A targeted DNA vaccine encoding Fas ligand defines its dual role in the regulation of experimental autoimmune encephalomyelitis
Gizi Wildbaum, … , Gila Maor, Nathan Karin
Gizi Wildbaum, … , Gila Maor, Nathan Karin
Published September 1, 2000
Citation Information: J Clin Invest. 2000;106(5):671-679. https://doi.org/10.1172/JCI8759.
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Article

A targeted DNA vaccine encoding Fas ligand defines its dual role in the regulation of experimental autoimmune encephalomyelitis

Abstract

This study used naked DNA vaccination to induce breakdown of tolerance to self and thus elicit immunological memory to native, membrane-bound Fas ligand (FasL). Upon induction of experimental autoimmune encephalomyelitis (EAE), this memory was turned on to provide protective immunity. FasL-specific autoantibodies isolated from protected animals differentially downregulated the in vitro production of TNF-α, but not IFN-γ, by cultured T cells. These autoantibodies were highly protective when they were administered to rats at the onset of EAE. In contrast, administration of these FasL-specific Ab’s to EAE rats after the peak of the acute phase of disease prevented spontaneous recovery from disease. This extended illness is partially explained by inhibition of mononuclear cell apoptosis at the target organ, which resulted in increased accumulation of T cells and macrophages at the site of inflammation. Hence, FasL exerts two distinct, stage-specific regulatory functions in the control of this T-cell mediated autoimmune disease of the central nervous system.

Authors

Gizi Wildbaum, Juergen Westermann, Gila Maor, Nathan Karin

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FasL-specific Ab’s generated in DNA-vaccinated rats bind native FasL. Le...
FasL-specific Ab’s generated in DNA-vaccinated rats bind native FasL. Lewis rats were subjected to four weekly injections of the FasL DNA construct as described in Figure 1. Two months after the last immunization, when FasL-specific Ab titer retained a base line, these rats, as well as rats treated with either the pcDNA3 alone or PBS, were injected with p68-86/CFA to induce active EAE and were sacrificed at different time points. Blood serum and SCF from these rats were analyzed for the presence of Ab’s to FasL. (a) Log2 Ab titers determined at the onset of disease (day 13). Results are shown as mean of three samples from different rats ± SE. (b) Plasma membrane proteins were obtained from nonactivated (lane c) or 24-hour–activated (lanes a, b, and d) splenic T cells. SDS-PAGE under reducing conditions was used to separate membrane proteins that were then subjected to Western blot analysis using either a commercially available (see Methods) FasL-specific Ab (lane a), our purified Ab’s obtained by naked DNA vaccination (lanes b and c), or control IgG from normal rat serum (lane d). (c and d) Binding of self-specific anti-FasL obtained by naked DNA vaccination to their target receptor (membrane-bound FasL) was determined by flow-cytometry analysis on activated MBP-specific T cells (c) and thioglycollate-elicited peritoneal macrophages (d).