Intratracheal Administration of Endotoxin and Cytokines : VII. The Soluble Interleukin-1 Receptor and the Soluble Tumor Necrosis Factor Receptor II (p80) Inhibit Acute Inflammation

Abstract

Intratracheal administration of endotoxin (LPS) causes acute neutrophilic inflammation via induction of pulmonary tumor necrosis factor [alpha] (TNF) and interleukin-1 (IL-1) expression. In the present study, the anti-inflammatory activity of soluble IL-1 receptor (sIL-1r) and soluble TNF receptor p80 (sTNFr-p80) in LPS-induced acute pulmonary inflammation was investigated. The sIL-1r coinjected intratracheally with LPS in rats significantly inhibits neutrophilic exudation into bronchoalveolar lavage (BAL) fluid by 47% after 6 hr compared to injection of LPS alone. TNF and IL-6 in the same BAL fluids were both lowered by approximately 50% after intratracheal coinjection of sIL-1r and LPS as compared to LPS alone. In the same model, the sTNFr-p80 inhibited acute inflammation. Paradoxically, TNF levels in BAL fluids were generally elevated after the intratracheal coinjectiun of LPS and monomeric sTNFr-p80 compared to injection of LPS injection alone. The combined anti-inflammatory effect of sIL-1r and sTNFr-p80 at the maximally effective individual doses is not significantly greater than the effect of either soluble receptor alone.