Modulation of Hepatic Amyloid Precursor Protein and Lipoprotein Receptor-Related Protein 1 by Chronic Alcohol Intake: Potential Link Between Liver Steatosis and Amyloid-β

Authors

Jerome Garcia, University of La Verne
Rudy Chang, Chapman University
Ross A. Steinberg, Keck Graduate Institute
Aldo Arce, Keck Graduate Institute
Joshua Yang, Chapman University
Peter Van Der Eb, Keck Graduate Institute
Tamara Abdullah, Chapman University
Devaraj V. Chandrashekar, Chapman University
Syndey M. Eck, Keck Graduate Institute
Pablo Meza, Keck Graduate Institute
Zhang-Xu Liu, University of Southern California
Enrique Cadenas, University of Southern California
David H. Cribbs, University of California, Irvine
Neil Kaplowitz, University of Southern California
Rachita K. Sumbria, Chapman UniversityFollow
Derick Han, Keck Graduate InstituteFollow

Document Type

Article

Publication Date

9-15-2022

Abstract

Heavy alcohol consumption is a known risk factor for various forms of dementia and the development of Alzheimer’s disease (AD). In this work, we investigated how intragastric alcohol feeding may alter the liver-to-brain axis to induce and/or promote AD pathology. Four weeks of intragastric alcohol feeding to mice, which causes significant fatty liver (steatosis) and liver injury, caused no changes in AD pathology markers in the brain [amyloid precursor protein (APP), presenilin], except for a decrease in microglial cell number in the cortex of the brain. Interestingly, the decline in microglial numbers correlated with serum alanine transaminase (ALT) levels, suggesting a potential link between liver injury and microglial loss in the brain. Intragastric alcohol feeding significantly affected two hepatic proteins important in amyloid-beta (Aβ) processing by the liver: 1) alcohol feeding downregulated lipoprotein receptor-related protein 1 (LRP1, ∼46%), the major receptor in the liver that removes Aβ from blood and peripheral organs, and 2) alcohol significantly upregulated APP (∼2-fold), a potentially important source of Aβ in the periphery and brain. The decrease in hepatic LRP1 and increase in hepatic APP likely switches the liver from being a remover or low producer of Aβ to an important source of Aβ in the periphery, which can impact the brain. The downregulation of LRP1 and upregulation of APP in the liver was observed in the first week of intragastric alcohol feeding, and also occurred in other alcohol feeding models (NIAAA binge alcohol model and intragastric alcohol feeding to rats). Modulation of hepatic LRP1 and APP does not seem alcohol-specific, as ob/ob mice with significant steatosis also had declines in LRP1 and increases in APP expression in the liver. These findings suggest that liver steatosis rather than alcohol-induced liver injury is likely responsible for regulation of hepatic LRP1 and APP. Both obesity and alcohol intake have been linked to AD and our data suggests that liver steatosis associated with these two conditions modulates hepatic LRP1 and APP to disrupt Aβ processing by the liver to promote AD.

Comments

This article was originally published in Frontiers in Physiology, volume 13, in 2022. https://doi.org/10.3389/fphys.2022.930402

Recommended Citation

Garcia J, Chang R, Steinberg RA, Arce A, Yang J, Van Der Eb P, Abdullah T, Chandrashekar DV, Eck SM, Meza P, Liu Z-X, Cadenas E, Cribbs DH, Kaplowitz N, Sumbria RK and Han D (2022), Modulation of hepatic amyloid precursor protein and lipoprotein receptor-related protein 1 by chronic alcohol intake: Potential link between liver steatosis and amyloid-β. Front. Physiol. 13:930402. https://doi.org/10.3389/fphys.2022.930402

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This work is licensed under a Creative Commons Attribution 4.0 License.