Basic Study
Copyright ©The Author(s) 2023. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Diabetes. Mar 15, 2023; 14(3): 222-233
Published online Mar 15, 2023. doi: 10.4239/wjd.v14.i3.222
Nε-(carboxymethyl)lysine promotes lipid uptake of macrophage via cluster of differentiation 36 and receptor for advanced glycation end products
Zhong-Qun Wang, Hai-Peng Yao, Zhen Sun
Zhong-Qun Wang, Hai-Peng Yao, Zhen Sun, Department of Cardiology, Affiliated Hospital of Jiangsu University, Zhenjiang 212001, Jiangsu Province, China
Author contributions: Sun Z designed the research study; Wang Z and Yao HP performed the research; Wang Z analyzed the data and wrote the manuscript; All authors have read and approve the final manuscript.
Supported by The National Natural Science Foundation of China, No. 82070455; Natural Science Foundation of Jiangsu Province, No. BK20201225; Medical Innovation Team Project of Jiangsu Province, No. CXTDA2017010.
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Zhen Sun, PhD, Doctor, Department of Cardiology, Affiliated Hospital of Jiangsu University, No. 438 Jiefang Road, Zhenjiang 212001, Jiangsu Province, China. 1398041019@qq.com
Received: September 22, 2022
Peer-review started: September 22, 2022
First decision: December 26, 2022
Revised: January 8, 2023
Accepted: February 15, 2023
Article in press: February 15, 2023
Published online: March 15, 2023
Processing time: 174 Days and 7.9 Hours
Abstract
BACKGROUND

Advanced glycation end products (AGEs) are diabetic metabolic toxic products that cannot be ignored. Nε-(carboxymethyl)lysine (CML), a component of AGEs, could increase macrophage lipid uptake, promote foam cell formation, and thereby accelerate atherosclerosis. The receptor for AGEs (RAGE) and cluster of differentiation 36 (CD36) were the receptors of CML. However, it is still unknown whether RAGE and CD36 play key roles in CML-promoted lipid uptake.

AIM

Our study aimed to explore the role of RAGE and CD36 in CML-induced mac-rophage lipid uptake.

METHODS

In this study, we examined the effect of CML on lipid uptake by Raw264.7 macrophages. After adding 10 mmol/L CML, the lipid accumulation in macro-phages was confirmed by oil red O staining. Expression changes of CD36 and RAGE were detected with immunoblotting and quantitative real-time polymerase chain reaction. The interaction between CML with CD36 and RAGE was verified by immunoprecipitation. We synthesized a novel N-succinimidyl-4-18F-fluorobenzoate-CML radioactive probe. Radioactive receptor-ligand binding assays were performed to test the binding affinity between CML with CD36 and RAGE. The effects of blocking CD36 or RAGE on CML-promoting lipid uptake were also detected.

RESULTS

The study revealed that CML significantly promoted lipid uptake by macro-phages. Immunoprecipitation and radioactive receptor-ligand binding assays indicated that CML could specifically bind to both CD36 and RAGE. CML had a higher affinity for CD36 than RAGE. ARG82, ASN71, and THR70 were the potential interacting amino acids that CD36 binds to CML Anti-CD36 and anti-RAGE could block the uptake of CML by macrophages. The lipid uptake promotion effect of CML was significantly attenuated after blocking CD36 or RAGE.

CONCLUSION

Our results suggest that the binding of CML with CD36 and RAGE promotes macrophage lipid uptake.

Keywords: Nε-(carboxymethyl)lysine, Cluster of differentiation 36, Receptor for advanced glycation end products, Lipid uptake, Macrophage

Core Tip: Nε-(carboxymethyl)lysine (CML), a toxic metabolism product in diabetes mellites, is a causative factor of many diseases. CML has been reported to promote lipid uptake in macrophages and foam cell formation. The receptor for advanced glycation end products (RAGE) and cluster of differentiation 36 (CD36) are receptors of CML. However, the roles of RAGE and CD36 in CML-induced lipid uptake in macrophages are currently unclear. Moreover, the relationship and difference between RAGE and CD36 in this process are also worth exploring. The in vitro model was constructed with Raw264.7 cells. Under the stimulation of CML, the lipid uptake by cells was significantly increased. Inhibition of CD36 or RAGE antagonized CML-induced lipid uptake. We synthesized a probe of 18F-CML to explore the relationship of CML to CD36 and to RAGE. CML could bind to CD36 and to RAGE, and CML has a significantly stronger affinity for CD36 than for RAGE. The exploration of the pathogenic mechanism of CML may provide evidence for a deeper understanding of diseases related to metabolic disorders.