FAECAL-ASSOCIATED AND MUCOSAL-ASSOCIATED MICROBIOTA IN INFLAMMATORY BOWEL DISEASE PATIENTS AND HEALTHY SUBJECTS: PRELIMINARY EVIDENCE

Background and aim: Over the last few years, growing evidencehas supported the potential role of intestinal microbiota in thepathophysiology and symptom generation of several gastrointestinal(GI) diseases, such as Inflammatory Bowel Disease (IBD). The existingliterature on the intestinal microbiota in IBD does not reveal uniformalterations in microbiota composition among all patients. Severalstudies have seen abnormal GI microbiotas; however, the relevanceof such studies has been hampered by the fact that the analyses werefocused only on the faecal microbiota, which differs substantiallyfrom that adhering to the gut mucosa. In the present study, weevaluated the microbiota composition in intestinal mucosal biopsiesand faecal samples of IBD patients and control subjects (CTRLs) in acase-control study exploited by 16S rRNA targeted metagenomicsbasedapproach (phylotyping, PH).Material and methods: Faecal specimens were collected from 12IBD patients and from 11 healthy subjects, undergone to colonoscopyfor screening. Colonic mucosal specimens were obtained duringcolonoscopy from the proximal descending colon. All patients filledout a standardized questionnaire for the GI symptoms and thequality of life. All the patients were enrolled only after signing theinformed consent. PH was assessed by pyrosequencing as follows.Genomic DNA was isolated from the entire set of samples using theQIAamp DNA Stool Mini Kit (Qiagen, Germany). The V1-V3 region of16S rRNA locus was amplified on a 454-Junior Genome Sequencer(Roche 454 Life Sciences, Branford, USA). Reads were analyzed byQuantitative Insights into Microbial Ecology (QIIME, v.1.8.0), groupedinto operational taxonomic units (OTUs) at a sequence similaritylevel of 97% by PyNAST for taxonomic assignment, and aligned byUCLUST for OTUs matching against Greengenes database (v. 13.8).Results: In adult IBD patients colonic biopsies showed a statisticallysignificant increase of Proteobacteria and decrease of Firmicutes,compared to CTRLs, with main OTUs in IBDs being Enterobacteriaceeand Clostridiales compared to Ruminococcacee, Prevotella,Bacteroides and Faecalibacterium praustinizii in CTRLs (p<0.05). Theanalysis of IBD faecal samples reproduced these data except for asignificant reduction of Clostridiales in IBD faecal samples, compareto CTRLs.Conclusions: Our data suggest the potential of microbiota profilingin the descritption of disease-related microbiota enterogradients.