Insulin-dependent diabetes mellitus and autoimmunity: islet-cell autoantibodies, insulin autoantibodies, and beta-cell failure

A metabolic role for CD47 in pancreatic β cell insulin secretion and islet transplant outcomes

Diabetes is a global public health burden and is characterized clinically by relative or absolute insulin deficiency. Therapeutic agents that stimulate insulin secretion and improve insulin sensitivity are in high demand as treatment options. CD47 is a cell surface glycoprotein implicated in multiple cellular functions including recognition of self, angiogenesis, and nitric oxide signaling; however, its role in the regulation of insulin secretion remains unknown. Here, we demonstrate that CD47 receptor signaling inhibits insulin release from human as well as mouse pancreatic β cells and that it can be pharmacologically exploited to boost insulin secretion in both models. CD47 depletion stimulated insulin granule exocytosis via activation of the Rho GTPase Cdc42 in β cells and improved glucose clearance and insulin sensitivity in vivo. CD47 blockade enhanced syngeneic islet transplantation efficiency and expedited the return to euglycemia in streptozotocin-induced diabetic mice. Further, anti-CD47 antibody treatment delayed the onset of diabetes in nonobese diabetic (NOD) mice and protected them from overt diabetes. Our findings identify CD47 as a regulator of insulin secretion, and its manipulation in β cells offers a therapeutic opportunity for diabetes and islet transplantation by correcting insulin deficiency.

Activation pathways that drive CD4+ T cells to break tolerance in autoimmune diseases. Immunol Rev 2022;307:161-190. [PMID: 35142369 PMCID: PMC9255211 DOI: 10.1111/imr.13071]

Autoimmune diseases are characterized by dysfunctional immune systems that misrecognize self as non-self and cause tissue destruction. Several cell types have been implicated in triggering and sustaining disease. Due to a strong association of major histocompatibility complex II (MHC-II) proteins with various autoimmune diseases, CD4+ T lymphocytes have been thoroughly investigated for their roles in dictating disease course. CD4+ T cell activation is a coordinated process that requires three distinct signals: Signal 1, which is mediated by antigen recognition on MHC-II molecules; Signal 2, which boosts signal 1 in a costimulatory manner; and Signal 3, which helps to differentiate the activated cells into functionally relevant subsets. These signals are disrupted during autoimmunity and prompt CD4+ T cells to break tolerance. Herein, we review our current understanding of how each of the three signals plays a role in three different autoimmune diseases and highlight the genetic polymorphisms that predispose individuals to autoimmunity. We also discuss the drawbacks of existing therapies and how they can be addressed to achieve lasting tolerance in patients.

T Cell-Mediated Beta Cell Destruction: Autoimmunity and Alloimmunity in the Context of Type 1 Diabetes

Type 1 diabetes (T1D) results from destruction of pancreatic beta cells by T cells of the immune system. Despite improvements in insulin analogs and continuous blood glucose level monitoring, there is no cure for T1D, and some individuals develop life-threatening complications. Pancreas and islet transplantation have been attractive therapeutic approaches; however, transplants containing insulin-producing cells are vulnerable to both recurrent autoimmunity and conventional allograft rejection. Current immune suppression treatments subdue the immune system, but not without complications. Ideally a successful approach would target only the destructive immune cells and leave the remaining immune system intact to fight foreign pathogens. This review discusses the autoimmune diabetes disease process, diabetic complications that warrant a transplant, and alloimmunity. First, we describe the current understanding of autoimmune destruction of beta cells including the roles of CD4 and CD8 T cells and several possibilities for antigen-specific tolerance induction. Second, we outline diabetic complications necessitating beta cell replacement. Third, we discuss transplant recognition, potential sources for beta cell replacement, and tolerance-promoting therapies under development. We hypothesize that a better understanding of autoreactive T cell targets during disease pathogenesis and alloimmunity following transplant destruction could enhance attempts to re-establish tolerance to beta cells.

Type 1 diabetes pathogenesis - Prevention???

Pathogenesis of type 1 diabetes is multi-faceted, including, autoimmunity, genetics and environment. Autoimmunity directed against pancreatic islet cells results in slowly progressive selective beta-cell destruction ("Primary autoimmune insulitis"), culminating over years in clinically manifested insulin-dependent diabetes mellitus (IDDM). Circulating serum autoantibodies directed against the endocrine cells of the islets of Langerhans (Islet cell autoantibodies - ICAb) are an important hallmark of this disease. Assays for islet cell autoantibodies have facilitated the investigation and understanding of several facets in the pathogenesis of autoimmune diabetes. Their applications have extended into clinical practice and have opened new avenues for early preclinical prediction and preventive prophylaxis in IDDM/type 1 DM. Recently, surprisingly, differences in insulin content between T1DM islets, as well as, 'patchy' or 'lobular' destruction of islets have been described. These unique pathobiological phenomena, suggest that beta cell destruction may not always be inexorable and inevitably complete/total, and thus raise hopes for possible therapeutic interruption of beta cell autoimmunity - destruction and cure of type 1 diabetes. "Recurrent or secondary autoimmune insulitis" refers to the rapid reappearance of islet cell autoantibodies post pancreas transplant, and selective islet beta cell destruction in the grafted pancreas [never forgetting or "anamnestic" beta cell destructive memory], in the absence of any graft pancreas rejection [monozygotic twin to twin transplantation]. The one definite environmental factor is congenital rubella, because of which a subset of children subsequently develop type 1 diabetes. The putative predisposing factors are viruses, gluten and cow's milk. The putative protective factors include gut flora, helminths, viral infections, and Vitamin D. Prevention of T1DM can include: Primary prevention strategies before the development of autoantibodies and Secondary prevention regimens after autoantibody development. Once islet cell autoantibodies have developed, the goal is to establish a therapeutic regimen to preserve at least 90% of the beta cells, and prevent the development of hyperglycaemia. The targets for T1DM reversal should include autoimmunity, beta cell regeneration and protection of beta cell mass. Anti-CD3 teplizumab and anti-CD3 otelixizumab have been shown to provide C-peptide preservation. The unanswered questions in diabetes research include elimination of autoimmune memory responses, reestablishment of immune self-tolerance, and mechanisms of disease initiation.

Metabolic abnormalities in the pathogenesis of type 1 diabetes

Clinical onset of type 1 diabetes (T1D) is thought to result from a combination of overt beta cell loss and beta cell dysfunction. However, our understanding of how beta cell metabolic abnormalities arise during the pathogenesis of disease remains incomplete. Despite extensive research on the autoimmune nature of T1D, questions remain regarding the time frame and nature of beta cell destruction and dysfunction. This review focuses on the characterizations of beta cell dysfunction in the prediabetic and T1D human and mouse model. Studies have shown evidence supporting progressive loss of beta cell mass and function prior to T1D onset, while other scientists argue beta cell destruction occurs later in the disease process. Determining the time frame of beta cell destruction and identifying metabolic mechanisms that drive beta cell dysfunction has high potential for successful interventions to maintain insulin secretion for individuals with established T1D as well as those with prediabetes.

Delivering on George Eisenbarth's visionary pursuit of understanding pathogenesis and prevention of type 1 diabetes

George Eisenbarth's pioneering and visionary research has provided a critical foundation that will be built on in the years ahead as we progress toward prevention of type 1 diabetes. His almost 30-year old model that type 1 diabetes was a chronic and predictable autoimmune disease with multiple identifiable progressive stages with a potential for interventions to prevent progression to symptomatic diabetes has stood the test of time. To deliver on the Eisenbarth vision and his "unfinished journey," the field needs: (1) to improve detection of risk of type 1 diabetes, (2) to improve staging and prediction of progression, (3) to perform smaller, shorter, practical, and an increased number of prevention clinical trials, and (4) to increase awareness of the potential for risk detection, staging, and prevention of type 1 diabetes and benefit/risk of prevention.

Mechanistic biomarkers for clinical decision making in rheumatic diseases

The use of biomarkers is becoming increasingly intrinsic to the practice of medicine and holds great promise for transforming the practice of rheumatology. Biomarkers have the potential to aid clinical diagnosis when symptoms are present or to provide a means of detecting early signs of disease when they are not. Some biomarkers can serve as early surrogates of eventual clinical outcomes or guide therapeutic decision making by enabling identification of individuals likely to respond to a specific therapy. Using biomarkers might reduce the costs of drug development by enabling individuals most likely to respond to be enrolled in clinical trials, thereby minimizing the number of participants required. In this Review, we discuss the current use and the potential of biomarkers in rheumatology and in select fields at the forefront of biomarker research. We emphasize the value of different types of biomarkers, addressing the concept of 'actionable' biomarkers, which can be used to guide clinical decision making, and 'mechanistic' biomarkers, a subtype of actionable biomarker that is embedded in disease pathogenesis and, therefore, represents a potentially superior biomarker. We provide examples of actionable and mechanistic biomarkers currently available, and discuss how development of such biomarkers could revolutionize clinical practice and drug development.

A radioligand binding assay to measure anti-thyroperoxidase autoantibodies in mice

Autoimmune (Hashimoto's) thyroiditis is a chronic inflammatory disease which affects >3% of the population and shows an increasing prevalence with increasing age. Anti-thyroid autoantibodies, particularly against thyroperoxidase (also known as thyroid peroxidase or TPO), occur commonly in humans with autoimmune thyroid disease, and assays for anti-TPO autoantibodies are used in clinical diagnosis. In contrast anti-TPO autoantibodies have not been observed in classical mouse models of autoimmune thyroiditis, except in cases where mice were deliberately immunized with TPO. In the past, detection of anti-TPO autoantibodies in mice has relied on an indirect immunofluorescence assay (iIFA) which screens for thyroid follicle membrane staining in frozen sections of mouse thyroid glands. Since recent transgenic mouse models of autoimmune thyroiditis spontaneously develop anti-TPO autoantibodies, an assay other than serial dilution and iIFA would be useful to detect and quantify these autoantibodies. In this paper we describe such an assay, based on the capacity of autoimmune mouse sera to bind to the extracellular domain of mouse TPO which was produced in a radioactively labeled form using a coupled in vitro transcription/translation system. The same approach, using human TPO, could provide a highly sensitive method to detect anti-TPO autoantibodies in humans.

The potential for stem cell therapy in diabetes

Both type 1 and type 2 diabetes are characterized by a marked deficit in beta-cell mass causing insufficient insulin secretion. Beta-cell replacement strategies may eventually provide a cure for diabetes. Current therapeutic approaches include pancreas and islet transplantation, but the chronic shortage of donor organs restricts this treatment option to a small proportion of affected patients. Moreover, recent evidence shows a progressive decline in beta-cell function after islet transplantation so that most patients have to revert to insulin treatment within a few years. In this article recent progress in the generation, culture and targeted differentiation of human embryonic stem (ES) cells is reviewed, and some of the issues surrounding their use as a source of beta-cells are discussed.

Insulin autoantibodies are of less value compared with islet antibodies in the clinical diagnosis of autoimmune type 1 diabetes in children older than 3 yr of age

BACKGROUND

Insulin autoantibodies (IAA), antibodies against endogenous insulin, may be detected in type 1 diabetic children before the start of insulin treatment.

OBJECTIVE

To relate IAA to islet antibodies (i.e., islet cell antibodies [ICA], and antibodies against two ICA-related islet antigens, glutamic acid decarboxylase 65 [GADA] and protein tyrosine phosphatase IA-2 [IA-2 A]) at diagnosis, and to endogenous beta-cell function at follow-up after diagnosis in diabetic children.

SUBJECTS

We investigated 74 children, aged 1-15 yr, at the diagnosis of diabetes and 1-10 yr later. Insulin treatment may induce antibody development against exogenous insulin. Patients with insulin treatment > or = 1 wk (n = 5) were therefore excluded from the final analysis.

METHODS

Radioligand-binding assays based on human recombinant antigen were used to measure IAA, GADA, and IA-2 A. ICA were determined with indirect immunofluorescence.

RESULTS

IAA were detected at a significantly lower frequency (43%; p < or = 0.001) than ICA (86%), GADA (72%), and IA-2 A (80%). In agreement, IAA measurements only marginally increased the frequency of positive autoimmune markers at diagnosis of diabetes (from 97 to 99% positive for at least one autoantibody). Preserved beta-cell function (detectable fasting p-C-peptide levels) was found in only nine patients, who were older (13 +/- 3 vs. 7 +/- 6 yr, p = 0.002) and had fewer of the antibodies (IAA, GADA, IA-2 A, ICA) in high titer (> median) compared with 60 patients with undetectable p-C-peptide levels.

CONCLUSIONS

Insulin autoantibodies are of less clinical value compared with islet antibodies in the diagnosis of autoimmune type 1 diabetes in children.

Islet immunoisolation: experience with biopolymers

Incidence of Type I diabetes is increasing globally and has become a major health concern. There is enough evidence suggesting involvement of autoimmunity in destruction of insulin-producing islets of langerhans which leads to impaired glucose homeostasis. Islet transplantation is one of the approaches that received wide attention. Due to the autoimmune nature of the disease. strategies to protect transplanted islet graft from rejection are sought. Immunoisolation of islets inside semipermeable biocompatible materials is amongst them. Natural biopolymers have been used extensively as immunoisolation materials due to their satisfactory biocompatiblity and tissue tolerance. Here we attempt to address the need for islet immunoisolation and our experience in using natural biopolymers such as chitosan, cellulose and alginate for this application.

Insulin intervention to preserve beta cells in slowly progressive insulin-dependent (type 1) diabetes mellitus

Slowly progressive insulin-dependent (type 1) diabetes mellitus (SPIDDM) is characterized by (1) late age of onset, with initial features of NIDDM and subsequent progression to insulin-dependent stage; (2) high predictive value of autoantibodies against glutamic acid decarboxylase (GADAb) and islet cell antibodies (ICA) for progression of beta cell failure; (3) less predominant T cell response, which may attack and eventually destroy beta-cells in affected pancreas. These findings may suggest a rationale for intervention to prevent slowly progressive beta cell dysfunction in this type of diabetes. We identified three independent risk factors for progression of beta cell failure in SPIDDM: (1) sulfonylurea treatment; (2) ICA-positive periods; and (3) initial body weight. We hypothesized that removal of the risk factors for further progression of beta cell dysfunction will have beneficial effects on intervention strategy in treating SPIDDM. In our pilot study, we used a small dose of insulin instead of sulfonylurea in the early stage of treatment of patients with SPIDDM. Insulin-treated SPIDDM patients had a sustained C peptide response (CPR), while most of sulfonylurea-treated patients progressed to an insulin-dependent state. We organized a randomized multicenter clinical trial to study early treatment to prevent the progression of beta cell dysfunction in SPIDDM (the Tokyo Study). It was demonstrated that early intervention with insulin therapy is an effective treatment modality in the early stage of SPIDDM patients who had preserved beta cell function at entry (integrated value of serum C peptide values at 0, 30, 60, 90, and 120 minutes; Sigma CPR >or= 10 ng/mL) and high GADAb (>10 U/mL). Preventive insulin treatment was ineffective in the patients who had diminished insulin reserve at entry (Sigma CPR < 10 ng/mL). Insulin intervention to preserve beta cell dysfunction in SPIDDM is effective and safe in patients with preserved beta cell function and high GADAb titers at the initiation of insulin.

A novel micro-assay for insulin autoantibodies

Insulin autoantibodies (IAA) are established markers of Type 1 diabetes and are widely used for the prediction of this disease. Standard assays require relatively large serum volumes for reliable measurement of IAA, limiting their use in young children. We have developed a novel small volume assay which is suitable for screening large numbers of samples. For reasons of economy we have adopted a two-stage strategy in which all samples are screened for insulin binding and those with raised levels are quantified in an assay using competitive displacement. Using this assay 126 out of 241 (52%) newly diagnosed IDDM patients (median age 10.2, range 1.3-20.7 years) had IAA levels above the 99th centile of 2860 schoolchildren (median age 11.3, range 9.0-13.8 years), including 81 out of 117 (69%) patients below the age of 10 years. The assay compared well overall when measuring IAA in direct comparison with a conventional assay. We conclude that reliable measurement of IAA is possible on less than 50 microl of serum using this novel assay and that this should facilitate large scale screening, particularly in young children.

Naturally occurring insulin autoantibodies in neonates of normal pregnancies and their relationship to insulinemia and birth weight

OBJECTIVE

The objectives of this study were to determine whether insulin autoantibodies are present in umbilical cord blood from normal pregnancies, determine whether cord blood insulin autoantibody levels correlate with respective maternal levels at delivery, determine whether cord blood insulin autoantibody levels are related to cord blood or maternal insulin levels, and to determine what relationship neonatal birth weight has with either cord blood insulin autoantibody and insulin levels or maternal insulin autoantibody and insulin levels.

STUDY DESIGN

Paired umbilical cord and maternal serum samples were taken from 70 normal subjects at delivery. Measurements of serum insulin autoantibody (competitive charcoal radiobinding assay) and insulin (radioimmune inhibition assay) levels were performed. Multiple linear regression analysis and paired t tests were used for data analyses.

RESULTS

Neonatal insulin autoantibody levels (120 nU/ml) were more than two times higher than maternal levels (49 nU/ml) (p < 0.001). No correlation was observed between neonatal and maternal insulin autoantibody levels (r = 0.14, p = 0.25). A positive correlation of both neonatal and maternal insulin with birth weight was observed (r = 0.28, p < 0.02; and r = 0.36, p < 0.01, respectively).

CONCLUSIONS

These results suggest that the insulin autoantibody levels in fetal cord blood are not related to maternal levels in normal uncomplicated pregnancies. In addition, insulin levels in both maternal and neonatal circulations were positively correlated with increased birth weight in the normal pregnancies studied.

Insulin as a target antigen in autoimmune diabetes: a natural repertoire as the source of antibody response

A solid-phase immunoenzymatic technique with B1- or B29-biotinylated insulin coupled to avidin-coated wells was used to characterize serum anti-insulin antibodies and to locate insulin antibody-producing B lymphocytes in different organs of mice. Low natural serum anti-insulin IgM and IgG antibodies were found in ten different healthy inbred strains of mice. Prediabetic non-obese diabetic (NOD) mice had significantly higher measurements than BALB/c mice (P < 0.05). Anti-insulin IgM antibody-producing B lymphocytes were found in bone marrow and spleen of NOD mice and healthy strains of mice, but not in peripheral lymph nodes, thymus, blood or pancreas. B29-fixed insulin was more frequently recognized than B1-fixed insulin. There was no relationship to the MHC or to other immune markers. IgG insulin antibody-producing cells were not detected. IgG insulin antibody-producing cells appeared in the draining lymph node and in the blood 10 days after immunization with insulin. IgM insulin-recognizing cells in the spleen were reduced in number during the same period (P < 0.05-0.01 for BALB/c, DBA2, B10.D2 and NOD), suggesting migration of these cells. This was tested by in vivo staining of spleens with the red-fluorescent membrane linker PKH-26 on day 7 after immunization. Cells from immunized lymph nodes were FACS-sorted on day 10. Insulin antibody-producing B lymphocytes with red-fluorescence were found, indicating a splenic origin. Examination of IgG subclasses showed preferential production of complement-fixing IgG2b in sera and lymph node cells of immunized NOD mice (P < 0.05 vs BALB/c).(ABSTRACT TRUNCATED AT 250 WORDS)

Islet cell antibodies predict insulin-dependent diabetes in United States school age children as powerfully as in unaffected relatives

Islet cell antibodies (ICA) in the sera of nondiabetic relatives of patients with insulin-dependent diabetes (IDD) are predictive of the disease, a finding that permits the design of intervention strategies to prevent it. However, 85% or more of patients with new onset IDD have no affected relative. We therefore screened 9,696 schoolchildren between the ages of 5 and 18 yr (mean age 10.7 yr) in Pasco County, Florida for ICA in three surveys during 1984/5, 1987/8, and 1990/1 and have followed them prospectively. Approximately 4,000 of these children have been followed for nearly 8 yr. ICA titers > or = 10 Juvenile Diabetes Foundation units on replicate tests were detected in 57 of the children (0.59%). 10 children have developed diabetes so far, and all had ICA detected beforehand. The likelihood of developing IDD among the ICA-positive children was compared with 2,959 age-matched nondiabetic first degree relatives of IDD probands who were screened for ICA by our laboratory during the same time period and also followed prospectively. Of 103 (3.5%) ICA-positive relatives, 31 have developed IDD. Life table analysis reveals no statistically significant differences in the probability of developing IDD between the ICA-positive schoolchildren and ICA-positive first degree relatives (P = 0.3). The estimated risk of developing IDD by 7 yr in the ICA-positive schoolchildren was 45% (95% confidence interval 15-74%) compared with 43% (confidence interval 22-63%) in the relatives. We conclude that ICA appear to be as predictive of IDD in low-risk schoolchildren as they are in high-risk relatives. These data suggest that it is feasible to predict IDD by screening a general population of schoolchildren for ICA and that those found to be positive could be considered, in addition to relatives, for intervention protocols to prevent the disease.

Studies of autoantibodies reactive with thyroid membrane antigens and insulin in non obese diabetic mice

Enzyme-linked immunosorbent assay (ELISA) was used to study the temporal relationship between the appearance of murine autoantibodies reactive to insulin and thyroid membrane antigens (TMA) and the development of diabetes and thyroiditis in the non obese diabetic (NOD) mouse. Overall, 28% of NOD mice had antibodies specific for mouse thyroid membrane antigens (MTMA), 30% had antibodies to human thyroid membrane antigens (HTMA) and 23% of NOD mice had insulin autoantibodies (IAA), in at least one of their serial monthly blood samples. Non autoimmune BALB/c mice did not develop antibodies to these antigens. Presence of IAA was associated with the development of diabetes and in 87% of cases such antibodies were detected before the diabetes was diagnosed. IAA were usually demonstrated before insulitis. No association between thyroiditis and IAA was noted. Anti-MTMA and anti-HTMA antibodies were detected more frequently in NOD mice with thyroiditis than in those without thyroid inflammation. No significant association was noted between detection of serum anti-TMA antibodies and the development of diabetes. In young mice, anti-TMA antibodies were not detected in the absence of thyroiditis. Western blot analysis of NOD sera positive for MTMA by ELISA revealed a heterogeneous pattern of reactivity. The significance of these findings with respect to the pathogenesis of diabetes and thyroiditis and their association, is discussed.

Factors affecting the insulin autoantibody ELISA

IgG antibodies to insulin are present in insulin-treated patients and are detected in the prodrome of untreated type I diabetes. Sporadic reports of autoantibodies to insulin suggest that they are also present in other disorders. To establish the incidence of insulin autoantibodies in other endocrine and autoimmune diseases an ELISA was used to examine sera from 529 subjects with no prior insulin therapy. These untreated patients included: normal controls (adults and children), newly-diagnosed type I diabetes, first-degree relatives of diabetics, type II diabetes, Graves' hyperthyroidism, and systemic lupus erythematosus. As a positive control group, 280 insulin-treated patients were studied. Measurement of IgG antibodies by direct binding to insulin coated plates was complicated by differences between adult and pediatric populations and by overlap of binding between treated and untreated subjects. Competitive inhibition with excess soluble human insulin overcame these problems and permitted identification of insulin specific binding. Using this approach insulin antibodies were most frequent in insulin-treated diabetics (98%) and in type I diabetics (37%) prior to treatment. The absolute numbers of subjects with insulin autoantibody in the other groups differed depending upon whether a cut-off for binding (mean + 2SD of controls) or for insulin inhibition of binding (45%) was used. Regardless of the criteria used there were subjects (2-24%) in all groups tested with circulating insulin-specific IgG autoantibody detected by ELISA. These low level antibodies detected in solid phase assays may be part of the normal immune repertoire.

Immunological aspects of diabetes mellitus: prospects for pharmacological modification

It is now well known that insulin-dependent diabetes is a chronic progressive autoimmune disease. The prolonged prediabetic phase of progressive beta-cell dysfunction is associated with immunological abnormalities. A prediabetic period is suggested by the appearance of islet cell antibodies, anti-insulin antibodies, and anti-insulin receptor antibodies. The existence of activated T lymphocytes and abnormal T cell subsets are also other markers. There is still no concensus about the use of the immunosuppression superimposed upon conventional insulin therapy in early diagnosed IDDM and the follow-up of the relatives of IDDM patients who share the genetic predisposition and serological markers for the risk of future onset of IDDM. Treatment in the prodromal period cannot be justified because a link between the disease and early markers such as ICA has not been established with certainty (Diabetes Research Program NIH, 1983). Many immunopharmacological manipulations were reported to be effective in animal models. However, most of them are not readily applied to human subjects. Moreover, IDDM patients are now believed to be heterogeneous, with a complex genetic background. HLA-DR, and more recently DQ, are closely related to the genetic predisposition to IDDM but those genes are not themselves diabetogenic. The contribution of autoimmunity does not appear to be uniform, and in some cases, the contribution of virus is considered more important. There is a lack of a marker for the future onset of IDDM. ICA and ICSA were found after mumps infection, but the existence of those autoantibodies and even the co-existence of HLA-DR3 do not always indicate the future trend to insulin dependency. More precise markers will be disclosed through the biochemical analysis of the target antigens on pancreatic beta-cell for islet antibodies and effector T cells. Much safer and more effective immunopharmacological treatment will be developed through animal experimentation using rat and mouse models. The recent development and interest in this field will further facilitate the attainment of the goal for the complete prevention of IDDM.

Presence of insulin autoantibodies at clinical diagnosis of diabetes mellitus type I predicts loss of beta cell function

Recently the spontaneous development of insulin autoantibodies (IAA) has been detected in patients at diagnosis of Type I diabetes mellitus before the beginning of insulin treatment. The present study was undertaken to investigate if the presence of IAA at clinical onset of IDDM may act as a new marker of the beta cell function. The results obtained showed that IAA were present in 44% of newly diagnosed diabetic patients before therapy. Patients without IAA displayed a higher C-peptide secretion than those with IAA, at six months (12.11 +/- 5.08 versus 5.88 +/- 3.25 ng/ml/10 min.)(X +/- SD) and at twelve months (10.45 +/- 3.05 versus 4.90 +/- 5.25 ng/ml/10 min)(X +/- SD) of the follow up period. HbA1 levels, and insulin requirements were similar in both groups (IAA+ and IAA-). We conclude that the presence of insulin autoantibodies at clinical diagnosis, before initiating insulin treatment, may well predict the loss of the beta cell function.

Insulin autoantibodies in the pre-diabetic period: correlation with islet cell antibodies and development of diabetes

IgG and IgM class insulin autoantibodies were measured by an enzyme-linked immunosorbent assay in sera from members of the Barts-Windsor-Middlesex prospective family study for Type 1 (insulin-dependent) diabetes. One hundred and twelve individuals from 28 families were selected for study on the basis of a clearly defined islet cell antibody status. IgG insulin autoantibodies were found to be significantly associated with islet cell antibody positive (n = 30) versus islet cell antibody negative (n = 57) first degree family relatives (p = 0.002), with increased significance (p = 0.0003) if complement-fixing (CF)-islet cell antibody individuals (n = 20) only were considered. In addition, a significant association of IgG insulin autoantibodies with subsequent development of diabetes was observed within the CF-islet cell antibody positive group (p less than 0.0003). No such associations were found for IgM insulin autoantibodies, but a higher prevalence of these autoantibodies was observed in islet cell antibody negative first degree relatives (n = 57) compared with a control group of 73 Blood Bank donors (p = 0.00007), and they were significantly associated with siblings (n = 48) rather than parents (n = 39), (p = 0.001). We conclude that the presence of IgG insulin autoantibodies and CF-islet cell antibodies confer more risk for future development of diabetes than the presence of either marker alone.