Converting enzyme-independent release of tumor necrosis factor α and IL-1β from a stimulated human monocytic cell line in the presence of activated neutrophils or purified proteinase 3

Abstract

Two important cytokines mediating inf lammation are tumor necrosis factor ␣ (TNF␣) and IL-1␤, both of which require conversion to soluble forms by converting enzymes. The importance of TNF␣-converting enzyme and IL-1␤-converting enzyme in the production of circulating TNF␣ and IL-1␤ in response to systemic challenges has been demonstrated by the use of specific converting enzyme inhibitors. Many inf lammatory responses, however, are not systemic but instead are localized. In these situations release and͞or activation of cytokines may be different from that seen in response to a systemic stimulus, particularly because associations of various cell populations in these foci allows for the exposure of procytokines to the proteolytic enzymes produced by activated neutrophils, neutrophil elastase (NE), proteinase 3 (PR3), and cathepsin G (Cat G). To investigate the possibility of alternative processing of TNF␣ and͞or IL-1␤ by neutrophil-derived proteinases, immunoreactive TNF␣ and IL-1␤ release from lipopolysaccharide-stimulated THP-1 cells was measured in the presence of activated human neutrophils. Under these conditions, TNF␣ and IL-1␤ release was augmented 2-to 5-fold. In the presence of a specific inhibitor of NE and PR3, enhanced release of both cytokines was largely abolished; however, in the presence of a NE and Cat G selective inhibitor, secretory leucocyte proteinase inhibitor, reduction of the enhanced release was minimal. This finding suggested that the augmented release was attributable to PR3 but not NE nor Cat G. Use of purified enzymes confirmed this conclusion. These results indicate that there may be alternative pathways for the production of these two proinf lammatory cytokines, particularly in the context of local inf lammatory processes.

Activation of Human Oral Epithelial Cells by Neutrophil Proteinase 3 Through Protease-Activated Receptor-2

“…PR3 is a major target Ag of antineutrophil cytoplasmic Abs (15, 16) and degrades extracellular matrix proteins (13). PR3 is also shown to activate many types of cells (12,(17)(18)(19)(20), although the underlying mechanism was unclear. Therefore, the present study may provide one of the mechanisms of the cell activation by PR3 through PAR-2, and suggests that PR3 could activate the PAR-2-expressing cells, and regulate a number of inflammatory processes, and that the control of PAR-2-activating proteinases including PR3 at inflammatory sites might be beneficial in the regulation of inflammation.…”

“…The amidolytic activity of PR3 was assayed with 0.625 mM Boc-Ala-ONp for 10 -30 min at 25°C in 0.1 M HEPES buffer containing 0.1 M NaCl, 10 mM CaCl 2 , 0.005% Triton X-100, and 5% DMSO, pH 7.5, as described previously (18,34). The formation of the p-nitrophenol product was monitored at 405 nm using the Softmax data analysis program (Molecular Devices).…”

“…PR3 is a major target Ag of anti-neutrophil cytoplasmic Abs in Wegener's granulomatosis, a debilitating autoimmune disease characterized by necrotizing vasculitis (15,16). It has recently been shown that PR3 exhibits many biological functions, including the degradation of extracellular matrix proteins (13), regulation of myeloid differentiation (12,17), enhancement of TNF-␣ and IL-1␤ release from human monocytic cell lines (18), production of IL-8 and monocyte chemoattractant protein-1 (MCP-1) by human endothelial cells (19,20), and antibacterial action (21), all of which indicate that cell-bound and secreted soluble PR3 actively contribute to inflammatory processes, although the underlying mechanism is unclear to date.…”

Quantum Proteolytic Activation of Chemokine CCL15 by Neutrophil Granulocytes Modulates Mononuclear Cell Adhesiveness

“…To test this hypothesis, the specific elastase inhibitor elastatinal and secretory leukocyte proteinase inhibitor (SLPI), which is known to inhibit cathepsin G and elastase, but not proteinase 3, were tested (47). Whereas elastatinal only partially inhibited the processing of CCL15, SLPI inhibited the processing of CCL15 almost totally (Fig.…”

NADPH oxidase derived reactive oxygen species are involved in human neutrophil IL‐1β secretion but not in inflammasome activation

“…In contrast, the inflammasome including NLR family pyrin domain containing 3 (NLRP3) has been also implicated in the production of mature IL-1β in response to host-derived stress signals such as extracellular ATP, monosodium urate (MSU), and amyloid-β, as well as crystalline and particulate substances from the environment such as silica, asbestos, and aluminum hydroxide [7]. On the other hand, pro-IL-1β can also be released from cells and cleaved extracellularly by other proteases into mature IL-1β as has been shown for neutrophil proteinase 3 (PR3), elastase, and cathepsin G [8,9].Given the structural and chemical divergence between stimuli that lead to NLRP3 inflammasome activation, it has been proposed that these stimuli may elicit common signals recognized by NLRP3, such as: (i) a decrease in intracellular potassium levels, (ii) the presence in cytoplasm of lysosomal proteases due to phagolysosomal membrane disruption induced by phagocytosis of particulate stimuli, and (iii) the generation of intracellular ROS [10]. However, controversial findings have been made regarding the role of ROS in IL-1β maturation and release.…”