The effect of tumour necrosis factor (TNF) inhibitors in Clostridium difficile toxin-induced paw oedema and neutrophil migration.

Clostridium difficile produces a potent enterotoxin and a cytotoxin, toxin A and toxin B, respectively. These toxins are associated with pseudomembranous colitis and antibiotic-associated diarrhoea. In the present study, we investigated the oedematogenic activity of both toxins, characterizing the time-course and dose-response of this pro-inflammatory event. We also explored the effects of two inhibitors of tumour necrosis factor (TNF) production, thalidomide and pentoxifylline, in neutrophil recruitment and the oedematogenic activity of these toxins. Subplantar injection of toxin A induced paw oedema with a maximal response at 1 microg, reaching a maximal value 9 hr after toxin A challenge (toxin A 1 microg:1.39+/-0.09 ml). Toxin B also showed a dose-dependent oedematogenic activity with a late peak at 24 hr and a maximal response at a dose of 0.1 microg (toxin B 0.1 microg:1.74+/-0.12 ml). Pentoxifylline, but not thalidomide, significantly reduced the oedema induced by Toxin A (pentoxifylline 135 mg/kg:60% of inhibition) and Toxin B (pentoxifylline 135 mg/kg:33.6% of inhibition). Both thalidomide and pentoxifylline were able to significantly reduce neutrophil influx into the peritoneal cavities of rats evoked with Toxin A (thalidomide 45 mg/kg: 53.1% of inhibition; pentoxifylline 45 mg/kg:47.1% of inhibition) and Toxin B (thalidomide 45 mg/kg:46.8% of inhibition; pentoxifylline 45 mg/kg:63.1% of inhibition). This study demonstrates the oedematogenic activities of both toxins with distinct potencies and time-courses. These data also show an inhibitory effect of pentoxifylline in toxin A and B-induced paw oedema. Furthermore, both pentoxifylline and thalidomide significantly inhibited the Clostridium difficile toxins-induced neutrophil migration.