Cytokine gene therapy for myocarditis by in vivo electroporation

Cytokines are important pathophysiologic and pathogenic factors in cardiova scular disorders, including viral myocarditis. We attempted to treat viral myocarditis with cytokine gene therapy by transferring an inhibitory cytoki ne, IL-1 receptor antagonist (IL-1ra) or viral IL-10 (vIL-10), by in vivo e lectroporation, a new method for gene transfer into muscle. Four-week-old m ale DBA/2 mice were inoculated intraperitoneally with 10 PFU of encephalomy ocarditis virus. Immediately after virus inoculation, an expression plasmid carrying IL-1ra or vIL-10 was injected into tibialis anterior muscles foll owed by electroporation. Serum levels of IL-1ra and vIL-10 reached 10.5 and 2.3 ng/ml, respectively, on day 5, when gene expression reached its peak. Histopathological examination showed that myocardial cellular infiltration was improved in mice treated with IL-1ra or vIL-10 compared with the contro l group. On day 14 after the onset of myocarditis, transfer of IL-1ra or vI L-10 expression plasmid had significantly improved the survival rates of th e animals. The expression of TNF-alpha was decreased to 0.60-fold (p< 0.005 ) and inducible nitric oxide synthase (iNOS) 0.43-fold (p< 0.005) by IL-1ra treatment, and the expression of IFN-gamma in the heart was decreased to 0 .35-fold (p< 0.05), and iNOS 0.21-fold (p< 0.005), by vIL-10 relative to th e controls. These results show that gene therapy with IL-1ra or vIL-10 expr ession plasmid was effective in the treatment of viral myocarditis, and in vivo electroporation may be a useful method by which to deliver cytokine th erapy in cardiovascular diseases.