House dust mite extract induces interleukin-9 expression in human eosinophils.
BACKGROUND
Eosinophils play a pivotal role in allergic inflammation. Recent evidence suggests that they not only function as terminal effector cells but have potential to interact with allergen and initiate immune responses. We investigated cytokine production from eosinophils through direct interaction with a major allergen, house dust mite (HDM) .


METHODS
Purified eosinophils from HDM-sensitized or non-sensitized donors were cultured with HDM extract or lipopolysaccharide (LPS) for 18 or 40 h. A panel of cytokine gene expression in eosinophils was examined by means of real-time RT-PCR. Released cytokines in the culture supernatants were assessed with a specific ELISA. In some experiments, HDM was pretreated with protease inhibitors, then added to the culture. Cytokines tested for gene expression were interleukin (IL)-2, 4, 6, 7, 8, 9, 10, 11, 12, 13, 16,17, 18, TGF-beta1 and GM-CSF,.


RESULTS
LPS induced small enhancement of GM-CSF gene expression at 18 h. At 40 h, HDM induced about 60-fold enhancement of IL-9 gene expression. IL-9 protein was also detected in the culture supernatants at 60 h. Those reactions were observed regardless of HDM sensitization status of the donors. HDM-induced IL-9 expression was completely inhibited with a serine protease inhibitor, AEBSF, not with a cysteine protease inhibitor, E-64.


CONCLUSIONS
Accumulated eosinophils in the airways in asthma may directly react with HDM and produce IL-9 to further promote Th2-type immune responses. Protease-activated receptor 2, a ligand for serine proteases, which contained in HDM, may be involved in the reaction.
Fujisawa
Takao
T
Institute for Clinical Research, Mie National Hospital, Tsu, Mie, Japan. fujisawa@mie-m.hosp.go.jp
Katsumata
Hajime
H
Kato
Yoshiko
Y
D000485:Allergens / Q000276:immunology*; D000818:Animals; D039741:Antigens, Dermatophagoides / Q000276:immunology*; D002478:Cells, Cultured; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D004804:Eosinophils / Q000187:drug effects / Q000201:enzymology / Q000276:immunology*; D020869:Gene Expression Profiling; D006801:Humans; D007113:Immunity, Innate; D016906:Interleukin-9 / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D039981:Pyroglyphidae / Q000276:immunology*; D044464:Receptor, PAR-2 / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012221:Rhinitis, Allergic, Perennial / Q000201:enzymology / Q000276:immunology*; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D013450:Sulfones / Q000494:pharmacology; D013997:Time Factors; D015854:Up-Regulation
D000485:Allergens; D039741:Antigens, Dermatophagoides; D016207:Cytokines; C508607:IL9 protein, human; D016906:Interleukin-9; D008070:Lipopolysaccharides; D044464:Receptor, PAR-2; D015842:Serine Proteinase Inhibitors; D013450:Sulfones; C002010:4-(2-aminoethyl)benzenesulfonylfluoride