Related Experiment Video
Updated: Dec 22, 2025
Isolation and RNA Extraction of Neurons, Macrophages and Microglia from Larval Zebrafish Brains
Published on: April 27, 2018
Zebrafish macrophage developmental arrest underlies depletion of microglia and reveals Csf1r-independent metaphocytes
Laura E Kuil1, Nynke Oosterhof1, Giuliano Ferrero2
1Department of Clinical Genetics, Erasmus University Medical Center Rotterdam, Rotterdam, Netherlands.
Abstract:
Macrophages derive from multiple sources of hematopoietic progenitors. Most macrophages require colony-stimulating factor 1 receptor (CSF1R), but some macrophages persist in the absence of CSF1R. Here, we analyzed mpeg1:GFP-expressing macrophages in csf1r-deficient zebrafish and report that embryonic macrophages emerge followed by their developmental arrest. In larvae, mpeg1+ cell numbers then increased showing two distinct types in the skin: branched, putative Langerhans cells, and amoeboid cells. In contrast, although numbers also increased in csf1r-mutants, exclusively amoeboid mpeg1+ cells were present, which we showed by genetic lineage tracing to have a non-hematopoietic origin. They expressed macrophage-associated genes, but also showed decreased phagocytic gene expression and increased epithelial-associated gene expression, characteristic of metaphocytes, recently discovered ectoderm-derived cells. We further demonstrated that juvenile csf1r-deficient zebrafish exhibit systemic macrophage depletion. Thus, csf1r deficiency disrupts embryonic to adult macrophage development. Zebrafish deficient for csf1r are viable and permit analyzing the consequences of macrophage loss throughout life.
Insights
Colony-stimulating factor 1 receptor (CSF1R) is crucial for most macrophages. Zebrafish lacking CSF1R develop unique, non-hematopoietic amoeboid cells, revealing CSF1R
Area of Science:
- Immunology
- Developmental Biology
- Zebrafish Models
Background:
- Macrophages are essential immune cells derived from hematopoietic progenitors.
- Colony-stimulating factor 1 receptor (CSF1R) signaling is critical for macrophage development and survival.
- Some macrophage populations persist independently of CSF1R, suggesting alternative origins or regulatory mechanisms.
Purpose of the Study:
- To investigate the origin and characteristics of macrophages in zebrafish lacking functional CSF1R.
- To analyze the impact of CSF1R deficiency on macrophage development from embryonic to juvenile stages.
- To identify alternative cell types that may compensate for macrophage loss in CSF1R-deficient zebrafish.
Main Methods:
- Analysis of mpeg1:GFP-expressing cells in csf1r-deficient zebrafish.
- Genetic lineage tracing to determine cell origins.
- Gene expression analysis to characterize cell identity (macrophage-associated, phagocytic, epithelial-associated genes).
- Assessment of phagocytic activity and systemic macrophage populations.
Main Results:
- Embryonic macrophages emerged but arrested development in csf1r-deficient zebrafish.
- Larval skin showed branched (putative Langerhans cells) and amoeboid mpeg1+ cells in wild-type, but exclusively amoeboid cells in csf1r-mutants.
- The amoeboid mpeg1+ cells in mutants were of non-hematopoietic origin, expressing macrophage and epithelial genes, characteristic of metaphocytes.
- Juvenile csf1r-deficient zebrafish exhibited systemic macrophage depletion.
- csf1r deficiency disrupts embryonic to adult macrophage development.
Conclusions:
- csf1r deficiency leads to the emergence of non-hematopoietic, ectoderm-derived metaphocytes that exhibit some macrophage-like characteristics.
- The study highlights the critical role of CSF1R in conventional macrophage development and reveals alternative cell populations in its absence.
- csf1r-deficient zebrafish provide a valuable model for studying the consequences of systemic macrophage loss throughout life.
