A selective CD28 antagonist and rapamycin synergise to protect against spontaneous autoimmune diabetes in NOD mice
The CD28/B7 interaction is critical for both effector T cell activation and forkhead box P3 (FOXP3)+ regulatory T cell (Treg) generation and homeostasis, which complicates the therapeutic use of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4)–immunoglobulin fusion protein (CTLA-4Ig) in autoimmunity. Here, we evaluated the impact of a simultaneous and selective blockade of the CD28 and mammalian target of rapamycin (mTOR) pathways in the NOD mouse model of type 1 diabetes.
NOD mice were treated with PEGylated anti-CD28 Fab′ antibody fragments (PV1-polyethylene glycol [PEG], 10 mg/kg i.p., twice weekly), rapamycin (1 mg/kg i.p., twice weekly) or a combination of both drugs. Diabetes incidence, pancreatic islet infiltration and autoreactive T cell responses were analysed.
We report that 4 week administration of PV1-PEG combined with rapamycin effectively controlled the progression of autoimmune diabetes in NOD mice at 10 weeks of age by reducing T cell activation and migration into the pancreas. Treatment with rapamycin alone was without effect, as was PV1-PEG monotherapy initiated at 4, 6 or 10 weeks of age. Prolonged PV1-PEG administration (for 10 weeks) accelerated diabetes development associated with impaired peripheral Treg homeostasis. This effect was not observed with the combined treatment.
CD28 antagonist and rapamycin treatment act in a complementary manner to limit T cell activation and infiltration of pancreatic islets and diabetes development. These data provide new perspectives for the treatment of autoimmune diabetes and support the therapeutic potential of protocols combining antagonists of CD28 (presently in clinical development) and the mTOR pathway.
KeywordsCD28 antagonist Combination therapy NOD mice Rapamycin Type 1 diabetes
Cytotoxic T lymphocyte-associated antigen 4
Cytotoxic T lymphocyte-associated antigen 4–immunoglobulin fusion protein
Experimental autoimmune encephalomyelitis
Experimental autoimmune uveitis
Forkhead box P3
Islet-specific glucose-6-phosphatase catalytic-subunit-related protein
Mammalian target of rapamycin
PEGylated CD28-specific Fab′ fragments
T cell receptor
Effector T cell
Regulatory T cell
Violet Proliferation Dye
The authors thank M. Bellanger, E. Panafieu and S. Fonlebeck (Inserm U1151, Paris, France) for mouse production and housing.
AB and TG designed experiments, acquired and analysed data and wrote part of the manuscript. FV and CM designed and performed experiments and analysed data. BV contributed to the conception and design of the study, provided PV1-PEG and reviewed the manuscript. LC contributed to the design of the study and interpretation of data, and helped write the manuscript. SY designed and directed the study, analysed the data and wrote the manuscript. All authors revised the manuscript and approved the final version to be published. SY is the guarantor of this work.
This work was supported by grants from the European Commission (FP7, TRIAD project: Tolerance restoration in autoimmune diseases by selective manipulation of the CD28 costimulatory pathway), by institutional funding from Inserm and University Paris Descartes and by Fondation Day Solvay. AB was supported by a doctoral fellowship from Inserm and a grant from the Société Française d’Endocrinologie et Diabétologie Pédiatrique (grant from Novo Nordisk).
Duality of interest
BV and CM are current employees of OSE Immunotherapeutics (formerly Effimune SAS). The pegylated anti-CD28 Fab′ antibody fragment (PV1-PEG) is the property of OSE Immunotherapeutics, Nantes, France. AB, FV, TG, LC and SY declare no commercial or financial conflict of interest. The study sponsor was not involved in: the design of the study; the collection, analysis or interpretation of data; writing the report; or the decision to submit the report for publication.