Matrix metalloproteinase-9 in peripheral blood eosinophils.
BACKGROUND
Matrix metalloproteinases (MMPs) are major contributors to tumor invasion, remodeling of connective tissue and infiltration of inflammatory cells and may be important mediators in developing allergic inflammation. Overexpression of MMP-9 mRNA by eosinophils in the asthmatic airways has been reported. To clarify the relative significance of MMP as an inflammatory mediator from eosinophils, we determined the content of MMP-9 in the peripheral blood eosinophils and compared it with the other leukocyte fractions.


METHODS
Peripheral blood eosinophils, neutrophils, and mononuclear cells were purified from normal and allergic donors with Percoll gradient centrifugation and CD16 negative selection. Cell lysate and culture supernatants stimulated with IL-5, PAF, and PMA were tested for MMP-9 with gelatin zymography and ELISA.


RESULTS
The amount of MMP-9 in highly purified eosinophils, neutrophils, and mononuclear cells was 2.5 +/- 0.9, 4,073 +/- 581, and 7.6 +/- 1.4 ng/5 x 10(6) cells, respectively. There was no difference in MMP-9 content of eosinophils between normal donors and patients with asthma. Culture of peripheral blood eosinophils with IL-5 for 4 days did not induce MMP-9 production. The stimulation of eosinophils with PMA and other secretogogues caused only small amounts of MMP-9 secretion as compared with neutrophils.


CONCLUSIONS
These findings suggest that circulating eosinophils normally have only small amounts of MMP-9 and that eosinophils may need complex activation signals to produce significant amounts of MMP as seen in tissues of allergic inflammation.
Fujisawa
T
T
Department of Pediatrics, Mie National Hospital, Mie, Japan.
Kato
Y
Y
Terada
A
A
Iguchi
K
K
Kamiya
H
H
D001249:Asthma / Q000097:blood*; D004804:Eosinophils / Q000201:enzymology*; D006801:Humans; D007962:Leukocytes / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000097:blood*
D020780:Matrix Metalloproteinase 9