Tumour necrosis factor-alpha (TNF-alpha) is a potent pro-inflammatory and immunomodulatory cytokine implicated in inflammatory conditions such as rheumatoid arthritis, Crohn's disease, multiple sclerosis and the cachexia associated with cancer or human immunodeficiency virus infection. TNF-alpha is initially expressed as a 233-amino-acid membrane-anchored precursor which is proteolytically processed to yield the mature, 157-amino-acid cytokine. The processing enzyme(s) which cleave TNF-alpha are unknown. Here we show that the release of mature TNF-alpha from leukocytes cultured in vitro is specifically prevented by synthetic hydroxamic acid-based metalloproteinase inhibitors, which also prevent the release of TNF-alpha into the circulation of endotoxin challenged rats. A recombinant, truncated TNF-alpha precursor is cleaved to biologically active, mature TNF-alpha by several matrix metalloproteinase enzymes. These results indicate that processing of the TNF-alpha precursor is dependent on at least one matrix metalloproteinase-like enzyme, inhibition of which represents a novel therapeutic mechanism for interfering with TNF-alpha production.

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Tumor necrosis factor-alpha (TNF-alpha) is released from a cell membrane-anchored precursor by proteolytic cleavage. We have shown that broad spectrum synthetic inhibitors of matrix metalloproteinases (MMPs) prevent the processing of the TNF precursor but do not inhibit the release of other cytokines. Purified MMPs, stromelysin, matrilysin, collagenase, and the gelatinases can all cleave a recombinant pro-TNF substrate to yield mature TNF. MMP inhibitors prevent the rise in blood levels of TNF after endotoxin administration in rats and are effective in animal models of inflammatory disease such as adjuvant arthritis. Drugs that inhibit MMP action and TNF release show great promise for the treatment of autoimmune inflammatory diseases.

is a genetically engineered variant of human macrophage inflammatory protein-la with improved solution properties. We show here that it mobilizes stem cells into the peripheral blood. We investigated the mobilizing effects of 88-10010 on the numbers of circulating 8-day spleen colony-forming units (CFU-S8), CFU-S,2, and progenitors with marrow repopulating ability (MM). A single subcutaneous dose of 88-10010 caused a twofold increase in circulating numbers of CFU-SI, CFU-S12, and M M 30 minutes after dosing. We also investigated the effects of granulocyte colonystimulating factor (G-CSF) and the combination of G-CSF with BB-10010 on progenitor mobilization. Two days of G-CSF treatment increased circulating CFU-Ss, CFU-SI2, and M M progenitors by 25.7-, 19.8-, and 27.7-fold. A single administration of BB-l0010 after 2 days of G-CSF treatment increased circulating CFU-S8, CFU-SI2, and M M even further to 38-, 33-, and 1 00-fold. Splenectomy resulted in increased T The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked ''advertisement'' in accordnnce with 18 U.S.C. section 1734 solely to indicate this fact. Great Britain and British Biotech Pharmaceuticals Ltd. 0 1995 by The American Society of Hematology. 0006-4971/95/8512-0044$3.00/0 3412 MATERIALS AND METHODSMice. Male B6D2F1 mice between 10 and 12 weeks of age were used throughout. They were allowed food and water ad libitum for the duration of the studies and all experimental procedures were