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Updated: May 29, 2025
Culture of Macrophage Colony-stimulating Factor Differentiated Human Monocyte-derived Macrophages
Published on: June 30, 2016
Path of differentiation defines human macrophage identity
Abstract:
Macrophages play central roles in immunity, wound healing, and homeostasis - a functional diversity that is underpinned by varying developmental origins. The impact of ontogeny on properties of human macrophages is inadequately understood. We demonstrate that definitive human fetal liver (HFL) hematopoietic stem cells (HSCs) possess two divergent paths of macrophage specification that lead to distinct identities. The monocyte-dependent pathway exists in both prenatal and postnatal hematopoiesis and generates macrophages with adult-like responses properties. We now uncover a fetal-specific pathway of expedited differentiation that generates tissue resident-like macrophages (TRMs) that retain HSC-like self-renewal programs governed by the aryl hydrocarbon receptor (AHR). We show that AHR antagonism promotes TRM expansion and mitigates inflammation in models of atopic dermatitis (AD). Overall, we directly connect path of differentiation with functional properties of macrophages and identify an approach to promote selective expansion of TRMs with direct relevance to inflammation and diseases of macrophage dysfunction.
Insights
Human fetal liver stem cells generate two distinct macrophage types. A novel pathway creates tissue-resident macrophages (TRMs) with self-renewal, offering a target for treating inflammatory diseases like atopic dermatitis.
Area of Science:
- Immunology
- Developmental Biology
- Stem Cell Biology
Background:
- Macrophages are crucial for immunity, wound healing, and homeostasis.
- Their functional diversity is linked to developmental origins, but human ontogeny's impact is unclear.
- Human fetal liver (HFL) hematopoietic stem cells (HSCs) are key to understanding early macrophage development.
Purpose of the Study:
- To investigate the divergent pathways of macrophage specification from human fetal liver HSCs.
- To characterize the distinct identities and properties of macrophages derived from these pathways.
- To explore the therapeutic potential of targeting these pathways in inflammatory conditions.
Main Methods:
- Utilized human fetal liver HSCs to trace macrophage differentiation pathways.
- Employed aryl hydrocarbon receptor (AHR) antagonism to modulate macrophage populations.
- Assessed macrophage properties, including self-renewal and inflammatory responses.
- Validated findings in preclinical models of atopic dermatitis (AD).
Main Results:
- Identified two distinct macrophage specification pathways from HFL HSCs: a monocyte-dependent pathway and a fetal-specific expedited differentiation pathway.
- The fetal pathway generates tissue-resident-like macrophages (TRMs) exhibiting HSC-like self-renewal, regulated by AHR.
- AHR antagonism promoted TRM expansion and reduced inflammation in atopic dermatitis models.
- Directly linked differentiation pathways to specific macrophage functional properties.
Conclusions:
- Human fetal macrophage development involves distinct ontogenetic pathways with differing functional outcomes.
- AHR-regulated TRMs represent a promising target for managing inflammatory diseases.
- Targeting macrophage differentiation offers a novel therapeutic strategy for diseases involving macrophage dysfunction.
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