Islet cell autoantigens in insulin-dependent diabetes.

A burgeoning number of antigenic targets of the islet cell autoimmunity in IDD have been identified, and more can be anticipated through improved methods for their identification. The challenge for those investigating the pathogenesis of IDD will be to assign the relative importance of these antigens to the development of the disease, and to resolve whether there is a dominant primary immunologic event that is followed by a series of secondary immunizations to a variety of normally sequestered islet cell antigens in the sequence of pathogenic events that culminate in IDD. One interesting observation that may have potential pathogenic implications is the observation that of all islet cell autoantigens described, only two (i.e., 64 kD/GAD, 38 kD) are reactive in their native configurations, implying that recognition of conformational epitopes is most important. This property argues for primary immunizing agents rather than secondary ones after release of denatured antigens and antigenic recognition through their epitopes. Given the complex and multiple physiological functions of islet cells and the continuous variation in their activity, it is reasonable to speculate that the speed of the progression to IDD could vary between individuals with respect to their insulin needs and the relative activities of their islets. Activated islets may express autoantigens that have only limited expression in quiescent islets. The often times striking variation in the severity of insulitis seen in different islets of a single pancreas may be explained by the level of activity of individual islets. Furthermore, disparity in HLA-DR/DQ associations with disease may involve differences in the immunological recognition of autoantigens. Whereas there is still much to learn, it is clear that disease predictability and disease intervention studies have been enhanced through the identification of the islet cell autoantigens in IDD.     

Autoimmunity to two forms of glutamate decarboxylase in insulin-dependent diabetes mellitus.

Insulin-dependent diabetes mellitus (IDDM) is thought to result from the autoimmune destruction of the insulin-producing beta cells of the pancreas. Years before IDDM symptoms appear, we can detect autoantibodies to one or both forms of glutamate decarboxylase (GAD65 and GAD67), synthesized from their respective cDNAs in a bacterial expression system. Individual IDDM sera show distinctive profiles of epitope recognition, suggesting different humoral immune responses. Although the level of GAD autoantibodies generally decline after IDDM onset, patients with IDDM-associated neuropathies have high levels of antibodies to GAD, years after the appearance of clinical IDDM. We note a striking sequence similarity between the two GADs and Coxsackievirus, a virus that has been associated with IDDM both in humans and in experimental animals. This similarity suggests that molecular mimicry may play a role in the pathogenesis of IDDM.     

Islet cell cytoplasmic autoantibody reactivity to glutamate decarboxylase in insulin-dependent diabetes.

Individuals with or at risk for insulin-dependent diabetes (IDD) frequently have autoantibodies against an islet cell cytoplasmic (ICA) antigen thought to be a sialoglycolipid. However, we now report that preabsorption of ICA-positive sera with recombinant glutamate decarboxylase (human GAD 65 and/or GAD 67) reduced or blocked the ICA reactivity of 5/18 (27%) new-onset IDD patients and 7/18 (39%) prediabetics. Interestingly, nondiabetic subjects with ICA of > or = 5 yr in duration had GAD-reactive ICA significantly more often (16/24, 67%, P < 0.04) than the diabetic groups. ICA reactivity to GAD was not related to serum ICA titer nor the age of the individual, and in all cases tested was blocked by GAD 65 or GAD 67 with equivalent efficiency. The ICA observed in 21/25 (84%) IDD patients with ICA long after clinical onset of disease (9-42 yr) was reactive to GAD. A natural history analysis of three individuals showed conversions from ICA which was reactive to GAD to a non-GAD-reactive ICA nearer to their clinical onsets of IDD. This study further defines the autoantigens reactive to ICA, and suggests that, whereas ICA that are not reactive to GAD may identify an advanced and more prognostic lesion, GAD-reactive ICA may typify the early or inductive lesion that may or may not progress to clinically significant beta cell injury.     

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.     

Cellular immunity to a determinant common to glutamate decarboxylase and coxsackie virus in insulin-dependent diabetes.

Insulin-dependent diabetes (IDD) results from the autoimmune destruction of the insulin-producing pancreatic beta cells. Autoreactive T-lymphocytes are thought to play a pivotal role in the pathogenesis of IDD; however, the target antigens of these cells, as well as the inductive events in the disease, are unclear. PBMC in persons with or at increased risk for IDD show elevated reactivity to the beta cell enzyme glutamate decarboxylase (GAD). To identify the T-lymphocyte-reactive determinants of GAD, an overlapping set of synthetic peptides was used to stimulate the PBMC from these individuals, PBMC responsiveness to GAD peptides was not restricted to those with IDD, and a number of peptides elicited responses in PBMC. However, the major determinant of GAD recognized by persons at increased risk for IDD was amino acids 247-279, a region which has significant sequence similarity to the P2-C protein of Coxsackie B virus (47% of 15 increased risk [islet cell autoantibody-positive relatives]; 25% of 16 newly diagnosed IDD patients; and 0% of 13 healthy control subjects). Responses to tetanus and insulin antigens were not different between the study groups. In addition, PBMC from individuals responding to GAD peptides within 247-279 also responded to a Coxsackie viral peptide (i.e., P2-C amino acids 32-47), an observation supporting potential molecular mimicry in this immune response. Although the role of environmental agents in the pathogenesis of the disease remains unclear, these cellular immunological findings support the epidemiological evidence suggesting an inductive role for enteroviruses like Coxsackie B in the autoimmunity underlying IDD.     

Nasal administration of glutamate decarboxylase (GAD65) peptides induces Th2 responses and prevents murine insulin-dependent diabetes

We previously demonstrated that a spontaneous Th1 response against glutamate decarboxylase (GAD65) arises in NOD mice at four weeks in age and subsequently T cell autoimmunity spreads both intramolecularly and intermolecularly. Induction of passive tolerance to GAD65, through inactivation of reactive T cells before the onset of autoimmunity, prevented determinant spreading and the development of insulin- dependent diabetes mellitus (IDDM). Here, we examined whether an alternative strategy, designed to induce active tolerance via the engagement of Th2 immune responses to GAD65, before the spontaneous onset of autoimmunity, could inhibit the cascade of Th1 responses that lead to IDDM. We observed that a single intranasal administration of GAD65 peptides to 2-3-wk-old NOD mice induced high levels of IgG1 antibodies to GAD65. GAD65 peptide treated mice displayed greatly reduced IFN gamma responses and increased IL-5 responses to GAD65, confirming the diversion of the spontaneous GAD65 Th1 response toward a Th2 phenotype. Consistent with the induction of an active tolerance mechanism, splenic CD4+ (but not CD8+) T cells from GAD65 peptide- treated mice, inhibited the adoptive transfer of IDDM to NOD-scid/scid mice. This active mechanism not only inhibited the development of proliferative T cell responses to GAD65, it also limited the expansion of autoreactive T cell responses to other beta cell antigens (i.e., determinant spreading). Finally, GAD65 peptide treatment reduced insulitis and long-term IDDM incidence. Collectively, these data suggest that the nasal administration of GAD65 peptides induces a Th2 cell response that inhibits the spontaneous development of autoreactive Th1 responses and the progression of beta cell autoimmunity in NOD mice.     

Prevalence of autoantibodies to the 65- and 67-kD isoforms of glutamate decarboxylase in insulin-dependent diabetes mellitus.

We investigated the presence of autoantibodies to baculovirus-expressed human recombinant 65- and 67-kD isoforms of glutamate decarboxylase (GAD65 and GAD67) in insulin-dependent diabetes mellitus (IDDM). In the immunoprecipitation test using [35S]methionine-labeled GADs antibodies to GAD65 were detected in 13/15 (87%) islet cell antibody (ICA)-positive and in 1/35 (2.9%) ICA-negative first-degree relatives of patients with IDDM, in 6/11 (54.5%) ICA-positive nondiabetic schoolchildren, and in 35/50 (70%) patients with newly diagnosed IDDM. GAD67 antibodies were positive only in five (33%) of the ICA-positive relatives (P < 0.05) and in nine (18%) IDDM patients at onset (P < 0.00001). After onset of IDDM antibodies to GAD65 and GAD67 declined but were still positive in 25 and 9.4% of subjects with long-standing IDDM (> 10 yr). In all study groups antibodies to GAD67 were only detected in GAD65 antibody-positive sera. An immunotrapping enzyme activity assay for GAD65 antibodies was positive in 64/75 (85.3%) of sera that were GAD antibody positive in the immunoprecipitation test (r = 0.870, P < 0.0001). In two (2.7%) sera GAD65 antibodies that block GAD enzyme activity were found. Our data suggest that antibodies to GAD65 but not to GAD67 represent sensitive markers for preclinical and overt IDDM. The immunotrapping assay here described represents a valuable technique for specific and sensitive screening for GAD antibodies.     

Metabolic effects of successful intraportal islet transplantation in insulin-dependent diabetes mellitus.

The intraportal injection of human pancreatic islets has been indicated as a possible alternative to the pancreas transplant in insulin-dependent diabetic patients. Aim of the present work was to study the effect of intraportal injection of purified human islets on: (a) the basal hepatic glucose production; (b) the whole body glucose homeostasis and insulin action; and (c) the regulation of insulin secretion in insulin-dependent diabetes mellitus patients bearing a kidney transplant. 15 recipients of purified islets from cadaver donors (intraportal injection) were studied by means of the infusion of labeled glucose to quantify the hepatic glucose production. Islet transplanted patients were subdivided in two groups based on graft function and underwent: (a) a 120-min euglycemic insulin infusion (1 mU/kg/min) to assess insulin action; (b) a 120-min glucose infusion (+75 mg/di) to study the pattern of insulin secretion. Seven patients with chronic uveitis on the same immunosuppressive therapy as grafted patients, twelve healthy volunteers, and seven insulin-dependent diabetic patients with combined pancreas and kidney transplantation were also studied as control groups. Islet transplanted patients have: (a) a higher basal hepatic glucose production (HGP: 5.1 +/- 1.4 mg/kg/ min; P < 0.05 with respect to all other groups) if without graft function, and a normal HGP (2.4 +/- 0.2 mg/kg/min) with a functioning graft; (b) a defective tissue glucose disposal (3.9 +/- 0.5 mg/kg/min in patients without islet function and 5.3 +/- 0.4 mg/kg/min in patients with islet function) with respect to normals (P < 0.01 for both comparisons); (c) a blunted first phase insulin peak and a similar second phase secretion with respect to controls. In conclusion, in spite of the persistence of an abnormal pattern of insulin secretion, successful intraportal islet graft normalizes the basal HGP and improves total tissue glucose disposal in insulin-dependent diabetes mellitus.     

Elimination of islet cell antibodies and glutamic acid decarboxylase antibodies II in a patient with newly diagnosed insulin-dependent diabetes mellitus

Islet cell antibodies and glutamic acid decarboxylase II (GAD II) antibodies have been discussed in the autoimmune pathogenesis of insulin-dependent diabetes mellitus (IDDM). Hence, immunosuppressants, intravenous immunoglobulins, and plasmapheresis have been used in an effort to modulate autoimmune activity and thereby prevent the destruction of pancreatic β-cells. We describe the autoantibody (islet cell antibody and GAD II) kinetics and clinical course in a patient with newly diagnosed IDDM treated with a specific immunoglobulin apheresis technique. Five days after the initial diagnosis a 37-year-old patient with IDDM underwent a series of seven immunoglobulin aphereses. Immunoglobulin (IgG, IgA, IgM), islet cell antibody, GAD II, and C-peptide concentrations were monitored for a time course of 74 days. Daily insulin requirements were recorded. One single immunoglobulin apheresis decreased IgG by 66.2 ± 9.1%, IgA by 66.8 ± 8.7%, and IgM by 57.7 ± 12.9%. GAD II antibodies were reduced by 61.9 ± 12.4%. The islet cell antibody titer declined from 1:32 to 1:4 after the treatment series. There were no relevant changes in the safety parameters determined nor were there any clinical side effects. The efficient decrease in islet cell antibodies and glutamic acid decarboxylase II antibodies in a patient with IDDM encourages further investigations into the impact of this treatment on the clinical course of this autoimmune disorder. J. Clin. Apheresis 12:196–199, 1997. © 1997 Wiley-Liss, Inc.     

Relationship of the 37,000- and 40,000-M(r) tryptic fragments of islet antigens in insulin-dependent diabetes to the protein tyrosine phosphatase-like molecule IA-2 (ICA512).

Sera from patients with insulin-dependent diabetes immunoprecipitate 64,000-M(r) proteins, distinct from glutamate decarboxylase, that are cleaved to 37,000- and 40,000-M(r) fragments by trypsin. We investigated possible relationships between 37,000- or 40,000-M(r) fragments of antigen and the tyrosine phosphatase-like protein, IA-2 (ICA512). Antibodies from nondiabetic relatives bound differentially to 37,000- and 40,000-M(r) fragments indicating presence of distinct epitopes. Precursors of these fragments could be separated on immobilized lectins, suggesting different carbohydrate content. Levels of antibodies to 40,000-M(r) fragments were strongly associated with those to the intracellular domain of IA-2. Recombinant intracellular domain of IA-2 blocked binding of antibodies to 40,000-M(r) fragments expressed by insulinoma cells and partially blocked binding to 37,000-M(r) fragments. Furthermore, trypsinization of recombinant intracellular domain of IA-2 generated proteolytic fragments of identical M(r) to the 40,000-M(r) fragments of insulinoma antigen; 37,000-M(r) fragments were not generated. Thus, 40,000-M(r) fragments of islet autoantigen are derived from a protein similar or identical to the tyrosine phosphatase-like molecule, IA-2. The 37,000-M(r) fragments are derived from a different, although related, protein.     

Protection of NOD mice from type 1 diabetes after oral inoculation with vaccinia viruses expressing adjuvanted islet autoantigens

Oral administration of autoantigens and allergens can delay or suppress clinical disease in experimental autoimmune and allergic disorders. However, repeated feeding of large amounts of the tolerogens is required over long periods and is only partially effective in animals systemically sensitized to the ingested antigen. Enhanced suppression of type 1 autoimmune diabetes insulitis and hyperglycemia was demonstrated in both naive and immune animals following oral inoculation with plant-based antigens coupled to the cholera toxin B subunit (CTB). Thus, plant-synthesized antigens linked to the CTB adjuvant, can enhance suppression of inflammatory TH1 lymphocyte-mediated autoreactivity in both naive and immune animals. To stimulate adjuvant-autoantigen fusion protein biosynthesis in the gut mucosae, the authors evaluated oral inoculation of juvenile non-obese diabetic (NOD) mice with recombinant vaccinia virus (rVV) expressing fusion genes encoding CTB linked to the pancreatic islet autoantigens proinsulin (INS) and a 55-kDa C-terminal peptide from glutamate decarboxylase (GAD55). Hyperglycemia in both rVV-CTB:: INS and rVV-CTB:: GAD inoculated mice was substantially reduced in comparison with the uninoculated mouse control. Oral inoculation with rVV carrying the CTB::INS fusion gene generated a significant reduction in insulitis. An increase in IgG1 in comparison with IgG2c antibody isotype titers in rVV-CTB::INS infected mice suggested possible activation of autoantigen specific Th2 lymphocytes. The experimental results demonstrate feasibility of using vaccinia virus oral delivery of adjuvanted autoantigens to the mucosae of prediabetic mice for suppression and therapy of type 1 autoimmune diabetes.     

Fusion proteins for combined analysis of autoantibodies to the 65-kDa isoform of glutamic acid decarboxylase and islet antigen-2 in insulin-dependent diabetes mellitus

BACKGROUND: Prediction, risk assessment, and diagnosis of autoimmune diseases often rely on detection of autoantibodies directed to multiple target antigens, such as the 65-kDa isoform of glutamic acid decarboxylase (GAD65-abs) and the tyrosine phosphatase-like protein islet antigen-2 (IA2-abs), the two major subspecificities of islet cell antibodies (ICAs) associated with insulin-dependent diabetes mellitus. We hypothesized that a combination of autoantigens in a fusion protein unifying the important immunodominant epitopes could provide an efficient target for cost-effective, one-step screening of sera. METHODS: Chimeric proteins composed of GAD65 and IA2 residues were constructed, analyzed for their immune reactivity with monoclonal antibodies and sera, and used in a diagnostic assay with (35)S-labeled protein as antigen. RESULTS: Length and order of GAD65 and IA2 sequences were critical for conservation of the conformational epitopes in the fusion protein. Among four chimera tested, only IA2((606-979))/GAD65((1-585)) retained wild-type-like folding of GAD65 and IA2 domains and yielded a stable protein after baculovirus expression. Reactivity of GAD65 antibody- and IA2 antibody-positive sera from patients newly diagnosed with insulin-dependent diabetes mellitus, from ICA-positive prediabetics, and from ICA-positive first-degree relatives demonstrated conservation of the relevant autoreactive epitopes. The assay based on the in vitro translated fusion antigen had a sensitivity and specificity identical to those for detection of GAD65- and IA2-abs based on the two separate GAD65 and IA2 proteins. CONCLUSIONS: Autoantigens such as GAD65 and IA2 can be combined successfully in a fusion protein of similar immune reactivity. This allows simultaneous detection of GAD65- and IA2-abs in a one-step screening assay and cost-effective identification of positive individuals at risk of diabetes or at onset of disease.     

1型糖尿病胰岛自身抗体与胰岛功能的关系

目的分析不同种类、不同数量胰岛自身抗体阳性的1型糖尿病(T1DM)患者临床特征及胰岛功能。方法收集患者一般信息,行标准馒头餐试验(MMTT)、酶联免疫吸附试验(ELISA)检测胰岛细胞抗体(ICA)、胰岛素抗体(IAA)、谷氨酸脱羧酶抗体(GADA)和蛋白酪氨酸磷酸酶抗体(IA-2A),用SPSS 22.0软件对不同胰岛自身抗体阳性患者的临床特征及胰岛功能进行分析。结果 (1)本试验共纳入T1DM患者572例(男322例,女250例),平均年龄36岁(4~84岁)。四种胰岛自身抗体的阳性率分别为GADA 57%(326/572),IA-2A 27.4%(157/572),ICA18.4%(105/572),IAA 23.3%(13/572),且GADA阳性率显著高于其他三种抗体(P<0.05)。(2)联合检测GADA、ICA、IA-2A三种抗体,抗体阳性数目越多,BMI越小,病程越短,糖化血红蛋白越高,空腹及餐后120 min C肽越低,C肽曲线下面积(AUC)越小,各组间差异均存在统计学意义(P<0.05)。(3)空腹C肽在单一IA-2A阳性组最低,餐后120 min C肽、AUC在单一ICA阳性组最低,但三个单一抗体阳性组间差异无统计学意义(P>0.05);病程、年龄及BMI在IA-2A阳性组最低,三个单一抗体阳性组差异无统计学意义(P>0.05)。(4)GADA+IA-2A双阳性组空腹及餐后120 min C肽、AUC均最低,年龄、病程、BMI较低,与抗体阴性组差异有统计学意义,但与GADA+ICA阳性及ICA+IA-2A阳性组差异无统计学意义(P>0.05)。结论抗体阳性数目越多,病程越短,胰岛功能越差;单独或合并不同抗体阳性的患者临床特征和胰岛功能分析对临床早期干预有指导意义。     

非胰岛素依赖糖尿病自身抗体和胰岛细胞功能的关系

目的探讨非胰岛素依赖糖尿病(NIDDM)三种主要自身抗体与胰岛细胞分泌功能之间的关系.方法对110例正常者和175例初诊为NIDDM的患者测定空腹及口服葡萄糖75克后2小时静脉血浆葡萄糖,胰岛素,C肽,胰高血糖素(分别简写为FPG、2hPG、Fins、2hIns、FCP、2hCP、FGCG、2hGCG),并计算其胰岛素敏感指数(ISI).同时,测定NIDDM组血清中谷氨酸脱羧酶抗体(GAD-Ab)、胰岛素自身抗体(IAA)和胰岛细胞抗体(ICA),根据三种自身抗体再把NIDDM组分为全阴性、全阳性、GAD-Ab阳性、IAA阳性、ICA阳性5个亚组.观察初诊NIDDM组自身抗体的阳性率和自身抗体与胰岛细胞功能的关系.结果(1)NIDDM组GAD-Ab、IAA、ICA阳性率分别为29.1%(51/175)、31.4%(55/175)、18.3%(32/175).(2)NIDDM组FCP、FGCG比对照组分泌增多,ISI降低(P分别为0.008、＜0.001、＜0.001).(3)三种抗体全阳性、GAD-Ab阳性、IAA阳性、ICA阳性亚组的FCP均低于全阴性亚组(P＜0.01).其中全阳性亚组、GAD阳性和ICA阳性亚组的FGCG高于全阴性亚组(P分别为0.007、0.047、0.012).结论在初诊的NIDDM患者中自身抗体阳性预示其胰岛B细胞功能受损.     

非胰岛素依赖糖尿病自身抗体和胰岛细胞功能的关系

目的探讨非胰岛素依赖糖尿病(NIDDM)三种主要自身抗体与胰岛细胞分泌功能之间的关系。方法对110例正常者和175例初诊为NIDDM的患者测定空腹及口服葡萄糖75克后2小时静脉血浆葡萄糖,胰岛素,C肽,胰高血糖素(分别简写为FPG、2hPG、Fins、2hIns、FCP、2hCP、FGCG、2hGCG),并计算其胰岛素敏感指数(ISI)。同时,测定NIDDM组血清中谷氨酸脱羧酶抗体(GAD-Ab)、胰岛素自身抗体(IAA)和胰岛细胞抗体(ICA),根据三种自身抗体再把NIDDM组分为全阴性、全阳性、GAD-Ab阳性、IAA阳性、ICA阳性5个亚组。观察初诊NIDDM组自身抗体的阳性率和自身抗体与胰岛细胞功能的关系。结果(1)NIDDM组GAD-Ab、IAA、ICA阳性率分别为29.1%(51/175)、31.4%(55/175)、18.3%(32/175)。(2)NIDDM组FCP、FGCG比对照组分泌增多,ISI降低(P分别为0.008、<0.001、<0.001)。(3)三种抗体全阳性、GAD-Ab阳性、IAA阳性、ICA阳性亚组的FCP均低于全阴性亚组(P<0.01)。其中全阳性亚组、GAD阳性和ICA阳性亚组的FGCG高于全阴性亚组(P分别为0.007、0.047、0.012)。结论在初诊的NIDDM患者中自身抗体阳性预示其胰岛B细胞功能受损。     

Collagen binding activity in sera of patients with insulin-dependent (type 1) and non insulin-dependent (type 2) diabetes mellitus

An increase in the capacity of serum IgG to bind to native type IV collagen was observed in patients with both insulin-dependent and non insulin-dependent diabetes mellitus. This increased binding seems to be due to circulating immune complexes in the majority of the cases and to autoantibodies in some. The increased collagen binding activity was associated in postpubertal patients with the presence of diabetic microangiopathy, suggesting a pathogenetic role.     

Noninvasive imaging of pancreatic islet inflammation in type 1A diabetes patients

Type 1A diabetes (T1D) is an autoimmune disease characterized by leukocyte infiltration of the pancreatic islets of Langerhans. A major impediment to advances in understanding, preventing, and curing T1D has been the inability to "see" the disease initiate, progress, or regress, especially during the occult phase. Here, we report the development of a noninvasive method to visualize T1D at the target organ level in patients with active insulitis. Specifically, we visualized islet inflammation, manifest by microvascular changes and monocyte/macrophage recruitment and activation, using magnetic resonance imaging of magnetic nanoparticles (MNPs). As a proof of principle for this approach, imaging of infused ferumoxtran-10 nanoparticles permitted effective visualization of the pancreas and distinction of recent-onset diabetes patients from nondiabetic controls. The observation that MNPs accumulate in the pancreas of T1D patients opens the door to exploiting this noninvasive imaging method to follow T1D progression and monitoring the ability of immunomodulatory agents to clear insulitis.     

Reversal of beta-cell suppression in vitro in pancreatic islets isolated from nonobese diabetic mice during the phase preceding insulin-dependent diabetes mellitus.

Insulin-dependent diabetes mellitus (IDDM) is characterized by a progressive autoimmune destruction of the pancreatic beta-cells. One of the best-suited animal models for IDDM is the nonobese diabetic (NOD) mouse. In this investigation pancreatic islets were isolated from female NOD mice aged 5-7, 8-11, and 12-13 wk and examined immediately (day 0) or after 7 d of culture (day 7). The mice showed a progressive disturbance in glucose tolerance with age, and a correspondingly increased frequency of pancreatic insulitis. Islets isolated from the oldest mice often contained inflammatory cells on day 0, which resulted in an elevated islet DNA content. During culture these islets became depleted of infiltrating cells and the DNA content of the islets decreased on day 7. Islets of the eldest mice failed to respond with insulin secretion to high glucose, whereas a response was observed in the other groups. After culture all groups of islets showed a markedly improved insulin secretion. Islets from the 12-13-wk-old mice displayed a lower glucose oxidation rate at 16.7 mM glucose on day 0 compared with day 7. Islet (pro)insulin and total protein biosynthesis was essentially unaffected. In conclusion, islets obtained from 12-13-wk-old NOD mice exhibit an impaired glucose metabolism, which may explain the suppressed insulin secretion observed immediately after isolation. This inhibition of beta-cell function can be reversed in vitro. Thus, there may be a stage during development of IDDM when beta-cell destruction can be counteracted and beta-cell function restored, provided the immune aggression is arrested.     

Hormonal changes in severely uncontrolled type 1 (insulin-dependent) diabetes mellitus

To investigate endocrinological changes associated with severely uncontrolled type 1 (insulin-dependent) diabetes mellitus 27 patients (19 men, eight women) with ketoacidosis or severe ketonuria (= group 1) were examined on admission and after recovery. For comparison 13 non-ketotic patients (seven men, six women), admitted for adjustment of treatment because of poor diabetic control (= group 2), and 20 healthy controls were studied. On admission, the serum testosterone levels in men were lower in group 1 (15.1 +/- 2.0 nmol l-1) (mean +/- SEM) than in group 2 (27.2 +/- 2.8 nmol l-1) (p less than 0.01) and healthy controls (20.6 +/- 2.0 nmol l-1) (p less than 0.05). During treatment the testosterone levels in group 1 rapidly rose to the control level. The serum oestradiol levels in women were low in group 1 both on admission and discharge. The serum prolactin levels were low in female patients in group 1 (119 +/- 17 mIU l-1) compared with the women in group 2 (315 +/- 75 mIU l-1) (p less than 0.05). On admission the serum cortisol levels were higher and their response to 1 mg of dexamethasone was weaker in group 1 than in group 2 and healthy controls. After recovery the serum cortisol levels fell by 15% (p less than 0.01) and the response to 1 mg of dexamethasone returned to normal in group 1. In group 1 during treatment the serum free T4 and reverse T3 levels fell, and the T3 levels rose, whereas the thyroid stimulating hormone (TSH) levels and their responses to TRH remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)