Protection against Autoimmune Diabetes by Silkworm-Produced GFP-Tagged CTB-Insulin Fusion Protein

• Published in: Clinical & developmental immunology 2011-01, Vol.2011 (2011), p.1-14
• Main Authors: Jin, Yongfeng, Shi, Xiaowen, Wang, Wenfeng, Meng, Qiaohong, Zhang, Yaozhou
• Format: Article
• Language: English
• Subjects: Administration, Oral; Adoptive Transfer - methods; Animals; Autoantigens - administration & dosage; Autoantigens - immunology; Baculoviridae; Blotting, Western; Bombyx; Cholera Toxin - administration & dosage; Cholera Toxin - immunology; Diabetes Mellitus, Type 1 - immunology; Diabetes Mellitus, Type 1 - mortality; Diabetes Mellitus, Type 1 - pathology; Diabetes Mellitus, Type 1 - prevention & control; Diabetes Mellitus, Type 1 - therapy; Disease-Free Survival; Female; Genetic Vectors; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - immunology; Green Fluorescent Proteins - metabolism; Immune Tolerance; Immunization; Insulin - administration & dosage; Insulin - immunology; Mice; Mice, Inbred NOD; Mice, SCID; Recombinant Fusion Proteins - administration & dosage; Recombinant Fusion Proteins - biosynthesis; Recombinant Fusion Proteins - immunology; Spleen - immunology; Spleen - metabolism; Spleen - pathology; T-Lymphocytes, Regulatory - immunology
• ISSN: 2314-8861; 1740-2522; 2314-7156; 1740-2530
• DOI: 10.1155/2011/831704

In animals, oral administration of the cholera toxin B (CTB) subunit conjugated to the autoantigen insulin enhances the specific immune-unresponsive state. This is called oral tolerance and is capable of suppressing autoimmune type 1 diabetes (T1D). However, the process by which the CTB-insulin (CTB-INS) protein works as a therapy for T1D in vivo remains unclear. Here, we successfully expressed a green fluorescent protein- (GFP-) tagged CTB-Ins (CTB-Ins-GFP) fusion protein in silkworms in a pentameric form that retained the native ability to activate the mechanism. Oral administration of the CTB-Ins-GFP protein induced special tolerance, delayed the development of diabetic symptoms, and suppressed T1D onset in nonobese diabetic (NOD) mice. Moreover, it increased the numbers of CD4+CD25+Foxp3+ T regulatory (Treg) cells in peripheral lymph tissues and affected the biological activity of spleen cells. This study demonstrated that the CTB-Ins-GFP protein produced in silkworms acted as an oral protein vaccine, inducing immunological tolerance involving CD4+CD25+Foxp3+ Treg cells in treating T1D.