Insulin-Fc fusions and methods of use
The present disclosure relates generally to compositions of insulin-Fc (e.g., proinsulin-Fc) fusion proteins and their use to treat autoimmune disease, e.g., autoimmune diabetes, e.g., Type 1 diabetes.
1. An insulin-Fc fusion protein for treating or preventing autoimmune diabetes in a subject, said insulin-Fc fusion protein comprising an insulin polypeptide fused to a Fc domain, wherein the insulin polypeptide comprises a B-chain peptide, a C-chain peptide, and an A-chain peptide, wherein the amino acid sequence of the C-chain peptide is AAK, and wherein the B-chain peptide comprises the amino acid sequence FVNQHLCGSHLVX 1 ALX 2 LVCGEX 3 GFFYTPK (SEQ ID NO: 28), wherein X 1 is E or Q, X 2 is Y or A, and X 3 is R or E,
wherein said insulin-Fc fusion protein binds human insulin receptor at an IC 50 >3,000 nM in a competitive binding assay; and
inhibits in vitro binding of insulin+ B cell receptors to insulin at an IC 50 <300 nM.
2. The insulin-Fc fusion protein of claim 1 , wherein the Fc domain comprises a wild-type Fc fragment of human IgG1, and wherein the amino acid sequence of the Fc domain comprises SEQ ID NO: 22.
3. The insulin-Fc fusion protein of claim 2 , wherein the insulin-Fc fusion protein inhibits in vitro binding of insulin+ B cell receptors to insulin at an IC 50 ≤100 nM.
4. The insulin-Fc fusion protein of claim 2 , wherein the insulin-Fc fusion protein activates T-cells to secrete IL-2 levels that are reduced compared to that observed in T-cells activated by recombinant human insulin.
5. The insulin-Fc fusion protein of claim 2 , wherein the amino acid sequence of the A-chain peptide comprises SEQ ID NO: 19.
6. The insulin-Fc fusion protein of claim 2 , wherein the insulin polypeptide is fused to the Fc fragment via a peptide linker, and wherein the amino acid sequence of the peptide linker is selected from the group consisting of SEQ ID NO: 20 and SEQ ID NO: 21.
7. The insulin-Fc fusion protein of claim 2 , wherein the amino acid sequence of the insulin-Fc fusion protein is SEQ ID NO: 3.
8. A method for treating or preventing autoimmune diabetes in a subject in need thereof comprising administering to the subject an effective amount of the insulin-Fc fusion protein of claim 1 , wherein autoimmune diabetes is selected from the group consisting of Type 1 diabetes, juvenile diabetes, insulin-dependent diabetes, and latent autoimmune diabetes;
wherein the subject has been diagnosed with or is at risk for autoimmune diabetes; and
wherein the subject is not hyperglycemic.
9. The method of claim 8 , wherein the subject has detectable levels of at least one autoimmune antibody selected from the group consisting of an insulin autoantibody (IAA), an anti-glutamic acid decarboxylase (GAD) antibody, and an anti-islet antigen-2 (IA-2) antibody, and wherein the subject has detectable levels of an insulin-specific B cell population.
10. The method of claim 8 , wherein the subject harbors one or more human leukocyte antigen (HLA) haplotypes selected from the group consisting of: (a) DRB1*0301-DQA1*0501-DQB1*0201; (b) DRB1*0405-DQA1*0301-DQB1*0302; (c) DRB1*0401-DQA1*0301-DQB*0302; (d) DRB1*0402-DQA1*0301-DQB1*0302; (e) DRB1*0404-DQA1*0301-DQB1*0302; and (f) DRB1*0801-DQB1*0401-DQB1*0402.
11. The method of claim 8 , wherein the subject displays a reduction in the number of anti-insulin B cells after at least one administration of the insulin-Fc fusion protein compared to that observed in the subject prior to the at least one administration, wherein the subject displays decreased levels of insulin autoantibody after at least one administration of the insulin-Fc fusion protein compared to that observed in the subject prior to the at least one administration; and
wherein blood glucose levels of the subject after at least one administration of the insulin-Fc fusion protein are comparable to that observed in the subject prior to the at least one administration.
12. The insulin-Fc fusion protein of claim 1 , wherein the insulin-Fc fusion protein inhibits in vitro binding of insulin+ B cell receptors to insulin at an IC 50 ≤100 nM.
13. The insulin-Fc fusion protein of claim 1 , wherein the insulin-Fc fusion protein activates T-cells to secrete IL-2 levels that are reduced compared to that observed in T-cells activated by recombinant human insulin.
14. The insulin-Fc fusion protein of claim 1 , wherein the amino acid sequence of the A-chain peptide comprises SEQ ID NO: 19.
15. The insulin-Fc fusion protein of claim 1 , wherein the insulin polypeptide is fused to the Fc fragment via a peptide linker, and wherein the amino acid sequence of the peptide linker is selected from the group consisting of SEQ ID NO: 20 and SEQ ID NO: 21.
16. The insulin-Fc fusion protein of claim 1 , wherein the amino acid sequence of the insulin-Fc fusion protein is SEQ ID NO: 3.
17. The insulin-Fc fusion protein of claim 1 , wherein said insulin-Fc fusion protein is metabolically inactive.
18. The insulin-Fc fusion protein of claim 1 , wherein said insulin-Fc fusion protein does not interact with insulin-hormone receptor in vivo.
19. The insulin-Fc fusion protein of claim 1 , wherein said insulin-Fc fusion protein binds human insulin receptor at an IC 50 >5,000 nM in a competitive binding assay.