Review
The physiological role and pharmacological potential of nitric oxide in neutrophil activation

https://doi.org/10.1016/S1567-5769(01)00094-7Get rights and content

Abstract

There is contention over whether human neutrophils produce physiologically significant levels of nitric oxide (NO) during inflammatory reactions. Nevertheless, regardless of its cell source, NO does exert regulatory effects on neutrophil function. Depending on experimental conditions, NO can either inhibit or enhance neutrophil activation, in both cases probably acting through cyclic GMP. The explanation for these apparently contradictory findings may be that the effect depends upon the concentration of NO: low concentrations of NO being stimulatory and high concentrations inhibitory. Nitrite, produced at high concentrations from NO during inflammation, can react with neutrophil myeloperoxidase-derived hypochlorous acid (HOCl) to form the active oxidant nitryl chloride, a species capable of nitrating tyrosine and tyrosyl residues on proteins. Whether nitryl chloride acts to limit or amplify the oxidant effects of myeloperoxidase is not yet clear, although formation of nitrotyrosine has been linked with nitration of phagocytosed bacteria. Clearly, a better understanding of the inflammatory effects of NO on neutrophils is needed before the therapeutic potential of NO donors or inhibitors in inflammation can be realised.

Introduction

Neutrophils comprise a fundamental component of the non-specific immune response to bacterial infection. The neutrophil response is characterised by adhesion to the vascular endothelium, followed by migration into tissues, oxygen radical-dependent killing of microbes, and elimination of microbes and tissue debris by phagocytosis. Since the agents released by activated neutrophils are potentially toxic to host tissues, neutrophils are subsequently removed by the process of apoptosis and are engulfed by macrophages to resolve the inflammatory response. Thus, modulation of the activation status of the neutrophil is of key importance in determining the balance between immune defense and host injury.

The aim of this review is to examine the role of nitric oxide (NO) in modulating neutrophil function. Effects of NO on the neutrophil functions detailed above will be discussed to elucidate the physiological role of endogenous NO, as well as its pharmacological potential in clinical situations.

Section snippets

NO production by neutrophils

Several studies have reported NO production by neutrophils, but others have claimed little or no NO production by these cells. For example, NO synthesis coincident with neutrophil chemotaxis has been detected by functional NO activity [1], [2], chemically [3], [4], [5] and by ADP ribosylation of proteins [6]. Human blood neutrophils stimulated in vitro with monocyte-derived cytokines and neutrophils from inflamed exudates are reported to express inducible NO synthase (iNOS) [7], [8].

Role of NO in neutrophil chemotaxis

There is considerable evidence that NO and cyclic GMP act as endogenous mediators of the chemotactic response of neutrophils. NOS inhibitors such as NG-monomethyl l-arginine (l-NMMA), NG-nitro-l-arginine methyl ester (l-NAME) and canavanine (l-CAN) all inhibited neutrophil chemotaxis induced by the bacterial peptide n-formyl-methionyl-leucyl-phenylalanine (fMLP) (Table 1), supporting a role for NO as a mediator of chemotaxis. Nω-nitro l-arginine (l-NNA) was ineffective in this respect, perhaps

NO in neutrophil adhesion

The migration of neutrophils from the blood though the endothelium to the site of inflammation requires highly coordinated cell–cell adhesive interactions between neutrophils and the endothelium. Selectins mediate the initial, low affinity adherence of neutrophils when rolling along the endothelium [24], whereas activation of neutrophil integrin adhesion molecules, and their interaction with endothelial immunoglobulins, enables transmigration of neutrophils to occur [25].

Neutrophil aggregation

NO and generation of reactive oxygen species by neutrophils

Generation of superoxide (O2) during the respiratory burst results from the assembly and activation of the NADPH oxidase-dependent transmembrane electron transport chain. This oxidase activation is essential for the bactericidal function of neutrophils [45] and consequently, their toxic potential. Several studies have looked at the effects of NOS inhibitors on the neutrophil respiratory burst (Table 2) but only one [104] revealed the involvement of NO. This cannot relate to lack of NOS

NO and neutrophil phagocytosis

Less work has been carried out looking at NO and neutrophil phagocytosis. An early study suggested that endogenous NO could play a role in human neutrophil phagocytosis since anucleate, granule-poor neutrophil cytoplasts decreased their uptake and killing of staphylococci from supernatants in the presence of the NOS inhibitor l-NMMA, an effect that was reversed by l-arginine [68]. Subsequently l-arginine supplementation was shown to increase phagocytosis of staphylococcus by human neutrophils

NO and neutrophil apoptosis

The role of endogenous NO in neutrophil apoptosis is less clear. The guanylate cyclase inhibitor LY 83583 increased the rate of spontaneous neutrophil apoptosis suggesting that cyclic GMP may limit neutrophil apoptosis [71]. However, it has not been shown that this cyclic GMP effect is subsequent to stimulation of guanylate cyclase by NO. Levels of neutrophil nitrite, a stable oxidation product of NO, increase as neutrophils undergo spontaneous apoptosis in culture [72]. However, since nitrite

Clinical significance of NO and neutrophils

In therapeutic terms, inhaled exogenous NO is being evaluated as a novel treatment for pulmonary arterial hypertension [76], [77] in adult respiratory distress syndrome. In addition to its vasodilator action, NO has anti-inflammatory action by reducing neutrophil superoxide anion generation [78], [79]. Similarly, inhaled NO prevents neutrophil-related lung injury in several animal models [80], [81].

Since exposure of neutrophils to clinically relevant concentrations of NO has been found to

Acknowledgements

I would like to thank Payong Wanikiat for performing the experiments on isolated neutrophils and with a rat model of ischaemia reperfusion injury, as part of her PhD thesis and for her thesis itself, which provided a starting point for the neutrophil and NO literature.

References (109)

  • G.M. Rubanyi et al.

    Inactivation of superoxide radicals produced by human leukocytes

    Biochem. Biophys. Res. Commun.

    (1991)
  • R.C. Allen et al.

    Evidence for the generation of an electronic excitation state(s) in human polymorphonuclear leukocytes and its participation in bacteriocidal activity

    Biochem. Biophys. Res. Commun.

    (1972)
  • R.A. Radi et al.

    Comparison of the effects of superoxide dismutase and cytochrome c on luminol chemiluminescence produced by xanthine oxidase-catalysed reactions

    Biochim. Biophys. Acta

    (1989)
  • P. Holm et al.

    Radical releasing properties of nitric oxide donors GEA 3162, SIN-1 and S-nitroso-N-acetylpenicillamine

    Eur. J. Pharmacol.

    (1998)
  • A. Van der Vliet et al.

    Formation of reactive nitrogen species during peroxidase-catalysed oxidation of nitrite. A potential additional mechanism of nitric oxide dependent toxicity

    J. Biol. Chem.

    (1997)
  • J.B. Sampson et al.

    Myeloperoxidase and horseradish peroxidase catalyse tyrosine nitration in proteins from nitrite and hydrogen peroxide

    Arch. Biochem. Biophys.

    (1998)
  • U. Burner et al.

    Mechanism of reaction of myeloperoxidase with nitrite

    J. Biol. Chem.

    (2000)
  • H. Kaur et al.

    Evidence for nitric oxide-mediated oxidative damage in chronic inflammation. Nitrotyrosine in serum and sinovial fluid from rheumatoid patients

    FEBS Lett.

    (1994)
  • R.E. Huie

    The reaction kinetics of NO2(·)

    Toxicology

    (1994)
  • S.J. Klebanoff

    Reactive nitrogen intermediates and antimicrobial activity: role of nitrite

    Free Radical Biol. Med.

    (1993)
  • M.F. McCarty

    The reported clinical utility of taurine in ischemic disorders may reflect a down-regulation of neutrophil activation and adhesion

    Med. Hypotheses

    (1999)
  • C. Ward et al.

    Induction of human neutrophil apoptosis by nitric oxide donors: evidence for a capsase-dependent, cyclic GMP-independent mechanism

    Biochem. Pharmacol.

    (2000)
  • N.L.A. Misso et al.

    Nitrite generation and antioxidant effects during neutrophil apoptosis

    Free Radical Biol. Med.

    (2000)
  • M.G. Blaylock et al.

    The effect of nitric oxide and peroxynitrite on apoptosis in human polymorphonuclear leukocytes

    Free Radical Biol. Med.

    (1998)
  • K. Chen et al.

    Expression of NOS II and its role in experimental small bowel ulceration in rats

    Surgery

    (1999)
  • S.S. Kaplan et al.

    Inhibition of chemotaxis with NG-monomethyl-l-arginine: a role for cyclic GMP

    Blood

    (1989)
  • T.A. Wyatt et al.

    Vimentin is transiently co-localised with phosphorylate by cyclic GMP-dependent protein kinase in formyl-peptide stimulated neutrophils

    J. Biol. Chem.

    (1991)
  • T.B. McCall et al.

    Synthesis of nitric oxide from l-arginine by neutrophils: release and interaction with superoxide anion

    Biochem. J.

    (1989)
  • D. Salvemini et al.

    Human neutrophils and mononuclear cells inhibit platelet aggregation by releasing a nitric oxide-like factor

    Proc. Natl. Acad. Sci. U. S. A.

    (1989)
  • A.R. Amin et al.

    Expression of nitric oxide synthase in human peripheral blood mononuclear cells and neutrophils

    J. Inflammation

    (1996)
  • T.J. Evans et al.

    Cytokine-treated human neutrophils contain inducible nitric oxide synthase that produces nitration of ingestion bacteria

    Proc. Natl. Acad. Sci. U. S. A.

    (1996)
  • O. Takeichi et al.

    Cytokine regulation on nitric oxide production in periapical periodontitis

    J. Dent. Res.

    (1998)
  • M.A. Wheeler et al.

    Bacterial infection induces nitric oxide synthase in human neutrophils

    J. Clin. Invest.

    (1997)
  • L. Yan et al.

    Human polymorphonuclear leukocytes lack detectable nitric oxide synthase activity

    J. Immunol.

    (1994)
  • A.M. Miles et al.

    Nitric oxide synthase in circulating vs. extravasated polymorphonuclear leukocytes

    J. Leukocyte Biol.

    (1995)
  • A. Dembinska-Kiec et al.

    A neutrophil-derived NO-synthase (NOS) inhibitor

    Agents Actions

    (1995)
  • S.S. Greenberg et al.

    Human and rat neutrophils constitutively express neuronal nitric oxide synthase mRNA

    Nitric Oxide

    (1998)
  • M.N. Ajuebor et al.

    Role of inducible nitric oxide synthase in the regulation of neutrophil migration in zymosan-induced inflammation

    Immunology

    (1998)
  • P. Ney et al.

    Nitrovasodilator-induced inhibition of LTB4 release from human PMN may be mediated by cyclic GMP

    Eicosanoids

    (1990)
  • P. Kubes et al.

    Nitric oxide: an endogenous modulator of leukocyte adhesion

    Proc. Natl. Acad. Sci. U. S. A.

    (1991)
  • K. Wenzel-Seifert et al.

    Differential inhibition and potentiation by cell-permeant analogues of cyclic AMP and cyclic GMP and NO-containing compounds of exocytosis in human neutrophils

    Naunyn-Schmiedeberg's Arch. Pharmacol.

    (1991)
  • P. Wanikiat et al.

    Investigation of the role of nitric oxide and cyclic GMP in both the activation and inhibition of human neutrophils

    Br. J. Pharmacol.

    (1997)
  • T. Siminiak et al.

    Nitric oxide donor SIN-1 inhibits neutrophil activation both directly and via a platelet-dependent mechanism

    J. Mol. Cell. Cardiol.

    (1992)
  • E. Moilanen et al.

    Inhibition by nitric oxide-donors of human polymorphonuclear leucocyte functions

    Br. J. Pharmacol.

    (1993)
  • T.F. Tedder et al.

    The selectins: vascular adhesion molecules

    FASEB J.

    (1995)
  • M.T. Carlos et al.

    Leukocyte–endothelial adhesion molecules

    Blood

    (1994)
  • R. Clancy et al.

    Nitric oxide stimulates ADP ribosylation of actin in association with the inhibition of actin polymerization in human neurophils

    J. Leukocyte Biol.

    (1995)
  • T.L. Gluckman et al.

    Regulation of leukocyte function by nitric oxide donors: the effect of S-nitroso–thiol complexes

    J. Toxicol. Environ. Health

    (2000)
  • O. Kosonen et al.

    Nitric oxide-releasing compounds inhibit neutrophil adhesion to endothelial cells

    Eur. J. Pharmacol.

    (1999)
  • M. Chello et al.

    Nitric oxide inhibits neutrophil adhesion during experimental extracorporeal circulation

    Anaesthesiology

    (1998)
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