Insulitis in the pancreas of non-diabetic organ donors under age 25 years with multiple circulating autoantibodies against islet cell antigens

Autoantibodies against islet cell antigens are routinely used to identify subjects at increased risk of symptomatic type 1 diabetes, but their relation to the intra-islet pathogenetic process that leads to positivity for these markers is poorly understood. We screened 556 non-diabetic organ donors (3 months to 24 years) for five different autoantibodies and found positivity in 27 subjects, 25 single- and two double autoantibody-positive donors. Histopathological screening of pancreatic tissue samples showed lesion characteristic for recent-onset type 1 diabetes in the two organ donors with a high-risk profile, due to their positivity for multiple autoantibodies and HLA-inferred risk. Inflammatory infiltrates (insulitis) were found in a small fraction of islets (<5%) and consisted predominantly of CD3+CD8+ T-cells. Islets with insulitis were found in close proximity to islets devoid of insulin-positivity; such pseudo-atrophic islets were present in multiple small foci scattered throughout the pancreatic tissue or were found to be distributed with a lobular pattern. Relative beta cell area in both single and multiple autoantibody-positive donors was comparable to that in autoantibody-negative controls. In conclusion, in organ donors under age 25 years, insulitis and pseudo-atrophic islets were restricted to multiple autoantibody-positive individuals allegedly at high risk of developing symptomatic type 1 diabetes, in line with reports in older age groups. These observations may give further insight into the early pathogenetic events that may culminate in clinically overt disease.

Organ-specific autoimmunity in relation to clinical characteristics in children with long-lasting type 1 diabetes

The aim of this study was to assess the prevalence of diabetes and other organ-specific autoantibodies (Ab) associated with various autoimmune conditions, in Polish children with type 1 diabetes mellitus (T1DM).In this study 114 patients, aged 13.4 years, with mean diabetes duration 5.2 years were included. Ab to islet cell antigens: glutamic acid decarboxylase (GAD), insulinoma antigen 2 (IA-2), zinc transporter 8 (ZnT8), together with thyroid peroxidase Ab (TPO Ab), thyroglobulin Ab (Tg Ab), tissue transglutaminase Ab (tTG Ab) and 21-hydroxylase Ab (21-OH Ab) were measured.The prevalence of at least one diabetes associated Ab was found in 87%, with the highest prevalence of 64% for ZnT8 Ab. In patients with disease duration <5 years, at least one antibody was present in 90%, the most prevalent was ZnT8 Ab (72%). In patients with duration >10 years, 50% had at least one antibody. The prevalence of other than islet cell autoimmunity was high (34%). Thyroid Ab were detected in 26% patients, 42% in girls vs. 8% in boys, p<0.001. tTG Ab were found in 11% patients, with a greater prevalence in children with early onset (p=0.01). 21-OH Ab were found in 2.6% T1DM patients.Islet Ab were found in most T1DM children and remained positive even 10 years after onset. ZnT8 Ab emerged as an important marker for the diagnosis of T1DM in the Polish children. Screening for non-diabetes Ab in T1DM may be helpful in identifying subclinical cases of autoimmune thyroid, celiac or Addison’s disease (AD).

Autoimmune diagnostics in diabetes mellitus

Type 1 diabetes results from a specific destruction of the insulin-producing β-cells of the pancreas. The disease is characterized by the appearance of specific autoantibodies against islet cell antigens. Autoantibodies to insulin, glutamic acid decarboxylase, tyrosine phosphatase IA-2 and cytoplasmic islet cell antibodies are useful markers for the differential diagnosis of type 1 diabetes when clinical and metabolic criteria alone do not allow definite classification. Autoimmune diagnostics is of particular importance in adults to discriminate between type 1 and type 2 diabetes and to assess the diagnosis of latent autoimmune diabetes in adults.