(H-315) Immune Modulation for the Treatment of Type 1 Diabetes

INTRODUCTION
The deficiency or mutation of co-inhibitory checkpoints is associated with the autoimmune diabetes progression. Introducing some co-inhibitory checkpoint molecules to the islet can attenuate diabetogenic T cells. Thus, reversal of early onset hyperglycemia could be achieved. In previous work, we successfully found that pancreatic beta (β) cells containing sufficient co-inhibitory checkpoint molecules can reverse early-onset hyperglycemia in NOD mice by attenuating the activity of diabetogenic T cells. In this work, we found that the checkpoint molecules-bearing pancreatic extracellular matrix (PAN-ECM) can also effectively slow the progression of hyperglycemia and prolonged the overall survival. Nevertheless, there are many checkpoint molecules that play an important role in immune homeostasis, and then a combination of different checkpoint molecules may have a better reversal effect on new-onset diabetes. To achieve this goal, we bioengineer PAN-ECM with different checkpoint molecules, and then created an immunogenic pancreas microenvironment by subcutaneously injecting the PAN-ECM mixed with β cells proximal to the pancreatic lymph nodes. Eventually, strong antigen-specific effector T cell suppression is evoked by the interaction of PAN-ECM with diabetogenic T cells.
MATERIALS AND METHODS
PAN-ECM was isolated from rat pancreas through a shaking-decellularization. Next Azide-modified PAN-ECM was generated by carbodiimide /N-hydroxysuccinimide (EDC/NHS) reaction with Azide-PEG8-NHS. Before attaching checkpoints to Azide-modified PAN-ECM, we firstly prepared DBCO-functionalized checkpoints bioconjugates via bioorthogonal click reaction between checkpoints and DBCO-Dendrimer. Then Checkpoints-functioned PAN-ECM were prepared by bioorthogonal click reaction between DBCO-functionalized checkpoints bioconjugates and Azide-functionalized PAN-ECM. The therapeutic efficiency of different subcutaneous (s.c.) injectable Checkpoints-functioned PAN-ECM plus β cells was evaluated in newly diabetic NOD female mice 2-3 days after diabetes onset. Also, two booster was administered 2 weeks and 4 weeks after the initial treatment.
CONCLUSION
When we treated newly diabetic NOD female mice with PD-L1, HVEM, and FasL-functioned PAN-ECM, 50% of the PD-L1-functioned PAN-ECM treatment group reversed to normoglycemia (Figure 1A). And half of the HVEM-functioned (Figure 1B) and FasL-functioned PAN-ECM-treated mice (Figure 1C) were diabetic-free for 100 days.
We next investigated whether all three checkpoints simultaneously modified to PAN-ECM could be used as a therapeutic vaccine to reverse early-onset hyperglycemia. The results demonstrated that, in comparison to three monofunctionalized PAN-ECM, PD-L1/HVEM/FasL-functioned PAN-ECM allowed a more potent and concomitant suppress of a multitude of immune checkpoint pathways, eliciting a more effective induction of antigen-specific T cell exhaustion (Figure 1D).