Expansion of Th17 cells and functional defects in T regulatory cells are key features of the pancreatic lymph nodes in patients with type 1 diabetes
- Diabetes. 2011 Nov;60(11):2903-13. doi: 10.2337/db11-0090.
- 1. Diabetes Research Institute, San Raffaele Scientific Institute, Milan, Italy.
Objective: Autoimmune diseases, including Type 1 Diabetes, are thought to have a Th17-cell bias and/or a T-regulatory cell (Treg) defect. Understanding whether this is a hallmark of patients with Type 1 Diabetes is a crucial question that is still unsolved, largely due to the difficulties of accessing tissues targeted by the disease.
Research design and methods: We phenotypically and functionally characterized Th17 cells and Tregs residing in the pancreatic-draining Lymph Nodes (PLNs) of 19 patients with Type 1 Diabetes and 63 nondiabetic donors and those circulating in the peripheral blood of 14 type 1 diabetic patients and 11 healthy subjects.
Results: We found upregulation of Th17 immunity and functional defects in CD4(+)CD25(bright) Tregs in the PLNs of type 1 diabetic subjects but not in their peripheral blood. In addition, the proinsulin-specific Treg-mediated control was altered in the PLNs of diabetic patients. The dysfunctional Tregs isolated from diabetic subjects did not contain contaminant effector T cells and were all epigenetically imprinted to be suppressive, as defined by analysis of the Treg-specific demethylated region within the forkhead box P3 (FOXP3) locus.
Conclusions: These data provide evidence for an unbalanced immune status in the PLNs of type 1 diabetic subjects, and treatments restoring the immune homeostasis in the target organ of these patients represent a potential therapeutic strategy.