LAUSR

BACKGROUND Gut microbiota dysbiosis is associated with the occurrence and development of Crohn disease (CD). Currently, infliximab (IFX) is used more and more to treat CD; however, gut microbiota alterations during IFX therapy are variable and sometimes even contradictory. We longitudinally identified microbial changes during IFX therapy associated with the clinical and endoscopic response to IFX treatment in CD. METHODS Fecal-associated microbiota was analyzed using 16S sequencing in 49 patients with active CD who were prospectively recruited at baseline, week 6, and week 30, respectively. Moreover, a model trained on the gut microbiota alterations at week 6 was developed to investigate their potential to predict clinical and endoscopic responses to IFX therapy at weeks 14 and 30. RESULTS Characteristics of fecal microbiota composition in patients with CD after IFX treatment displayed an increased diversity and richness, a significant gain in short-chain fatty acid -producing bacteria, and a loss of pathogenic bacteria. Furthermore, certain functional profiles of Kyoto Encyclopedia of Genes and Genomes pathways were predictably altered during the treatment period. Increased proportions of Lachnospiraceae and Blautia were associated with IFX efficacy; the combined increase of these taxa at week 6 showed 83.4% and 84.2% accuracy in predicting clinical response at weeks 14 and 30, respectively, with a predictive value of 89.1% in predicting endoscopic response at week 30. CONCLUSIONS We found that IFX diminished CD-related gut microbial dysbiosis by modifying microbiota composition and function. Specifically, increased Lachnospiraceae and Blautia at week 6 are associated with the clinical and endoscopic response to IFX, providing potentially predictive biomarkers for IFX treatment decision-making.