Niacin promotes the efflux of lysosomal cholesterol from macrophages via the CD38/NAADP signaling pathway.

Exp Biol Med (Maywood)

Department of Cardiology, Guangxi Health Commission Key Laboratory of Basic Research in Sphingolipid Metabolism Related Diseases, The Affiliated Hospital of Guilin Medical University, Guilin 541001, China.

Published: June 2022

The accumulation of free cholesterol in macrophage lysosomes significantly enhances atherogenesis. Our recent study demonstrated that the cluster of differentiation 38 (CD38)/nicotinic acid adenine dinucleotide phosphate (NAADP)/Ca signaling pathway plays a critical role in the efflux of lysosomal free cholesterol from macrophages in atherosclerosis. Niacin, known as nicotinic acid, is one of the oldest lipid-lowering medications showing unique anti-atherosclerotic activity. However, it is unknown whether this anti-atherosclerosis activity is associated with the efflux of lysosomal compartmentalized cholesterol in macrophages. In this study, we investigated the anti-atherosclerotic effects of niacin on the reduction of lysosomal free cholesterol via CD38/NAADP signaling in macrophages derived from low-density lipoprotein receptor (LDLr) mice. Fluorescent filipin and Nile red labeling coupled with confocal microscopy demonstrated that niacin reduced free cholesterol accumulation in lysosomes in a concentration-dependent manner. Transmission electron microscopy also showed that niacin markedly decreased cholesterol crystal formation in lysosomes in oxidized LDL-containing LDLr bone marrow-derived macrophages. Enzyme-linked immunosorbent assays showed that niacin increased NAADP production in a concentration-dependent manner, which was inhibited by small interfering RNA interference of CD38. Therefore, niacin may promote the efflux of lysosomal cholesterol from macrophages via the CD38/NAADP signaling pathway.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9265522PMC
http://dx.doi.org/10.1177/15353702221084632DOI Listing

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