Immunopathology of immune-mediated (type 1) diabetes

Immune-mediated diabetes is established as an autoimmune disease, which most often is induced during late infancy or early childhood. Multiple genetic lesions in immune tolerance are required before autoimmunity can be sustained once induced by environmental agents, such as viruses. The diagnostic hallmarks of the disease are the islet autoantibodies, which should be made routinely available to physicians to distinguish this disease from other forms of diabetes. The ability to identify individuals with impending IMD and those at high risk of IMD lends itself to the development of clinical trials to prevent diabetes by immunologic means. We believe that this will soon be possible with the development and use of vaccines.     

Multiple endocrine neoplasia type 1 (MEN1) in Austria

Multiple endocrine neoplasia type 1 (MEN1) is a rare cancer predisposition syndrome. It results from the autosomal dominant inheritance of inactivating germ-line mutations of the MEN1 tumor suppressor gene. Mutation carriers are prone to develop tumors, preferentially, of the parathyroid and anterior pituitary glands as well as the enteropancreatic endocrine tissues. Because such tumors also occur without the MEN1 context, we have set up a molecular genetic screening program in Austria to discriminate between heritable and non-heritable tumor forms. Following the recognition of a MEN1-specific germ-line mutation in a tumor patient, we extend the screening to all first-degree relatives. To date, we have studied 42 individuals by sequencing the coding exons 2 to 10 of the MEN1 gene. A germ-line mutation was discovered in four of seven families suspected, clinically, to have MEN1, and in 3 of 22 (13.6%) patients with a presumed sporadic endocrine tumor. The respective mutations were also detected in three first-degree relatives of whom only one 6-year-old boy was asymptomatic at the time of investigation. The possibility to clearly discriminate between genetically predisposed and non-predisposed individuals has a significant impact on the diagnosis and clinical management of both patients and their relatives. Both symptomatic and asymptomatic mutation carriers can be closely monitored, thereby allowing early recognition and treatment of developing tumors. Non-affected relatives, on the other hand, do not require further controls. Finally, this approach also provides the information necessary for reliable genetic counseling.     

Hyperproinsulinemia segregates young adult patients with newly diagnosed autoimmune (type 1) and non-autoimmune (type 2) diabetes

OBJECTIVE: To investigate whether measurements of proinsulin and/or intermediate proinsulin degradation products could be used to differentiate between autoimmune (type 1) and non-autoimmune (type 2) diabetes in young adults. MATERIAL AND METHODS: Total proinsulin, intact proinsulin and 32,33 split proinsulin concentrations were measured in 25 patients aged 15-34 years with type 1 diabetes, as defined by the presence of at least two positive islet autoantibodies, and in 23 antibody-negative patients of similar age with type 2 diabetes, at the time of clinical onset of diabetes and at 3-4 months thereafter. Comparisons were made with data from 25 healthy subjects matched for gender and age. RESULTS: Plasma levels of total proinsulin, intact proinsulin and 32,33 split proinsulin were significantly increased 2-3-fold in the patients with newly diagnosed type 2 diabetes as compared with the controls, both in absolute terms (p<0.0001) and when related to circulating insulin (p<0.01-0.0002). In contrast, absolute proinsulin and 32,33 split proinsulin concentrations were significantly lower in patients with onset of type 1 diabetes than in controls. When proinsulin and split proinsulin release were related to plasma insulin, however, similar ratios were found in the type 1 diabetes patients and in controls. Using the 90th percentile for total proinsulin in the control group as the cut-off, the sensitivity and specificity for differentiation between autoimmune and non-autoimmune diabetes were 87% and 92%, respectively. At 3-4 months after clinical onset of diabetes, proinsulin secretion was still 2-3 times higher in type 2 than in type 1 diabetes patients (p<0.001). CONCLUSIONS: Young adult patients with newly diagnosed type 2 diabetes display disproportionate hyperproinsulinemia, whereas proinsulin secretion appears to be normal in patients with clinical onset of type 1 diabetes. Evaluation of proinsulin and 32,33 split proinsulin concentrations may be useful as a diagnostic tool in differentiating between autoimmune and non-autoimmune diabetes in young adults, particularly in those lacking islet autoantibodies at diagnosis.     

Collagen binding activity in sera of patients with insulin-dependent (type 1) and non insulin-dependent (type 2) diabetes mellitus

An increase in the capacity of serum IgG to bind to native type IV collagen was observed in patients with both insulin-dependent and non insulin-dependent diabetes mellitus. This increased binding seems to be due to circulating immune complexes in the majority of the cases and to autoantibodies in some. The increased collagen binding activity was associated in postpubertal patients with the presence of diabetic microangiopathy, suggesting a pathogenetic role.     

Cytostatic and antiherpesvirus type 1 and 2 activities of 1-beta-D-arabinofuranosylthymine (ara T) prodrugs

A series of derivatives of the antibiotic 1-beta-D-arabinofuranosylthymine (ara T) was synthesized by esterification of the hydroxy group in the 5'-position of the arabinose moiety of the nucleoside with straight-chain and branched-chain carboxylic acids: acetyl-ara T, butyryl-ara T, valeroyl-ara T, pivaloyl-ara T and palmitoyl-ara T. These ara T prodrugs were evaluated for their effect on growth of L5178y mouse lymphoma cells and noninfected BHK-21 cells as well as for their antiviral activity in Herpes simplex virus type 1 and 2 infected BHK-21 cells. All compounds exhibited a marked antiherpes virus activity, whereas the cytostatic activity of two of them, the pivaleric ester and the palmitic ester, was extremely weak. The relative antiviral indices of the 5'-pivaloyl-ara T and 5'-palmitoyl-ara T were found to be much better than the index of ara T itself.     

Platelet-derived growth factor (PDGF) in type 1 diabetes mellitus

In 10 patients with type 1 diabetes mellitus, platelet-derived growth factor (PDGF) was assessed using an in vitro assay based on the stimulation of DNA synthesis in the 3T3 mouse fibroblast cell line. beta-Thromboglobulin (beta-TG) was used as an index for platelet alpha-granules content. Platelet beta-TG content and PDGF were markedly decreased in diabetic patients while plasma beta-TG was increased as compared with control subjects. In diabetic patients, a significant negative correlation was found between plasma beta-TG level and beta-TG total platelet content, associated with a significant positive correlation between platelet beta-TG content and PDGF. These results suggest that PDGF release might be increased in diabetic subjects. This may account in part for the cell proliferation observed in diabetic angiopathy.     

Interpersonal predictors of HbA(1c) in patients with type 1 diabetes

OBJECTIVE: Research suggests that increased collaboration and satisfaction in the patient-provider relationship is associated with better outcomes in patients with diabetes. In adults, an interpersonal style characterized by low trust of others and excessive self-reliance is known as "dismissing attachment style." We hypothesized that diabetic patients with dismissing attachment style, due to a decreased ability to collaborate with providers and others, would have significantly higher HbA(1c) levels than patients with secure attachment style. RESEARCH DESIGN AND METHODS: From 276 adult tertiary care patients with type 1 diabetes, we obtained mean HbA(1c) levels over the prior year and assessed patient attachment style, demographics, and clinical characteristics. We used chi(2) tests and logistic regression to determine whether attachment style was associated with HbA(1c) levels. RESULTS: We found that 62% of patients with dismissing attachment style had mean HbA(1c) levels >or=8% compared with 34% of patients with secure attachment style (P = 0.002). After adjusting for demographics, diabetes severity, medical comorbidity, and depression, dismissing attachment style remained significantly associated with HbA(1c) levels >or=8%, compared with secure attachment style (odds ratio 2.5, 95% CI 1.1-6.0). CONCLUSIONS: We have found that dismissing attachment style is associated with a higher risk for poor glycemic control. This has relevance from a population-based perspective because approximately 25% of the general population has a dismissing attachment style. Attachment style is easily measured using self-report instruments and may inform clinicians how to work with patients who are less engaged in the health care relationship.     

Improved method for molecular diagnosis of myotonic dystrophy type 1 (DM1)

Myotonic dystrophy type 1 (DM1) has been identified as the amplification of a polymorphic (CTG)n repeat in the 3' untranslated region of a gene encoding a serine/threonine kinase (DMPK). The length of the CTG repeat correlates with clinical severity and the age at onset of the disease. Thus, the ability to perform quick and accurate molecular genetic diagnoses is of great importance to patients and their families. Polymerase chain reaction (PCR) and Southern blots are essential methods for such diagnoses. All previously published methods are based on Southern blots using radioactive probes. Furthermore, the enzymes used for DNA digestion result in larger fragments, which makes it difficult to accurately determine the insert sizes. In this study, we report an improved method for molecular diagnosis of DM1. This method employs an initial screening with PCR followed by Southern blots using nonradioactive probes and TaqI as the enzyme, and provides a much better resolution of the labeled bands.     

Adult-onset atypical (type 1) diabetes: additional insights and differences with type 1A diabetes in a European Mediterranean population

OBJECTIVE: In 1997, the American Diabetes Association proposed two subcategories for type 1 diabetes: type 1A or immunomediated diabetes and type 1B or idiopathic diabetes characterized by negative beta-cell autoimmunity markers, lack of association with HLA, and fluctuating insulinopenia. The aim of this study was to examine clinical characteristics, beta-cell function, HLA typing, and mutations in maturity-onset diabetes of the young (MODY) genes in patients with atypical type 1 diabetes (type 1 diabetes diagnosed at onset, without pancreatic autoantibodies and fluctuating insulinopenia). RESEARCH DESIGN AND METHODS: Eight patients with atypical type 1 diabetes (all men, 30.7 +/- 7.6 years) and 16 newly diagnosed age- and sex-matched patients with type 1A diabetes were studied retrospectively. Islet cell, GAD, tyrosine phosphatase and insulin antibodies, and basal and stimulated plasma C-peptide were measured at onset and after 1 year. HLA-DRB1-DQA1-DQB1 typing and screening for mutations in the HNF-1alpha and HNF-4alpha genes were performed from genomic DNA. RESULTS: Atypical patients displayed significantly higher BMI and better beta-cell function at onset and after 12 months. Three patients carried protective or neutral type 1 diabetes haplotypes, five patients displayed heterozygosity for susceptible and protective haplotypes, and seven patients showed Asp(beta57). We found a nondescribed variant Pro436Ser in exon 10 of the HNF-4alpha gene in one atypical patient without susceptible haplotypes. CONCLUSIONS: In our population, there are atypical forms of young adult-onset ketosis-prone diabetes initially diagnosed as type 1 diabetes, differing from type 1 diabetes in the absence of beta-cell autoimmunity, persistent beta-cell function capacity, fluctuating insulin requirements and ketosis-prone episodes, as well as clinical features of type 2 diabetes. Only one subgroup could be strictly classified as having type 1B diabetes. Additional information is still needed to improve our understanding of the mechanisms that finally lead to the disease.     

Molecular and biological characterization of a herpes simplex virus type 1 (HSV-1) neuroinvasiveness gene

Pathogenetic studies of herpes simplex virus type 1 (HSV-1) strains ANG and its mouse brain-passaged descendant ANG path revealed no difference in neurovirulence but a significant difference in neuroinvasiveness. Thus, both viruses induced a fatal encephalitis in mice after direct injection into the brain, but only ANG path induced lethal neurologic disease after inoculation on rear footpads. The difference in neuroinvasiveness is not related to the capacity to replicate in mouse neural tissues or mouse cells in general, but is specifically related to virus entry into the peripheral nervous system in the footpad. Marker rescue experiments in which ANG path genes were used to confer neuroinvasiveness on ANG indicated that the gene that codes for glycoprotein D (gD) is responsible for the phenotypic difference. Analyses of the gD genes by dideoxy-sequencing techniques identified a base difference in the coding sequences and predicted that the ANG gD gene codes for alanine (GCC codon) at amino acid position 84 in the open reading frame and the ANG path gD gene codes for glycine (GGC codon) at this site. Using these data, an oligonucleotide probe predicted to be specific for the ANG path gD gene was prepared, and in Southern blot analyses, this probe revealed that neuroinvasiveness-rescued agents had incorporated the base change seen in the ANG path gD gene. We conclude that HSV-1 glycoprotein D functions to effect neuroinvasiveness and we discuss potential mechanisms that may be involved.     

Patient satisfaction and glycemic control after 1 year with inhaled insulin (Exubera) in patients with type 1 or type 2 diabetes

OBJECTIVE: The aim of this study was to determine patient satisfaction in patients with type 1 or type 2 diabetes receiving an inhaled insulin or subcutaneous insulin regimen, as assessed by pooled analysis of two 12-week parent studies and 1-year extension studies. RESEARCH DESIGN AND METHODS: In the 12-week parent studies, patients with type 1 (n = 70) or type 2 (n = 51) diabetes were randomized to an inhaled insulin or subcutaneous insulin regimen. In the 1-year extension studies, patients were allowed to select either treatment regimen. Patient satisfaction was assessed at baseline, week 12, and 1 year using the Patient Satisfaction with Insulin Therapy questionnaire. RESULTS: Of the 60 patients who received inhaled insulin during the parent studies, 85.0% (n = 51) chose to continue treatment, 13.3% (n = 8) switched to subcutaneous insulin, and 1.7% (n = 1) did not continue. Of the 61 patients who received subcutaneous insulin, 21.3% (n = 13) chose to continue treatment, 75.4% (n = 46) switched to inhaled insulin, and 3.3% (n = 2) did not continue. From baseline (parent studies) to 1 year (extension studies), HbA(1c) reductions of 0.8% were sustained, and greater improvements were observed in the inhaled insulin group compared with the subcutaneous insulin group in terms of overall satisfaction (37.9 vs. 3.1%; P < 0.01) and ease of use (43.2 vs. -0.9%; P < 0.01). CONCLUSIONS: Inhaled insulin was preferred over subcutaneous insulin, which resulted in greater patient satisfaction up to 1 year in patients with type 1 or type 2 diabetes with durable effects on HbA(1c) levels.     

Interleukin-1 (IL-1) family of cytokines: role in type 2 diabetes

Cytokines are small cell signaling protein molecules which encompass a large and diverse family. They consist of immunomodulating agents such as interleukins and inteferons. Virtually all nucleated cells, especially endo/epithelial cells and macrophages are potent producers of IL-1, IL-6 and TNF-α. IL-1 family is a group of cytokines which play a central role in the regulation of immune and inflammatory responses. Type 2 diabetes (T2D) has been recognized as an immune mediated disease leading to impaired insulin signaling and selective destruction of insulin producing β-cells in which cytokines play an important role. Disturbance of anti-inflammatory response could be a critical component of the chronic inflammation resulting in T2D. IL-1 family of cytokines has important roles in endocrinology and in the regulation of responses associated with inflammatory stress. The IL-1 family consists of two pro-inflammatory cytokines, IL-1α and IL-1β, and a naturally occurring anti-inflammatory agent, the IL-1 receptor antagonist (IL-1Ra or IL-1RN). This review is an insight into the different types of cytokines belonging to IL-1 family, their modes of action and association with Type 2 diabetes.