Authors

T. Ruhlman; R. Ahangari; A. Devine; M. Samsam;H. Daniell

Comments

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Abbreviated Journal Title

Plant Biotechnol. J.

Keywords

autoimmune therapy; diabetes; edible crop; oral tolerance; plant-made; pharmaceuticals; BETA-CELL FUNCTION; LACTUCA-SATIVA L.; TRANSGENIC CHLOROPLASTS; T-CELLS; STABLE TRANSFORMATION; VACCINE ANTIGENS; TOLERANCE; SUBUNIT; GENE; INDUCTION; Biotechnology & Applied Microbiology; Plant Sciences

Abstract

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 similar to 16% of total soluble protein (TSP) in tobacco and up to similar 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 beta-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 beta-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 beta-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 T-1 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.

Journal Title

Plant Biotechnology Journal

Volume

5

Issue/Number

4

Publication Date

1-1-2007

Document Type

Article

Language

English

First Page

495

Last Page

510

WOS Identifier

WOS:000247174600005

ISSN

1467-7644

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