Mite serine protease activates protease-activated receptor-2 and induces cytokine release in human keratinocytes.
BACKGROUND
House dust mites produce serine and cysteine proteases. Mite-derived proteases have been suggested to be involved in the pathogenesis of allergies; however, whether mite-derived serine protease activity can stimulate keratinocytes remains unknown.


METHODS
We examined the activation of primary human keratinocytes by serine protease-rich extract of whole mite culture and compared with that by recombinant group 1 allergens (rDer f 1 and rDer p 1), which exclusively exhibit cysteine protease activity.


RESULTS
Protease activity of whole mite culture extract (WCE), rDer f 1 and rDer p 1 induced the release of IL-8 and granulocyte-macrophage colony-stimulating factor. Protease activity of WCEs induced a significant upregulation of their mRNA expression but rDer f 1 had much less effect. Protease activity of the WCE stimulated intracellular Ca(2+) mobilization but rDer f 1 and rDer p 1 did not. The mobilization induced by agonists for the human protease-activated receptor (PAR)-2, an agonist peptide or trypsin, was diminished by pre-incubation of keratinocytes with WCE. rDer f 1 inefficiently cleaved a synthetic N-terminal peptide of PAR-2 at different sites from trypsin, but the resultant peptides did not stimulate the release of interleukin-8.


CONCLUSIONS
The results suggest that mite-derived serine protease activity may contribute to the pathogenesis of atopic dermatitis by activating keratinocytes via PAR-2 activation but cysteine protease activity of Der f 1 and Der p 1 acts via another mechanism.
Atopy Research Center, Juntendo University School of Medicine, Tokyo, Japan.
T
T
Kato
T
T
Takai
T
T
Fujimura
H
H
Matsuoka
T
T
Ogawa
K
K
Murayama
A
A
Ishii
S
S
Ikeda
K
K
Okumura
H
H
Ogawa
D000818:Animals; D039741:Antigens, Dermatophagoides / Q000378:metabolism / Q000494:pharmacology; D060829:Arthropod Proteins; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D003546:Cysteine Endopeptidases; D003876:Dermatitis, Atopic / Q000276:immunology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism; D015603:Keratinocytes / Q000187:drug effects / Q000276:immunology*; D010455:Peptides / Q000494:pharmacology; D039981:Pyroglyphidae / Q000201:enzymology* / Q000276:immunology; D012333:RNA, Messenger / Q000378:metabolism; D044464:Receptor, PAR-2 / Q000819:agonists / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D057057:Serine Proteases / Q000276:immunology* / Q000494:pharmacology
D039741:Antigens, Dermatophagoides; D060829:Arthropod Proteins; D016209:Interleukin-8; D010455:Peptides; D012333:RNA, Messenger; D044464:Receptor, PAR-2; D011994:Recombinant Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D057057:Serine Proteases; D003546:Cysteine Endopeptidases; C451159:Dermatophagoides farinae antigen f 1; C451162:Dermatophagoides pteronyssinus antigen p 1; D002118:Calcium