Autoimmune diabetes mellitus in the BB rat.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
J P Mordes
Publications and source records attributed to J P Mordes.
Insulin treatment prevents diabetes mellitus but not thyroiditis in RT6-depleted diabetes resistant BB/Wor rats.
Prophylactic insulin administration is known to prevent hyperglycaemia in diabetes prone BB rats and non-obese diabetic mice. This study investigated the effect of insulin treatment on the development of overt diabetes, clinically inapparent anti-islet autoreactivity, and thyroiditis in RT6-depleted diabetes resistant BB rats. Fewer than 1% of these animals develop spontaneous diabetes, but if depleted of RT6- T cells greater than 50% become hyperglycaemic. We treated 30-day-old diabetes resistant rats with anti-RT6.1 monoclonal antibody, exogenous insulin, or both. Up to 60 days of age, 16 of 20 rats given antibody alone became diabetic, compared with 1 of 20 also treated with antibody plus insulin. Up to 110 days of age, only 1 of 10 rats treated with both insulin and antibody between 30 and 60 days became diabetic. Histologic study of non-diabetic insulin plus anti-RT6 antibody treated rats revealed insulitis in 3 of 9 at 60 days old, and insulitis in 3 of 8 and thyroiditis in 6 of 7 at 110 days of age. Non-diabetic animals were also found to harbour autoreactive spleen cells that adoptively transferred diabetes. Splenocytes from 60 or 110-day-old non-diabetic donors that had been treated with insulin and antibody between 30 and 60 days of age induced diabetes in 7 of 13 and 6 of 8 adoptive recipients respectively. We conclude that insulin treatment prevents clinical diabetes in the RT6-depleted diabetes resistant BB rat, but this treatment does not prevent the development of autoreactive cell populations that cause thyroiditis and adoptively transfer diabetes.
Animals↗
Islet cells but not thyrocytes are susceptible to lysis by NK cells.
BB rats develop both pancreatic insulitis and lymphocytic thyroiditis, but whereas spontaneous autoimmune diabetes is common, hypothyroidism is rare. Splenic natural killer (NK) cells from acutely diabetic (AD) BB rats and from athymic nude rats are known to be cytotoxic to rat islet cells in vitro. To investigate possible differential tissue susceptibility to lysis by NK cells or their cytokines such as cytolysin (perforin) or NK cytotoxic factor (NKCF), we used an in vitro 51Cr-release assay to measure the cytotoxicity of splenocytes, cytolysin or NKCF against Wistar Furth (WF) and Fischer 344 (F-344) rat islet cells, and FRTL-5 F-344-derived and WRT Wistar-derived rat thyrocytes. The results demonstrated that spleen cells from AD-BB (RT1u) rats and athymic F-344 nude (RT11) rats are cytotoxic to WF (RT1u) islets and F-344 (RT11) islets, but not to FRTL-5 (RT11) or WRT (class I RT11) thyrocytes. WF and F-344 rat spleen cells were not cytotoxic to any of these cells. Thyrocytes are known to express class II molecules on their surface in chronic thyroiditis. We found that treatment of thyrocytes with interferon-gamma (IFN-gamma) induced class II expression but did not increase the cytotoxicity of splenocytes against these cells. Cytolysin and NKCF were both cytotoxic to islets in a dose dependent manner, but FRTL-5 thyrocytes were resistant to killing by these cytokines. These findings suggest that islet cells and thyrocytes in vitro are differentially susceptible to lysis by NK cells.
Animals↗
Recapitulation of normal and abnormal BB rat immune system development in scid mouse/rat lymphohemopoietic chimeras.
Mice homozygous for the mutation "severe combined immune deficiency" (C.B17-scid/scid) lack functional T and B lymphocytes and readily accept tumor xenografts. Partial lymphohemopoietic scid/human and mouse/rat chimeras have been described, but complete chimerization with thymic engraftment and generation of donor-origin thymocytes has not been achieved. We now report that low-dose irradiation permits the engraftment of BB rat fetal liver stem cells in scid recipients. We observed that BB rat fetal liver cells injected into irradiated scid mice establish a rat hemopoietic system in the scid mouse bone marrow and populate the scid mouse thymus. These stem cells generated rat-origin thymocytes that migrated to the scid mouse spleen, a peripheral lymphoid organ. Finally, we found that xenogeneic chimeras created using fetal liver cells from the abnormal (lymphopenic, diabetes prone) subline of BB rats recapitulated both the quantitative and phenotypic abnormalities of the donor rat. Xenogeneic lymphohemopoietic chimeras established in scid mice may provide a powerful new tool in the study of immune system development and autoimmunity.
Animals↗
Altered expression of diabetes in BB/Wor rats by exposure to viral pathogens.
Autoimmune diabetes mellitus affects greater than 50% of diabetes-prone BB (DP BB) rats but less than 1% of diabetes-resistant BB (DR BB) rats. We report an outbreak of spontaneous diabetes among DR BB rats that coincided with serologic evidence of the onset of viral infection. This apparent link between a change in the environment and the expression of diabetes then led us to study the interaction of environmental exposure to viral pathogens in this disorder with virally seropositive and seronegative populations of BB rats and polyinosinic-polycytidylic acid (poly I:C), an interferon inducer known to accelerate diabetes onset in DP rats. We administered a cytotoxic anti-RT6 monoclonal antibody, poly I:C, or both to DR rats. Depletion of the RT6.1+T-lymphocyte population has previously been shown to induce diabetes and thyroiditis in DR rats. RT6 alone did not induce diabetes in seronegative DR rats, and poly I:C was only weakly effective, but nearly all animals given both reagents became diabetic. When given to seropositive DR rats, either reagent alone induced diabetes; when given to non-BB rats, neither agent was effective. Poly I:C also accelerated the onset of DP diabetes to a greater extent in seropositive than in seronegative rats. We conclude that expression of the genetic predisposition to diabetes present in all BB rats depends on cellular factors that include the presence or absence of regulatory (RT6+) T lymphocytes and modulatory environmental factors including exposure to viral pathogens.
ADP Ribose Transferases↗
T-lymphocyte requirement for diabetes in RT6-depleted diabetes-resistant BB rats.
Diabetes-prone (DP) BB rats develop spontaneous autoimmune insulin-dependent diabetes mellitus (IDDM). The cell populations involved in the expression of diabetes are not precisely known but probably include natural killer (NK) cells, macrophages, and T lymphocytes. Because the DP rat has few lymphocytes of the CD5+/CD+ phenotype, cytotoxic T lymphocytes (Tc) are not believed to be important in the process. Diabetes-resistant (DR) BB rats that are depleted of RT6+ T lymphocytes also become diabetic and provide an additional model of IDDM. We report that diabetes in DR rats depleted of RT6+ T lymphocytes is prevented by the concomitant depletion of either the CD5+ or the CD8+ population. In contrast, coadministration of anti-asialogangliosideM1 (alpha-ASGM1), an antiserum that principally recognizes NK cells, failed to prevent hyperglycemia in RT6-depleted rats. We propose that the initiation of diabetes in both DP and RT6-depleted DR rats is T-lymphocyte dependent. However, the final common pathway leading to autoimmune beta-cell destruction in IDDM may be different in these models. The RT6-depleted DR rat requires a cell that is sensitive to anti-CD8 (possibly a Tc), whereas the DP rat requires an anti-ASGM1-sensitive cell.
ADP Ribose Transferases↗
Insulin dependent diabetes mellitus hypothesis of autoimmunity.
Explore the source record for details and available documents.
Animals↗
Prevention of diabetes in the BB rat by essential fatty acid deficiency. Relationship between physiological and biochemical changes.
Essential fatty acid (EFA) deficiency exerts a striking protective effect in several animal models of autoimmune disease. We now report that EFA deprivation prevents diabetes in the BB rat, an animal model of human insulin-dependent diabetes mellitus. In diabetes-prone (DP)-BB rats, the incidences of spontaneous diabetes and insulitis (the pathological substrate of autoimmune diabetes) were greatly reduced by EFA deficiency. This beneficial effect of the deficiency state was also seen in diabetes-resistant (DR)-BB rats that, after treatment with antibody to eliminate RT6+ T cells, would otherwise have become diabetic. The susceptibility of EFA-deprived DP-BB rats to spontaneous diabetes was restored when they were given dietary supplements of linoleate at 70 d of age (during the usual period of susceptibility), but not when they were repleted beginning at 120 d (after the peak incidence of diabetes). EFA deficiency did lead to growth retardation, but calorically restricted control rats demonstrated that the protective effect of the deficiency state was not a function of decreased weight. To examine the relationship between the biochemical changes of EFA deficiency and its physiological effects in this system, we compared the fatty acid changes that occurred in EFA-deficient animals that did and did not develop diabetes. Nondiabetic animals had significantly lower levels of (n-6) fatty acids (i.e., linoleate and arachidonate) and higher levels of oleate, an (n-9) fatty acid, than did diabetic animals. Levels of 20:3(n-9), the fatty acid that uniquely characterizes EFA deficiency, were similar in both groups, however. Among diabetic EFA-deficient rats, the age at onset of diabetes was found to correlate inversely with the level of (n-6) fatty acids, the least depleted animals becoming diabetic earliest, whereas there was no correlation with levels of 20:3(n-9). Among animals repleted with linoleate beginning at 70 d, restoration of susceptibility to diabetes correlated with normalization of the level of arachidonate. In summary, EFA deprivation reduced the frequency of diabetes in both DP and RT6-depleted DR-BB rats. This protective effect was strongly associated with depletion of (n-6) fatty acids, particularly arachidonate, but not with accumulation of the abnormal 20:3(n-9). Conjecturally, arachidonate and/or a metabolite may play a key role in mediating inflammatory injury in this animal model of autoimmune diabetes.
Animals↗
Morphological and physiological characteristics of pancreas-specific venular permeability induced by Monastral blue B.
Leaky blood vessels in the microcirculation can be detected in vivo by injecting an animal with colloidal pigments such as Monastral blue B (MbB) or carbon black. We have previously used the MbB labeling method in the spontaneously diabetic BB/W or rat and detected increased vascular permeability restricted to the venules of the pancreas. We now report the morphological and physiological characteristics of this phenomenon in additional rat strains. Susceptibility to pancreatic labeling with MbB among strains was found to be a highly variable, heritable characteristic, but in no strain did vessels label in any organ other than the pancreas. Pancreatic labeling by MbB was dose dependent, was observed in both inbred and outbred rats, and was not related to major histocompatibility complex haplotype. Enhanced permeability was induced by MbB within minutes of its administration as a result of the formation of gaps between endothelial cells; these gaps then closed within 15 min. Pretreatment with silica or carrageenan, agents known to affect macrophage function, completely blocked pancreatic MbB venular labeling, but the effect was reversible over a period of several days. We hypothesize that presence of MbB in the pancreatic circulation induces organ-specific venular leakage either by a direct effect on pancreatic endothelial cells or via the local release of a mediator.
Animals↗
Adoptive transfer of autoimmune diabetes and thyroiditis to athymic rats.
We describe the induction of autoimmune diabetes, insulitis, and thyroiditis in athymic rats following injections of major histocompatibility complex compatible spleen cells. Lymphocytes with these capabilities were found in normal rats of the YOS, WAG, PVG, and diabetes-resistant BB strains, and in diabetes-prone BB rats. Adoptive transfer was facilitated by prior in vivo depletion of RT6.1+ regulatory T cells and in vitro mitogen activation of donor spleen cells. By RT6 depleting diabetes-resistant donors and using nude recipients, transfer of diabetes and thyroiditis was accomplished by using fresh, unstimulated spleen cells. The data suggest that organ-specific autoreactive cells may be present to various degrees but suppressed to a variable extent in many rat strains. The equilibrium between autoreactive and regulatory cells appears to determine the expression of autoimmunity.
Animals↗
Plasma from BB/Wor rats increases insulin secretion by perfused rat pancreas.
Diabetes-prone (DP) BB rats develop spontaneous autoimmune diabetes mellitus in the context of multiple abnormalities of humoral and cellular immunity. Diabetes-resistant (DR) BB rats have phenotypically normal immune systems and rarely become spontaneously hyperglycemic, but can be rendered diabetic by in vivo immune elimination of T cells that express the RT6 surface alloantigen. To determine if humoral factors in these animals influence beta-cell function, we studied the effect of BB rat plasma on glucose-induced insulin secretion from the isolated perfused rat pancreas. We found that plasma dialyzed to remove molecules less than 14 kD from nondiabetic DR and DP BB rats significantly enhanced total insulin secretion [4806 +/- 711 ng (+/- SEM; n = 6) and 4968 +/- 1235 ng (n = 7), respectively] from perfused pancreata when compared with the effects of either plasma from Wistar-Furth rats (2585 +/- 336 ng; n = 9) or medium containing no plasma (1862 +/- 92 ng; n = 38). The presence of chemically induced diabetes was also associated with enhanced insulin secretion [3276 +/- 414 ng (n = 8) using alloxan and 3956 +/- 470 ng (n = 7) using streptozocin], but the greatest degree of enhancement was observed with plasma from spontaneously diabetic BB rats (6521 +/- 751 ng; n = 17). The enhancement of insulin secretion by BB rat plasma, both diabetic and nondiabetic (DR and DP), was characterized by preservation of first and second phase hormone release. Heat inactivation of acutely diabetic BB rat plasma did not affect its ability to stimulate insulin secretion. We conclude that the plasma of BB rats, both before and after the onset of autoimmune diabetes mellitus, contains a factor other than complement of greater than or equal to 14 kD that enhances insulin secretion in vitro from the isolated perfused pancreas.
Animals↗
Biochemical studies of RT6 alloantigens in BB/Wor and normal rats. Evidence for intact unexpressed RT6a structural gene in diabetes-prone BB rats.
Lymphocytes bearing the T-lymphocyte differentiation antigen RT6 play an important immunoregulatory role in the development of autoimmune diabetes in BB rats. Immunofluorescence studies suggest that diabetes-prone (DP)- but not diabetes-resistant (DR)-BB rat lymphocytes fail to express RT6 antigen during ontogeny. Two alloantigenic forms of the molecule exist, i.e., RT6.1 and RT6.2; both are linked to cell membranes by a phosphatidylinositol (PI) linkage. In these studies, PI-phospholipase C (PLC) treatment of lymphocytes from BB and normal rats followed by immunoabsorption and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of released proteins with anti-RT6 allotype-specific monoclonal antibodies was performed. RT6.1 in several nondiabetic rat strains was found to consist of a family of nonglycosylated and variably glycosylated molecules: an N-Glycanase-resistant 24,000- to 26,000-Mr peptide and four N-Glycanase-sensitive peptides of 29,000, 31,000, 33,000, and 34,000 Mr. In contrast, RT6.2 was found to be a 24,000- to 26,000-Mr nonglycosylated polypeptide. The electrophoretic pattern of RT6.1 was observed to be the same when the antigen was extracted from W3/25+ (CD4+) versus W3/25- T lymphocytes or from resting versus mitogen-activated cells. A pattern of bands characteristic of the RT6.1 antigen found in normal rat strains was detected after PLC treatment or detergent solubilization of lymphocytes obtained from DR rats. In contrast, no evidence of either RT6 species was found after PLC or detergent treatment of comparable numbers of T lymphocytes from DP-BB rats. Interestingly, T lymphocytes from Wistar-Furth (RT6.2+) x DP (RT6-) F1 crosses were observed to coexpress both RT6.2 and RT6.1 molecules, with the electrophoretic pattern of RT6.1 being similar to that obtained in DR and other rat strains. This study provides biochemical evidence that DP rats may have an intact RT6a structural gene.
ADP Ribose Transferases↗
Autoimmune destruction of islets transplanted into RT6-depleted diabetes-resistant BB/Wor rats.
We report a novel animal model of islet transplantation that distinguishes recurrence of autoimmunity from allograft rejection. In this study, diabetes-resistant (DR) BB rats, less than 1% of which develop spontaneous diabetes, were made hyperglycemic by either a single injection of streptozocin (STZ) or in vivo immune elimination of a regulatory T-lymphocyte subset that expresses the RT6 alloantigen. DR islet grafts were then transplanted into both groups. DR transplants into STZ-induced diabetic DR rats produced long-term normoglycemia. In contrast, DR transplants into DR rats that had been treated with anti-RT6 monoclonal antibody were all destroyed within an average of 4 days. Allogeneic islets transplanted into both STZ-induced and RT6-depleted diabetic DR rats were rejected within a mean of 3 days. We conclude that failure of DR islet grafts in RT6-depleted diabetic DR BB rats represents recurrent autoimmunity.
Animals↗
Lack of systematically found insulin autoantibodies in spontaneously diabetic BB rats.
Insulin autoantibodies (IAAs) occur in newly diagnosed human insulin-dependent diabetes mellitus (IDDM) patients, but their presence in BB rats is controversial, possibly due to assay differences or variability in the animals studied. To resolve this controversy, IAAs were measured in well-characterized inbred BB rats both in radioligand assays with 125I-labeled rat insulin I or II, respectively, and in an enzyme-linked immunosorbent assay (ELISA) with rat insulin as antigen. In prospective studies, a total of 57 serums from 16 diabetes-prone (DP) BB rats were obtained during an interval ranging from 15 wk to the last week before onset and at onset of diabetes. At comparable ages, 21 serums were obtained from 8 DP BB rats not developing diabetes, and 70 matched serums were obtained from 19 diabetes-resistant (DR) BB rats. Levels of antibody binding increased slightly with increasing age in DP and matched DR rats. Two rats were positive at onset of IDDM in all assays but not in earlier samples. Otherwise, only few isolated serums from both types of rats regardless of diabetes had increased binding in one of the assays. In a cross-sectional study, the insulin-binding levels in 150-day-old DP rats (n = 20) that had not yet developed diabetes did not correlate with insulitis present in 3 of 20 rats and did not differ from 150-day-old DR BB rats (n = 20).(ABSTRACT TRUNCATED AT 250 WORDS)
Aging↗
Intrinsic cytotoxicity of natural killer cells to pancreatic islets in vitro.
BB rats develop spontaneous autoimmune insulin-dependent diabetes mellitus that is similar to human insulin-dependent diabetes. In this study, we used an in vitro islet cell cytotoxicity assay to study the possible role of natural killer (NK) cells and their soluble effector molecules in this disorder. First, the results demonstrated that in vivo treatment of acutely diabetic BB rats with anti-asialogangliosideM1 (an NK cell antiserum) but not with anti-T-lymphocyte antibodies reduces spleen cell cytotoxic activity to islets in vitro. Flow microfluorometry (FMF)-sorting experiments were then used to confirm that the splenic cytotoxic effector cell in acutely diabetic BB rats is a CD8+/CD5- NK cell. Further analysis demonstrated that both FMF-sorted NK cell populations from Wistar-Furth rats and unfractionated spleen cells from athymic nu/nu rats with high intrinsic NK cell activity also exhibit high islet cell cytotoxic activity in vitro. Finally, we found that the kinetics and differential cytotoxic activity of NK cells toward islets in vitro could be mimicked by NK cell culture supernatants containing high levels of NK cytotoxic factor (NKCF). The islet cytotoxic activity of these culture supernatants was specifically inhibited by the addition of anti-NKCF monoclonal antibody. These results demonstrate that NK cells from diabetic and nondiabetic rats are cytotoxic to islet cells in vitro. They further suggest that this cytotoxic effect may be mediated in part through the production and release of soluble factors such as NKCF.
Animals↗
Prevention of diabetes in BB/Wor rat by single transfusion of spleen cells. Parameters that affect degree of protection.
Previous studies have shown that multiple transfusions of spleen cells from histocompatible nondiabetic donors prevent autoimmune diabetes mellitus in diabetes-prone (DP) BioBreeding/Worcester (BB/Wor) rats. In this study, a single transfusion of greater than or equal to 50 x 10(6) cells from either diabetes-resistant (DR) BB/Wor or Wistar-Furth (WF) rats substantially reduced the incidence of diabetes when given to DP rats 27 or 46 days old but not 61 days old. Transfusion and protection were associated with the appearance of RT6+ donor lymph node cells in recipient rats. In vivo depletion of RT6+ T-lymphocytes in 150-day-old protected animals did not produce diabetes. DR BB/Wor and WF spleen cells were equally efficacious when given either intraperitoneally or intravenously. Mitogen-activated spleen cells were relatively less effective than untreated cells. We conclude that BB rat diabetes can be prevented by one transfusion of spleen cells from histocompatible DR and WF donors, and that the protective effect is dependent on recipient age and cell dose. The effect may be mediated by a population of RT6+ T-lymphocytes that, during a critical developmental period, regulate the expression of autoimmunity in these animals.
Age Factors↗
Effects of irradiation on diabetes in the BB/Wor rat.
Lymphoid irradiation is known to prevent spontaneous autoimmune diabetes in susceptible BB rats. The present studies investigated further the effects of radiation in diabetes prone (DP) and resistant (DR) BB/Wor rats, and histocompatible Yoshida (YOS) rats. Single doses of total body gamma irradiation (125-600 rads) induced diabetes within 22-44 days in 20 of 102 (20%) 30 day old DR rats, less than 1% of which develop the disease. Radiation was also associated with (1) a reduction in the ratio of W3/25+ to OX8+ peripheral blood lymphocytes within 2 weeks, and (2) a decreased percentage of lymph node cells expressing the RT6.1 surface alloantigen 3-4 weeks after treatment. Similar doses of irradiation did not alter the frequency or age at onset of diabetes in DP rats, and did not induce diabetes in YOS rats. When a single dose of 250 or 500 rads of gamma irradiation was followed by injection of mitogen activated spleen cells from acutely diabetic rats to adoptively transfer diabetes, 16 of 19 (84%) DR and 8 of 14 (57%) YOS rats became diabetic. Long term exposure to ultraviolet irradiation (UVB) did not alter the frequency or age at onset of diabetes in either DP or DR rats. We conclude that there may exist a population of regulatory cells relatively sensitive to gamma irradiation that play a role in determining the susceptibility of rats to autoimmune diabetes mellitus.
Animals↗
Absence of RT6+ T cells in diabetes-prone biobreeding/Worcester rats is due to genetic and cell developmental defects.
Diabetes-prone BB/Wor (DP) rats lack the RT6+ peripheral T cell subset whereas diabetes-resistant BB/Wor rats have normal numbers of RT6+ T cells. Lymphocyte transfusion experiments and in vivo depletion studies have demonstrated that RT6+ T cells have an important regulatory role in the pathogenesis of insulin-dependent diabetes mellitus in BB/Wor rats. In the present study, the results of genetic complementation studies indicate that the DP rat contains an intact RT6 gene, but fails to express the RT6.1 alloantigen in the functional absence of an accessory factor (provided by RT6+ cells). At the cellular level, irradiation chimeras demonstrate that the absence of RT6+ T cells in DP rats is due to an intrinsic defect that results in abnormal development and/or differentiation of prothymocytes into RT6+ T cells. The inability of DP prothymocytes to generate RT6+ T cells is not due to serum autoantibodies, lack of accessory cells, or to the presence of inhibitory cells. Inasmuch as DP bone marrow can transfer the susceptibility for diabetes to irradiated recipients, our present results suggest that an important predisposing factor for insulin-dependent diabetes mellitus in DP rats is the inability of DP prothymocytes to generate RT6+ T cells.
Animals↗