Islet autoimmunity in infants with a type 1 diabetic relative is common but is frequently restricted to one autoantibody
Colman PG, Steele C, Couper JJ, Beresford SJ, Powell T, Kewming K, Pollard A, Gellert S, Tait B, Honeyman M, Harrison LC
Diabetologia 43:203-209 (2000)
AIMS/HYPOTHESIS: To determine the sequence of development of islet autoantibodies and their relation to HLA genes in infants at risk for Type I diabetes followed from birth.
METHODS: We followed 357 (189 male, 168 female) infants, with a first degree relative with Type I diabetes for a mean of 3 years from birth. Human leukocyte antigen typing and assays for insulin autoantibodies (IAA), glutamic acid decarboxylase antibodies (GADAb) and tyrosine phosphatase IA2 (IA2Ab) antibodies were done on cord blood, and venous blood was sampled every 6 months for IAA, GADAb and IA2Ab.
RESULTS: We did not find any antibodies in 263 (73%) infants; 50 (14%) were positive for a single antibody once, 19 (5%) for a single antibody more than once and 25 (7%) for two or more antibodies. Of the latter, 10 (2.8% overall) were persistently positive; they had higher frequencies of HLA DR4 (p < 0.01) and HLA DR3, 4 (p < 0.05). Of the group persistently positive for two or more antibodies four infants developed diabetes. Insulin autoantibodies were the first ones to develop in 64% of infants with two or more antibodies.
CONCLUSION/INTERPRETATION: Infants with high risk HLA-DR alleles and multiple antibodies at high risk for diabetes were identified. A much larger group of infants had transient low level increases usually of a single antibody. Whereas transient low level positivity could be attributed to difficulties with assay technique and cut off levels for normality, the results overall support the phenomenon of transient 'self limited' islet autoimmunity in at risk infants.
Screening for preclinical type 1 diabetes in a discrete population with an apparent increased disease incidence
Colman PG, McNair P, King J, Caudwell J, Jankulovski C, PG, Tait BD, Honeyman MC, Harrison LC
Pediatric Diabetes 1:193-198 (2000)
Circulating antibodies to pancreatic beta-cell antigens are markers of islet autoimmunity. In first-degree relatives of persons with type 1 diabetes, the levels and range of antigen specificities of these islet antibodies reflect the risk for clinical diabetes. However, in the general population, in which the disease prevalence is up to 30-fold lower, the predictive value of islet antibodies is correspondingly less. Islet antibody assays are primarily research tools to identify 'prediabetic' individuals for secondary prevention trials, but can also discriminate type 1 diabetes in several clinical situations. Loss of first-phase insulin response (FPIR) to intravenous glucose signifies imminent diabetes, but FPIR is normal in most islet-antibody-positive individuals. The contribution of a single FPIR measurement to risk assessment is therefore limited, but rate of fall of FPIR may be a useful predictor. Although beta cells are destroyed by autoreactive T cells, the assay of islet antigen-reactive T cells is not routine. Genetically, the major histocompatibility complex encoding human leukocyte antigen (HLA) alleles accounts for about 50% of familial clustering of type 1 diabetes. HLA typing is not diagnostic, but can be used to differentiate high- from low-risk individuals, e.g. at birth. While 'preclinical' diagnosis raises important medical and ethical questions, an optimized screening strategy provides a basis for counselling and follow-up. Recent knowledge of disease mechanisms and 'proof-of-principle' in the non-obese diabetic (NOD) mouse model justify expectations that type 1 diabetes is preventable, and even intervention that only delays onset of clinical diabetes is likely to be cost-effective.
Click here to visit Pediatric Diabetes website.
Toxic shock syndrome associated with newly-diagnosed type 1 diabetes
Couper J, Pollard A, Kallincos N, Colman PG, Honeyman MC, Harrison LC, Rischmueller M
J Pediatr Child Health 36: 279-282 (2000)
Studies of two post-mortem pancreata of children at the onset of type I diabetes have suggested activation and expansion of islet infiltrating T cells by a superantigen. We present the first reported case of a superantigen mediated disease, toxic shock syndrome (TSS), occurring at the diagnosis of type I diabetes. A 12-year-old girl presented with TSS and newly diagnosed diabetes with ketoacidosis. At presentation she was unconscious, febrile and hypotensive, with a desquamating erythematous rash and Kussmaul breathing. During resuscitation, her renal impairment, diarrhoea, thrombocytopaenia and ketoacidosis resolved. Vaginal discharge and blood cultures grew Staphylococcus aureus. T cell studies at 2 weeks after diagnosis detected a high level of spontaneous and islet antigen-specific proliferation with associated interleukin-10 production compared to human leucocyte antigen DR matched controls.
Click here to visit J Pediatr Child Health website
Gamma delta T cells as mediators of mucosal tolerance: the autoimmune diabetes model
Hänninen A, Harrison LC
Immunol Rev 173:109-119 (2000)
Mucosal delivery of soluble antigen induces systemic tolerance and has been applied to the prevention of autoimmune diseases. We have studied mucosal tolerance in autoimmune diabetes using the non-obese diabetic mouse model. Treatment of prediabetic mice with the pancreatic islet autoantigen insulin, by aerosol or intranasal delivery, reduces the incidence of diabetes and is associated with induction of CD8 (alpha alpha) gamma delta T cells, small numbers of which prevent adoptive transfer of diabetes. We examine the evidence for gamma delta T cells in mucosal tolerance and discuss possible mechanisms underlying the induction and action of insulin-induced CD8 gamma delta regulatory T cells. CD8 gamma delta cells constitute the most abundant subpopulation of intraepithelial lymphocytes (IELs), the major lymphoid cell compartment and first line of cellular immune defence in the mucosa. Induction of regulatory CD8 gamma delta T cells requires conformationally intact but not biologically active insulin. In contrast, intranasal (pro)insulin peptide, or oral insulin which is degraded in the gut, induces CD4 regulatory cells. Regulatory gamma delta T cells secrete interleukin-10 in pancreatic lymph nodes, which could account for the antidiabetic and bystander suppressor effect of naso-respiratory insulin. The physiological role of gamma delta IELs in maintaining peripheral self-tolerance deserves further study.
Click here to visit Immunol Rev website.
Novel therapeutic strategies in autoimmune diseases: antige-specific
Harrison LC, Hafler DA
Curr Opin Immunol 12: 704-711 (2000)
The application of self-antigens as therapeutic tools is validated in inbred animal models of autoimmune disease. Mechanisms of antigen-induced tolerance (apoptosis, anergy, regulatory T cells and immune deviation) are being clarified in relation to the properties of antigens and the modes and routes of their delivery. Mucosa-mediated tolerance remains the predominant mode of antigen-specific therapy but awaits demonstration of clinical efficacy in human autoimmune disease.
Click here to visit Curr Opin Immunol website.
Association between rotavirus infection and pancreatic islet autoimmunity in children at-risk for type 1 diabetes
Honeyman MC, Coulson BS, Stone NL, Gellert SA, Goldwater PN, Steele CE, Couper JJ, Tait BD, Colman PG, Harrison LC
Diabetes 49:1319-1324 (2000)
Pancreatic islet autoimmunity leading to type 1 diabetes could be triggered by viruses in genetically susceptible individuals. Rotavirus (RV), the most common cause of childhood gastroenteritis, contains peptide sequences highly similar to T-cell epitopes in the islet autoantigens GAD and tyrosine phosphatase IA-2 (IA-2), suggesting T-cells to RV could trigger islet autoimmunity by molecular mimicry. We therefore sought an association between RV infection and islet autoantibody markers in children at risk for diabetes who were followed from birth. There was a specific and highly significant association between RV seroconversion and increases in any of these antibodies: 86% of antibodies to IA-2, 62% to insulin, and 50% to GAD first appeared or increased with increases in RV IgG or IgA. RV infection may therefore trigger or exacerbate islet autoimmunity in genetically susceptible children.
Download full text of article here.
A novel subtype of type 1 diabetes mellitus.
Honeyman MC, Coulson BS, Harrison LC
N Engl J Med 342: 1835-1837 (2000)
To the Editor:
Imagawa and colleagues (Feb. 3 issue) provide evidence that an acute insult to the exocrine
pancreas, possibly caused by a virus, may trigger type 1 diabetes mellitus. In a subgroup of adult
Japanese patients presenting with type 1 diabetes, they found T-lymphocyte infiltration in the
exocrine pancreas but no circulating antibodies to islet-cell antigens characteristic of autoimmune
diabetes. These patients had an acute onset of hyperglycemia and normal glycosylated hemoglobin
values, suggesting that the loss of beta cells was rapid and occurred before the onset of antibody
production. However, the authors found no clinical or laboratory evidence of infection...
