Objective: To investigate the role of endotoxin receptor expression in the activation of hepatic stellate cells (HSCs).
Methods: HSCs were isolated from normal rats and the expression of endotoxin receptors on quiet HSCs and in vitro activated HSCs was determined using RT-PCR and immunocytochemical staining methods. A rat model of liver fibrosis and cirrhosis was established. The expressions of CD14 and alpha-SMA in liver tissues were detected by immunohistochemical staining.
Results: Freshly isolated HSCs had a low level of CD14 mRNA expression and no expression of TLR4 mRNA was detected. The in vitro activated HSCs had increased expressions of CD14 mRNA and TLR4 mRNA and LPS up-regulated the expression of endotoxin receptors. Immunocytochemical staining showed cytoplasmic and nucleolus staining for CD14 in the cultured HSCs. LPS played a further role on CD14 protein expression. In the development of liver fibrosis, the number of CD14-positive cells in the livers was increased and these cells were distributed along the sinusoids. In the later stage of liver fibrosis, the CD14-positive cells were gathered in the fibrotic septae, which also contained alpha-SMA positive cells.
Conclusion: The activated HSCs expressed endotoxin receptors. The endotoxin receptors may be involved in the role in which HSCs played in the inflammatory process and liver fibrosis development.