Neutrophil depletion blocks early collagen degradation in repairing cholestatic rat livers.
Biliary obstruction results in a well-characterized cholestatic inflammatory and fibrogenic process; however, the mechanisms and potential for liver repair remain unclear. We previously demonstrated that Kupffer cell depletion reduces polymorphonuclear cell (neutrophil) (PMN) and matrix metalloproteinase (MMP)8 levels in repairing liver. We therefore hypothesized that PMN-dependent MMP activity is essential for successful repair. Male Sprague-Dawley rats received reversible biliary obstruction for 7 days, and the rat PMN-specific antibody RP3 was administered 2 days before biliary decompression (repair) and continued daily until necropsy, when liver underwent morphometric analysis, immunohistochemistry, quantitative RT-PCR, and in situ zymography. We found that RP3 treatment did not reduce Kupffer cell or monocyte number but significantly reduced PMN number at the time of decompression and 2 days after repair. RP3 treatment also blocked resorption of type I collagen. In addition, biliary obstruction resulted in increased expression of MMP3, MMP8, and tissue inhibitor of metalloproteinase 1. Two days after biliary decompression, both MMP3 and tissue inhibitor of metalloproteinase 1 expression declined toward sham levels, whereas MMP8 expression remained elevated and was identified in bile duct epithelial cells by immunohistochemistry. PMN depletion did not alter the hepatic expression of these genes. Conversely, collagen-based in situ zymography demonstrated markedly diminished collagenase activity following PMN depletion. We conclude that PMNs are essential for collagenase activity and collagen resorption during liver repair, and speculate that PMN-derived MMP8 or PMN-mediated activation of intrinsic hepatic MMPs are responsible for successful liver repair.
Harty
Mark W
MW
Department of Surgery, The Warren Alpert Medical School of Brown University, Hasbro Children's Hospital, Room 147, 593 Eddy Street, Providence, RI 02903, USA.
Muratore
Christopher S
CS
Papa
Elaine F
EF
Gart
Michael S
MS
Ramm
Grant A
GA
Gregory
Stephen H
SH
Tracy
Thomas F
TF
D000818:Animals; D001772:Blood Cell Count; D002779:Cholestasis / Q000201:enzymology / Q000235:genetics / Q000473:pathology*; D003094:Collagen / Q000378:metabolism*; D018093:Gelatinases / Q000378:metabolism; D005786:Gene Expression Regulation; D007150:Immunohistochemistry; D007249:Inflammation / Q000473:pathology; D047589:Leukocyte Reduction Procedures; D008099:Liver / Q000201:enzymology / Q000473:pathology*; D008103:Liver Cirrhosis / Q000473:pathology; D008297:Male; D020784:Matrix Metalloproteinase 8 / Q000378:metabolism; D009504:Neutrophils / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014945:Wound Healing
D003094:Collagen; D018093:Gelatinases; D020784:Matrix Metalloproteinase 8