A matrix metalloproteinase inhibitor prevents processing of tumor necrosis factor α (TNFα) and abrogates endotoxin-induced lethality

Excessive tumor necrosis factor α (TNFα) production in response to Gram-negative bacteremia or endotoxemia can often lead to hypotension, shock, and increased mortality. Current approaches used to block the deleterious effects of exaggerated TNFα production rely on monoclonal antibodies or immunoadhesins that bind TNFα and thus prevent the interaction with its cellular receptors. This report examines whether a previously described inhibitor of matrix metalloproteinases, GM-6001, can inhibit TNFα processing and release and attenuate endotoxin-induced mortality. In human peripheral blood mononuclear cells stimulated in vitro with 1 μg/mL endotoxin, GM-6001 at concentrations >5 μg/mL blocked release of TNFα, but did not affect the release of either IL-1β or IL-6. GM-6001 also inhibited the release of soluble TNF receptor (p75) from peripheral blood mononuclear cells stimulated with endotoxin and/or TNFα. To confirm the role of secreted TNFα in endotoxic shock-induced mortality, C57BL/6 mice were challenged with either endotoxin alone (500 μg/mouse) or endotoxin (100 ng/mouse) plus D-galactosamine (8 mg/mouse). GM-6001 pretreatment (100 mg/kg) significantly attenuated the 90-minute plasma TNFα response in both models and improved survival in mice treated with low-dose endotoxin plus D-galactosamine. However, plasma IL-1β and IL-6 concentrations at 90 min after endotoxin treatment were unaffected by GM-6001 following lethal endotoxin challenge, confirming the in vivo specificity of this matrix metalloproteinase inhibitor for TNFα processing. These findings demonstrate that a novel inhibitor of matrix metalloproteinases can prevent the release of TNFα both in vitro and in vivo, and can abrogate the harmful sequelae of endotoxemic shock.