Polysaccharides derived from Ganoderma lucidum fungus mycelia ameliorate indomethacin-induced small intestinal injury via induction of GM-CSF from macrophages

Non-steroidal anti-inflammatory drugs often cause ulcers in the human small intestine, but few effective agents exist to treat such injury. Ganoderma lucidum Karst, also known as “Reishi” or “Lingzhi”, is a mushroom. We previously reported that a water-soluble extract from G. lucidum fungus mycelia (MAK) has anti-inflammatory effects in murine colitis induced by trinitrobenzene sulfonic acid, and induction of granulocyte macrophage colony-stimulating factor (GM-CSF) by MAK may provide anti-inflammatory effects. However, its effects on indomethacin-induced small intestinal injuries are unknown. The present study investigated the preventative effects of MAK via immunological function and the polysaccharides from MAK on indomethacin-induced ileitis in mice. Peritoneal macrophages (PMs) were stimulated in vitro with MAK and adoptively transferred to C57BL/6 mice intraperitoneally, which were then given indomethacin. Intestinal inflammation was evaluated after 24 h. We performed in vivo antibody blockade to investigate the preventive role of GM-CSF, which derived from PMs stimulated with MAK. We then used PMs stimulated with MAK pre-treated by pectinase in an adoptive transfer assay to determine the preventive role of polysaccharides. Indomethacin-induced small intestinal injury was inhibited by adoptive transfer of PMs stimulated in vitro with MAK. In this transfer model, pre-treatment with anti-GM-CSF antibody but not with control antibody reversed the improvement of small intestinal inflammation by indomethacin. Pectinase pretreatment impaired the anti-inflammatory effect of MAK. PMs stimulated by MAK appear to contribute to the anti-inflammatory response through GM-CSF in small intestinal injury induced by indomethacin. The polysaccharides may be the components that elicit the anti-inflammatory effect.