Function of Macrophage Subsets in Alcohol-Associated Liver Disease

Liver macrophages include both tissue resident Kupffer cells and more transient infiltrating macrophages. Collectively, they are important in maintaining homeostatic liver function under normal conditions and clearing pathogens and responding to tissue injury under disease states. We have been using a combination of single cell RNA sequencing and diphtheria-toxin mediated targeted cell ablation approaches to explore the heterogeneity, embryological origins, and functions of specific subsets of Kupffer cells and infiltrating macrophages. Our work has shown that upon exposure to alcohol, embryonic Kupffer cells are progressively replaced by at least 2 different populations of monocyte-derived replacement Kupffer cells which express both pro-inflammatory as well as anti-fibrotic gene signatures. The original, embryonic Kupffer cells are important in maintaining differentiated hepatocyte function in the alcohol-exposed liver. Sudden ablation of mature Kupffer cells results in loss of hepatocyte function and liver failure closely resembling the human phenomenon of “Alcoholic Hepatitis.”

Ongoing work in the lab seeks to understand the signals transmitted from Kupffer cells to hepatocytes that are responsible for maintaining hepatocyte differentiation. Our goals are to harness these mechanisms to treat liver failure in advanced alcohol-associated liver disease.

Resolution of liver injury in animal models of alcohol-associated liver disease

Liver fibrosis and dysfunction frequently persist in patients with alcohol-associated liver disease even after they have stopped drinking. Improving the outcome for patients after alcohol abstinence is an important objective of our research. In collaboration with Dr. Irina Tikhanovich, our lab has been examining the process by which fibrosis resolves or fails to resolve upon stopping alcohol. Using mouse models and comparing liver histology before and after alcohol cessation, we have found that alcohol-associated fibrosis frequently increases 4 weeks after alcohol cessation. Ongoing research has been examining the roles of macrophage subsets and epigenetic modifiers in determining how liver fibrosis changes after alcohol cessation.

Multicellular in vitro models of Liver Disease

In collaboration with Dr. Salman Khetani, University of Illinois, Chicago, we are using multicellular micropatterned co-cultures and 3D liver microtissues containing primary mouse hepatocytes, liver endothelial cells, hepatic stellate cells and Kupffer cells to investigate the role of specific cells and cell subtype in the pathogenesis of alcohol associated liver disease. These bioengineered systems will be utilized to elucidate the direct effects of alcohol on multiple liver cell types, the extent to which the alcohol-associated liver disease phenotype can be maintained in culture, and the effects of liver nonparenchymal cells on hepatocellular functions in alcohol associated liver disease. Our platform could serve as a resource to other investigators, and could be coupled with other tissue types within microfluidic systems to elucidate the role of organ-organ crosstalk in progressive ALD.

References:

• Ghosh, P., Sasaki, K., Pulido Ruiz, I. A., King, K. E., Weinman, S. A., & Wozniak, A. L. (2023). Inflammatory macrophage to hepatocyte signals can be prevented by extracellular vesicle reprogramming. Journal of cell science, jcs.260691. Advance online publication. https://doi.org/10.1242/jcs.260691 
• Elias, G., Schonfeld, M., Saleh, S., Parrish, M., Barmanova, M., Weinman, S. A., & Tikhanovich, I. (2023). Sepsis induced endothelial dysfunction drives acute-on-chronic liver failure via Angiopoietin-2-HGF-C/EBPβ pathway. Hepatology (Baltimore, Md.), 10.1097/HEP.0000000000000354. Advance online publication. https://doi.org/10.1097/HEP.0000000000000354
• Schonfeld, M., O'Neil, M., Villar, M. T., Artigues, A., Averilla, J., Gunewardena, S., Weinman, S. A., & Tikhanovich, I. (2021). A Western diet with alcohol in drinking water recapitulates features of alcohol-associated liver disease in mice. Alcoholism, clinical and experimental research, 45(10), 1980–1993. https://doi.org/10.1111/acer.14700 
• Li, Z., & Weinman, S. A. (2018). Regulation of Hepatic Inflammation via Macrophage Cell Death. Seminars in liver disease, 38(4), 340–350. https://doi.org/10.1055/s-0038-1670674 
• Li, Z., Zhao, J., Zhang, S., & Weinman, S. A. (2018). FOXO3-dependent apoptosis limits alcohol-induced liver inflammation by promoting infiltrating macrophage differentiation. Cell death discovery, 4, 16. https://doi.org/10.1038/s41420-017-0020-7