Inhibition of PD-1 Protects against TNBS-Induced Colitis via Alteration of Enteric Microbiota

Area of Science:

• Immunology
• Microbiome research
• Gastroenterology

Background:

• Inflammatory bowel disease (IBD) is a chronic condition affecting the gastrointestinal tract.
• The gut microbiome plays a crucial role in IBD pathogenesis and progression.
• Current treatments for IBD have limitations, necessitating novel therapeutic strategies.

Purpose of the Study:

• To investigate the therapeutic potential of PD-1 inhibition in a mouse model of colitis.
• To evaluate the impact of PD-1 inhibition on the enteric microbiota composition and function.

Main Methods:

• Colitis was induced in mice using 2,4,6-trinitrobenzene-sulfonic acid (TNBS).
• Mice were treated with a PD-1 inhibitor or 5-amino-salicylic acid (ASA).
• Disease activity, colon length, and enteric microbiota were assessed using 16S rRNA sequencing.

Main Results:

• PD-1 inhibition significantly attenuated TNBS-induced colitis symptoms, reducing disease activity index scores (p = 0.0002).
• PD-1 inhibition improved alpha diversity and restored beta diversity of the enteric microbiome.
• Treatment enriched SCFA-producing bacteria (Firmicutes, Bacteroidetes) and reduced Proteobacteria.

Conclusions:

• PD-1 inhibition demonstrates therapeutic efficacy in mitigating experimental colitis.
• PD-1 inhibition modulates the gut microbiome, promoting a healthier microbial environment.
• Restoration of SCFA-producing bacteria by PD-1 inhibition may contribute to its beneficial effects in IBD.