Ganoderma lucidum polysaccharides promote T lymphocyte infiltration into tumor by regulating expression of ICAM-1 in endothelial cells

Abstract

Polysaccharide is among the main active components of Ganoderma lucidum for tumor prevention and treatment. Howe-ver, it remains unclear whether it has synergy with tumor immunotherapy. This study evaluated the effect of G. lucidum polysaccharides(GLP) on the infiltration of T lymphocytes into tumor and the underlying mechanism, in order to provide a reference for its application in tumor immunotherapy. GLP were prepared by water extraction and alcohol precipitation combined with Sevag method and then given(intraperitoneal injection) to the mice bearing B16-F10 cells at 25, 50 and 100 mg kg~(-1), respectively, to evaluate the effect on tumor growth. The infiltration of CD3~+ and CD8~+ T cells and the expression of intercellular cell adhesion molecule-1(ICAM-1) in tumor were detected by immunohistochemistry. EA.hy926 cells were treated with 50, 100 and 200 μg·mL~(-1) GLP, and the expression of ICAM-1 was determined by Western blot. The adhesion of EA.hy926 cells treated with GLP was measured with fluorescence-labeled Jurkat cells. To analyze the mechanism based on NF-κB pathway, this study determined the protein levels of nuclear factor kappa-B(NF-κB) p65, alpha inhibitor of NF-κB(IκBα), p-NF-κB p65 and p-IκBα by Western blot. The results showed that GLP can significantly inhibit the tumor growth in mice bearing B16-F10 cells, promote the infiltration of CD3~+ and CD8~+ T cells in tumor, and increase the expression of ICAM-1 in tumor. Meanwhile, GLP could also enhance the expression of ICAM-1 in EA.hy926 cells, thus strengthen the adhesion to Jurkat cells, induce phosphorylation and protein degradation of IκBα, and raise the expression and phosphorylation level of NF-κB p65. These results suggested that GLP could promote the expression of ICAM-1 through NF-κB pathway and further enhance the infiltration of T lymphocytes into tumor, thereby inhibiting tumor growth. This study lays a foundation for the further application of GLP in tumor immunotherapy.