Bart Van der Auwera

Screening for Insulitis in Adult Autoantibody-Positive Organ Donors

Antibodies against islet cell antigens are used as predictive markers of type 1 diabetes, but it is unknown whether they reflect an ongoing autoimmune process in islet tissue. We investigated whether organs from adult donors that are positive for autoantibodies (aAbs) against islet cell antigens exhibit insulitis and/or a reduced β-cell mass. Serum from 1,507 organ donors (age 25–60 years) was analyzed for islet cell antibodies (ICAs), glutamate decarboxylase aAbs (GADAs), insulinoma-associated protein 2 aAbs (IA-2As), and insulin aAbs. Tissue from the 62 aAb+ donors (4.1%) and from matched controls was examined for the presence of insulitis and for the relative area of insulin+ cells. Insulitis was detected in two cases; it was found in 3 and 9% of the islets and consisted of CD3+/CD8+ T-cells and CD68+ macrophages; in one case, it was associated with insulin+ cells that expressed the proliferation marker Ki67. Both subjects belonged to the subgroup of three donors with positivity for ICA, GADA, and IA-2-Ab and for the susceptible HLA-DQ genotype. Comparison of relative β-cell area in aAb+ and aAb− donors did not show a significant difference. Insulitis was found in two of the three cases that presented at least three aAbs but in none of the other 59 antibody+ subjects or 62 matched controls. It was only detected in <10% of the islets, some of which presented signs of β-cell proliferation. No decrease in β-cell mass was detected in cases with insulitis or in the group of antibody+ subjects.

DRB1*0403 Protects Against IDDM in Caucasians With the High-Risk Heterozygous DQA1*0301-DQB1*0302/DQA1*0501-DQB1*0201 Genotype

The human leukocyte antigen (HLA) class II genotype DQA1*0301-DQB1*0302/DQA1*0501-DQB1*0201 has been identified as a marker strongly predisposing to insulin-dependent diabetes mellitus (IDDM) in Caucasian populations. Its frequency in control populations (1–3%) is still, however, 1 order of magnitude higher than the prevalence of IDDM, suggesting that its penetrance can be modified by protective factors. In this study we searched for such a factor in the DRB1 locus by studying DRB1*04 polymorphism in 174 European Caucasian IDDM patients and 73 nondiabetic control subjects, all sharing the HLA-DR3/DR4 phenotype. Significant protection was encoded by the DRB1*0403 allele, which was observed in 5 of 49 control subjects (10%) and none of 171 IDDM patients (0%) with the DQA1*0301-DQB1*0302/DQA1*0501-DQB1*0201 genotype (RR = 0.02 [0.01–0.18], P < 0.0005). These data support the concept that protective HLA class II genes can overrule the risk caused by HLA-DQ susceptibility dimers. They also contribute to a possible strategy to screen for nondiabetic individuals with increased genetic risk of developing IDDM.

Relative and absolute HLA-DQA1-DQB1 linked risk for developing type I diabetes before 40 years of age in the Belgian population: implications for future prevention studies

HLA-DQ genotyping remains the cornerstone of genetic risk stratification in type I diabetes prediction and prevention studies. We developed a genetic screening strategy for predisposition to type I diabetes in the Belgian population based upon HLA-DQA1-DQB1 typing and taking into account the age at clinical onset. A group of 1866 autoantibody-positive type I patients below age 40 years recruited by the Belgian Diabetes Registry and a group of 750 control subjects were DQA1-DQB1 genotyped. In the total study population 16 different DQA1-DQB1 haplotypes were revealed, allowing the stratification of 81 genotypes in ten different genotype groups. Apart from the highest risk DQA1*-DQB1* genotype 0301-0302/0501-0201 (odds ratio 21; absolute risk 6%), three other genotype groups conferred a highly significant disease risk (p < 10(-6)). Altogether, these susceptibility genotypes were carried by 9% of the control subjects versus 60% of the patients diagnosed before age 40 years and up to 70% of those under age 5 years. All other genotypes were protective, neutral, infrequent or associated with a moderate protection or susceptibility. A strong, although not absolute protection was conferred by DQB1*0602-positive haplotypes (odds ratio = 0.03). This study in a large cohort of autoantibody-positive patients shows that a DQA1-DQB1-based genotyping strategy allows the identification of a subgroup representing less than 10% of the Belgian population but harbouring the majority of future type I patients arising in childhood or early adulthood. Future prediction and prevention studies should take into account the age dependency of this HLA-DQ associated risk.

IFIH1 gene polymorphisms in type 1 diabetes: Genetic association analysis and genotype–phenotype correlation in the Belgian population

The evaluation of susceptibility loci in a registry-based setting could be an important addition to the current predictive and screening models in T1D. Therefore, the aim of this study was to evaluate the importance of one of these loci, IFIH1. T1D patients (n=1981), control subjects (n=2092) and 430 families were genotyped for HLA-DQ and IFIH1 nsSNP rs1990760 (Ala946Thr). In the association analysis, the allelic frequencies, A (62.4% vs. 61.3%) and G (37.6% vs. 38.7%) were similar in cases and controls (chi(2) = 0.98, p = 0.32), the genotypic frequencies reveals a weak association with T1D (chi(2) = 6.79, p = 0.03), no significant transmission distortions in families (%T; A = 51.4%, G = 48.0 %, chi(2) = 1.76, p = 0.19) and no interaction with HLA-DQ-linked risk. Furthermore, no genotype-phenotype correlation was observed. In conclusion, IFIH1 has no important role in T1D risk assessment in a registry-based Belgian population.

HLA-A*24 Is an Independent Predictor of 5-Year Progression to Diabetes in Autoantibody-Positive First-Degree Relatives of Type 1 Diabetic Patients

We investigated whether HLA-A*24 typing complements screening for HLA-DQ and for antibodies (Abs) against insulin, GAD, IA-2 (IA-2A), and zinc transporter-8 (ZnT8A) for prediction of rapid progression to type 1 diabetes (T1D). Persistently Ab+ siblings/offspring (n = 288; aged 0–39 years) of T1D patients were genotyped for HLA-DQA1-DQB1 and HLA-A*24 and monitored for development of diabetes within 5 years of first Ab+. HLA-A*24 (P = 0.009), HLA-DQ2/DQ8 (P = 0.001), and positivity for IA-2A ± ZnT8A (P < 0.001) were associated with development of T1D in multivariate analysis. The 5-year risk increased with the number of the above three markers present (n = 0: 6%; n = 1: 18%; n = 2: 46%; n = 3: 100%). Positivity for one or more markers identified a subgroup of 171 (59%) containing 88% of rapid progressors. The combined presence of HLA-A*24 and IA-2A+ ± ZnT8A+ defined a subgroup of 18 (6%) with an 82% diabetes risk. Among IA-2A+ ± ZnT8A+ relatives, identification of HLA-A*24 carriers in addition to HLA-DQ2/DQ8 carriers increased screening sensitivity for relatives at high Ab- and HLA-inferred risk (64% progression; P = 0.002). In conclusion, HLA-A*24 independently predicts rapid progression to T1D in Ab+ relatives and complements IA-2A, ZnT8A, and HLA-DQ2/DQ8 for identifying participants in immunointervention trials.

Increased Prevalence of Abnormal Immunoglobulin M, G, and A Concentrations at Clinical Onset of Insulin-Dependent Diabetes Mellitus : A Registry-Based Study

In view of the reported association of insulin-dependent diabetes mellitus (IDDM) with viral infections, (non-) islet-specific immune changes, and partial immunodeficiencies, we used immunonephelometry to measure circulating levels of IgM, IgG, and IgA in a registry-based group of IDDM patients under age 40 years at clinical onset (n = 397) and in age-matched nondiabetic siblings (n = 316) and control subjects (n = 322). Overall, IgM and IgA concentrations were higher, and IgG concentrations lower, in patients than in control subjects or siblings (P < 0.001). In siblings, IgM concentrations were higher than in control subjects (P < 0.001). Using age-adjusted reference intervals, abnormal Ig concentrations were noted in 27% of the patients at onset versus only 10% of the siblings and 7% of the control subjects (P < 0.001). For onset between 20 and 40 years (n = 220), 30% of the patients presented either increased IgM levels (21%) or decreased IgG levels (11%). Both independent phenomena occurred regardless of diabetes-associated immune and genetic markers. In patients and siblings, IgM levels were positively correlated with pancreatic lipase activity. In diabetic children (0-9 years; n = 65), a subgroup presented increased IgA levels (15%) in association with the highest HLA DQ-linked genetic risk and elevated IgM levels. The changes in total Ig concentrations at onset were largely reversed under insulin therapy. They may reflect exposure to environmental triggers, such as viral infections, or to (relative) insulinopenia prior to clinical disease onset. Whatever their cause, different serum Ig levels exist in different age groups of recent-onset IDDM patients.

Graves Hyperthyroidism After Stopping Immunosuppressive Therapy in Type 1 Diabetic Islet Cell Recipients With Pretransplant TPO Autoantibodies

OBJECTIVE After an initially successful islet cell transplantation, a number of patients return to C-peptide negativity, and therefore immunosuppressive therapy is discontinued. Some are then found to have developed Graves disease. We examined the risk of Graves disease after immunosuppression. RESEARCH DESIGN AND METHODS Immunosuppressive therapy was stopped in 13 type 1 diabetic islet cell recipients who had received one course of antithymocyte globulin and maintenance doses of mycophenolate mofetil and a calcineurin inhibitor. None had a history of thyroid disease. RESULTS In four patients, clinical Graves hyperthyroidism was observed within 21 months after discontinuation and 30–71 months after the start of immunosuppressive therapy. All four patients exhibited a pretransplant positivity for thyroid peroxidase (TPO) autoantibodies, while the nine others were TPO negative pre- and posttransplantation. CONCLUSIONS Type 1 diabetic recipients of islet cell grafts with pretransplant TPO autoantibody positivity exhibit a high risk for developing Graves hyperthyroidism after immunosuppressive therapy is discontinued for a failing graft.

Association of IL-2RA/CD25 with type 1 diabetes in the Belgian population

Our goals were to study the proposed association of IL-2RA /CD25 with type 1 diabetes in the Belgian population over a broad age range, and to explore possible correlations with disease phenotypes, immune markers, HLA-DQ, INS, and PTPN22. Patients (n = 1954), healthy controls (n = 2082), and families (n = 420) were genotyped for IL-2RA/CD25 rs41295061(C>A), HLA-DQ, INS-VNTR and PTPN22. IL-2RA/CD25 was associated with type 1 diabetes (χ(2) = 26.8, p < 0.001 for alleles and χ(2) = 29.6, p < 0.001 for genotypes). The C allele (odds ratios [OR] = 1.59) and C/C genotype (OR = 1.56) were identified as susceptibility variants, whereas the A allele (OR = 0.63), A/A genotype (OR = 0.14), and A/C genotype (OR = 0.69) as protective variants. IL-2RA/CD25 is associated with both early-onset and late-onset type 1 diabetes, but with a larger effect size in early-onset disease. There was a nonsignificant tendency toward transmission distortion (p = 0.063). Except a tendency toward younger age at onset in carriers of the C/C genotype, no correlations with disease phenotype, immune markers, HLA-DQ, INS and PTPN22 were observed. Also, the frequency of the susceptible genotype was higher in early-onset compared with late-onset TID patients (p = 0.015). In conclusion, IL-2RA/CD25 is associated with type 1 diabetes in the Belgian population, independently of disease phenotype and other biologic markers.

Clinical and biological characteristics of diabetic patients under age 40 in Cameroon: relation to autoantibody status and comparison with Belgian patients.

AIMS We investigated the prevalence of diabetes autoantibodies (Abs) in Cameroonian patients and controls, assessed their contribution in disease classification and compared results with data from Belgium. METHODS Abs against GAD (GADA), IA-2 (IA-2A) and zinc transporter 8 (ZnT8A) were assessed in 302 recently diagnosed Cameroonian patients with diabetes and 184 control subjects without diabetes aged below 40 years. RESULTS Only 27 (9%) Cameroonian patients were younger than 15 years. Overall, 29% of patients presented at least one diabetes-associated antibody vs 9% in healthy controls (24% vs 7% for GADA (p<0.001), 10% vs 3% for IA-2A (p<0.006), 4% vs 2% for ZnT8A). Ab(+) patients had lower C-peptide levels (p<0.001), were more often insulin-treated (p<0.002) and were as frequently diagnosed with type 1 diabetes as Ab(-) patients. Only 43% of Ab(+) patients aged 15-39 years were clinically classified as having type 1 diabetes in Cameroon vs 96% in Belgium (p<0.001). Not one Ab(+) Cameroonian patient carried HLA-DQ2/DQ8 genotype vs 23% of Belgian Ab(+) patients (p<0.001). Younger age at diagnosis and antibody positivity were independent predictors of insulin therapy. Ab(+) Cameroonian patients were older (p<0.001), had higher BMI (p<0.001) and lower Ab titers than Belgian Ab(+) patients. In ketonuric patients, prevalence of autoantibodies was similar as in non-ketonuric patients. CONCLUSIONS In Cameroonian patients with diabetes aged under 40 years, antibody-positivity is not clearly related to disease phenotype, but may help predict the need for insulin treatment.

HLA-A*24 Carrier Status and Autoantibody Surges Posttransplantation Associate With Poor Functional Outcome in Recipients of an Islet Allograft

OBJECTIVE We investigated whether changes in islet autoantibody profile and presence of HLA risk markers, reported to predict rapid β-cell loss in pre–type 1 diabetes, associate with poor functional outcome in islet allograft recipients. RESEARCH DESIGN AND METHODS Forty-one patients received ≥2.3 million β-cells/kg body wt in one to two intraportal implantations. Outcome after 6–18 months was assessed by C-peptide (random and stimulated), insulin dose, and HbA1c. RESULTS Patients carrying HLA-A*24-positive or experiencing a significant autoantibody surge within 6 months after the first transplantation (n = 19) had lower C-peptide levels (P ≤ 0.003) and higher insulin needs (P < 0.001) despite higher HbA1c levels (P ≤ 0.018). They became less often insulin independent (16% vs. 68%, P = 0.002) and remained less often C-peptide positive (47% vs. 100%, P < 0.001) than recipients lacking both risk factors. HLA-A*24 positivity or an autoantibody surge predicted insulin dependence (P = 0.007). CONCLUSIONS HLA-A*24 and early autoantibody surge after islet implantation associate with poor functional graft outcome.