ABSTRACT: Capacity of yolk sac macrophages, fetal liver and adult monocytes to colonize an empty niche and develop into functional tissue resident macrophages
Project description:Tissue-resident macrophages can derive from yolk sac macrophages, fetal liver monocytes or adult bone marrow monocytes. Whether these precursors can give rise to transcriptionally identical alveolar macrophages is unknown. Here, we transferred traceable yolk sac macrophages, fetal liver monocytes, adult bone marrow monocytes or adult alveolar macrophages as a control, into the empty alveolar macrophage niche of neonatal Csf2rb-/- mice. All precursors efficiently colonized the alveolar niche and generated alveolar macrophages that were transcriptionally almost identical, with only 22 genes that could be linked to their origin. Underlining the physiological relevance of our findings, all transfer-derived alveolar macrophages self-maintained within the lungs for up to 1 year and durably prevented alveolar proteinosis. Thus, precursor origin does not affect the development of functional self-maintaining tissue-resident macrophages. CD45.1+CD45.2+ yolk sac macrophages, fetal liver monocytes, adult bone marrow monocytes or adult alveolar macrophages from the bronchoalveolar lavage were sorted from wild type CD45.1+CD45.2+ mice of indicated ages. From part of these samples RNA was isolated. The other part was transferred intranasally into the lungs of neonate Csf2rb-/- mice. 6 weeks post-transfer, transfer-derived CD45.1+CD45.2+ alveolar macrophages were sorted from the bronchoalveolar lavage. Wild type CD45.1+CD45.2 alveolar macrophages from the bronchoalveolar lavage of 6 week old mice were sorted as control. 36 samples (arrays) in total. RNA was isolated, amplified with Nugene pico kit, converted to cDNA and then hybridised on Affymetrix GeneChip Mouse Gene 1.0 ST Arrays.
Project description:Tissue-resident macrophages can derive from yolk sac macrophages, fetal liver monocytes or adult bone marrow monocytes. Whether these precursors can give rise to transcriptionally identical alveolar macrophages is unknown. Here, we transferred traceable yolk sac macrophages, fetal liver monocytes, adult bone marrow monocytes or adult alveolar macrophages as a control, into the empty alveolar macrophage niche of neonatal Csf2rb-/- mice. All precursors efficiently colonized the alveolar niche and generated alveolar macrophages that were transcriptionally almost identical, with only 22 genes that could be linked to their origin. Underlining the physiological relevance of our findings, all transfer-derived alveolar macrophages self-maintained within the lungs for up to 1 year and durably prevented alveolar proteinosis. Thus, precursor origin does not affect the development of functional self-maintaining tissue-resident macrophages.
Project description:Comparative genomic analysis of basal and LPS-induced expression patterns of bone marrow derived macrophages and bone marrow resident macrophages demonstrates completely divergent transcriptome profile and indicates/confirms the existance of two distinct monocyte/macrophage populations in murine bone marrow. Most resident tissue macrophages descent from embryonic precursors of the yolk sac but inflammatory and bone marrow (BM) macrophages are considered to develop from hematopoietic stem cells (HSCs) in the BM. We now identified a novel subpopulation of resident CD163+ macrophages in the BM which were phenotypically and functionally distinct from classical BM-derived macrophages. Bioinformatics analysis of transcriptoms indicated a unique immune-modulatory phenotype of CD163+ macrophages. Cell fate studies in Csf1rMer-iCre-Mer;RosaLSL-GFP mice demonstrated that resident CD163+ macrophages of the BM do not develop from HSCs but descent from embryonic progenitors in the yolk sac strictly dependent on transcription factor IRF8. In contrast to other yolk sac derived tissue macrophages CD163+ cells seem to play a relevant role in infections and sterile inflammation. IRF8-/- mice lacking this population are highly sensible to S. aureus infections. Thus, CD163 defines a macrophage population resident in the bone marrow but originating from yolk sac progenitors which exhibits immune-modulatory properties under different inflammatory conditions. We used quantitative RNA-seq to perform whole transcriptome analysis and compare the transcriptomes of resident CD163+ BM macrophages and classical CD163- BMDM in steady state and after LPS stimulation.
Project description:Tissue-resident macrophages such as microglia, Kupffer and Langerhans cells derive from Myb-independent yolk sac (YS) progenitors generated before the emergence of hematopoietic stem cells (HSCs). Myb-independent YS-derived resident macrophages self-renew locally, independently of circulating monocytes and HSCs. In contrast, adult blood monocytes as well as infiltrating, gut and dermal macrophages derive from Myb-dependent HSCs. These findings are derived from the mouse, using gene knock-outs and lineage tracing, but their applicability to human development has not been formally demonstrated. Here we use human induced pluripotent stem cells (iPSCs) as a tool to model human hematopoietic development. By using a CRISPR-Cas9 knock-out strategy we show that human iPSC-derived monocytes/macrophages develop in a MYB-independent, RUNX1 and SPI1 (PU.1)-dependent fashion. This result makes human iPSC-derived macrophages developmentally related to and a good model for MYB-independent tissue-resident macrophages such as alveolar and kidney macrophages, microglia, Kupffer and Langerhans cells.
Project description:Although classified as hematopoietic cells, tissue-resident macrophages are selfrenewing and maintained independently of adult hematopoiesis. While most macrophages originate from embryonic precursors that seed tissues prior to birth, their exact origin is unknown. Using an in utero macrophage depletion strategy and fatemapping of yolk sac (YS) and fetal liver (FL) hematopoiesis, we found that YS macrophages are the main precursors of microglia, while most other macrophages derive from fetal monocytes. Both YS macrophages and fetal monocytes arise from erythro-myeloid progenitors (EMP) generated in the YS. In the YS, EMP gave rise to macrophages without monocytic intermediates, while EMP seeding the FL upon the establishment of blood circulation acquired c-Myb expression and gave rise to fetal monocytes that then seed embryonic tissues to differentiate into macrophages. Thus, adult tissue-resident macrophages established from HSC-independent embryonic precursors arise from two different developmental programs. 12 samples of progenitors, monocytes or macrophages are analyzed from 2 to 4 replicate. Each replicate derived from at least 5 embryos or adult mice
Project description:Although classified as hematopoietic cells, tissue-resident macrophages are selfrenewing and maintained independently of adult hematopoiesis. While most macrophages originate from embryonic precursors that seed tissues prior to birth, their exact origin is unknown. Using an in utero macrophage depletion strategy and fatemapping of yolk sac (YS) and fetal liver (FL) hematopoiesis, we found that YS macrophages are the main precursors of microglia, while most other macrophages derive from fetal monocytes. Both YS macrophages and fetal monocytes arise from erythro-myeloid progenitors (EMP) generated in the YS. In the YS, EMP gave rise to macrophages without monocytic intermediates, while EMP seeding the FL upon the establishment of blood circulation acquired c-Myb expression and gave rise to fetal monocytes that then seed embryonic tissues to differentiate into macrophages. Thus, adult tissue-resident macrophages established from HSC-independent embryonic precursors arise from two different developmental programs.
Project description:Monocytes and macrophages constitute important components of immune system. Monocytes differentiate into macrophages following stimulation with cytokines and/or microbial molecule. Macrophages play central role in the maintenance of tissue homeostasis, development and its restoration after injury, as well as the initiation and resolution of innate and adaptive immunity. Though macrophages were long considered to be derived from differentiation of bone marrow monocytes, recent studies have proved that tissue resident macrophages are derived from yolk sac macrophages, fetal liver macrophages, can self-replicate from local proliferation. However, during homeostatic adaptations, injury and inflammation macrophages of different phenotypes can be recruited from the monocyte reservoirs of blood, spleen and bone marrow. Our studies show that Lysophosphatidic acid (LPA), a small lipid molecule converts monocytes into macrophages. We report the gene expression profile of primary mouse bone marrow monocytes treated for 5 days with LPA with respect to control monocytes.
Project description:Tissue resident macrophages can arise from either embryonic or adult hematopoiesis and play important roles in a wide range of biological processes, such as tissue remodeling during organogenesis, tissue homeostasis in the steady state, tissue repair following injury, and immune response to pathogens. Although the origins and tissue-specific functions of resident macrophages have been extensively studied in many other tissues, they are not well characterized in skeletal muscle. In the present study, we have characterized for the first time the ontogeny of skeletal muscle resident macrophages, showing evidence that they arise from both embryonic hematopoietic progenitors, including yolk sac primitive macrophages and fetal liver monocytes, and adult bone marrow hematopoietic stem cells. Single cell-based transcriptome analysis revealed that skeletal muscle resident macrophages were highly distinctive from resident macrophages in other tissues, expressing a specific set of transcription factors and containing functionally diverse subsets correlating to their origins. They appear more active in maintaining tissue homeostasis and promoting muscle growth and regeneration.
Project description:Self-renewing tissue-resident macrophages are thought to be exclusively derived from embryonic progenitors. However, whether circulating monocytes can also give rise to such macrophages has not been formally investigated. Here we use a new model of diphtheria toxin-mediated depletion of liver-resident Kupffer cells to generate niche availability and show that circulating monocytes engrafted in the liver, gradually adopt the transcriptional profile of their depleted counterparts and become long-lived self-renewing cells. Underlining the physiological relevance of our findings, circulating monocytes also contribute to the expanding pool of macrophages in the liver shortly after birth, when macrophage niches become available during normal organ growth. Thus, like embryonic precursors, monocytes can and do give rise to self-renewing tissue-resident macrophages if the niche is available to them. Clec4F+ Kupffer cells were isolated and sorted from livers from adult WT mice or KC-DTR or KC-DTR littermate control mice +/- 50ng DT at indicated timepoints. 19 samples (arrays) in total. RNA was isolated, amplified with Nugene pico kit, converted to cDNA and then hybridised on Affymetrix GeneChip Mouse Gene 1.0 ST Arrays.
Project description:White adipose tissue (WAT) stores energy in the form of lipids. WAT macrophages cause adipose tissue inflammation and insulin resistance when intake exceeds expenditures, but their contribution to homeostasis remain poorly understood. Here, we show that two populations, ã and ä, of TNF-producing bone marrow-derived monocytic cells are transiently recruited to damaged adipocytes and mediate insulin resistance. In contrast, we identify α/β yolk-sac derived resident macrophages that produce adipogenic growth factors, and form a niche required for adipogenesis as white adipocytes do not differentiate in their absence. Production of adipogenic growth factors by α/β macrophages increases with lipid storage, but they do not contribute to inflammation. Thus the molecular identities and functions of resident macrophages and BM-derived cells are specified by their lineage rather than diet variation. These results identify an essential function of WAT resident macrophages in adipogenesis and energy homeostasis, separate from inflammation mediated by the recruitment of inflammatory leukocytes.