Altered Duodenal Mucosa‐Associated Microbiota and Immune Profiles in Functional Dyspepsia: A Study of Host‐Microbiome Homeostasis

BACKGROUND: Recent work suggests an altered duodenal mucosa-associated microbiota (d-MAM) in patients with functional dyspepsia (FD) when compared to controls. This may reflect alterations in host-microbiome homeostasis. Given the specific mucosal immune signatures identified in FD, we hypothesize that these signatures are associated with specific microbial changes. We aim to profile the d-MAM to identify microbes associated with known changes in FD mucosal and peripheral immunity. METHODS: Upper gastrointestinal biopsies were collected from 11 outpatient controls and 17 FD patients. Specific biopsies were collected for 16S rRNA sequencing, histology, and mucosal lamina propria mononuclear cell (LPMC) isolation. Where available, peripheral blood mononuclear cells (PBMC) were isolated. PBMC and LPMC populations were analyzed for T-cell populations by flow cytometry. KEY RESULTS: Comparing the histological and immune measures between FD and controls revealed significant differences with decreased villi goblet cells and increased LPMC CD4 Central Memory, LPMC CD8, and PBMC CD4+ Central Memory Th17 in FD patients. Specific microbiome associations found that in controls, villi goblet cells positively correlated with Massilia and negatively with Exiguobacterium. Additionally, controls had a negative correlation between LPMC CD4 Central Memory and Veillonella. Notably, FD patients demonstrated a significant negative correlation between LPMC CD8 and Sulfophobococcus, and a positive correlation between PBMC CD4+ Central Memory Th17 and both Gemella and Fusobacterium. CONCLUSIONS AND INFERENCES: Our findings contribute to a growing body of evidence, indicating FD patients exhibit distinct alterations in d-MAM and immune profiles compared to controls. Furthermore, the immune-microbiome associations within control populations were absent in FD patients, suggesting a loss of host-microbiome homeostasis that may contribute to FD pathophysiology.