Ph.D. Projects


1. Accomplishing type 1 diabetes immune regulation in the pancreas
Type 1 diabetes (T1D) is the result of a T-lymphocyte–dependent autoimmune process that specifically destroys the insulin-secreting beta-cells of the pancreas. Blockade of autoaggressive T cells and re-establishment of tolerance to the beta-islets is fundamental for the definitive cure of autoimmune diabetes. Immunological tolerance can be achieved by the induction of a subset of T cells, named T regulatory cells (Tregs), that specifically suppress the effector T cells reacting against pancreatic beta-islets, while leaving the rest of the immune system intact. An altered balance between pathogenic and regulatory pathways in autoimmunity has been hypothesized and at times demonstrated in peripheral blood of T1D patients. However, for obvious reasons, our knowledge at the site targeted by the autoimmune attack (i.e. the pancreas) in humans is scanty.
We have the unique opportunity to collect pancreatic lymph nodes from T1D patients and from non-diabetic controls. This cell source will be used to extensively characterize the immune responses of T1D individuals in their target organ.
This study will:
1) provide crucial information regarding the immunological status of the target organ in T1D subjects, 2) lead to the identification of new disease-specific markers, and 3) define whether regulatory T cell-based immunotherapy has a real potential to succeed in T1D individuals.

2. Tolerance induction after pancreatic islet transplantation
 Allogenic pancreatic islet transplantation is a possible therapeutic approach for the cure of type 1 diabetes in alternative to insulin replacement therapy. In the last years a steroid-free immunosuppressive treatment (known as the “Edmonton protocol”) has been proven to be successful in diabetic patients transplanted with allogeneic islets. Continuous drug administration allows long-term graft survival with normal insulin levels for several months. However, this treatment has all the disadvantages associated with a sustained state of immunosuppression. A valid alternative to immunosuppressive regimens is the induction of transplantation tolerance mediated by T regulatory cells (Tregs). ??We demonstrated that treatment with rapamycin+IL-10 blocks pancreatic islet rejection in chemically-induced diabetic BALB/c mice through the induction of Ag-specific Tr1 cells (Battaglia et al. Diabetes 2006). However, rapamycin+IL-10 treatment in the more stringent model of diabetic NOD mice transplanted with allogeneic islets only delays graft rejection. The presence of auto-aggressive T effector cells pre-existing the transplant is likely to be the major limitation for the long-term success of rapamycin+IL-10 treatment in NOD mice. A depleting agent able to eliminate pre-activated islet-destroying T cells may be required for long-term graft function. Antibodies targeting CD45RB have been shown to prevent renal and islet allograft rejection. Reduction of CD45RBhigh cells and up-regulation of CTLA-4 is one possible mechanism responsible for preventing allograft rejection. Anti-CD45RB mAb + rapamycin+IL-10 treatment prolonged allograft survival in NOD mice but still did not promote long term tolerance.
New combinational approaches are actively under investigation to reach immunological tolerance in transplanted NOD mice. We recently showed that Tr1 cells can transfer tolerance in preclinical models of islet transplantation and their therapeutic efficacy is highly dependent on their antigen specificity. A combinational therapy made of immunosuppressive treatments + adoptive transfer of ex vivo generated Tr1 cells will be tested in diabetic NOD mice transplanted with allogeneic islets.  We will monitor and characterize the induced tolerance. In parallel, we will define where the Tr1 cells migrate once transferred in vivo, whether their phenotype remain stable, and how they function.?This study will contribute to identify the best protocol for successful islet transplantation in diabetic patients and it will advance our knowledge on the mechanism of transplantation tolerance mediated by Tregs.