Abstract
Cholestasis is frequently related to endotoxemia and inflammatory response. Our previous investigation revealed a significant increase in plasma endotoxin and CD14 levels during biliary atresia. We therefore propose that lipopolysacharides (LPS) may stimulate CD14 production in liver cells and promote the removal of endotoxins. The aims of this study are to test the hypothesis that CD14 is upregulated by LPS and investigate the pathophysiological role of CD14 production during cholestasis. Using Western blotting, qRT-PCR, and promoter activity assay, we demonstrated that LPS was associated with a significant increase in CD14 and MD2 protein and mRNA expression and CD14 promoter activity in C9 rat hepatocytes but not in the HSC-T6 hepatic stellate cell line in vitro. To correlate CD14 expression and endotoxin sensitivity, in vivo biliary LPS administration was performed on rats two weeks after they were subjected to bile duct ligation (BDL) or a sham operation. CD14 expression and endotoxin levels were found to significantly increase after LPS administration in BDL rats. These returned to basal levels after 24 h. In contrast, although endotoxin levels were increased in sham-operated rats given LPS, no increase in CD14 expression was observed. However, mortality within 24 h was more frequent in the BDL animals than in the sham-operated group. In conclusion, cholestasis and LPS stimulation were here found to upregulate hepatic CD14 expression, which may have led to increased endotoxin sensitivity and host proinflammatory reactions, causing organ failure and death in BDL rats.
Highlights
Cholestasis, impairment of bile outflow, occurs in a wide variety of human liver diseases [1,2,3]
To evaluate TLR4, CD14, and MD2 protein expression in liver cells after LPS treatment, Western blot analysis was performed on protein from C9 rat hepatocytes and HSC-T6 cells stimulated with various concentrations of LPS
For HSC-T6 cells, CD14, and MD2 protein expression showed no significant fluctuations after 6 h or 24 h of LPS treatment (Figure 1B), and barely a trace of TLR4 was detected at any time
Summary
Cholestasis, impairment of bile outflow, occurs in a wide variety of human liver diseases [1,2,3]. Endotoxemia, which is a frequent complication of cholestasis, can be caused by a decrease in bile flow promoting bacterial translocation from the gut [4]. The liver is the major organ downstream of the gut and is responsible for LPS clearance by both parachymal cells (hepatocytes) and nonparachymal cells (hepatic stellate cells and Kupffer cells) [7]. Kupffer cells have been found to modulate LPS for rapid internalization within hepatocytes to clear through bile flow and prevent systemic distribution and widespread inflammatory reactions during endotoxemia [7,8]. LPS and bacterial clearance from the liver were found to be reduced in BDL compared with sham-operated animals through the impairment of phagocytic ability and an inability to kill intracellular bacteria in Kupffer cells [9,10,11]. The mechanisms underlying the impaired endotoxin clearance capacity of hepatocytes during cholesatasis are not clearly defined
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
