Monocytes differentiate into macrophages or dendritic cells along two alternative paths controlled by distinct regulatory networks
Ontology highlight
ABSTRACT: During inflammation, monocytes differentiate within tissues into macrophages (mo-Mac) or dendritic cells (mo-DC). Whether these two progenies derive from alternative differentiation pathways or represent different stages along a continuum remains unclear. Here we addressed this question using temporal single-cell RNA sequencing in an in vitro model allowing the simultaneous differentiation of human mo-Mac and mo-DC. We evidenced divergent differentiation paths, with a fate decision occurring within the first 24 hours. We confirmed this result in vivo using a mouse model of peritonitis. Using a computational approach, we identified candidate transcription factors potentially involved in monocyte fate commitment. We demonstrated that IRF1 is necessary for mo-Mac differentiation, independently of its transcriptional control of interferon-stimulated genes. In addition, we validated the transcription factors ZNF366 and MAFF as regulators of mo-DC development. Our results indicate that mo-Mac and mo-DC represent two alternative cell fates requiring distinct transcription factors for their differentiation.
Project description:DC-SIGN+ monocyte-derived dendritic cells (mo-DCs) play important roles in bacterial infections and inflammatory diseases, but the factors regulating their differentiation and proinflammatory status remain poorly defined. Here, we identify a micro-RNA, miR-181a, and a molecular mechanism that simultaneously regulate the acquisition of DC-SIGN+ expression and the activation state of DC-SIGN+ mo-DCs. Specifically, we show that miR-181a promotes DC-SIGN expression during terminal mo-DC differentiation and limits its sensitivity and responsiveness to TLR triggering and CD40 ligation. Mechanistically, miR-181a sustains ERK-MAPK signaling in mo-DCs, thereby enabling the maintenance of high levels of DC-SIGN and a high activation threshold. Low miR-181a levels during mo-DC differentiation, induced by inflammatory signals, do not support the high phospho-ERK signal transduction required for DC-SIGNhi mo-DCs and lead to development of proinflammatory DC-SIGNlo/- mo-DCs. Collectively, our study demonstrates that high DC-SIGN expression levels and a high activation threshold in mo-DCs are linked and simultaneously maintained by miR-181a.
Project description:The molecular requirements that guide the differentiation of monocytes into macrophages or monocyte-derived dendritic cells (Mo-DCs) are poorly understood. Here, we demonstrate that the nuclear orphan receptor NR4A3 guides monocyte fate and is essential for Mo-DC differentiation. Nr4a3-/- mice are impaired in the in vivo generation of DC-SIGN+ Mo-DCs following LPS stimulation and, as such, are defective at priming a CD8+ T cell response to gram negative bacteria. We also demonstrate that NR4A3 is an essential downstream effector of IRF4 during in vitro differentiation of Mo-DCs with GM-CSF and IL-4 and that, in absence of NR4A3, monocytes are diverted to macrophages. Our transcriptomic analysis of the genes regulated by NR4A3 reveals that the acquisition of the Mo-DC differentiation program is intertwined with the acquisition of a migratory signature. Furthermore, NR4A3 is critical for steady-state migration of non-lymphoid tissue conventional DCs to lymph nodes. Altogether, our results highlight a unique role for NR4A3 in Mo-DC differentiation and in the acquisition of migratory properties.
Project description:Peripheral blood monocytes are the starting material utilized in conventional dendritic cell (DC) vaccination for the treatment of a broad range of malignancies. While the use of cytokines and growth factors to polarize monocyte-derived DC to distinct phenotypes is well-established, little is known about the contributions of distinct human monocyte subsets to monocyte-derived DC function and patient responses to vaccination. To investigate the status of monocyte subsets in cancer patients and following culture into DC, we isolated classical (C-Mo), intermediate (I-Mo), and non-classical (NC-Mo) from the peripheral blood of renal cell carcinoma (RCC) patients prior to DC vaccination (NCT00085436) and from anonymous healthy donors. Patients treated with DC vaccination who were long term survivors (>100 months survival) had a unique monocyte signature with a two-fold higher percentage of NC-Mo in pretreatment peripheral blood compared to other RCC patients. RCC patient monocytes from each subset were transcriptionally distinct from healthy donor monocytes. Further transcriptional analysis determined that each monocyte subset was characterized by a discrete gene expression profile before and after DC maturation. Phenotypic analysis showed that DC derived from NC-Mo expressed higher levels of CD80, CD83, CD86, HLA-DR, and CD40 compared to DC originating from C-Mo and secreted increased amounts of IL-12p70 following CD40L stimulation. Collectively, these findings establish that DC derived from NC-Mo are potent antigen presenting cells and provide the foundation for future vaccination strategies that enrich NC-Mo prior to DC maturation.
Project description:Peripheral blood monocytes are the starting material utilized in conventional dendritic cell (DC) vaccination for the treatment of a broad range of malignancies. While the use of cytokines and growth factors to polarize monocyte-derived DC to distinct phenotypes is well-established, little is known about the contributions of distinct human monocyte subsets to monocyte-derived DC function and patient responses to vaccination. To investigate the status of monocyte subsets in cancer patients and following culture into DC, we isolated classical (C-Mo), intermediate (I-Mo), and non-classical (NC-Mo) from the peripheral blood of renal cell carcinoma (RCC) patients prior to DC vaccination (NCT00085436) and from anonymous healthy donors. Patients treated with DC vaccination who were long term survivors (>100 months survival) had a unique monocyte signature with a two-fold higher percentage of NC-Mo in pretreatment peripheral blood compared to other RCC patients. RCC patient monocytes from each subset were transcriptionally distinct from healthy donor monocytes. Further transcriptional analysis determined that each monocyte subset was characterized by a discrete gene expression profile before and after DC maturation. Phenotypic analysis showed that DC derived from NC-Mo expressed higher levels of CD80, CD83, CD86, HLA-DR, and CD40 compared to DC originating from C-Mo and secreted increased amounts of IL-12p70 following CD40L stimulation. Collectively, these findings establish that DC derived from NC-Mo are potent antigen presenting cells and provide the foundation for future vaccination strategies that enrich NC-Mo prior to DC maturation.
Project description:Peripheral blood monocytes are the starting material utilized in conventional dendritic cell (DC) vaccination for the treatment of a broad range of malignancies. While the use of cytokines and growth factors to polarize monocyte-derived DC to distinct phenotypes is well-established, little is known about the contributions of distinct human monocyte subsets to monocyte-derived DC function and patient responses to vaccination. To investigate the status of monocyte subsets in cancer patients and following culture into DC, we isolated classical (C-Mo), intermediate (I-Mo), and non-classical (NC-Mo) from the peripheral blood of renal cell carcinoma (RCC) patients prior to DC vaccination (NCT00085436) and from anonymous healthy donors. Patients treated with DC vaccination who were long term survivors (>100 months survival) had a unique monocyte signature with a two-fold higher percentage of NC-Mo in pretreatment peripheral blood compared to other RCC patients. RCC patient monocytes from each subset were transcriptionally distinct from healthy donor monocytes. Further transcriptional analysis determined that each monocyte subset was characterized by a discrete gene expression profile before and after DC maturation. Phenotypic analysis showed that DC derived from NC-Mo expressed higher levels of CD80, CD83, CD86, HLA-DR, and CD40 compared to DC originating from C-Mo and secreted increased amounts of IL-12p70 following CD40L stimulation. Collectively, these findings establish that DC derived from NC-Mo are potent antigen presenting cells and provide the foundation for future vaccination strategies that enrich NC-Mo prior to DC maturation.
Project description:Fungal pathogens are underappreciated causes of significant morbidity and mortality worldwide. In previous studies we determined that a heat-killed, Cryptococcus neoformans fbp1-deficient strain (HK-fbp1) is a potent vaccine candidate. We determined that vaccination with HK-fbp1 confers protective immunity against lethal Cryptococcosis in an interferon γ (IFNγ)-dependent manner. In this study, we set out to uncover cellular sources and relevant targets of the protective effects of IFNγ in response to the HK-fbp1 vaccine. We found that early IFNγ production peaks at day 3 and that monocytes and neutrophils are important sources of this cytokine after vaccination. Neutralization of IFNγ at day 3 results in impaired CCR2+ monocyte recruitment and reduced differentiation into monocyte-derived dendritic cells (Mo-DC). In turn, depletion of CCR2+ cells prior to immunization results in impaired activation of IFNγ-producing CD4 and CD8 T cells. Thus, monocytes are important targets of innate IFNγ and help promote further IFNγ production by lymphocytes. We employed monocyte-fate mapper and conditional STAT1 knockout mice to uncover that STAT1 activation in CD11c+ cells, including alveolar macrophages, Mo-DCs, and monocyte-derived macrophages (Mo-Mac) is essential for HK-fbp1 vaccine-induced protection. Altogether, our aggregate findings suggest critical roles for innate cells as orchestrators of vaccine-induced protection against Cryptococcus infection.
Project description:MafF-/-: MafG+/+: MafK-/- mice are viable, while MafF-/-: MafG-/-: MafK-/- mice are embryonic lethal. To get an insight into the cause of the lethality of small Maf triple knockout mice, transcriptome analysis was performed using whole embyos of MafF-/-: MafG-/-: MafK-/- at E10.5 and those of MafF-/-: MafG+/+: MafK-/- at E9.5 or E10.5. Because MafF-/-: MafG-/-: MafK-/- embryos exhibit growth retardation, the gene expression profile of MafF-/-: MafG-/-: MafK-/- embryos at E10.5 was compared with that of MafF-/-: MafG+/+: MafK-/- embyos at E9.5. The gene expression profile of MafF-/-: MafG+/+: MafK-/- embryos at E10.5 was also examined as an alternative control. Total RNA was prepared from pooled three embryos for each sample.
Project description:Monocytes can differentiate into macrophages or dendritic cells. When treated with granulocyte-macrophage colony-stimulating factor (GM-CSF) monocytes differentiate into macrophage-like cells. Here, we report that pharmacological blockade of the nuclear receptor PPARγ in monocytes turns GM-CSF into a potent inducer of dendritic cell (Mo-DC) differentiation. Remarkably, simultaneous blockade of PPARγ and mTORC1 in the presence of GM-CSF promoted the differentiation of Mo-DCs with a stronger phenotypic stability and immunogenic profile when compared with canonical Mo-DCs differentiated by treatment with GM-CSF and IL-4. Moreover, and in contrast with the observations made with GM-CSF and IL-4, blockade of PPARγ and mTORC1 was shown to be able to induce the differentiation of monocyte-derived macrophages (Mo-Macs) into Mo-DCs. Transcriptional profiling performed at either early time points, as well as at the end of the differentiation process, revealed marked differences in the gene expression signature between Mo-DCs induced by GM-CSF and IL-4 and Mo-DCs induced by GM-CSF in the presence of PPARγ and/or mTORC1 inhibitors, thus suggesting diverging differentiation pathways. Our observations might contribute, not only to a better understanding of the mechanisms involved in Mo-DCs differentiation but also to improving the efficacy of both, DC vaccines and therapies focusing on the modulation of myeloid cell functions.