Hepatic macrophages promote the neutrophil-dependent resolution of fibrosis in repairing cholestatic rat livers

Background Cholestatic liver injury from extrahepatic biliary obstruction is well characterized by inflammatory and fibrogenic mechanisms. Little is known, however, about mechanisms required to reverse injury and effect liver repair. We sought to determine the cellular and molecular requirements for...

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Published in:Surgery 2008-05, Vol.143 (5), p.667-678
Main Authors: Harty, Mark W., PhD, Papa, Elaine F., BS, Huddleston, Hannah M., MD, Young, Ezekiel, BS, Nazareth, Samantha, BS, Riley, Charles A, Ramm, Grant A., PhD, Gregory, Stephen H., PhD, Tracy, Thomas F., MD
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Chemokine CXCL1 - metabolism
Cholestasis, Extrahepatic - complications
Cholestasis, Extrahepatic - immunology
Gene Expression
General aspects
Liver - immunology
Liver - metabolism
Liver Cirrhosis - etiology
Liver Cirrhosis - immunology
Liver Cirrhosis - metabolism
Liver Regeneration - immunology
Liver Regeneration - physiology
Macrophages - physiology
Male
Medical sciences
Neutrophils - physiology
Rats
Rats, Sprague-Dawley
Surgery
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Summary:Background Cholestatic liver injury from extrahepatic biliary obstruction is well characterized by inflammatory and fibrogenic mechanisms. Little is known, however, about mechanisms required to reverse injury and effect liver repair. We sought to determine the cellular and molecular requirements for repair after biliary decompression, focusing on the role of hepatic macrophages in regulating inflammation and matrix resolution. Methods Male Sprague-Dawley rats underwent bile duct obstruction for 7 days followed by ductular decompression. Rats were treated with gadolinium chloride (GdCl3 ) to deplete the macrophage populations 24 or 48 hours before decompression. Liver tissue obtained at the time of decompression or after 2 days of repair was processed for morphometric analysis, immunohistochemistry, quantitative RT-PCR and in situ hybridization. Results GdCl3 treatment for either 24 or 48 hours before decompression reduced the numbers of ED2+ Kupffer cells and ED1+ inflammatory macrophages in obstructed livers; only 48 hours of pretreatment, however, reduced the neutrophil counts. Furthermore, 48-hour GdCl3 pretreatment blocked matrix degradation. Quantitative polymerase chain reaction demonstrated decreased cytokine-induced neutrophil chemoattractant-1 (CINC-1; CXCL1) and intercellular adhesion molecule-1 mRNA expression after GdCl3 treatment and the elimination of hepatic macrophages. Immunohistochemistry and in situ hybridization revealed that neutrophils and CINC-1 mRNA localize within regions of fibrotic activity during both injury and repair. Conclusion We conclude that the macrophage population is not directly involved in fibrotic liver repair. Rather, hepatic macrophages regulate the influx of neutrophils, which may play a direct role in matrix degradation.
ISSN:0039-6060
1532-7361
DOI:10.1016/j.surg.2008.01.008