Anti-TCRß mAb in Combination With Neurogenin3 Gene Therapy Reverses Established Overt Type 1 Diabetes in Female NOD Mice.

Insulin-producing ß cells in patients with type 1 diabetes (T1D) are destroyed by T lymphocytes. We investigated whether targeting the T-cell receptor (TCR) with a monoclonal antibody (mAb) abrogates T-cell response against residual and newly formed islets in overtly diabetic nonobese diabetic (NOD) mice. NOD mice with blood glucose levels of 250 to 350 mg/dL or 350 to 450 mg/dL were considered as new-onset or established overt diabetes, respectively. These diabetic NOD mice were transiently treated with an anti-TCR ß chain (TCRß) mAb, H57-597, for 5 days. Two weeks later, some NOD mice with established overt diabetes further received hepatic gene therapy using the islet-lineage determining gene Neurogenin3 (Ngn3), in combination with the islet growth factor gene betacellulin (Btc). We found that anti-TCRß mAb (50 µg/d) reversed >80% new-onset diabetes in NOD mice for >14 weeks by reducing the number of effector T cells in the pancreas. However, anti-TCRß mAb therapy alone reversed only ∼20% established overt diabetes in these mice. Among those overtly diabetic NOD mice whose diabetes was resistant to anti-TCRß mAb treatment, ∼60% no longer had diabetes when they also received Ngn3-Btc hepatic gene transfer 2 weeks after initial anti-TCRß mAb treatment. This combination of Ngn3-Btc gene therapy and anti-TCRß mAb treatment induced the sustained formation of periportal insulin-producing cells in the liver of overtly diabetic mice. Therefore, directly targeting TCRß with a mAb potently reverses new-onset T1D in NOD mice and protects residual and newly formed gene therapy-induced hepatic neo-islets from T-cell‒mediated destruction in mice with established overt diabetes.