Influence of the Xanthine Derivate HWA 138 on Endotoxin-Related Coagulation Disturbances: Effects in Non-Sensitized vs D-Galactosamine Sensitized Rats

Review: D-Galactosamine lethality model: scope and limitations

D-Galactosamine (D-galN) is well established as sensitizing mice and other animals to the lethal effects of TNF, specifically, and by several orders of magnitude. Protection by anti-TNF neutralizing antibody is complete, as is (metabolically-based) protection by uridine. Sensitization occurs regardless of the origin of the released TNF, whether it is released from macrophages and/or T-cells. The same is true for the challenging agent which leads to the release of TNF, whether it is endotoxin, a superantigen, lipoprotein, bacterial DNA, or bacteria, either killed or proliferating. Most studies have utilized endotoxin as the challenging agent, and more than 70 agents have been reported to confer protection against LPS and/or TNF challenge in the model. The model has provided new insight regarding modes of protection, including from dexamethasone, which protects against challenge from LPS but not from challenge by TNF. The D-galN lethality model has also been used to test for synergistic behavior between different bacterial components, and to test for lethality when only small amounts of the challenging agent are available (lipid A chemistry).

Effects of antibiotic therapy on Pseudomonas aeruginosa-induced lung injury in a rat model

The effect of antibiotics on the acute lung injury induced by virulent Pseudomonas aeruginosa PA103 was quantitatively analyzed in a rat model. Lung injury was induced by the instillation of PA103 directly into the right lower lobes of the lungs of anesthetized rats. The alveolar epithelial injury, extravascular lung water, and total plasma equivalents were measured as separate, independent parameters of acute lung injury. Four hours after the instillation of PA103, all the parameters were increased linearly depending on the dose of P. aeruginosa. Next, we examined the effects of intravenously administered antibiotics on the parameters of acute lung injury in D-galactosamine-sensitized rats. One hour after the rats received 10(7) CFU of PA103, an intravenous bolus injection of aztreonam (60 mg/kg) or imipenem-cilastatin (30 mg/kg) was administered. Despite an MIC indicating resistance, imipenem-cilastatin improved all the measurements of lung injury; in contrast, aztreonam, which had an MIC indicating sensitivity, did not improve any of the lung injury parameters. The antibiotics did not generate different quantities of plasma endotoxin; therefore, endotoxin did not appear to explain the differences in lung injury. This in vivo model is useful to quantitatively compare the efficacies of parenteral antibiotic administration on Pseudomonas airspace infections.

Effects on complement activation and cytokine (TNF-alpha and IL-8) release of infusion of anti-TNF-antibodies or a xanthine derivative (HWA 138) in septic baboons

BACKGROUND

Sepsis and septic shock lead to activation of the complement cascade and to the release of pro-inflammatory cytokines.

METHODS

The effects of E coli infusion and of infusion of anti-TNF antibodies and a xanthine derivative (HWA 138) on complement activation and cytokine release was evaluated in 17 baboons. All animals received 5 x 10(8) live bacteria per kg body weight. Five animals received only bacteria, five received in addition 0.5 mg per kg body weight of anti-TNF-antibody, and seven received an infusion of 6 mg per kg body weight of HWA 138 in addition to the bacteria.

RESULTS

In baboons receiving 5 x 10(8) live E coli per kg body weight increased plasma levels of TCC, TNF-alpha and IL-8 were found. The release of TNF-alpha was lower in the group receiving HWA 138 at 2 h after the infusion. In baboons receiving an infusion of anti-TNF antibody the concentration of IL-8 was lower at 2 and 4 h than in animals receiving just E coli or HWA 138.

CONCLUSION

Infusion of anti-TNF-antibody before E coli infusion will decrease the formation of IL-8. Infusion of HWA 138 before the E coli infusion will also inhibit the formation of TNF-alpha.