Project description:We recently reported that some cancers induce accumulation of bone marrow (BM) B-cell precursors in the spleen to convert them into metastasis-promoting, immunosuppressive B cells. Here, using various murine tumor models and samples from humans with breast and ovarian cancers, we provide evidence that cancer cells also coopt differentiation of the extranodal B-cell precursors to generate macrophages (termed B-MF). We link the trans-differentiation to a small subset of CSF1R+ Pax5Lo cells within BM pro-/pre-B and immature B cells and cancer-secreted M-CSF that downregulates Pax5 via CSF1R signaling. Thus, cancer generates tumor-associated macrophages (TAM) from B-cell precursors besides their primary source, monocytes. Based on their differences from monocyte-derived TAM, such as a superb ability to induce FoxP3+ Tregs, suppress proliferation of T cells and more efficiently phagocytize apoptotic cells, we propose that cancer generates B-MF to mediate cancer escape.
Project description:We recently reported that some cancers induce accumulation of bone marrow (BM) B-cell precursors in the spleen to convert them into metastasis-promoting, immunosuppressive B cells. Here, using various murine tumor models and samples from humans with breast and ovarian cancers, we provide evidence that cancer cells also coopt differentiation of the extranodal B-cell precursors to generate macrophages (termed B-MF). We link the trans-differentiation to a small subset of CSF1R+ Pax5Lo cells within BM pro-/pre-B and immature B cells and cancer-secreted M-CSF that downregulates Pax5 via CSF1R signaling. Thus, cancer generates tumor-associated macrophages (TAM) from B-cell precursors besides their primary source, monocytes. Based on their differences from monocyte-derived TAM, such as a superb ability to induce FoxP3+ Tregs, suppress proliferation of T cells and more efficiently phagocytize apoptotic cells, we propose that cancer generates B-MF to mediate cancer escape.
Project description:Cancer actively uses B cells to promote its progression and metastasis. For example, it causes accumulation of bone marrow (BM) B-cell precursors in spleen to convert into immunosuppressive Breg cells. Here, we provide evidence that cancer also coopts differentiation BM CSF1R+ Pax5Lo B-cell precursors to generate macrophages (termed B-MF cells). To do this, cancer uses CSF1 to trigger Csf1r signaling and downregulate PAX5 in B-cell precursors by activating FOXO1. Although tumor-associated macrophages (TAMs) are primarily derived from BM monocytes, our data suggest that some of them may have B-cell origin. Unlike monocyte-derived TAMs, B-MF exhibit a higher M2 polarization, more efficiently phagocytize apoptotic cells, induce FoxP3+ Tregs and suppress T cells activity. We propose that the cancer-B-MF axis is a novel immune escape pathway, thus a therapeutic target.
Project description:This study aimed to elucidate the mechanism by which exosomes from bone-metastatic Lewis lung carcinoma (BM-LLC) cells promote osteolytic metastasis. We performed RNA-seq on mouse RAW264.7 macrophages (osteoclast precursors) treated with exosomes derived from either non-metastatic (NC-LLC) or bone-metastatic (BM-LLC) Lewis lung carcinoma cells. The goal was to identify differentially expressed genes and key regulatory pathways involved in exosome-induced osteoclast differentiation. Integrated analysis with small RNA sequencing data from the exosomes identified the miR-484-PECAM1 axis as a critical driver of this process. Our findings reveal that BM-LLC exosomes deliver miR-484 to recipient macrophages, repress PECAM1 expression, and subsequently upregulate osteoclastogenic markers (TRAP, CTSK, RANKL) and master transcription factors (NFATc1, c-Fos), thereby reprogramming osteoclastogenesis and driving bone destruction.
Project description:A major population of placenta macrophages represented throughout the pregnancy consists of CD14+ macrophages, but their characteristics remain badly understood. Here we purified from placentas at term CD14+ macrophages using positive selection. The phenotyping of CD14+ macrophages performed using flow cytometry revealed that placenta CD14+ macrophages expressed a series of markers distinct of those of circulating monocytes monocyte-derived macrophages. Placenta CD14+ macrophages spontaneously matured in multinucleated giant cells (MGCs) as demonstrated by size, number of nuclei display and specific cytoskeleton organization. Placenta CD14+ macrophages and MGCs were phagocytic cells but the potential of MGCs to mount an inflammatory response was lower than that of their precursors. Placenta CD14+ macrophages and MGCs stimulated with interferon and interleukin-4 were not polarized into typical M1 or M2 profiles. Placenta macrophages exhibited specific activation transcriptional programs. Indeed, principal component analysis and hierarchical clustering show that placental macrophages formed a distinct group from circulating monocytes and monocyte-derived macrophages. Among placenta macrophages, it was also possible to distinguish CD14+ macrophages and MGCs. In addition, networks based on gene interactions were clearly different in CD14+ macrophages and MGCs. Finally, the microenvironment of placenta CD14+ macrophages governs their differentiation into MGCs because CD14+ macrophages incubated with trophoblasts exhibited exarcerbated characteristics of MGCs and because the co-incubation of circulating monocytes from working women with trophoblast supernatants resulted into the formation of MGCs whereas monocytes from non-pregnant women incubated with trophoblast supernatants did not differentiate into MGCs. Taken together, these results clearly demonstrated specific feaures of placenta CD14+ macrophages. Three replicates of each of the following: 1. Placental macrophages just after isolation (CD14+ macrophages) 2. Placental macrophages after 9 days in culture (MGCs) 3. CD14+ cells isolated from PBMC which are extracted from the whole human blood of healthy donors (Monocytes) 4. Macrophages derived from monocytes (MDMs)
Project description:Monocytes are circulating short-lived macrophage precursors that are recruited on demand from the blood to sites of inflammation and challenge. In steady state, classical monocytes give rise to vasculature-resident cells that patrol the luminal side of the endothelium. In addition, classical monocytes feed macrophage compartments of selected organs, including barrier tissues, such as the skin and intestine, as well as the heart. Monocyte differentiation under conditions of inflammation has been studied in considerable detail. In contrast, monocyte differentiation under non-inflammatory conditions remains less well understood. Here we took advantage of a combination of cell ablation and precursor engraftment to investigate the generation of gut macrophages from monocytes. Collectively, we identify factors associated with the gradual adaptation of monocytes to tissue residency. Moreover, comparison of monocyte differentiation into the colon and ileum-resident macrophages revealed the graduated acquisition of gut segment-specific gene expression signatures.