Neutrophil activation by anti-proteinase 3 antibodies in Wegener's granulomatosis: role of exogenous arachidonic acid and leukotriene B4 generation.
Among the anti-neutrophil cytoplasmic antibodies (ANCA), those targeting proteinase 3 (PR3) have a high specificity for Wegener's granulomatosis (WG). It is known that a preceding priming of neutrophils with cytokines is a prerequisite for membrane surface expression of PR3, which is then accessible to autoantibody binding. Employing a monoclonal antibody directed against human PR3 and ANCA-positive serum from WG patients with specificity for PR3, we now investigated the role of free arachidonic acid (AA) in autoantibody-related human neutrophil activation. Priming of neutrophils with tumor necrosis factor (TNF-alpha) for 15 min or exposure to anti-PR3 antibodies or incubation with free AA (10 microM) as sole events did not provoke superoxide generation, elastase secretion or generation of 5-lipoxygenase products of AA. Similarly, the combination of TNF-alpha-priming and AA incubation was ineffective. When TNF-alpha-primed neutrophils were stimulated by anti-PR3 antibodies, superoxide and elastase secretion was provoked in the absence of lipid mediator generation. However, when free AA was additionally provided, a strong activation of the 5-lipoxygenase pathway was demasked, with the appearance of excessive quantities of leukotriene (LT)B4, LTA4, and 5-hydroxyeicosatetraenoic acid. Moreover, superoxide and elastase secretion were markedly amplified, and studies with 5-lipoxygenase inhibitors and a LTB4-antagonist demonstrated this was due to an LTB4-related autocrine loop of cell activation. In contrast, the increased synthesis of platelet-activating factor in response to TNF-alpha-priming and anti-PR3 stimulation did not contribute to the amplification loop of neutrophil activation under the given conditions. We conclude that anti-PR3 antibodies are potent inductors of the 5-lipoxygenase pathway in primed human neutrophils, and extracellular free AA, as provided at an inflammatory focus, synergizes with the autoantibodies to evoke full-blown lipid mediator generation, granule secretion and respiratory burst. Such events may be enrolled in the pathogenesis of focal necrotizing vascular injury in Wegener's granulomatosis.
Grimminger
F
F
Department of Internal Medicine, Justus-Liebig-University, Giessen, Germany.
Hattar
K
K
Papavassilis
C
C
Temmesfeld
B
B
Csernok
E
E
Gross
W L
WL
Seeger
W
W
Sibelius
U
U
D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism; D016718:Arachidonic Acid / Q000378:metabolism*; D001323:Autoantibodies / Q000276:immunology*; D014890:Granulomatosis with Polyangiitis / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D019272:Leukocyte Elastase / Q000378:metabolism; D007975:Leukotriene B4 / Q000378:metabolism*; D053146:Myeloblastin; D018375:Neutrophil Activation; D009504:Neutrophils / Q000187:drug effects; D012697:Serine Endopeptidases / Q000276:immunology*; D013481:Superoxides / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D001323:Autoantibodies; D014409:Tumor Necrosis Factor-alpha; D013481:Superoxides; D007975:Leukotriene B4; D016718:Arachidonic Acid; D001094:Arachidonate 5-Lipoxygenase; D012697:Serine Endopeptidases; D019272:Leukocyte Elastase; D053146:Myeloblastin