Immunomodulation Followed by Antigen-Specific T_reg Infusion Controls Islet Autoimmunity

Area of Science:

• Immunology
• Endocrinology
• Cell Biology

Background:

• Type 1 diabetes (T1D) is an autoimmune disease requiring therapies that restore self-tolerance without chronic immunosuppression.
• CD4+Foxp3+ regulatory T cells (Tregs) are crucial for immune tolerance, but their clinical application in T1D is hindered by poor engraftment.
• Previous studies indicated that Treg engraftment requires ablative host conditioning.

Purpose of the Study:

• To evaluate nonablative, combinatorial immunotherapies for enhancing Treg engraftment and efficacy in the nonobese diabetic (NOD) mouse model of T1D.
• To investigate the impact of anti-CD3 (αCD3), cyclophosphamide (CyP), and IL-2/JES6-1 antibody complex on Treg engraftment and therapeutic outcomes.

Main Methods:

• NOD mice were treated with αCD3 alone, or in combination with CyP and/or IL-2/JES6-1 antibody complex.
• T cell depletion, Treg rebound kinetics, and donor Treg engraftment were assessed.
• Therapeutic efficacy was evaluated by monitoring diabetes remission and islet autoimmunity control.

Main Results:

• αCD3 treatment depleted both conventional T cells (Tconv) and Tregs, followed by Treg rebound.
• Donor Treg engraftment failed even with IL-2 support after αCD3 alone.
• Combining αCD3 with CyP enhanced donor Treg engraftment but did not reverse diabetes.
• Infusion of autoantigen-specific Tregs after αCD3 alone led to robust Treg engraftment and complete diabetes remission in all treated mice.

Conclusions:

• Nonablative combinatorial therapy using αCD3 can be optimized for Treg engraftment.
• Autoantigen-specific Tregs are essential for reversing autoimmune diabetes.
• This approach offers a promising strategy for T1D treatment without long-term immunosuppression.