Antibodies to a 64,000 Mr human islet cell antigen precede the clinical onset of insulin-dependent diabetes.

Antibodies in sera from newly diagnosed insulin-dependent diabetes mellitus (IDDM) patients are directed to a human islet cell protein of relative molecular mass (Mr) 64,000. Since IDDM seems to develop after a prodromal period of beta-cell autoimmunity, this study has examined whether 64,000 Mr antibodies could be detected in 14 individuals who subsequently developed IDDM and five first degree relatives who have indications of altered beta-cell function. Sera were screened by immunoprecipitation on total detergent lysates of human islets and positive sera retested on membrane protein preparations. Antibodies to the 64,000 Mr membrane protein were consistently detected in 11/14 IDDM patients, and in all 5 first degree relatives. 10 IDDM patients were already positive in the first samples, obtained 4-91 mo before the clinical onset of IDDM, whereas 1 patient progressed to a high 64,000 Mr immunoreactivity, at a time where a commencement of a decline in beta-cell function was detected. 64,000 Mr antibodies were detected before islet cell cytoplasmic antibodies (ICCA) in two patients. In the control groups of 21 healthy individuals, 36 patients with diseases of the thyroid and 5 SLE patients, the 64,000 Mr antibodies were detected in only one individual, who was a healthy sibling to an IDDM patient. These results suggest that antibodies against the Mr 64,000 human islet protein are an early marker of beta-cell autoimmunity and may be useful to predict a later development of IDDM.     

Presented antigen from damaged pancreatic β cells activates autoreactive T cells in virus-mediated autoimmune diabetes

The induction of autoimmunity by viruses has been attributed to numerous mechanisms. In mice, coxsackievirus B4 (CB4) induces insulin-dependent diabetes mellitus (IDDM) resembling the final step of disease progression in humans. The immune response following the viral insult clearly precipitates IDDM. However, the molecular pathway between viral infection and the subsequent activation of T cells specific for islet antigen has not been elucidated. These T cells could become activated through exposure to sequestered antigens released by damaged beta cells, or they could have responded to factors secreted by the inflammatory response itself. To distinguish between these possibilities, we treated mice harboring a diabetogenic T cell repertoire with either the islet-damaging agent streptozotocin (STZ) or poly I:C, which nonspecifically activates T cells. Significantly, only treatment of mice with STZ resulted in IDDM and mimicked the effects observed following CB4 infection. Furthermore, antigen-presenting cells from STZ-treated mice were shown to directly activate autoreactive T cells and induce diabetes. Therefore, the primary role of CB4 in the precipitation of IDDM is to damage tissue, causing release and presentation of sequestered islet antigen. These events stimulate autoreactive T cells and thereby initiate disease.     

Cytotoxic T cells specific for glutamic acid decarboxylase in autoimmune diabetes

Insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease that results in the destruction of the pancreatic islet beta cells. Glutamic acid decarboxylase (GAD) has been recently indicated as a key autoantigen in the induction of IDDM in nonobese diabetic mice. In human diabetes, the mechanism by which the beta cells are destroyed is still unknown. Here we report the first evidence for the presence of GAD-specific cytotoxic T cells in asymptomatic and recent diabetic patients. GAD65 peptides displaying the human histocompatibility leukocyte antigen (HLA)-A*0201 binding motif have been synthesized. One of these peptides, GAD114-123, binds to HLA-A*0201 molecules in an HLA assembly assay. Peripheral blood mononuclear cells from individuals with preclinical IDDM, recent-onset IDDM, and from healthy controls were stimulated in vitro with the selected peptide in the presence of autologous antigen-presenting cells. In three cases (one preclinical IDDM and two recent-onset IDDM), we detected specific killing of autologous antigen-presenting cells when incubated with GAD114-123 peptide or when infected with a recombinant vaccinia virus expressing GAD65. These patients were the only three carrying the HLA-A*0201 allele among the subjects studied. Our finding suggests that GAD- specific cytotoxic T lymphocytes may play a critical role in the initial events of IDDM.     

Studies of concanavalin A in nonobese diabetic mice. I. Prevention of insulin-dependent diabetes

Concanavalin A (Con A) administered in vivo inhibited the development of insulin-dependent diabetes mellitus (IDDM) in nonobese diabetic mice. By experimental day 310 only one of 10 Con A-treated animals had developed IDDM compared to six of 11 cohort controls receiving buffered saline and 65% of colony controls. Treatment consisted of an initial 70-day course of Con A at a dose of 10 micrograms/g b. wt., i.p. in sterile saline every other day. After two deaths occurred in the Con A group, treatment was stopped at day 70. The remaining animals were given two 1-week booster doses beginning on experimental days 118 and 189. The single animal in the Con A group that eventually developed IDDM at day 293 had not received an injection for 107 days. Histological examination revealed peri-islet lymphocytosis but no islet infiltration in the Con A group. Surviving control animals showed both peri-islet and islet infiltrates. One-week Con A treatment significantly suppressed in vitro responses of spleen cells to Con A and allogeneic lymphocytes. The treatment increased the frequency of "blast-sized" cells in vivo and decreased the CD4+/CD8+ ratio among resting splenocytes. It is concluded that polyclonal T cell activation by Con A provides protection against autoimmune diabetes in nonobese diabetic mice concomitant with phenotypic and morphologic lymphocyte changes.     

Novel considerations on the antibody/autoantigen system in type I (insulin-dependent) diabetes mellitus

Insulin dependent diabetes (IDDM) has an autoimmune pathogenesis. Included is the presence of antibodies to pancreatic islet cells. The first identified were islet cell antibodies (ICA), detected by indirect immunofluorescence, and which react with all cells within islets. Importantly, the autoantibodies are found several years prior to disease and although a pathogenic role for the autoantibodies is unclear, they have become useful markers of prediabetes. A number of studies of twins discordant for IDDM and of first degree relatives of IDDM patients have established that there is an increased risk for disease in individuals who have ICA, especially when ICA levels are high. This high predictive value of ICA decreases in the general population where the incidence of IDDM is lower than in first degree relatives, and both ICA and the disease risk associated with ICA, appear to be influenced by a genetic susceptibility. This has been sustained in a study of patients with endocrine autoimmunity and ICA (Polyendocrine Study) where the predictive value of very high levels of ICA is less than 50% in patients without a first degree relative with IDDM. Hence, there remain a substantial number of patients with ICA who do not develop disease. From these patients, it was demonstrated that ICA include at least two distinct specificities, one of which is beta cell specific and is not associated with a high risk for IDDM.(ABSTRACT TRUNCATED AT 250 WORDS)     

Role of HLA genes in predisposition to develop insulin-dependent diabetes mellitus.

Insulin-dependent diabetes mellitus (IDDM), or type I diabetes, is the end result mainly of a T-cell mediated autoimmune destruction of pancreatic islet beta cells. Genetical and environmental factors are both of importance in the pathogenesis. Genes in the HLA complex seem to be the most important genetical factors. Among Blacks, Caucasoids and Orientals, IDDM susceptibility is associated with some particular combinations of DQA1 and DQB1 genes in cis or trans position. This strongly argues that susceptibility is primarily associated to the corresponding HLA-DQ molecules themselves. However, weaker contributions by other genes in the HLA complex cannot be excluded. Similarly, a dominant protection is strongly associated with some other DQ molecules, in particular HLA-DQ6, in all three ethnic groups. The function of HLA-DQ (and other class II) molecules is to present peptide-fragments of antigens to CD4+ T cells (mainly helper T cells). Thus, the recognition of certain islet beta cell derived peptides by self-reactive CD4+ T cells, may be an initial event in the pathogenesis. The DQ molecules involved in IDDM susceptibility or protection may exert their function either during thymic development of potential self-reactive CD4+ T cells, or by preferential presentation of certain beta-cell derived peptides to CD4+ T cells, or both. The finding that certain DQ molecules as such confer IDDM susceptibility may lead to new methods to prevent IDDM, for example by using blocking peptide analogues.     

Aerosol Insulin Induces Regulatory CD8 γδ T Cells That Prevent Murine Insulin-dependent Diabetes

Cellular immune hyporesponsiveness can be induced by the presentation of soluble protein antigens to mucosal surfaces. Most studies of mucosa-mediated tolerance have used the oral route of antigen delivery and few have examined autoantigens in natural models of autoimmune disease. Insulin is an autoantigen in humans and nonobese diabetic (NOD) mice with insulindependent diabetes mellitus (IDDM). When we administered insulin aerosol to NOD mice after the onset of subclinical disease, pancreatic islet pathology and diabetes incidence were both significantly reduced. Insulin-treated mice had increased circulating antibodies to insulin, absent splenocyte proliferation to the major epitope, insulin B chain amino acids 9–23, which was associated with increased IL-4 and particularly IL-10 secretion, and reduced proliferation to glutamic acid decarboxylase, another islet autoantigen. The ability of splenocytes from insulin-treated mice to suppress the adoptive transfer of diabetes to nondiabetic mice by T cells of diabetic mice was shown to be caused by small numbers of CD8 γδ T cells. These findings reveal a novel mechanism for suppressing cell-mediated autoimmune disease. Induction of regulatory CD8 γδ T cells by aerosol insulin is a therapeutic strategy with implications for the prevention of human IDDM.     

The risk of developing disease for siblings of patients with insulin dependent diabetes mellitus

We analyzed the risk of developing insulin-dependent diabetes mellitus (IDDM) in 411 siblings of patients with IDDM. We found that siblings who had a positive test for antibodies against islet cells (ICA) at the time of diagnosis of the index case had a higher risk of developing IDDM than did those who had negative tests. However, of the ten siblings who developed IDDM, only four were positive at the initial testing. The period of time elapsing from a negative test at screening to a positive test at diagnosis varied but was less than one year in one child. Two of the ten siblings who developed IDDM had negative tests both at screening and at diagnosis. Amongst siblings who were negative at the initial screening, those in whom the index case was diagnosed at a young age had a higher risk of developing IDDM than did those in whom the index case was diagnosed at an older age. The age of the sibling at the time of screening, the sex of the sibling, and a positive family history (one which includes in addition to the index case one or more first-degree relatives with IDDM) did not confer increased risk. Our data suggest that screening for ICA will have to be done often and will have to be continued into adult life in order to identify the 70-80% of diabetics who will be positive at some time in the evolution of their disease.     

Islet-reactive T cells are a marker of preclinical insulin-dependent diabetes.

The destruction of pancreatic islet beta cells in insulin-dependent diabetes mellitus (IDDM) is thought to be T cell mediated. To directly identify islet-reactive T cells in asymptomatic, "preclinical" IDDM individuals with islet cell antibodies (ICA), proliferation of peripheral blood mononuclear cells (PBMC) was measured in the presence of sonicated fetal pig proislets. Stimulation indices (mean +/- SD) for [3H]thymidine uptake by PBMC cultured with sonicated proislets were: preclinical IDDM subjects (n = 22) 6.10 +/- 6.50, recent-onset IDDM subjects (n = 29) 3.66 +/- 3.35, Graves' disease subjects (n = 6) 2.17 +/- 0.93, scleroderma subjects (n = 4) 1.65 +/- 0.19 and normal control subjects (n = 14) 1.63 +/- 0.62. 68% (15/22) of preclinical IDDM, 41% (12/29) of recent-onset IDDM and 17% (1/6) of Graves' disease subjects had T cell reactivity greater than the mean + 2 SD of controls. T cell reactivity to proislets was tissue specific, and greater in magnitude and frequency than to human insulin. The majority of preclinical subjects with ICA greater than 20 Juvenile Diabetes Foundation (JDF) units (12/15, 80%) or antibodies to a 64-kD islet autoantigen (11/15, 73%) had significant T cell reactivity to proislets. ICA greater than 40 JDF units, a strong prognostic marker for progression to clinical IDDM, was an absolute index of T cell reactivity. Overall, the frequency of T cell reactivity in preclinical subjects, 68% (15/22), was comparable to that of ICA greater than 20 JDF units or 64-kD antibodies. Greater T cell reactivity to proislets in preclinical subjects accords with the natural history of autoimmune beta cell destruction. The direct assay of islet-reactive T cells in peripheral blood may have prognostic significance for the development of clinical IDDM and should facilitate identification of the primary target autoantigen(s).     

Islet cell autoantigen 69 kD (ICA69). Molecular cloning and characterization of a novel diabetes-associated autoantigen.

We have identified a novel 69-kD peptide autoantigen (ICA69) associated with insulin-dependent diabetes mellitus (IDDM) by screening a human islet lambda gt11 cDNA expression library with cytoplasmic islet cell antibody positive sera from relatives of IDDM patients who progressed to the overt disease. The deduced open reading frame of the ICA69 cDNA predicts a 483-amino acid protein. ICA69 shows no nucleotide or amino acid sequence relation to any known sequence in GenBank, except for two short regions of similarity with BSA. The ICA69 cDNA probe hybridizes with a 2-kb mRNA in poly(A+) RNA from human pancreas, brain, heart, thyroid, and kidney, but not with skeletal muscle, placenta, spleen, or ovary. Expression of ICA69 was also detected in beta cells and cell lines, as well as in tumoral tissue of islet cell origin. The native ICA69 molecule migrates to 69 kD in SDS-PAGE as detected with specific antibodies. Serum samples from relatives of IDDM patients specifically reacted with affinity-purified recombinant ICA69 on Western blotting. The structural gene for ICA69 was designated ICA1. A homologue in the mouse, designated Ica-1 was mapped to the proximal end of chromosome 6 (within 6 cM of the Met protooncogene). ICA69 adds a novel autoantigen to the family of identified islet target molecules, and by the manner of its identification and characterization large amounts of antigen are available for development of quantitative, convenient predictive assays for autoantibodies and analysis of the role of this molecule in diabetes autoimmunity, as well as its physiologic function.     

Novel Considerations on the Antibody/Autoantigen System in Type I (insulin-dependent) Diabetes Mellitus

Insulin dependent diabetes (IDDM) has an autoimmune pathogenesis. Included is the presence of antibodies to pancreatic islet cells. The first identified were islet cell antibodies (ICA), detected by indirect immunofluorescence, and which react with all cells within islets. Importantly, the autoantibodies are found several years prior to disease and although a pathogenic role for the autoantibodies is unclear, they have become useful markers of prediabetes. A number of studies of twins discordant for IDDM and of first degree relatives of IDDM patients have established that there is an increased risk for disease in individuals who have ICA, especially when ICA levels are high. This high predictive value of ICA decreases in the general population where the incidence of IDDM is lower than in first degree relatives, and both ICA and the disease risk associated with ICA, appear to be influenced by a genetic susceptibility. This has been substantiated in a study of patients with endocrine autoimmunity and ICA (Polyendocrine Study) where the predictive value of very high levels of ICA is less than 50% in patients without a first degree relative with IDDM. Hence, there remain a substantial number of patients with ICA who do not develop disease. From these patients, it was demonstrated that ICA include at least two distinct specificities, one of which is beta cell specific and is not associated with a high risk for IDDM.

These data, and an increasing list of new autoantibodies in IDDM, have increased the search for the relevant autoantigens. That of classic ICA is suggested to be a sialoganglioside, and a number of protein autoantigens have been suggested as other potential autoantigens. Of particular importance has been the identification of glutamic acid decarboxylase (GAD), the biosynthesizing enzyme of the neurotransmitter gamma amino butyric acid, as the autoantigen corresponding to the 64K autoantibodies found in the majority of newly diagnosed IDDM patients. Despite the identification of GAD, specific assays developed so far have not detected anti GAD antibodies at high frequencies in newly diagnosed patients. Like ICA, it appears that there may be distinct specificities of autoantibodies to GAD and associated products. Enzyme digestion of the autoantigen yields 50K, 40K and 37K fragments which appear to be derived from distinct polypeptide chains. Patients may have autoantibodies to either the 50K fragment or the 40/37K fragment or all fragments. Importantly, studies in twins and in the polyendocrine patients indicate that autoantibodies to the 37K fragment are more strongly associated with the progression to disease.

In addition to these autoantigens, autoantibodies are detected against the hormone insulin and its precursor proinsulin in up to 40% of newly diagnosed patients. Heat shock protein 65, carboxypeptidase H and glucose transporter have also been reported as autoantigens relevant to IDDM. It is now clear that the autoimmune response associated with IDDM is heterogeneous and against several islet antigens. The search will continue to determine which of these is important in the pathogenesis and which will provide effective markers for prediction which will eventually allow safe intervention therapy for the prevention of IDDM.     

Detection of pancreatic islet 64,000 M(r) autoantigens in insulin-dependent diabetes distinct from glutamate decarboxylase.

Patients with insulin-dependent diabetes (IDDM) possess antibodies to islet proteins of M(r)-64,000. Potential autoantigens of this M(r) include glutamate decarboxylase (GAD) and 65 kD heat shock protein. We have detected two distinct antibody specificities in IDDM that bind 50,000 M(r) or 37,000/40,000 M(r) proteolytic fragments of 64,000 M(r) proteins. In this study, we investigated relationships of these proteolytic fragments to GAD and heat shock proteins. Polyclonal antibodies to GAD bound 50,000 M(r) fragments of islet antigen. Recombinant GAD65, but not GAD67, blocked binding to this antigen, suggesting that 50,000 M(r) fragments are derived from islet GAD65. In contrast, GAD antibodies did not recognize 37,000/40,000 M(r) fragments, and neither GAD isoforms blocked autoantibody binding to precursors of these fragments. The 37,000/40,000 M(r) fragments, but not the 50,000 M(r) fragments, were detected after trypsin treatment of immunoprecipitates from insulinoma cells that lacked expression of major GAD isoforms. Antibodies in IDDM did not bind native or trypsinized islet heat shock proteins. Thus, IDDM patients possess antibodies to GAD, but also distinct antibodies to a 64,000 M(r) protein that is not related to known GAD isoforms or heat shock proteins.     

Stable expression of manganese superoxide dismutase (MnSOD) in insulinoma cells prevents IL-1beta- induced cytotoxicity and reduces nitric oxide production.

The fact that insulin-producing islet beta-cells are susceptible to the cytotoxic effects of inflammatory cytokines represents a potential hinderance to the use of such cells for transplantation therapy of insulin-dependent diabetes mellitus (IDDM). In the current study, we show that IL-1beta induces destruction of INS-1 insulinoma cells, while having no effect on a second insulinoma cell line RIN1046-38 and its engineered derivatives, and that this difference is correlated with a higher level of expression of manganese superoxide dismutase (MnSOD) in the latter cells. Stable overexpression of MnSOD in INS-1 cells provides complete protection against IL-1beta-mediated cytotoxicity, and also results in markedly reduced killing when such cells are exposed to conditioned media from activated human or rat PBMC. Further, overexpression of MnSOD in either RIN- or INS-1-derived lines results in a sharp reduction in IL-1beta-induced nitric oxide (NO) production, a finding that correlates with reduced levels of the inducible form of nitric oxide synthase (iNOS). Treatment of INS-1 cells with L-NMMA, an inhibitor of iNOS, provides the same degree of protection against IL-1beta or supernatants from LPS-activated rat PBMC as MnSOD overexpression, supporting the idea that MnSOD protects INS-1 cells by interfering with the normal IL-1beta-mediated increase in iNOS. Because NO and its derivatives have been implicated as critical mediators of beta-cell destruction in IDDM, we conclude that well regulated insulinoma cell lines engineered for MnSOD overexpression may be an attractive alternative to isolated islets as vehicles for insulin replacement in autoimmune diabetes.     

T-cell assays to determine disease activity and clinical efficacy of immune therapy in type 1 diabetes

Type 1 (insulin-dependent) diabetes mellitus results from a T cell-mediated autoimmune destruction of the pancreatic beta cells in genetically predisposed individuals. Therapies directed against T cells have been demonstrated to halt the disease process and prevent recurrent beta-cell destruction after islet transplantation. Less is known about the nature and function of these T cells, the cause of the loss of tolerance to islet autoantigens, why the immune system apparently fails to suppress autoreactivity, and whether (or which) autoantigen(s) are critically involved in the initiation or progression of disease. Autoreactive T cells have proven to be valuable targets to study pathogenic or diabetes-related processes. Measuring T-cell autoreactivity also provided critical information to determine the fate of islet allografts transplanted to type 1 diabetic patients. Furthermore, these studies have provided proof of operational immunologic tolerance to islet allografts as well as valuable information to improve and customize immunosuppressive therapy. Currently, technologies to detect T-cell auto- and alloreactivity in type 1 diabetic recipients of islet allografts are applied to monitor islet allograft survival in relation with various immunosuppressive therapies and to guide tapering of these therapies after successful restoration of insulin production. Although it is generally appreciated that studies on cellular auto- and alloimmunity are hampered by the complex nature of such immune responses and the required technical and physical skills, it has been a worthwhile quest to unravel the role of T cells in the pathogenesis of type 1 diabetes and islet allograft destruction.     

Role of HLA Genes in Predisposition to Develop Insulin-dependent Diabetes Mellitus

Insulin-dependent diabetes mellitus (IDDM), or type I diabetes, is the end result mainly of a T-cell mediated autoimmune destruction of pancreatic islet β cells. Genetical and environmental factors are both of importance in the pathogenesis. Genes in the HLA complex seem to be the most important genetical factors. Among Blacks, Caucasoids and Orientals, IDDM susceptibility is associated with some particular combinations of DQA1 and DQB1 genes in cis or trans position. This strongly argues that susceptibility is primarily associated to the corresponding HLA-DQ molecules themselves. However, weaker contributions by other genes in the HLA complex cannot be excluded. Similarly, a dominant protection is strongly associated with some other DQ molecules, in particular HLA-DQ6, in all three ethnic groups.

The function of HLA-DQ (and other class II) molecules is to present peptide-fragments of antigens to CD4⁺ T cells (mainly helper T cells). Thus, the recognition of certain islet β cell derived peptides by self-reactive CD4⁺ T cells, may be an initial event in the pathogenesis. The DQ molecules involved in IDDM susceptibility or protection may exert their function either during thymic development of potential self-reactive CD4⁺ T cells, or by preferential presentation of certain β–cell derived peptides to CD4⁺ T cells, or both. The finding that certain DQ molecules as such confer IDDM susceptibility may lead to new methods to prevent IDDM, for example by using blocking peptide analogues.     

Development of insulinoma cells as therapy in insulin-dependent diabetes mellitus]

In healthy persons insulin secreting beta-cells of the pancreas regulate blood glucose levels within a narrow physiological range. Since the detection of insulin in 1922 by Banting and Best, subcutaneous insulin replacement has remained the sole treatment modality for insulin-dependent diabetes mellitus (IDDM). However, even trained patients undergoing intensive insulin therapy fail to achieve normal function of the pancreatic beta-cells. One approach to solve this problem is pancreas and islet cell transplantation. Because of technical problems, limited number of transplantable organs and toxicity of immunosuppressive therapy, both are still in an experimental state. An alternative approach is the development of genetically modified insulin secreting cell lines for replacement of islet cells. So far, experiments support the expectation to develop genetically manipulated cell lines who imitate the function of islet beta-cells and are protected from the immune response. The ultimate goal is the development of an engineered human beta-cell line and, after animal experiments, to use it for treatment of patients with IDDM.     

Effects of low-dose cyclosporine prophylaxis in nonobese diabetic mice

Among female nonobese diabetic mice, ketotic insulin-dependent diabetes mellitus (IDDM) develops spontaneously in 80% between 12 and 26 weeks of age. This condition resembles human type I diabetes. IDDM developed in 0 of 11 (0%) mice prophylactically treated with 10 mg of cyclosporine A (CyA) per kg s.c. every 4th day from 8 to 26 weeks of age; 8 of 10 (80%) of sex- and age-matched controls developed IDDM; 2 of 8 (25%) followed up to 5 months beyond the time of drug administration developed IDDM. The distribution of specific radioactivity ([3H]CyA) was used to calculate the concentrations of CyA in serum, blood cells and various organs. Serum values of CyA produced by radioimmunoassay were higher than those estimated by the [3H]CyA method. Pancreata of CyA-treated mice were histologically normal. Pancreata of control mice showed lymphocytic infiltration of the islets of Langerhans. Neither hepatotoxicity nor nephrotoxicity assessed by biochemical and histological data was detectable in CyA-treated mice. The insulin secretory capacity of trypan blue viable functional pancreatic islets isolated post-treatment; was significantly lower in controls than in CyA-treated mice; islet content of insulin was not statistically different between controls and CyA-treated mice. We conclude that low nontoxic doses of CyA abrogate completely the development of diabetes in the female nonobese diabetic mouse and abolish lymphocytic infiltration of the islets of Langerhans against which there is autoimmunity. The effect of CyA persists well past the duration of therapy.     

Vascular endothelial cell antibodies in diabetic patients. Association with diabetic retinopathy.

OBJECTIVE--To determine the incidence of antiendothelial cell antibodies in diabetic patients with and without retinopathy. RESEARCH DESIGN AND METHODS--The study consisted of 70 insulin-dependent diabetic (IDDM) subjects, 36 non-insulin-dependent diabetic (NIDDM) subjects, and 40 nondiabetic control subjects. Blood samples were obtained from diabetic patients and control subjects and patients with background and proliferative retinopathy were identified. RESULTS--Vascular endothelial cell (VEC) antibodies were examined in the sera of 36 NIDDM subjects, 70 IDDM subjects, and 40 nondiabetic control subjects by indirect immunofluorescence. VEC antibodies were present in 5 of 40 (12%) control subjects, 7 of 23 (30%) newly diagnosed IDDM patients, 6 of 17 (35%) IDDM patients without retinopathy, 12 of 18 (67%) IDDM patients with background retinopathy (P less than 0.05), and 9 of 12 (75%) IDDM patients with proliferative retinopathy (P less than 0.01). Three of 13 (23%) NIDDM patients with retinopathy and 6 of 23 (26%) without retinopathy were VEC antibody positive. No associations were observed between the presence of VEC antibodies and either the quality of glycemic control or the duration of diabetes. A significant association between VEC antibodies and large-vessel disease was found in IDDM patients with retinopathy (P less than 0.05). CONCLUSIONS--Antibodies directed against vascular endothelial cells may play a role in the development of microvascular, and possibly macrovascular, disease in diabetes.     

抗氧化微量营养素对糖尿病小鼠胰岛细胞形态影响

目的　研究抗氧化微量营养素对糖尿病小鼠胰岛细胞形态的影响。方法　使用链脲佐菌素 (STZ)制备糖尿病小鼠模型 ,经每日灌胃补充硒 (Se)、钒 (V)、铬 (Cr)、维生素E(VE)等抗氧化微量营养素 ,每周监测血糖和体重 ,补充 7周后处死动物 ,石蜡包埋胰腺组织 ,制备HE染色切片及免疫组织化学检测。结果　补充抗氧化微量营养素可明显降低糖尿病小鼠血糖水平 ,改善胰岛形态结构。结论　抗氧化微量营养素可调节糖尿病小鼠糖代谢水平 ,对胰岛 β细胞有一定的保护作用。