Interleukin-2/interleukin-2 receptor alpha fusion proteins and methods of use

Abstract

Various methods and compositions are provided which can be employed to modulate the immune system. Compositions include a fusion protein comprising: (a) a first polypeptide comprising Interleukin-2 (IL-2) or a functional variant or fragment thereof; and (b) a second polypeptide, fused in frame to the first polypeptide, wherein the second polypeptide comprises an extracellular domain of Interleukin-2 Receptor alpha (IL-2Rα) or a functional variant or fragment thereof, and wherein the fusion protein has IL-2 activity. Various methods are provided for modulating the immune response in a subject comprising administering to a subject in need thereof a therapeutically effective amount of the IL-2/IL-2Rα fusion protein disclosed herein.

1 . A fusion protein comprising:
 (a) a first polypeptide comprising Interleukin-2 (IL-2) or a functional variant or fragment thereof; and   (b) a second polypeptide, fused in frame to said first polypeptide, said second polypeptide comprises an extracellular domain of Interleukin-2 Receptor alpha (IL-2Rα) or a functional variant or fragment thereof, wherein said fusion protein has IL-2 activity.   
     
     
         2 . The fusion protein of  claim 1 , wherein said fusion protein has an increased IL-potency when compared to native or recombinant IL-2. 
     
     
         3 . The fusion protein of  claim 1 , wherein said fusion protein has an increased persistent IL-2 stimulation of IL-2R bearing lymphocytes in vivo when compared to native or recombinant IL-2. 
     
     
         4 . The fusion protein of  claim 1 , wherein
 (a) said first polypeptide comprising IL-2 shares at least 70% sequence identity to SEQ ID NO: 2; and/or   (b) said second polypeptide comprising the extracellular domain of IL-2Rα shares at least 70% sequence identity to SEQ ID NO: 7.   
     
     
         5 . The fusion protein of  claim 4 , wherein
 (a) said first polypeptide comprising IL-2 shares at least 85% sequence identity to SEQ ID NO: 2; and/or   (b) said second polypeptide comprising the extracellular domain of IL-2Rα shares at least 85% sequence identity to SEQ ID NO: 7.   
     
     
         6 . The fusion protein of  claim 1 , further comprising a linker sequence fused in frame between said first polypeptide and said second polypeptide. 
     
     
         7 . The fusion protein of  claim 6 , wherein the linker sequence comprises:
 (a) a glycine/serine linker;   (b) the sequence set forth in SEQ ID NO: 11, 12, 13, 14, 15, 40, 41, 50, 51, or 52; or   (c) a sequence having least 90% sequence identity to any one of SEQ ID NO: 11, 12, 13, 14, 15, 40, 41, 50, 51, or 52.   
     
     
         8 . The fusion protein of  claim 7 , wherein the fusion protein comprises
 (a) the amino acid sequence of any one of SEQ ID NO: 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 36, 37, 38, 39, 43, 44, 45, 46, 54, 55, 56, 57, 58, 59, 60, or 61; or   (b) a sequence having at least 80% to any one of SEQ ID NO: 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 36, 37, 38, 39, 43, 44, 45, 46, 54, 55, 56, 57, 58, 59, 60, or 61.   
     
     
         9 . The fusion protein of  claim 7 , wherein the fusion protein comprises at least one mutation in the extracellular domain of IL-2Rα. 
     
     
         10 . The fusion protein of  claim 9 , wherein the fusion protein comprises:
 (a) the amino acid sequence of any one of SEQ ID NO: 62 or 64; or   (b) a sequence having at least 80% to any one of SEQ ID NO: 62 or 64.   
     
     
         11 . A polynucleotide comprising a nucleotide sequence encoding the fusion protein of  claim 1 . 
     
     
         12 . A host cell comprising the polynucleotide of  claim 11 . 
     
     
         13 . The host cell of  claim 12 , wherein the host cell comprises a CHO cell or a COS cell. 
     
     
         14 . A method for making a fusion protein of  claim 1 , said method comprising introducing into a host cell a polynucleotide encoding the fusion protein of  claim 1  and expressing the fusion protein in the host cell. 
     
     
         15 . The method of  claim 14 , wherein the polynucleotide encoding the fusion protein is operably linked to a promoter active in the host cell. 
     
     
         16 . A method for decreasing the immune response in a subject comprising administering to a subject in need of a decrease in the immune response a therapeutically effective amount of the fusion protein of  claim 1 . 
     
     
         17 . The method of  claim 16 , wherein said subject has an autoimmune disease. 
     
     
         18 . The method of  claim 17 , wherein said autoimmune disease comprises type 1 diabetes, multiple sclerosis, rheumatoid arthritis, celiac disease, systemic lupus erythematous, juvenile idiopathic arthritis, Crohn's disease, ulcerative colitis or systemic sclerosis, graft versus host disease, psoriasis, alopecia areata, or HCV-induced vasculitis. 
     
     
         19 . The method of  claim 16 , wherein the therapeutically effective amount of the fusion protein comprises 10 3  to 10 6  IU of IL-2 activity per adult or 10 4 ±100 fold of IL-2 activity per adult to decrease an immune response. 
     
     
         20 . A method for increasing the immune response in a subject comprising administering to a subject in need of an increase in the immune response a therapeutically effective amount of the fusion protein of  claim 1 . 
     
     
         21 . A method of enhancing the immunogenicity of a vaccine in a subject, comprising:
 (a) administering to the subject a therapeutically effective amount of the fusion protein of  claim 1 ; and,   (b) administering to the subject a vaccine,   wherein said fusion protein enhances the immunogenicity of the vaccine.   
     
     
         22 . A method of overcoming a suppressed immune response to a vaccine in a subject, comprising:
 (a) administering to the subject a therapeutically effective amount of the fusion protein of  claim 1 ; and,   (b) administering to the subject a vaccine,   wherein said fusion protein overcomes said suppressed immune response to said vaccine.   
     
     
         23 . The method of  claim 21 , wherein administration of said therapeutically effective amount of the fusion protein and administration of said vaccine is sequential, in any order. 
     
     
         24 . The method of  claim 21 , wherein administration of said therapeutically effective amount of said fusion protein and administration of the vaccine is simultaneous. 
     
     
         25 . The method of  claim 21 , wherein said vaccine is a cancer vaccine. 
     
     
         26 . The method of  claim 21 , wherein the therapeutically effective amount of the fusion protein comprises at least 10 4  to 10 7  IU of IL-2 activity per adult or at least 10 5 ±10 of IL-2 activity per adult to increase an immune response. 
     
     
         27 . The method of  claim 14 , wherein said subject is a human. 
     
     
         28 . The method of  claim 14 , wherein said subject is a domesticated mammal or an agricultural mammal.