Pre-Crohn’s Microbiome Can Promote Colitis Years Before Disease Onset: Gastroenterology | September 2026

Introduction:

Microbiome abnormalities have been identified before Crohn’s disease (CD) develops, but association does not prove biological relevance. This study asked a powerful question: can stool collected from healthy individuals years before they develop Crohn’s actually promote intestinal inflammation?

Why was this study needed?

Most microbiome studies examine patients after CD has developed.

Dysbiosis could therefore be a consequence rather than a cause of inflammation.

Discordant siblings provide valuable control for shared genetics and environment.

Functional experiments are needed to move microbiome research beyond association.

Key Findings:

Germ-free mice received stool from 12 sibling pairs: one later developed CD and the other remained healthy.

Mice receiving pre-CD stool developed significantly more severe colitis after T-cell transfer.

They showed greater weight loss, fecal lipocalin-2, and histologic intestinal injury.

Metabolomics identified 40 metabolites differing between pre-CD and control-colonized mice.

Two metabolic pathways were conserved between human donors and recipient mice.

Sphingolipid metabolism was particularly notable and correlated with greater intestinal inflammation.

The findings suggest that microbiome alterations exist years before clinical Crohn’s disease and possess functional pro-inflammatory potential.

The human sample size was small, so these findings require broader validation.

Bottom Line:

The pre-Crohn’s microbiome may be more than a biomarker—it can transfer increased inflammatory potential to susceptible mice. This strengthens the possibility that microbiome changes participate in Crohn’s pathogenesis before clinical disease appears.