CHARACTERIZATION OF ESOPHAGEAL MICROBIOTA IN PATIENTS WITH BARRETT'S ESOPHAGUS AND ESOPHAGEAL ADENOCARCINOMA

Aims:

The aim of our study was to characterize esophageal microbiota composition in patients with BE and EAC.

Methods:

26 patients were enrolled: 10 healthy patients as control group; 10 with a diagnosis of BE and 6 with a new diagnosis of EAC. Genomic DNA was extracted from distal esophagus biopsies and V3-V4 regions of the 16S rRNA gene were sequenced by MiSeq Illumina platform. In patients with BE, biopsies were obtained from both metaplasic (BEM) and normal mucosa (BEU).

Results:

BE and EAC patients showed an overall higher level of biodiversity which was statistically significant between BE and control patients (Wilcoxon test for Phylogenetic Diversity Whole Tree metric p < 0.05). When evaluating β-diversity, a separation on the first axis was observed for unweighted Unifrac, in which control samples were significantly separated from both BE (p < 0.005) and EAC (p < 0.05), as well as BE were substantially diverging from EAC (p < 0.05). BEU samples showed significant higher values of α-diversity (PD whole tree) when compared with control patients (p < 0.05), while BEM shared similar values with EAC, being lower than BEU and higher than control patients. A substantial divergence on the first axis was registered for unweighted Unifrac with control patients significantly separated from BEU (p < 0.005) and EAC samples (p < 0.05). Among phyla, relative abundance analysis revealed a lower level of Firmicutes and a significantly higher percentage of Bacteroidetes in BEU and EAC compared with control subjects. BEU and BEM exhibited a significantly higher presence of Fusobacteria compared with control samples. At genus level, Streptococcus relative abundance showed a reduction in EAC when compared with BEM and control samples.

Conclusions:

These data describe a specific microbial signature for both BE and EAC and open new horizons towards the identification of potential risk factors for the progression.