Activation of receptor-independent fluid-phase pinocytosis promotes foamy monocyte formation in atherosclerotic mice

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death worldwide. Clinical and experimental data demonstrated that circulating monocytes internalize plasma lipoproteins and become lipid-laden foamy cells in hypercholesterolemic subjects. This study was designed to identify the...

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Main Authors: WonMo Ahn, Faith N. Burnett, Kamila Wojnar-Lason, Jaser Doja, Amritha Sreekumar, Pushpankur Ghoshal, Bhupesh Singla, Graydon Gonsalvez, Ryan A. Harris, Xiaoling Wang, Joseph M. Miano, Gábor Csányi
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Language:English
Published: Elsevier 2024-12-01
Series:Redox Biology
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Online Access:http://www.sciencedirect.com/science/article/pii/S2213231724004014
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author WonMo Ahn
Faith N. Burnett
Kamila Wojnar-Lason
Jaser Doja
Amritha Sreekumar
Pushpankur Ghoshal
Bhupesh Singla
Graydon Gonsalvez
Ryan A. Harris
Xiaoling Wang
Joseph M. Miano
Gábor Csányi
author_facet WonMo Ahn
Faith N. Burnett
Kamila Wojnar-Lason
Jaser Doja
Amritha Sreekumar
Pushpankur Ghoshal
Bhupesh Singla
Graydon Gonsalvez
Ryan A. Harris
Xiaoling Wang
Joseph M. Miano
Gábor Csányi
author_sort WonMo Ahn
collection DOAJ
description Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death worldwide. Clinical and experimental data demonstrated that circulating monocytes internalize plasma lipoproteins and become lipid-laden foamy cells in hypercholesterolemic subjects. This study was designed to identify the endocytic mechanisms responsible for foamy monocyte formation, perform functional and transcriptomic analysis of foamy and non-foamy monocytes relevant to ASCVD, and characterize specific monocyte subsets isolated from the circulation of normocholesterolemic controls and hypercholesterolemic patients. We hypothesized that activation of fluid-phase macropinocytosis contributes to foamy monocyte formation in vitro and in hypercholesterolemic mice in vivo. High resolution scanning electron microscopy (SEM) and quantification of FITC/TRITC-dextran internalization demonstrated macropinocytosis stimulation in human (THP-1) and wild type murine monocytes. Stimulation of macropinocytosis induced foamy monocyte formation in the presence of unmodified, native LDL (nLDL) and oxidized LDL (ox-LDL) in vitro. Genetic blockade of macropinocytosis (LysMCre+ Nhe1f/f) inhibited foamy monocyte formation in hypercholesterolemic mice in vivo and attenuated monocyte adhesion to atherosclerotic aortas ex vivo. Mechanistic studies identified NADPH oxidase 2 (Nox2)-derived superoxide anion (O2⋅−) as an important downstream signaling molecule stimulating macropinocytosis in monocytes. qRT-PCR identified CD36 as a major scavenger receptor that increases in response to lipid loading in monocytes and deletion of CD36 (Cd36−/−) inhibited foamy monocyte formation in hypercholesterolemic mice. Bulk RNA-sequencing characterized transcriptional differences between non-foamy and foamy monocytes versus macrophages. Finally, flow cytometry analysis of CD14 and CD16 expression demonstrated a significant increase in intermediate monocytes in hypercholesterolemic patients compared to normocholesterolemic controls. These results provide novel insights into the mechanisms of foamy monocyte formation and potentially identify new therapeutic targets for the treatment of atherosclerosis.
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spelling doaj-art-629bc4cc1c894b0b960b7df25d1a1df52024-12-08T06:10:05ZengElsevierRedox Biology2213-23172024-12-0178103423Activation of receptor-independent fluid-phase pinocytosis promotes foamy monocyte formation in atherosclerotic miceWonMo Ahn0Faith N. Burnett1Kamila Wojnar-Lason2Jaser Doja3Amritha Sreekumar4Pushpankur Ghoshal5Bhupesh Singla6Graydon Gonsalvez7Ryan A. Harris8Xiaoling Wang9Joseph M. Miano10Gábor Csányi11Vascular Biology Center, Augusta University, Medical College of Georgia, Augusta, GA, 30912, USAVascular Biology Center, Augusta University, Medical College of Georgia, Augusta, GA, 30912, USAVascular Biology Center, Augusta University, Medical College of Georgia, Augusta, GA, 30912, USAVascular Biology Center, Augusta University, Medical College of Georgia, Augusta, GA, 30912, USAVascular Biology Center, Augusta University, Medical College of Georgia, Augusta, GA, 30912, USAVascular Biology Center, Augusta University, Medical College of Georgia, Augusta, GA, 30912, USAVascular Biology Center, Augusta University, Medical College of Georgia, Augusta, GA, 30912, USADepartment of Cellular Biology & Anatomy, Augusta University, Medical College of Georgia, Augusta, GA, 30912, USAGeorgia Prevention Institute, Augusta University, Medical College of Georgia, Augusta, GA, 30912, USAGeorgia Prevention Institute, Augusta University, Medical College of Georgia, Augusta, GA, 30912, USAVascular Biology Center, Augusta University, Medical College of Georgia, Augusta, GA, 30912, USAVascular Biology Center, Augusta University, Medical College of Georgia, Augusta, GA, 30912, USA; Department of Pharmacology and Toxicology, Augusta University, Medical College of Georgia, Augusta, GA, 30912, USA; Corresponding author. CB3213A, 1459 Laney Walker Blvd., Augusta University, Medical College of Georgia, Augusta, GA, 30912, USA.Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death worldwide. Clinical and experimental data demonstrated that circulating monocytes internalize plasma lipoproteins and become lipid-laden foamy cells in hypercholesterolemic subjects. This study was designed to identify the endocytic mechanisms responsible for foamy monocyte formation, perform functional and transcriptomic analysis of foamy and non-foamy monocytes relevant to ASCVD, and characterize specific monocyte subsets isolated from the circulation of normocholesterolemic controls and hypercholesterolemic patients. We hypothesized that activation of fluid-phase macropinocytosis contributes to foamy monocyte formation in vitro and in hypercholesterolemic mice in vivo. High resolution scanning electron microscopy (SEM) and quantification of FITC/TRITC-dextran internalization demonstrated macropinocytosis stimulation in human (THP-1) and wild type murine monocytes. Stimulation of macropinocytosis induced foamy monocyte formation in the presence of unmodified, native LDL (nLDL) and oxidized LDL (ox-LDL) in vitro. Genetic blockade of macropinocytosis (LysMCre+ Nhe1f/f) inhibited foamy monocyte formation in hypercholesterolemic mice in vivo and attenuated monocyte adhesion to atherosclerotic aortas ex vivo. Mechanistic studies identified NADPH oxidase 2 (Nox2)-derived superoxide anion (O2⋅−) as an important downstream signaling molecule stimulating macropinocytosis in monocytes. qRT-PCR identified CD36 as a major scavenger receptor that increases in response to lipid loading in monocytes and deletion of CD36 (Cd36−/−) inhibited foamy monocyte formation in hypercholesterolemic mice. Bulk RNA-sequencing characterized transcriptional differences between non-foamy and foamy monocytes versus macrophages. Finally, flow cytometry analysis of CD14 and CD16 expression demonstrated a significant increase in intermediate monocytes in hypercholesterolemic patients compared to normocholesterolemic controls. These results provide novel insights into the mechanisms of foamy monocyte formation and potentially identify new therapeutic targets for the treatment of atherosclerosis.http://www.sciencedirect.com/science/article/pii/S2213231724004014MonocyteMacropinocytosisnLDLOx-LDLHypercholesterolemiaAtherosclerosis
spellingShingle WonMo Ahn
Faith N. Burnett
Kamila Wojnar-Lason
Jaser Doja
Amritha Sreekumar
Pushpankur Ghoshal
Bhupesh Singla
Graydon Gonsalvez
Ryan A. Harris
Xiaoling Wang
Joseph M. Miano
Gábor Csányi
Activation of receptor-independent fluid-phase pinocytosis promotes foamy monocyte formation in atherosclerotic mice
Redox Biology
Monocyte
Macropinocytosis
nLDL
Ox-LDL
Hypercholesterolemia
Atherosclerosis
title Activation of receptor-independent fluid-phase pinocytosis promotes foamy monocyte formation in atherosclerotic mice
title_full Activation of receptor-independent fluid-phase pinocytosis promotes foamy monocyte formation in atherosclerotic mice
title_fullStr Activation of receptor-independent fluid-phase pinocytosis promotes foamy monocyte formation in atherosclerotic mice
title_full_unstemmed Activation of receptor-independent fluid-phase pinocytosis promotes foamy monocyte formation in atherosclerotic mice
title_short Activation of receptor-independent fluid-phase pinocytosis promotes foamy monocyte formation in atherosclerotic mice
title_sort activation of receptor independent fluid phase pinocytosis promotes foamy monocyte formation in atherosclerotic mice
topic Monocyte
Macropinocytosis
nLDL
Ox-LDL
Hypercholesterolemia
Atherosclerosis
url http://www.sciencedirect.com/science/article/pii/S2213231724004014
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