OBJECTIVETo investigate the role of T cell and its subsets in the induction of insulitis and type 1 diabetes mellitus (T1DM) in BALB/c mice.

METHODSAutoimmune diabetes mellitus was developed by intraperitoneal injection of 40 mg/kg streptozotocin (STZ) daily for 5 consecutive days in BALB/c mice as sources of donor cells. Spleen cells from diabetic mice were then cultured for 7 days in the stimulation of interleukin-2 (IL-2) to harvest diabetogenic T cells, which were subsequently transferred into normal BALB/c mice recipients. MTT, ELISA, and HE staining were used to analyze the lymphocyte proliferation, cytokine (IL-2, interferon-gamma, IL-4, and IL-10) levels, and pathological changes in pancreatic islets.

RESULTSAs few as 3 x 10(6) diabetogenic T cells successfully induced diabetes mellitus in recipients pretreated with STZ twice, whereas transfer of equal amount of normal splenocytes, T cell-depleted diabetogenic splenocytes, or diabetogenic CD4+ T cells alone in recipients receiving STZ twice pretreatment was proved not to induce diabetes mellitus either. A markedly increased lymphocyte proliferation, high levels of interferon-gamma and IL-2 in the supernatants of diabetogenic T cells were observed. In addition, a markedly enhanced lymphocyte proliferation, a high level of interferon-gamma secretion in serum, and numerous lymphocytes infiltration in pancreatic islets were detected in the diabetic mice induced by diabetogenic T cells transfer.

CONCLUSIONSA novel T1DM murine model is established in STZ-pretreated BALB/c mice by adoptive transfer of diabetogenic T cells. CD4+ T cells with interferon-gamma may promote the onset of diabetes mellitus.

Animals ; Blood Glucose ; metabolism ; Cytokines ; immunology ; Diabetes Mellitus, Experimental ; metabolism ; pathology ; Diabetes Mellitus, Type 1 ; immunology ; pathology ; Disease Models, Animal ; Islets of Langerhans ; cytology ; metabolism ; pathology ; Male ; Mice ; Mice, Inbred BALB C ; T-Lymphocytes ; cytology ; immunology

Type 1 diabetes mellitus is caused by the autoimmune destruction of beta cells within the islets. In recent years, innate immunity has been proposed to play a key role in this process. High-mobility group box 1 (HMGB1), an inflammatory trigger in a number of autoimmune diseases, activates proinflammatory responses following its release from necrotic cells. Our aim was to determine the significance of HMGB1 in the natural history of diabetes in non-obese diabetic (NOD) mice. We observed that the rate of HMGB1 expression in the cytoplasm of islets was much greater in diabetic mice compared with non-diabetic mice. The majority of cells positively stained for toll-like receptor 4 (TLR4) were beta cells; few alpha cells were stained for TLR4. Thus, we examined the effects of anti-TLR4 antibodies on HMGB1 cell surface binding, which confirmed that HMGB1 interacts with TLR4 in isolated islets. Expression changes in HMGB1 and TLR4 were detected throughout the course of diabetes. Our findings indicate that TLR4 is the main receptor on beta cells and that HMGB1 may signal via TLR4 to selectively damage beta cells rather than alpha cells during the development of type 1 diabetes mellitus.
Animals ; Diabetes Mellitus, Type 1/immunology/*metabolism/pathology ; Female ; Gene Expression Regulation ; Glucagon-Secreting Cells/immunology/metabolism/pathology ; HMGB1 Protein/*genetics/metabolism ; Humans ; Immunity, Innate ; Insulin-Secreting Cells/immunology/metabolism/*pathology ; Macrophages/immunology/pathology ; Mice ; Mice, Inbred C57BL ; Mice, Inbred NOD ; Necrosis ; Protein Binding ; Signal Transduction ; Toll-Like Receptor 4/*antagonists & inhibitors/genetics/immunology