Low doses of anti-CD3, ciclosporin A and the vitamin D analogue, TX527, synergise to delay recurrence of autoimmune diabetes in an islet-transplanted NOD mouse model of diabetes

• Published in: Diabetologia Vol. 55; no. 10; pp. 2723 - 2732
• Main Authors: Baeke, F., Van Belle, T. L., Takiishi, T., Ding, L., Korf, H., Laureys, J., Gysemans, C., Mathieu, C.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01-10-2012; Springer; Springer Nature B.V
• Subjects: Alkynes - therapeutic use; Allografts; Animal models; Animals; Antibodies, Monoclonal - immunology; Antibodies, Monoclonal - therapeutic use; Antigens; Autoimmune diseases; Beta cells; Biological and medical sciences; Calcium; CD3 Complex - immunology; Cell Proliferation; Cholecalciferol - therapeutic use; Clinical trials; Cyclosporine - therapeutic use; Cytokines; Cytotoxicity; Diabetes; Diabetes mellitus; Diabetes Mellitus, Type 1 - immunology; Diabetes Mellitus, Type 1 - pathology; Diabetes Mellitus, Type 1 - prevention & control; Diabetes Mellitus, Type 1 - surgery; Diabetes. Impaired glucose tolerance; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Synergism; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Female; Flow cytometry; Human Physiology; Immunofluorescence; Immunological memory; Immunomodulation; Immunoregulation; Immunotherapy; Inflammation; Internal Medicine; Islet cells; Islets of Langerhans; Islets of Langerhans Transplantation - immunology; Islets of Langerhans Transplantation - pathology; Lymphocytes T; Male; Medical sciences; Medicine; Medicine & Public Health; Memory cells; Metabolic Diseases; Mice; Mice, Inbred NOD; Microscopy; Monoclonal antibodies; Pancreas; Phenotyping; Polymerase chain reaction; Secondary Prevention; Side effects; Syngeneic grafts; T-Lymphocytes - pathology; Transplantation; Transplants & implants; Vitamin D; Vitamin D - analogs & derivatives; Vitamin D3; Autoimmunity; T helper skewing; Combination therapy; Regulatory T cells; T cells; Type 1 diabetes; Endocrinopathy; Immunopathology; Animal model; Low dose; Rodentia; Autoimmune disease; Transplantation; Micronutrient; Vertebrata; Mammalia; Mouse; Vitamin D; Animal; T-Lymphocyte
• ISSN: 0012-186X; 1432-0428
• DOI: 10.1007/s00125-012-2630-1

Aims/hypothesis
Anti-CD3 monoclonal antibodies remain the most promising immune therapy for reversing recent-onset type 1 diabetes. However, current clinical trials have revealed their major drawback, namely the narrow therapeutic window in which low doses are ineffective and higher doses that preserve functional beta cell mass cause side effects. Strategies that sidestep these limitations while preserving or improving anti-CD3’s therapeutic efficiency are essential. We hypothesised that combining a potent vitamin D
3
analogue (TX527), ciclosporin A (CsA) and anti-CD3 would act to lower the dose while maintaining or even boosting therapeutic efficacy to counteract autoimmune destruction of transplanted islets.
Methods
This study involved the use of syngeneic islet transplantation, immunofluorescence microscopy, immune phenotyping by flow cytometry, RT-PCR analysis, and in vitro and in vivo suppression assays.
Results
Combination therapy with TX527, CsA and anti-CD3 was well tolerated on the basis of weight, bone and calcium variables. Remarkably, combining all three agents at sub-therapeutic doses greatly reduced recurrent autoimmune responses to a grafted islet mass (mean ± SEM: 79.5 ± 18.6 days;
p
 < 0.01), by far exceeding the therapeutic efficacy of monotherapy (24.8 ± 7.3 days for anti-CD3) and dual therapy (25.5 ± 12.4 days for anti-CD3+CsA). Combination therapy surpassed anti-CD3 monotherapy in reducing islet infiltration by effector/memory phenotype CD8
+
T cells, as well as by reducing proinflammatory cytokine responses and increasing the frequency of T regulatory cells that were functional in vitro and in vivo, and acted in a cytotoxic T lymphocyte antigen 4-dependent manner.
Conclusions/interpretation
Combining the immunomodulatory actions of anti-CD3 mAb with CsA and the vitamin D
3
analogue, TX527, delivers therapeutic efficacy in an islet-transplanted NOD mouse model of diabetes.