Autoantibodies to the 65-kDa isoform of glutamate decarboxylase GAD65 (GAD65Ab) are strong candidates for a pathological role in Stiff-Person syndrome (SPS). We have analyzed the binding specificity ...of the GAD65Ab in serum and cerebrospinal fluid (CSF) of 12 patients with SPS by competitive displacement studies with GAD65-specific rFab-derived from a number of human and mouse mAbs specific for different determinants on the Ag. We demonstrate considerable differences in the epitope specificity when comparing paired serum and CSF samples, suggesting local stimulation of B cells in the CSF compartment of these patients. Moreover, these autoantibodies strongly inhibit the enzymatic activity of GAD65, thus blocking the formation of the neurotransmitter gamma-aminobutyric acid. The capacity of the sera to inhibit the enzymatic activity of GAD65 correlated with their binding to a conformational C-terminal Ab epitope. Investigation of the inhibitory mechanism revealed that the inhibition could not be overcome by high concentrations of glutamate or the cofactor pyridoxal phosphate, suggesting a noncompetitive inhibitory mechanism. Finally, we identified a linear epitope on amino acids residues 4-22 of GAD65 that was recognized solely by autoantibodies from patients with SPS but not by serum from type 1 diabetes patients. A mAb (N-GAD65 mAb) recognizing this N-terminal epitope was successfully humanized to enhance its potential therapeutic value by reducing its overall immunogenicity.
This study aimed to test whether injections of alum-formulated glutamic acid decarboxylase 65 (GAD), a major autoantigen in type 1 diabetes mellitus, would reverse recent-onset disease. C-peptide ...levels declined in both the treatment group and the control group, without significant between-group differences at month 15 (the primary end point), but they had declined significantly more slowly with treatment by month 30. The authors conclude that alum-formulated GAD may help preserve residual insulin secretion in patients with recent-onset type 1 diabetes.
Study patients received injections of alum-formulated glutamic acid decarboxylase 65 (GAD). C-peptide levels declined in both the treatment group and the control group, but they had declined significantly more slowly with treatment by month 30.
Type 1 diabetes mellitus is an autoimmune disease
1
that causes substantial morbidity and mortality.
2
,
3
Even modest residual insulin secretion, with stimulated C-peptide levels above 0.2 nmol per liter (0.6 ng per milliliter), has been reported to provide clinically meaningful benefits in terms of reducing long-term complications.
4
However, most attempts to preserve residual beta-cell function have achieved minimal benefits or have been associated with adverse effects.
5
–
14
Treatment with anti-CD3 monoclonal antibodies appears promising, although many patients in whom this approach has been used have had therapy-related adverse events.
15
,
16
As an alternative to immunosuppression, autoantigens may be used to . . .
Identifying maturity-onset diabetes of the young (MODY) in pediatric populations close to diabetes diagnosis is difficult. Misdiagnosis and unnecessary insulin treatment are common. We aimed to ...identify the discriminatory clinical features at diabetes diagnosis of patients with glucokinase (GCK), hepatocyte nuclear factor-1A (HNF1A), and HNF4A MODY in the pediatric population.
Swedish patients (
= 3,933) aged 1-18 years, diagnosed with diabetes May 2005 to December 2010, were recruited from the national consecutive prospective cohort Better Diabetes Diagnosis. Clinical data, islet autoantibodies (GAD insulinoma antigen-2, zinc transporter 8, and insulin autoantibodies), HLA type, and C-peptide were collected at diagnosis. MODY was identified by sequencing
,
, and
, through either routine clinical or research testing.
The minimal prevalence of MODY was 1.2%. Discriminatory factors for MODY at diagnosis included four islet autoantibody negativity (100% vs. 11% not-known MODY;
= 2 × 10
), HbA
(7.0% vs. 10.7% 53 vs. 93 mmol/mol;
= 1 × 10
), plasma glucose (11.7 vs. 26.7 mmol/L;
= 3 × 10
), parental diabetes (63% vs. 12%;
= 1 × 10
), and diabetic ketoacidosis (0% vs. 15%;
= 0.001). Testing 303 autoantibody-negative patients identified 46 patients with MODY (detection rate 15%). Limiting testing to the 73 islet autoantibody-negative patients with HbA
<7.5% (58 mmol/mol) at diagnosis identified 36 out of 46 (78%) patients with MODY (detection rate 49%). On follow-up, the 46 patients with MODY had excellent glycemic control, with an HbA
of 6.4% (47 mmol/mol), with 42 out of 46 (91%) patients not on insulin treatment.
At diagnosis of pediatric diabetes, absence of all islet autoantibodies and modest hyperglycemia (HbA
<7.5% 58 mmol/mol) should result in testing for GCK, HNF1A, and HNF4A MODY. Testing all 12% patients negative for four islet autoantibodies is an effective strategy for not missing MODY but will result in a lower detection rate. Identifying MODY results in excellent long-term glycemic control without insulin.
Abstract
Context:
Screening of autoimmune thyroid disease in children with type 1 diabetes is important but varies between clinics.
Objective:
To determine the predictive value of thyroid ...autoantibodies, thyroid function, islet autoantibodies, and HLA-DQ at diagnosis of type 1 diabetes for autoimmune thyroid disease during follow-up.
Setting:
Forty-three Swedish pediatric endocrinology units.
Design, Patients, and Main Outcome Measures:
At diagnosis of type 1 diabetes, autoantibodies against thyroid peroxidase (TPOAb), thyroglobulin (TGAb), glutamic acid decarboxylase (GADA), insulin, insulinoma-associated protein-2, and 3 variants of zinc transporter 8 (ZnT8W/R/QA) HLA-DQA1-B1 genotypes and thyroid function were analyzed in 2433 children. After 5.1 to 9.5 years, information on thyroxine treatment was gathered from the Swedish National Board of Health and Welfare’s Prescribed Drug Register.
Results:
Thyroxine was prescribed to 6% of patients. In patients <5 years of age, female sex hazard ratio (HR) = 4.60; P = 0.008 and GADA (HR = 5.80; P = 0.02) were predictors. In patients 5 to 10 years old, TPOAb (HR = 20.56; P < 0.0001), TGAb (HR = 3.40; P = 0.006), and thyroid-stimulating hormone (TSH) (HR = 3.64; P < 0.001) were predictors, whereas in 10 to 15 year olds, TPOAb (HR = 17.00; P < 0.001) and TSH (HR = 4.11; P < 0.001) predicted thyroxine prescription.
Conclusion:
In addition to TPOAb and TSH, GADA at diagnosis of type 1 diabetes is important for the prediction of autoimmune thyroid disease in children <5 years of age.
We studied whether markers at type 1 diabetes diagnosis were predictive of later autoimmune thyroid disease. We found that TPOAb and TSH as well as GADA were predictive in girls ˂5 years old at diagnosis.
Objective
To investigate long‐term effects on glycaemic control, ketoacidosis, serious hypoglycaemic events, insulin requirements, and body mass index standard deviation scores (BMI‐SDS) in children ...and adolescents with type 1 diabetes starting on continuous subcutaneous insulin infusion (CSII) compared with children and adolescents treated with multiple daily injections (MDI).
Methods
This retrospective case–control study compares 216 patients starting CSII with a control group on MDI (n = 215), matched for glycated hemoglobin (HbA1c), sex, and age during a 2‐yr period. Variables collected were gender, age, HbA1c, insulin requirement, BMI, BMI‐SDS, ketoacidosis, and serious hypoglycaemic events.
Results
In the CSII group there was an improvement in HbA1c after 6 and 12 months compared with the MDI group. For boys and girls separately the same effect was detected after 6 months, but only for boys after 12 months. The incidence of ketoacidosis was higher in the CSII group compared with the MDI group (2.8 vs. 0.5/100 person‐yr). The incidences of severe hypoglycaemic episodes per 100 person‐yr were three in the CSII group and six in the MDI group (p < 0.05). After 6, 12, and 24 months, the insulin requirement was higher in the MDI group.
Conclusions
This study shows that treatment with CSII resulted in an improvement in HbA1c levels up to 1 yr and decreased the number of severe hypoglycaemic events, but the frequency of ketoacidosis increased. The major challenge is to identify methods to maintain the HbA1c improvement, especially among older children and teenagers, and reduce the frequency of ketoacidosis.
Recombinant Fabs of Human Monoclonal Antibodies Specific to the Middle Epitope of GAD65 Inhibit Type 1 Diabetes–Specific GAD65Abs
Carolyn J. Padoa 1 2 ,
J. Paul Banga 3 ,
Anne-Marie Madec 4 ,
Manfred ...Ziegler 5 ,
Michael Schlosser 6 ,
Eva Ortqvist 7 ,
Ingrid Kockum 8 ,
Jerry Palmer 1 ,
Olov Rolandsson 9 ,
Katherine A. Binder 1 ,
Jefferson Foote 10 ,
Dong Luo 1 and
Christiane S. Hampe 1
1 Department of Medicine, University of Washington, Seattle, Washington
2 Department of Chemical Pathology, University of the Witwatersrand & National Health Laboratory Services, Johannesburg, South
Africa
3 Division of Medicine, Guy’s, Kings and St. Thomas’ School of Medicine, London, U.K
4 Institut National de la Santé et de la Recherche Médicale, Laennec Faculty of Medicine, University of Lyon, Lyon, France
5 Institute of Diabetes “Gerhardt Katsch,” Karlsburg, Germany
6 Institute of Pathophysiology, Ernst Moritz Arndt University of Greifswald, Karlsburg, Germany
7 Department of Woman and Child Health, Karolinska Institutet, Stockholm, Sweden
8 Department of Molecular Medicine, Clinical Genetics, Karolinska Institutet, Stockholm, Sweden
9 Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden
10 Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, Washington
Address correspondence and reprint requests to Dr. Christiane S. Hampe, Department of Medicine, Box 357710, University of
Washington, Seattle, WA 98195. E-mail: champe{at}u.washington.edu
Abstract
Autoantibodies to the 65-kDa isoform of GAD (GAD65Abs) are associated with type 1 diabetes development, but the conformational
nature of the GAD65Ab epitopes complicates the evaluation of disease risk. Six GAD65-specific recombinant Fabs (rFabs) were
cloned from monoclonal antibodies b96.11, DP-C, DP-A, DPD, 144, and 221–442. The binding of GAD65Abs in 61 type 1 diabetic
patients to GAD65 was analyzed by competitive radioimmunoassays with the six rFabs to ascertain disease-specific GAD65Ab binding
specificities. The median binding was reduced significantly by rFab b96.11 (72%) ( P < 0.0001), DP-A (84%) ( P < 0.0001), DP-C (84%) ( P < 0.0001), 221–442 (79%) ( P < 0.0001), and DP-D (80%) ( P < 0.0001). The competition pattern in type 1 diabetic patients differed from that in GAD65Ab-positive late autoimmune diabetes
in adults (LADA) patients ( n = 44), first-degree relatives ( n = 38), and healthy individuals ( n = 14). Whereas 87 and 72% of the type 1 diabetic sera were competed by rFab b96.11 and DP-C, respectively, only 34 and 26%
of LADA patients, 18 and 25% of first-degree relatives, and 7 and 28% of healthy individuals showed competition ( P < 0.0001). These findings support the view that type 1 diabetes is associated with disease- and epitope-specific GAD65Abs
and supports the notion that the middle epitope is disease associated. These GAD65-specific rFabs should prove useful in predicting
type 1 diabetes and in the study of conformational GAD65Ab epitopes.
APS-1, autoimmune polyendocrine syndrome type 1
CDR, complementarity-determining region
GAD65Ab, autoantibody to the 65-kDa isoform of GAD
LADA, late autoimmune diabetes in adults
mAb, monoclonal antibody
rFab, recombinant Fab
RIA, radioimmunoassay
Footnotes
Accepted July 22, 2003.
Received May 8, 2003.
DIABETES
Selective immunoglobulin A deficiency (IgAD) is the most common primary immunodeficiency in Caucasians. It has previously been suggested to be associated with a variety of concomitant autoimmune ...diseases. In this review, we present data on the prevalence of IgAD in patients with Graves disease (GD), systemic lupus erythematosus (SLE), type 1 diabetes (T1D), celiac disease (CD), myasthenia gravis (MG) and rheumatoid arthritis (RA) on the basis of both our own recent large-scale screening results and literature data. Genetic factors are important for the development of both IgAD and various autoimmune disorders, including GD, SLE, T1D, CD, MG and RA, and a strong association with the major histocompatibility complex (MHC) region has been reported. In addition, non-MHC genes, such as interferon-induced helicase 1 (IFIH1) and c-type lectin domain family 16, member A (CLEC16A), are also associated with the development of IgAD and some of the above diseases. This indicates a possible common genetic background. In this review, we present suggestive evidence for a shared genetic predisposition between these disorders.
Objective
To evaluate longitudinal serum insulin‐like growth factor‐I (IGF‐I) in a large cohort of children and adolescents with type 1 diabetes in relation to hemoglobin A1c (HbA1c), age, diabetes ...duration, and body mass index (BMI), its association to height and retinopathy, and in comparison with healthy subject references.
Methods
A total of 2683 serum IGF‐I values were obtained from 806 children and adolescents with T1DM, from annual blood samples for up to 6 consecutive years.
Results
In a multiple regression analysis IGF‐I values were negatively correlated to HbA1c and diabetes duration, and positively correlated to BMI (P < .001, P < .001, and P < .001, respectively, adjusted r2 = 0.102). Children and adolescents with T1DM had lower mean IGF‐I levels and reference interval limits compared to healthy subjects. In boys, mean (SD) IGF‐I SD score (SDS) levels were −1.04 (±1.3) calculated from the healthy reference. IGF‐I peaked at 15 years of age, similarly to healthy controls, but with markedly lower levels in late puberty. Girls were more affected at later stages of puberty but with a slightly less depressed overall mean IGF‐I SDS of −0.69 (±1.2). In a subgroup of 746 subjects with fundus photography, a negative correlation was seen between individual mean IGF‐I SDS and preproliferative retinopathy (P = .004, adjusted r2 = 0.021). In another subgroup of 84 adolescents, no correlation was seen between individual mean IGF‐I SDS and target height SDS or distance to target height SDS.
Conclusion
Poor metabolic control and diabetes duration impact negatively on serum IGF‐I levels. A low individual mean IGF‐I level was associated with progression of retinopathy independently of HbA1c, age, gender, and diabetes duration. Disease, sex and age related IGF‐I SDS may become clinical helpful as a supplement to HbA1c in predicting the long‐term outcome for children and adolescents with T1DM.
Abstract
Aim.
The aim was to determine the prevalence and clinical and temporal relationship of celiac disease (CD) in a population of Swedish children with type 1 diabetes mellitus (T1DM) before, ...during, and after the Swedish epidemic of CD (birth cohorts 1984-1996).
Methods.
Retrospective chart review between 1995 and 2005 was conducted of 1151 children (0-18 years old, born 1981-2004) with T1DM.
Results.
A prevalence of 9.1% (95% CI: 7.2-11.2) of CD in T1DM children was found. No significant difference in prevalence of CD was observed in different birth years, in contrast to the Swedish epidemic of CD. Sixty-two percent of children diagnosed with CD after T1DM onset had pathological levels of antibodies within the first 24 months. The presence or absence of gastrointestinal symptoms had no predictable value for biopsy-confirmed CD or not.
Conclusion.
The onset of CD in the T1DM population does not follow the pattern of the general population during the Swedish epidemic of CD. The shared genetic component in the human leukocyte antigen region in cases with comorbidity of CD and T1DM may overrule other CD-causing factors in the general population. Children with T1DM should be screened for CD at diagnosis and repeatedly at least during the first 2 years, even if asymptomatic.
We examined whether zinc transporter 8 autoantibodies (ZnT8A; arginine ZnT8-RA, tryptophan ZnT8-WA, and glutamine ZnT8-QA variants) differed between immigrant and Swedish patients due to different ...polymorphisms of SLC30A8, HLA-DQ, or both. Newly diagnosed autoimmune (≥1 islet autoantibody) type 1 diabetic patients (n = 2,964, <18 years, 55% male) were ascertained in the Better Diabetes Diagnosis study. Two subgroups were identified: Swedes (n = 2,160, 73%) and immigrants (non-Swedes; n = 212, 7%). Non-Swedes had less frequent ZnT8-WA (38%) than Swedes (50%), consistent with a lower frequency in the non-Swedes (37%) of SLC30A8 CT+TT (RW+WW) genotypes than in the Swedes (54%). ZnT8-RA (57 and 58%, respectively) did not differ despite a higher frequency of CC (RR) genotypes in non-Swedes (63%) than Swedes (46%). We tested whether this inconsistency was due to HLA-DQ as 2/X (2/2; 2/y; y is anything but 2 or 8), which was a major genotype in non-Swedes (40%) compared with Swedes (14%). In the non-Swedes only, 2/X (2/2; 2/y) was negatively associated with ZnT8-WA and ZnT8-QA but not ZnT8-RA. Molecular simulation showed nonbinding of the relevant ZnT8-R peptide to DQ2, explaining in part a possible lack of tolerance to ZnT8-R. At diagnosis in non-Swedes, the presence of ZnT8-RA rather than ZnT8-WA was likely due to effects of HLA-DQ2 and the SLC30A8 CC (RR) genotypes.
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