Transfusion of Apoptotic β-Cells Induces Immune Tolerance to β-Cell Antigens and Prevents Type 1 Diabetes in NOD Mice

Abstract

In vivo induction of β-cell apoptosis has been demonstrated to be effective in preventing type 1 diabetes in NOD mice. Based on the notion that steady-state cell apoptosis is associated with self-tolerance and the need for developing a more practical approach using apoptotic β-cells to prevent type 1 diabetes, the current study was designed to investigate apoptotic β-cells induced ex vivo in preventing type 1 diabetes. The NIT-1 cell line serves as a source of β-cells. Apoptotic NIT-1 cells were prepared by ultraviolet B (UVB) irradiation. Three weekly transfusions of UVB-irradiated NIT-1 cells (1 × 10⁵/mouse) or PBS were used to determine whether transfusions of UVB-irradiated NIT-1 cells induce immune tolerance to β-cell antigens in vivo and prevent type 1 diabetes. The suppression of anti–β-cell antibodies, polarization of T-helper (Th) cells, and induction of regulatory T-cells by UVB-irradiated NIT-1 cell treatment were investigated. The transfusions of apoptotic NIT-1 cells suppress anti–β-cell antibody development and induce Th2 responses and interleukin-10–producing regulatory type 1 cells. Importantly, this treatment significantly delays and prevents the onset of diabetes when 10-week-old NOD mice are treated. Adoptive transfer of splenocytes from UVB-irradiated NIT-1 cell–treated mice prevents diabetes caused by simultaneously injected diabetogenic splenocytes in NOD-Rag^−/− mice. Moreover, the proliferation of adoptively transferred carboxyfluorescein diacetate succinimidyl ester–labeled β-cell antigen–specific T-cell receptor–transgenic T-cells in UVB-irradiated NIT-1–cell treated mice is markedly suppressed. The transfusion of apoptotic β-cells effectively protects against type 1 diabetes in NOD mice by inducing immune tolerance to β-cell antigens. This approach has great potential for immune intervention for human type 1 diabetes.