Insulin antibodies and insulin autoantibodies

Bioprinted 3D Bionic Scaffolds with Pancreatic Islets as a New Therapy for Type 1 Diabetes-Analysis of the Results of Preclinical Studies on a Mouse Model

Recently, tissue engineering, including 3D bioprinting of the pancreas, has acquired clinical significance and has become an outstanding potential method of customized treatment for type 1 diabetes mellitus. The study aimed to evaluate the function of 3D-bioprinted pancreatic petals with pancreatic islets in the murine model. A total of 60 NOD-SCID (Nonobese diabetic/severe combined immunodeficiency) mice were used in the study and divided into three groups: control group; IsletTx (porcine islets transplanted under the renal capsule); and 3D bioprint (3D-bioprinted pancreatic petals with islets transplanted under the skin, on dorsal muscles). Glucose, C-peptide concentrations, and histological analyses were performed. In the obtained results, significantly lower mean fasting glucose levels (mg/dL) were observed both in a 3D-bioprint group and in a group with islets transplanted under the renal capsule when compared with untreated animals. Differences were observed in all control points: 7th, 14th, and 28th days post-transplantation (129, 119, 118 vs. 140, 139, 140; p < 0.001). Glucose levels were lower on the 14th and 28th days in a group with bioprinted petals compared to the group with islets transplanted under the renal capsule. Immunohistochemical staining indicated the presence of secreted insulin-living pancreatic islets and neovascularization within 3D-bioprinted pancreatic petals after transplantation. In conclusion, bioprinted bionic petals significantly lowered plasma glucose concentration in studied model species.

Congenital beta cell defects are not associated with markers of islet autoimmunity, even in the context of high genetic risk for type 1 diabetes

AIMS/HYPOTHESIS

A key unanswered question in type 1 diabetes is whether beta cells initiate their own destruction or are victims of an aberrant immune response (beta cell suicide or homicide?). To investigate this, we assessed islet autoantibodies in individuals with congenital beta cell defects causing neonatal diabetes mellitus (NDM).

METHODS

We measured autoantibodies to GAD (GADA), islet antigen-2 (IA-2A) and zinc transporter 8 (ZnT8A) in 242 individuals with NDM (median age diagnosed 1.8 months [IQR 0.39-2.9 months]; median age collected 4.6 months [IQR 1.8-27.6 months]; median diabetes duration 2 months [IQR 0.6-23 months]), including 75 whose NDM resulted from severe beta cell endoplasmic reticulum (ER) stress. As a control cohort we also tested samples from 69 diabetes-free individuals (median age collected 9.9 months [IQR 9.0-48.6 months]) for autoantibodies.

RESULTS

We found low prevalence of islet autoantibodies in individuals with monogenic NDM; 13/242 (5.4% [95% CI 2.9, 9.0%]) had detectable GADA, IA-2A and/or ZnT8A. This was similar to the proportion in the control participants who did not have diabetes (1/69 positive [1.4%, 95% CI 0.03, 7.8%], p=0.3). Importantly, monogenic individuals with beta cell ER stress had a similar rate of GADA/IA-2A/ZnT8A positivity to non-ER stress aetiologies (2.7% [95% CI 0.3, 9.3%] vs 6.6% [95% CI 3.3, 11.5%] p=0.4). We observed no association between islet autoimmunity and genetic risk, age at testing (including 30 individuals >10 years at testing) or diabetes duration (p>0.4 for all).

CONCLUSIONS/INTERPRETATION

Our data support the hypothesis that beta cell stress/dysfunction alone does not lead to the production of islet autoantibodies, even in the context of high-risk HLA types. This suggests that additional factors are required to trigger an autoimmune response towards beta cells.

Exogenous Insulin Injection-Induced Stiff-Person Syndrome in a Patient With Latent Autoimmune Diabetes: A Case Report and Literature Review

Stiff-person syndrome (SPS) is highly associated with anti-glutamic acid decarboxylase (GAD) antibody. However, GAD antibodies alone appear to be insufficient to cause SPS, and they possibly are involved in only part of its pathophysiology. It is suspected that the symptoms of SPS get precipitated by external stimuli. Here, we briefly introduce the case of a patient with latent autoimmune diabetes who developed SPS through the action of subcutaneously injected insulin. A 43-year-old man was diagnosed with diabetes and initially well-controlled with oral hypoglycemic agents but progressed to requiring insulin within 1 year of diagnosis. Two months after the initiation of basal insulin therapy, he presented with abdominal stiffness and painful muscle spasms, involving the lower limbs, which resulted in walking difficulty, and thus, he refused insulin injections thereafter. He had been treated with oral anti-diabetic agents instead of insulin for 10 years until premixed insulin twice daily was started again due to poor diabetes control. Immediately after insulin injection, abdominal muscle rigidity and spasms were noted. When insulin was not administered, frequent episodes of diabetic ketoacidosis occurred. Serum GAD antibody test was positive and there was no positivity for islet antigen-2 antibody. A glucagon stimulation test demonstrated relative insulin deficiency, indicative of latent autoimmune diabetes in adults (LADA). Tolerable muscle rigidity was achieved when the dosage of basal insulin was split into two separate daily injections with lower amounts of units per injection. This case highlights a different form of autoimmune diabetes in SPS. To our knowledge, this is the first report of SPS described shortly after the initiation of insulin therapy that required basal insulin to achieve tolerable muscle symptoms and better glucose control, without the development of diabetic ketoacidosis.

Expansion of CD4+CD25+FOXP3+ regulatory T cells in infants of mothers with type 1 diabetes

BACKGROUND

Reduced risk for type 1 diabetes (T1D) has been reported in the offspring of mothers with T1D when compared with children of affected fathers.

OBJECTIVE

To evaluate the hypothesis that exposure of the offspring to maternal insulin therapy induces regulatory mechanisms in utero, we compared the FOXP3 expressing regulatory T cells in cord blood (CB) of infants born to mothers with or without T1D.

SUBJECTS AND METHODS

Cord blood mononuclear cells (CBMCs) from 20 infants with maternal T1D and from 20 infants with an unaffected mother were analyzed for the numbers of CD4+CD25+FOXP3+ cells ex vivo and after in vitro stimulation with human insulin by flow cytometry. The mRNA expression of FOXP3, NFATc2, STIM1, interleukin (IL)-10, and transforming growth factor (TGF)-β was measured by real-time reverse transcription polymerase chain reaction.

RESULTS

The percentage of FOXP3+ cells in CD4+CD25(high) cells was higher in the CB of the infants with maternal T1D when compared with the infants of unaffected mothers (p = 0.023). After in vitro insulin stimulation an increase in the percentage of FOXP3+ cells in CD4+CD25(high) cells (p = 0.0002) as well as upregulation of FOXP3, NFATc2, STIM1, IL-10, and TGF-β transcripts in CBMCs (p < 0.013 for all; Wilcoxon test) was observed only in the offspring of mothers with T1D, in whom the disease-related PTPN22 allele was associated with reduced STIM1 and NFATc2 response in insulin-stimulated CBMCs (p = 0.007 and p = 0.014).

CONCLUSIONS

We suggest that maternal insulin treatment induces expansion of regulatory T cells in the fetus, which might contribute to the lower risk of diabetes in children with maternal vs. paternal diabetes.

Antibodies against insulin measured by electrochemiluminescence predicts insulitis severity and disease onset in non-obese diabetic mice and can distinguish human type 1 diabetes status

BACKGROUND

The detection of insulin autoantibodies (IAA) aids in the prediction of autoimmune diabetes development. However, the long-standing, gold standard 125I-insulin radiobinding assay (RBA) has low reproducibility between laboratories, long sample processing times and requires the use of newly synthesized radiolabeled insulin for each set of assays. Therefore, a rapid, non-radioactive, and reproducible assay is highly desirable.

METHODS

We have developed electrochemiluminescence (ECL)-based assays that fulfill these criteria in the measurement of IAA and anti-insulin antibodies (IA) in non-obese diabetic (NOD) mice and in type 1 diabetic individuals, respectively. Using the murine IAA ECL assay, we examined the correlation between IAA, histopathological insulitis, and blood glucose in a cohort of female NOD mice from 4 up to 36 weeks of age. We developed a human IA ECL assay that we compared to conventional RBA and validated using samples from 34 diabetic and 59 non-diabetic individuals in three independent laboratories.

RESULTS

Our ECL assays were rapid and sensitive with a broad dynamic range and low background. In the NOD mouse model, IAA levels measured by ECL were positively correlated with insulitis severity, and the values measured at 8-10 weeks of age were predictive of diabetes onset. Using human serum and plasma samples, our IA ECL assay yielded reproducible and accurate results with an average sensitivity of 84% at 95% specificity with no statistically significant difference between laboratories.

CONCLUSIONS

These novel, non-radioactive ECL-based assays should facilitate reliable and fast detection of antibodies to insulin and its precursors sera and plasma in a standardized manner between laboratories in both research and clinical settings. Our next step is to evaluate the human IA assay in the detection of IAA in prediabetic subjects or those at risk of type 1 diabetes and to develop similar assays for other autoantibodies that together are predictive for the diagnosis of this common disorder, in order to improve prediction and facilitate future therapeutic trials.

Pan-insulin allergy and severe lipoatrophy complicating Type 2 diabetes

BACKGROUND

  Insulin allergy is a rare complication of insulin use. Localized lipoatrophy is also known to occur following subcutaneous injections of insulin.

CASE REPORT

  A 53-year-old non-obese female patient with Type 2 diabetes displayed local allergic-type symptoms to all available insulin preparations. This was complicated by the development of severe lipoatrophy on her abdominal and thigh injection sites and subsequently resulted in suboptimal glycaemic control.

CONCLUSIONS

  Whilst uncommon, insulin allergy and lipoatrophy can cause major problems in diabetic management. Potential pathophysiological mechanisms and a stepwise approach to management are discussed.

Circulating insulin antibodies: influence of continuous subcutaneous or intraperitoneal insulin infusion, and impact on glucose control

The purification of animal insulin preparations and the use of human recombinant insulin have markedly reduced the incidence, but not completely suppressed, the development of anti-insulin antibodies (IAs). Advances in technologies concerning the mode of delivery of insulin, i.e. continuous subcutaneous insulin infusion (CSII), continuous peritoneal insulin infusion (CPII) and more recently inhaled insulin administration, appear to significantly increase circulating levels of immunoglobulin G (IgG) anti-IAs in diabetic patients. However, the increase is usually moderate and mostly transient as compared to previous observations with poorly purified animal insulin preparations. The clinical impact of these circulating anti-IAs remains unclear. Nevertheless, several studies have suggested that antibodies could retard insulin action, leading to a worsening of postprandial hyperglycaemia and/or serve as a carrier, thus leading to unexpected hypoglycaemia. CPII may be associated with more marked and sustained increase in IAs levels, possibly related to the use of an unstable insulin and the formation of immunogenic aggregates of insulin. The possible clinical consequences of these high levels of IAs remain to be evaluated because a low-glucose morning syndrome or severe insulin resistance with ketone bodies production have been reported in some cases. In conclusion, even if CSII and CPII may promote the development of circulating IAs, this increase does not lead to immunological insulin resistance, compared to that previously described with animal non-purified insulin preparations, and seems to have only marginal influence on blood glucose control or complications in most diabetic patients.

The relationship between immune-mediated Type 1 diabetes mellitus and ethnicity

OBJECTIVE

To determine the proportion of adults with newly diagnosed Type 1 diabetes that had immune-mediated disease (IMD).

SUBJECTS AND METHODS

Two hundred fifteen patients with hyperglycemia and symptoms of insulin deficiency were screened for antibodies [islet cell antibodies (ICA), insulin autoantibodies (IAA), and glutamatic acid decarboxylase antibodies (GADA(65))] and HLA DR/DQ markers of IMD.

RESULTS

The mean age was 34 years and the mean BMI was 30.0 kg/m(2); 21.8% were non-Hispanic white (NHW), 27% were Latin American (LA), 47.9% were African American (AA), and 3.3% of other (OT) ethnic origins. Sixty individuals (28%) had one or more autoantibodies [Ab(+)]: 62% of NHW, 19% of AA, and 19% of LA. BMI was significantly lower (P<.01) in Ab(+). At least one HLA-DQ allele for susceptibility for IMD was identified in 52% of Ab(+).

CONCLUSIONS

These results suggest that islet cell autoantibodies and HLA markers of susceptibility for IMD are frequent in individuals of varying ethnic backgrounds, older age at onset, and higher body weight. Since early insulin therapy could delay what may otherwise be rapid progression to complete insulinopenia in patients with IMD, screening of adult diabetic patients for IMD at diagnosis may be of benefit to long-term management.

Immune responses to insulin aspart and biphasic insulin aspart in people with type 1 and type 2 diabetes

OBJECTIVE

The antibody responses to a novel rapid-acting insulin analog, insulin aspart (IAsp), and their potential clinical correlates were studied with a specifically developed method in 2,420 people with diabetes treated for up to 1 year with preprandial subcutaneous injections of IAsp.

RESEARCH DESIGN AND METHODS

Circulating insulin antibodies were analyzed by radioimmunoassay with (125)I insulin or IAsp tracers and polyethylene glycol precipitation. Four multinational, open, parallel group studies were conducted in Europe and North America, with a total of 1,534 people with diabetes exposed to IAsp and 886 people exposed to human insulin (HI) as meal-related insulin for 6-12 months.

RESULTS

Insulin antibodies specific to HI or IAsp were absent in a majority of patients throughout the 6- to 12-month study periods. A majority of the patients (64-68%) had antibodies cross-reacting between HI and IAsp when entering the studies, with baseline levels (means +/- SD of percent bound/total) of 16.6 +/- 16.3% in study 1 and 10.3 +/- 14.0% in study 4. In all four studies, cross-reactive antibodies increased in patients exposed to IAsp, with a maximum at 3 months, and thereafter there was a decline toward baseline levels at 9-12 months (levels at 3 and 12 months: 22.3 +/- 19.7 and 16.8 +/- 16.5% in study 1 and 21.5 +/- 21.9 and 16.9 +/- 17.4% in study 4). Antibody levels showed similar changes in people with type 1 and type 2 diabetes, and there was no consistent relationship between antibody formation and glycemic control or between antibody formation and safety in terms of adverse events.

CONCLUSIONS

Treatment with IAsp is associated with an increase in cross-reactive insulin antibodies, with a subsequent fall toward baseline values, without any indication of clinical relevance because no effect on efficacy or safety could be identified.

Pregnancy induces nonimmunoglobulin insulin-binding activity in both maternal and cord blood serum

To evaluate whether pregnancy has any effect on insulin antibody levels and to test the concordance between a conventional radioimmunoassay and a new microassay for the detection of insulin antibodies, insulin antibodies were analysed in 104 mothers in early pregnancy and at delivery and in their newborn infants. Thirty-eight of the mothers had type 1 diabetes. The concordance between the assays was high in the samples taken in early pregnancy (95%), but substantially lower in the samples taken at delivery (40%) and in the cord blood samples (68%). A considerable proportion of the mothers at delivery, especially the unaffected mothers (71%), and the newborn infants of the unaffected mothers (32%) were positive for insulin antibodies in the conventional assay but not in the microassay. Insulin antibody levels increased in the mothers, significantly so in the unaffected mothers (P < 0.001), during pregnancy in the conventional assay, whereas in the microassay they decreased significantly (P < 0.01) in affected mothers and remained negative in the unaffected mothers. Since immune complexes are precipitated with protein A specific for IgG in the microassay and with polyethylene glycol lacking specificity for immunoglobulins in the conventional assay, our data indicate that insulin antibody levels decrease on average during pregnancy and that the increasing non-IgG anti-insulin activity observed in the conventional assay is induced by pregnancy and is present in both the maternal and the foetal circulation.

Islet cell antibodies (ICA), insulin autoantibodies (IAA), islet cell surface antibodies (ICSA) and C-peptide in 1031 school children in a population with a high background incidence of IDDM

Islet cell antibodies (ICA), insulin autoantibodies (IAA) and islet cell surface antibodies (ICSA) together with C-peptide were determined in 1031 healthy schoolchildren to evaluate the frequency of autoimmune reactions towards endocrine pancreas and its relation to insulin secretion in non-diabetic children. The prevalence of ICA (levels > 6 JDF units) was 1.4% (14/1012) while 44 children (4.3%) were ICSA-positive and 40 (4%) had IAA. Girls had higher titres of ICSA than boys. Young children (7-8 years) more often had IAA than 12-13-year-old children who, however, had ICA three times more often than the young children. There were no clear associations between the different antibodies. Of the children, 2.4% had very low post-prandial serum C-peptide values (< or = 0.25 nmol/l). Serum C-peptide was higher in girls than in boys (P < 0.001) and in older children than in younger (P < 0.001). Girls with low levels of ICA had high C-peptide values, while girls with high ICA titers had low C-peptide values, the latter perhaps indicating partial beta cell loss. IAA and ICSA were not related to C-peptide values but both positive ICSA and high C-peptide values were most common in the autumn (P < 0.02 and P < 0.0001, respectively). One of the ICA-positive children developed diabetes in 1991, 4 years after the blood sample was taken. Since after 5 years only one of the children has developed IDDM, it can be concluded autoimmune reactions towards endocrine pancreas and insulin may occur in many children without the development of manifest diabetes. Those with high ICA titers may have lost so many beta cells that their insulin secretion is affected, which in some cases might lead to diabetes many years later.

The toxic effects of serum from patients with type 1 diabetes mellitus on mouse neuroblastoma cells: a new mechanism for development of diabetic autonomic neuropathy

The pathogenesis of diabetic neuropathy is incompletely understood. The possibility that humoral neurotoxic factors contribute as a cause of diabetic neuropathy was tested by application of serum from patients with Type 1 and Type 2 diabetes to mouse neuroblastoma cells, which have the characteristics of adrenergic neurons in culture. Serum from patients with Type 1 diabetes and somatic neuropathy significantly inhibited both proliferation and differentiation of neuroblastoma cells, while serum from patients with Type 1 diabetes but no symptoms of neuropathy and patients with Type 2 diabetes and neuropathy had no effect on proliferation, and serum from Type 2 patients only marginally inhibited differentiation. The effects of Type 1 diabetic serum could be reversed by pre-absorption of the serum to neuroblastoma cells, and were independent of glucose levels. Immunoglobulins precipitated from the sera mimicked the effects of whole sera. These results suggest that Type 1 diabetes mellitus causes a change in serum composition, possibly related to autoimmunity, that is capable of contributing to adrenergic autonomic neuropathy in diabetic patients.

Comparison of anti-human insulin antibodies detection by commercial enzyme-linked immunosorbent assay kit, displacement enzyme-linked immunosorbent assay and radioimmunoassay, in Thai diabetic patients

Antibodies specific to human insulin, in sera of Thai diabetic patients and normal healthy individuals, were detected by a commercial enzyme-linked immunosorbent assay (ELISA) kit, displacement ELISA and radioimmunoassay (RIA). Among 36 insulin-treated patients, the antibodies were detected in 22, 23 and 20 individuals, by RIA, commercial ELISA kit and displacement ELISA, respectively. Among those who had never previously received insulin therapy, RIA showed positive results in 5/11 patients with insulin-dependent diabetes mellitus (IDDM) and 1/2 patients with fibrocalculous pancreatic diabetes (FCPD); but were negative in all 26 patients with non-insulin-dependent diabetes mellitus (NIDDM) and 30 normal healthy individuals. The commercial ELISA kit could detect such insulin autoantibodies (IAA) in 4/11 IDDM, 3/26 NIDDM, 2/2 FCPD patients and 4/30 normal controls; while the displacement ELISA showed positive IAA detection in 5/11 IDDM, 2/26 NIDDM, 2/2 FCPD and 2/30 normal controls. By using RIA as the 'gold standard', the commercial ELISA kit had 92.86% sensitivity, 87.01% specificity, 88.57% accuracy, 72.22% positive predictive value and 97.10% negative predictive value; while these indices for the displacement ELISA were 85.71%, 90.01%, 89.52%, 77.42% and 94.59%, respectively.

Immunological studies on type 1 diabetes in identical twins

Diabetes is a multifactorial disease, the pathogenesis of which involves participation of the host immune system in beta cell destruction. Studies on identical twins offer the opportunity to define genetic and non-genetic factors which may contribute to susceptibility to the disease. Our own work indicates that the number and nature, as well as the intensity and persistence of immune abnormalities of cellular and humoral immune responses can be powerful predictors of the disease and also identify twins who have a degree of protection from the disease.