Impact of anti-insulin antibodies on islet transplantation outcome: data from the GRAGIL Network.

BACKGROUND: In patients with type 1 diabetes, insulin antibodies (IA), altering the pharmacokinetics of circulating insulin, might be associated with high glucose concentration, prolonged hypoglycemia, and higher insulin requirement. The impact of IA on islet transplantation has never been explored. Our aim was to evaluate islet transplantation results at 1 year according to the presence of IA. METHODS: Our work is a retrospective, case-control study, comparing IA-negative and IA-positive patients among the cohort of patients with type 1 diabetes transplanted within the Swiss-French GRAGIL network between 2003 and 2010. RESULTS: Data about IA were available for 17 patients. Before islet transplantation, 10 patients (59%) were screened positive for IA. At 12 months after transplantation, IA-positive patients reached insulin independence less frequently than IA-negative patients (cumulative incidence of insulin independence, 22.2% vs. 71.4%; P=0.02); ß score was ≥7 in 43% of IA-negative patients versus 0% in IA-positive patients (P=0.022). When comparing IA-positive patients with IA-negative patients, insulin dose was 0.15 U/kg (0.10-0.18 U/kg) versus 0.01 U/kg (0-0.09 U/kg) (P=0.2); HbA1c was 6.1% (5.8%-6.3%) versus 6.1% (5.9%-6.8%) (P=0.16); basal C-peptide level was 460 ρmol/L (350-510 ρmol/L) versus 265 ρmol/L (177-405 ρmol/L) (P=0.28); occurrence of hypoglycemia was 12.5% versus 16.5% (P=0.9); and homeostatic model assessment insulin resistance was 1.25 (1-2.4) versus 0.7 (0.52-0.92) (P=0.01). CONCLUSION: After islet transplantation, IA-positive patients achieved insulin independence less frequently, exhibiting lower ß score and higher homeostatic model assessment insulin resistance compared with IA-negative patients. However, in both groups, islet transplantation restored good glycemic control and drastically reduced hypoglycemia and insulin requirements.

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.

Functional silencing is initiated and maintained in immature anti-insulin B cells.

Mechanisms of B cell tolerance act during development in the bone marrow and periphery to eliminate or restrict autoreactive clones to prevent autoimmune disease. B cells in the spleens of mice that harbor anti-insulin BCR transgenes (125Tg) are maintained in a functionally silenced or anergic state by endogenous hormone, but it is not clear when and where anergy is induced. An in vitro bone marrow culture system was therefore used to probe whether small protein hormones, a critical class of autoantigens, could interact with the BCR to induce anergy early during B cell development. Upon exposure to insulin, anti-insulin (125Tg) immature B cells show similar hallmarks of anergy as those observed in mature splenic B cells. These include BCR down-regulation, impaired proliferative responses to anti-CD40, and diminished calcium mobilization upon stimulation with BCR-dependent and independent stimuli. Inhibition of calcineurin also results in reduced immature B cell proliferation in a similar manner, suggesting a potential mechanism through which reduced intracellular calcium mobilization may be altering cellular proliferation. Signs of impairment appear after short-term exposure to insulin, which are reversible upon Ag withdrawal. This suggests that a high degree of functional plasticity is maintained at this stage and that constant Ag engagement is required to maintain functional inactivation. These findings indicate that tolerance observed in mature, splenic 125Tg B cells is initiated by insulin in the developing B cell compartment and thus highlight an important therapeutic window for the prevention of insulin autoimmunity.

Impact of insulin antibodies on insulin aspart pharmacokinetics and pharmacodynamics after 12-week treatment with multiple daily injections of biphasic insulin aspart 30 in patients with type 1 diabetes.

OBJECTIVE: This study aimed to evaluate the impact of insulin antibodies on insulin aspart pharmaco-kinetics and pharmacodynamics after 12-week multiple daily injections of biphasic insulin aspart 30 (30% fast-acting and 70% protamine-crystallised insulin aspart, BIAsp30) in patients with type 1 diabetes. METHODS: Twenty-three patients (8 women, 15 men) aged 44.8 (20.6-62.5) years (median and range) with diabetes duration of 19.5 (1.6-44.6) years and haemoglobin (Hb)A(1C) of 9.2% (8.1-12.3%) participated in the study, which consisted of 12-week treatment with multiple injections of BIAsp30. At the end of the treatment period, all patients attended two 24-h profile days 1 week apart for pharmacokinetic and pharmacodynamic assessments. HbA(1C) and insulin antibodies were also determined. RESULTS: Patients were stratified into two groups depending on whether the level of insulin binding to insulin antibodies was below or above 75% (moderate vs high (%, median and range): 62 (15-74) vs 80 (75-89)). High levels of insulin antibodies resulted in about threefold increase in AUC((0 - 24 h)) (the area under the concentration-time curve during 24 h) for total insulin aspart (analysis of variance, P < 0.05). The differences in free insulin aspart pharmacokinetics, insulin pharmacodynamics and HbA(1C) were not statistically significant between patients with different levels of insulin antibodies. Total daily insulin dosage was significantly lower in patients with high than moderate levels of insulin antibodies. CONCLUSIONS: In type 1 diabetic patients, high levels of circulating insulin antibodies result in elevated total, but not free, insulin aspart profiles. Consistent with the finding of similar insulin pharmacodynamics, the long-term glycaemic control is not significantly different between patients with different levels of insulin antibodies.

Anti-insulin antibodies are a cause of hypoglycemia following pancreas transplantation.

OBJECTIVE: Hypoglycemic symptoms have been reported by more than half of pancreas transplantation (PTX) recipients. To better understand the mechanism for the hypoglycemia documented in some of these patients, we studied the glucose and pancreatic hormone response to Sustacal in patients with and without hypoglycemia following PTX. RESEARCH DESIGN AND METHODS: Twelve patients with established, repeated episodes of hypoglycemia following PTX (hypo) were case-matched to PTX recipients without hypoglycemic symptoms (control; n = 7). On the day of the study, fasting glucose, free and total immunoreactive insulin (IRI), C-peptide, proinsulin, and glucagon were drawn (time 0); Sustacal was administered; and glucose, free and total IRI, and C-peptide were assayed at 15, 30, 45, 75, 120, 150, 180, and 240 min. Based on the glucose response to Sustacal, the hypo group was further divided into those whose glucose rose after Sustacal (hypo-high; n = 7) and those with no increase in glucose from baseline concentration (hypo-flat; n = 5). RESULTS: Before the administration of Sustacal, the hypo-high group had a lower fasting free/total IRI (0.26 +/- 0.06, mean +/- SE) than the hypo-flat (0.51 +/- 0.02) or control (0.52 +/- 0.04) groups (both P < 0.05 compared with hypo-high). The glucose response to Sustacal was greatest in the hypo-high group as defined. Area under the curve (AUC) for total IRI following Sustacal was also greatest in the hypo-high group (P < 0.05 compared with both control and hypo-flat groups), but there was no significant difference in free IRI AUC following Sustacal between the three groups. Two individuals developed hypoglycemia during the Sustacal challenge, both in the hypo-high group. CONCLUSIONS: The lower fasting free/total IRI ratio and greater increase in glucose and total IRI in response to Sustacal in the hypo-high group compared with either the hypo-flat or control groups are consistent with the presence of significant quantities of anti-insulin antibodies in the hypo-high group. Because anti-insulin antibodies are, in turn, an established cause of episodic hypoglycemia, this study provides the first data to support the hypothesis that significant quantities of anti-insulin antibodies are a cause of symptomatic hypoglycemia following PTX in some recipients.

First phase insulin release in the non-obese diabetic mouse: correlation with insulitis, beta cell number and autoantibodies.

The ontogenic variation of beta cell function and its relationship with the degree of islet damage and levels of autoantibodies have been studied in the non-obese diabetic (NOD) mouse model. We conducted in vivo first phase insulin release (FPIR) in response to intravenous glucose and studied its correlation with the degree of insulitis, islet cell antibody (ICA) and insulin autoantibody (IAA) levels in female NOD mice cross-sectionally at days 40 (n = 19), 90 (n = 21), 150-160 (n = 21) and day 250 (n = 20). The mean +/- SEM FPIR values showed an age-related decline from day 40 (46.2 +/- 5.3 microU/ml) to day 150-160 (17.8 +/- 2.5 microU/ml) and then doubled at day 250 (34.5 +/- 5 microU/ml), while the mean +/- SEM insulitis scores increased progressively until day 150-160 (61.7 +/- 6.1%) and then declined slightly at day 250 to 50.2 +/- 6.2%. In female NOD mice with spontaneous diabetes (n = 4) and streptozotocin-induced diabetic Swiss mice (n = 5) FPIR was either absent or greatly attenuated. A statistically significant inverse correlation between FPIR and insulitis was found among NOD mice at days 90 (P = 0.02; r = -0.52) and 150-160 (P = 0.03; r = -0.48). However, no statistically significant correlation was observed at days 40 and 250. Morphometric techniques applied to day 150-160 pancreatic sections showed a statistically significant negative correlation between insulitis and beta cell number per unit area of islet tissue (P = 0.0001; r = - 0.75). At this age some islet beta cells showed different intensities of staining by immunofluorescence.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of vagus nerve in increased DNA synthesis after hypothalamic ventromedial lesions in rat liver.

We recently reported that ventromedial hypothalamic (VMH) lesions produced an increase in DNA content in rat liver. In the present study, we examined the mechanism of increased hepatic DNA content produced by VMH lesions. Hepatic DNA content began to increase 3 days after VMH lesioning and continued to increase until 7 days after the lesioning. Hepatic DNA synthesis increased and reached maximum 3 days after the lesioning and then decreased to the initial level 7 days after lesioning. The increased DNA content and synthesis after VMH lesioning were completely inhibited by vagotomy (hepatic vagotomy or bilateral subdiaphragmatic vagotomy) and largely inhibited by the administration of atropine but not by administration of anti-insulin antibody. These results suggest that vagus firing produced by VMH lesions stimulates DNA synthesis in rat liver mainly through cholinergic receptor mechanisms.

Microangiopathy in diabetes mellitus: I. Causes, prevention and treatment.

Microangiopathy is the major cause of death in Insulin Dependent Diabetes Mellitus. However, the pathogenesis of microangiopathy is still far from clear. This paper is a review of the literature on diabetic microangiopathy and discusses the current theories concerning its causes, prevention and treatment. The roles of abnormal glucose metabolism, protein glycosylation, genetic factors and puberty as well as the changes in vascular endothelium, capillary permeability and blood constituents, in the development of microangiopathy are discussed. The benefits of strict control of blood glucose concentrations are discussed along with the action of various pharmaceutical preparations such as aldose reductase inhibitors, hydroxyrutosides, pentoxifylline and free radical scavengers currently assessed in the prevention or treatment of diabetic microangiopathy.

Deleterious effect of anti-insulin antibodies on diabetes control.

We studied the effect of anti-insulin antibodies (AIA) on glycemia control in patients with insulin-dependent diabetes (IDD) by following the AIA titer changes with time. Although expected to remain constant, AIA levels were found to either increase or decrease in most patients. These AIA titer changes correlated significantly with changes in glycohemoglobin but not with changes in insulin dose. The results suggest that AIA may have a deleterious effect on glycemia control in IDD.

Clinical significance of insulin antibodies in insulin-treated diabetic patients.

The prevalence and titers of insulin antibodies in insulin-treated patients have markedly decreased, mainly as a consequence of the improvements in the purity of insulin preparations and to a lesser degree because of the changes of species of insulin (human insulin). However, numerous patients still produce antibody levels that may alter insulin pharmacokinetics, leading to higher postprandial blood glucose levels and to an increased risk for delayed hypoglycemia. Although the effects of antibodies on long-term glycemic control are less clear, the metabolic consequences of altered pharmacokinetics are clinically evident in patients in whom near normoglycemia is the goal and who are treated predominantly with short-acting insulin. Lipoatrophy and immunological insulin resistance, which are also antibody-induced phenomena, have become rare. Whether pregnancies in diabetic mothers with antibodies carry an increased risk for serious or fatal complications is not clear; neonates of these mothers are probably at increased risk for neonatal hypoglycemia.

Effect of isologous and autologous insulin antibodies on in vivo bioavailability and metabolic fate of immune-complexed insulin in Lou/M rats.

The in vivo bioavailability, distribution, and metabolic fate of 125I-labeled insulin complexed to isologous and autologous antibodies were studied in inbred Lou/M rats. There was an impaired bioavailability of the 125I-insulin bound to the isologous and autologous antibodies. Very little of the 125I-insulin in these immune complexes could bind to insulin receptors on hepatocytes or renal tubular cells and be degraded, because the amounts of 125I from degraded 125I-insulin in the blood or secreted into the stomach were markedly attenuated in both cases for at least 30 min after injection. There was a simultaneous accumulation of 125I-insulin immune complexes in the liver and the kidneys of Lou/M rats injected with 125I-insulin complexed with isologous antibodies or when insulin-immunized Lou/M rats were injected with 125I-insulin during the same interval. The impaired bioavailability of immune-complexed insulin and altered distribution of radioactivity due to the accumulation of immune complexes in the liver and kidney were also observed in previous experiments in which Lewis rats were injected with xenogenic guinea pig and homologous insulin antibodies. These observations are therefore submitted as evidence that the Lou/M rat is a valid model in which to study the bioavailability of insulin immune complexed to isologous, homologous, and xenogenic antibodies and the metabolic fate of the respective insulin-antibody immune complexes.

[Effect of insulin-binding antibodies on the kinetics of intra- venous insulin in diabetes mellitus]. / Vliianie insulinsviazyvaiushchikh antitel na kinetiku vnutrovenno vvedennogo insulina pri sakharnom diabete.

The kinetics of 131I-labeled intravenous insulin was examined in 13 patients with diabetes mellitus and in 2 nondiabetics, and the kinetics of unlabeled intravenous insulin ('insulrap') was followed up in 7 patients with insulin-dependent diabetes. Antibodies to exogenous insulin were titered in examinees' blood sera. The kinetic curves of labeled and unlabeled insulin were processed with the use of a two-compartmental model, thus obtaining compatible kinetics parameters. This permits the use of routine insulin dosage forms in pharmacokinetic studies, followed by the blood serum insulin radioimmunoassay. Antibodies to exogenous insulin increase the level of insulin dissemination, slow down its elimination from the blood (mostly in the beta-phase) and the total insulin clearance, with the antibody titer rise being parallelled by an acceleration+ of insulin dissemination and by deceleration of its elimination from the blood; besides, the fraction of antibodies, by fixing which insulin is slowly metabolized, increases.

Insulin antibodies do not influence the absorption rate of subcutaneously injected insulin.

The influence of insulin antibodies on absorption rate and plasma free insulin concentrations after subcutaneous injection of insulin, was studied in two groups of insulin-treated diabetic patients, one without insulin antibodies (n = 9) and a second with high plasma concentrations of antibodies (n = 14). Except for antibody concentration there were no differences in clinical variables. During 8 h after the injection of 12 U of iodinated neutral human insulin, residual radioactivity at the injection site, plasma glucose, and free and total insulin were measured. Significant differences in absorption rate of insulin were not found between the groups. Plasma glucose (basal value 16.8 +/- 4.4 SD vs 16.1 +/- 4.2 mmol l-1) and free insulin (basal value 8.3 +/- 1.4 vs 11.4 +/- 2.3 mU l-1, maximum after 90 min 36.9 +/- 19.5 vs 30.5 +/- 18.7 mU l-1) were never significantly different between the groups, nor were areas under the curve for free insulin (191.4 +/- 69.2 vs 170.8 +/- 98.6 mU l-1 h). In the high antibody group a small increase in bound insulin was found.

Regulation by insulin of liver carbamoyl-phosphate synthase II (glutamine-hydrolysing).

Evidence is provided that insulin controls the amount and synthetic rate of liver carbamoyl-phosphate synthase II (EC 6.3.5.5) (synthase II) in rat. In 3- and 6-day starvation, with low plasma insulin, synthase II specific activity decreased to 47 and 30%, respectively, of normal; on re-feeding and with concurrent insulin injections, liver synthase II activity increased to 2.5 and 3 times that of starved rats respectively. Treatment with anti-insulin serum during re-feeding prevented the rise in synthase II activity. In diabetic rats, synthase II activity decreased to 28% of normal and was increased by insulin treatment for 2 and 7 days to 4.8- and 5.6-fold of the activity in diabetic liver; this rise in activity was blocked by actinomycin. Immunotitration demonstrated that alterations in synthase II activity were due to changes in the enzyme amount. In starvation, the relative synthesis rate of synthase II decreased to 44%, with an increase in catabolic rate to 122%; re-feeding returned these to control values. In diabetes the synthase II synthesis rate decreased to 52% and the degradative rate was accelerated to 180%; insulin treatment induced synthesis and returned degradation to the control range. Thus the integrative action of insulin in liver pyrimidine metabolism entails regulation of the amount and turnover of synthase II.

Prolonged fasting hypoglycemia due to insulin antibodies in patient with non-insulin-dependent diabetes mellitus: effect of insulin withdrawal on insulin-antibody-binding kinetics.

Fasting hypoglycemia, which persisted for 3 days after insulin treatment was stopped, occurred in a patient with non-insulin-dependent diabetes mellitus who had inappropriate plasma free-insulin levels (18-25 microU/ml) and extremely high antibody-bound insulin (greater than 20,000 microU/ml) but normal counter-regulatory hormone secretion and plasma C-peptide levels. The amount of antibody-bound insulin decreased in a biphasic pattern over 13 mo of observation with an initial half-life of 35 days and a more gradual decrease with a half-life of 160 days. The number of high-affinity antibody binding sites was virtually identical to the amount of antibody-bound insulin in the patient's plasma. We conclude that the patient's fasting hyperinsulinemia and hypoglycemia were due to release of antibody-bound insulin.

Effect of insulin antibodies and their kinetic characteristics on plasma free insulin dynamics in patients with diabetes mellitus.

To determine the influence of insulin antibodies (and their equilibrium kinetic properties) on the pharmacokinetics of insulin, we examined the relationship between insulin antibody binding and the initial rate of increase, time to peak, and return to baseline of therapeutic doses of insulin injected subcutaneously (0.15 U/kg) and the half-life, distribution space, and metabolic clearance rate of intravenously infused insulin (2 mU/kg/min) in insulin-treated patients with diabetes mellitus. Compared to age-weight-matched nondiabetic subjects, the diabetic subjects had reduced initial rates of increase (0.33 +/- 0.2 v 0.44 +/- 0.03 microU/mL/min, P less than 0.05), delayed time to peak (130 +/- 12 v 86 +/- 8 min, p less than 0.02), and prolonged return to baseline (485 +/- 37 v 313 +/- 13 min, P less than 0.01) of plasma free insulin levels after subcutaneous injection of insulin, and a prolonged half-life (19.8 +/- 5.8 v 4.3 +/- 0.3 min, P less than 0.02), increased distribution space (904 +/- 284 v 109 +/- 10 mL/kg, P less than 0.001), and augmented metabolic clearance rate (28.5 +/- 1.8 v 17.3 +/- 0.7 mL/kg/min, P less than 0.001) after intravenously infused insulin. All of these abnormal parameters were significantly correlated with binding of insulin to insulin antibodies at tracer insulin concentrations (Bo) and with the high affinity of insulin antibody binding sites as determined by Scatchard analysis. However, patients with 125I insulin antibody binding (Bo) less than 10 percent had normal or near normal plasma free insulin pharmacokinetics.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of insulin antibodies in insulin treatment of type I diabetes.

We investigated equilibrium plasma binding patterns of insulin in 45 juvenile diabetics treated with conventional insulin preparations. Insulin binding parameters were evaluated by Scatchard analysis of the binding data. Stable diabetics had significantly lower equilibrium dissociation constants than labile, thus suggesting an enhanced insulin depot effect due to stronger insulin binding. Correlation of insulin binding data with a glycemic control index yielded a positive relationship between insulin antibody binding and the degree of glycemic control. Insulin neutralization as detected by a relationship between maximum binding capacity of high affinity antibodies and insulin requirement could only be found if patients with poor diabetes control were excluded. Similarly, the well-known promoting influence of residual beta-cell functional capacity (assessed by C-peptide levels) on diabetic stability was observed only after exclusion of patients with higher insulin antibody binding. These data suggest that insulin antibodies are influencing insulin treatment of diabetics in a dual way. They may neutralize therapeutic insulin but at the same time they exert an insulin-sparing action by improvement of diabetes control. Occasionally the latter effect may abolish the correlation between diabetes control and beta-cell functional capacity.