Dynamic Immune Phenotypes of B and T Helper Cells Mark Distinct Stages of T1D Progression.

Multiple studies of B- and T-cell compartments and their response to stimuli demonstrate alterations in established type 1 diabetes (T1D). Yet it is not known whether these alterations reflect immune mechanisms that initiate islet autoimmunity, promote disease progression, or are secondary to disease. To address these questions, we used samples from the TrialNet Pathway to Prevention study to investigate T-cell responses to interleukin (IL)-2 and regulatory T cell-mediated suppression, the composition of the B-cell compartment, and B-cell responses to B-cell receptor and IL-21 receptor engagement. These studies revealed stage-dependent T- and B-cell functional and immune phenotypes; namely, early features that differentiate autoantibody-positive at-risk first-degree relatives (FDRs) from autoantibody-negative FDRs and persisted through clinical diagnosis; late features that arose at or near T1D diagnosis; and dynamic features that were enhanced early and blunted at later disease stages, indicating evolving responses along the continuum of T1D. We further explored how these specific phenotypes are influenced by therapeutic interventions. Our integrated studies provide unique insights into stable and dynamic stage-specific immune states and define novel immune phenotypes of potential clinical relevance.

Rapamycin/IL-2 combination therapy in patients with type 1 diabetes augments Tregs yet transiently impairs ß-cell function.

Rapamycin/interleukin-2 (IL-2) combination treatment of NOD mice effectively treats autoimmune diabetes. We performed a phase 1 clinical trial to test the safety and immunologic effects of rapamycin/IL-2 combination therapy in type 1 diabetic (T1D) patients. Nine T1D subjects were treated with 2-4 mg/day rapamycin orally for 3 months and 4.5 × 10(6) IU IL-2 s.c. three times per week for 1 month. ß-Cell function was monitored by measuring C-peptide. Immunologic changes were monitored using flow cytometry and serum analyses. Regulatory T cells (Tregs) increased within the first month of therapy, yet clinical and metabolic data demonstrated a transient worsening in all subjects. The increase in Tregs was transient, paralleling IL-2 treatment, whereas the response of Tregs to IL-2, as measured by STAT5 phosphorylation, increased and persisted after treatment. No differences were observed in effector T-cell subset frequencies, but an increase in natural killer cells and eosinophils occurred with IL-2 therapy. Rapamycin/IL-2 therapy, as given in this phase 1 study, resulted in transient ß-cell dysfunction despite an increase in Tregs. Such results highlight the difficulties in translating therapies to the clinic and emphasize the importance of broadly interrogating the immune system to evaluate the effects of therapy.

ECM components guide IL-10 producing regulatory T-cell (TR1) induction from effector memory T-cell precursors.

We describe a role for ECM as a biosensor for inflammatory microenvironments that plays a critical role in peripheral immune tolerance. We show that hyaluronan (HA) promotes induction of Foxp3- IL-10-producing regulatory T cells (TR1) from conventional T-cell precursors in both murine and human systems. This is, to our knowledge, the first description of an ECM component inducing regulatory T cells. Intact HA, characteristic of healing tissues, promotes induction of TR1 capable of abrogating disease in an IL-10-dependent mouse colitis model whereas fragmentary HA, typical of inflamed tissues, does not, indicating a decisive role for tissue integrity in this system. The TR1 precursor cells in this system are CD4(+)CD62L(-)FoxP3(-), suggesting that effector memory cells assume a regulatory phenotype when they encounter their cognate antigen in the context of intact HA. Matrix integrity cues might thereby play a central role in maintaining peripheral tolerance. This TR1 induction is mediated by CD44 cross-linking and signaling through p38 and ERK1/2. This induction is suppressed, also in a CD44-dependent manner, by osteopontin, a component of chronically inflamed ECM, indicating that CD44 signaling serves as a nexus for fate decisions regarding TR1 induction. Finally, we demonstrate that TR1 induction signals can be recapitulated using synthetic matrices. These results reveal important roles for the matrix microenvironment in immune regulation and suggest unique strategies for immunomodulation.