Pentoxifylline suppression of tumor necrosis factor gene transcription

Pentoxifylline decreases lung injury after intravenous endotoxin; the mechanism is unknown. Tumor necrosis factor-alpha (TNF) is secreted by macrophages in response to endotoxin and mediates some of the toxicity of endotoxin. This study investigates the effects of pentoxifylline on endotoxin-stimulated TNF production in vitro and in vivo. Pentoxifylline concentrations of 100 and 1000 micrograms/ml inhibited TNF production by murine adherent peritoneal exudate cells incubated with endotoxin 1 microgram/ml. Similarly, pentoxifylline at 100 and 1000 micrograms/ml decreased the number of available TNF messenger RNA transcripts in peritoneal exudate cells assessed by Northern blot. Pentoxifylline had no effect on TNF mRNA stability, but appeared to act by inhibiting the rate of TNF mRNA production (transcription). In murine in vivo experiments at each dose of endotoxin administered from 0.01 to 30 mg/kg, pentoxifylline treatment significantly reduced serum TNF levels, suggesting a favorable shift of the endotoxin dose-response curve. Expression of murine TNF gene in the livers of these animals showed fewer TNF transcripts in the pentoxifylline-treated animals compared to controls. Pentoxifylline inhibited endotoxin-induced TNF production both in vivo and in vitro and exerted this control by inhibiting endotoxin-induced transcription of the TNF gene. This study suggests that pentoxifylline may ameliorate endotoxic shock by decreasing macrophage TNF production.