Dual Effect of the Extract from the Fungus Coriolus versicolor on Lipopolysaccharide-Induced Cytokine Production in RAW 264.7 Macrophages Depending on the Lipopolysaccharide Concentration

Purpose: Extract from the fungus Coriolus versicolor (CV) is classified as an immunological response modifier. Previously, we have shown that this extract induces interleukin 6 (IL-6)-related extension of lipopolysaccharide (LPS)-induced fever. This study investigated the effect of CV extract on the production of pro-inflammatory cytokines and the expression of components of signal transduction pathways leading to the secretion of cytokines from RAW 264.7 macrophages stimulated with different doses of LPS. Methods: RAW 264.7 cells were stimulated with CV extract alone or co-treated with CV extract and LPS. The level of IL-6 and tumour necrosis factor alpha (TNF-alpha) in the culture media was measured using ELISA. Protein expression of Toll-like receptor (TLR) 4, phosphorylated I kappa B (p-I kappa B), CD14 glycoprotein and phospho-phosphatidylinositol 3-kinase (p-PI3K) was evaluated using Western blot. The effects of TLR4, nuclear factor kappa B (NF-kappa B) and p-PI3K on cytokine secretion were estimated using inhibitors: TAK-242, JSH-23 and LY294002. Results: CV extract itself stimulates the secretion of IL-6 and TNF-alpha and increases the expression of TLR4, p-I kappa B and p-PI3K. The presence of CV extract during the treatment of cells with lower concentrations of LPS (10 and 100 ng/mL) increases the cytokine production. Co-stimulation of cells with CV extract and LPS at a higher dose (500 ng/mL) decreases the secretion of cytokines. This effect is related to the changes in the expression of TLR4, CD14 glycoprotein, p-I kappa B and p-PI3K. Conclusion: This is the first report showing that the CV extract-induced production of cytokines is mediated by the PI3K signalling pathway. This extract acts antagonistically or additively with LPS on the production of IL-6 and TNF-alpha, depending on the LPS concentration. Our results are helpful for illustrating the mechanisms for the immunostimulatory effect of CV extract in inflammatory processes.

Automated summary

This study investigated the effects of extract from Coriolus versicolor on the production of pro-inflammatory cytokines in macrophages. The results showed that the extract can stimulate the secretion of IL-6 and TNF-α, and alter the expression of related signaling pathway components. The effects of the extract on cytokine production can be antagonistic or additive depending on the concentration of LPS.