Autoimmune forms of hypoglycemia

Recurrent hypoglycemia from insulin autoimmune syndrome

Insulin autoimmune syndrome (IAS) is an uncommon cause of hyperinsulinemic hypoglycemia characterized by autoantibodies to endogenous insulin in individuals without previous exposure to exogenous insulin. IAS is the third leading cause of spontaneous hypoglycemia in Japan, and is increasingly being recognized worldwide in non-Asian populations. We report a case of IAS in a Caucasian woman with recurrent complaints of hypoglycemia, with laboratory findings of serum glucose 2.5 mmol/L (45 mg/dL), insulin 54,930 pmol/L (7,909 μIU/mL), connecting peptide (C-peptide) 4,104 pmol/L (12.4 ng/mL), and a corresponding insulin to C-peptide molar ratio of 13.4 during a spontaneous hypoglycemic event. Autoantibodies to insulin were markedly elevated at > 50 kU/L (> 50 U/mL). IAS should be considered in the differential diagnosis of hypoglycemia in non-diabetic individuals. Distinction from insulinoma is especially crucial to prevent unwarranted invasive procedures and surgical interventions in hypoglycemic patients.

Conformational inactivation induces immunogenicity of the receptor-binding pocket of a bacterial adhesin

Inhibiting antibodies targeting receptor-binding pockets in proteins is a major focus in the development of vaccines and in antibody-based therapeutic strategies. Here, by using a common mannose-specific fimbrial adhesin of Escherichia coli, FimH, we demonstrate that locking the adhesin in a low-binding conformation induces the production of binding pocket-specific, adhesion-inhibiting antibodies. A di-sulfide bridge was introduced into the conformationally dynamic FimH lectin domain, away from the mannose-binding pocket but rendering it defective with regard to mannose binding. Unlike the native, functionally active lectin domain, the functionally defective domain was potent in inducing inhibitory monoclonal antibodies that blocked FimH-mediated bacterial adhesion to epithelial cells and urinary bladder infection in mice. Inhibition of adhesion involved direct competition between the antibodies and mannose for the binding pocket. Binding pocket-specific inhibitory antibodies also were abundant in polyclonal immune serum raised against the functionally defective lectin domain. The monoclonal antibodies elicited against the binding-defective protein bound to the high-affinity conformation of the adhesin more avidly than to the low-affinity form. However, both soluble mannose and blood plasma more strongly inhibited antibody recognition of the high-affinity FimH conformation than the low-affinity form. We propose that in the functionally active conformation the binding-pocket epitopes are shielded from targeted antibody development by ligand masking and that strong immunogenicity of the binding pocket is unblocked when the adhesive domain is in the nonbinding conformation.

Insulin autoimmune syndrome induced by methimazole in a Korean girl with Graves' disease

Hypoglycemia was detected in a 15-year-old girl due to loss of consciousness. She was diagnosed with Graves' disease and was being treated with methimazole for the past 4 months. A paradoxically increased insulin levels was found when she suffered from the hypoglycemic episode. An imaging study showed no mass lesion in the pancreas, and insulin antibodies were found in the serum. She was diagnosed with insulin autoimmune syndrome. Her HLA typing was performed, and it revealed HLA-DRB1 (*)04:06. The patient was treated with a corticosteroid for 2 months. After discontinuing the steroid, the insulin antibody titer decreased dramatically, and she did not have any episode of hypoglycemia since. This is the first report of insulin autoimmune syndrome in a Korean girl, and we have revealed the connection between HLA type and insulin autoimmune syndrome in Korea.

Type B insulin-resistance syndrome presenting as autoimmune hypoglycemia, associated with systemic lupus erythematosus and interstitial lung disease

We describe an unusual case of systemic lupus erythematosus with pulmonary manifestations presenting as hypoglycemia due to anti-insulin receptor antibodies. A 38-year-old female suffered an episode of unconsciousness and was admitted to hospital where her blood glucose was found to be 18 mg/dL. During the hypoglycemic episode, her serum insulin level was inappropriately high (2,207.1 pmol/L; normal range, 18 to 173) and C-peptide level was elevated (1.7 nmol/L; normal range, 0.37 to 1.47). Further blood tests revealed the presence of antinuclear antibodies, anti-double-stranded DNA antibodies, and anti-Ro/SSA, anti-La/SSB, anti-ribonucleoprotein, and anti-insulin receptor antibodies. A computed tomography scan of the abdomen, aimed at tumor localization, such as an insulinoma, instead revealed ground-glass opacities in both lower lungs, and no abnormal finding in the abdomen. For a definitive diagnosis of the lung lesion, video-associated thoracoscopic surgery was performed and histopathological findings showed a pattern of fibrotic non-specific interstitial pneumonia.

Severe hypoglycemia secondary to methimazole-induced insulin autoimmune syndrome in a 16 year old African-American male

Insulin autoimmune syndrome (IAS) or Hirata's disease is a rare disorder characterized by hypoglycemia secondary to insulin autoantibodies (IAb). Over 200 patients have been described from Japan with significantly less numbers being reported from outside the Orient. IAS is more common in patients older than 40 yr of age with reports in the pediatric age group being notably rarer. Exposure to sulfhydryl group containing medications is implicated in the pathogenesis of this syndrome. In this report, we describe a case of IAS in an African-American adolescent. A 16-yr-old healthy African-American male was diagnosed with Graves' disease and started on Methimazole. Four weeks later, he was found unconscious and hypoglycemic (blood sugar 1.5 mmol/L). Evaluation was negative for insulinoma. Insulin antibodies were positive. Oral glucose tolerance test revealed elevated free insulin concentrations with disproportionately elevated total insulin levels. The patient was started on prednisone, diazoxide, and propranolol for management of IAS and hyperthyroidism. Thyroid radio-ablation was subsequently undertaken. The doses of prednisone and diazoxide were tapered and these medications discontinued after 9 months. The insulin antibody levels decreased gradually and became undetectable in 6 months with resolution of the hypoglycemia.

High prevalence of both anti-insulin and anti-insulin receptor antibodies in Korean patients with insulin autoimmune syndrome

We performed a retrospective pooled analysis of 28 patients who had been diagnosed with insulin autoimmune syndrome and evaluated the prevalence of anti-insulin receptor antibodies. Dual positivity for anti-insulin and anti-insulin receptor antibodies was common (53.8%). However, these patients had a similar phenotype compared with insulin receptor antibody-negative patients.

Syndromic insulin resistance: models for the therapeutic basis of the metabolic syndrome and other targets of insulin resistance

OBJECTIVE

To investigate the link between insulin resistance and the metabolic syndrome how to develop treatment approaches.

METHODS

We present 3 cases of extreme syndromic insulin resistance: lipodystrophy, autoantibodies to the insulin receptor, and mutations in the insulin receptor gene, with accompanying discussion of pathophysiology and treatment.

RESULTS

In lipodystrophy, insulin resistance is a direct consequence of leptin deficiency, and thus leptin replacement reverses metabolic syndrome abnormalities, including diabetes and hypertriglyceridemia. The insulin "receptoropathies," including autoantibodies to the insulin receptor and insulin receptor gene mutations, are characterized by extreme insulin resistance and ovarian hyperandrogenism, without dyslipidemia or fatty liver disease. Autoantibodies to the insulin receptor can be treated using an immunosuppressive paradigm adapted from treatment of other autoimmune and neoplastic conditions. Leptin treatment has shown some success in treating hyperglycemia in patients with insulin receptor gene mutations. Treatment for this condition remains inadequate, and novel therapies that bypass insulin receptor signaling, such as enhancers of brown adipose tissue, are needed.

CONCLUSIONS

We present a clinical approach to the treatment of syndromic insulin resistance. The study of rare diseases that replicate the metabolic syndrome, with clear-cut pathophysiology, promotes understanding of novel physiology and development of targeted therapies that may be applicable to the broader population with obesity, insulin resistance, and diabetes.

Type B insulin resistance syndrome induced by systemic lupus erythematosus and successfully treated with intravenous immunoglobulin: case report and systematic review

Type B insulin resistance syndrome is characterized by the formation of autoantibodies against insulin receptors, which can cause severe hyperglycemia and insulin resistance. Systemic lupus erythematosus is the most common underlying diseases of the syndrome. This report details our study of a case involving a Chinese female with type B insulin resistance syndrome as well as systemic lupus erythematosus who completely recovered after undergoing immunosuppressive therapy, specifically pulse therapy utilizing intravenous immunoglobulin. We also conducted search in MEDLINE and Chinese BioMedicine database to identify relevant literatures published in the past 46 years. From our searches, six case reports in Chinese, 15 case reports, and a 28-year perspective article in English met our criteria; a total of 67 cases were included in our report. The mean age of subjects at presentation for groups A, B, and C were 42.95, 44.10, and 41.68 years, respectively, yielding no significant difference between these groups. African Americans were the most susceptible group to type B insulin resistance syndrome, followed by Asians representing 20.90 % of all cases. Comparisons between the three main racial groups surveyed indicated that the mean age of subjects at presentation were very contiguous for African Americans and Asians, and mean age of white people was remarkably higher than either of the first two groups. The syndrome appeared most common among Asian males, and white males were relatively less likely to suffer from type B insulin resistance syndrome. Hypoglycemia was most commonly observed in white people than in other racial groups. Hypoalbuminemia, elevated serum immunoglobulin G, and elevated sedimentation rates were more common in African Americans; Asian cases were more likely to show low serum C3 or C4 and nephritis. Two cases received intravenous immunoglobulin therapy, which has a remarkably rapid effect on insulin resistance.

Hypoglycemia in non-diabetic in-patients: clinical or criminal?

BACKGROUND AND AIM

We wished to establish the frequency of unexpected hypoglycemia observed in non diabetic patients outside the intensive care unit and to determine if they have a plausible clinical explanation.

METHODS

We analysed data for 2010 from three distinct sources to identify non diabetic hypoglycaemic patients: bedside and laboratory blood glucose measurements; medication records for those treatments (high-strength glucose solution and glucagon) commonly given to reverse hypoglycemia; and diagnostic codes for hypoglycemia. We excluded from the denominator admissions of patients with a diagnosis of diabetes or prescribed diabetic medication. Case notes of patients identified were reviewed. We used capture-recapture methods to establish the likely frequency of hypoglycemia in non-diabetic in-patients outside intensive care unit at different cut-off points for hypoglycemia. We also recorded co-morbidities that might have given rise to hypoglycemia.

RESULTS

Among the 37,898 admissions, the triggers identified 71 hypoglycaemic episodes at a cut-off of 3.3 mmol/l. Estimated frequency at 3.3 mmol/l was 50(CI 33-93), at 3.0 mmol/l, 36(CI 24-64), at 2.7 mmol/l, 13(CI 11-19), at 2.5 mmol/l, 11(CI 9-15) and at 2.2 mmol/l, 8(CI 7-11) per 10,000 admissions. Admissions of patients aged above 65 years were approximately 50% more likely to have an episode of hypoglycemia. Most were associated with important co-morbidities.

CONCLUSION

Significant non-diabetic hypoglycemia in hospital in-patients (at or below 2.7 mmol/l) outside critical care is rare. It is sufficiently rare for occurrences to merit case-note review and diagnostic blood tests, unless an obvious explanation is found.

A fully human, allosteric monoclonal antibody that activates the insulin receptor and improves glycemic control

Many patients with diabetes mellitus (both type 1 and type 2) require therapy to maintain normal fasting glucose levels. To develop a novel treatment for these individuals, we used phage display technology to target the insulin receptor (INSR) complexed with insulin and identified a high affinity, allosteric, human monoclonal antibody, XMetA, which mimicked the glucoregulatory, but not the mitogenic, actions of insulin. Biophysical studies with cultured cells expressing human INSR demonstrated that XMetA acted allosterically and did not compete with insulin for binding to its receptor. XMetA was found to function as a specific partial agonist of INSR, eliciting tyrosine phosphorylation of INSR but not the IGF-IR. Although this antibody activated metabolic signaling, leading to enhanced glucose uptake, it neither activated Erk nor induced proliferation of cancer cells. In an insulin resistant, insulinopenic model of diabetes, XMetA markedly reduced elevated fasting blood glucose and normalized glucose tolerance. After 6 weeks, significant improvements in HbA(1c), dyslipidemia, and other manifestations of diabetes were observed. It is noteworthy that hypoglycemia and weight gain were not observed during these studies. These studies indicate, therefore, that allosteric monoclonal antibodies have the potential to be novel, ultra-long acting, agents for the regulation of hyperglycemia in diabetes.

Type B insulin resistance syndrome with diabetic ketoacidosis

Autoimmune syndromes characterized by either insulin receptor antibodies as a type B insulin resistance syndrome or insulin antibodies as an insulin autoimmune syndrome. We report here on a patient who had type B insulin resistance syndrome with insulin and insulin receptor antibodies and this all manifested as diabetic ketoacidosis.

B Cell in Autoimmune Diseases

The role of B cells in autoimmune diseases involves different cellular functions, including the well-established secretion of autoantibodies, autoantigen presentation and ensuing reciprocal interactions with T cells, secretion of inflammatory cytokines, and the generation of ectopic germinal centers. Through these mechanisms B cells are involved both in autoimmune diseases that are traditionally viewed as antibody mediated and also in autoimmune diseases that are commonly classified as T cell mediated. This new understanding of the role of B cells opened up novel therapeutic options for the treatment of autoimmune diseases. This paper includes an overview of the different functions of B cells in autoimmunity; the involvement of B cells in systemic lupus erythematosus, rheumatoid arthritis, and type 1 diabetes; and current B-cell-based therapeutic treatments. We conclude with a discussion of novel therapies aimed at the selective targeting of pathogenic B cells.

Recurrent Drug-Induced Insulin Autoimmune Syndrome in a Patient with Premature Ovarian Failure

Insulin autoimmune syndrome (IAS) is characterized by hypoglycemic attacks, very high insulin levels and the presence of circulating autoantibodies to insulin in patients who have not been treated with exogenous insulin. Approximately half of patients with insulin autoimmune syndrome have a medication history preceding hypoglycemic events. We present the case of a young woman with premature ovarian failure who developed IAS initially after treatment with methimazole and several years later after captopril, and because of coexistent premature ovarian failure was classified as having autoimmune polyglandular syndrome (APS) type 3. Termination of methimazole and Captopril treatment resulted in the disappearance of hypoglycemic episodes. We discuss diagnostic and treatment dilemmas associated with discovering and management of IAS and APS in this patient.

Recurrent hypoglycemia during pregnancies in a woman with multiple autoantibodies including anti-insulin receptor antibody and anti-platelet antibody, whose serum lowered murine blood glucose levels and phosphorylated insulin receptor of CHO-IR cells

We report a rare case of recurrent hypoglycemia in a pregnant woman during the period of pregnancies. She suffered from severe hypoglycemia and intrauterine fetal death during the first pregnancy. Thereafter, there was no hypoglycemia, and no obvious cause of hypoglycemia was found by close examinations. Two years later, at eight weeks into the second pregnancy, hypoglycemia recurred. The patient had multiple auto-antibodies including anti-insulin receptor antibody and anti-platelet antibody associated with decreased platelet count. She completed the pregnancy with continuous intravenous administration of glucose that prevented hypoglycemia and finally delivered a healthy baby by Caesarian section. Both the hypoglycemia and thrombocytopenia, and the auto-antibodies disappeared after the delivery. We analyzed the patient's serum as a possible cause of hypoglycemia. Administration of the serum lowered blood glucose levels of mice more strongly than control serum. In addition, the serum phosphorylated tyrosine of insulin receptor of Chinese hamster ovary cells overexpressing human insulin receptors (CHO-IR cells) in vitro. These results suggest that multiple auto-antibodies might have been induced by a trigger of pregnancy, although the precise mechanism was unclear, and the anti-insulin receptor antibody and anti-platelet antibody might have induced hypoglycemia and thrombocytopenia, respectively, during the pregnancy.