Effects of Inonotus hispidus Extracts and Compounds on Human Immunocompetent Cells

Inonotus hispidus is used as a traditional medicine in China. Previous investigations revealed promising immunomodulatory activity of fruit body extracts of I. hispidus. Bioactivity-guided fractionation showed that hispolon and hispidin were active substances.In this study, we analysed the effects of I. hispidus extract and selected constituents on different types of human immune cells and investigated the potential of I. hispidus extract as a medicinal mushroom. The influence of I. hispidus extract on activity and maturation of human T cells, purified natural killer cells, and dendritic cells was analysed using cytometric-based surface marker expression. The cell division characteristics of the activated T cells were assessed by membrane permeable dye, and the function of natural killer cells was investigated by a degranulation CD107a assay. Apoptosis induction was assessed by surface staining of phosphatidylserine, and camptothecin and cyclosporine A were used individually as controls. Phytochemical analysis, using TLC chromatograms and HPLC analysis, was conducted to characterise the I. hispidus extract. I. hispidus extract increased the activation and diminished the proliferation of activated human T cells in the presence of apoptosis. Natural killer cell activity and function were dose-dependently increased. Surface marker expression of dendritic cells demonstrated that I. hispidus extract has the potential to induce maturation. TLC and HPLC analyses showed that the extract contained hispidin and hispolon. Investigations using hispidin and hispolon demonstrated similar, albeit noncongruent, results with extracts on measured parameters.The results indicate that extracts from I. hispidus and their constituents, hispidin and hispolon, interfere with the function of multiple immune cells, thus providing a rationale for their potential as a medicinal mushroom.