Immunologic reactions to insulin: insulin allergy, insulin resistance, and the autoimmune insulin syndrome

Evolution of biosynthetic human insulin and its analogues for diabetes management

Hormones play a crucial role in maintaining the normal human physiology. By acting as chemical messengers that facilitate the communication between different organs, tissues and cells of the body hormones assist in responding appropriately to external and internal stimuli that trigger growth, development and metabolic activities of the body. Any abnormalities in the hormonal composition and balance can lead to devastating health consequences. Hormones have been important therapeutic agents since the early 20th century, when it was realized that their exogenous supply could serve as a functional substitution for those hormones which are not produced enough or are completely lacking, endogenously. Insulin, the pivotal anabolic hormone in the body, was used for the treatment of diabetes mellitus, a metabolic disorder due to the absence or intolerance towards insulin, since 1921 and is the trailblazer in hormone therapeutics. At present the largest market share for therapeutic hormones is held by insulin. Many other hormones were introduced into clinical practice following the success with insulin. However, for the six decades following the introduction the first therapeutic hormone, there was no reliable method for producing human hormones. The most common source for hormones were animals, although semisynthetic and synthetic hormones were also developed. However, none of these were optimal because of their allergenicity, immunogenicity, lack of consistency in purity and most importantly, scalability. The advent of recombinant DNA technology was a game changer for hormone therapeutics. This revolutionary molecular biology tool made it possible to synthesize human hormones in microbial cell factories. The approach allowed for the synthesis of highly pure hormones which were structurally and biochemically identical to the human hormones. Further, the fermentation techniques utilized to produce recombinant hormones were highly scalable. Moreover, by employing tools such as site directed mutagenesis along with recombinant DNA technology, it became possible to amend the molecular structure of the hormones to achieve better efficacy and mimic the exact physiology of the endogenous hormone. The first recombinant hormone to be deployed in clinical practice was insulin. It was called biosynthetic human insulin to reflect the biological route of production. Subsequently, the biochemistry of recombinant insulin was modified using the possibilities of recombinant DNA technology and genetic engineering to produce analogues that better mimic physiological insulin. These analogues were tailored to exhibit pharmacokinetic and pharmacodynamic properties of the prandial and basal human insulins to achieve better glycemic control. The present chapter explores the principles of genetic engineering applied to therapeutic hormones by reviewing the evolution of therapeutic insulin and its analogues. It also focuses on how recombinant analogues account for the better management of diabetes mellitus.

Cytotoxic T Cell Expression of Leukocyte-Associated Immunoglobulin-Like Receptor-1 (LAIR-1) in Viral Hepatitis C-Mediated Hepatocellular Carcinoma

Virus-related hepatocellular carcinoma (HCC) pathogenesis involves liver inflammation, therefore, despite successful treatment, hepatitis C virus (HCV) may progress to HCC from initiated liver cirrhosis. Cytotoxic T cells (Tcs) are known to be involved in HCV-related cirrhotic complications and HCC pathogenesis. The inhibitory checkpoint leukocyte-associated immunoglobulin-like receptor-1 (LAIR-1) is expressed on Tcs. Therefore, we aimed to determine whether the Tc expression level of LAIR-1 is associated with HCC progression and to evaluate LAIR-1 expression as a noninvasive biomarker for HCC progression in the context of liver cirrhosis related to HCV genotype 4 (G4) in Egyptian patients’ peripheral venous blood liquid biopsy. A total of 64 patients with HCC and 37 patients with liver cirrhosis were enrolled in this case-controlled study, and their LAIR-1 expression on Tc related to the progression of liver cirrhosis was examined and compared to that of the apparently healthy control group (n = 20). LAIR-1 expression was analyzed using flow cytometry. Results: The HCC group had significantly higher LAIR-1 expression on Tc and percentage of Tc positive for LAIR-1 (LAIR-1+Tc%) than the HCV G4-related liver cirrhosis group. LAIR-1+Tc% was correlated with the HCC surrogate tumor marker AFP (r = 0.367, p = 0.001) and insulin resistance and inflammation prognostic ratios/indices. A receiver operating characteristic (ROC) curve revealed that adding LAIR-1+Tc% to AFP can distinguish HCC transformation in the Egyptian patients’ cohort. Upregulated LAIR-1 expression on Tc could be a potential screening noninvasive molecular marker for chronic inflammatory HCV G4 related liver cirrhosis. Moreover, LAIR-1 expression on Tc may be one of the players involved in the progression of liver cirrhosis to HCC.

The effects of hyperinsulinemia on cochlear functions

CONTEXT

Hyperinsulinemia is the most common metabolic change associated with cochleovestibular diseases.

AIM

We aimed to investigate the auditory functions in hyperinsulinemic individuals.

SETTINGS AND DESIGN

A total of 164 patients were included in this case-control study. While 76 patients with insulin resistance (homeostasis model assessment of insulin resistance [HOMA-IR] of ≥2.5) constituted the case group, 88 patients with HOMA-IR values of <2.5 constituted the control group of the study.

MATERIAL AND METHODS

The 75 g oral glucose tolerance test, blood biochemistry tests, hormonal analysis, audiological assessment, electrocochleography (EcochG), and transient evoked otoacoustic emissions (TEOAE) testing were performed.

STATISTICAL ANALYSIS

One-way analysis of variance and Kruskal-Wallis analysis of variance were used for the comparison of the metabolic and ear parameters in the normal glucose tolerance (NGT), impaired fasting glucose (IFG), and impaired glucose tolerance (IGT) groups. The chi-square test was used to compare nominal variables. Spearman and Pearson correlation coefficients were used for the correlation analyses of continuous variables.

RESULTS

The pure tone audiometry at 0.5, 1, 2, and 4 kHz was better in the case group than in the control group. A positive correlation was found between HbA1c and right ear 0.5, 1, 4, and 8 kHz threshold values and left ear 2, 4, 6, and 8 kHz threshold values. A negative correlation was found between HbA1c and speech discrimination scores. The right ear 1.00 and 2.83 kHz TEOAE measurements in the individuals with NGT were found higher than those in patients with IGT, and the 1.42 kHz TEOAE measurements and reproducibility were found higher than those in patients with IFG. The left ear 1.00 and 1.42 kHz TEOAE measurements of the IGT patients were found lower than those of IFG and NGT patients.

CONCLUSION

We showed that hearing was worsening in hyperinsulinemic patients and prediabetic conditions were related to hearing function impairment.

Premature atherosclerosis in systemic sclerosis patients: Its relation to disease parameters and to traditional risk factors

AIM

To detect premature atherosclerosis in systemic sclerosis (SSc) patients and its relation to disease parameters and traditional risk factors.

METHOD

This study included 40 SSc patients and 40 healthy age and sex matched controls. All patients were subjected to full history taking, clinical examination, relevant laboratory and radiological investigations. Doppler ultrasonography (US) of the common carotid was performed to measure intima-media thickness (ccIMT) and Doppler US of the brachial artery was performed to measure flow mediated dilatation (FMD).

RESULTS

The mean value of ccIMT was 0.59 ± 0.2 mm in SSc patients and 0.51 ± 0.09 mm in controls and the difference was significant (P = 0.03). A statistically significant difference was found in mean brachial artery diameter before and after hyperemia, in flow change and in FMD between SSc patients and controls. ccIMT showed significant positive correlation with age, C-reactive protein (CRP), cholesterol, triglycerides and low density lipoprotein (P < 0.05). FMD showed significant positive correlation with daily dose of steroids (P = 0.04). Brachial artery diameter after hyperemia showed significant negative correlation with erythrocyte sedimentation rate (ESR). Peak systolic velocity before ischemia showed significant positive correlation with body mass index (BMI) and significant negative correlation with insulin level.

CONCLUSION

Our findings confirm the presence of premature atherosclerosis in SSc patients assessed by significant impairment of FMD, flow change and ccIMT, and it is associated with traditional cardiovascular risk factors such as age, dyslipidemia and obesity (BMI) as well as with the use of steroids and markers of inflammation such as CRP and ESR.

Severe Insulin-resistant Diabetes due to Insulin Antibodies Associated with Eosinophilia

A 66-year-old man with type 2 diabetes on hemodialysis treatment was admitted due to poor glycemic control. His serum insulin level and the (125)I-insulin binding rate were extremely high with an increased eosinophil count, although he did not have an allergic reaction to insulin or an elevation of specific IgE for human insulin. A Scatchard analysis revealed that the patient's insulin antibodies had a low affinity constant and a high binding capacity. Prednisolone administration decreased the eosinophil count and (125)I-insulin binding rate; accordingly, the glycemic control improved. Corticosteroid therapy may be a potent therapeutic strategy for insulin antibody-induced severe insulin resistance with eosinophilia.

Role of hyperinsulinemia in increased risk of prostate cancer: a case control study from Kathmandu Valley

AIM

To investigate the effect of hyperglycemia and hyperinsulinemia on prostate cancer risk.

MATERIALS AND METHODS

This hospital based study was carried out using data retrieved from the register maintained in the Department of Biochemistry of a tertiary care hospital of Kathmandu, Nepal between 31st December, 2011 and 31st October, 2013. The variables collected were age, serum cholesterol, serum calcium, PSA, fasting blood glucose, serum insulin. Analysis was performed by descriptive statistics and testing of hypothesis using Excel 2003, R 2.8.0, Statistical Package for the Social Sciences (SPSS) for Windows Version 16.0 (SPSS Inc; Chicago, IL, USA) and the EPI Info 3.5.1 Windows Version.

RESULTS

Of the total 125 subjects enrolled in our present study, 25 cases were of PCa and 100 were healthy controls. The mean value of fasting plasma glucose was 95.5 mg/dl in cases of prostatic carcinoma and the mean value of fasting plasma insulin was 5.78 μU/ml (p value: 0.0001*). The fasting insulin levels μU/ml were categorized into the different ranges starting from ≤2.75, >2.75 to ≤4.10, >4.10 to ≤6.10, >6.10μU/ml. The maximum number of cases of prostatic carcinoma of fasting insulin levels falls in range of >6.10μU/ml. The highest insulin levels (>6.10μU/ml) were seen to be associated with an 2.55 fold risk of prostatic carcinoma when compared with fasting insulin levels of (<2.75 μU/ml).

CONCLUSIONS

Elevated fasting levels of serum insulin appear to be associated with a higher risk of prostate cancer.

Clinical experience with U500 insulin: risks and benefits

OBJECTIVE

To describe our clinical experience with U500 insulin in insulin-resistant patients, including change in glucose control, body weight, insulin dose, and hypoglycemic episodes.

METHODS

In September 2010, we undertook a retrospective chart review of patients who had U500 insulin in their medication list in the preceding 2 years who were treated in the endocrinology section at Dartmouth Hitchcock Medical Center. Glycosylated hemoglobin (A1C), body weight, and insulin dosage were documented before U500 insulin introduction, after 6 months of U500 insulin use, and at the last clinic visit when the patient was still taking U500 insulin. Hypoglycemic episodes and number of daily injections were recorded.

RESULTS

Records of 53 patients were analyzed, one of the largest reports of U500 insulin use published to date. The mean A1C level decreased from 10.1% before U500 insulin was initiated to 9.1% after 6 months of U500 use to 8.6% at the last follow-up visit (mean follow-up was 36.6 ± 24 months). At the last charted visit, body weight increased by a mean of 6.8 kg and insulin dosage increased by a mean of 0.44 units/kg. We observed a significant increase in the number of nonsevere hypoglycemic episodes and a decrease in the number of daily injections.

CONCLUSION

Patients with uncontrolled, severely insulin-resistant diabetes can be satisfactorily treated with U500 insulin with the potential to improve glycemic control. An increase in body weight, insulin dosage, and the number of nonsevere hypoglycemic episodes was observed.

The effects of anti-insulin antibodies and cross-reactivity with human recombinant insulin analogues in the E170 insulin immunometric assay

BACKGROUND

Insulin assays are affected by varying degrees of interference from anti-insulin antibodies (IAs) and by cross-reactivity with recombinant insulin analogues. We evaluated the usefulness of the E170 insulin assay by assessing IA effects and cross-reactivity with 2 analogues.

METHODS

Sera were obtained from 59 type 2 diabetes patients receiving continuous subcutaneous insulin infusion and 18 healthy controls. Insulin levels were determined using an E170 analyzer. To investigate the effects of IAs, we performed IA radioimmunoassays, and analyzed the differences between directly measured insulin (direct insulin) and polyethylene glycol (PEG)-treated insulins (free, IA-unbound; total, IA-bound and unbound insulin). We performed in-vitro cross-reactivity tests with insulin aspart and insulin glulisine.

RESULTS

In IA-positive patients, E170 free insulin levels measured using the E170 analyzer were significantly lower than the direct insulin levels. The mean value of the direct/free insulin ratio and IA-bound insulin, which were calculated as the difference between total and free insulin, increased significantly as endogenous IA levels increased. The E170 insulin assay showed low cross-reactivities with both analogues (< 0.7%).

CONCLUSIONS

IAs interfered with E170 insulin assay, and the extent of interference correlated with the IA levels, which may be attributable to the increase in IA-bound insulin, and not to an error in the assay. The E170 insulin assay may measure only endogenous insulin since cross-reactivity is low. Our results suggest that the measurement of free insulin after PEG pre-treatment could be useful for beta cell function assessment in diabetic patients undergoing insulin therapy.

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.

Insulin allergy: clinical manifestations and management strategies

Insulin allergy in patients with diabetes mellitus on insulin treatment is a rare condition. It is suspected upon noticing immediate symptoms following insulin injections. The immediate vital implications for the patient call for prompt diagnosis and management of insulin allergy. We review current knowledge and procedures based on four diabetic patients who presented in our clinic. Insulin allergy was suspected as they showed immediate symptoms after insulin injection (urticaria, rash, angioedema, hypotension, dyspnea). A detailed allergologic work-up was performed and adequate therapy was initiated. In three of the four patients, a specific immunotherapy was started whereas in one patient a switch to oral antidiabetics was possible and consequently initiated. By standard prick testing and measurement of specific IgE antibodies, a type 1 IgE-mediated allergy was confirmed. After initiation of insulin immunotherapy, the symptoms completely resolved in two out three of patients and significantly improved in the third patient. The fourth patient was successfully switched to oral antidiabetics. Insulin allergy is a rare but severe condition that calls for immediate allergological work-up. It can be managed well in close cooperation between the diabetologist and the allergologist. Specific immunotherapy is efficient and should be considered.

Insulin administration may trigger pancreatic beta-cell destruction in patients with type 2 diabetes

Insulin administration causes various types of immune response to insulin. However, there have been no reports that insulin administration triggers pancreatic beta-cell destruction in diabetic patients. We evaluated three patients who had suffered from type 2 diabetes or impaired glucose tolerance for 5-30 years. After an episode of diabetic mononeuropathy or poor glycemic control, they started human insulin therapy. All the patients' serum or urinary C-peptide levels were preserved before insulin therapy, whereas within a few months they rapidly declined to below detection limits. A high titer of insulin antibody was detected at or after the development of insulin deficiency. Shortly after the initiation of insulin therapy, two of the patients developed an insulin allergy. Autoantibodies to GAD65 or IA-2 were negative throughout the clinical course in two cases, but transiently positive in one case. In a histological examination of pancreas tissue obtained by a pancreatic biopsy in one case, mononuclear cell infiltration into the islets was observed. They all had a type 1 diabetes high-risk HLA class II haplotype in Japanese, and class I alleles of the insulin gene VNTR. The above findings suggest that insulin administration may have triggered pancreatic beta-cell destruction in these patients.

Immunological responses to exogenous insulin

Regardless of purity and origin, therapeutic insulins continue to be immunogenic in humans. However, severe immunological complications occur rarely, and less severe events affect a small minority of patients. Insulin autoantibodies (IAAs) may be detectable in insulin-naive individuals who have a high likelihood of developing type 1 diabetes or in patients who have had viral disorders, have been treated with various drugs, or have autoimmune disorders or paraneoplastic syndromes. This suggests that under certain circumstances, immune tolerance to insulin can be overcome. Factors that can lead to more or less susceptibility to humoral responses to exogenous insulin include the recipient's immune response genes, age, the presence of sufficient circulating autologous insulin, and the site of insulin delivery. Little proof exists, however, that the development of insulin antibodies (IAs) to exogenous insulin therapy affects integrated glucose control, insulin dose requirements, and incidence of hypoglycemia, or contributes to beta-cell failure or to long-term complications of diabetes. Studies in which pregnant women with diabetes were monitored for glycemic control argue against a connection between IAs and fetal risk. Although studies have shown increased levels of immune complexes in patients with diabetic microangiopathic complications, these immune complexes often do not contain insulin or IAs, and insulin administration does not contribute to their formation. The majority of studies have shown no relationship between IAs and diabetic angiopathic complications, including nephropathy, retinopathy, and neuropathy. With the advent of novel insulin formulations and delivery systems, such as insulin pumps and inhaled insulin, examination of these issues is increasingly relevant.

Allergy reactions to insulin: effects of continuous subcutaneous insulin infusion and insulin analogues

The purification of animal insulin preparations and the use of human recombinant insulin have markedly reduced the incidence but not completely suppressed the occurrence of insulin allergy manifestations. Advances in technologies concerning the mode of delivery of insulin, i.e. continuous subcutaneous insulin infusion (CSII), and the use of insulin analogues, resulting from the alteration in the amino acid sequence of the native insulin molecule, may influence the immunogenicity and antigenicity of native insulin. Instead of increasing allergy reactions, CSII has been reported to represent a successful alternative treatment in diabetic patients presenting local or generalized allergy to insulin or other components (zinc, protamine) of conventional treatment. Most recent reports concern CSII-treated patients using short-acting insulin analogues (essentially insulin lispro), although the precise role of these insulin analogues remains unclear as allergy to them has also been described. Finally, data on antigenicity and immunogenicity of long-acting insulin analogues (glargine, detemir), which may mimic the basal insulin delivery with CSII, remain scarce at present.

Lipodystrophy reactions to insulin: effects of continuous insulin infusion and new insulin analogs

Management of diabetes mellitus can be responsible for cutaneous adverse events. For example, lipoatrophy or lipohypertrophy can develop at the site of insulin injections. Lipohypertrophy remains a frequent complication of insulin therapy irrespective of the insulin source and mode of administration. Lipoatrophy at insulin injection sites is considered to be an immune complex-mediated inflammatory lesion; however, it has become a rare event since the advent of human insulin. Nowadays, continuous subcutaneous insulin infusion (CSII) using a portable pump and/or injections of insulin analogs with an altered amino acid sequence compared with native insulin may cause lipodystrophy in diabetic patients. Some case reports describe the recovery of lipoatrophy following the use of CSII and/or short-acting insulin analogs. Conversely, exceptional cases of lipoatrophy have occurred in patients receiving lispro insulin analog via CSII. Lipodystrophy reactions remain a potential problem when managing diabetic patients with new insulin therapy technologies.

Immunogenic and allergenic potentials of natural and recombinant innocuous proteins

A new aspect of protein immunogenic and allergenic properties has become important recently, when there is a higher chance that our immune system will be exposed to novel protein antigens and/or familiar protein antigens with an unprecedented high frequency and large amount. These proteins are innocuous, nontoxic, and noninvasive by themselves, and include various natural proteins from the environment and recombinant proteins from industry. The technical term allergenic has been used for such proteins and their abilities to induce specific IgE production and to cross-link IgE/Fc epsilonRI on the surface of mast cells and basophiles have been recognized. As for the environmental proteins, some physicochemical properties (solubility, stability, and permeability across a mucosal epithelium) of the proteins indirectly play important roles in their allergenic potential because they do not originate from invasive pathogens as vehicles. Indeed, several lines of experimental evidences have been accumulated indicating that all proteins are absorbed across mucosal epithelia by transcellular transport and/or through interstitial spaces among the epithelial cells but not at equal levels. Some animal models have been established for natural sensitization to some allergenic proteins by feeding or intragastric administration without an adjuvant and, in a few cases, some symptoms resembling human allergy and even anaphylaxis have been induced by oral challenge with the proteins. Sometimes, even to self-proteins, the immunogenic or allergenic potential is given by post-translational modifications and possibly by unknown structural/conformational alterations, when they are exogenous self-proteins, such as recombinant human proteins for drug use. Despite the accumulation of knowledge and the progress in analytical technology on protein allergenicity, it is still crucial to predict the allergenic potential of novel and unused proteins. However, some animal models are applicable for assessing the relative allergenic potential of processed proteins in comparison with that of native proteins in preclinical studies.

Statin use in the metabolic syndrome

The metabolic syndrome is a condition associated with obesity, insulin resistance, hypertension, dyslipidemia, hypercoagulability, and chronic inflammation, all of which increase the risk of cardiovascular disease (CVD). The Third National Cholesterol Education Program Adult Treatment Panel extensively discussed the metabolic syndrome because it is a major health issue in the United States due to the national epidemic of obesity. Statins cause significant CVD risk reduction in patients with the metabolic syndrome by alterations in lipid levels and possibly by decreasing inflammation. Because of the increased CVD risk associated with the metabolic syndrome and extensive clinical trial evidence documenting reduction of CVD risk with statin treatment, all patients with the metabolic syndrome should be evaluated as candidates for statin treatment as part of a multidisciplinary approach to reduce CVD risk.

Insulin-specific tolerance in diabetes

At present it is possible to predict the development of type 1A diabetes (immune-mediated diabetes) in man and prevent the disorder in animals. Studies of immunity to insulin play a prominent role in both disease prediction and disease prevention. For both man and the NOD mouse, insulin autoantibodies usually precede the development of diabetes and can be utilized to assist in disease prediction. T cells clones recognizing insulin, both CD4 and CD8, can transfer disease to young mice or immunodeficient animals. Specific insulin peptides reacting with these clones have been identified, their crystal structure when bound to a human "diabetogenic" MHC allele has been determined, and specific peptides can be used either to induce or to prevent disease. Clinical trials of both insulin and an altered peptide ligand of insulin to prevent islet beta-cell destruction are underway. Insulin is one of a number of islet autoantigens, but it is likely that immune responses to insulin will be central to both pathogenesis and immunologic protection.

Human immune response to recombinant human proteins

Delivery of pharmacological doses of proteins to people has raised concerns of inducing immune responses, especially when the protein is provided in multiple doses over an extended period of time. Immune responses could impact the therapeutic exposure and efficacy of the protein itself. In addition, there have been fears of anaphylaxis or autoimmunity. This review summarizes the available literature regarding the measurement and evaluation of immune responses observed during clinical assessment of recombinant human proteins. Immune responses have ranged from none at all to inactivation and/or accelerated clearance. Presence of antibodies does not necessarily impact therapeutic viability. While responses are related to frequency and route of delivery, there is no clear relationship that enables one to predict the clinical experience.

Development and use of enzyme-linked immunosorbent assays (ELISA) for the detection of protein aggregates in interferon-alpha (IFN-alpha) formulations

PURPOSE

Protein aggregates are thought to be involved in the immunogenicity of recombinant proteins in humans. To probe human IFN-alpha formulations for the presence of soluble protein aggregates, enzyme-linked immunosorbent assays (ELISA) were developed.

METHODS

For the detection of IFN-alpha-IFN-alpha and HSA-IFN-alpha aggregates, sandwich ELISAs were developed using a monoclonal anti-IFN-alpha antibody as a capture antibody and the same anti-IFN-alpha antibody and an anti-human serum albumin (HSA) antibody (HRP-labeled), respectively.

RESULTS

Marketed freeze-dried, HSA-containing IFN-alpha-formulations tested in the ELISAs all contained IFN-alpha-IFN-alpha and/or HSA-IFN-alpha protein aggregates, although in varying amounts. These aggregates were predominantly IFN-alpha dimers and 1:1 conjugates of HSA with IFN-alpha. Test formulations revealed that aggregation of IFN-alpha was strongly affected by the presence of pharmaceutical excipients, pH of the formulation, lyophilisation procedure, and storage temperature and time.

CONCLUSIONS

The ELISAs are rapid, highly specific for aggregates in the presence of both IFN-alpha and HSA monomers and allow the direct detection of both types of aggregates in formulations in the nanogram range. The new assays will assist the monitoring of the aggregate-inducing processes during IFN-alpha formulation and storage in an early phase and the development of aggregate-free IFN-alpha formulations.

Protein aggregates seem to play a key role among the parameters influencing the antigenicity of interferon alpha (IFN-alpha) in normal and transgenic mice

PURPOSE

During long-term treatment of various malignant or viral diseases with IFN-alpha up to 20% of patients develop anti-IFN-alpha antibodies for as yet unknown reasons.

METHODS

To address this issue, a mouse model using Balb/C mice was established and the relevance of several potentially anti-IFN-alpha antibodies inducing factors was studied.

RESULTS

The model revealed that both a higher frequency of injections and a higher dosage of IFN-alpha were more immunogenic and that the route of administration affected the antibody response to IFN-alpha. The intrinsic immunostimulatory activity of IFN-alpha itself also enhanced the immune response. IFN-alpha protein aggregates (IFN-alpha-IFN-alpha and human serum albumin (HSA)-IFN-alpha aggregates), which were recently identified in all marketed IFN-alpha products, were significantly more immunogenic than IFN-alpha monomers. These aggregates broke the tolerance against human IFN-alpha monomers in human IFN-alpha transgenic mice.

CONCLUSIONS

Based on these animal studies it is proposed that the immune response to IFN-alpha in humans is most probably elicited by a combination of several factors among which IFN-alpha protein aggregates seem to play a key role.

Medical history risk factors for non-Hodgkin's lymphoma in older women

BACKGROUND

It has been suggested that certain medical conditions and drug exposures might suppress the immune system and increase the risk of developing non-Hodgkin's lymphoma (NHL).

PURPOSE

We investigated whether specific medical conditions and drug exposures were associated with the risk of NHL in a cohort of older women who were enrolled in the Iowa Women's Health Study.

METHODS

A cohort of 41837 women, 55-69 years of age at baseline, was followed prospectively for the development of cancer from 1986 through 1992. These women had completed a baseline questionnaire in January 1986 that inquired about the occurrence and age at onset of specific medical conditions, about family history of cancer, and about the use of selected medications. Follow-up questionnaires were mailed to the women in 1987, 1989, and 1992. Incident cancers and deaths were ascertained through linkages to state and national databases. For most analyses, women with a self-reported history of cancer at baseline (n = 3903) were excluded. Relative risks (RRs) and 95% confidence intervals (CIs), adjusted for age or for age and other variables, were used as a measure of the association between NHL and medical history factors. Reported P values are two-sided.

RESULTS

One hundred fourteen incident cases of NHL were identified in the cohort during follow-up. A history of adult-onset diabetes mellitus (i.e., first diagnosed after the age of 30 years) was associated with an increased risk of developing NHL (age-adjusted RR = 2.18; 95% CI = 1.22-3.90). In addition, there was an association between the duration of adult-onset diabetes and increasing risk of NHL (P for trend = .004), with an age-adjusted RR of 2.90 (95% CI = 1.07-7.90) for women with a diagnosis of diabetes for 15 or more years compared with women with no diagnosis of diabetes. Women with a history of blood transfusion were also at increased risk for the development of NHL (age-adjusted RR = 1.95; 95% CI = 1.33-2.85). The risk estimates for diabetes and transfusion history were independent of each other and were not changed substantially after adjustment for other risk factors. History of a previous cancer (excluding hematopoietic and lymphatic cancers) was associated with an increased risk of NHL (age-adjusted RR = 1.92; 95% CI = 1.21-3.06); this risk estimate was attenuated somewhat after adjustment for a history of diabetes, transfusion history, and other major risk factors (RR = 1.66; 95% CI = 1.02-2.69). No statistically significant associations were found between NHL and a history of chronic colitis, nonestrogen steroid use, use of exogenous estrogens, or use of thyroid medications.

CONCLUSIONS AND IMPLICATIONS

A history of adult-onset diabetes mellitus, blood transfusion, and a history of cancer (or its treatment) appear to be independent risk factors for NHL in older women.

Systemic allergy to endogenous insulin during therapy with recombinant DNA (rDNA) insulin

BACKGROUND

Clinically significant allergic reactions with insulin therapy are known to occur. There have been rare reports of allergic reactions to endogenously secreted insulin manifested as insulin resistance. No reports of systemic or local allergic reactions to endogenous insulin have previously been cited, and no immunologic reactions to endogenous insulin have been reported during therapy with recombinant (rDNA) insulin.

METHODS

We report a case in which the patient, a 28-year-old black woman who initially presented with gestational onset diabetes but postpartum continued to require insulin, developed generalized allergic reactions during therapy with subcutaneously injected rDNA insulin. Similar reactions occurred with sulfonylurea therapy. She was unable to tolerate any pharmacologic therapy for diabetes without concurrent use of at least 10 mg of prednisone per day.

RESULTS

Skin testing with the insulin preparations were positive, while skin testing to the sulfonylurea hypoglycemic agents were negative. IgE antibodies to insulin where present in high titer. Oral challenge to sulfonylurea hypoglycemic agents produced generalized urticarial reactions coinciding with time of peak insulin secretion. Oral challenge to other medications containing sulfa produced no adverse reaction. Biphasic hypersensitivity reactions occurred during attempts at desensitization which were futile without simultaneous glucocorticoid therapy.

CONCLUSIONS

This is the first report of local and systemic allergic reactions to endogenously secreted insulin in association with rDNA insulin therapy. Although immunologic complications with rDNA therapy appear less frequently than with insulin preparations, this case illustrates the need for continued awareness for potential allergic complications occurring with rDNA insulin therapy.

Primary systemic allergy to human insulin: recurrence of generalized urticaria after successful desensitization

Primary systemic allergy to human insulin is rare. We report a case of recurrent immediate local reactions followed eventually by generalized urticaria to recombinant human insulin (Humulin) in an insulin-dependent diabetic. Skin test to Humulin R was positive, and the patient was successfully desensitized using a modified rapid desensitization protocol. Two weeks later, he had another episode of generalized urticaria after Humulin R injection. His treatment was resumed at a lower dose, and within a week he was able to tolerate his usual regimen of insulin. To our knowledge, this is the first report of a recurrence of systemic reaction after successful desensitization.

A case of primary and generalized allergy to human insulin with no history of any prior insulin exposure

A generalized hypersensitivity reaction against human insulin was demonstrated in a non-insulin dependent diabetic man treated with only human insulin. The patient had no history of previous insulin exposure or atopy. Because of negative reactions to intracutaneous tests of constituents of the formulation and the presence of insulin-specific IgE antibody, this generalized allergic reaction seems to have been caused by the human insulin itself. Although desensitization was not effective, this allergic reaction was improved both by the treatment with oral antihistamines and desensitization. Cases of generalized and primary allergy against human insulin have been rarely reported making this a very rare case.

Mechanisms of hormone resistance: lessons from insulin-resistant patients

Hormones are secreted by endocrine glands and transported to the target cell at which the hormone acts. The hormone binds to its receptor, thereby eliciting various biological responses within the target cell. Examples of disease mechanisms that function at the different stages in the development of the insulin receptor, and result in insulin resistance, are discussed in this review. Antibodies to insulin can impair delivery of the hormone to the target cell, and can desensitize that target cell to insulin action. In recent years, several genetic diseases have been identified that result from mutations in the genes encoding the relevant receptors. Studies of syndromes of insulin resistance provide illustrations of the multiple types of defects in receptor function that can generally cause hormone resistance (12, 13). For example, mutations in the receptor can decrease the number of receptors on the cell surface by inhibiting receptor biosynthesis, impairing receptor transport to the cell surface, or accelerating the rate of receptor degradation. Alternatively, mutations have been identified that decrease the affinity of insulin binding or inhibit receptor tyrosine kinase activity. In recent years, there has been considerable progress toward elucidating post-receptor mechanisms in the biochemical pathways of hormone action. At present, there are a limited number of examples of mutations in genes encoding proteins that function in this part of the pathway, but it seems likely that additional examples will be discovered in the future. It is likely that these insights into biochemical mechanisms of disease will ultimately lead to an improvement in our ability to treat human disease.

Fine-tuning insulin therapy

It is now possible to mimic normal insulin action more precisely than ever before with physiologic treatment programs using self-monitoring of blood glucose levels and newer insulins with more predictable action. Physiologic programs are more effective for both insulin-dependent (type I) and non-insulin-dependent (type II) diabetes mellitus. With type I diabetes, conventional fixed-dose programs are often quite effective, but some patients may prefer the greater flexibility of intensive insulin therapy. Studies are under way that should provide further guidance on use of intensive insulin therapy. The decade of the 1990s should see additional improvements in insulin preparations and in methods of delivery and monitoring, so that patients can be treated with programs that are not only safer but more physiologic, more comfortable, and more effective in maintaining long-term good health.

A case of insulin allergy: the crystalline human insulin may mask its antigenicity

We report an unusual case of insulin allergy. A 48-year-old man with non-insulin-dependent diabetes mellitus receiving biosynthetic isophane human insulin (Humulin N) developed itchy wheal-and-flare reactions at the sites of injection. When Humulin N was changed to a semi-synthetic crystalline human insulin zinc (Novolin U), the allergic reactions completely disappeared. Evaluation of his serum showed a high level of insulin-specific IgE. Skin testing with all commercially available insulins showed immediate local reactions to all agents tested except for Novolin U. In addition, decrystallized Novolin U prepared by lowering the pH with acetic acid also induced a positive reaction. These observations suggest that the crystallized structure of human insulin may mask its antigenicity for allergic reactions.

Altered processing of human insulin by B lymphocytes from an immunologically insulin-resistant type I diabetic patient

Immunologically insulin resistant (IIR) type I diabetic patients possess significantly elevated levels of anti-insulin serum autoantibodies. We investigated whether altered insulin processing by B lymphocytes contributes to this form of insulin resistance. A comparison was made of the 125I-labelled human insulin (HI) peptides processed by Epstein-Barr virus (EBV)-transformed B lymphocytes derived from HLA-identical and nonidentical IIR with non-IIR type I diabetic patients on insulin therapy and healthy non-diabetic individuals. Several peptides detected in the extracellular, membrane-associated and intracellular compartments of B cells from an IIR type I diabetic patient differed from those found in the corresponding compartments of B cells from two non-IIR type I diabetic patients and two normal individuals. These data suggest that HI is processed differently by B cells from an IIR type I diabetic patient compared with B cells from non-IIR type I diabetic patients and normal individuals. Further, we found that two of the five plasma-membrane associated processed HI peptides on the IIR patients' B cells were absent from the membrane compartments of the other B cell lines examined. Thus, it is possible that one or both of these peptides, unique to the IIR patient's B cells, consist of an immundominant epitope(s) that stimulates the production of insulin autoantibodies which mediate the onset of IIR in type I diabetes.

The effects of insulin antibodies during diabetic pregnancy on newborn infants

Levels of insulin antibody, free insulin, and total insulin in the blood of diabetic mothers and their newborn infants were measured, and the relations of these findings to perinatal complications were studied. The subjects were 35 patients: 8 treated with bovine/porcine insulin, 15 with porcine, and 12 with human insulin. Insulin antibody levels (insulin binding capacity; IBC) in patients injected with bovine/porcine insulin were higher. There was no difference in the insulin antibody levels between the groups treated with porcine and human insulin preparations. Infant insulin antibody levels were close to the mother's levels. Free insulin levels did not correlate with total insulin nor antibody levels, but correlated with plasma glucose levels in the infants. The birth weight did not correlate with insulin antibody levels. The frequency of neonatal hypoglycemia and cord hematocrit levels were increased when the mother's insulin antibody levels were over 20%. We conclude the following: 1) Insulin antibodies are transferred through the placenta; 2) The risk of neonatal hypoglycemia is high if the mother's insulin antibody levels are high; 3) Bovine insulin preparations should not be used.

Sulfated beef insulin treatment elicits CD8+ T cells that may abrogate immunologic insulin resistance in type I diabetes

The in vitro responses of T cells from 13 insulin-nonresistant and 1 immunologically insulin-resistant (IIR) type I diabetes patients to sulfated beef insulin (SBI) were analyzed. Insulin A-loop specific CD4+ T cells from these patients did not respond to SBI. After 1 yr of treatment with SBI the IIR patient's T cell and antibody responses to beef, pork, and human insulin progressed from very high to nondetectable levels. This occurred in parallel to the appearance of her insulin-specific CD8+ T cells, which inhibited the response of her A-loop-specific CD4+ T cells to insulin. A transient increase in her CD8+ anti-insulin antibody activity coincided with a relative lack of her CD8+ T cell activity. CD8+ T cells that regulate T cell responsiveness to insulin are probably present but difficult to detect in most type I diabetes patients. These T cells were identified in only 2 of 13 insulin-nonresistant patients who presented with lipoatrophy and insulin allergy, respectively, and who possessed high-titered, anti-insulin antibodies. Our data demonstrate that CD8+ T cells play an important role in controlling peripheral tolerance to insulin and may abrogate IIR in a diabetic patient treated with SBI.

Insulin pharmacology

Insulin initially became available for therapy in the 1920s. Over the years, a variety of insulin preparations have been formulated; preparations differ on the basis of purity, species of origin, and time course of action. Currently, highly purified preparations of human insulin are available with a variety of profiles of action.

Endocrine-skin interactions. Cutaneous manifestations of pituitary disease, thyroid disease, calcium disorders, and diabetes

Endocrinologic disorders occasionally manifest themselves by their associated or induced cutaneous abnormalities. In some instances the initial and most prominent complaints of the patient are related to alterations in the skin, and thus the dermatologist will at times be the first physician consulted. In this article we describe the cutaneous lesions that occur in patients with acromegaly, hypopituitarism, hypothyroidism, hyperthyroidism, diabetes mellitus, glucagonomas, hypercalcemia, hypoparathyroidism, and fibrous dysplasia. In addition, we also discuss the role of the skin in vitamin D metabolism. Whenever possible and where known, we have attempted to point out the pathophysiologic mechanisms that account for the cutaneous changes.

Assessment of the antigenic response in humans to a recombinant mutant interferon beta

Cancer patients were given a recombinant mutant interferon beta by alternating IM and IV injections with weekly escalation of doses from 0.1 to 400 million U. Antibodies specific to the interferon of the IgG class were detected in 24 of 30 patients using an indirect enzyme-linked immunosorbent assay. Serum from only 1 of the 30 patients had detectable ability to neutralize interferon biological activity. The in vivo interferon serum level, assayed as antiviral activity immediately after IV injection, was not lower than levels seen in the absence of antibodies. Antibodies did not alter the kinetics of clearance of interferon from the serum after IV administration. Antibody levels progressively decreased when interferon administration was discontinued. In most patients antibody levels decreased during a maintenance period when interferon was being administered only by the IV route. In a subsequent trial interferon was given IV, and antibody developed in only 2 of 36 patients. In contrast, in a trial in which interferon was given IM, 20 of 25 patients developed antibody. No antibody-related clinical sequelae could be detected in any of these patients.

A case of diabetes mellitus associated with anti-insulin autoantibodies without previous insulin injection

A case of diabetes mellitus who had high levels of fasting immunoreactive insulin (IRI) and low levels of immunoreactive C-peptide (CPR) is reported. Examination of her serum disclosed the presence of IgG class k + lambda type anti-insulin autoantibodies. She has never been treated with insulin, nor had drugs which have been reported to be responsible for inducing insulin autoimmune syndrome. Despite the presence of autoantibodies against insulin, she has never experienced hypoglycemia. Significance of the production of autoantibodies against insulin and physicochemical parameters of anti-insulin antibodies in her serum are discussed.

Antibodies to pancreatic hormones in diabetics treated before 1964 and after 1974

The prevalence and titer of antibodies to pancreatic hormones in 21 diabetics treated with USP insulin preparations before 1964 (Group 1) and in another 21 diabetics treated with more highly purified insulin preparations after 1974 (Group 2) were determined. All subjects in Group 1 had antibodies to insulin, 11 had antibodies to pancreatic polypeptide (PP) and 3 to glucagon. In Group 2, 17 had antibodies to insulin, 5 to PP, and 1 to glucagon. Antibodies to somatostatin (SRIF) were not detectable in either group. Group 1 subjects had higher titers of antibodies to insulin, glucagon, and PP than Group 2 subjects. Of note, the Group 1 subjects with the highest insulin antibodies also had the greatest prevalence and highest titers of antibodies to glucagon and PP. In order to address the question of possible differences in immune responsivity between Group 1 and 2 subjects, antibody titers to 4 ubiquitous viral agents were determined. There was no significant difference in viral antibody titers between the groups.

Mechanisms of insulin resistance in non-insulin-dependent (type II) diabetes

Characteristic of both obesity and non-insulin-dependent diabetes mellitus, insulin resistance is triggered at the level of the target tissue and can be induced by three general categories of causes: (1) an abnormal beta cell secretory product, (2) circulating insulin antagonists, or (3) a target tissue defect in insulin action. Decreased numbers of insulin receptors and a post-receptor defect in insulin action both play relative roles in insulin resistance. A general trend, however, indicates that as insulin resistance increases, the post-receptor defect becomes more prominent. Impaired glucose uptake and subsequent increased hepatic glucose oxidation in non-insulin-dependent diabetes mellitus are major contributing factors to fasting hyperglycemia.

Differing effects of antiinsulin serum and antiinsulin receptor serum on 123I-insulin metabolism in rats

Anesthetized rats were treated with saline, antiinsulin receptor serum, or antiinsulin serum, and the biodistribution of high pressure liquid chromatography-purified 123I-Tyr A14-insulin was studied by scintillation scanning. Time activity curves over organs of interest were calibrated by sacrificing the rats at the end of the experiment and directly determining the radioactivity in the blood, liver, and kidneys. Saline-treated rats exhibited normal insulin biodistribution. The highest concentration of 123I-insulin was found in the liver, and reached 30% of total injected dose between 3 and 5 min after injection. After this peak, activity rapidly decreased with a t1/2 of 6 min. Activity of 123I-insulin in kidney showed a more gradual rise and fall and was approximately 15% of injected dose at its maximum. In rats treated with antiinsulin antiserum, insulin biodistribution was markedly altered. Peak liver activity increased with increasing antibody concentration with up to 90% of injected dose appearing in the liver. In addition, there was no clearance of the liver 123I-insulin over 30 min. Autoradiographic studies demonstrated that in contrast to the normal rats in which radioactivity was associated with hepatocytes, in rats passively immunized with anti-insulin serum, 125I-insulin was associated primarily with the Kuppfer cells. In contrast, antibodies to the insulin receptor markedly inhibited 123I-insulin uptake by the liver. Kidney activity increased, reflecting the amount of free 123I-insulin that reached this organ. This is similar to the pattern observed when insulin receptors are saturated with a high concentration of unlabeled insulin. Thus, both insulin antibodies and anti-receptor antibodies alter the distribution of insulin, but with very different patterns. The use of 123I-insulin and scintillation scanning allows one to study specific alterations in insulin distribution in animal models of insulin-resistant states, and should also be useful in human disease states.

Cutaneous manifestations of diabetes mellitus in children

This article reviews skin changes occurring in diabetic children. Skin changes may be related to metabolic alterations associated with diabetes. Others may be manifestations of macro or microvascular disease. Insulin injections, required for management of most diabetes in the pediatric age group, may also cause cutaneous changes. There remain several cutaneous abnormalities which are observed with increased frequency among diabetics, the significance of which is unknown. The skin is a potentially invaluable tool for understanding certain diabetic complications; however, the value of observations and experimental data relating to cutaneous changes in diabetics depends upon documentation of the type of diabetes mellitus employing the currently accepted classification system.