Evidence that arachidonic acid derived from neutrophils and prostaglandin E2 are associated with the induction of acute lung inflammation by lipopolysaccharide of Escherichia coli

Objective: The involvement of arachidonic acid (AA) and PGE(2) during the E. coli lipopolysaccharide (LPS)-induced acute lung injury was investigated. Material: Adult male Wistar rats were used. For in vitro studies, rat neutrophils, bronchoalveolar lavage (BAL) fluid, and lung vascular endothelium were used, as described below. Treatment: Rats were given an intratracheal injection of LPS (750 mug). Methods: Total and differential cell counts in BAL fluid; enzyme-linked immunoassay (ELISA) analyses of TNF-alpha, IL-1beta, LTB4 and PGE(2) in BAL, and immunohistochemical detection of ICAM-I on lung vascular endothelium were performed six h after LPS challenge. Fatty acid composition of blood neutrophils and plasma was analyzed by HPLC. Results: Rats instilled with LPS presented a sixty three-fold increase in the number of neutrophils in BAL (from 0.5 x 10(6) to 31.5 x 10(6) cells), accompanied by increased levels of TNF-alpha and IL-1beta (p < 0.001), and a three-fold increase in ICAM-1 expression on vascular endothelium. The content of AA in blood neutrophils was reduced by 50%, whereas the level of PGE(2) in BAL was increased by 3.5 fold, without changes in the levels of LTB4. Conclusions: These findings suggest that AA and PGE(2) are associated with LPS challenge.