Diabetes and other autoimmune endocrine diseases
The development of novel approaches to selectively control antigen(Ag)-specific effector T (Teff) cell responses and to restore tolerance represents an ambitious goal for the management of type 1 diabetes (T1D). Compelling evidences support the prominent role of dendritic cells (DC) in promoting T-cell tolerance. Methods to generate clinical grade products have been developed, leading to the application of tolerogenic (tol) DC-based therapy in clinical trials with promising results. With the aim of generating genetically engineered tolDC suitable for cell-based therapy to restore tolerance to islet antigens (Ag) in T1D, we designed lentiviral vectors (LV) which enforce expression of HLA-class-II restricted epitopes in the absence (DCLV-Ag) or presence of tolerogenic molecules (i.e., IL-10 or IDO, tolDCLV-Ag), thanks to the fusion of human invariant chain (lip33) to known immunodominant peptides of T1D Ag. HLADQ8+ human monocytes engineered with LVs encoding for InsB9-23 were differentiated in vitro in DC. When IL-10 was co-expressed, the resulting cell population acquired a tolDC phenotype, (DCs were CD14+ILT4hiCD141+CD163+), and constitutively produced high amounts of IL-10. Overexpression of IDO resulted in immature DCs able to degrade tryptophan and produce L-kynurenine in cell culture supernatants. DCLV-Ag were able to induce Ag-specific autologous CD4+ T cell proliferation in vitro, while DC co-encoding for IL-10 induced a hypo-proliferative response and promoted the expansion of Ag-specific CD49b+LAG-3+ Tr1-like cells. Our preliminary data indicate that human tol-DCLV-Ag modulate autoAg-specific T cell responses in vitro. The success of our strategies will help designing a safe and efficient DC-based cell therapy.