title: Microbial dysbiosis in colorectal cancer (CRC) patients.
abstract: The composition of the human intestinal microbiota is linked to health status. The aim was to analyze the microbiota of normal and colon cancer patients in order to establish cancer-related dysbiosis.
  
  
  METHODS
  Stool bacterial DNA was extracted prior to colonoscopy from 179 patients: 60 with colorectal cancer, and 119 with normal colonoscopy. Bacterial genes obtained by pyrosequencing of 12 stool samples (6 Normal and 6 Cancer) were subjected to a validated Principal Component Analysis (PCA) test. The dominant and subdominant bacterial population (C. leptum, C. coccoides, Bacteroides/Prevotella, Lactobacillus/Leuconostoc/Pediococcus groups, Bifidobacterium genus, and E. coli, and Faecalibacterium prausnitzii species) were quantified in all individuals using qPCR and specific IL17 producer cells in the intestinal mucosa were characterized using immunohistochemistry.
  
  
  RESULTS
  Pyrosequencing (Minimal sequence 200 nucleotide reads) revealed 80% of all sequences could be assigned to a total of 819 taxa based on default parameter of Classifier software. The phylogenetic core in Cancer individuals was different from that in Normal individuals according to the PCA analysis, with trends towards differences in the dominant and subdominant families of bacteria. Consequently, All-bacteria [log(10) (bacteria/g of stool)] in Normal, and Cancer individuals were similar [11.88±0.35, and 11.80±0.56, respectively, (P = 0.16)], according to qPCR values whereas among all dominant and subdominant species only those of Bacteroides/Prevotella were higher (All bacteria-specific bacterium; P = 0.009) in Cancer (-1.04±0.55) than in Normal (-1.40±0.83) individuals. IL17 immunoreactive cells were significantly expressed more in the normal mucosa of cancer patients than in those with normal colonoscopy.
  
  
  CONCLUSIONS
  This is the first large series to demonstrate a composition change in the microbiota of colon cancer patients with possible impact on mucosal immune response. These data open new filed for mass screening and pathophysiology investigations.
authors.affiliation: Department of Gastroenterology and LIC-EA4393, APHP and UPEC Université Paris-Est Créteil, Créteil, France. iradj.sobhani@hmn.aphp.fr
authors.forename: Iradj
authors.initials: I
authors.lastname: Sobhani
authors.forename: Julien
authors.initials: J
authors.lastname: Tap
authors.forename: Françoise
authors.initials: F
authors.lastname: Roudot-Thoraval
authors.forename: Jean P
authors.initials: JP
authors.lastname: Roperch
authors.forename: Sophie
authors.initials: S
authors.lastname: Letulle
authors.forename: Philippe
authors.initials: P
authors.lastname: Langella
authors.forename: Gérard
authors.initials: G
authors.lastname: Corthier
authors.forename: Jeanne
authors.initials: J
authors.lastname: Tran Van Nhieu
authors.forename: Jean P
authors.initials: JP
authors.lastname: Furet
mesh_terms: D001419:Bacteria / Q000302:isolation & purification; D001439:Bacteroides; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000382:microbiology*; D004269:DNA, Bacterial / Q000032:analysis; D005243:Feces / Q000382:microbiology; D006801:Humans; D020381:Interleukin-17; D007413:Intestinal Mucosa / Q000473:pathology; D007422:Intestines / Q000382:microbiology*; D054892:Metagenome; D018720:Prevotella; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial; D020381:Interleukin-17