Mitochondrial perturbation in the intestine causes microbiota-dependent injury and gene signatures discriminative of inflammatory disease.

Mitochondrial dysfunction is associated with inflammatory bowel diseases (IBDs). To understand how microbial-metabolic circuits contribute to intestinal injury, we disrupt mitochondrial function in the epithelium by deleting the mitochondrial chaperone, heat shock protein 60 (Hsp60Δ/ΔIEC). This metabolic perturbation causes self-resolving tissue injury. Regeneration is disrupted in the absence of the aryl hydrocarbon receptor (Hsp60Δ/ΔIEC;AhR-/-) involved in intestinal homeostasis or inflammatory regulator interleukin (IL)-10 (Hsp60Δ/ΔIEC;Il10-/-), causing IBD-like pathology. Injury is absent in the distal colon of germ-free (GF) Hsp60Δ/ΔIEC mice, highlighting bacterial control of metabolic injury. Colonizing GF Hsp60Δ/ΔIEC mice with the synthetic community OMM12 reveals expansion of metabolically flexible Bacteroides, and B. caecimuris mono-colonization recapitulates the injury. Transcriptional profiling of the metabolically impaired epithelium reveals gene signatures involved in oxidative stress (Ido1, Nos2, Duox2). These signatures are observed in samples from Crohn's disease patients, distinguishing active from inactive inflammation. Thus, mitochondrial perturbation of the epithelium causes microbiota-dependent injury with discriminative inflammatory gene profiles relevant for IBD.

Microbiota metabolized Bile Acids accelerate Gastroesophageal Adenocarcinoma via FXR inhibition.

Background: The incidence of Barrett esophagus (BE) and Gastroesophageal Adenocarcinoma (GEAC) correlates with obesity and a diet rich in fat. Bile acids (BA) support fat digestion and undergo microbial metabolization in the gut. The farnesoid X receptor (FXR) is an important modulator of the BA homeostasis. The capacity of inhibiting cancer-related processes when activated, make FXR an appealing therapeutic target. In this work, we assess the role of diet on the microbiota-BA axis and evaluate the role of FXR in disease progression. Results: Here we show that high fat diet (HFD) accelerated tumorigenesis in L2-IL1B mice (BE- and GEAC- mouse model) while increasing BA levels and enriching gut microbiota that convert primary to secondary BA. While upregulated in BE, expression of FXR was downregulated in GEAC in mice and humans. In L2-IL1B mice, FXR knockout enhanced the dysplastic phenotype and increased Lgr5 progenitor cell numbers. Treatment of murine organoids and L2-IL1B mice with the FXR agonist obeticholic acid (OCA) deacelerated GEAC progression. Conclusion: We provide a novel concept of GEAC carcinogenesis being accelerated via the diet-microbiome-metabolome axis and FXR inhibition on progenitor cells. Further, FXR activation protected with OCA ameliorated the phenotype in vitro and in vivo, suggesting that FXR agonists have potential as differentiation therapy in GEAC prevention.

Analysis of Fecal, Salivary, and Tissue Microbiome in Barrett's Esophagus, Dysplasia, and Esophageal Adenocarcinoma.

Background and Aims: Esophageal adenocarcinoma (EAC) incidence has risen dramatically in the Western countries over the past decades. The underlying reasons are incompletely understood, and shifts in the esophageal microbiome have been postulated to increase predisposition to disease development. Multiple factors including medications, lifestyle, and diet could influence microbiome composition and disease progression. The aim of this study was (1) to identify a feasible method to characterize the tissue-associated microbiome, and (2) to investigate differences in the microbiome of saliva, esophageal tissue, and fecal samples by disease state and validate with 2 external cohorts. Methods: Forty-eight patients (15 Barrett's esophagus [BE], 4 dysplasia, 15 EAC, and 14 healthy) were enrolled in this cross-sectional study (Munich cohort). Demographics, epidemiologic and clinical data, medications, smoking, and alcohol consumption were assessed. 16S rRNA Gene sequencing was performed on saliva, tissue biopsy and fecal samples. PAXgene fixation was used as a novel methodology. Microbial community alpha- and beta-diversity, as well as microbial composition at phylum and genus level, were characterized for this cohort and compared with 2 external cohorts: New York cohort and Cooperative Health Research in the Augsburg Region cohort. Results: We first established PAXgene fixation is a feasible method for microbiome analysis and utilized it to identify a distinct microbial shift in tissue biopsies from patients with EAC, whereas overall microbial diversity in salivary and fecal samples did not differ significantly between disease states. Our findings were similar in a reanalysis to those from a US cohort that used a standardized fresh frozen biopsy collection protocol (New York cohort, N = 75 biopsies). Nevertheless, we could not distinguish German Munich cohort patients from a German population-based cohort (Cooperative Health Research in the Augsburg Region cohort, N = 2140 individuals) when fecal bacterial profiles were compared between both cohorts. In addition, we used data integration of diagnosis and risk factors of patients and found associations with microbiome alterations. Conclusion: Sample collection and microbiome analysis are indeed feasible and can be implemented into clinical routine by an easy-to-use biopsy protocol. The presence of BE and EAC together with epidemiologic factors can be associated with alterations of the salivary, tissue, and fecal microbial community in an easy-to-use data integration concept. Given a possible role of the microbiome in BE and EAC, it will be important in future studies to take tissue-specific microbial communities and individual taxa into account in larger prospective studies.