Metabolically inactive insulin analogue does not prevent autoimmune diabetes in NOD mice

Abstract

Aims/hypothesis Insulin is widely considered to be a driver antigen in type 1 diabetes in humans and in mouse models of the disease. Therefore, insulin or insulin analogues are candidates for tolerogenic drugs to prevent disease onset in individuals with risk of diabetes. Previous experiments have shown that autoimmune diabetes can be prevented in NOD mice by repeated doses of insulin administered via an oral, nasal or parenteral route, but clinical trials in humans have not succeeded. The hypoglycaemic activity of insulin is dose-limiting in clinical studies attempting tolerance and disease prevention. Here, we aimed to investigate the therapeutic potential of metabolically inactive insulin analogue (MII) in NOD mice. Methods The tolerogenic potential of MII to prevent autoimmune diabetes was studied by administering multiple i.v. or s.c. injections of MII to non-diabetic 7–12-week-old female NOD mice in three geographical colony locations. The incidence of diabetes was assessed from daily or weekly blood glucose measurements. The effect of MII on insulin autoantibody levels was studied using an electrochemiluminescence-based insulin autoantibody assay. The effect on the number of insulin-reactive CD8+ and CD4+ T lymphocytes in peripheral lymphoid tissue was studied with MHC-I and MHC-II tetramers, respectively. Results We found that twice-weekly s.c. administration of MII accelerates rather than prevents diabetes. High-dose i.v. treatment did not prevent disease or affect insulin autoantibody levels, but it increased the amount of insulin-reactive CD4+ T lymphocytes in peripheral lymphoid tissue. Conclusions/interpretation Our data suggest that parenteral MII, even when used in high doses, has little or no therapeutic potential in NOD mice and may exacerbate disease.

Revealing the specificity of regulatory T cells in murine autoimmune diabetes

“…Another TCR, 510, responded to immobilized insulin B:9-23 p8E and p8G tetramers (29) ( Fig. 3C and to other insulin epitopes, we stimulated the hybridomas with splenic DCs pulsed with metabolically inactive human insulin, B25Dinsulin (43). The use of B25D-insulin avoided the hormonal activation of the hybridomas that altered the assay background.…”

The Development of Immunotherapy Strategies for the Treatment of Type 1 Diabetes

“…Our negative oral insulin findings do not stand in isolation within the field of antigenic therapies for T1D. In collaboration with the Lenardo lab, we found no support for the tolerizing effect of parenteral, metabolically inactive insulin as had previously been reported ( 48 ). Likewise, published data on disease prevention using a strong agonist insulin mimetope did not appear to be reproducible ( 49 ).…”

Oral insulin does not alter gut microbiota composition of NOD mice

“…As an example, oral insulin has been found to significantly decrease the incidence of diabetes in NOD mice, when administered 1 mg of porcine insulin biweekly from 5 weeks of age, for 5 weeks and subsequently weekly until 30 weeks—1 year of age . Reproduction of the study has, however, been unsuccessful and so were we, despite the age of initiation (4 weeks of age vs 5 weeks of age) as the only alteration. The therapeutic effect of the oral insulin is not a part of this study, as the mice were euthanized when diabetic.…”

“…An oral route of insulin delivery has the theoretical ability to improve imitation of the endogenous insulin pathways in the body and significantly reduce the risk of hypoglycaemia with improved glucose homeostasis . However, the efficacy of oral insulin in preventing or postponing the development of T1D‐developing nonobese diabetic (NOD) mice has been inconsistent, and a fully established oral treatment is yet to come. Still, despite drawbacks, and the complex and challenging task of producing oral insulins, the research in the field is intense and widespread .…”