Neutrophil-Hepatic Stellate Cell Interactions Promote Fibrosis inExperimental Steatohepatitis.

Zhou Zhou,Natalie J Torok,Yan Cai,Zoltan V Varga,Ming-Jiang Xu,Pal Pacher,George Kunos,Bin Gao,Wei Wang,Joy X Jiang,Dechun Feng

doi:10.1016/j.jcmgh.2018.01.003

Abstract

Background & AimsHepatic infiltration of neutrophils is a hallmark of steatohepatitis; however, the role of neutrophils in the progression of steatohepatitis remains unknown.MethodsA clinically relevant mouse model of steatohepatitis induced by high-fat diet (HFD) plus binge ethanol feeding was used. Liver fibrosis was examined. In vitro cell culture was used to analyze the interaction of hepatic stellate cells (HSCs) and neutrophils.ResultsHFD plus one binge ethanol (HFD+1B) feeding induced significant hepatic neutrophil infiltration, liver injury, and fibrosis. HFD plus multiple binges of ethanol (HFD+mB) caused more pronounced liver fibrosis. Microarray analyses showed that the most highly activated signaling pathway in this HFD+1B model was related to liver fibrosis and HSC activation. Blockade of chemokine (C-X-C motif) ligand 1 or intercellular adhesion molecule-1 expression reduced hepatic neutrophil infiltration and ameliorated liver injury and fibrosis. Disruption of the p47phox gene (also called neutrophil cytosolic factor 1), a critical component of reactive oxygen species producing nicotinamide adenine dinucleotide phosphate-oxidase in neutrophils, diminished HFD+1B–induced liver injury and fibrosis. Co-culture of HSCs with neutrophils, but not with neutrophil apoptotic bodies, induced HSC activation and prolonged neutrophil survival. Mechanistic studies showed that activated HSCs produce granulocyte-macrophage colony-stimulating factor and interleukin-15 to prolong the survival of neutrophils, which may serve as a positive forward loop to promote liver damage and fibrosis.ConclusionsThe current data from a mouse model of HFD plus binge ethanol feeding suggest that obesity and binge drinking synergize to promote liver fibrosis, which is partially mediated via the interaction of neutrophils and HSCs. Microarray data in this article have been uploaded to NCBI’s Gene Expression Omnibus (GEO accession number: GSE98153).

Highlights

BACKGROUND & AIMSHepatic infiltration of neutrophils is a hallmark of steatohepatitis; the role of neutrophils in the progression of steatohepatitis remains unknown
Mechanistic studies showed that activated hepatic stellate cell (HSC) produce granulocyte-macrophage colony-stimulating factor and interleukin-15 to prolong the survival of neutrophils, which may serve as a positive forward loop to promote liver damage and fibrosis
The current data from a mouse model of high-fat diet (HFD) plus binge ethanol feeding suggest that obesity and binge drinking synergize to promote liver fibrosis, which is partially mediated via the interaction of neutrophils and HSCs

Summary

Methods

A clinically relevant mouse model of steatohepatitis induced by high-fat diet (HFD) plus binge ethanol feeding was used. Abbreviations used in this paper: ALT, alanine aminotransferase; AST, aspartate aminotransferase; cDNA, complementary DNA; Csf, colonystimulating factor gene; CXCL1, chemokine (C-X-C motif) ligand 1; FBS, fetal bovine serum; 4-HNE, 4-hydroxynonenal; G-CSF, granulocyte colony-stimulating factor; GM-CSF, granulocyte-macrophage colonystimulating factor; IL, interleukin; HFD, high-fat diet; HFDDmB, highfat diet plus multiple binges; HFDD1B, high-fat diet feeding plus 1 binge of ethanol; HSC, hepatic stellate cell; ICAM-1, intercellular adhesion molecule-1; KO, knockout; MPO, myeloperoxidase; mRNA, messenger RNA; PCR, polymerase chain reaction; RT-PCR, reverse-transcription polymerase chain reaction; ROS, reactive oxygen species; TUNEL, terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick-end labeling; WT, wild-type. Cxcl1-/- mice on a C57BL/6 background were kind gifts from Dr Sergio Lira (Mount Sinai, NY) and were further backcrossed into a C57BL/6J background for 5 more generations at the National Institute on Alcohol Abuse and Alcoholism animal facility, with C57BL/6J mice being used as wild-type (WT) controls.

Results

Discussion

Conclusion