Eosinophil major basic protein: first identified natural heparanase-inhibiting protein.
BACKGROUND
Heparanase and eosinophils are involved in several diseases, including inflammation, cancer, and angiogenesis.


OBJECTIVE
We sought to determine whether eosinophils produce active heparanase.


METHODS
Human peripheral blood eosinophils were isolated by immunoselection and tested for heparanase protein (immunocytochemistry, Western blot), mRNA (RT-PCR) and activity (Na(2)[(35)S]O(4)-labeled extracellular matrix degradation) before and after activation. Heparanase intracellular localization (confocal laser microscopy) and ability to bind to eosinophil major basic protein (MBP) were also evaluated (immunoprecipitation). A model of allergic peritonitis resulting in eosinophilia was induced in TNF knockout and wild-type mice for in vivo studies.


RESULTS
Eosinophils synthesized heparanase mRNA and contained heparanase in the active (50-kd) and latent (65-kd) forms. Heparanase partially co-localized with and was bound to MBP. No heparanase enzymatic activity was detected in eosinophils resting or activated with various agonists, including GM-CSF/C5a. Eosinophil lysates and MBP inhibited recombinant heparanase activity in a concentration-dependent manner (100%, 2 x 10(-7) mol/L). Eosinophil peroxidase and eosinophil cationic protein, but not myelin basic protein or compound 48/80, partially inhibited heparanase activity. Poly-l-arginine at very high concentrations caused an almost complete inhibition. In allergic peritonitis, heparanase activity in the peritoneal fluid inversely correlated with eosinophil number.


CONCLUSIONS
MBP is the first identified natural heparanase-inhibiting protein. Its presence in the eosinophil granules might indicate a protective function of these cells in diseases associated with inflammation and cancer progression.
Temkin
Vladislav
V
Department of Pharmacology, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91120, Israel.
Aingorn
Helena
H
Puxeddu
Ilaria
I
Goldshmidt
Orit
O
Zcharia
Eyal
E
Gleich
Gerald J
GJ
Vlodavsky
Israel
I
Levi-Schaffer
Francesca
F
D000818:Animals; D001798:Blood Proteins / Q000502:physiology*; D002478:Cells, Cultured; D003594:Cytoplasmic Granules / Q000378:metabolism; D047091:Eosinophil Granule Proteins; D004804:Eosinophils / Q000378:metabolism / Q000473:pathology / Q000502:physiology; D019763:Heparin Lyase / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006967:Hypersensitivity / Q000150:complications; D007958:Leukocyte Count; D051379:Mice; D010538:Peritonitis / Q000209:etiology / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D012260:Ribonucleases / Q000502:physiology*; D014018:Tissue Distribution
D001798:Blood Proteins; D047091:Eosinophil Granule Proteins; D012333:RNA, Messenger; D012260:Ribonucleases; D019763:Heparin Lyase