Visualisation of chicken macrophages using transgenic reporter genes: insights into the development of the avian macrophage lineage.
Bottom Line: The Fms intronic regulatory element (FIRE) within CSF1R is shown to be highly conserved in amniotes and absolutely required for myeloid-restricted expression of fluorescent reporter genes.The cell lineage specificity of reporter gene expression was confirmed by demonstration of coincident expression with the endogenous CSF1R protein.In transgenic birds, expression of the reporter gene provided a defined marker for macrophage-lineage cells, identifying the earliest stages in the yolk sac, throughout embryonic development and in all adult tissues.
Affiliation: The Roslin Institute and Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK email@example.com firstname.lastname@example.org.Show MeSH
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Mentions: We observed CSF1R-transgene-expressing cells in the brain (Fig. 5D). Their CD45+ phenotype and highly ramified appearance is consistent with their identity as microglial cells (Cuadros et al., 2006), the resident macrophage population of neuronal tissues. Similarly, macrophages of the liver (Kupffer cells) were located in the sinusoids, as expected (Fig. 5E). In contrast to mammalian lung, the avian lung does not contain alveoli or cells equivalent to alveolar macrophages, but there is a network of phagocytes surrounding the larger airways (de Geus et al., 2012). Consistent with this pattern, CSF1R-transgene-expressing cells were scattered throughout the interstitial tissue of the parabronchial wall and clustered with B-cells to form small, isolated lymphoid follicles in the lung (Fig. 5F). Epidermal sheet preparations contained large numbers of transgene-expressing cells, both scattered cells and in small clusters (Fig. 5G), consistent with reported distribution of chicken Langerhans cells (Igyártó et al., 2006). Unexpectedly, in the skeletal muscle we observed many CSF1R-transgene-expressing cells. These cells co-expressed class II MHC (Fig. 6H) and were also positive for CSF1R (not shown), indicating they are resident skeletal muscle macrophages. One other macrophage population that is unique to birds is in the skin, where the transgene highlighted the major haematopoietic cell subset in feather pulp (Fig. 5I).Fig. 6.
Affiliation: The Roslin Institute and Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK email@example.com firstname.lastname@example.org.