EXPERIMENTAL BILIARY FIBROSIS CORRELATES WITH INCREASED NUMBERS OF FAT-STORING AND KUPFFER CELLS, AND PORTAL ENDOTOXEMIA

In the present study, we have investigated the correlation between hep atic fibrosis in rats subjected to bile duct ligation, the numbers of Kupffer and fat-storing cells, and the level of endotoxin in both the portal and systemic circulation. The extent of hepatic fibrosis was me asured by morphometry. Kupffer cells were identified by indirect immun operoxidase staining using ED-2 anti-macrophage antibody. Fat-storing cells were stained with DE-B-5 anti-desmin antibody. Endotoxin levels were determined by the Limulus Lysate test. Following bile duct ligati on, connective tissue septa rapidly developed in periportal areas. Aft er 1 week, the volume density of connective tissue had increased from 0.6+/-0.1% in control animals to 3.8+/-1.1%. After 2 weeks, this volum e increased to 19.9+/-1.3%, and after 3 weeks to 34.3+/-2.7%. The numb er of periportal fat-storing cells increased 2.8-fold during the first 2 weeks, whereas pericentral fat-storing cells increased only 1.7-fol d. After 2 weeks, no further increase was observed. During the first w eek of bile duct ligation, the number of Kupffer cells increased nearl y two-fold. Thereafter, no further increase was detected. In control r ats, only two of ten rats showed low amounts of endotoxin in the porta l blood. Portal endotoxemia increased with time after bile duct ligati on. After 3 weeks, all rats were positive. The measured endotoxin leve ls were approximately 7 times higher than in control rats. We conclude that the development of fibrosis secondary to experimental bile duct ligation is accompanied by portal endotoxemia, and increases in the nu mbers of Kupffer and periportal fat-storing cells. We found a signific ant correlation between portal endotoxemia, the number of Kupffer and fat-storing cells, and the extent of fibrous septa, supporting the vie w that high endotoxemia levels coincide with Kupffer cell activation a nd fibrogenesis.