Ganoderma lucidum is a popular medicinal mushroom, which has been used in the Traditional Chinese medicine for the prevention or treatment of a variety of diseases. In the present study we evaluated the anti-inflammatory effects of the triterpene extract from G. lucidum(GLT) in LPS-stimulated macrophages. Here we show that GLT markedly suppressed the secretion of inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6), and inflammatory mediator nitric oxide (NO) and prostaglandin E(2) (PGE(2)) from lipopolysaccharide (LPS)-stimulated murine RAW264.7 cells. GLT also down-regulated LPS-dependent expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) in RAW264.7 cells. The anti-inflammatory effects of GLT were mediated by the inhibition of transcription factor NF-kappaB as demonstrated by decreased NF-kappaB-DNA binding activity, and the suppression of p65 phosphorylation in LPS-stimulated macrophages treated with GLT. Moreover, GLT inhibited LPS-dependent AP-1-DNA binding activity and down-regulated expression of AP-1 subunit c-Jun. In addition, GLT suppressed the activity of MAP kinases as observed by the down-regulation of LPS-induced phosphorylation of ERK1/2 and JNK but not p38. In vivo experiments clearly demonstrated that GLT also inhibited the production of TNF-alpha and IL-6 in LPS-induced endotoxemic mice. Apart from its anti-inflammatory activity, GLT suppressed cell proliferation of RAW264.7 cells through cell cycle arrest at G0/G1-G2M, which was mediated by the down-regulation of expression of cell cycle regulatory proteins cyclin D1, CDK4 and cyclin B1, respectively. In conclusion, the anti-inflammatory and anti-proliferative effects of GLT on macrophages are mediated through the inhibition of NF-kappaB and AP-1 signaling pathways.

BACKGROUND: Crohn's disease (CD) is a chronic inflammatory disease of the gastrointestinal tract. Current medications have potentially serious side effects. Hence, there is increasing interest in alternative therapies. We previously demonstrated the anti-inflammatory effects of Food Allergy Herbal Formula-2 in vitro on peripheral blood mononuclear cells (PBMCs) and mucosa from CD subjects. Here, we investigated the anti-inflammatory effects of a bioactive compound isolated from Ganoderma lucidum (G. lucidum), a key herbal constituent of Food Allergy Herbal Formula-2, in CD in vitro.

METHODS: Triterpene ganoderic acid C1 (GAC1) was isolated from G. lucidum. Stimulated RAW 264.7 macrophages were treated with GAC1. Human PBMCs and colonic biopsies were obtained from children with CD and cultured with or without GAC1. TNF-α and other proinflammatory cytokine levels were measured in the culture supernatant. NF-κB signaling was investigated in PBMCs and colonic mucosa treated with GAC1 by In-Cell Western and Western blot analysis.

RESULTS: GAC1 decreased TNF-α production by macrophages and PBMCs from CD subjects. GAC1 significantly decreased TNF-α, IFN-γ, and IL-17A production by inflamed colonic biopsies from CD subjects. These effects were due to downregulation of the NF-κB signaling pathway.

CONCLUSIONS: GAC1 inhibited production of TNF-α and other proinflammatory cytokines by PBMCs and inflamed CD colonic mucosa due to blockage of NF-κB activation. GAC1 is a key beneficial constituent in G. lucidum and the Food Allergy Herbal Formula-2 in suppressing the inflammatory cytokines found in CD and warrants clinical investigation for the treatment of CD.