-Cell Function in Mice Injected with Mononuclear Splenocytes from Multiple-Dose Streptozotocin Diabetic Mice

Abstract

Multiple low doses of streptozotocin (mid sz 40 mg/kg/day, five consecutive days) induce autoimmune diabetes in mice. The aim of the present work was to study beta-cell function in mice injected with splenocytes from mid-sz diabetic mice. Mononuclear splenocytes (MS) from control or diabetic donors were injected into syngeneic C57BL/6J healthy mice (5 x 10(7) MS, ip). MS from diabetic donors did not produce basal hyperglycemia, but they induced abnormal ip glucose tolerance in recipient mice. These "diabetic" MS were also preferentially trapped by the recipient's pancreas. Perifused pancreas from mice injected with MS from mid sz-diabetic donors showed a diminished first and second phase of glucose-induced insulin secretion after 15 days of the cell injection. At this time, pancreatic insulin content among MS recipients did not differ from that found in controls or diabetic donors. Diabetic MS treated with Mitomycin C prior to transfer did not inhibit insulin secretion in recipient mice. Injection of MS from mice made diabetic by a single high sz dose (200 mg/kg) did not induce any alterations of the insulin secretion in recipients. There is enough evidence when using athymic and euthymic (BALB/c nu/nu and +/nu) mice to suggest that proliferation of the injected splenocytes enhanced the progression to the diabetic state, and that both donor and recipient T lymphocytes played an important part in this progression. The results suggest that injection of MS from mid sz-diabetic mice interfere with glucose-stimulated insulin secretion in recipient mice and provide a basis for the study of the mechanisms involved in the onset and modulation of autoimmune pancreatic aggression.

Early Manifestations in Multiple-low-dose Streptozotocin-induced Diabetes in Mice

“…When MSs were treated with mitomycin C before transfer, their effect on recipients was completely abolished, implying that transferred splenocytes should proliferate in recipient mice to be able to have a pathogenic effect. 9 Enghofer et al 34 showed that transfer of lymphocytes derived from spleens of mld-SZ mice resulted in increased lymphocyte rolling and endothelial adhesion only in islets of recipient mice pretreated with a single subdiabetogenic dose of streptozotocin. It has been suggested that the pool of transferred splenic lymphocytes from mld-SZ mice contain immunologically activated islet-specific cells that trigger the immune aggression in this diabetic model.…”

“…Arata et al 9 showed that MSs from mld-SZ diabetic mice induced abnormal glucose tolerance and insulin secretion impairment in healthy syngeneic recipients and presented a specific homing toward pancreas with both donor and recipient T lymphocytes, playing an important role in this process. When MSs were treated with mitomycin C before transfer, their effect on recipients was completely abolished, implying that transferred splenocytes should proliferate in recipient mice to be able to have a pathogenic effect.…”

“…[2][3][4][19][20][21][22] In addition, it mimics some basic aspects of recent-onset type 1 diabetes in human patients. 23 The immunologic component in the mld-SZ diabetic model is highlighted by the absence of diabetes development in T-cell-deficient mice and by the protective effects of immunosuppressive or anti-inflammatory compounds 4,9,22,24,25 or vaccination with modified autoreactive lymphocytes. 5,6 It has been shown that mld-SZ administration depresses some constituents of the immune system, such as CD4 + T cells and some T-cell reactions, whereas macrophage activity and nonspecific cytotoxicity and production of interferon-g are activated.…”

“…10 MSs were aseptically isolated by shredding the spleens with steel wire mesh followed by 2 washes in sterile NaCl 154 mmol/L solution. 8,9 MSs were obtained using Lymphoprep gradients (Nycomed Pharma, Oslo, Norway) and then washed 3 times with sterile saline solution. Cell viability was assayed by the Trypan blue exclusion test 11 and was 95% to 98%.…”

“…In these mice, a diminished insulin secretion is present 15 days after the transfer procedure, and a preferential trapping of transferred lymphocytes in islets of recipient mice was observed. 5,6,8,9 The aim of this study was to investigate the ability of mononuclear spleen cells (MSs) from treated mice to impair insulin secretion in normal recipient mice or in cultured dispersed rat islet cells at different days after mld-SZ administration. With this purpose, we studied insulin secretion patterns in mice transferred with MSs isolated from mld-SZ donors and the capacity of MSs from mld-SZ mice to exert an in vitro antib-cell immune aggression.…”