The role of intestinal endotoxin in liver injury: a long and evolving history

From the mid-1950s, it was observed that liver injury by a variety of toxins greatly sensitized the host to the effects of administered lipopolysaccharide. In the nutritional cirrhosis of choline deficiency, and in acute toxic injury as well, the need for the presence of enteric endotoxin was demonstrated. The universality of this association was striking for almost all agents associated with liver injury. In addition, the presence of endotoxemia in human liver disease was documented in the 1970s, when the hypothesis was first proposed, and correlated with the severity of the disease. Despite imposing evidence of the critical role of enteric endotoxin in liver injury, it did not excite much interest in investigators until the 1980s. With the ability to study effects of alcohol in newer delivery systems, and an increased understanding of the role of Kupffer cells in the process, the original hypothesis has been accepted. This historical review details the progress of this novel concept of disease initiation and suggests future directions to bring potential therapies to the bedside.