0000000000411256
AUTHOR
Antonio Sica
Tolerance and M2 (alternative) macrophage polarization are related processes orchestrated by p50 nuclear factor {kappa}B.
Cells of the monocyte-macrophage lineage play a central role in the orchestration and resolution of inflammation. Plasticity is a hallmark of mononuclear phagocytes, and in response to environmental signals these cells undergo different forms of polarized activation, the extremes of which are called classic or M1 and alternative or M2. NF-kappaB is a key regulator of inflammation and resolution, and its activation is subject to multiple levels of regulation, including inhibitory, which finely tune macrophage functions. Here we identify the p50 subunit of NF-kappaB as a key regulator of M2-driven inflammatory reactions in vitro and in vivo. p50 NF-kappaB inhibits NF-kappaB-driven, M1-polariz…
RORC1 Regulates Tumor-Promoting "Emergency" Granulo-Monocytopoiesis
Cancer-driven granulo-monocytopoiesis stimulates expansion of tumor promoting myeloid populations, mostly myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs). We identified subsets of MDSCs and TAMs based on the expression of retinoic-acid-related orphan receptor (RORC1/RORγ) in human and mouse tumor bearers. RORC1 orchestrates myelopoiesis by suppressing negative (Socs3 and Bcl3) and promoting positive (C/EBPβ) regulators of granulopoiesis, as well as the key transcriptional mediators of myeloid progenitor commitment and differentiation to the monocytic/macrophage lineage (IRF8 and PU.1). RORC1 supported tumor-promoting innate immunity by protecting MDSCs from …
SPARC is a new myeloid-derived suppressor cell marker licensing suppressive activities
Myeloid-derived suppressor cells (MDSC) are well-known key negative regulators of the immune response during tumor growth, however scattered is the knowledge of their capacity to influence and adapt to the different tumor microenvironments and of the markers that identify those capacities. Here we show that the secreted protein acidic and rich in cysteine (SPARC) identifies in both human and mouse MDSC with immune suppressive capacity and pro-tumoral activities including the induction of epithelial-to-mesenchymal transition (EMT) and angiogenesis. In mice the genetic deletion of SPARC reduced MDSC immune suppression and reverted EMT. Sparc−/− MDSC were less suppressive overall and the granu…
Tolerance and M2 (alternative) macrophage polarization are related processes orchestrated by p50 nuclear factor κB
Cells of the monocyte-macrophage lineage play a central role in the orchestration and resolution of inflammation. Plasticity is a hallmark of mononuclear phagocytes, and in response to environmental signals these cells undergo different forms of polarized activation, the extremes of which are called classic or M1 and alternative or M2. NF-kappaB is a key regulator of inflammation and resolution, and its activation is subject to multiple levels of regulation, including inhibitory, which finely tune macrophage functions. Here we identify the p50 subunit of NF-kappaB as a key regulator of M2-driven inflammatory reactions in vitro and in vivo. p50 NF-kappaB inhibits NF-kappaB-driven, M1-polariz…
Tumor-Derived Prostaglandin E2 Promotes p50 NF-κB-Dependent Differentiation of Monocytic MDSCs
Abstract Myeloid-derived suppressor cells (MDSC) include immature monocytic (M-MDSC) and granulocytic (PMN-MDSC) cells that share the ability to suppress adaptive immunity and to hinder the effectiveness of anticancer treatments. Of note, in response to IFNγ, M-MDSCs release the tumor-promoting and immunosuppressive molecule nitric oxide (NO), whereas macrophages largely express antitumor properties. Investigating these opposing activities, we found that tumor-derived prostaglandin E2 (PGE2) induces nuclear accumulation of p50 NF-κB in M-MDSCs, diverting their response to IFNγ toward NO-mediated immunosuppression and reducing TNFα expression. At the genome level, p50 NF-κB promoted binding …
Nicotinamide Phosphoribosyltransferase Acts as a Metabolic Gate for Mobilization of Myeloid-Derived Suppressor Cells
Abstract Cancer induces alteration of hematopoiesis to fuel disease progression. We report that in tumor-bearing mice the macrophage colony-stimulating factor elevates the myeloid cell levels of nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in the NAD salvage pathway, which acts as negative regulator of the CXCR4 retention axis of hematopoietic cells in the bone marrow. NAMPT inhibits CXCR4 through a NAD/Sirtuin 1–mediated inactivation of HIF1α-driven CXCR4 gene transcription, leading to mobilization of immature myeloid-derived suppressor cells (MDSC) and enhancing their production of suppressive nitric oxide. Pharmacologic inhibition or myeloid-specific ablation …