Korean Circ J.  2021 Jan;51(1):68-80. 10.4070/kcj.2020.0117.

Nlrp3, Csf3, and Edn1 in Macrophage Response to Saturated Fatty Acids and Modified Low-Density Lipoprotein

Affiliations
  • 1Graduate Program of Science for Aging, Graduate School of Yonsei University, Seoul, Korea
  • 2Division of Cardiology, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
  • 3Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, Korea

Abstract

Background and Objectives
The relationship between metabolic stress, inflammation, and cardiovascular disease is being studied steadily. The aim of this study was to evaluate the effect of palmitate (PA) and minimally modified low-density lipoprotein (mmLDL) on macrophages and to identify the associated pathways.
Methods
J774 macrophages were incubated with PA or mmLDL and lipopolysaccharide (LPS). Secretion of inflammatory chemokines and the expression of corresponding genes were determined. The phosphorylation of extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase was also assessed. RNA sequencing of macrophages was performed to identify the genes regulated by PA or mmLDL. Some of the genes regulated by the 2 agents were validated by knocking down the cells using small interfering RNA.
Results
PA or mmLDL promoted the secretion of interleukin (IL)-6 and IL-1β in LPSstimulated macrophages, and this was accompanied by higher phosphorylation of ERK. RNA sequencing revealed dozens of genes that were regulated in this process, such as Csf3 and Edn1, which were affected by PA and mmLDL, respectively. These agents also increased Nlrp3 expression. The effect of Csf3 or Edn1 silencing on inflammation was modest, whereas toll-like receptor (TLR) 4 inhibition reduced a large proportion of macrophage activation.
Conclusions
We demonstrated that the proinflammatory milieu with high levels of PA or mmLDL promoted macrophage activation and the expression of associated genes such as Nlrp3, Csf3, and Edn1. Although the TLR4 pathway appeared to be most relevant, additional role of other genes in this process provided insights regarding the potential targets for intervention.

Keyword

Atherosclerosis; Metabolic syndrome; Immunity; Obesity
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