Phellinus linteus polysaccharides and their immunomodulatory properties in human monocytic cells

Phellinus linteus (PL), a high value medicinal mushroom, is popularly consumed as traditional medicine and health foods for enhancing immune functions in Asia. This study aimed to examine the immunomodulating properties of aqueous (HPL) and ethanol (EPL) extracts, and polysaccharides (PSCPL) of cultured P. linteus fruiting bodies in lipopolysaccharide (LPS)-induced human monocytic (THP-1) cells, as well as investigating the chemical properties of PSCPL. Results showed that at concentrations <10 mu g/mL, PSCPL with molecular weight ranging from 22 to 1700 kDa was more effective than HPL and EPL in protecting against LPS-induced cell toxicity. At 5 mu g/mL, PSCPL significantly blocked myeloid differentiation factor 88 (MyD88), tumour necrosis factor receptor-associated factor-6 (TRAF-6), vascular cell adhesion molecule-1 (VCAM-1) and nuclear factor-kappa B (NF-kappa B) expression, as well as inhibiting reactive oxygen species (ROS) formation and cytokine (TNF-alpha, IL-1 alpha, IL-1 beta and IL-4) production in LPS-stimulated cells. It also effectively suppressed the activation and phosphorylation of c-Jun N-terminal kinase (JNK) and p38. Taken together, PSCPL shows a stronger immunomodulatory activity than HPL and EPL, and this activity could be mediated through the MyD88-dependent and mitogen-activated protein kinase (MAPK) signaling pathways. (C) 2013 Elsevier Ltd. All rights reserved.