The pathophysiology of prostate enlargement is unknown. Meanwhile, the gut microbiota can contribute to various host conditions. We hypothesized that the gut microbiota plays a role in prostate enlargement. To confirm this hypothesis, we analyzed the relationship between the gut microbiota and prostate enlargement and analyzed whether the gut microbiota exhibited any characteristic trends associated with prostate enlargement.
We included 128 patients who underwent prostate biopsies between December 2018 and March 2020, excluding those who had used antibiotics within the past 6 months and those who were diagnosed with prostate cancer of cT3 or higher. Patients with prostate volumes ≥30 ml were defined as the prostate-enlargement (PE) group; those with prostate volumes <30 ml were defined as the non-PE group. Their gut microbiotas were analyzed via 16S rRNA metagenomic analyses of rectal swab samples and were compared between the groups.
The PE group included 66 patients; the non-PE group included 62 patients. Age, body mass index, and prostate specific antigen levels did not significantly differ between the groups. Linear discriminant analysis effect size analysis indicated a higher proportion of Firmicutes and Actinobacteria in the PE group and a higher proportion of Bacteroidetes in the non-PE group (Figure A). We addressed the Firmicutes/Bacteroidetes (F/B) ratio of the gut microbiota, which is reported to represent the condition of the gut microbiota and is associated with various diseases. The F/B ratio was significantly higher in the PE group than in the non-PE group (2.21 ± 0.39 vs. 1.61 ± 0.40, p = 0.015 by Mann-Whitney U test; Figure B).
The F/B ratio of the gut microbiota was associated with prostate enlargement, suggesting an association between the gut microbiota and prostate enlargement.