Role of mitogen-activated protein kinases in activation of human neutrophils by antineutrophil cytoplasmic antibodies

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Item Type:	Article
Title:	Role of mitogen-activated protein kinases in activation of human neutrophils by antineutrophil cytoplasmic antibodies
Creators Name:	Kettritz, R., Schreiber, A., Luft, F.C. and Haller, H.
Abstract:	Antineutrophil cytoplasmic antibodies (ANCA) may be important in the pathophysiology of necrotizing vasculitis. ANCA activate human neutrophils primed with tumor necrosis factor-alpha (TNF-alpha) in vitro. TNF-alpha priming results in translocation of ANCA antigens to the cell surface, where they are recognized by the antibodies. The signaling mechanisms involved in TNF-alpha priming and subsequent ANCA-induced activation were investigated. TNF-alpha-primed neutrophils were stimulated with monoclonal antibodies (MAb) to human myeloperoxidase (MPO) and proteinase 3 (PR3), and with preparations of human ANCA (three patients with PR3-ANCA and two patients with MPO-ANCA). Respiratory burst was measured with superoxide dismutase-inhibitable ferricytochrome C reduction and using dihydro-rhodamine-1,2,3. Phosphorylation of p38 mitogen-activated protein kinase (p38-MAPK) and the extracellular signal-regulated kinase (ERK) were assessed by immunoblotting. ANCA-antigen translocation was studied by flow cytometry. The tyrosine phosphorylation inhibitor genistein, but not calphostin or staurosporin, resulted in a significant dose-dependent superoxide generation inhibition (11.6 +/- 1.7 nmol to 2.1 +/- 0.5 for PR3-ANCA, and 16.0 +/- 2.8 to 3.3 +/- 1.3 for MPO-ANCA). The p38-MAPK inhibitor (SB202190) and the ERK inhibitor (PD98059) diminished PR3-ANCA-mediated superoxide production dose dependently (11.6 +/- 1.7 nmol O(2)(-) to 1.9 +/- 0.6 with 50 microM SB202190 and 4.0 +/- 0.6 with 50 microM PD098059, respectively). For MPO-ANCA, the results were similar (16.0 +/- 2.8 nmol to 0.9 +/- 1.0 nmol with SB202190 and 6.4 +/- 2.4 nmol with PD98059, respectively). Western blot showed phosphorylation of both p38-MAPK and ERK during TNF-alpha priming. The p38-MAPK inhibitor and the ERK inhibitor showed the strongest effect on respiratory burst when added before TNF-alpha priming, further supporting an important role for both signaling pathways in the priming process. Flow cytometry showed that p38-MAPK inhibition decreased the translocation of PR3 (by 93 +/- 2%) and of MPO (by 64 +/- 2%). In contrast, no such effect was seen when ERK was inhibited. Thus, p38-MAPK and ERK are important for the TNF-alpha-mediated priming of neutrophils enabling subsequent ANCA-induced respiratory burst. However, both pathways show differential effects, whereby p38-MAPK controls the translocation of ANCA antigens to the cell surface.
Keywords:	Antineutrophil Cytoplasmic Antibodies, Genistein, Kinetics, Mitogen-Activated Protein Kinases, Myeloblastin, Naphthalenes, Neutrophils, Peroxidase, Phosphorylation, Respiratory Burst, Serine Endopeptidases, Signal Transduction, Staurosporine, Superoxides, Tumor Necrosis Factor-alpha, Tyrosine, p38 Mitogen-Activated Protein Kinases
Source:	Journal of the American Society of Nephrology
ISSN:	1046-6673
Publisher:	American Society of Nephrology
Volume:	12
Number:	1
Page Range:	37-46
Date:	January 2001
Official Publication:	http://jasn.asnjournals.org/cgi/content/abstract/12/1/37
PubMed:	View item in PubMed

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