Tolerogenic Dendritic Cells from Poorly Compensated Type 1 Diabetes Patients Have Decreased Ability To Induce Stable Antigen-Specific T Cell Hyporesponsiveness and Generation of Suppressive Regulatory T Cells

Tolerogenic dendritic cells (toIDCs) may offer an interesting intervention strategy to re-establish Ag-specific tolerance in autoimmune diseases, including type 1 diabetes (T1D). T1D results from selective destruction of insulin-producing beta cells leading to hyperglycemia that, in turn, specifically affects a patient's immune system. In this study, we prepared monocyte-derived toIDCs modulated by dexamethasone and vitamin D2 from 31 T1D patients with optimal glycemic control and 60 T1D patients with suboptimal glycemic control and assessed their tolerogenic properties in correlation with metabolic state of patients. toIDCs differentiated from both groups of patients acquired a regulatory phenotype and an anti-inflammatory profile. Interestingly, toIDCs from well-controlled patients expressed higher levels of inhibitory molecules IL-T3 and PD-L1. Additionally, glutamic acid decarboxylase (GAD) 65-loaded toIDCs from well-controlled patients decreased significantly primary Th1/Th17 responses, induced stable GAD65-specific T cell hyporesponsiveness, and suppressed markedly control DC-induced GAD65-specific T cell activation compared with poorly controlled patients. The ability of toIDCs from poorly controlled patients to induce durable GAD65-specific T cell hyporesponsiveness was reversed once the control of glycemia improved. In both groups of patients, toIDCs were able to induce regulatory T cells from autologous naive CD4(+) T cells. However, regulatory T cells from well-controlled patients had better suppressive abilities. The functionality of toIDCs was confirmed in the adoptive transfer model of NOD-SCID mice where toIDCs delayed diabetes onset. These results suggest that metabolic control of T1D affects the functional characteristics of toIDCs and subsequent effector T cell responses. Metabolic control may be relevant for refining inclusion criteria of clinical trials in the settings of T1D.