The Salivary Microbiome and Predicted Metabolite Production Are Associated with Barrett's Esophagus and High-Grade Dysplasia or Adenocarcinoma

BACKGROUND

Esophageal adenocarcinoma (EAC) is rising in incidence, and established risk factors do not explain this trend. Esophageal microbiome alterations have been associated with Barrett's esophagus (BE) and dysplasia and EAC. The oral microbiome is tightly linked to the esophageal microbiome; this study aimed to identify salivary microbiome-related factors associated with BE, dysplasia, and EAC.

METHODS

Clinical data and oral health history were collected from patients with and without BE. The salivary microbiome was characterized, assessing differential relative abundance of taxa by 16S rRNA gene sequencing and associations between microbiome composition and clinical features. Microbiome metabolic modeling was used to predict metabolite production.

RESULTS

A total of 244 patients (125 non-BE and 119 BE) were analyzed. Patients with high-grade dysplasia (HGD)/EAC had a significantly higher prevalence of tooth loss (P = 0.001). There were significant shifts with increased dysbiosis associated with HGD/EAC, independent of tooth loss, with the largest shifts within the genus Streptococcus. Modeling predicted significant shifts in the microbiome metabolic capacities, including increases in L-lactic acid and decreases in butyric acid and L-tryptophan production in HGD/EAC.

CONCLUSIONS

Marked dysbiosis in the salivary microbiome is associated with HGD and EAC, with notable increases within the genus Streptococcus and accompanying changes in predicted metabolite production. Further work is warranted to identify the biological significance of these alterations and to validate metabolic shifts.

IMPACT

There is an association between oral dysbiosis and HGD/EAC. Further work is needed to establish the diagnostic, predictive, and causal potential of this relationship.

The Salivary Microbiome and Predicted Metabolite Production are Associated with Progression from Barrett's Esophagus to Esophageal Adenocarcinoma

Esophageal adenocarcinoma (EAC) is rising in incidence and associated with poor survival, and established risk factors do not explain this trend. Microbiome alterations have been associated with progression from the precursor Barrett's esophagus (BE) to EAC, yet the oral microbiome, tightly linked to the esophageal microbiome and easier to sample, has not been extensively studied in this context. We aimed to assess the relationship between the salivary microbiome and neoplastic progression in BE to identify microbiome-related factors that may drive EAC development. We collected clinical data and oral health and hygiene history and characterized the salivary microbiome from 250 patients with and without BE, including 78 with advanced neoplasia (high grade dysplasia or early adenocarcinoma). We assessed differential relative abundance of taxa by 16S rRNA gene sequencing and associations between microbiome composition and clinical features and used microbiome metabolic modeling to predict metabolite production. We found significant shifts and increased dysbiosis associated with progression to advanced neoplasia, with these associations occurring independent of tooth loss, and the largest shifts were with the genus Streptococcus. Microbiome metabolic models predicted significant shifts in the metabolic capacities of the salivary microbiome in patients with advanced neoplasia, including increases in L-lactic acid and decreases in butyric acid and L-tryptophan production. Our results suggest both a mechanistic and predictive role for the oral microbiome in esophageal adenocarcinoma. Further work is warranted to identify the biological significance of these alterations, to validate metabolic shifts, and to determine whether they represent viable therapeutic targets for prevention of progression in BE.

Minimal Associations between Short-Term Dietary Intake and Salivary Microbiome Composition

Background: Increasing evidence points to the esophageal microbiome as an important co-factor in esophageal neoplasia. Esophageal microbiome composition is strongly influenced by the oral microbiome. Salivary microbiome assessment has emerged as a potential non-invasive tool to identify patients at risk for esophageal cancer, but key host and environmental factors that may affect the salivary microbiome have not been well-defined. This study aimed to evaluate the impact of short-term dietary intake on salivary microbiome composition. Methods: Saliva samples were collected from 69 subjects prior to upper endoscopy who completed the Automated Self-Administered 24-Hour (ASA24) Dietary Assessment. Salivary microbiome composition was determined using 16S rRNA amplicon sequencing. Results: There was no significant correlation between alpha diversity and primary measures of short-term dietary intake (total daily calories, fat, fiber, fruit/vegetables, red meat intake, and fasting time). There was no evidence of clustering on beta diversity analyses. Very few taxonomic alterations were found for short-term dietary intake; an increased relative abundance of Neisseria oralis and Lautropia sp. was associated with high fruit and vegetable intake, and an increased relative abundance of a taxon in the family Gemellaceae was associated with increased red meat intake. Conclusions: Short-term dietary intake was associated with only minimal salivary microbiome alterations and does not appear to have a major impact on the potential use of the salivary microbiome as a biomarker for esophageal neoplasia.

Clinical significance of recurrent gastroesophageal junction intestinal metaplasia after endoscopic eradication of Barrett's esophagus

BACKGROUND AND AIMS

After endoscopic eradication of Barrett's esophagus (BE), recurrence of intestinal metaplasia at the gastroesophageal junction (GEJIM) is common. The clinical significance of this finding is unclear. We assessed whether recurrent GEJIM is associated with increased risk of subsequent dysplasia and whether endoscopic treatment lowers this risk.

METHODS

A retrospective, multicenter, cohort study was performed of treated BE patients who achieved complete eradication of intestinal metaplasia (IM). Postablation follow-up was performed at standard intervals. Recurrent GEJIM was defined as nondysplastic IM on gastroesophageal junction biopsy specimens without endoscopic evidence of BE. Patients were categorized as "never-GEJIM," "GEJIM-observed," or "GEJIM-treated." Endoscopic treatment for recurrent GEJIM was at the endoscopists' discretion. The primary outcome was dysplasia recurrence. Analyses were performed using log-rank tests and Cox proportional hazards modeling.

RESULTS

Six hundred thirty-three patients were analyzed; median follow-up was 47 months (interquartile range, 24-69). Most patients (81%) had high-grade dysplasia or intramucosal adenocarcinoma before treatment. Dysplasia recurrence was 2.2% per year. GEJIM-observed patients had the lowest rate of recurrence (.6%/y) followed by GEJIM-treated (2.2%/y) and never-GEJIM (2.6%/y) (log-rank P = .07). In multivariate analyses, compared with never-GEJIM, the risk of dysplasia recurrence was significantly lower in GEJIM-observed patients (adjusted hazard ratio, .19; 95% confidence interval, .05-.81) and not different in GEJIM-treated patients (adjusted hazard ratio, .81; 95% confidence interval, .39-1.67). Older age and longer initial BE length were independently associated with recurrence.

CONCLUSIONS

Recurrent GEJIM after endoscopic eradication of BE was not associated with an increased risk of subsequent dysplasia. Future studies are warranted to determine if observation is appropriate for this finding.