Date of this Version
Plant Biotechnology Journal
Lettuce and tobacco chloroplast transgenic lines expressing the cholera toxin B subunit–human proinsulin (CTB-Pins) fusion protein were generated. CTB-Pins accumulated up to ~16% of total soluble protein (TSP) in tobacco and up to ~2.5% of TSP in lettuce. Eight milligrams of powdered tobacco leaf material expressing CTB-Pins or, as negative controls, CTB–green fluorescent protein (CTB-GFP) or interferon–GFP (IFN-GFP), or untransformed leaf, were administered orally, each week for 7 weeks, to 5-week-old female non-obese diabetic (NOD) mice. The pancreas of CTB-Pins-treated mice showed decreased infiltration of cells characteristic of lymphocytes (insulitis); insulin-producing β-cells in the pancreatic islets of CTB-Pins-treated mice were significantly preserved, with lower blood or urine glucose levels, by contrast with the few β-cells remaining in the pancreatic islets of the negative controls. Increased expression of immunosuppressive cytokines, such as interleukin-4 and interleukin-10 (IL-4 and IL-10), was observed in the pancreas of CTB-Pins-treated NOD mice. Serum levels of immunoglobulin G1 (IgG1), but not IgG2a, were elevated in CTB-Pins-treated mice. Taken together, T-helper 2 (Th2) lymphocyte-mediated oral tolerance is a likely mechanism for the prevention of pancreatic insulitis and the preservation of insulin-producing β-cells. This is the first report of expression of a therapeutic protein in transgenic chloroplasts of an edible crop. Transplastomic lettuce plants expressing CTB-Pins grew normally and transgenes were maternally inherited in T1 progeny. This opens up the possibility for the low-cost production and delivery of human therapeutic proteins, and a strategy for the treatment of various other autoimmune diseases.
This is the peer reviewed version of the following article: Ruhlman, T., Ahangari, R., Devine, A., Samsam, M., & Daniell, H. (2007). Expression of cholera toxin B–proinsulin fusion protein in lettuce and tobacco chloroplasts – oral administration protects against development of insulitis in non-obese diabetic mice. Plant Biotechnology Journal, 5(4), 495–510. http://doi.org/10.1111/j.1467-7652.2007.00259.x, which has been published in final form at http://doi.org/10.1111/j.1467-7652.2007.00259.x. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving http://olabout.wiley.com/WileyCDA/Section/id-820227.html#terms.
autoimmune therapy, diabetes, edible crop, oral tolerance, plant-made pharmaceuticals
Ruhlman, T., Ahangari, R., Devine, A., Samsam, M., & Daniell, H. (2007). Expression of Cholera Toxin B–Proinsulin Fusion Protein in Lettuce and Tobacco Chloroplasts – Oral Administration Protects Against Development of Insulitis in Non-Obese Diabetic Mice. Plant Biotechnology Journal, 5 (4), 495-510. http://dx.doi.org/10.1111/j.1467-7652.2007.00259.x
Date Posted: 01 March 2022
This document has been peer reviewed.