New potential biomarkers of ulcerative colitis and disease course - integrated metagenomic and metabolomic analysis among Polish patients.

Background & aim: The course of ulcerative colitis (UC) involves successive periods of remission and exacerbation but is difficult to predict. Gut dysbiosis in UC has already been intensively investigated. However, are periods of exacerbation and remission associated with specific disturbances in the composition of the intestinal microbiota and its metabolome? Our goal was to answer this question and to identify bacteria and metabolites necessary to maintain the remission.

Methods: We enrolled 65 individuals, including 20 UC patients in remission, 15 in exacerbation, and 30 healthy controls. Metagenomic profiling of the gut microbial composition was performed based on 16S rRNA V1-V9 sequencing. Stool and serum metabolic profiles were studied by chromatography combined with mass spectrometry.

Results: We revealed significant differences in the gut bacterial and metabolic composition between patients in active UC and those in remission, as well as in healthy controls. As associated with UC remission we have identified following bacteria: Akkermansia, Agathobacter, Anaerostipes, Enterorhabdus, Coprostanoligenes, Colinsella, Ruminococcus, Subdoligranulum, Lachnoclostridium, Coriobacteriales, Erysipelotrichaceae, and Family XII, and compounds - 1-hexadecanol, phytanic acid, squalene, adipic acid, cis-gondoic acid, nicotinic acid, tocopherol gamma, ergosterol and lithocholic acid. Whereas, in the serum lithocholic acid, indole and xanthine were found as potential candidates for biomarkers of UC remission.

Conclusion: We have demonstrated that specific bacteria, metabolites, and their correlations could be crucial in the remission of UC among Polish patients. Our results provide valuable insights and a significant source for developing new hypotheses on host-microbiome interactions in diagnosis and course of UC.