Obstruktive Cholestase führt zu einer P-Selektin-vermittelten Leukozyteninfiltration der Leber

Abstract

Background: Obstructive cholestasis induces an inflammatory reaction of the liver tissue with release of inflammatory mediators from Kupffer cells, resulting in hepatocellular damage. In the present study we investigated the role of leukocytes in this inflammatory reaction during the early phase of obstructive cholestasis. Materials and Methods: Obstructive cholestasis was induced in 20 C57BL/6 mice by ligation of the common bile duct. These mice were pretreated with phosphate-buffered saline (PBS; 0.2 ml i. v.; n = 8), P-selectin antibody (anti-P-selectin; 1.5 mg/kg i. v.; n = 6) or control antibody (control-IgG; 1.5 mg/kg i. v.; n = 6). Five additional sham-operated animals served as controls. After 6 hours, we analyzed in vivo leukocyte-endothelial cell interaction in liver venules as well as sinusoidal leukocyte trapping and perfusion failure by means of intravital fluorescence microscopy. In addition, liver injury was determined by measuring the serum levels of bilirubin, AST and ALT. Results: In all experimental groups ligation of the common bile duct resulted in the development of obstructive cholestasis after 6 hours with significantly elevated serum levels of bilirubin (PBS: 1.7 ± 0.2 mg/dl; control-IgG: 2.1 ± 0.2 mg/dl; anti-P-selectin: 1.8 ± 0.3 mg/dl; p < 0.05), when compared to sham-operated controls (0.5 ± 0.0 mg/dl). Intravital fluorescence microscopy of liver venules in the PBS and control-IgG group demonstrated that numbers of adherent (570 ± 106mm−2 and 621 ± 147 mm−2 vs sham 65 ± 35 mm−2) and rolling leukocytes (8.5 ± 1.0 min−1 and 8.2 ± 0.9 min−1 vs sham 3.1 ± 1.0 min−1) were increased. In addition, both groups exhibited an elevated number of trapped leukocytes in sinusoids and an increased sinusoidal perfusion failure (25 ± 4 % and 28 ± 5 % vs sham 3 ± 1 %; p < 0.05). Accordingly, serum AST (702 ± 134 U/l and 808 ± 146 U/l vs sham 75 ± 13 U/l) and ALT levels (330 ± 74 U/l and 396 ± 65 U/l vs sham 30 ± 4 U/l) indicated hepatocellular damage. Interestingly, treatment with the P-selectin antibody resulted in a significantly decreased leukocyte-endothelial cell interaction (adherent leukocytes: 116 ± 56 mm−2; rolling leukocytes: 3.9 ± 0.3 min−1; p < 0.05) and sinusoidal perfusion failure (6 ± 2 %; p < 0.05). Furthermore, serum levels of liver enzymes were reduced when compared to the control-IgG group (AST: 415 ± 31 U/l; ALT: 220 ± 27 U/l). Conclusion: The present study demonstrates that obstructive cholestasis induces P-selectin-mediated leukocyte infiltration of the liver resulting in hepatocellular damage. Thus, inhibition of leukocyte recruitment into the liver could represent a novel therapeutic approach to reduce cholestatic liver injury.