Regulatory T cells in diabetes and gastritis

Patients with Type 1 diabetes mellitus (T1D) have an increased prevalence of associated organ-specific autoimmune diseases such as pernicious anemia whose histological substrate is a chronic atrophic gastritis (CAG). Latent pernicious anemia precedes clinically-manifest pernicious anemia and may be difficult to detect solely on simple analytical grounds. We recently described an increased prevalence of clinically-latent pernicious anemia in T1D using low concentrations of pepsinogen I, a zymogen of pepsin present in gastric mucosa, as a useful additional diagnostic marker, besides parietal cell antibodies, for screening latent pernicious anemia in T1D. The failure of peripheral tolerance mechanisms such as regulatory T cells (Treg) might be involved in CAG development in T1D patients. Indeed, functional defects in Tregs have been described in T1D patients. To this end, the percentage of Tregs in peripheral blood of T1D-CAG patients was analyzed and compared with those of a group of T1D without associated autoantibodies and a healthy control group. Tregs levels were also analyzed in gastric biopsies of T1D-CAG patients. The results obtained have led to new questions regarding the pathogenic mechanisms implicated in the development of associated autoimmune diseases in T1D.