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Importance of Acid Sphingomyelinase in Subendothelial Accumulation of Exosomes and Inflammatory Response in Mouse Carotid Arteries
Author(s) -
Yuan Xinxu,
Bhat Owais M.,
Camus Sarah,
Zhang Yang,
Gulbins Erich,
Li Pin-Lan
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.06282
Subject(s) - acid sphingomyelinase , sphingomyelin phosphodiesterase , inflammasome , pyroptosis , microvesicles , exosome , microbiology and biotechnology , chemistry , biology , sphingomyelin , inflammation , immunology , biochemistry , cholesterol , microrna , gene
Exosomes have been demonstrated to be one of the factors regulating the release of various intracellular signaling molecules to mediate cell‐to‐cell communication. However, it remains unknown whether exosomes mediate the release of NLRP3 inflammasome products to the subendothelial matrix (SEM), thus promoting development of vascular injury or diseases. The present study tested a hypothesis that lysosomal acid sphingomyelinase (ASM) importantly controls exosome release of NLRP3 inflammasome activating products such as interleukin 1 beta (IL‐1β), which may be aggregated in the subendothelial space leading to local vascular inflammatory response and injury. Using an endothelial ASM‐specific overexpression (Smpd1 trg /EC cre ) mouse model with partial carotid ligation, we found that Smpd1 trg /EC cre mice treated with Western diet (WD) exhibited a remarkable increase in the expression of exosome markers such as CD63, CD9 and Annexin II in the endothelium compared to wild type mice (WT/WT), as detected with immunohistochemistry staining (IHC). These pathological changes were substantially abolished by pretreatment of the mice with amitriptyline, an acid sphingomyelinase (ASM) inhibitor. Interestingly, we found that exosomes accumulation occurred in subendothelial space as shown by increased colocalization of exosome markers such as CD63 and CD9 with SEM markers decorin or versican detected by confocal microscopy. Also, NLRP3 inflammasome activating product, IL‐1β was found accumulated in the SEM. When mice were pretreated with Ami, this exosomes and IL‐1β subendothelial accumulation was almost completely blocked, which was accompanied by marked attenuation of neointima proliferation. In the cultured carotid arterial endothelial cells (CAECs) from Smpd1 trg /EC cre , 7‐ketocholesterol (7‐ket) significantly increased the exosome release compared to those cells from WT/WT mice as detected by Nanoparticle Tracking Analysis (NTA). Ami treatment significantly reduced 7‐ket‐induced exosome release and reduction of lysosome‐multivesicular body (MVB) interactions shown by the colocalization of VPS16 with lamp‐1. These results confirm the idea that lysosomal ASM contributes to exosome‐mediated release of IL‐1β that leads to local arterial inflammation and associated arterial diseases. Support or Funding Information Supported by HL057244, HL075316