Lipopolysaccharide induced synthesis of CD14 proteins and its gene expression in hepatocytes during endotoxemia.

AIM: To observe synthesis of CD14 protein and expression of CD14 mRNA in hepatic tissue and hepatocytes of rats during endotoxemia.
METHODS: The endotoxemia model of Wistar rat was established by injection of a dose of lipopolysaccharide (LPS) (5mg x kg(-1), Escherichia coli O111:B4) via the tail vein, then the rats were sacrificed after 3, 6, 12 and 24 h in batches respectively. Hepatocytes were isolated from normal and LPS-injected rats by in situ collagenase perfusion technique and were collected to measure the expression of CD14 mRNA and synthesis of CD14 protein by reverse transcript-polymerase chain reaction (RT-PCR) or Western blot analysis. The binding of fluorescein isothiocyanate (FITC)-CD14 polyclonal antibody to isolated hepatocytes was also assessed by flow cytometric analysis (FCM).
RESULTS: In the rats with endotoxemia, the expressions of CD14 mRNA in hepatic tissue and isolated hepatocytes were stronger at 3, 6, and 12 h than that in control rats (3.48+/-0.15, 5.89+/-0.62, 4.33+/-0.18, vs 1.35+/-0.14 in hepatic tissue, P<0.01; 4.12+/-0.17, 6.24+/-0.64, 4.35+/-0.18, vs 1.87+/-0.15 in hepatocytoes, P<0.01). The synthesis of CD14 protein in hepatic tissue and isolated hepatocytes increases also obviously in 6 and 12 h when compared to that in control rats (13.27+/-1.27, 17.32+/-1.35, 11.42+/-1.20, vs 7.34+/-0.72 in hepatic tissue, P<0.01; 14.68+/-1.30, 17.95+/-1.34,11.65+/-1.19, vs 7.91+/-0.70 in hepatocytes, P<0.01). FCM showed that mean fluorescence intensity (MFI) and numbers of FITC-CD14 positive cells in the rats with endotoxemia increased obviously at 3,6,12 and 24h when compared with normal control group (43.4%, 70.2%, 91.4%, 32.6% vs 4.5%, P<0.01).
CONCLUSION: LPS can markedly promote the synthesis of CD14 protein and up-regulate the expression of CD14 mRNA in isolated hepatocytes and hepatic tissue. Liver might be a main source for soluble CD14 production during endotoxemia.