Suppression of tissue necrosis factor-alpha or hydrogen peroxide-activated primary human T lymphocytes by Ginkgo biloba extract through down-regulation of activator protein-1 signal transduction

It was unknown whether Ginkgo biloba extract has regulatory effects on human T lymphocytes activated by tissue necrosis factor-alpha (TNF- α), which has an important role on the progression of inflammatory atherosclerotic plaques. We evaluated the effects of G. biloba extract on activated human peripheral T lymphocytes, which were isolated from human whole blood. The human T lymphocytes were treated with 25–100 μg G. biloba extract for 2 h first. Then they were activated by TNF- α and H 2O 2 to investigate the modulatory effects of G. biloba extract on human T lymphocytes. Electrophoretic mobility shift assay, Western blot (Immunoblot) analysis and immunoprecipitation kinase assays were used. The inhibition of activated human T lymphocyte specifically correlated with the down-regulation of AP-1 DNA-binding activities. G. biloba extract was unique in its ability to inhibit the activation of c-Jun NH 2-terminal protein kinase. G. biloba extract might have its novel therapeutic effects on inflammation-based atherosclerotic diseases.