Background: Triglyceride-rich lipoproteins have been shown to bind bacterial endotoxin and inhibit its activity in vitro and to protect animals from death when administered before a lethal injection of endotoxin. We now demonstrate that triglyceride-rich lipoproteins can neutralize the toxic effects of endotoxin already in circulation.
Methods: Rats were infused with a lethal dose of endotoxin, followed at various time intervals by an infusion of either mesenteric lymph containing nascent chylomicrons (1 gm chylomicron triglyceride/kg) or an equal volume of normal saline solution. Survival was measured at 48 hours. The experiment was then repeated, substituting the synthetic triglyceride-rich lipid emulsion (1 gm/kg) for chylomicrons. We also measured the clearance and tissue distribution of radioiodinated endotoxin in rats treated subsequently with chylomicrons or saline solution.
Results: Chylomicron infusions significantly improved survival when given up to 30 minutes after a lethal dose of endotoxin (p < 0.05). Chylomicrons accelerated endotoxin clearance from the blood and increased endotoxin uptake by the liver. The synthetic triglyceride-rich lipid emulsion significantly improved survival when given up to 15 minutes after a lethal dose of endotoxin (p < 0.05).
Conclusions: Triglyceride-rich lipoproteins and synthetic triglyceride-rich lipid emulsions significantly improve survival of rats when given after a lethal dose of endotoxin. Lipoprotein treatment accelerates endotoxin clearance to the liver, which may account for the observed protection. These data suggest a possible therapeutic role for triglyceride-rich lipoproteins or synthetic lipid emulsions in the treatment of the endotoxemia of gram-negative sepsis.