- Paper Report
- Open Access
Treatment of murine lupus with cDNA encoding IFN-?R/Fc
- Cheryl Smythe1
© Current Science Ltd 2000
- Published: 12 September 2000
- lupus,Fc fusion protein
- plasmid gene therapy
Increased levels of IFN-? have been observed in both lupus-prone mice and humans and are thought to be central to disease progression: lupus-prone mice treated with IFN-? exhibit accelerated disease, whereas those treated with an anti-IFN-? antibody have a delayed disease onset. Furthermore, deletion of either the IFN-? or IFN-? receptor (IFN-?R) genes in lupus-prone mice significantly decreases the humoral and histological characteristics of the disease. The present study describes a novel therapeutic intervention whereby the disease-promoting effects of IFN-? are blocked by the expression of an IFN-?R/IgG1Fc fusion protein. To evaluate whether intramuscular injections of a plasmid containing cDNA that encodes IFN-?R/IgG1Fc can retard lupus development and progression in lupus-prone mice.
MRL-Faslpr mice were injected with either VR1255-IFN-?R/Fc or VR1255 plasmids at monthly intervals up to 6 months of age and then bimonthly. Serum levels of IFN-?R/Fc in mice injected without electroporation were undetectable 6 weeks after two injections, whereas those injected together with electroporation exhibited a mean level of 144 ng/ml. The in vivo blocking activity of the expressed receptor was ascertained by measuring serum IFN-? levels at the time of death. Mice injected with the active plasmid without electroporation had half the level of IFN-? compared to control animals, while injection of the active plasmid plus electroporation reduced IFN-? levels to 10-25%. A survival rate of 100% was observed at 14 months where the injections plus electroporation were initiated at 4 months (diseased), while this dropped to 90% when initiated at 1 month (pre-disease). Injection of the active plasmid plus electroporation at 4 months resulted in a significant reduction in the levels of both polyclonal IgG2a and anti-chromatin autoantibody subclass IgG2a. Lymphoid hyperplasia, glomerulonephritis and blood urea nitrogen levels were reduced in treated animals and fewer infiltrating macrophages and T cells were observed within the kidneys. Decreased kidney IgG deposits together with lower expression of MHC class II, ICAM-1 and MCP-1 were also noted in the active plasmid treated mice.
The extracellular portion of mouse IFN-?R a-chain and IgG1 constant heavy-chain cDNA were generated by RT-PCR and used to generate a full-length IFN-?R/IgG1Fc cDNA segment by PCR. This fragment was then inserted into the VICAL VR1255 vector. Plasmid DNA was prepared by the alkali lysis method. Anaesthetized MRL-Faslpr mice were injected with either VR1255-IFN-?R/Fc or VR1255 plasmids into both tibialis anterior muscles. Electroporation was carried out using a pair of electrode needles, which were inserted into the muscle bed 5 mm apart on either side of the injection site. IgG subclasses and serum IFN-?R/Fc fusion protein levels were measured by ELISA. Intracellular IFN-? was measured FACs analysis of permeabilized cells and MHC class II, ICAM-1, MCP-1 F4/80 and CD3 expression in the kidneys was determined by immunocytochemical analysis.