 1282–1286 (2009). CASADSISIPubMedArticle Kong, H.H. et al. Temporal shifts in the skin microbiome associated with disease flares and treatment in children with atopic dermatitis. Genome Res. 22, 850–859 (2012). CASPubMedArticle Abreu, N.A. et al. Sinus microbiome diversity depletion and Corynebacterium tuberculostearicum enrichment mediates rhinosinusitis. Sci. Transl. Med. 4, 151ra124 (2012). CASPubMedArticle Hilty, M. et al. Disordered microbial communities in asthmatic airways. PLoS ONE 5, e8578 (2010). CASADSPubMedArticle Belda-Ferre, P. et al. The oral metagenome in health and disease. ISME J. 6, 46–56 (2012). CASPubMedArticle Srinivasan, S. et al. Temporal variability of human vaginal bacteria and relationship with bacterial vaginosis. PLoS ONE 5, e10197 (2010). CASPubMedArticle Crispe, I.N. The liver as a lymphoid organ. Annu. Rev. Immunol. 27, 147–163 (2009). CASISIPubMedArticle Corbitt, N. et al. Gut bacteria drive Kupffer cell expansion via MAMP-mediated ICAM-1 induction on sinusoidal endothelium and influence preservation-reperfusion injury after orthotopic liver transplantation. Am. J. Pathol. 182, 180–191 (2013). CASPubMedArticle Bigorgne, A.E. & Crispe, I.N. TLRs in hepatic cellular crosstalk. Gastroenterol. Res. Pract. 2010, 618260 (2010). PubMed Lunz, J.G. III, Specht, S.M., Murase, N., Isse, K. & Demetris, A.J. Gut-derived commensal bacterial products inhibit liver dendritic cell maturation by stimulating hepatic interleukin-6/signal transducer and activator of transcription 3 activity. Hepatology 46, 1946–1959 (2007). CASPubMedArticle Wilson, N.S. et al. Normal proportion and expression of maturation markers in migratory dendritic cells in the absence of germs or Toll-like receptor signaling. Immunol. Cell Biol. 86, 200–205 (2008). CASPubMedArticle Walton, K.L., He, J., Kelsall, B.L., Sartor, R.B. & Fisher, N.C. Dendritic cells in germ-free and specific pathogen-free mice have similar phenotypes and in vitro antigen presenting function. Immunol. Lett. 102, 16–24 (2006). CASPubMedArticle Hill, D.A. et al. Metagenomic analyses reveal antibiotic-induced temporal and spatial changes in intestinal microbiota with associated alterations in immune cell homeostasis. Mucosal Immunol. 3, 148–158 (2009). CASISIPubMedArticle Grice, E.A. et al. A diversity profile of the human skin microbiota. Genome Res. 18, 1043–1050 (2008). CASISIPubMedArticle Christoph, T. et al. The human hair follicle immune system: cellular composition and immune privilege. Br. J. Dermatol. 142, 862–873 (2000). CASISIPubMedArticle Nagao, K. et al. Stress-induced production of chemokines by hair follicles regulates the trafficking of dendritic cells in skin. Nat. Immunol. 13, 744–752 (2012). CASPubMedArticle Iwase, T. et al. Staphylococcus epidermidis Esp inhibits Staphylococcus aureus biofilm formation and nasal colonization. Nature 465, 346–349 (2010). CASADSISIPubMedArticle Gallo, R.L. & Hooper, L.V. Epithelial antimicrobial defence of the skin and intestine. Nat. Rev. Immunol. 12, 503–516 (2012). CASPubMedArticle Cash, H.L., Whitham, C.V., Behrendt, C.L. & Hooper, L.V. Symbiotic bacteria direct expression of an intestinal bactericidal lectin. Science 313, 1126–1130 (2006). CASADSISIPubMedArticle Naik, S. et al. Compartmentalized control of skin immunity by resident commensals. Science 337, 1115–1119 (2012). CASADSPubMedArticle Lai, Y. et al. Commensal bacteria regulate Toll-like receptor 3–dependent inflammation after skin injury. Nat. Med. 15, 1377–1382 (2009). CASISIPubMedArticle Loots, M.A. et al. Differences in cellular infiltrate and extracellular matrix of chronic diabetic and venous ulcers versus acute wounds. J. Invest. Dermatol. 111, 850–857 (1998). CASISIPubMedArticle Grice, E.A. et al. Longitudinal shift in diabetic wound microbiota correlates with prolonged skin defense response. Proc. Natl. Acad. Sci. USA 107, 14799–14804 (2010). ADSPubMedArticle Ivanov, I.I. et al. Induction of intestinal Th17 cells by segmented filamentous bacteria. Cell 139, 485–498 (2009). CASISIPubMedArticle Gallo, R.L. & Nakatsuji, T. Microbial symbiosis with the innate immune defense system of the skin. J. Invest. Dermatol. 131, 1974–1980 (2011). CASISIPubMedArticle Kong, H.H. et al. Temporal shifts in the skin microbiome associated with disease flares and treatment in children with atopic dermatitis. Genome Res. 22, 850–859 (2012). CASPubMedArticle Gao, Z., Tseng, C.H., Strober, B.E., Pei, Z. & Blaser, M.J. Substantial alterations of the cutaneous bacterial biota in psoriatic lesions. PLoS ONE 3, e2719 (2008). CASADSPubMedArticle Sims, J.E. & Smith, D.E. The IL-1 family: regulators of immunity. Nat. Rev. Immunol. 10, 89–102 (2010). CASISIPubMedArticle Nestle, F.O., Kaplan, D.H. & Barker, J. Psoriasis. N. Engl. J. Med. 361, 496–509 (2009). CASISIPubMedArticle Ortega, C. et al. IL-17-producing CD8+ T lymphocytes from psoriasis skin plaques are cytotoxic effector cells that secrete TH17-related cytokines. J. Leukoc. Biol. 86, 435–443 (2009). CASISIPubMedArticle Eyerich, S. et al. Th22 cells represent a distinct human T cell subset involved in epidermal immunity and remodeling. J. Clin. Invest. 119, 3573–3585 (2009). CASISIPubMed Leonardi, C. et al. Anti-interleukin-17 monoclonal antibody ixekizumab in chronic plaque psoriasis. N. Engl. J. Med. 366, 1190–1199 (2012). CASPubMedArticle Papp, K.A. et al. Brodalumab, an anti-interleukin-17-receptor antibody for psoriasis. N. Engl. J. Med. 366, 1181–1189 (2012). CASPubMedArticle Zheng, Y. et al. Interleukin-22, a TH17 cytokine, mediates IL-23–induced dermal inflammation and acanthosis. Nature 445, 648–651 (2007). CASISIPubMedArticle Lai, Y. et al. The antimicrobial protein REG3A regulates keratinocyte proliferation and differentiation after skin injury. Immunity 37, 74–84 (2012). CASPubMedArticle Avila, M., Ojcius, D.M. & Yilmaz, O. The oral microbiota: living with a permanent guest. DNA Cell Biol. 28, 405–411 (2009). CASPubMedArticle Yilmaz, O. The chronicles of Porphyromonas gingivalis: the microbium, the human oral epithelium and their interplay. Microbiology 154, 2897–2903 (2008). CASPubMedArticle Dixon, D.R., Reife, R.A., Cebra, J.J. & Darveau, R.P. Commensal bacteria influence innate status within gingival tissues: a pilot study. J. Periodontol. 75, 1486–1492 (2004). PubMedArticle Desvarieux, M. et al. Periodontal microbiota and carotid intima-media thickness: the oral infections and vascular disease epidemiology study (INVEST). Circulation 111, 576–582 (2005). ISIPubMedArticle Hajishengallis, G. et al. Low-abundance biofilm species orchestrates inflammatory periodontal disease through the commensal microbiota and complement. Cell Host Microbe 10, 497–506 (2011). CASPubMedArticle Egan, C.E., Cohen, S.B. & Denkers, E.Y. Insights into inflammatory bowel disease using Toxoplasma gondii as an infectious trigger. Immunol. Cell Biol. 90, 668–675 (2012). CASPubMedArticle Heimesaat, M.M. et al. Gram-negative bacteria aggravate murine small intestinal Th1-type immunopathology following oral infection with Toxoplasma gondii. J. Immunol. 177, 8785–8795 (2006). CASISIPubMed Lupp, C. et al. Host-mediated inflammation disrupts the intestinal microbiota and promotes the overgrowth of Enterobacteriaceae. Cell Host Microbe 2, 204 (2007). CASISIPubMedArticle Stecher, B. et al. Salmonella enterica serovar typhimurium exploits inflammation to compete with the intestinal microbiota. PLoS Biol. 5, 2177–2189 (2007). CASISIPubMedArticle Farage, M. & Maibach, H. Lifetime changes in the vulva and vagina. Arch. Gynecol. Obstet. 273, 195–202 (2006). PubMedArticle Hickey, R.J., Zhou, X., Pierson, J.D., Ravel, J. & Forney, L.J. Understanding vaginal microbiome complexity from an ecological perspective. Transl. Res. 160, 267–282 (2012). CASPubMedArticle Antonio, M.A., Hawes, S.E. & Hillier, S.L. The identification of vaginal Lactobacillus species and the demographic and microbiologic characteristics of women colonized by these species. J. Infect. Dis. 180, 1950–1956 (1999). CASISIPubMedArticle Spurbeck, R.R. & Arvidson, C.G. Lactobacilli at the front line of defense against vaginally acquired infections. Future Microbiol. 6, 567–582 (2011). CASPubMedArticle Rose, W.A. II et al. Commensal bacteria modulate innate immune responses of vaginal epithelial cell multilayer cultures. PLoS ONE 7, e32728 (2012). CASADSPubMedArticle Zhou, X. et al. Characterization of vaginal microbial communities in adult healthy women using cultivation-independent methods. Microbiology 150, 2565–2573 (2004). CASISIPubMedArticle Witkin, S.S., Alvi, S., Bongiovanni, A.M., Linhares, I.M. & Ledger, W.J. Lactic acid stimulates interleukin-23 production by peripheral blood mononuclear cells exposed to bacterial lipopolysaccharide. FEMS Immunol. Med. Microbiol. 61, 153–158 (2011). CASPubMedArticle Genc, M.R. et al. Polymorphism in intron 2 of the interleukin-1 receptor antagonist gene, local midtrimester cytokine response to vaginal flora, and subsequent preterm birth. Am. J. Obstet. Gynecol. 191, 1324–1330 (2004). CASPubMedArticle Gabryszewski, S.J. et al. Lactobacillus-mediated priming of the respiratory mucosa protects against lethal pneumovirus infection. J. Immunol. 186, 1151–1161 (2011). CASPubMedArticle Garcia-Crespo, K.E. et al. Lactobacillus priming of the respiratory tract: heterologous immunity and protection against lethal pneumovirus infection. Antiviral Res. 97, 270–279 (2013). CASPubMedArticle Herbst, T. et al. Dysregulation of allergic airway inflammation in the absence of microbial colonization. Am. J. Respir. Crit. Care Med. 184, 198–205 (2011). CASPubMedArticle Hand, T.W. et al. Acute gastrointestinal infection induces long-lived microbiota-specific T cell responses. Science 337, 1553–1556 (2012). CASADSPubMedArticle Haas, A. et al. Systemic antibody responses to gut commensal bacteria during chronic HIV-1 infection. Gut 60, 1506–1519 (2011). CASISIPubMedArticle
Repost 0
Published by Chronimed - dans Infections froides
commenter cet article
10 juillet 2013 3 10 /07 /juillet /2013 06:40
The microbial communities that colonize living organisms are collectively referred to as the 'microbiota'. These resident commensals are well adapted to the ecological conditions of their host and constitute a complex ecosystem in which host-microbe, environment-microbe and microbe-microbe interactions dictate the composition and dynamics of the community. As with every ecosystem, commensal species occupy a niche, are evolutionarily adapted and continuously selected by the environmental pressures in the niche, and compete with other species for niche resources. In mammals, the gut microbiota has coevolved to provide essential functions for host physiological processes, such as the acquisition of nutrients, the development and maturation of the immune system and enhancement of the intestinal barrier. In this issue of Nature Immunology, we provide a series of specially commissioned articles to discuss recent advances on the understanding of the complex relationship between the microbiota and the host immune system (http://www.nature.com/ni/focus/microbiota). The gastrointestinal tract contains the most abundant commensal community in mammals. However, other anatomical sites are colonized by unique communities of bacteria, with their structure and composition determined by their unique environment. In their Perspective, Belkaid and Naik review the present understanding of the physiological impact of resident commensals in the skin as well as the oral, vaginal and airway mucosa. In contrast to the dominant role of the gut microbiota, which can control the development of the immune system and set systemic thresholds for immune activation, the microbiota at sites other than the gut has a more local and discrete influence on processes such as tissue homeostasis, immune responses and tissue repair. Whereas recent efforts have generated a wealth of information on the composition of host-associated bacterial communities, much less is known about the viruses that colonize healthy people (the so-called 'virobiota') or the effect of viral genes (the 'virome') on host immunity. Study of the virobiota is an emerging field, and understanding of virobiota–immune system interactions is very preliminary. In their Perspective, Duerkop and Hooper provide a framework for considering how resident viruses associated with either the bacterial commensals (phages) or the host cells can shape microbiota communities and influence host immunity. Four commissioned Reviews discuss the complex interactions between the gut microbiota and the immune system. Despite the beneficial aspects of microbial colonization of the intestine, the abundance and proximity of such microbes to the host epithelium poses a major challenge to host integrity. Finlay and colleagues review the strategies used by the immune system to confine the microbial community in the lumen of the intestinal tract and achieve homeostasis. These include physical and biochemical barriers (the mucus layer, secretion of antimicrobial peptides and immunoglobulin A), as well as continuous surveillance by cellular and molecular components of the innate and adaptive immune system. This Review also discusses how environmental triggers, such as dietary changes, gastrointestinal pathogens or antibiotic treatment, or host-related factors, such as genetic susceptibility or immunodeficiency, can lead to a breakdown in host-microbe mutualism. Chu and Mazmanian cover recent research on the symbiotic relationship between invertebrate or vertebrate hosts and their bacterial communities and suggest that pattern-recognition receptors may have evolved to mediate the bidirectional cross-talk between microbial symbionts and their hosts. From Hydra to humans, these authors provide examples that highlight the role of these receptors in mediating the recognition of commensals and shaping the composition of microbiota, as well as in inducing tolerance toward symbiotic bacteria through local and systemic responses. Finally, two Reviews discuss how various aspects of microbiota activity can influence host metabolism and immune function. Commensal bacteria regulate the production and bioavailability of diet-dependent nutrients and metabolites such as bile acids, short-chain fatty acids and vitamins. Brestoff and Artis discuss how such commensal-derived products modulate the development and function of the immune system in health and disease. The commensal microbiota also protects against colonization by pathogens. Nuñez and colleagues highlight several mechanisms by which such interactions take place, such as competitive metabolic interactions and colonization of intestinal niches. A question central to understanding the complex interactions between host and microbiota is how the immune system distinguishes between commensals and pathogens. All bacteria, tolerated or not, share the same molecular patterns and are sensed by the same recognition pathways and receptors. The common opinion presented in this Focus is that recognition of pathogens versus commensals is not 'hard-wired' in the host immune system. The process is instead one of education. Hosts learn to recognize, restrain and tolerate their bacterial commensals. Through birth, breastfeeding and social interactions, mammals inherit a preselected community of microbes that is able to integrate into the physiological and homeostatic requirements of its host. Both the microbiota and the host use tools and signals shaped by millions of years of coevolution to maintain a constant dialog and a mutualistic relationship. As with any relationship, things can go wrong. Small imbalances introduced by the host's genetic makeup and/or various triggers, such as recurrent immune responses or microbial dysbiosis, can over time disturb the dynamic equilibrium between host and commensals. In such circumstances, the microbiota can become an amplifier of pathological effects and can feed forward into deregulated pathways that lead to local or systemic disease. As this exciting area of research blossoms, it becomes more and more apparent that studies of the immune system during homeostasis or disease cannot ignore the microbial world within.
Repost 0
Published by Chronimed - dans Infections froides
commenter cet article
9 juillet 2013 2 09 /07 /juillet /2013 23:29
« les cellules adipeuses contiennent des gènes qui, lorsqu'ils s'expriment, favorisent de nombreuses maladies telles que le diabète et l'obésité », et fait savoir que « des chercheurs suédois ont cherché à savoir s'il était possible de modifier favorablement, grâce à la pratique régulière d'un sport, l'expression des gènes des cellules adipeuses ». « ont enrôlé 30 hommes, initialement peu actifs, proches de la quarantaine. La moitié d'entre eux avaient des antécédents familiaux de diabète. […] Une biopsie de graisse abdominale a été réalisée au début de l'étude puis 6 mois plus tard, et le niveau d'expression des gènes mesuré par la méthylation de l'ADN, synonyme de blocage de l'activité ». « Les résultats, publiés dans la revue PLOS Genetics, confirment l'amélioration attendue », observe le Pr Charlotte Ling, de l'Université de Lund (Malmö) : « C'est la première fois que l'on démontre que l'exercice physique, à raison de 2 séances par semaine pendant 6 mois, peut modifier la méthylation de plus de 7.000 gènes contenus dans les cellules adipeuses d'hommes d'âge moyen ». « Une amélioration qui se voit aussi dans des paramètres plus classiques, ajoute la chercheuse : «Réduction du rapport taille-hanches, augmentation de la condition physique, diminution de la pression artérielle et de la fréquence cardiaque» ». « pour le Pr Philippe Amouyel, directeur de l'unité Inserm Santé publique et épidémiologie moléculaire des maladies liées au vieillissement (CHU de Lille), «le profil de risque cardiovasculaire s'améliore indéniablement», mais il est trop tôt pour tirer des conclusions en ce qui concerne les modifications observées sur les gènes impliqués dans l'obésité et le diabète ».
Repost 0
Published by Chronimed - dans Concept
commenter cet article
9 juillet 2013 2 09 /07 /juillet /2013 22:55
étude suédoise publiée dans le Jama. « Ayant suivi près de 2,5 millions d’enfants nés entre 1982 et 2007, les chercheurs révèlent que le risque d’autisme et de retard mental est légèrement accru chez les enfants nés grâce à certains procédés de fécondation in vitro ». « Il en est ainsi de l’ICSI (injection intracytoplasmique de sperme), une technique qui vise à traiter l’infertilité masculine en injectant directement en laboratoire le spermatozoïde dans l’ovule. […] D’après les chercheurs, les enfants nés après une ICSI ont un risque de présenter un autisme de 0,136%, contre 0,029% pour les enfants conçus naturellement ». Sven Sandin, coauteur de ce travail, indique que « lorsqu’on examine les traitements dans leur ensemble, on ne constate pas d’augmentation du risque d’autisme. Par contre, lorsqu’on distingue les techniques, on voit que le recours à l’ICSI augmente à la fois le retard mental et l’autisme ». Le Pr Jean-Pierre Siffroi, généticien à l’hôpital Armand-Trousseau et spécialiste de la procréation médicalement assistée, précise toutefois que « même si l’augmentation est significative, le risque reste infime en valeur absolue ». « les scientifiques s’avouent incapables d’expliquer le mécanisme », le Pr Siffroi remarquant qu’« il n’est pas exclu que la manipulation des gamètes et des embryons dans des conditions artificielles perturbe le processus épigénétique, causant certaines pathologies ». « Selon les chercheurs, ce léger surrisque peut, au moins en partie, être attribué aux naissances multiples et prématurées, qui sont plus fréquentes en cas de FIV, et non à la technique en elle-même ».
Repost 0
Published by Chronimed - dans Concept
commenter cet article
9 juillet 2013 2 09 /07 /juillet /2013 19:30
Que le comportement et les acquisitions évoluent au cours de l’enfance, rien de nouveau. Comprendre comment l’épigénétique intervient dans le processus en revanche est inédit. Une équipe californienne du Salk Institute for Biological Studies en collaboration avec l’Université de Barcelone vient de décrire comment l’extinction ou l’allumage des gènes, via la méthylation de l’ADN, se met en place au cours du développement. Ce processus se modifie profondément au niveau du cortex frontal de la naissance à la fin de l’adolescence, traduisant l’établissement d’un nouveau réseau de communication synaptique. La méthylation régule les synapses Pour obtenir ces résultats, les chercheurs ont comparé les sites exacts de méthylation dans l’ensemble du génome cérébral à différents âges de la vie, chez des nouveau-nés, des adolescents âgés de 16 ans et des adultes âgés de 25 à 50 ans. Le phénomène augmente progressivement jusqu’à l’entrée à l’âge adulte. « La méthylation de l’ADN joue un rôle clef dans le profil de communication synaptique, explique l’un des auteurs, le Dr Manuel Esteller de l’université de Barcelone. (...) Les formes de méthylation de l’ADN font la distinction avec les gènes spécifiques d’une activité cellulaire. Même dans la matière grise, il existe des sous-types cellulaires comme les neurones pyramidaux et les cellules à GABA qui présentent des profils spécifiques de méthylation de l’ADN. » Une forme spécifique « non-CG » Les chercheurs ont découvert qu’il existe une forme de méthylation dans les neurones et la glie dès la naissance. Plus surprenant, ils ont montré également qu’une seconde forme dite « non-CG » quasi exclusive aux neurones s’accumule au fur et à mesure de la maturation cérébrale, devenant ensuite la forme dominante dans le génome neuronal. « C’est comme mettre un accent grave ou aigu sur un mot, dans notre cas sur un gène pour en changer le sens », explique le scientifique. Jusqu’à présent, on pensait que la méthylation « non-CG » était réservée aux cellules souches et disparaissait avec leur différenciation. Le rôle de l’épigénétique en psychiatrie Ces résultats pourraient expliquer non seulement le phénomène de plasticité cérébrale au fil des expériences de la vie mais aussi aider à comprendre certaines maladies psychiatriques. Il existe un consensus parmi les neuroscientifiques pour penser que certains troubles mentaux sont la résultante d’une prédisposition génétique avec des facteurs environnementaux. La méthylation de l’ADN pourrait être l’un d’entre eux. « Nous devons chercher à déterminer dans quelle mesure des altérations mineures dans le programme de méthylation de l’ADN au cours du développement postnatal précoce peuvent être associées à des troubles neuropsychiatriques comme l’autisme ou la schizophrénie », poursuit le chercheur. Dr IRÈNE DROGOU 08/07/2013
Repost 0
Published by Chronimed - dans Concept
commenter cet article
9 juillet 2013 2 09 /07 /juillet /2013 07:18
L’arthrose (OA) comprend initialement une résorption osseuse sous chondrale qui entraîne une sclérose sous chondrale et la formation d’ostéophytes. Ces modifications du turnover osseux résultent d’une augmentation de l’activité des ostéoclastes et des ostéoblastes. Or, le système ostéoprotégérine (OPG)/ RANK /RANKL est au centre de cette activité. Par ailleurs des molécules associées à la douleur ont été détectées dans l’os sous chondral de l’articulation arthrosique. Dans ce travail expérimental, les auteurs ont supposé que l’OPG pourrait, en inhibant l’ostéoclastogénèse et le turnover osseux prévenir la douleur dans un modèle d’OA chez le rat. Cent quatre rats males ont été utilisés pour cette expérience. Les lésions articulaires ont été induites par une injection intra articulaire de MIA (monosodium iodoacétate) tandis que les animaux contrôles recevaient une injection intra articulaire de sérum physiologique. Deux mesures de comportements douloureux ont été évaluées : l’asymétrie des membres postérieurs, témoin de l’hyperalgie et le retrait de la patte, témoin de la l’allodynie. Les rats ont été randomisés dans différents groupes de traitement. Le groupe « traitement préventif » a reçu des injections sous cutanées d’OPG ou d’un placebo de J1 à J27 après l’injection intra articulaire de MIA. Le groupe « traitement curatif » a bénéficié d injections sous cutanées de placebo de J1 à J20 puis d’injections d’OPG à partir de J27.Le groupe traitement préventif par zolédronate (ZOL) a eu des injections sous cutanées de ZOL de J1 à J25. Les rats contrôles (sérum physiologique) ont reçu un placebo. A la fin de l’étude, les rats ont été sacrifiés et l’articulation tibio fémorale analysée. Le traitement préventif par OPG a diminué l’hyperalgie mais pas l’allodynie et s’est accompagné d’une réduction du nombre des ostéoclastes, de la synovite, des lésions cartilagineuses et du nombre d’ostéophytes. Le traitement par ZOL a diminué l’hyperalgie, la synovite, les dégradations cartilagineuses et le nombre d’ostéophytes, mais pas l’allodynie ni le nombre d’ostéoclastes. Le traitement curatif par OPG a réduit l’hyperalgie, le nombre d’ostéoclastes mais n’a pas eu d’effet sur l’allodynie, la synovite, les dégradations cartilagineuses ou le nombre d’ostéophytes. Le turnover de l’os sous chondral semble donc particulièrement important dans les premières phases de l’OA. Il serait probablement pertinent de favoriser les essais thérapeutiques ciblant l’ostéoclaste. Dr Juliette Lasoudris Laloux 05/07/2013 Devi Rani Sagar et coll.: Osteoprotegerin reduces the development of pain behaviour and joint pathology in a model of osteoarthritis. Ann Rheum Dis., 2013; publication avancée en ligne le 30 mai.
Repost 0
Published by Chronimed - dans Concept
commenter cet article
9 juillet 2013 2 09 /07 /juillet /2013 06:55
Aux Etats-Unis, les boissons sucrées (BS) représentent la principale source de sucre ajouté aussi bien chez les enfants que chez les adultes. Si la consommation de BS a été clairement associée à l’obésité, le lien de cause à effet fait encore débat. L’objectif ambitieux des auteurs est de clore celui-ci à travers une revue de la des études prospectives et des essais randomisés et contrôlés (ERC) de la littérature. En clair, dispose-t-on de preuves scientifiques suffisantes pour affirmer qu’une diminution de la consommation de BS (sodas et jus) réduirait la prévalence de l‘obésité ? Les résultats issus d’études prospectives rigoureuses et de longues durées ont montré de manière systématique une association significative et dose dépendante entre consommation de BS et prise de poids à long terme. A titre d’exemple, chez les adultes, la consommation de BS est associée à une prise de 8 kg sur 8 ans (Schulze et al., JAMA 2004)ou bien encore la consommation d’une cannette supplémentaire par jour est associée à une prise de 0,5 kg tous les 4 ans (Mozaffarian et al., NEJM 2011). Chez les enfants, les plus gros consommateurs de BS augmentent leur risque de devenir obèse de 55 % par rapport aux plus faibles consommateurs (Morgenga et al. BMJ 2012). Les ERC sont peu nombreuses mais viennent confirmer dans leur majorité les résultats des études prospectives. Cependant ces essais présentent des limites méthodologiques évidentes (échantillons, durées courtes, taux d’attrition élevé..), mais deux ERC très récents menés de manière rigoureuse et à grande échelle ont montré une diminution significative du poids dans le groupe d’intervention (eau ou boisson light) par rapport au groupe contrôle (poursuite de la consommation de BS) . L’une d’elles (De Ruyter et al., NEJM 2012), a montré qu’une réduction de 104 kcal/j issue des BS (soit 250 ml/j) freinait la prise poids de 1,01 kg en 18 mois chez des enfants de poids normal. Ces 2 types de preuves, issues d’une part d’études prospectives à long terme et d’autre part d’ERC à court terme, sont complémentaires. Elles sont suffisantes pour établir une relation de cause à effet entre BS et obésité selon les auteurs (qui se basent sur les critères de Bradford Hill pour établir de manière détaillée ce lien de causalité). Qu’en est-il de l’amplitude de la perte de poids associée à la baisse de la consommation de BS ? Elle n’a pas été chiffrée mais elle reste clairement modeste. Cela s’explique par le fait que l’unité d’exposition aux BS utilisée dans les études est petite (250 ml en moyenne). Par conséquent on peut s’attendre à des bénéfices plus importants chez les gros consommateurs tels que les adolescents et les obèses ! Dr Rodi Courie 08/07/2013 Hu FB et coll. : Resolved: there is sufficient scientific evidence that decreasing sugar-sweetened beverage consumption will reduce the prevalence of obesity and obesity-related diseases. Obes Rev., 2013; publication avancée en ligne le 13 juin. doi: 10.1111/obr.12040.
Repost 0
Published by Chronimed - dans Nutrition
commenter cet article
9 juillet 2013 2 09 /07 /juillet /2013 06:49
Le risque de suicide est 10 fois plus élevé chez les sujets présentant des troubles de l’humeur que dans la population ne souffrant pas de pathologie psychiatrique, que le trouble soit unipolaire (épisodes dépressifs) ou bipolaires (manie ou hypomanie avec épisodes dépressifs intermittents). Les traitements médicamenteux n’ont jusqu’à présent qu’un rôle limité dans la prévention du suicide. Une équipe italienne avait démontré que le lithium au long cours était plus efficace que le placebo ou que d’autres molécules dans une stratégie de prévention du suicide chez ce type de patients. Mais de nombreuses incertitudes demeuraient quant à l’estimation de cette efficacité. La même équipe vient de publier les résultats d’une nouvelle méta-analyse intégrant les essais publiés depuis leur précédente étude. Au total 48 essais ont été retenus, incluant 6 674 participants, et l’analyse des résultats confirme que le lithium est plus efficace que le placebo sur la réduction du nombre de suicides (Odds ratio [OR]: 0,13, intervalle de confiance à 95 % [IC] : 0,03 à 0,66) et de décès toutes causes confondues (OR : 0,38 ; IC : 0,15 à 0,95). Mais si l’efficacité du lithium dans les troubles bipolaires ne constitue pas une réelle surprise, cette étude montre qu’il est aussi plus efficace que le placebo dans les troubles dépressifs unipolaires (0,36 ; 0,13 à 0,98). Il n’est pas démontré en revanche que le lithium soit plus bénéfique que les autres molécules utilisées dans ces indications pour la prévention du suicide ou des décès toutes causes. L’efficacité du lithium pour la prévention du suicide pourrait passer par la réduction du risque de rechutes, ou par un effet de diminution de l’agressivité et de l’impulsivité. Mais selon les auteurs, un effet spécifique du lithium sur le risque suicidaire ne peut être exclu. Dr Roseline Péluchon 03/07/2013 Cipriani A. et coll. : Lithium in the prevention of suicide in mooddisorders: updated systematic review and meta-analysis. BMJ 2013; 346: f3646doi: 10.1136/bmj.f3646.
Repost 0
Published by Chronimed - dans Concept
commenter cet article
3 juillet 2013 3 03 /07 /juillet /2013 09:52

New Tick-Borne Illness Could Be Worse Than Lyme Disease

Doctors May Not Even Know To Look For Borrelia Miyamotoi Infection

 

NEW YORK (CBSNewYork) — A new disease spread by deer ticks has already infected 100,000 New Yorkers since the state first started keeping track.

As CBS 2’s Dr. Max Gomez reported, the new deer tick-borne illness resembles Lyme disease, but is a different malady altogether – and it could be even worse.

The common deer tick is capable of spreading dangerous germs into the human bloodstream with its bite. However, Lyme disease is one of many diseases that ticks carry.

The latest disease is related to Lyme, and an infected person will suffer similar symptoms.

“Patients with this illness will develop, perhaps, fever, headache, flu-like symptoms, muscle pains — so they’ll have typical Lyme-like flu symptoms in the spring, summer, early fall,” said Dr. Brian Fallon of Columbia University. “But most of them will not develop the typical rash that you see with Lyme disease.”

Fallon, a renowned expert on Lyme disease at the New York Psychiatric Institute, said the importance of the new bacterium – called Borrelia miyamotoi — is that it might explain cases of what looked like chronic Lyme disease, but did not test positive for Lyme.

“The problem is that the diagnosis is going to be missed, because doctors aren’t going to think about Borrelia miyamotoi because they don’t know about it. 

And number two, if they test for Lyme disease, it will test negative, and the rash won’t be there,” Fallon said. 

“So they are not going to treat with the antibiotics, so the patient will have an infection staying in their system longer than it should.

While there is no test yet for the germ, the good news is that it appears the same antibiotic that kills Lyme disease also works – if it is given in the right doses and started early in the infection.

Remember, it takes a tick bite to get Lyme disease or the new bug, and the tick usually has to feed on your blood for at least 24 hours.

If you have been outdoors, have someone else do a full body check, Gomez advised. Ticks are small – only about the size of a sesame seed.

 

 

http://newyork.cbslocal.com/2013/07/02/new-tick-borne-illness-could-be-worse-than-lyme-disease/

Repost 0
Published by Chronimed - dans Infections froides
commenter cet article