TLR4-mediated activation of macrophages by the polysaccharide fraction from Polyporus umbellatus(pers.) Fries

J Ethnopharmacol. 2011 Apr 26;135(1):1-6. doi: 10.1016/j.jep.2010.06.028. Epub 2010 Jul 1.


Aim of the study: Zhu Ling (Polyporus umbellatus) is well-known to reduce the risk of a variety of diseases. In this study, we explored the molecular mechanism of its immunostimulatory potency in immune responses of macrophages, using polysaccharides prepared from Polyporus umbellatus (PPS).

Materials and methods: Splenocyte proliferation was analyzed with (3)H-TdR incorporation method. Nitric oxide (NO) was measured by Griess method and cytokines of culture supernatants was detected by enzyme linked immunosorbent assay (ELISA). The fluoresceinamine-labeled PPS (Flu-PPS) and dextran (Flu-dextran) were prepared by the cyanogen bromide activation method. The cell-binding activity of Flu-PPS was analyzed with FACS and confocal microscopy. NF-κB activity was measured by ELISA assay.

Results: We found that PPS is able to strongly upregulate the functions of macrophages such as Nitric oxide (NO) production and cytokine expression. Compared with C3H/HeJ group, PPS significantly stimulated the proliferation of splenocytes and the production of TNF-α, IL-1β and NO of peritoneal macrophages from C3H/HeN mice. The function blocking antibodies to TLR-4, but not TLR-2 and CR3, markedly suppressed PPS-mediated TNF-α and IL-1β production. Flow cytometric and confocal laser-scanning microscopy analysis shown that fluorescence-labeled PPS (f-PPS) can bind specifically to the target cells, and the binding can blocked by unlabeled PPS and anti-TLR4, but not anti-TLR2 and CR3 monoclonal antibodies. Nuclear translocation and DNA binding activity of NF-κB was significantly induced by PPS.

Conclusions: Therefore, our data suggest that PPS may exert its immunostimulating potency via TLR-4 activation of signaling pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Monoclonal / metabolism
  • Biological Transport / drug effects
  • Cell Nucleus / metabolism
  • Cytokines / metabolism
  • Drugs, Chinese Herbal / pharmacology*
  • Female
  • Inflammation Mediators / metabolism*
  • Macrophages, Peritoneal / drug effects*
  • Macrophages, Peritoneal / metabolism
  • Mice
  • Mice, Inbred C3H
  • NF-kappa B / metabolism
  • Nitric Oxide / biosynthesis
  • Polyporus / chemistry*
  • Polysaccharides / pharmacology*
  • Spleen / cytology
  • Spleen / drug effects*
  • Toll-Like Receptor 4 / immunology*
  • Up-Regulation


  • Antibodies, Monoclonal
  • Cytokines
  • Drugs, Chinese Herbal
  • Inflammation Mediators
  • NF-kappa B
  • Polysaccharides
  • Toll-Like Receptor 4
  • Nitric Oxide