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International Journal of Medicinal Mushrooms
IF: 1.423 5-Year IF: 1.525 SJR: 0.433 SNIP: 0.661 CiteScore™: 1.38

ISSN Print: 1521-9437
ISSN Online: 1940-4344

International Journal of Medicinal Mushrooms

DOI: 10.1615/IntJMedMushr.v8.i3.40
pages 223-229

An Immunomodulating Polysaccharide in Agaricus brasiliensis S. Wasser et al. (Agaricomycetideae) Activates Macrophages through Toll-like Receptor 4

Masashi Mizuno
Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe, Japan
Sachiko Kawakami
Graduate School of Science and Technology, Kobe University, Kobe, Japan

ABSTRACT

Peritoneal macrophages from toll-like receptor (TLR) 4 and TLR2 knockout mice (TLR4−/− and TLR2−/−) were stimulated with a water-insoluble hetero-glycan (ABHG), purified from a fruit body of Agaricus brasiliensis. TLR4−/− mice did not produce tumor necrosis factor (TNF)−α and nitric oxide (NO), but TLR2−/− did. However, ABHG did not inhibit TNF-α and NO production by macrophages in the presence of polymyxin B, which could bind to lipid A in lipopolysaccharide (LPS); suggesting that ABHG did not contain LPS as contaminants. These results indicated that ABHG was recognized through TLR4−/− to produce inflammatory cytokines such as TNF-α and NO. RT-PCR was used to investigate the effect of ABHG on mRNA expression of TNF-α and inducible nitric oxide synthase (iNOS) in RAW 264.7. TNF-α mRNA expression was induced 0.5 hr after stimulation, peaked in 3 hr, and thereafter decreased to reach a stable level after 24 hr. On the other hand, iNOS mRNA induction was delayed for 3 hr and thereafter remained at the same level until 24 hr after stimulation. Furthermore, the DNA binding activity of NF-κB was observed as early as 0.5 hr after treatment and rapidly increased to its peak value 2 hr later, and thereafter decreased. When RAW 264.7 was stimulated with ABHG in the presence of an anti-TNF-α antibody, TNF-α mRNA expression was not affected and iNOS was downregulated. These results indicate that TNF-α production by RAW 264.7, stimulated with an immunomodulating polysaccharide such as ABHG, was enhanced by upregulating of NF-κB through TLR4, and the newly produced TNF-α enhanced NO production trough an autocrine pathway.


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