Objective: To explore the role of endotoxin in the pathogenesis of nonalcoholic steatohepatitis (NASH).
Methods: Rat models of NASH were established by giving a fat-riched diet. These rats were sacrificed at the 4th, 8th, 12th, 16th and 24th weeks during the study. The other rats fed with normal diet were taken as normal controls at the same stage during the study. The blood of abdominal aorta was obtained and the levels of serum endotoxin, tumor necrosis factor-alpha (TNF-a), and interleukin-1 beta (IL-1 b) were measured. The expression of CD(14) and lysozyme in rats' livers were detected by immunohistochemistry.
Results: Rat models of NASH with liver fibrosis were established successfully. The levels of endotoxin in aorta blood of NASH rats increased significantly at the 24th week (0.23 EU/L 0.06 EU/L vs 0.15 EU/L 0.03 EU/L, t>2.179, p <0.05) while the expression of CD(14) increased from the 4th week, and the Kupffer cells expressing lysozyme were activated, then kept increasing activation through the study. In NASH rats, the levels of serum TNF-a increased from the 8th week (26.39 pg/ml 24.21 pg/ml vs 9.82 pg/ml 9.29 pg/ml, t>2.145, p < 0.05) and serum IL-1beta increased from the 16th week (23.76 pg/ml 21.81 pg/ml vs 6.25 pg/ml 2.98 pg/ml, t>2.145, p<0.05).
Conclusion: Liver injury results from endotoxin existing in NASH rats which may play an important role in the pathogenesis of NASH by activating Kupffer cells and inducing the production of cytokines, such as TNF-a.