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Updated: Feb 17, 2026
Reprograming Model of Human Monocyte-derived Macrophages for In-vitro Assays
Published on: April 18, 2025
PRR signaling during in vitro macrophage differentiation from progenitors modulates their subsequent response to
Alba Martínez1, Cristina Bono1, Javier Megías2
1Departamento de Microbiología y Ecología, Universitat de València, Burjassot, Spain, Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universitat de València, Burjassot, Spain.
Abstract:
Toll-like receptor (TLR) agonists drive hematopoietic stem and progenitor cells (HSPCs) to differentiate along the myeloid lineage in vitro and also in vivo following infection. In this study, we used an in vitro model of HSPC differentiation to investigate the functional consequences (cytokine production) that exposing HSPCs to various pathogen-associated molecular patterns (PAMPs) and Candida albicans cells have on the subsequently derived macrophages. Mouse HSPCs (Lin- cells) were cultured with GM-CSF to induce macrophage differentiation in the presence or absence of the following pattern recognition receptor (PRR) agonists: Pam3CSK4 (TLR2 ligand), LPS (TLR4 ligand), depleted zymosan (which only activates Dectin-1), or inactivated C. albicans yeasts (which activate several PRRs, mainly TLR2 and Dectin-1). Our data show that only pure TLR2 ligand exposure (transient and continuous) impacts the inflammatory function of GM-CSF-derived macrophages, because Pam3CSK4-exposed HSPCs generate macrophages with a diminished ability to produce inflammatory cytokines. Interestingly, the Pam3CSK4-induced tolerance of macrophages (by transient exposure of HSPCs) is reinforced by subsequent exposure to C. albicans cells in GM-CSF-derived macrophages; however, the induced tolerance is partially reversed in M-CSF-derived macrophages. Therefore, the ability of macrophages to produce inflammatory cytokines is extremely dependent on how the HSPCs from which they are derived receive and integrate multiple microenvironmental signals (PRR ligands and/or CSFs).
Insights
Hematopoietic stem and progenitor cells (HSPCs) exposed to Toll-like receptor 2 (TLR2) ligands develop into macrophages with reduced inflammatory cytokine production. This TLR2-induced tolerance in macrophages is influenced by subsequent signals and differentiation factors.
Area of Science:
- Immunology
- Cell Biology
- Hematopoiesis
Background:
- Toll-like receptor (TLR) agonists influence hematopoietic stem and progenitor cell (HSPC) differentiation towards myeloid lineages.
- Understanding how pathogen-associated molecular patterns (PAMPs) affect macrophage function derived from HSPCs is crucial for immune response modulation.
Purpose of the Study:
- To investigate the functional consequences of exposing HSPCs to various pattern recognition receptor (PRR) agonists on the cytokine production of subsequently derived macrophages.
- To determine the impact of different PRR ligands and differentiation factors on macrophage inflammatory responses.
Main Methods:
- Mouse HSPCs (Lin- cells) were cultured with GM-CSF for macrophage differentiation.
- HSPCs were exposed to various PRR agonists: Pam3CSK4 (TLR2), LPS (TLR4), depleted zymosan (Dectin-1), or inactivated Candida albicans.
- Cytokine production by the resulting macrophages was analyzed.
Main Results:
- Exposure to a pure TLR2 ligand (Pam3CSK4) during HSPC differentiation resulted in macrophages with diminished inflammatory cytokine production.
- TLR2-induced tolerance in GM-CSF-derived macrophages was reinforced by subsequent Candida albicans exposure but partially reversed in M-CSF-derived macrophages.
- Macrophage inflammatory function is highly dependent on the integration of microenvironmental signals by HSPCs.
Conclusions:
- TLR2 ligand exposure during HSPC differentiation significantly impacts the inflammatory potential of derived macrophages.
- The differentiation pathway (GM-CSF vs. M-CSF) and exposure to multiple signals modulate the development of immune tolerance in macrophages.
- HSPC integration of diverse signals dictates the functional capacity of mature macrophages, highlighting a critical checkpoint in immune regulation.
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