Enhancement of IL-18 expression by Paecilomyces tenuipes

Paecilomyces tenuipes is a popular medicinal mushroom, and has received extensive attention for medical application because of its various physiological activities. However, there is limited information about the anticancer and immunomodulatory activities of Paecilomyces tenuipes. This study attempted to evaluate the effect of an extract from the cultured fruiting bodies of Paecilomyces tenuipes (PTE) on the expression of the interleukin- 18 (IL-18) gene in rat pheochromocytoma (PC) 12 cells and rat brain. Related mRNA levels were determined by reverse transcription-polymerase chain reaction (RT-PCR). Protein levels were measured by Western blot and immunohistochemistry. Our results demonstrated that PTE induced IL-18 gene expression both in vitro and in vivo. Treatment of PC12 cells and rat brain cells with 10 μg/ml and 20 mg/kg PTE, respectively, yielded significant increases of IL-18 levels. Significantly, IL-18-immunoreactive neurons were detected in the Purkinje cells of the cerebellum. IL18-immunohistochemical staining was markedly enhanced in animals treated with PTE compared to findings in the untreated controls. These results suggest that PTE could be a potential candidate as an immune activator or anticancer drug.