INTERLEUKIN-1 RECEPTOR BLOCKADE IMPROVES SURVIVAL AND HEMODYNAMIC PERFORMANCE IN ESCHERICHIA-COLI SEPTIC SHOCK, BUT FAILS TO ALTER HOST RESPONSES TO SUBLETHAL ENDOTOXEMIA

The present study was undertaken to evaluate the extent to which an endogenous interleukin-1 (IL-1) response contributes to the hemodynamic and metabolic consequences of sublethal endotoxemia or lethal Gram-negative septic shock. Young, healthy baboons received either a sublethal dose of lipopolysaccharide (LPS) or an LD100 of live Escherichia coli bacteria, and one half of the animals in each group were continuously infused with IL-1 receptor antagonist (IL-1ra). Plasma IL-1-beta was not detected in this model of endotoxemia. Administration of IL-1ra had only minimal effects on the modest hemodynamic and metabolic responses to sublethal endotoxemia, and did not attenuate the plasma cytokine response. In contrast, high circulating levels of IL-1-beta (range 300-800 pg/ml) were seen during lethal E. coli septic shock. IL-1 ra treatment significantly attenuated the decrease in mean arterial blood pressure (MAP) (from -72 +/- 8 to -43 +/- 6 mm Hg; P < 0.05) and cardiac output (from -0.81 +/- 0.17 to -0.48 +/- 0.15 liter/min; P < 0.05), and significantly improved survival from 43 to 100% at 24 h (P < 0.05). The plasma IL-1-beta and IL-6 responses to lethal E. coli septic shock were also significantly diminished by IL-1ra treatment (P < 0.05), whereas tumor necrosis factor-alpha (TNF-alpha) concentrations were unaffected. We conclude that an exaggerated systemic IL-1-beta response is characteristic of lethal E. coli septic shock, and contributes significantly to the hemodynamic and metabolic consequences of E. coli septic shock. IL-1ra can significantly attenuate the cytokine cascade and improve survival.