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

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-gamma (IFN-gamma), interleukin (IL)-12 p35 and p40, and tumor necrosis factor-alpha (TNF-alpha), but not in IL-1beta, IL-6, or IL-8. Treating U937 cells with anti-IFN-gamma, IL-12, and TNF-alpha 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.

• Authors: 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
• Journal: Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association (Food Chem Toxicol) Vol. 45 Issue 2 Pg. 278-85 (Feb 2007) ISSN: 0278-6915 [Print] England
• PMID: 17029726 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Bacterial Proteins
• Cytokines
• Exotoxins
• Immunosuppressive Agents
• erythrogenic toxin
• Trypsin

Topics

• Bacterial Proteins (antagonists & inhibitors, toxicity)
• Cordyceps (chemistry, immunology, metabolism)
• Cytokines (biosynthesis, immunology, pharmacology)
• Exotoxins (antagonists & inhibitors, toxicity)
• Fluorescence
• Hot Temperature
• Humans
• Immunosuppressive Agents (pharmacology)
• Mycelium (chemistry, immunology, metabolism)
• Phagocytosis (drug effects)
• Streptococcus pyogenes (metabolism)
• Trypsin (pharmacology)
• U937 Cells