The Hepatic “Matrisome” Responds Dynamically to Stress: Novel Characterization of the ECM Proteome

Background. There are no therapies to halt or reverse chronic liver disease (e.g., ALD), which follows a common natural history leading to end-stage liver disease and hepatocellular carcinoma (HCC). Outside the context of fibrosis, the nature and impact of the dynamic responses of the hepatic ECM proteome (i.e., matrisome) to stress are poorly understood. The goal of this work was to develop a proteomic method to characterize the hepatic matrisome and compare the impact of ethanol and lipopolysaccharide (LPS) on this compartment. Methods. Mice were fed ethanol-containing or isocaloric control diet for 6 weeks and injected with LPS or a vehicle 24 hours prior to sacrifice. Liver sections were processed in a series of increasingly rigorous extraction buffers to separate proteins by age and crosslinking. Extracted proteins were identified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). ECM proteins were mined, categorized by primary function and compared between experimental groups. Immunoblotting was performed for fibrin and osteopontin, proteins previously found to be significant in ALD-associated ECM remodeling. Results. The extraction yielded distinct pools of ECM proteins identifiable by LC-MS/MS. The matrisome responded dynamically to stress. Ethanol caused a dramatic ~30% increase in the number of matrisome proteins; LPS produced a similar response. The enhancement of LPS-induced liver damage by ethanol preexposure demonstrated unique protein changes. Conclusions. These results suggest that this approach can document qualitative changes to the ECM proteome (i.e., presence and absence). Future work will investigate quantitative matrisome changes. Supported by NIH/NCI (5R25CA134283-03) and NIH/NIAAA (1R01AA021978-01)