Preliminary data on oral and fecal microbiota in patients affected by Lynch Syndrome

Raffaella Alessia Zuppardo1, Roberto Ferrarese2, Alessandro Mannucci1, Graziana Antoci1, Ilaria Ditonno1, Chiara Notaristefano1, Mariagrazia Patricelli3, Annalisa Russo Raucci3, Milena Di Leo4, Pier Alberto Testoni1, Nicasio Mancini2, Giulia Martina Cavestro1

1Gastroenterology and Gastrointestinal Endoscopy, Division of Experimental Oncology, Vita-Salute San Raffaele University, IRCCS Ospedale San Raffaele Scientific Institute, Milan, Italy. 2Microbiology and Virology Unit, IRCCS Ospedale San Raffaele, Università Vita-Salute San Raffaele, , Milan, Italy. 3Division of Genetics and Cell Biology, Unit of Genomics for Human Disease Diagnosis, IRCCS Ospedale San Raffaele Scientific Institute, Milan, Italy. 4Digestive Endoscopy Unit, Division of Gastroenterology, Humanitas Clinical and Research Center, Department of Biomedical Sciences, Humanitas University, Milan, Italy


Objective Microbiota seems to be involved in colorectal cancer(CRC)pathogenesis. We characterised oral and fecal microbiota in Lynch syndrome(LS) patients compared with healthy normal controls.

Methods We analysed oral and fecal microbiota of 17LS patients’: 12MSH2 mutation carriers, 3MLH1, 2MSH6. 11 patients were affected by CRC,1gastric,1endometrial and 1duodenal cancer. As control group we analysed 41 matched healthy normal controls. The V3-V4 region of the 16s rRNA gene was amplified. Purified DNA was quantified and libraries were diluted and mixed for pooling with unique molecular tags. Sequences with high quality score and length > 250bp used for taxonomic analysis with QIIME software.

Results Alpha diversity was statistically different between the 2 groups, with a lower observed otus/chao1 index in LS compared to controls.Unweighted beta diversity distinguished the two populations. At the genus level, oral wash samples taxonomic analysis showed a statistically significant increase of Veillonella(17% vs 11%)and a decrease of Neisseria (10% vs 17%)and Prevotella(3% vs 5%) in LS patients compared to controls. Between the 2 groups no statistically significant differences were observed in fecal microbiota for alpha diversity, nor in beta diversity. Fecal samples taxonomic analysis identified a statistically significant increase of Bifidobacteriaceae in LS compared to controls(2% vs 0%)and a slight increase of Enterobacteriaceae in LS samples (1% vs 0%).

Conclusion Increased Veillonella and decreased Neisseria were observed in oral wash samples of LS patients, and Bifidobacteriaceae were increased in LS fecal samples, previously described in sporadic CRC. Larger studies are needed to confirm or revoke these results.