Local Interactions Between Innate Immune Signaling, Microbiota, and Bile Acids Drive the Development of Duodenal...

Area of Science:

• Gastroenterology
• Oncology
• Immunology

Background:

• Duodenal adenomas possess malignant potential, but their underlying drivers are not fully understood.
• Transgenic mice with enhanced intestinal epithelial Toll-like receptor 4 (TLR4) signaling spontaneously develop duodenal adenomas.

Purpose of the Study:

• To investigate the roles of the gut microbiota and bile acids in duodenal adenoma formation.
• To explore the mechanisms of myeloid cell recruitment and their contribution to duodenal tumorigenesis.

Main Methods:

• Analysis of duodenal tissue proliferation and histology in villin-TLR4 and wild-type mice.
• Germ-free rederivation, cholestyramine diet, and apocynin treatment in mice.
• Measurement of chemokine expression, myeloid cell recruitment, and corroboration with human duodenal adenoma data via RNA sequencing and tissue microarrays.

Main Results:

• Epithelial TLR4 activation induced duodenal adenomas with an intestinal phenotype.
• Germ-free conditions or cholestyramine administration prevented tumor initiation by reducing chemokine expression and myeloid cell recruitment.
• Human duodenal adenomas showed enriched neutrophil activation pathways, increased chemokines, and myeloid cell infiltration.

Conclusions:

• Bile acids and microbiota are essential for duodenal adenoma development, representing potentially modifiable risk factors.
• Myeloid cell recruitment, possibly via reactive oxygen species, may contribute to duodenal tumor progression.