Anthocyanin-rich extract mitigates the contribution of the pathobiont genus Haemophilus in mild-to-moderate ulcerative colitis patients

ObjectiveAnthocyanins (AC) have been shown to elicit anti-inflammatory and antioxidant effects in several animal models of colitis. Furthermore, AC lowered biochemical disease activity in our double-blind randomized trial in patients with ulcerative colitis. Here, we report on the changes in the faecal microbiome composition in the patient upon AC exposure in this trial. MethodsUlcerative colitis patients received a 3g daily dose of an AC-rich bilberry extract (ACRE) for eight weeks. We determined the microbiome composition in longitudinal stool samples from 24 patients and quantified the degree of change over time. We also correlated the relative abundances of individual microbial taxa at different time points to faecal concentration measurements of calprotectin. ResultsMicrobiome compositions did not change over time as a result of the intervention, both in terms of alpha and beta diversity. Before the intervention, Haemophilus parainfluenzae was positively correlated with faecal calprotectin concentrations, and this correlation persisted in placebo-treated subjects throughout the study. In contrast, the correlation between H. parainfluenzae and the concentration of faecal calprotectin vanished in ACRE-treated subjects, while the relative abundance of H. parainfluenzaae did not change. Conclusion: Our results suggest that ACRE treatment mitigates the contribution of H. parainfluenzae to inflammation. Further research is warranted to better comprehend the role of microbial composition in response to medical therapy including AC-rich extract in ulcerative colitis patients. Key messagesO_ST_ABS1. What is already known on this topicC_ST_ABSAnthocyanins are a promising therapeutic alternative for ulcerative colitis patients given their effect on faecal calprotectin, excellent safety profile, and low costs. 2. What this study addsThe administration of anthocyanin-rich extract to ulcerative colitis patients in a Phase 2a study reduced faecal calprotectin concentrations by mitigating the contribution from the pathobiont genus Haemophilus but did not affect the overall microbiome composition. 3. How this study might affect research, practice or policyOur results could aid in targeted treatment of ulcerative colitis patients with anthocyanins, according to individual microbial composition.