AUTHOR=Lu Mincheng , He Ruiyi , Li Chao , Liu Zixian , Chen Yuhui , Yang Bingsheng , Zhang Xianrong , Yu Bin 

TITLE=Apolipoprotein E deficiency potentiates macrophage against Staphylococcus aureus in mice with osteomyelitis via regulating cholesterol metabolism

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=13

YEAR=2023

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2023.1187543

DOI=10.3389/fcimb.2023.1187543

ISSN=2235-2988

ABSTRACT=<sec><title>Introduction</title><p><italic>Staphylococcus aureus</italic> (<italic>S. aureus</italic>) osteomyelitis causes a variety of metabolism disorders in microenvironment and cells. Defining the changes in cholesterol metabolism and identifying key factors involved in cholesterol metabolism disorders during <italic>S. aureus</italic> osteomyelitis is crucial to understanding the mechanisms of <italic>S. aureus</italic> osteomyelitis and is important in designing host-directed therapeutic strategies.</p></sec><sec><title>Methods</title><p>In this study, we conducted <italic>in vitro</italic> and <italic>in vivo</italic> experiments to define the effects of <italic>S. aureus</italic> osteomyelitis on cholesterol metabolism, as well as the role of Apolipoprotein E (ApoE) in regulating cholesterol metabolism by macrophages during <italic>S. aureus</italic> osteomyelitis.</p></sec><sec><title>Results</title><p>The data from GSE166522 showed that cholesterol metabolism disorder was induced by <italic>S. aureus</italic> osteomyelitis. Loss of cholesterol from macrophage obtained from mice with <italic>S. aureus</italic> osteomyelitis was detected by liquid chromatography-tandem mass spectrometry(LC-MS/MS), which is consistent with Filipin III staining results. Changes in intracellular cholesterol content influenced bactericidal capacity of macrophage. Subsequently, it was proven by gene set enrichment analysis and qPCR, that ApoE played a key role in developing cholesterol metabolism disorder in <italic>S. aureus</italic> osteomyelitis. ApoE deficiency in macrophages resulted in increased resistance to <italic>S. aureus</italic>. ApoE-deficient mice manifested abated bone destruction and decreased bacteria load. Moreover, the combination of transcriptional analysis, qPCR, and killing assay showed that ApoE deficiency led to enhanced cholesterol biosynthesis in macrophage, ameliorating anti-infection ability.</p></sec><sec><title>Conclusion</title><p>We identified a previously unrecognized role of ApoE in <italic>S. aureus</italic> osteomyelitis from the perspective of metabolic reprogramming. Hence, during treating <italic>S. aureus</italic> osteomyelitis, considering cholesterol metabolism as a potential therapeutic target presents a new research direction.</p></sec>