Therapeutic effect of anti-tumor necrosis factor-alpha antibody on the murine model of viral myocarditis induced by encephalomyocarditis virus.
BACKGROUND
Tumor necrosis factor-alpha (TNF-alpha) has been reported to have an antiviral effect in vitro; however, its in vivo effect remains to be clarified.


RESULTS
To investigate the role of TNF-alpha in viral myocarditis using a murine model induced by encephalomyocarditis virus (EMCV), we evaluated (1) plasma TNF-alpha levels by enzyme-linked immunosorbent assay (ELISA), (2) the effect of recombinant human TNF-alpha for its possible antiviral effect in vivo, and (3) the effect of anti-murine TNF-alpha monoclonal antibody (mAb) in vivo. Four-week-old DBA/2 mice were inoculated intraperitoneally with EMCV (day 0). Mice were injected intravenously daily with 1 microgram of TNF-alpha or 2 x 10(3) units of anti-TNF-alpha mAb starting on day -1, day 0, or day 1 until day 2 (TNF-alpha study) or day 4 (anti-TNF-alpha mAb study). A portion of the mice were killed on day 5 (protocol 1); their hearts were removed, and plaque assays were performed to demonstrate the myocardial virus content. The remaining mice were killed on day 14 (protocol 2); myocardial lesions were examined histopathologically in terms of severity, and their survival rates were determined. Plasma TNF-alpha concentration was elevated in the blood of infected mice compared with uninfected mice 3, 5, and 7 days after virus inoculation. The myocardial virus content was higher in the TNF-alpha-treated group than in the control group. Histopathological analysis revealed that myocardial necrosis and cellular infiltration were more prominent in the TNF-alpha group than in the control group. The anti-TNF-alpha mAb improved survival and myocardial lesions when its treatment was started 1 day before virus inoculation. However, it showed no therapeutic effect when administered simultaneously with the inoculation or on day 1.


CONCLUSIONS
TNF-alpha may play an important role in the very early stage of the immune response, and anti-TNF-alpha mAb may prevent the early pathway of acute viral myocarditis.
Yamada
T
T
Department of Internal Medicine, Faculty of Medicine, Kyoto University, Japan.
Matsumori
A
A
Sasayama
S
S
D000818:Animals; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D018188:Cardiovirus Infections; D004686:Encephalomyocarditis virus; D051379:Mice; D008811:Mice, Inbred DBA; D009205:Myocarditis / Q000382:microbiology* / Q000401:mortality / Q000628:therapy*; D009206:Myocardium / Q000473:pathology; D016019:Survival Analysis; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis / Q000276:immunology* / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D014409:Tumor Necrosis Factor-alpha