Characterization of the oral and intestinal microbiota in hepatocellular carcinoma

Abstract

Abstract Background Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. HCC has been found to be associated with oral and intestinal flora, and the aim of this paper is to characterize the composition and metabolism of oral and intestinal microbiota and investigate their functions in HCC. Methods Based on 16S rRNA gene sequencing and clinical data, this study concentrated on a cohort of 29 patients with hepatitis B virus-associated hepatocellular carcinoma (HBV-HCC) and a cohort of 20 patients with chronic viral hepatitis B (HBV). Strict inclusion and exclusion criteria were followed. Results Shannon and Simpson indices showed slightly lower oral and gut microbiota diversity and significantly higher OTUS (Chao1, ACE, OTUs, PD whole tree) in HCC patients. Linear discriminant analysis (LDA) effect size (LEfSe) revealed a substantial difference between the gut and oral microbiota of HCC patients and the control group. Further OTUs analysis of the oral microbiota showed a significant decrease in Proteobacteria and an impressive rise in Firmicutes and Bacteroidota abundance in the HCC, as well as a significant decrease in Firmicutes and a crucial increase in Proteobacteria and Bacteroidota abundance in the gut microbiota. The most significant groups in the oral and intestinal tracts at the genus level were Neisseria perflava and bacteroidales, respectively. According to the Venn chart, Firmicutes, Bacteroidota, and Proteobacteria represent a majority of the common flora found in the oral and intestinal tracts of HCC patients; Neisseria, Bacteroides, and Prevotella are more significant at the genus level. Finally, Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) found that a significant elevation of glycan metabolism occurred in the intestinal and oral flora. Conclusion The biodiversity of the oral and intestinal flora of HCC patients was significantly higher, characterized by Proteobacteria, Firmicutes, Bacteroidota, Fusobacteriota, and Actinobacteria. At the genus level, Neisseria perflava was the most important; Neisseria, Bacteroides, and Prevotella were symbiotic bacteria in two ecological niches; they all contribute to the progression of HCC through the oral-intestinal-hepatic axis. Glycan biosynthesis and metabolism are significantly more active in the oral and intestinal flora of patients with HCC, and may promote hepatocellular carcinoma growth.