Enterobacter ludwigii protects DSS-induced colitis through choline-mediated immune tolerance

Area of Science:

• Microbiology
• Immunology
• Gastroenterology

Background:

• Commensal intestinal bacteria are crucial for immune tolerance, but specific strains and metabolites remain unidentified.
• Understanding these interactions is key to developing treatments for inflammatory bowel diseases (IBDs).

Purpose of the Study:

• To identify specific commensal bacteria and their metabolites that regulate host immune tolerance.
• To investigate the therapeutic potential of identified bacteria and metabolites in dextran sulfate sodium (DSS)-induced colitis.

Main Methods:

• Utilized a mouse model of DSS-induced colitis with antibiotic treatments.
• Screened for bacterial strains with prophylactic and therapeutic effects.
• Conducted in vitro and in vivo experiments to elucidate mechanisms involving dendritic cells (DCs) and regulatory T cells (Tregs).
• Identified bacterial metabolites and their signaling pathways (e.g., choline, α7nAChR, retinoic acid, TGF-β).

Main Results:

• Enterobacter ludwigii was identified as a beneficial bacterium with prophylactic and therapeutic effects on DSS-induced colitis.
• E. ludwigii induces immune tolerance via CD103+ dendritic cells (DCs) and regulatory T cells (Tregs).
• The metabolite choline from E. ludwigii enhances DC immune tolerance, promoting Treg differentiation through the α7nAChR pathway, upregulating retinoic acid (RA) and transforming growth factor beta (TGF-β).

Conclusions:

• Enterobacter ludwigii and its metabolite choline demonstrate therapeutic potential for colitis.
• The mechanism involves enhancing DC immune tolerance and Treg differentiation, offering new avenues for IBD treatment.