Dynamics of macrophage polarization reveal new mechanism to inhibit IL-1Β release through pyrophosphates

Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK.
The EMBO Journal (Impact Factor: 10.43). 07/2009; 28(14):2114-27. DOI: 10.1038/emboj.2009.163
Source: PubMed

ABSTRACT In acute inflammation, extracellular ATP activates P2X(7) ion channel receptors (P2X(7)R) on M1 polarized macrophages to release pro-inflammatory IL-1beta through activation of the caspase-1/nucleotide-binding domain and leucine-rich repeat receptor containing pyrin domain 3 (NLRP3) inflammasome. In contrast, M2 polarized macrophages are critical to the resolution of inflammation but neither actions of P2X(7)R on these macrophages nor mechanisms by which macrophages switch from pro-inflammatory to anti-inflammatory phenotypes are known. Here, we investigated extracellular ATP signalling over a dynamic macrophage polarity gradient from M1 through M2 phenotypes. In macrophages polarized towards, but not at, M2 phenotype, in which intracellular IL-1beta remains high and the inflammasome is intact, P2X(7)R activation selectively uncouples to the NLRP3-inflammasome activation but not to upstream ion channel activation. In these intermediate M1/M2 polarized macrophages, extracellular ATP now acts through its pyrophosphate chains, independently of other purine receptors, to inhibit IL-1beta release by other stimuli through two independent mechanisms: inhibition of ROS production and trapping of the inflammasome complex through intracellular clustering of actin filaments.

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    • "reduce extracellular PP i to abnormally low levels and result in insufficient PP i substrate for TNAP to generate P i for normal mineralization (Anderson et al., 2005; Mackenzie et al., 2012). Along with a well-characterized role in bone and cartilage mineralization, recent data provide evidence for the involvement of NPP1 in generalized arterial calcification of infancy and pseudoxanthoma elasticum (Mackenzie et al., 2012; Rutsch et al., 2011), vascular smooth muscle cell calcification (Prosdocimo et al., 2009; Villa-Bellosta et al., 2011), inhibition of caspase-1 activation and interleukin-1b release in the course of macrophage differentiation into anti-inflammatory phenotype (Pelegrin et al., 2009), as well as inhibition of insulin signaling and glucose homeostasis by interacting with the insulin receptor and decreasing its b-subunit autophosphorylation (Abate et al., 2006; Mackenzie et al., 2012; Stefan et al., 2005). The latter observation is further ascertained by multiple linkage studies showing the association of the chromosome locus mapping ENPP1 to insulin resistance, hyperglyceridemia, childhood and adult obesity and increased risk of type 2 diabetes (Abate et al., 2006; Mackenzie et al., 2012). "
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    ABSTRACT: Abstract Extracellular nucleotides and nucleosides mediate diverse signaling effects in virtually all organs and tissues. Most models of purinergic signaling depend on functional interactions between distinct processes, including (i) the release of endogenous ATP and other nucleotides, (ii) triggering of signaling events via a series of nucleotide-selective ligand-gated P2X and metabotropic P2Y receptors as well as adenosine receptors and (iii) ectoenzymatic interconversion of purinergic agonists. The duration and magnitude of purinergic signaling is governed by a network of ectoenzymes, including the enzymes of the nucleoside triphosphate diphosphohydrolase (NTPDase) family, the nucleotide pyrophosphatase/phosphodiesterase (NPP) family, ecto-5'-nucleotidase/CD73, tissue-nonspecific alkaline phosphatase (TNAP), prostatic acid phosphatase (PAP) and other alkaline and acid phosphatases, adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP). Along with "classical" inactivating ectoenzymes, recent data provide evidence for the co-existence of a counteracting ATP-regenerating pathway comprising the enzymes of the adenylate kinase (AK) and nucleoside diphosphate kinase (NDPK/NME/NM23) families and ATP synthase. This review describes recent advances in this field, with special emphasis on purine-converting ectoenzymes as a complex and integrated network regulating purinergic signaling in such (patho)physiological states as immunomodulation, inflammation, tumorigenesis, arterial calcification and other diseases. The second part of this review provides a comprehensive overview and basic principles of major approaches employed for studying purinergic activities, including spectrophotometric Pi-liberating assays, high-performance liquid chromatographic (HPLC) and thin-layer chromatographic (TLC) analyses of purine substrates and metabolites, capillary electrophoresis, bioluminescent, fluorometric and electrochemical enzyme-coupled assays, histochemical staining, and further emphasizes their advantages, drawbacks and suitability for assaying a particular catalytic reaction.
    Critical Reviews in Biochemistry and Molecular Biology 11/2014; 49(6):473-97. DOI:10.3109/10409238.2014.953627 · 7.71 Impact Factor
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    • "I–K’, Heterogeneous distribution of actin proteins (phalloidin, green, in i and αSMA, red, in I–J) in pericytes plated on silicone plus human laminin. Wrinkles in magnified box (arrowheads, K’) are strongly correlated to αSMA expression (Ref [64] in Methods), as indicated in K. (L) Coronal section through the striatum (Str) of a brain pre-labeled for DLPs and perfused with black-Ink shows that DLPs (M, green, asterisks) express αSMA (magenta, arrowhead in magnification in N), which correlates with constricted segments (N’, yellow arrowhead) of a Ink-filled vessel (N’, white arrowhead). Nuclei (Hoechst) are in blue. "
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    ABSTRACT: Cancers likely originate in progenitor zones containing stem cells and perivascular stromal cells. Much evidence suggests stromal cells play a central role in tumor initiation and progression. Brain perivascular cells (pericytes) are contractile and function normally to regulate vessel tone and morphology, have stem cell properties, are interconvertible with macrophages and are involved in new vessel formation during angiogenesis. Nevertheless, how pericytes contribute to brain tumor infiltration is not known. In this study we have investigated the underlying mechanism by which the most lethal brain cancer, Glioblastoma Multiforme (GBM) interacts with pre-existing blood vessels (co-option) to promote tumor initiation and progression. Here, using mouse xenografts and laminin-coated silicone substrates, we show that GBM malignancy proceeds via specific and previously unknown interactions of tumor cells with brain pericytes. Two-photon and confocal live imaging revealed that GBM cells employ novel, Cdc42-dependent and actin-based cytoplasmic extensions, that we call flectopodia, to modify the normal contractile activity of pericytes. This results in the co-option of modified pre-existing blood vessels that support the expansion of the tumor margin. Furthermore, our data provide evidence for GBM cell/pericyte fusion-hybrids, some of which are located on abnormally constricted vessels ahead of the tumor and linked to tumor-promoting hypoxia. Remarkably, inhibiting Cdc42 function impairs vessel co-option and converts pericytes to a phagocytic/macrophage-like phenotype, thus favoring an innate immune response against the tumor. Our work, therefore, identifies for the first time a key GBM contact-dependent interaction that switches pericyte function from tumor-suppressor to tumor-promoter, indicating that GBM may harbor the seeds of its own destruction. These data support the development of therapeutic strategies directed against co-option (preventing incorporation and modification of pre-existing blood vessels), possibly in combination with anti-angiogenesis (blocking new vessel formation), which could lead to improved vascular targeting not only in Glioblastoma but also for other cancers.
    PLoS ONE 07/2014; 9(7):e101402. DOI:10.1371/journal.pone.0101402 · 3.23 Impact Factor
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    • "Although M1 and M2 polarisation represents either end of the polarisation scale, it is possible that macrophages can be activated towards a phenotype at any point between these two extremes. Evidence also suggests that macrophages are extremely plastic between activation states, switching rapidly from one to another, and fully reversible upon stimulation with a cytokine that has an opposite effect (Porcheray et al. 2005; Pelegrin and Surprenant 2009). "
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