GSP-2, a polysaccharide extracted from Ganoderma sinense, is a novel toll-like receptor 4 agonist

Kai Sheng Liu, Cheng Zhang, Hong Liang Dong, Kai Kai Li, Simon Q B HAN, Yong Wan, Rui Chen, Fang Yang, Hai Li Li, Chun Hay Ko*, Xiao Qiang Han

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Ganoderma sinense is a Chinese unique medicinal fungus that has been used in folk medicine for thousands of years. Polysaccharides are considered to be biologically active ingredients due to their immune-modulating functions. Previously we found that GSP-2, a new polysaccharide isolated from Ganoderma sinense, exerts an immunomodulatory effect in human peripheral blood mononuclear cells but the underlying mechanism is unclear. The present study aimed to investigate how GSP-2 triggers immunologic responses and the implicated signaling pathways. GSP-2 effects were investigated both in a macrophagic cell line, RAW264.7, and in primary macrophages. Moreover, the molecular basis of GSP-2 recognition by immune cells, and the consequent activation of signaling cascades, were explored by employing recombinant human HEK293-TLR-Blue clones, individually overexpressing various Toll-like receptors. GSP-2 dose-dependently induced the overexpression of Toll-like receptor 4 (TLR4) but did not affect the expression of other TLRs. Moreover, GSP-2 induced TNFα secretion in primary macrophages from wild-type, but not TLR4- knockout mice. In addition, GSP-2 upregulated TLR4 protein expression and activated the MAPK pathway in RAW246.7 macrophages. Finally, GSP-2 induced the production of the cytokines TNFα, IL1β, and IL6. Our data demonstrated that GSP-2 was specifically recognized by TLR4, promoting cytokine secretion and immune modulation in macrophages.

Original languageEnglish
Article numbere0221636
JournalPLoS ONE
Volume14
Issue number8
DOIs
Publication statusPublished - 1 Aug 2019

Scopus Subject Areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • General

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