Differential Expression of NLRP3 among Hematopoietic Cells

Department of Biochemistry, University of Lausanne, 1066 Epalinges, Switzerland.
The Journal of Immunology (Impact Factor: 5.36). 02/2011; 186(4):2529-34. DOI: 10.4049/jimmunol.1002720
Source: PubMed

ABSTRACT Although the importance of the NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome in health and disease is well appreciated, a precise characterization of NLRP3 expression is yet undetermined. To this purpose, we generated a knock-in mouse in which the Nlrp3 coding sequence was substituted for the GFP (enhanced GFP [egfp]) gene. In this way, the expression of eGFP is driven by the endogenous regulatory elements of the Nlrp3 gene. In this study, we show that eGFP expression indeed mirrors that of NLRP3. Interestingly, splenic neutrophils, macrophages, and, in particular, monocytes and conventional dendritic cells showed robust eGFP fluorescence, whereas lymphoid subsets, eosinophils, and plasmacytoid dendritic cells showed negligible eGFP levels. NLRP3 expression was highly inducible in macrophages, both by MyD88- and Trif-dependent pathways. In vivo, when mice were challenged with diverse inflammatory stimuli, differences in both the number of eGFP-expressing cells and fluorescence intensity were observed in the draining lymph node. Thus, NLRP3 levels at the site of adaptive response initiation are controlled by recruitment of NLRP3-expressing cells and by NLRP3 induction.

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Available from: Kate Schroder, Apr 22, 2015
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    • "As demonstrated, these key proteins are identified as NLRP3 (for nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3) ASC (apoptosis associated speck-like protein containing a CARD), and procaspase-1 (Figure 1). NLRP3 is expressed predominantly in circulating monocytes and tissue macrophages (Guarda et al., 2011). The NLRP3 inflammasome components contain conserved protein domains and interaction of these domains on inflammasome proteins (i.e., homotypic protein–protein interactions ) leads to inflammasome assembly. "
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    ABSTRACT: Over the recent past, the importance of aberrant immune cell activation as one of the contributing mechanisms to the development of insulin-resistance and type 2 diabetes (T2D) has been recognized. Among the panoply of pro-inflammatory cytokines that are linked to chronic metabolic diseases, new data suggests that interleukin-1β (IL-1β) may play an important role in initiating and sustaining inflammation-induced organ dysfunction in T2D. Therefore, factors that control secretion of bioactive IL-1β have therapeutic implications. In this regard, the identification of multiprotein scaffolding complexes, "inflammasomes," has been a great advance in our understanding of this process. The secretion of bioactive IL-1β is predominantly controlled by activation of caspase-1 through assembly of a multiprotein scaffold, "inflammasome" that is composed of NLRP3 (nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3) ASC (apoptosis associated speck-like protein containing a CARD) and procaspase-1. The NLRP3 inflammasome appears to be an important sensor of metabolic dysregulation and controls obesity-associated insulin resistance and pancreatic beta cell dysfunction. Initial clinical "proof of concept" studies suggest that blocking IL-1β may favorably modulate factors related to development and treatment of T2D. However, this potential therapeutic approach remains to be fully substantiated through phase-II clinical studies. Here, we outline the new immunological mechanisms that link metabolic dysfunction to the emergence of chronic inflammation and discuss the opportunities and challenges of future therapeutic approaches to dampen NLRP3 inflammasome activation or IL-1β signaling for controlling type 2 diabetes.
    Frontiers in Immunology 03/2013; 4:50. DOI:10.3389/fimmu.2013.00050
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    • "For example the ability of inflammasomes to influence autoinflammatory pathogenesis in cell types other than macrophages and dendritic cells has not been studied in detail. Multiple immune and organ-specific cell types express NLRs and inflammasomeassociated proteins (Guarda et al., 2011b; Kufer and Sansonetti, 2011). Investigation of their contribution to disease should provide novel insight. "
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    ABSTRACT: Inflammation plays vital roles in protective responses against pathogens and tissue repair, however, improper resolution of inflammatory networks is centrally involved in the pathogenesis of many acute and chronic diseases. Extensive advances have been made in recent years to define the inflammatory processes that are required for pathogen clearance, however, in comparison, less is known about the regulation of inflammation in sterile settings. Over the past decade non-communicable chronic diseases that are potentiated by sterile inflammation have replaced infectious diseases as the major threat to global human health. Thus, improved understanding of the sterile inflammatory process has emerged as one of the most important areas of biomedical investigation during our time. In this review we highlight the central role that interleukin-1 family cytokines play in sterile inflammatory diseases.
    Frontiers in Immunology 10/2012; 3:315. DOI:10.3389/fimmu.2012.00315
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    • "reduction in pro-inflammatory cytokines observed in Nlrp3-deficient mice suggests that additional proteins in the NLR family may contribute to the response to both ozone and hyaluronan. While ASC and caspase1 are ubiquitously expressed in many cell types, Nlrp3 is primarily expressed in myeloid cells (Guarda et al. 2011). NLR proteins expressed in nonmyeloid cells may prove important. "
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    ABSTRACT: Background: The role of the Nlrp3 inflammasome in nonallergic airway hyperresponsiveness (AHR) has not previously been reported. Recent evidence supports both interleukin (IL) 1β and short fragments of hyaluronan (HA) as contributors to the biological response to inhaled ozone. Objective: Because extracellular secretion of IL-1β requires activation of the inflammasome, we investigated the role of the inflammasome proteins ASC, caspase1, and Nlrp3 in the biological response to ozone and HA. Methods: C57BL/6J wild-type mice and mice deficient in ASC, caspase1, or Nlrp3 were exposed to ozone (1 ppm for 3 hr) or HA followed by analysis of airway resistance, cellular inflammation, and total protein and cytokines in bronchoalveolar lavage fluid (BALF). Transcription levels of IL-1β and IL-18 were determined in two populations of lung macrophages. In addition, we examined levels of cleaved caspase1 and cleaved IL-1β as markers of inflammasome activation in isolated alveolar macrophages harvested from BALF from HA-treated mice. Results: We observed that genes of the Nlrp3 inflammasome were required for development of AHR following exposure to either ozone or HA fragments. These genes are partially required for the cellular inflammatory response to ozone. The expression of IL-1β mRNA in alveolar macrophages was up-regulated after either ozone or HA challenge and was not dependent on the Nlrp3 inflammasome. However, soluble levels of IL-1β protein were dependent on the inflammasome after challenge with either ozone or HA. HA challenge resulted in cleavage of macrophage-derived caspase1 and IL-1β, suggesting a role for alveolar macrophages in Nlrp3-dependent AHR. Conclusions: The Nlrp3 inflammasome is required for the development of ozone-induced reactive airways disease.
    Environmental Health Perspectives 09/2012; 120(12). DOI:10.1289/ehp.1205188 · 7.03 Impact Factor
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