Immunomodulatory Effects of Extract of Lingzhi or Reishi Medicinal Mushroom Ganoderma lucidum (Agaricomycetes) Basidiocarps Cultivated on Alternative Substrate

Abstract

Ganoderma lucidum is a medicinal mushroom exhibiting numerous health benefits primarily based on strong immunostimulatory effects. The study aimed to investigate if there were differences in effects of extracts of commercially (GC) and alternatively (wheat straw) (GA) cultivated G. lucidum basidiocarps on properties of peritoneal macrophages (PM) and monocyte-derived dendritic cells (MoDCs). Differences in immunomodulatory effects of GC/GA extracts were studied. The viability of treated PMs, their adhesive and phagocytic capability, and their capacity to produce reactive oxygen species (ROS) and NO were tested. Immature MoDCs generated from human monocytes were treated with poly I:C (10.0 μg/ml) and loxoribine (34.0 μg/ml), a selective TLR3 and TLR7 agonists, respectively, and with/without GC/GA extract (100.0 μg/ml). The effect of each combination on phenotypic properties, cytokines production by MoDCs, and their proliferation and Th polarizing capacity was studied. GA extract stimulated the metabolic and phagocytic activity of PMs, their adhesion capability, and ability to produce ROS and NO more strongly compared to GC. Both tested extracts significantly increased allostimulatory and Th1 polarization capacity of simultaneous TLR3 and TLR7-activated MoDCs, but GA extract was more effective. The extract of alternatively cultivated G. lucidum basidiocarps increased production of ROS and NO by TLR4 stimulated PMs and upregulated production of certain cytokines as well as allostimulatory and Th1 polarization capacity of MoDCs. GA extract could be a potent immunostimulatory agent for activation of MoDCs with the simultaneous engagement of TLRs, which seems to be a promising strategy for the preparation of DC-based anti-tumor vaccines.