Defensin Interferes with the Activation of Neutrophil NADPH Oxidase a Cell-Free System

Tal, Tal; Aviram, Irit

doi:10.1006/bbrc.1993.2297

Cited by 10 publications

(8 citation statements)

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“…In previous communications we showed that a cationic protein(s) of neutrophil granules blocked cell-free activation of the NADPH oxidase [8,11]. This inhibitory activity of the extract was heat stable and insensitive to protease inhibitors, PMSF, and leupeptin [8].…”

Section: Discussionmentioning

confidence: 82%

“…In another study we demonstrated that human defensin (HNP-1), a representative of a family of 3.5-kDa cationic antimicrobial proteins of azurophilic granules [9,10], was capable of an effective blockade of NADPH oxidase activation in vitro (EC 50 ϭ 1.5 µM) [11]. The possibility that granule protein(s) released from activated cells may act in vivo as endogenous inhibitor(s) of excessive activation of the oxidase to prevent overproduction of oxygen radicals prompted us to further explore the inhibitory granule proteins and to attempt their identification.…”

Section: Introductionmentioning

confidence: 99%

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Cationic proteins of neutrophil azurophilic granules: protein-protein interaction and blockade of NADPH oxidase activation

Tal

Sharabani

Aviram

1998

Journal of Leukocyte Biology

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We have previously reported inhibition of cell-free activation of the neutrophil superoxidegenerating NADPH oxidase by a soluble cationic protein of neutrophil granules and by low concentrations of human defensin. Subcellular fractionation carried out in the current study indicated that the inhibitory substance was derived from azurophilic granules, was released into the medium on cell stimulation, and was resistant to phenylmethylsulfonyl fluoride (PMSF). Phorbol ester was the most effective stimulus for the release of the blocking activity. The possibility was raised that granule protein(s) act in vivo as negative modulators of superoxide production. Gel filtration of granule extract revealed a markedly retarded protein peak exhibiting oxidase-blocking activity and containing lysozyme as the main protein. Because lysozyme did not exert inhibitory effects on oxidase activation, association of the inhibitory protein with lysozyme was assumed. Indeed a column of immobilized lysozyme retained a fraction of the granule extract's oxidase-blocking activity. Elution with a low-pH buffer recovered a component capable of inhibition of the NADPH oxidase in stimulated neutrophils and in the cell-free system. The main 29-kDa protein band in the eluted fraction was identified as proteinase 3, a serine protease of azurophilic granules. Enzymatically active as well as PMSF-blocked conventionally purified proteinase 3 interfered with phorbol myristate acetateinduced superoxide release. These findings support the hypothesis that exocytosed granule constituents may prevent excessive activation of the NADPH oxidase.

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Section: Discussionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Cationic proteins of neutrophil azurophilic granules: protein-protein interaction and blockade of NADPH oxidase activation

Tal

Sharabani

Aviram

1998

Journal of Leukocyte Biology

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“…Recently several cationic peptides have been shown to inhibit NADPH oxidase activation. Tal et al [32] reported that defensin, a cellular cationic peptide, inhibits the activation of the oxidase, and the inhibition was relieved by increasing the concentration of p47phox. Also the synthetic peptides RGVHFIF (which corresponds to the C-terminus of the cyt.b &&) β-subunit [33]) and CPPPVKKRKRK (the C-terminus of rac 1 [23]) strongly inhibit the oxidase activation.…”

Section: Discussionmentioning

confidence: 99%

Spermine suppresses the activation of human neutrophil NADPH oxidase in cell-free and semi-recombinant systems

Ogata

Nishimoto

Uhlinger

et al. 1996

Biochemical Journal

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Spermine, a cellular polyamine, down-regulates O2- generation in human neutrophils stimulated by receptor-linked agonist [Ogata, Tamura and Takeshita (1992) Biochem. Biophys. Res. Commun. 182, 20-26]. In this study, to elucidate the mechanism for the inhibition, the effect of spermine on cell-free activation of the O2- generating enzyme (NADPH oxidase) was examined. Spermine suppressed the SDS-induced activation of NADPH oxidase in a dose-dependent manner with an IC50 of 18 microM. The inhibition was specific for spermine over its precursor amines, spermidine and putrescine. Spermine did not alter the Km for NADPH or the optimal concentration of SDS for activation. The amine was inhibitory only when added before activation, indicating that it affects the activation process rather than the enzyme's activity. An increased concentration of cytosol partly prevented the inhibition by spermine. In semi-recombinant cell-free system, spermine inhibited the activation of NADPH oxidase as effectively as in the cell-free system (IC50 = 13 microM). Pretreatment of each recombinant cytosolic component with spermine revealed that they (especially p67phox) are sensitive to spermine. These results suggest that spermine interacts with cytosolic component(s) and impairs the assembly of NADPH oxidase.

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“…Defensins have been shown to interfere with the activation of neutrophil superoxide-generating NADPH oxidase [131,132]. Reactive oxygen intermediates generated by the phagocyte NADPH oxidase are critically important components of host defense.…”

Section: Immune Modulating Activities Of Cationic Peptidesmentioning

confidence: 99%

Design of Host Defence Peptides for Antimicrobial and Immunity Enhancing Activities

McPhee¹,

Scott²,

Hancock

2005

CCHTS

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Host defense peptides are a vital component of the innate immune systems of humans, other mammals, amphibians, and arthropods. The related cationic antimicrobial peptides are also produced by many species of bacteria and function as part of the antimicrobial arsenal to help the producing organism reduce competition for resources from sensitive species. The antimicrobial activities of many of these peptides have been extensively characterized and the structural requirements for these activities are also becoming increasingly clear. In addition to their known antimicrobial role, many host defense peptides are also involved in a plethora of immune functions in the host. In this review, we examine the role of structure in determining antimicrobial activity of certain prototypical cationic peptides and ways that bacteria have evolved to usurp these activities. We also review recent literature on what structural components are related to these immunomodulatory effects. It must be stressed however that these studies, and the area of peptide research, are still in their infancy.

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Defensin Interferes with the Activation of Neutrophil NADPH Oxidase a Cell-Free System

Cited by 10 publications

References 0 publications

Cationic proteins of neutrophil azurophilic granules: protein-protein interaction and blockade of NADPH oxidase activation

Cationic proteins of neutrophil azurophilic granules: protein-protein interaction and blockade of NADPH oxidase activation

Spermine suppresses the activation of human neutrophil NADPH oxidase in cell-free and semi-recombinant systems

Design of Host Defence Peptides for Antimicrobial and Immunity Enhancing Activities

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