French maritime pine bark extract inhibits viral replication and prevents development of viral myocarditis

BackgroundFrench maritime pine bark extract (Pycnogenol) revealed diverse anti-inflammatory actions by an inhibition of NF-κB–dependent gene expression. The aim of this study was to determine whether Pycnogenol had a beneficial effect on viral myocarditis in mice.Methods and MaterialsFour-week-old inbred male DBA/2 mice were inoculated intraperitoneally with 10 plaque-forming units (pfu) of the encephalomyocarditis (EMC) virus. Pycnogenol was administered orally at a dose of 1 or 10 mg/kg per day for the histologic study, and 10 or 100 mg/kg for the gene expression study, beginning on the day of viral inoculation.ResultsThe area of myocardial infiltration and necrosis on day 7 was significantly smaller in the hearts of mice treated with Pycnogenol 10 mg/kg (16.2 ± 8.9% and 19.2 ± 9.7%, respectively, n = 10, mean ± SEM) compared with controls (27.6 ± 15.0% and 30.1 ± 15.7%, respectively, n = 10, P < .05). There was a nonsignificant trend for less myocardial infiltration in the Pycnogenol 1 mg/kg group. Myocardial virus concentration on day 7 was 8.4 ± 0.3 × 10³ pfu/mg in mice treated with 1 mg/kg of Pycnogenol, and 2.7 ± 0.6 × 10⁴ pfu/mg in control mice, and the difference was statistically significant (P < .05). Gene expressions of tumor necrosis factor, type-I procollagen, stem cell factor, and mast cell tryptase were significantly suppressed in the hearts of mice treated with Pycnogenol 100 mg/kg.ConclusionsThese results suggest that Pycnogenol exerts its beneficial effects on viral myocarditis by decreasing virus replication, and by suppressing expression of pro-inflammatory cytokines, genes related to cardiac remodeling, and mast cell–related genes in the hearts of mice.