Introduction of beta cell auto-antigens via the gut through Lactococcus lactis (L. lactis) has been demonstrated to be a promising approach for diabetes reversal in NOD mice. Here we show that a combination of low-dose anti-CD3 with a clinical-grade self-containing L. lactis appropriate for human application secreting human pro-insulin and IL10 cured 66% of new-onset diabetic mice, comparable to plasmid-driven L. lactis. Initial blood glucose concentrations (<350 mg/dl) and insulin autoantibody positivity were predictors of stable reversal of hyperglycemia and decline in IAA positivity was an immune biomarker of therapeutic outcome. Assessment of the immune changes induced by the L. lactis-based therapy revealed elevated frequencies of CD4+Foxp3+ T cells in the pancreatic draining lymph nodes, pancreas, and peripheral blood of all treated mice, independent of metabolic outcome. Neutralization of CTLA4 and TGF-β partially abrogated the suppressive function of therapy-induced Tregs. Ablation or functional impairment of Foxp3+ Tregs in vivo at start or stop of therapy impaired immune tolerance, highlighting the dependence of the therapy-induced tolerance in new-onset diabetic mice on the presence and functionality of CD4+Foxp3+ T cells. Biomarkers identified in this study can potentially be used in the future to tailor the L. lactis-based combination therapy for individual patients.
a current address: Instituto de Ciências Biomédicas. Universidade de São Paulo (USP), São Paulo, Brazil.
b T.T and D.P.C share first authorship;
c C.G. and C.M. share senior authorship.
This article contains Supplementary Data online at http://diabetes.diabetesjournals.org/lookup/suppl/doi:10.2337/db15-1625/-/DC1.
- Received November 26, 2015.
- Accepted October 29, 2016.
- © 2016 by the American Diabetes Association.