Effect of continuous infusion of lipid emulsions on endotoxin induced acute lung injury and mechanism in rats

Objectives To compare the effects of three kinds of lipid emulsions on IL-1β expression and alveolar epithelial cell apoptosis in LPS-induced acute lung injury(ALI) in rat.Methods One hundred young Sprague-Dawley rats were divided into control group,LPS group,Intra group(20% Intralipid),Clino group(20% Clinoleic) and Omega group(10% Omegaven).Each group was treated with normal saline or different lipid emulsions for seven days.The rats were intratracheally instilled with normal saline or LPS to establish the rat model of ALI 8 hours before sacrifice.The pathologic changes in lung tissue section were observed and the apoptosis index(AI) was measured.The expression level of IL-1β mRNA was determined by RT-PCR.Meanwhile the concentration of IL-1β in broncho-alveolar lavage fluid(BALF) was measured by enzyme-linked immunospecific assay(ELISA).Results The expression of IL-1β mRNA and the level of IL-1β in BALF in Intra group were significantly elevated as compared to Clino group and Omega group(both P0.005),but there was no significant difference(P0.005) between Clino group and Omega group.HE-stained lung tissues showed obvious infiltration of inflammatory cells and bleeding in all groups.The AI was lower in Clino group and Omega group than in LPS group and Intra group(both P0.005) and the difference was not significant between Clino group and Omega group(P0.005).Conclusions Clinoleic and Omegaven may relieve inflammation by down-regulating IL-1β and reduce the alveolar epithelial cell apoptosis in rats with acute lung injury.