Abrogation of streptococcal pyrogenic exotoxin B-mediated suppression of phagocytosis in U937 cells by Cordyceps sinensis mycelium via production of cytokines

Chih Feng Kuo, Cheng Chih Chen, Chiou Feng Lin, Ming Shiou Jan, Robert Y. Huang, Yueh Hsia Luo, Woei Jer Chuang, Chia Chin Sheu, Yee Shin Lin

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Streptococcal pyrogenic exotoxin B (SPE B) is a virulent factor in group A streptococcal infection. We previously showed that SPE B reduced phagocytosis in human monocytic U937 cells. Here we show that the mycelium extract of Cordyceps sinensis (CS), a Chinese immunomodulatory herbal medicine, increased phagocytosis in U937 cells. Neither heat nor trypsin pretreatment prevented CS extract from causing this increase. Further studies indicated that SPE B-mediated suppression of U937 cell phagocytic activity was abrogated by CS extract. Factors in the conditioned medium from CS-extract-treated U937 cells were responsible for blocking the SPE B-mediated suppression of phagocytosis. Heating the conditioned medium eliminated the increase, which suggested that the U937-cell protein products augmented phagocytosis. Analyzing cytokine mRNA expression of U937 cells revealed increases in interferon-γ (IFN-γ), interleukin (IL)-12 p35 and p40, and tumor necrosis factor-α (TNF-α), but not in IL-1β, IL-6, or IL-8. Treating U937 cells with anti-IFN-γ, IL-12, and TNF-α antibodies also eliminated the conditioned medium-induced increase in phagocytosis. Taken together, SPE B inhibited phagocytosis, but CS mycelium extract abrogated this inhibition by causing cytokine production.

Original languageEnglish
Pages (from-to)278-285
Number of pages8
JournalFood and Chemical Toxicology
Volume45
Issue number2
DOIs
Publication statusPublished - Feb 2007
Externally publishedYes

Keywords

  • Cordyceps sinensis mycelium
  • Cytokines
  • Phagocytosis
  • Streptococcal pyrogenic exotoxin B

ASJC Scopus subject areas

  • Food Science
  • Toxicology

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