| 1. |
- Tapper, Hans, et al.
(author)
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Secretion of heparin-binding protein from human neutrophils is determined by its localization in azurophilic granules and secretory vesicles.
- 2002
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In: Blood. - 0006-4971 .- 1528-0020. ; 99:5, s. 1785-93
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Journal article (peer-reviewed)abstract
- Human neutrophils have an important role in host defense against microbial infection. At different stages of an infectious process, neutrophils progressively up-regulate receptors and release various effector molecules. These are stored in several distinct types of granules with varying propensity to be secreted. Heparin-binding protein (HBP), also known as CAP37 or azurocidin, is a multifunctional, inactive serine-protease homologue. The present work shows that HBP is released from neutrophils on stimulation with secretagogues that do not trigger the secretion of azurophilic granule content. Therefore, the subcellular localization of HBP was investigated in more detail. Immunofluorescence microscopy revealed that HBP was localized close to the plasma membrane. Further analysis by fractionation of postnuclear supernatants from cavitated neutrophils showed that HBP is stored in azurophilic granules and secretory vesicles but that it is also detected to a minor extent in the plasma membrane. These findings were confirmed by immunoelectron microscopy showing that HBP colocalized with marker proteins of azurophilic granules and secretory vesicles. The presence of HBP in secretory vesicles possibly depends on the stage of cell differentiation, since the promyelocytic cell line HL-60 contains less HBP than mature neutrophils, stored exclusively in the less easily mobilized azurophilic granules. Our findings suggest that HBP can be synthesized or targeted to easily mobilized compartments at a late stage of neutrophil maturation. The ability of neutrophils to secrete HBP from secretory vesicles may be important for proinflammatory functions of this protein, such as the alteration of vascular permeability.
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| 2. |
- Gautam, Narinder, et al.
(author)
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Heparin-binding protein (HBP/CAP37): A missing link in neutrophil-evoked alteration of vascular permeability
- 2001
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In: Nature Medicine. - : Springer Science and Business Media LLC. - 1546-170X .- 1078-8956. ; 7:10, s. 1123-1127
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Journal article (peer-reviewed)abstract
- Polymorphonuclear leukocyte infiltration into tissues in host defense and inflammatory diseasecauses increased vascular permeability and edema formation through unknown mechanisms.Here, we report the involvement of a paracrine mechanism in neutrophil-evoked alteration inendothelial barrier function. We show that upon neutrophil adhesion to the endothelial lining,leukocytic 2 integrin signaling triggers the release of neutrophil-borne heparin-binding protein(HBP), also known as CAP37/azurocidin, a member of the serprocidin family of neutrophilcationic proteins. HBP induced Ca++-dependent cytoskeletal rearrangement and intercellular gapformation in endothelial-cell monolayers in vitro, and increased macromolecular efflux in microvesselsin vivo. Moreover, selective inactivation of HBP prevented the neutrophils from inducingendothelial hyperpermeability. Our data suggest a fundamental role of neutrophil-derivedHBP in the vascular response to neutrophil trafficking in inflammation. Targeting this moleculein inflammatory disease conditions offers a new strategy for prevention of endothelial barrierdysfunction caused by misdirected leukocyte activation.
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