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Updated: Dec 25, 2025
Macrophage Differentiation and Polarization into an M2-Like Phenotype using a Human Monocyte-Like THP-1 Leukemia Cell Line
Published on: August 2, 2021
TLR-2-mediated metabolic reprogramming participates in polyene phosphatidylcholine-mediated inhibition of M1
Ting-Ting Feng1, Xiao-Ying Yang2, Shan-Shan Hao2
1Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Tongshan Road 209, Xuzhou, 221004, Jiangsu Province, People's Republic of China.
Abstract:
This study aimed to investigate whether the classic hepatoprotective drug polyene phosphatidylcholine (PPC) regulates macrophage polarization and explores the potential role of TLR-2 in this process. In RAW264.7 macrophages and murine bone marrow-derived macrophages (BMDMs) stimulated by lipopolysaccharide (LPS), PPC significantly inhibited the production of IL-6, TNF-α, and the mRNA expression of M1-type macrophage markers. Consistently, PPC reduced the mRNA expression of several key enzymes in the pathways of glycolysis and lipid synthesis while increasing the expression of key enzymes associated with lipid oxidation. Moreover, blocking the glycolytic pathway using 2-deoxy-D-glucose (2-DG) significantly enhanced the anti-inflammatory effect of PPC. However, inhibition of lipid oxidation using GW9662 (an inhibitor of PPAR-γ) and GW6471 (an inhibitor of PPAR-α) abolished the anti-inflammatory effect of PPC. Interestingly, TLR-2 expression in macrophages was significantly downregulated after exposure to PPC. Moreover, pre-activation of TLR-2 hampered the anti-inflammatory effect of PPC. In addition, PPC did not inhibit the secretion of IL-6 and TNF-α in TLR-2-/- BMDMs that were activated by LPS. This was consistent with the increased expression of M1 markers and glycolytic and lipid synthesis enzymes but decreased lipid oxidation-related enzymes. These results showed that PPC inhibits the differentiation of M1-type macrophages, which was most likely related to TLR-2-mediated metabolic reprogramming.
Insights
Polyene phosphatidylcholine (PPC) suppresses pro-inflammatory M1 macrophage polarization by reprogramming cellular metabolism. This hepatoprotective effect is mediated through Toll-like receptor 2 (TLR-2), highlighting a novel therapeutic pathway.
Area of Science:
- Immunology
- Cell Biology
- Pharmacology
Background:
- Macrophage polarization is crucial in immune responses.
- M1 macrophages contribute to inflammation.
- Polyene phosphatidylcholine (PPC) is a known hepatoprotective drug.
Purpose of the Study:
- To investigate if PPC regulates macrophage polarization.
- To explore the role of Toll-like receptor 2 (TLR-2) in PPC's effects on macrophages.
Main Methods:
- Utilized RAW264.7 and murine bone marrow-derived macrophages (BMDMs).
- Stimulated macrophages with lipopolysaccharide (LPS).
- Assessed cytokine production (IL-6, TNF-α), M1 marker expression, and metabolic enzyme activity.
- Employed pathway inhibitors (2-DG, GW9662, GW6471) and TLR-2 knockout macrophages.
Main Results:
- PPC significantly inhibited M1 macrophage markers and pro-inflammatory cytokines (IL-6, TNF-α).
- PPC modulated macrophage metabolism, reducing glycolysis/lipid synthesis and increasing lipid oxidation.
- TLR-2 expression was downregulated by PPC, and its absence abolished PPC's anti-inflammatory effects.
- Inhibition of glycolysis enhanced PPC's effect, while inhibition of lipid oxidation negated it.
Conclusions:
- PPC inhibits M1 macrophage differentiation.
- The anti-inflammatory action of PPC is linked to TLR-2-mediated metabolic reprogramming.
- PPC represents a potential therapeutic agent for inflammatory conditions by modulating macrophage phenotype and metabolism.
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