Immunomodulatory activity of <i>Ganoderma lucidum</i> immunomodulatory protein <i>via</i> PI3K/Akt and MAPK signaling pathways in RAW264.7 cells

Abstract

Ganoderma lucidum immunomodulatory protein (FIP-glu) is an active ingredient with potential immunoregulatory functions. The study was conducted to explore the immunomodulatory activities of recombinant FIP-glu (rFIP-glu) and its possible mechanism in macrophage RAW264.7 cells. In vitro assays of biological activity indicated that rFIP-glu significantly activated RAW264.7 cells and possessed proinflammatory and anti-inflammatory abilities. RNA sequencing analysis and Western blot analysis showed that macrophage activation involved PI3K/Akt and MAPK pathways. Furthermore, real-time quantitative polymerase chain reaction indicated that the PI3K inhibitor LY294002 blocked the messenger RNA (mRNA) levels of MCP-1 (CCL-2), the MEK1/2 inhibitor U0126 reduced the mRNA levels of TNF-α and MCP-1 (CCL-2), and the JNK1/2/3 inhibitor SP600125 prevented the upregulation of inducible nitric oxide synthase mRNA in rFIP-glu-induced cells. rFIP-glu did not mediate these inflammatory effects through a general pathway but rather through a different pathway for a different inflammatory mediator. These data imply that rFIP-glu possessed immunomodulatory activity in macrophages, which was mediated through PI3K/Akt and MAPK pathways.