Apolipoprotein M promotes the anti-inflammatory effect of high-density lipoprotein by binding to scavenger receptor BI

Shuang Yao; Guanghua Luo; Hong Liu; Jun Zhang; Yuxia Zhan; Ning Xu; Xiaoying Zhang; Lu Zheng

doi:10.21037/atm-20-7008

Apolipoprotein M promotes the anti-inflammatory effect of high-density lipoprotein by binding to scavenger receptor BI

Ann Transl Med. 2020 Dec;8(24):1676. doi: 10.21037/atm-20-7008.

Authors

Shuang Yao¹, Guanghua Luo¹, Hong Liu², Jun Zhang¹, Yuxia Zhan¹, Ning Xu³, Xiaoying Zhang², Lu Zheng¹

Affiliations

¹ Clinical Medical Research Center, the Third Afﬁliated Hospital of Soochow University, Changzhou, China.
² Department of Cardiothoracic Surgery, the Third Affiliated Hospital of Soochow University, Changzhou, China.
³ Division of Clinical Chemistry and Pharmacology, Department of Laboratory Medicine, Lunds University, Lunds, Sweden.

Abstract

Background: Inflammation participates pivotally in the pathogenesis of atherosclerosis. Apolipoprotein M (apoM) is a high-density lipoprotein (HDL)-associated plasma protein that affects HDL metabolism and shows various anti-inflammatory functions in atherosclerosis. In this study, we aim to determine whether apoM is expressed in peripheral blood mononuclear cells (PBMCs) and promoted the anti-inflammatory effect of HDL by combing with scavenger receptor BI (SR-BI).

Methods: The expression of apoM in PBMCs is detected by a confocal fluorescence microscope and flow cytometry. The interactions between apoM and SR-BI are detected with co-immunoprecipitation. The multiplexed Luminex xMAP assay detects the inflammatory factors induced by apoM⁺ HDL and apoM^- HDL in inflammatory cell model.

Results: ApoM is expressed on CD14⁺ monocytes, CD3⁺ T cells, and CD19⁺ B cells, CD16⁺ and CD56⁺ NK cells. CD14⁺ monocytes have the highest ratio of apoM⁺ cells. ApoM⁺ HDL, apoM^- HDL, and recombinant apoM protein could be co-precipitated with SR-BI on the surface of human THP-1 monocytic leukemia cells. In vitro, apoM⁺ HDL induces significantly less expression of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-1β than apoM^- HDL.

Conclusions: ApoM was expressed on all PBMCs. ApoM interacted with SR-BI on THP-1. ApoM⁺ HDL has a more significant anti-inflammatory effect than apoM^- HDL.

Keywords: Apolipoprotein M (apoM); high-density lipoprotein (HDL); inflammatory effect; peripheral blood mononuclear cell (PBMC); scavenger receptor class B type I.