FTY720 Stimulates 27-Hydroxycholesterol Production and Confers Atheroprotective Effects in Human Primary Macrophages

Abstract

Rationale: The synthetic sphingosine analog FTY720 is undergoing clinical trials as an immunomodulatory compound, acting primarily via sphingosine 1-phosphate receptor activation. Sphingolipid and cholesterol homeostasis are closely connected but whether FTY720 affects atherogenesis in humans is not known. Objective: We examined the effects of FTY720 on the processing of scavenged lipoprotein cholesterol in human primary monocyte-derived macrophages. Methods and Results: FTY720 did not affect cholesterol uptake but inhibited its delivery to the endoplasmic reticulum, reducing cellular free cholesterol cytotoxicity. This was accompanied by increased levels of Niemann-Pick C1 protein (NPC1) and ATP-binding cassette transporter (ABC)A1 proteins and increased efflux of endosomal cholesterol to apolipoprotein A-I. These effects were not dependent on sphingosine 1-phosphate receptor activation. Instead, FTY720 stimulated the production of 27-hydroxycholesterol, an endogenous ligand of the liver X receptor, leading to liver X receptor-induced upregulation of ABCA1. Fluorescently labeled FTY720 was targeted to late endosomes, and the FTY720-induced upregulation of ABCA1 was NPC1-dependent, but the endosomal exit of FTY720 itself was not. Conclusions: We conclude that FTY720 decreases cholesterol toxicity in primary human macrophages by reducing the delivery of scavenged lipoprotein cholesterol to the endoplasmic reticulum and facilitating its release to physiological extracellular acceptors. Furthermore, FTY720 stimulates 27-hydroxycholesterol production, providing an explanation for the atheroprotective effects and identifying a novel mechanism by which FTY720 modulates signaling. (Circ Res. 2010;106:720-729.)

Bis(monoacylglycero)phosphate reduces oxysterol formation and apoptosis in macrophages exposed to oxidized LDL

“…Enhanced formation of non-enzymatically produced oxysterols may then result from cellular cholesterol auto-oxidation, as elicited by increased oxidant stress in oxLDL-loaded macrophages. Sterol 27-hydroxylase (CYP27A1), the enzyme responsible for the formation of 27-hydroxycholesterol, is highly expressed in macrophages [30][31][32]. To our knowledge, the formation of 27-hydroxycholesterol upon oxLDL exposure has not been reported before.…”

Subcellular distribution of FTY720 and FTY720-phosphate in immune cells – another aspect of Fingolimod action relevant for therapeutic application

“…Another study reasoned that FTY720-P is transported out of mouse brain and spinal cord endothelial cells by ABCC1 (Mrp1) (Cartwright et al, 2013). Furthermore, FTY720 was implemented to affect the cholesterol balance and increased the ABCA1 mRNA and protein levels in human primary macrophages (Blom et al, 2010). While these conflicting data are not yet resolved experimentally, the most likely explanation is a cell typeand tissue-specific expression and regulation of sphingolipid transport systems.…”

The Immunosuppressant FTY720 Prolongs Survival in a Mouse Model of Diet-induced Coronary Atherosclerosis and Myocardial Infarction

“…In addition, they reported that FTY720 reduced plasma concentrations of IFN-γ, IL-6 and TNF-α. More recently, Blom et al reported that FTY720 stimulates 27-hydroxycholesterol production and confers athero-protective effects in human primary macrophages (33). As such, FTY720 protects macrophages from free cholesterol-induced toxicity.…”