In Vivo Pravastatin Treatment Reverses Hypercholesterolemia Induced Mitochondria-Associated Membranes Contact Sites, Foam Cell Formation, and Phagocytosis in Macrophages.

Helena Coutinho Franco de Oliveira,Thiago Rentz,Leandro Henrique de Paula Assis,Gabriel de Gabriel Dorighello,Aníbal Eugênio Vercesi,Jane Cristina de Souza

doi:10.3389/fmolb.2022.839428

Helena Coutinho Franco de Oliveira, Thiago Rentz + Show 4 more

Open Access

https://doi.org/10.3389/fmolb.2022.839428

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Abstract

Statins are successful drugs used to treat hypercholesterolemia, a primary cause of atherosclerosis. In this work, we investigated how hypercholesterolemia and pravastatin treatment impact macrophage and mitochondria functions, the key cell involved in atherogenesis. By comparing bone marrow-derived macrophages (BMDM) of wild-type (WT) and LDL receptor knockout (LDLr−/−) mice, we observed hypercholesterolemia increased the number of contact sites at mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs), enhanced mitochondrial hydrogen peroxide release, altered the gene expression of inflammatory markers, and increased oxidized LDL (ox-LDL) uptake and phagocytic activity. Three months of in vivo pravastatin treatment of LDLr−/− mice reversed the number of contact sites at the MAM, ox-LDL uptake, and phagocytosis in LDLr−/− BMDM. Additionally, pravastatin increased BMDM mitochondrial network branching. In peritoneal macrophages (PMs), hypercholesterolemia did not change MAM stability, but stimulated hydrogen peroxide production and modulated gene expression of pro- and anti-inflammatory markers. It also increased mitochondrial branching degree and had no effects on ox-LDL uptake and phagocytosis in PM. Pravastatin treatment increased superoxide anion production and changed inflammation-related gene expression in LDLr−/− PM. In addition, pravastatin increased markedly the expression of the mitochondrial dynamics-related genes Mfn2 and Fis1 in both macrophages. In summary, our results show that hypercholesterolemia and pravastatin treatment affect macrophage mitochondria network structure as well as their interaction with the endoplasmic reticulum (ER). These effects impact on macrophage conversion rates to foam cell and macrophage phagocytic capacity. These findings associate MAM stability changes with known mechanisms involved in atherosclerosis progression and resolution.

Highlights

Atherosclerosis is a silent and chronic inflammatory illness characterized by cholesterol-enriched plaque deposition in the arteries (Goldstein and Brown, 2015)
bone marrow-derived macrophages (BMDM) of LDLr−/− mice presented a marked 2.6-fold increase in endoplasmic reticulum (ER)-mitochondria contact sites when compared with cells of WT mice (Figures 1A,B)
We verified that hypercholesterolemia increases and pravastatin treatment decreases the number of contact sites at the mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs) in both types of macrophages, peritoneal macrophages (PMs) and BMDM

Summary

Introduction

Atherosclerosis is a silent and chronic inflammatory illness characterized by cholesterol-enriched plaque deposition in the arteries (Goldstein and Brown, 2015). Elevated low-density lipoprotein (LDL) levels in the plasma (hypercholesterolemia) trigger atherogenesis. This condition favors LDL retention in the subendothelial space of the arteries, followed by lipoprotein oxidation. Mainly monocytes, infiltrate into the arterial intima, differentiate into macrophages that take up ox-LDL, and become cholesterol-laden foam cells (Brown and Goldstein, 1983), the hallmark of atherosclerosis (Steinberg and Witztum, 2010; Gao et al, 2017). These activated macrophages secrete pro-inflammatory cytokines (Chinetti-Gbaguidi et al, 2015), perpetuating the inflammation

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