Immunoregulatory effects of RGMb in gut inflammation

Area of Science:

• Immunology
• Gastroenterology
• Oncology

Background:

• Graft-versus-host disease (GvHD) and inflammatory bowel disease (IBD) are significant clinical challenges with current treatments causing considerable morbidity.
• Repulsive Guidance Molecule b (RGMb), a molecule involved in signaling pathways, is expressed in the gut and its expression increases after conditioning for allogeneic hematopoietic cell transplantation (HCT).

Purpose of the Study:

• To investigate the role of RGMb in the pathogenesis of GvHD and IBD.
• To evaluate the therapeutic potential of blocking RGMb in preclinical models of GvHD and IBD.

Main Methods:

• Utilized major-mismatched HCT mouse models to study GvHD and a dextran sulfate sodium model for IBD.
• Administered an anti-RGMb monoclonal antibody (mAb) designed to block interactions with BMP-2/4 and neogenin.
• Assessed GvHD and IBD severity, survival rates, graft-versus-tumor (GVT) effect, and cytokine profiles (IFN-γ, IL-5, IL-10).

Main Results:

• Treatment with anti-RGMb mAb significantly improved survival in GvHD models (75% vs. 30%) and IBD models (73% vs. 33%) compared to isotype control.
• The anti-RGMb mAb treatment preserved the GVT effect in tumor models.
• RGMb blockade modulated immune responses in the gut, decreasing IFN-γ and increasing IL-5 and IL-10.

Conclusions:

• RGMb plays a critical role in the pathogenesis of GvHD and IBD.
• Blocking RGMb with a specific monoclonal antibody is a promising therapeutic strategy for preventing GvHD and IBD while maintaining the GVT effect.
• Targeting RGMb offers a potential approach to restore gut homeostasis and improve outcomes in HCT patients and IBD sufferers.