Gut microbiome structure and function in asymptomatic diverticulosis.

Background: Colonic diverticulosis, the most common lesion found in routine colonoscopy, affects more than 50% of individuals aged ≥ 60 years. Emerging evidence suggest that dysbiosis of gut microbiota may play an important role in the pathophysiology of diverticular disease. However, specific changes in microbial species and metabolic functions in asymptomatic diverticulosis remain unknown.

Methods: In a cohort of US adults undergoing screening colonoscopy, we analyzed the gut microbiota using shotgun metagenomic sequencing. Demographic factors, lifestyle, and medication use were assessed using a baseline questionnaire administered prior to colonoscopy. Taxonomic structures and metabolic pathway abundances were determined using MetaPhlAn3 and HUMAnN3. We used multivariate association with linear models to identify microbial species and metabolic pathways that were significantly different between asymptomatic diverticulosis and controls, while adjusting for confounders selected a priori including age at colonoscopy, sex, body mass index (BMI), and dietary pattern.

Results: Among 684 individuals undergoing a screening colonoscopy, 284 (42%) had diverticulosis. Gut microbiome composition explained 1.9% variation in the disease status of asymptomatic diverticulosis. We observed no significant differences in the overall diversity of gut microbiome between asymptomatic diverticulosis and controls. However, microbial species Bifidobacterium pseudocatenulatum and Prevotella copri were significantly enriched in controls (q value = 0.19 and 0.14, respectively), whereas Roseburia intestinalis, Dorea sp. CAG:317, and Clostridium sp. CAG: 299 were more abundant in those with diverticulosis (q values = 0.17, 0.24, and 0.10, respectively). We observed that the relationship between BMI and diverticulosis appeared to be limited to carriers of Bifidobacterium pseudocatenulatum and Roseburia intestinalis (P_interaction = 0.09).

Conclusions: Our study provides the first large-scale evidence supporting taxonomic and functional shifts of the gut microbiome in individuals with asymptomatic diverticulosis. The suggestive interaction between gut microbiota and BMI on prevalent diverticulosis deserves future investigations.