Unopposed interleukin-1 is necessary for increased plasma cytokine and eicosanoid levels to develop in severe sepsis

The purpose of the study was to identify the changes in plasma prostaglandin, leukotriene, and cytokine levels during clinical severe sepsis for which interleukin-1 was necessary.

Circulating prostaglandins, leukotrienes, and cytokines have been implicated as causative agents of systemic inflammation due to sepsis. However, interactions between interleukin-1 and the other cytokine and eicosanoid mediators of severe sepsis are not well-defined.

As part of two sequential multisite, prospective, randomized, double-blind, placebo-controlled clinical trials, 37 patients with severe sepsis received interleukin-1 receptor antagonist (IL-1ra) 100-mg bolus followed by 2 mg/kg per hour intravenously for 72 hours (n = 20) or placebo (n = 17). Plasma thromboxane B2 (TxB2), prostaglandin 6-keto-F1alpha (PGI), leukotriene B4 (LTB4), leukotriene C4D4E4 (LTC4D4E4), interleukin-1 beta (IL-1), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-alpha) were measured by enzyme-linked immunosorbent assay before study drug infusion (baseline) and at 24, 48, and 72 hours after the beginning of the study drug infusion.

Differences between placebo and IL-1ra for plasma LTB4 were not significant, but only IL-1ra LTB4 increased from baseline. Plasma TxB2, PGI, LTC4D4E4, TNF, and IL-6, expressed as % baseline, decreased significantly in patients receiving IL-1ra compared with the placebo group (p < 0.05), whereas plasma IL-1 increased significantly.

Interleukin-1 may be a necessary mediator of increased circulating PGI, TxB2, LTC4D4E4, TNF, and IL-6 levels in patients with severe sepsis. Plasma IL-1 and LTB4 are increased with infusion of IL-1 receptor antagonist. The clinical significance of IL-1 in modifying circulating eicosanoid and cytokine concentrations in clinical sepsis is not clear from the data.