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GUT MICROFLORA HAVE TO BE MODERNLY CONSIDERED A “MICROMIAL ORGAN” PLACED WITHIN A HOST ORGAN.

GUT MICROFLORA HAVE TO BE MODERNLY CONSIDERED A “MICROMIAL ORGAN” PLACED WITHIN A HOST ORGAN.

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GUT MICROFLORA HAVE TO BE MODERNLY CONSIDERED A “MICROMIAL ORGAN” PLACED WITHIN A HOST ORGAN.

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  1. GUT MICROFLORA HAVE TO BE MODERNLY CONSIDERED A “MICROMIAL ORGAN” PLACED WITHIN A HOST ORGAN.

  2. The intestinal habitat of an individual contains 300-500 different species of bacteria, and the number of microbial cells within the gut lumen is about 10 times larger than the number of eukariotic cells in the human body. Bengmark S. Gut 1998 Gastric acid, bile and pancreatic secretion kill most ingested microorganisms. The large intestine contains a complex and dynamic microbial ecosystem with high densities of living bacteria which achieve concentrations of up to 1012or 1013 cells/g of luminal contents. Simon GL. Gastroenterology 1984

  3. Czarniecki M. J Med Chem 2008

  4. A large proportion of the faecal mass consists of bacteria (around 60%). Stephen AM, Cummings JH. J.Med.Microbiol. Some of these bacteria are potential pathogens. However, the presence of bacterial competition and the constant interation between the host and its microbial guests can infer important health benefits to the human host. Salminen S et al. Br J Nutr1998.

  5. COMPOSITION OF THE FLORA -Colonization of the gastrointestinal tract starts immediately after birth, occurs within a few days, and it is linked to the type of delivery, the type of diet and environmental factors. -Pioneer bacteria can modulate expression of genes in host epithelial cells, thus creating a favourable habitat for themselves, and can prevent growth of other bacteria in the ecosystem. The initial colonisation is therefore very relevant to the final composition of the permanent flora. Hooper LV et al. Science 2001 -Resident bacteria deliver regulatory signals to the epithelium and instruct mucosal immune response. O’hara AM. Sci World J 2007

  6. Anaerobic bacteria outnumber aerobic bacteria by a factor of 100-1000. The genera bacterioides, bifidobacterium, eubacterium, clostridium, peptococcus,peptostreptococcus, and ruminococcus are predominant in human beings, whereas aerobes(facultative anaerobe) such as escherichia, enterobacter, enterococcus, klebsiella, lactobacillus, proteus, etc are among the subdominant genera. Salminen S. Br J Nutr 1998 Every individual presents a particular combination of predominant species that is distinct from that found in other individuals. Although bacterial composition can fluctuate under some circumstances (acute diarrhoeal illnesses, antibiotic treatment, dietary interventions), individuals’ flora composition pattern usually remain constant. Willson kh. Appl Environ Microbiol 1996

  7. Several bacteria that can be seen by direct microscopic examination of diluted faecal specimens cannot be grown in culture media: 40-80% of total microscopic counts are not recoverable by culture, although estimates vary between individuals and between studies. Suau A et al. Appl Environ Microbiol 1999 Molecular biological procedures can now be used to investigate the microbial ecology in the colon. Many DNA sequences correspond to previously undescribed bacteria and data suggest that every individual has unique strains of bacteria. Tannock GW. Am J Clin Nutr 2001

  8. LA METAGENOMICA E' UN APPROCCIO BASATO SULL'UTILIZZO DI TECNICHE GENOMICHE MODERNE PER LO STUDIO DI COMUNITA' MICROBICHE DIRETTAMENTE NEL LORO AMBIENTE NATURALE, EVITANDO IL PRELIEVO E LA COLTURA IN LABORATORIO. SI BASA SUL SEQUENZIAMENTO DEL GENOMA DI MICROORGANISMI LA CUI ANALISI NEL LORO HABITAT NATURALE VIENE DEFINITA METAGENOMA. LA METAGENOMICA HA MESSO IN EVIDENZA UNA DIVERSITA' SENZA PRECEDENTI NELLA COMPOSIZIONE DELLE COMUNITA' MICROBICHE CON UNA LARGHISSIMA PROPORZIONE DI NUOVI GENI.

  9. THE HUMAN GUT HOSTS MORE THAN 100 TRILLION BACTERIA, WHICH TOGETHER MAKE UP THE GUT MICROBIOTA. THE GUT MICROBIOTA CO-EVOLVED WITH HUMANS TO ACHIEVE A SYMBIOTIC RELATIONSHIP LEADING TO PHYSIOLOGICAL HOMEOSTASIS. THE HUMAN MICROBIOTA REMAINS GLOBALLY STABLE OVER TIME IN HEALTHY CONDITIONS AND ABSENCE OF PERTURBATION. APPLICATION OF METAGENOMICS TO THIS THIS ENVIRONMENT MAY HELP IN DECIPHERING KEY FUNCTIONS AND KEY BACTERIA INVOLVED IN HEALTH AND DISEASE.

  10. FAECAL BACTERIOTHERAPY: AN UNTHINKABLE APPROACH Faecal bacteriotherapy has a longstanding history in animal health. In human beings it has been used in selected cases, especially as a treatment of last resort for patients with severe Clostridium difficile pseudomembranous colitis. Schwan A, Sjölin S, Trottestam U, Aronsson B. Relapsing clostridium difficile enterocolitis cured by rectal infusion of homologous faeces. Lancet. 1983 Oct 8;2(8354):845. Borody TJ, Warren EF, Leis SM, Surace R, Ashman O, Siarakas S. Bacteriotherapy using fecal flora: toying with human motions. J Clin Gastroenterol. 2004 Jul;38 Although it is unthinkable that this approach will gain the favour of the people, it could indicate that the rectal infusion represents an alternative physiological administration way of probiotics in selected clinical conditions. Ricci N, Caselli M. Rectal infusion of bacterial preparations for intestinal disorders. Lancet 1983; ii:1984-85

  11. IN THE ERA OF METAGENOMICS FECAL TRANSPLANT AND SYNTHETIC MICROBIOME TRANSPLANT MIGHT BE VERY PROMISING THERAPIES FOR DYSBIOSIS-ASSOCIATED DISEASES.

  12. FUTURE OF MICROBIOME STUDIES NEED FOR STANDARDIZATION NEED FOR LARGE PROSPECTIVE COHORTS NEED FOR HOLISTIC APPROACH NEED FOR AN ECOLOGICAL UNDERSTANDING

  13. UNDERSTANDING CO-EVOLUTION OF THE MICROBIAL GENOMES AND HOST GENOME, FROM GEOGRAPHICALLY AND CULTURALLY DIVERSE POPULATIONS, WILL BE KEY FOR FUTURE STRATEGIC PREVENTIVE MEASURES THROUGHOUT THE LIFE-SPAN.

  14. METABOLOMIC VIEW METABOLOMIC APPROACHES, IN WHICH A LARGE NUMBER OF SMALL MOLECULE METABOLITES CAN BE DEFINED IN A BIOLOGICAL SAMPLE, OFFER A VERY PROMISING AND POWERFUL AVENUE TO “FINGERPRINT” MICROBIOTA FUNCTIONAL STATUS, WITH FUNCTIONAL CHARACTERIZATION OF THE INTESTINAL MICROBIOTA AND ITS INTERACTIONS WITH THE HOST.

  15. WHAT IS MORE IMPORTANT IN INDUCING INFLAMMATORY AND CANCEROUS CHANGES? - A GENERAL DESTRUCTURATION OF THE ECOSYSTEM - SOME SPECIFIC BACTERIA

  16. EXAMPLES OF EMERGIG SPECIFIC BACTERIA: -ENTEROTOXIGENIC BACTERIOIDES FRAGILIS INVOLVED IN IBD AND COLORECTAL CANCER -FUSOBACTERIA (NUCLEATUM, VARIUM, etc) INVOLVED IN IBD AND COLORECTAL CANCER -SEGMENTED FILAMENTOUS BACTERIA (SFB) POSSIBLY INVOLVED IN AUTOIMMUNE DISEASES

  17. PER CONOSCERE BENE LE COSE, BISOGNA CONOSCERNE I PARTICOLARI; E SICCOME QUESTI SONO INFINITI, LE NOSTRE CONOSCENZE SONO SEMPRE SUPERFICIALI ED IMPERFETTE. Francois de La Rochefoucauld, 1665

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