TNF-Induced Shedding of TNF Receptors in Human Polymorphonuclear Leukocytes: Role of the 55-kDa TNF Receptor and Involvement of a Membrane-Bound and Non-Matrix Metalloproteinase

• Published in: The Journal of immunology (1950) 2000-08, Vol.165 (4), p.2165-2172
• Main Authors: Dri, Pietro, Gasparini, Chiara, Menegazzi, Renzo, Cramer, Rita, Alberi, Lavinia, Presani, Gianni, Garbisa, Spiridione, Patriarca, Pierluigi
• Format: Article
• Language: English
• Subjects: ADAM Proteins; ADAM12 Protein; ADAM17 Protein; Antigens, CD - metabolism; Antigens, CD - physiology; Cell Membrane - drug effects; Cell Membrane - enzymology; Cell Membrane - immunology; Humans; Matrix Metalloproteinase Inhibitors; matrix metalloproteinases; Matrix Metalloproteinases - physiology; Membrane Proteins - biosynthesis; Membrane Proteins - chemistry; Membrane Proteins - physiology; Metalloendopeptidases - biosynthesis; Metalloendopeptidases - chemistry; Metalloendopeptidases - physiology; Muscle Proteins - biosynthesis; Muscle Proteins - physiology; Neutrophils - drug effects; Neutrophils - enzymology; Neutrophils - immunology; Neutrophils - metabolism; Phenanthrolines - pharmacology; Receptors, Tumor Necrosis Factor - antagonists & inhibitors; Receptors, Tumor Necrosis Factor - metabolism; Receptors, Tumor Necrosis Factor - physiology; Receptors, Tumor Necrosis Factor, Type I; Receptors, Tumor Necrosis Factor, Type II; Tissue Inhibitor of Metalloproteinase-1 - pharmacology; Tissue Inhibitor of Metalloproteinase-2 - pharmacology; Tumor Necrosis Factor-alpha - antagonists & inhibitors; Tumor Necrosis Factor-alpha - metabolism; Tumor Necrosis Factor-alpha - physiology; U937 Cells
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.165.4.2165

A down-modulation of both the 55-kDa (TNF-R55) and the 75-kDa (TNF-R75) TNF receptors is observed in neutrophils exposed to a variety of stimuli. Proteolytic cleavage of the extracellular region of both receptors (shedding) and, with TNF, internalization of TNF-R55 and shedding of TNF-R75 are the proposed mechanisms. We have characterized the TNF-induced shedding of TNF receptors in neutrophils and determined the nature of the involved proteinase. Neutrophils exposed to TNF release both TNF receptors. A release of TNF receptors comparable to that observed with TNF was induced with TNF-R55-specific reagents (mAbs and a mutant of TNF) but not with the corresponding TNF-R75-specific reagents. A hydroxamic acid compound (KB8301) almost completely inhibited shedding of TNF-R55 and to a lesser degree shedding of TNF-R75. KB8301 also inhibited FMLP-induced shedding to a similar extent. Shedding was also inhibited by 1,10-phenanthroline, but this effect was considered nonspecific as the compound, at variance with KB8301, almost completely inhibited TNF and FMLP-induced PMN activation. Diisopropylfluorophosphate partially inhibited shedding of TNF-R75, suggesting the contribution of a serine proteinase to the release of this receptor. Shedding activity was not affected by matrix metalloproteinases inhibitors nor was it released in the supernatants of FMLP-stimulated neutrophils. These results suggest that TNF induces release of its receptors, that such a release is mediated via TNF-R55, and that a membrane-bound and non-matrix metalloproteinase is involved in the process. The possibility that ADAM-17, which we show to be expressed in neutrophils, might be the involved proteinase is discussed.