Distinct gut microbiomes in Thai patients with colorectal polyps

Area of Science:

• Microbiome research
• Gastrointestinal oncology
• Molecular biology

Background:

• Colorectal polyps, including tubular adenomas (TA) and hyperplastic polyps (HP), are linked to gut microbiome alterations.
• Understanding the microbiome's role in the serrated polyp pathway (HP) is limited compared to the conventional adenoma-carcinoma sequence (TA).
• Investigating HP and TA-associated microbiome changes can elucidate mechanisms in colorectal carcinogenesis.

Purpose of the Study:

• To investigate gut microbiome signatures, microbial associations, and microbial functions in patients with hyperplastic polyps (HP) and traditional adenomas (TA).

Main Methods:

• 16S rRNA sequencing was used to analyze stool samples from 40 controls, 52 HP patients, and 60 TA patients.
• Differential abundance, co-occurrence network, and differential pathway analyses were employed.
• Microbiome composition and functional mechanisms were compared between groups.

Main Results:

• TA patients showed CRC-associated bacteria (e.g., *Streptococcus gallolyticus*) and pathways in secondary metabolite biosynthesis.
• HP patients exhibited enrichment in the sulfur oxidation pathway.
• *Mediterraneibacter gnavus* was differentially abundant in both HP and TA groups.
• HP patients had co-occurrence of dysbiosis-associated bacteria, while TA patients had CRC-associated bacteria; SCFA-producing bacteria were less common in TA patients.

Conclusions:

• Distinct gut microbiome signatures are associated with different colorectal polyp pathways (HP vs. TA).
• Specific microbial species, functional pathways, and their interactions play roles in colorectal carcinogenesis.
• Findings provide insights into the mechanisms underlying colorectal polyp development via distinct pathways.