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Macrophage Differentiation and Polarization into an M2-Like Phenotype using a Human Monocyte-Like THP-1 Leukemia Cell Line
Published on: August 2, 2021
Human plasma membrane-derived vesicles halt proliferation and induce differentiation of THP-1 acute monocytic
Ephraim A Ansa-Addo1, Sigrun Lange, Dan Stratton
1Cellular and Molecular Immunology Research Centre, School of Human Sciences, Faculty of Life Sciences, London Metropolitan University, London, United Kingdom.
Abstract:
Plasma membrane-derived vesicles (PMVs) are small intact vesicles released from the cell surface that play a role in intercellular communication. We have examined the role of PMVs in the terminal differentiation of monocytes. The myeloid-differentiating agents all-trans retinoic acid/PMA and histamine, the inflammatory mediator that inhibits promonocyte proliferation, induced an intracellular Ca(2+)-mediated PMV (as opposed to exosome) release from THP-1 promonocytes. These PMVs cause THP-1 cells to enter G(0)-G(1) cell cycle arrest and induce terminal monocyte-to-macrophage differentiation. Use of the TGF-β receptor antagonist SB-431542 and anti-TGF-β1 Ab showed that this was due to TGF-β1 carried on PMVs. Although TGF-β1 levels have been shown to increase in cell culture supernatants during macrophage differentiation and dendritic cell maturation, the presence of TGF-β1 in PMVs is yet to be reported. In this study, to our knowledge we show for the first time that TGF-β1 is carried on the surface of PMVs, and we confirm the presence within PMVs of certain leaderless proteins, with reported roles in myeloid cell differentiation. Our in vitro findings support a model in which TGF-β1-bearing PMVs, released from promonocytic leukemia cells (THP-1) or primary peripheral blood monocytes on exposure to sublytic complement or after treatment with a differentiation therapy agent, such as all-trans retinoic acid, significantly reduce proliferation of THP-1 cells. Such PMVs also induce the terminal differentiation of primary peripheral blood monocytes as well as THP-1 monocytes.
Insights
Plasma membrane-derived vesicles (PMVs) carrying TGF-β1 induce monocyte differentiation and cell cycle arrest. This study reveals PMVs as key mediators in monocyte-to-macrophage differentiation.
Area of Science:
- Cell Biology
- Immunology
- Biochemistry
Background:
- Plasma membrane-derived vesicles (PMVs) mediate intercellular communication.
- The role of PMVs in monocyte differentiation is not fully understood.
- Transforming growth factor-beta 1 (TGF-β1) is implicated in myeloid cell differentiation.
Purpose of the Study:
- To investigate the role of PMVs in the terminal differentiation of monocytes.
- To determine if PMVs carry TGF-β1 and mediate its effects on monocyte differentiation.
- To elucidate the mechanism of PMV-induced monocyte differentiation.
Main Methods:
- THP-1 promonocytes were treated with myeloid-differentiating agents (all-trans retinoic acid/PMA, histamine).
- PMV release was induced and characterized.
- TGF-β receptor antagonist (SB-431542) and anti-TGF-β1 antibody were used to assess TGF-β1's role.
- PMVs were analyzed for carried proteins, including TGF-β1.
Main Results:
- Myeloid-differentiating agents induced intracellular Ca(2+)-mediated PMV release from THP-1 cells.
- These PMVs induced G(0)-G(1) cell cycle arrest and terminal monocyte-to-macrophage differentiation.
- TGF-β1 was identified as a key component carried by PMVs, mediating differentiation.
- The study confirmed the presence of leaderless proteins within PMVs involved in myeloid differentiation.
Conclusions:
- PMVs carrying TGF-β1 are released from monocytes upon stimulation.
- These TGF-β1-bearing PMVs induce cell cycle arrest and terminal differentiation of monocytes into macrophages.
- This study provides novel insights into the mechanism of monocyte differentiation mediated by PMVs.
