Effect of Ganoderma lucidum on inhibition of Treg cell function in mouse tumor microenvironment

Abstract:

To investigate the possible mechanism of Ganoderma lucidum inhibiting tumor，the H22 tumorbearing mice were treated with triterpenoids, polysaccharides and their mixture separately. The tumor weight and volume were measured, and the proportion of Treg cells in tumor tissues was detected by flow cytometry. The expression level of CCL22、CCR4 and FOXP3 were detected by RT-PCR. Immunohistochemical staining was used to detect the expression level of FOXP3 protein, ELISA was used to detect the cytokine content of IL-10, TGF-β1 and IL-2. The results showed the tumor inhibition rate in the mixture group(47.8%) was significantly higher than that in the triterpenoid group (21.4%) and the polysaccharide group (30.8%) . The proportion of Treg cells of the mixture group (1.93%) in the tumor microenvironment was significantly lower than that in the triterpenoid group (3.04%) and polysaccharide group (2.18%). The levels of FOXP3, IL-10, TGF-β1 and related mRNA were significantly reduced in Ganoderma lucidum groups. Meanwhile, the IL2 level was increased in Ganoderma lucidum groups. Therefore, Ganoderma lucidum can inhibit Treg cell function by reducing the infiltration of Treg cells into tumor tissue and inhibiting cytokine secretion in the mouse tumor microenvironment. Meanwhile, Ganoderma lucidum can increase the level of IL-2 in the tumor microenvironment to promote an antitumor immune response. Besides, the combination of triterpenoids and polysaccharides may have a synergistic effect.