CD14-lipopolysaccharide receptor activity in hepatic macrophages after cholestatic liver injury

Background. Increased septic complications and altered cytokine responses to bacterial endotoxins are lethal consequences of chronic liver disease. Kupffer cells (HMΦ) control the clearance of lipopolysaccharide (LPS) and subsequent cytokine responses. The purpose of this study is to determine the phenotype and function of HMΦ after cholestatic liver injury. Methods. Male Sprague-Dawley rats underwent 4 days of common bile duct division and ligation or sham laparotomy. HMΦ were isolated by collagenase-pronase perfusion and purified by centrifugal elutriation. Results. Indirect immunofluorescence and Western blot analysis with monolonal antibodies OX42 and ED9 showed that HMΦ from cholestatic rats expressed MAC-1 (CD 11b) and the LPS receptor CD14, respectively. HMΦ from sham animals were negative for CD14 and CD11b by use of immunofluorescence; however, Western blot detected low levels of CD14 in controls. Functional analysis for tumor necrosis factor-α release after LPS stimulation showed that HMΦ isolated from cholestatic livers exhibited serum (normal rat serum) dependent stimulation (1 ng/ml LPS+1% normal rat serum; n=12; p<0.05 at 8 hours, t test) consistent with the presence of CD14 on their cell surface. Conclusions. This study shows that HMΦ isolated after common bile duct division and ligation are phenotypically and functionally different from normal HMΦ. The appearance of serum-dependent LPS responses within the injured liver may play an important role in the immunologic alterations associated with hepatic disease.