Toxicological and immunological evaluation of the immunosuppressant 15-deoxyspergualin in BALB/c mice: an in vivo and in vitro study

Prevention of type I diabetes in the non-obese diabetic (NOD) mouse with 15-deoxyspergualin (15-DS) or 15-DS + cyclosporin A (CyA)

By selectively inbreeding diabetic individuals, we have been able to establish an NOD mouse population with a genetic predisposition towards insulin-dependent diabetes mellitus (IDDM) in approximately 100% of cases. We examined the preventive effect of 15-DS or 15DS + CyA on developing IDDM in these animals. Whereas 15-DS has been proved to be effective in preventing diabetes (significant decrease of the diabetic risk ratio to 0.368 and a reduction of the incidence of the disease to 46.7%), combined treatment with CyA did not produce any additional benefit.

Impact of 15-deoxyspergualin on effector cells in experimental autoimmune diseases of the nervous system in the Lewis rat

The influence of the immunosuppressive antibiotic agent 15-deoxyspergualin (DSG) on macrophages and autoreactive T helper lymphocytes from Lewis rats was analysed in vitro and in vivo. DSG did not inhibit antigen- or mitogen-induced proliferation of encephalitogenic or neuritogenic T helper cell lines in vitro. However, the presence of DSG during in vitro activation of the T cells strongly suppressed or completely abrogated their capacity to induce encephalitis (EAE) or neuritis (EAN) after adoptive transfer to naive rats, although expression of activation markers or adhesion molecules on the T line blasts was not down-regulated by DSG. Like activation-induced T cell proliferation, IL-2-dependent growth of CD4+ T line cells was not affected by DSG. Preincubation of CD4+ T line cells in DSG during IL-2-driven proliferation for 48 h, however, inhibited the subsequent antigen- but not mitogen-induced activation of these T cells, although neither density of T cell receptors nor other surface molecules involved in antigen recognition were lowered on the cells exposed to DSG. Similar to its effect in vitro, in vivo administration of DSG for 10 days even at a concentration with cumulative toxicity did not suppress in vitro proliferation of spleen cells induced by mitogen or a mitogenic combination of anti-CD2 antibodies. Furthermore, spleen cell and peripheral blood lymphocyte (PBL) surface antigens, particularly MHC molecules, were not altered by long-term treatment with DSG for 30 days. While there was a slight reduction in the number of polymorphonuclear cells in both populations, the proportion of the different leucocyte subpopulations remained unchanged. In contrast to the strong functional impact of DSG on autoreactive T helper cells, the drug did not inhibit the oxidative burst of macrophages or their MHC antigen expression. This study demonstrates a clear inhibitory effect of DSG on CD4+ T lymphocytes, but not macrophages. It provides an explanation for recent observations of a strong immunosuppressive in vivo effect of DSG on transplantation rejection and experimental autoimmune diseases, despite a normal mitogen response of T cells exposed to DSG in vivo and in vitro.

Protection from experimental autoimmune thyroiditis in CBA mice with the novel immunosuppressant deoxyspergualin

The effects of the novel immunosuppressant Deoxyspergualin (DSP) on the development of experimental autoimmune thyroiditis (EAT) in CBA mice were studied. For EAT induction, the mice were immunized with 100 micrograms of porcine thyroglobulin (p Tg) emulsified in CFA on day 0 and in IFA, for boosting, on day 14. Twenty-eight days after primary immunization, histological and serological signs of EAT occurred in control mice treated with PBS which showed marked lymphoid infiltration of the thyroid glands along with increased serum titres of anti-pTg antibodies. Development of both these EAT features was significantly suppressed when the mice were treated with 2.5 mg/kg body weight DSP, given daily, five times a week, from day -2 to day +28 after immunization. The effect appeared to be dose-dependent and DSP was ineffective when given under the same experimental conditions at the dose of 0.5 mg/kg body weight. No DSP-toxic effects could be observed during the experiment. These results provide further evidence for the powerful immunosuppressive properties of DSP and suggest that this drug may be used in the treatment of autoimmune thyroid diseases and other T-cell mediated autoimmune disorders in humans.

Prevention of cyclophosphamide-induced diabetes in the NOD/WEHI mouse with deoxyspergualin

Ten out of 20 (50%) 17-week-old female NOD/WEHI mice developed an acute form of autoimmune diabetes when injected with two large doses of cyclophosphamide (CY), given at 14-day intervals. If these mice were treated under a prophylactic regimen with 2.5 mg/kg body weight per day of the novel immunosuppressant deoxyspergualin (DSP) the onset of diabetes was completely prevented. Moreover, DSP-treated animals showed reduced signs of pancreatic insulitis, had lower percentages of splenic lymphoid cells (SLC) expressing IL-2 receptors and Ly-6C antigens on their surfaces, and these cells released lower amounts of interferon-gamma (IFN) when stimulated in vitro. These data, providing evidence for the capacity of DSP to protect NOD/WEHI mice from experimental autoimmune diabetes and to modulate histo-immunological pathogenic pathways, indicate DSP as a drug of potential interest in the treatment of human insulin-dependent diabetes mellitus.

The effects of deoxyspergualin on the development of diabetes in diabetes-prone BB rats

The effects of the administration of the recently discovered immunosuppressant 15-Deoxyspergualin (DSP) on the development of insulin-dependent diabetes mellitus (IDDM) in diabetes-prone BB rats were studied. The data show that 2 mg/kg body weight DSP, administered six times a week from the 30th day up to the 105th day of age, significantly reduced the incidence of diabetes in diabetes-prone BB rats as compared with the PBS-injected controls. The drug was also able to reduce the signs of pancreatic insulitis and the percentages of W3/25+ and OX6+ splenocytes. Interruption of the treatment resulted in a later onset of diabetes in a high percentage of animals within 41 days. These findings suggest that 15-DSP may temporarily reverse the pathogenic mechanisms leading to beta cell destruction and autoimmune diabetes in a well-known experimental model of human insulin-dependent diabetes mellitus.