Induction of IL-8 expression by Cordyceps militaris grown on germinated soybeans through lipid rafts formation and signaling pathways via ERK and JNK in A549 cells.
OBJECTIVE
In order to elucidate immunoregulatory mechanisms of Cordyceps militaris, a methanol extract of Cordyceps militaris grown on germinated soybeans was prepared and its immunoregulatory effect in the human lung epithelial cells was investigated by examining its ability to induce IL-8 expression.


METHODS
Cordyceps militaris grown on germinated soybeans was extracted with 80% methanol (GSC4M) and used for stimulation of a human lung epithelial cell-line, A549. An enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction were performed to examine the production of IL-8 protein and its mRNA, respectively. For the analysis of transcription factors regulating IL-8 transcriptional activation, the nuclear fraction was extracted from GSC4M-treated A549 cells and subjected to electrophoretic mobility shift assay.


RESULTS
GSC4M induced IL-8 protein secretion and its mRNA expression from A549 cells in a dose- and time-dependent manner. GSC4M-induced IL-8 expression was inhibited by an inhibitor for lipid rafts formation but not by that for clathrin-coated pits. In addition, signaling pathways for GSC4M-induced IL-8 expression were mediated through ERK and JNK but hardly through p38 kinase. Furthermore, GSC4M augmented the DNA-binding activity of the transcription factors AP-1, NF-IL6, and NF-kappaB, all of which are involved in the transcriptional activation of the IL-8 gene.


CONCLUSIONS
Cordyceps militaris grown on germinated soybeans stimulates lung epithelial cells to produce IL-8 through lipid rafts formation and signaling pathways via ERK and JNK.
Department of Oral Microbiology & Immunology, Dental Research Institute, and BK21 Program, School of Dentistry, Seoul National University, Seoul 110-749, Republic of Korea.
Ji Young
JY
Han
Jintaek
J
Im
Jung Nam
JN
Choi
Choong Hwan
CH
Lee
Hye Jin
HJ
Park
Dong Ki
DK
Park
Cheol-Heui
CH
Yun
Seung Hyun
SH
Han
D000276:Adjuvants, Immunologic / Q000037:antagonists & inhibitors / Q000737:chemistry; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism; D045744:Cell Line, Tumor; D032661:Cordyceps / Q000254:growth & development / Q000276:immunology*; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D018928:Immunity, Mucosal; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D021962:Membrane Microdomains / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D012137:Respiratory System / Q000378:metabolism; D015398:Signal Transduction; D013025:Glycine max / Q000382:microbiology; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000378:metabolism; D015854:Up-Regulation
D000276:Adjuvants, Immunologic; D022782:CCAAT-Enhancer-Binding Protein-beta; D016209:Interleukin-8; D016328:NF-kappa B; D018808:Transcription Factor AP-1; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases