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Lysosomal oxidation of LDL alters lysosomal pH, induces senescence, and increases secretion of pro-inflammatory cytokines in human macrophages.


ABSTRACT: We have shown that aggregated LDL is internalized by macrophages and oxidized in lysosomes by redox-active iron. We have now investigated to determine whether the lysosomal oxidation of LDL impairs lysosomal function and whether a lysosomotropic antioxidant can prevent these alterations. LDL aggregated by SMase (SMase-LDL) caused increased lysosomal lipid peroxidation in human monocyte-derived macrophages or THP-1 macrophage-like cells, as shown by a fluorescent probe, Foam-LPO. The pH of the lysosomes was increased considerably by lysosomal LDL oxidation as shown by LysoSensor Yellow/Blue and LysoTracker Red. SMase-LDL induced senescence-like properties in the cells as shown by ?-galactosidase staining and levels of p53 and p21. Inflammation plays a key role in atherosclerosis. SMase-LDL treatment increased the lipopolysaccharide-induced secretion of TNF-?, IL-6, and MCP-1. The lysosomotropic antioxidant, cysteamine, inhibited all of the above changes. Targeting lysosomes with antioxidants, such as cysteamine, to prevent the intralysosomal oxidation of LDL might be a novel therapy for atherosclerosis.

SUBMITTER: Ahmad F 

PROVIDER: S-EPMC6314264 | BioStudies | 2019-01-01

REPOSITORIES: biostudies

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