Oral, intestinal, and pancreatic microbiomes are correlated and exhibit co-abundance in patients with pancreatic cancer and other gastrointestinal diseases

Oral microbiota are believed to play important roles in systemic diseases, including cancer. We collected oral swabs and at least one pancreatic tissue or intestinal samples from 52 subjects, and characterized 16S ribosomal RNA genes using high-throughput DNA sequencing in a total 324 samples. We identified a total of 73 unique Amplicon Sequence Variants (ASVs) that were shared between oral and pancreatic or intestinal samples. Accounting for pairing and within-subject correlation, 7 ASVs showed significant concordance (Kappa statistics) and 5 ASVs exhibited significant or marginally significant Pairwise Stratified Association (PASTA) between oral samples and pancreatic tissue or intestinal samples. Of these, two specific bacterial species (Gemella morbillorum and Fusobacterium nucleatum subsp. vincentii) showed consistent presence or absence patterns between oral and intestinal or pancreatic samples. Lastly, our microbial co-abundance analyses showed several distinct ASVs clusters and complex correlation-networks between ASV clusters in buccal, saliva, duodenum, jejunum, and pancreatic tumor samples. Toghether, our findings suggest that oral, intestinal, and pancreatic microbiomes are correlated and bacteria of oral origin exhibit co-abundance relationships and demonstrate complex correlation patterns in the intestinal and pancreatic tumor samples. Future prospective studies should aim to uncover the co-abundance of specific microbial communities for studying etiology of microbiota-driven carcinogenesis.