Liver Bacterial Colonization in Patients with Obesity and Gut Dysbiosis

Recently, the link between gut microbiota, liver inflammation, and obesity has become an interesting focus of research. The aim of this study is to show the possible relation between gut microbiota dysbiosis in patients with obesity and the presence of bacterial genomes in their liver biopsies.

A prospective study on patients undergoing bariatric surgery was carried out. Anthropometric and metabolic data, comorbidities, stool samples, and hepatic biopsies were collected and analyzed at the time of surgery. The V3-16S rRNA region was sequenced using the Ion Torrent new-generation sequencing platform.

In each of the 23 patients enrolled, the bacterial population was analyzed both in the stools and liver. In eight patients (34.7%), Prevotella (62.5%), Bacteroides (50%), Streptococcus (12.5%), and Dalister (12.5%) were found in both samples, simultaneously; in 15 cases, the liver was free from colonization. The statistically significant difference between groups was a Roseburia intestinalis reduction in fecal samples of patients with liver biopsies colonized by bacteria (1% vs 3%; p = 0.0339).

To the best of our knowledge, this is the first study reporting the presence of bacterial genome in a liver biopsy on bariatric patients, instead of the microbe-associated molecular patterns. Notably, in literature, the presence of Roseburia intestinalis in stool samples has been shown to prevent intestinal inflammation playing its role in the gut barrier integrity. In our population, the Roseburia reduction was associated with the presence of bacterial genome in the liver, probably related to a greater permeability of the gut and vascular barriers.