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Lambeth JD, Neish AS. Nox enzymes and new thinking on reactive oxygen: a double-edged sword revisited. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2013; 9:119-45. [PMID: 24050626 DOI: 10.1146/annurev-pathol-012513-104651] [Citation(s) in RCA: 346] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Reactive oxygen species (ROS) are a chemical class of molecules that have generally been conceptualized as deleterious entities, albeit ones whose destructive properties could be harnessed as antimicrobial effector functions to benefit the whole organism. This appealingly simplistic notion has been turned on its head in recent years with the discovery of the NADPH oxidases, or Noxes, a family of enzymes dedicated to the production of ROS in a variety of cells and tissues. The Nox-dependent, physiological generation of ROS is highly conserved across virtually all multicellular life, often as a generalized response to microbes and/or other exogenous stressors. This review discusses the current knowledge of the role of physiologically generated ROS and the enzymes that form them in both normal biology and disease.
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Affiliation(s)
- J David Lambeth
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia 30322;
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52
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Álvarez S, Muñoz-Fernández MÁ. TNF-Α may mediate inflammasome activation in the absence of bacterial infection in more than one way. PLoS One 2013; 8:e71477. [PMID: 23940760 PMCID: PMC3737100 DOI: 10.1371/journal.pone.0071477] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 06/29/2013] [Indexed: 01/27/2023] Open
Abstract
Members of the mammalian nucleotide binding domain, leucine-rich repeat (LRR)-containing receptor family of proteins are key modulators of innate immunity regulating inflammation. To date, microbial pathogen-associated molecules and toxins have been identified as key triggers of activation of inflammasomes. However, recently, environmental, and neurodegenerative stimuli have been identified that lead to IL-1β release by means of inflammasomes. IL-1β plays a crucial role during brain inflammation, and caspase-1 appears to be a key modulator of IL-1β bioactivity and the consequent transcriptional regulation of gene expression within the brain during inflammation. We show here that exposure of a human neuroblastoma cell line (SK-N-MC cells) to TNF-α promotes ROS-mediated caspase-1 activation and IL-1β secretion. The involvement of NF-κB in the regulation of IL-1β synthesis is investigated through specific inhibition of this transcription factor. The effect of TNF-α was abolished in the presence of ROS inhibitors as NAC, or DPI. Remarkably, SK-N-MC cells do not respond to ATP stimulation in spite of P2X7R expression. These results provide a mechanism by which danger signals and particulate matter mediate inflammation via the inflammasome in the absence of microbial infection.
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Affiliation(s)
- Susana Álvarez
- Laboratorio InmunoBiología Molecular, Hospital General Universitario Gregorio Marañón, Madrid, Spain
- Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
| | - Ma Ángeles Muñoz-Fernández
- Laboratorio InmunoBiología Molecular, Hospital General Universitario Gregorio Marañón, Madrid, Spain
- Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
- Networking Research Center on Bioengineering, Biomaterials and Nanomedicine, Madrid, Spain
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53
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Kotsias F, Hoffmann E, Amigorena S, Savina A. Reactive oxygen species production in the phagosome: impact on antigen presentation in dendritic cells. Antioxid Redox Signal 2013; 18:714-29. [PMID: 22827577 DOI: 10.1089/ars.2012.4557] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
SIGNIFICANCE The NADPH oxidase 2 (NOX2) is known to play a major role in innate immunity for several decades. Phagocytic cells provide host defense by ingesting microbes and destroy them by different mechanisms, including the generation of reactive oxygen species (ROS) by NOX2, a process known as oxidative burst. The phagocytic pathway of dendritic cells (DCs), highly adapted to antigen processing, has been shown to display remarkable differences compared to other phagocytes. Contrary to macrophages and neutrophils, the main function of DC phagosomes is antigen presentation rather than pathogen killing or clearance of cell debris. RECENT ADVANCES In the last few years, it became clear that NOX2 is also involved in the establishment of adaptive immunity. Several studies support the idea of a relationship between antigen presentation and the level of antigen degradation, the latter one being regulated by the pH and ROS within phagosomes. CRITICAL ISSUES The regulation of phagosomal pH exerted by NOX2, and thereby of the efficacy of antigen cross-presentation in DCs, represents a clear illustration of how NOX2 can influence CD8(+) T lymphocyte responses. In this review, we want to put emphasis on the relationship between ROS generation and antigen processing and presentation, since there is growing evidence that the low levels of ROS generated by DCs play an important role in these processes. FUTURE DIRECTIONS In the next years, it will be interesting to unravel possible mechanisms involved and to find other possible connections between NOX family members and adaptive immune responses.
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Wu Y, Lu J, Antony S, Juhasz A, Liu H, Jiang G, Meitzler JL, Hollingshead M, Haines DC, Butcher D, Roy K, Doroshow JH. Activation of TLR4 is required for the synergistic induction of dual oxidase 2 and dual oxidase A2 by IFN-γ and lipopolysaccharide in human pancreatic cancer cell lines. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2013; 190:1859-72. [PMID: 23296709 PMCID: PMC3563939 DOI: 10.4049/jimmunol.1201725] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Pancreatitis is associated with release of proinflammatory cytokines and reactive oxygen species and plays an important role in the development of pancreatic cancer. We recently demonstrated that dual oxidase (Duox)2, an NADPH oxidase essential for reactive oxygen species-related, gastrointestinal host defense, is regulated by IFN-γ-mediated Stat1 binding to the Duox2 promoter in pancreatic tumor lines. Because LPS enhances the development and invasiveness of pancreatic cancer in vivo following TLR4-related activation of NF-κB, we examined whether LPS, alone or combined with IFN-γ, regulated Duox2. We found that upregulation of TLR4 by IFN-γ in BxPC-3 and CFPAC-1 pancreatic cancer cells was augmented by LPS, resulting in activation of NF-κB, accumulation of NF-κB (p65) in the nucleus, and increased binding of p65 to the Duox2 promoter. TLR4 silencing with small interfering RNAs, as well as two independent NF-κB inhibitors, attenuated LPS- and IFN-γ-mediated Duox2 upregulation in BxPC-3 cells. Induction of Duox2 expression by IFN-γ and LPS may result from IFN-γ-related activation of Stat1 acting in concert with NF-κB-related upregulation of Duox2. Sustained extracellular accumulation of H(2)O(2) generated by exposure to both LPS and IFN-γ was responsible for an ∼50% decrease in BxPC-3 cell proliferation associated with a G(1) cell cycle block, apoptosis, and DNA damage. We also demonstrated upregulation of Duox expression in vivo in pancreatic cancer xenografts and in patients with chronic pancreatitis. These results suggest that inflammatory cytokines can interact to produce a Duox-dependent pro-oxidant milieu that could increase the pathologic potential of pancreatic inflammation and pancreatic cancer cells.
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Affiliation(s)
- Yongzhong Wu
- Laboratory of Molecular Pharmacology of the Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Jiamo Lu
- Laboratory of Molecular Pharmacology of the Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Smitha Antony
- Laboratory of Molecular Pharmacology of the Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Agnes Juhasz
- Laboratory of Molecular Pharmacology of the Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Han Liu
- Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Guojian Jiang
- Laboratory of Molecular Pharmacology of the Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Jennifer L. Meitzler
- Laboratory of Molecular Pharmacology of the Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Melinda Hollingshead
- Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Diana C. Haines
- Pathology/Histotechnology Laboratory, SAIC Frederick, Inc./Frederick National Laboratory for Cancer Research, National Cancer Institute, Frederick, MD 21702
| | - Donna Butcher
- Pathology/Histotechnology Laboratory, SAIC Frederick, Inc./Frederick National Laboratory for Cancer Research, National Cancer Institute, Frederick, MD 21702
| | - Krishnendu Roy
- Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - James H. Doroshow
- Laboratory of Molecular Pharmacology of the Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
- Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
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55
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Espey MG. Role of oxygen gradients in shaping redox relationships between the human intestine and its microbiota. Free Radic Biol Med 2013; 55:130-40. [PMID: 23127782 DOI: 10.1016/j.freeradbiomed.2012.10.554] [Citation(s) in RCA: 256] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 10/19/2012] [Accepted: 10/24/2012] [Indexed: 01/01/2023]
Abstract
The unique anatomy and physiology of the intestine in conjunction with its microbial content create the steepest oxygen gradients in the body, which plunge to near anoxia at the luminal midpoint. Far from static, intestinal oxygen gradients ebb and flow with every meal. This in turn governs the redox effectors nitric oxide, hydrogen sulfide, and reactive oxygen species of both host and bacterial origin. This review illustrates how the intestine and microbes utilize oxygen gradients as a backdrop for mechanistically shaping redox relationships and a functional coexistence.
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Affiliation(s)
- Michael Graham Espey
- Office of the Scientific Director, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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56
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Menden H, Tate E, Hogg N, Sampath V. LPS-mediated endothelial activation in pulmonary endothelial cells: role of Nox2-dependent IKK-β phosphorylation. Am J Physiol Lung Cell Mol Physiol 2013; 304:L445-55. [PMID: 23333803 DOI: 10.1152/ajplung.00261.2012] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Lipopolysaccharide (LPS)-mediated endothelial activation contributes to lung inflammation and alveolar remodeling seen in premature infants with bronchopulmonary dysplasia (BPD). The mechanisms underlying LPS-mediated oxidative stress and proinflammatory signaling in human pulmonary microvascular endothelial cells (HPMEC) remain unclear. We hypothesized that NADPH oxidase (Nox) mediates LPS-induced endothelial activation in HPMEC by regulating phosphorylation of Toll-like receptor (TLR) pathway proteins. LPS-induced expression of intercellular adhesion molecule 1 (ICAM-1) was associated with increased 2-OH-E(+) (marker for superoxide formation) levels and was attenuated by apocynin and the Nox inhibitor, VAS2870. LPS triggered membrane translocation of p67phox, suggesting activation of Nox2. Silencing Nox2, but not Nox4, suppressed LPS-induced ICAM-1 expression in HPMEC. Immunoprecipitation studies showed that inhibitor of κ-B kinase-β (IKK-β) serine phosphorylation induced by LPS was inhibited by Nox2 silencing. We examined whether Nox2-dependent, LPS-mediated IKK-β phosphorylation was regulated by protein phosphatase 2A (PP2A) or TGF-β associated kinase-1 (TAK1) in HPMEC. LPS increased PP2A activity in HPMEC, and inhibition of PP2A did not alter LPS-mediated ICAM-1 expression but attenuated IKK-β phosphorylation. TAK1 inhibition decreased LPS-induced ICAM-1 expression in HPMEC, and Nox2 silencing attenuated LPS-mediated TAK1 phosphorylation (Thr184/187). We demonstrate that Nox2 regulates LPS-mediated endothelial activation in pulmonary endothelial cells by modulating phosphorylation of key kinases in the TLR signaling cascade. Our data support a novel mechanism by which Nox-dependent signaling regulates proinflammatory signaling in pulmonary endothelial cells. Inhibition of vascular Nox may potentially limit lung injury and alveolar remodeling caused by infections in BPD.
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Affiliation(s)
- Heather Menden
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, USA
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Matsuno K, Iwata K, Matsumoto M, Katsuyama M, Cui W, Murata A, Nakamura H, Ibi M, Ikami K, Zhang J, Matoba S, Jin D, Takai S, Matsubara H, Matsuda N, Yabe-Nishimura C. NOX1/NADPH oxidase is involved in endotoxin-induced cardiomyocyte apoptosis. Free Radic Biol Med 2012; 53:1718-28. [PMID: 22982050 DOI: 10.1016/j.freeradbiomed.2012.08.590] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 08/16/2012] [Accepted: 08/28/2012] [Indexed: 12/29/2022]
Abstract
The functional significance of NOX1/NADPH oxidase in the heart has not been explored due to its low expression relative to other NOX homologs identified so far. We aimed to clarify the role of NOX1/NADPH oxidase in the septic heart by utilizing mice deficient in the Nox1 gene (Nox1(-/Y)). Sepsis was induced by intraperitoneal administration of lipopolysaccharides (LPS: 25mg/kg) or cecal ligation and puncture (CLP) surgery. A marked elevation of NOX1 mRNA was demonstrated in cardiac tissue, which was accompanied by increased production of reactive oxygen species (ROS). In Nox1(-/Y) treated with LPS, cardiac dysfunction and survival were significantly improved compared with wild-type mice (Nox1(+/Y)) treated with LPS. Concomitantly, LPS-induced cardiomyocyte apoptosis and activation of caspase-3 were alleviated in Nox1(-/Y). The level of phosphorylated Akt in cardiac tissue was significantly lowered in Nox1(+/Y) but not in Nox1(-/Y) treated with LPS or that underwent CLP surgery. Increased oxidation of cysteine residues of Akt and enhanced interaction of Akt with protein phosphatase 2A (PP2A), a major phosphatase implicated in the dephosphorylation of Akt, were demonstrated in LPS-treated Nox1(+/Y). These responses to LPS were significantly attenuated in Nox1(-/Y). Taken together, ROS derived from NOX1/NADPH oxidase play a pivotal role in endotoxin-induced cardiomyocyte apoptosis by increasing oxidation of Akt and subsequent dephosphorylation by PP2A. Marked up-regulation of NOX1 may affect the risk of mortality under systemic inflammatory conditions.
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Affiliation(s)
- Kuniharu Matsuno
- Department of Pharmacology, Kyoto Prefectural University of Medicine, Kyoto, Japan
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58
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He H, Genovese KJ, Swaggerty CL, Nisbet DJ, Kogut MH. A comparative study on invasion, survival, modulation of oxidative burst, and nitric oxide responses of macrophages (HD11), and systemic infection in chickens by prevalent poultry Salmonella serovars. Foodborne Pathog Dis 2012; 9:1104-10. [PMID: 23067396 DOI: 10.1089/fpd.2012.1233] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Poultry is a major reservoir for foodborne Salmonella serovars. Salmonella Typhimurium, Salmonella Enteritidis, Salmonella Heidelberg, Salmonella Kentucky, and Salmonella Senftenberg are the most prevalent serovars in U.S. poultry. Information concerning the interactions between different Salmonella species and host cells in poultry is lacking. In the present study, the above mentioned Salmonella serovars were examined for invasion, intracellular survival, and their ability to modulate oxidative burst and nitric oxide (NO) responses in chicken macrophage HD11 cells. All Salmonella serovars demonstrated similar capacity to invade HD11 cells. At 24 h post-infection, a 36-43% reduction of intracellular bacteria, in log(10)(CFU), was observed for Salmonella Typhimurium, Salmonella Heidelberg, Salmonella Kentucky, and Salmonella Senftenberg, whereas a significantly lower reduction (16%) was observed for Salmonella Enteritidis, indicating its higher resistance to the killing by HD11 cells. Production of NO was completely diminished in HD11 cells infected with Salmonella Typhimurium and Salmonella Enteritidis, but remained intact when infected with Salmonella Heidelberg, Salmonella Kentucky, and Salmonella Senftenberg. Phorbol myristate acetate-stimulated oxidative burst in HD11 cells was greatly impaired after infection by each of the five serovars. When newly hatched chickens were challenged orally, a high rate (86-98%) of systemic infection (Salmonella positive in liver/spleen) was observed in birds challenged with Salmonella Typhimurium, Salmonella Enteritidis, Salmonella Heidelberg, and Salmonella Kentucky, while only 14% of the birds were Salmonella Senftenberg positive. However, there was no direct correlation between systemic infection and in vitro differential intracellular survival and modulation of NO response among the tested serovars.
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Affiliation(s)
- Haiqi He
- Southern Plains Agricultural Research Center, Agricultural Research Service, U.S. Department of Agriculture, College Station, Texas 77845, USA.
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59
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Jones RM, Mercante JW, Neish AS. Reactive oxygen production induced by the gut microbiota: pharmacotherapeutic implications. Curr Med Chem 2012; 19:1519-29. [PMID: 22360484 DOI: 10.2174/092986712799828283] [Citation(s) in RCA: 158] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Revised: 12/22/2011] [Accepted: 12/26/2011] [Indexed: 12/18/2022]
Abstract
The resident prokaryotic microbiota of the mammalian intestine influences diverse homeostatic functions, including regulation of cellular growth, maintenance of barrier function, and modulation of immune responses. However, it is unknown how commensal prokaryotic organisms mechanistically influence eukaryotic signaling networks. Recent data has demonstrated that gut epithelia contacted by enteric commensal bacteria rapidly generate reactive oxygen species (ROS). While the induced generation of ROS via stimulation of formyl peptide receptors is a cardinal feature of the cellular response of phagocytes to pathogenic or commensal bacteria, evidence is accumulating that ROS are also similarly elicited in other cell types, including intestinal epithelia, in response to microbial signals. Additionally, ROS have been shown to serve as critical second messengers in multiple signal transduction pathways stimulated by proinflammatory cytokines and growth factors. This physiologically-generated ROS is known to participate in cellular signaling via the rapid and transient oxidative inactivation of a defined class of sensor proteins bearing oxidant-sensitive thiol groups. These proteins include tyrosine phosphatases that serve as regulators of MAP kinase pathways, cytoskeletal dynamics, as well as components involved in control of ubiquitination-mediated NF-κB activation. Consistently, microbial-elicited ROS has been shown to mediate increased cellular proliferation and motility and to modulate innate immune signaling. These results demonstrate how enteric microbiota influence regulatory networks of the mammalian intestinal epithelia. We hypothesize that many of the known effects of the normal microbiota on intestinal physiology, and potential beneficial effects of candidate probiotic bacteria, may be at least partially mediated by this ROS-dependent mechanism.
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Affiliation(s)
- R M Jones
- Emory University School of Medicine, Atlanta, GA 30322, USA
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60
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Reactive oxygen species and nitric oxide in cutaneous leishmaniasis. J Parasitol Res 2012; 2012:203818. [PMID: 22570765 PMCID: PMC3337613 DOI: 10.1155/2012/203818] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Revised: 11/18/2011] [Accepted: 11/22/2011] [Indexed: 01/03/2023] Open
Abstract
Cutaneous leishmaniasis affects millions of people around the world. Several species of Leishmania infect mouse strains, and murine models closely reproduce the cutaneous lesions caused by the parasite in humans. Mouse models have enabled studies on the pathogenesis and effector mechanisms of host resistance to infection. Here, we review the role of nitric oxide (NO), reactive oxygen species (ROS), and peroxynitrite (ONOO−) in the control of parasites by macrophages, which are both the host cells and the effector cells. We also discuss the role of neutrophil-derived oxygen and nitrogen reactive species during infection with Leishmania. We emphasize the role of these cells in the outcome of leishmaniasis early after infection, before the adaptive Th-cell immune response.
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61
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Choi J. Oxidative stress, endogenous antioxidants, alcohol, and hepatitis C: pathogenic interactions and therapeutic considerations. Free Radic Biol Med 2012; 52:1135-50. [PMID: 22306508 DOI: 10.1016/j.freeradbiomed.2012.01.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 01/04/2012] [Accepted: 01/12/2012] [Indexed: 12/16/2022]
Abstract
Hepatitis C virus (HCV) is a blood-borne pathogen that was identified as an etiologic agent of non-A, non-B hepatitis in 1989. HCV is estimated to have infected at least 170 million people worldwide. The majority of patients infected with HCV do not clear the virus and become chronically infected, and chronic HCV infection increases the risk for hepatic steatosis, cirrhosis, and hepatocellular carcinoma. HCV induces oxidative/nitrosative stress from multiple sources, including inducible nitric oxide synthase, the mitochondrial electron transport chain, hepatocyte NAD(P)H oxidases, and inflammation, while decreasing glutathione. The cumulative oxidative burden is likely to promote both hepatic and extrahepatic conditions precipitated by HCV through a combination of local and more distal effects of reactive species, and clinical, animal, and in vitro studies strongly point to a role of oxidative/nitrosative stress in HCV-induced pathogenesis. Oxidative stress and hepatopathogenesis induced by HCV are exacerbated by even low doses of alcohol. Alcohol and reactive species may have other effects on hepatitis C patients such as modulation of the host immune system, viral replication, and positive selection of HCV sequence variants that contribute to antiviral resistance. This review summarizes the current understanding of redox interactions of HCV, outlining key experimental findings, directions for future research, and potential applications to therapy.
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Affiliation(s)
- Jinah Choi
- Department of Molecular Cell Biology, School of Natural Sciences, University of California at Merced, Merced, CA 95343, USA.
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62
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Joo JH, Ryu JH, Kim CH, Kim HJ, Suh MS, Kim JO, Chung SY, Lee SN, Kim HM, Bae YS, Yoon JH. Dual oxidase 2 is essential for the toll-like receptor 5-mediated inflammatory response in airway mucosa. Antioxid Redox Signal 2012; 16:57-70. [PMID: 21714724 DOI: 10.1089/ars.2011.3898] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
AIMS Airway mucosa is constantly exposed to various airborne microbes, and epithelial host defense requires a robust innate immunity. Recently, it has been suggested that NADPH oxidase (NOX) isozymes serve functional roles in toll-like receptor (TLR)-mediated innate immune responses. However, the molecular mechanism between TLR and NOX-mediated reactive oxygen species (ROS) production in human airway mucosa has been poorly understood. RESULTS Here, we show that flagellin-induced ROS generation is dependent on dual oxidase 2 (DUOX2) activation, which is regulated by [Ca(2+)](i) mobilization in primary normal human nasal epithelial (NHNE) cells. Interestingly, we observed that silencing of DUOX2 expression in NHNE cells and nasal epithelium of Duox2 knockout mice failed to trigger mucin and MIP-2? production upon challenging flagellin. INNOVATION Our observation in this study reveals that flagellin-induced hydrogen peroxide (H(2)O(2)) generation is critical for TLR5-dependent innate immune responses, including IL-8 production and MUC5AC expression in the nasal epithelium. Furthermore, DUOX2-mediated H(2)O(2) generation activated by the flagellin-TLR5 axis might serve as a novel therapeutic target for infectious inflammation diseases in the airway tract. CONCLUSION Taken together, we propose that DUOX2 plays pivotal roles in TLR5-dependent inflammatory response of nasal airway epithelium.
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Affiliation(s)
- Jung-Hee Joo
- Research Center for Natural Human Defense System, Yonsei University College of Medicine, Seoul, South Korea
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63
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Abstract
NF-κB is well characterized as a primary mediator of inflammatory responses during infection and immune reactions, but it has recently become evident that NF-κB also mediates a potent cytoprotective, homeostatic function under basal conditions. This role is especially evident in the mammalian intestine, which is challenged not only with a range of microbial pathogens, but is also in constant contact with potent proinflammatory commensal bacteria and their products. Present data lead to the overall conclusion that antiapoptotic actions of NF-κB in intestinal epithelial cells dominate tissue responses to many acute inflammatory and injurious challenges, whereas proinflammatory and cell survival functions of NF-κB in macrophages and T cells govern chronic intestinal inflammation. This review focuses on the protective and homeostatic functions of NF-κB, and the importance of NF-κB in determining host-microbe interactions in the intestinal tract.
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Affiliation(s)
- Lars Eckmann
- Department of Medicine, University of California, 9500 Gilman Drive, La Jolla, San Diego, CA 92093-0063, USA.
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64
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Thorsteinsdottir S, Gudjonsson T, Nielsen OH, Vainer B, Seidelin JB. Pathogenesis and biomarkers of carcinogenesis in ulcerative colitis. Nat Rev Gastroenterol Hepatol 2011; 8:395-404. [PMID: 21647200 DOI: 10.1038/nrgastro.2011.96] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
One of the most serious complications of ulcerative colitis is the development of colorectal cancer. Screening patients with ulcerative colitis by standard histological examination of random intestinal biopsy samples might be inefficient as a method of cancer surveillance. This Review focuses on the current understanding of the pathogenesis of ulcerative colitis-associated colorectal cancer and how this knowledge can be transferred into patient management to assist clinicians and pathologists in identifying patients with ulcerative colitis who have an increased risk of colorectal cancer. Inflammation-driven mechanisms of DNA damage, including the generation and effects of reactive oxygen species, microsatellite instability, telomere shortening and chromosomal instability, are reviewed, as are the molecular responses to genomic stress. We also discuss how these mechanisms can be translated into usable biomarkers. Although progress has been made in the understanding of inflammation-driven carcinogenesis, markers based on these findings possess insufficient sensitivity or specificity to be usable as reliable biomarkers for risk of colorectal cancer development in patients with ulcerative colitis. However, screening for mutations in p53 could be relevant in the surveillance of patients with ulcerative colitis. Several other new biomarkers, including senescence markers and α-methylacyl-CoA-racemase, might be future candidates for preneoplastic markers in ulcerative colitis.
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Affiliation(s)
- Sigrun Thorsteinsdottir
- Department of Gastroenterology, Medical Section, Herlev Hospital, University of Copenhagen, 75 Herlev Ringvej, DK-2730 Herlev, Denmark
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65
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Park GY, Christman JW. Is the cellular response to cigarette smoke predictive of the phenotypic variation of COPD? Am J Physiol Lung Cell Mol Physiol 2011; 300:L809-10. [PMID: 21498627 DOI: 10.1152/ajplung.00108.2011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The adverse health consequences of cigarette smoking are not limited to the lung but also include effects on multiple other organ systems that are exposed directly or indirectly to the hazardous gaseous and soluble compounds generated by burning tobacco. Cigarette smoking (CS) is a risk factor for many major diseases including chronic obstructive pulmonary disease (COPD), atherosclerosis, cerebral and coronary vascular diseases, hypertension, and many types of cancer. Within the diagnosis category of COPD, it is widely recognized that there is substantial phenotypic heterogeneity with respect to both pulmonary and extrapulmonary manifestations. To understand the variability in responses to CS, it becomes essential to decipher the involved mechanisms at a cellular and molecular level that contribute to cigarette-related pathology. In this issue of the Journal, there are three papers (1, 4, 6) that provide insight regarding the molecular pathogenesis of CS-related COPD that could be related to phenotypic variation, by examining three classes of cell types of lung: endothelial cells, epithelial cells, and immune effector cells.
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Affiliation(s)
- Gye Young Park
- Section of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of Illinois, Chicago, 60612, USA.
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66
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Host fibrinogen stably bound to hemozoin rapidly activates monocytes via TLR-4 and CD11b/CD18-integrin: a new paradigm of hemozoin action. Blood 2011; 117:5674-82. [PMID: 21460246 DOI: 10.1182/blood-2010-10-312413] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Natural hemozoin (nHZ), prepared after schizogony, consists of crystalline ferriprotoporphyrin-IX dimers from undigested heme bound to host and parasite proteins and lipids. Phagocytosed nHZ alters important functions of host phagocytes. Most alterations are long-term effects. We show that host fibrinogen (FG) was constantly present (at ~ 1 FG per 25 000 HZ-heme molecules) and stably bound to nHZ from plasma-cultured parasites. FG was responsible for the rapid 100-fold stimulation of reactive oxygen species production and 50-fold increase of TNF and monocyte chemotactic protein 1 by human monocytes. Those effects, starting within minutes after nHZ cell contact, were because of interaction of FG with FG-receptors TLR4 and integrin CD11b/CD18. Receptor blockage by specific mAbs or removal of FG from nHZ abrogated the effects. nHZ-opsonizing IgGs contribute to the stimulatory response but are not essential for FG effects. Immediate increase in reactive oxygen species and TNF may switch on previously described long-term effects of nHZ, largely because of HZ-generated lipo-peroxidation products 15(S,R)-hydroxy-6,8,11,13-eicosatetraenoic acid and 4-hydroxynonenal. The FG/HZ effects mediated by TLR4/integrins represent a novel paradigm of nHZ activity and allow expansion of nHZ effects to nonphagocytic cells, such as endothelia and airway epithelia, and lead to a better understanding of organ pathology in malaria.
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67
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Potentiation of epithelial innate host responses by intercellular communication. PLoS Pathog 2010; 6:e1001194. [PMID: 21124989 PMCID: PMC2987820 DOI: 10.1371/journal.ppat.1001194] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Accepted: 10/13/2010] [Indexed: 12/21/2022] Open
Abstract
The epithelium efficiently attracts immune cells upon infection despite the low number of pathogenic microbes and moderate levels of secreted chemokines per cell. Here we examined whether horizontal intercellular communication between cells may contribute to a coordinated response of the epithelium. Listeria monocytogenes infection, transfection, and microinjection of individual cells within a polarized intestinal epithelial cell layer were performed and activation was determined at the single cell level by fluorescence microscopy and flow cytometry. Surprisingly, chemokine production after L. monocytogenes infection was primarily observed in non-infected epithelial cells despite invasion-dependent cell activation. Whereas horizontal communication was independent of gap junction formation, cytokine secretion, ion fluxes, or nitric oxide synthesis, NADPH oxidase (Nox) 4-dependent oxygen radical formation was required and sufficient to induce indirect epithelial cell activation. This is the first report to describe epithelial cell-cell communication in response to innate immune activation. Epithelial communication facilitates a coordinated infectious host defence at the very early stage of microbial infection. All body surfaces are covered by a single layer of epithelial cells. Epithelial cells form a physical barrier to separate the underlying sterile tissue from the environment. In addition, epithelial cells actively sense bacterial and viral infection. The recognition of pathogenic microorganisms results in cell stimulation and the secretion of soluble mediators that attract professional immune cells to the site of infection. This first line host defence works very efficiently despite the often low number of pathogens and the limited amount of mediators secreted per epithelial cell. We therefore investigated whether infection of one individual epithelial cell would result in activation of other, non-infected cells within a confluent epithelial monolayer resulting in a more substantial host response. Indeed, using the model of the gut pathogen Listeria monocytogenes and monitoring infection and epithelial activation at a single cell level, we can clearly show that the epithelial response is mainly mediated by non-infected cells. Also, we identify oxygen radicals as potential mediators to facilitate horizontal epithelial communication upon immune stimulation. Our results thus provide a novel concept of a coordinated epithelial host response upon microbial infection facilitated by horizontal epithelial communication.
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68
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Ufer C, Wang CC, Borchert A, Heydeck D, Kuhn H. Redox control in mammalian embryo development. Antioxid Redox Signal 2010; 13:833-75. [PMID: 20367257 DOI: 10.1089/ars.2009.3044] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The development of an embryo constitutes a complex choreography of regulatory events that underlies precise temporal and spatial control. Throughout this process the embryo encounters ever changing environments, which challenge its metabolism. Oxygen is required for embryogenesis but it also poses a potential hazard via formation of reactive oxygen and reactive nitrogen species (ROS/RNS). These metabolites are capable of modifying macromolecules (lipids, proteins, nucleic acids) and altering their biological functions. On one hand, such modifications may have deleterious consequences and must be counteracted by antioxidant defense systems. On the other hand, ROS/RNS function as essential signal transducers regulating the cellular phenotype. In this context the combined maternal/embryonic redox homeostasis is of major importance and dysregulations in the equilibrium of pro- and antioxidative processes retard embryo development, leading to organ malformation and embryo lethality. Silencing the in vivo expression of pro- and antioxidative enzymes provided deeper insights into the role of the embryonic redox equilibrium. Moreover, novel mechanisms linking the cellular redox homeostasis to gene expression regulation have recently been discovered (oxygen sensing DNA demethylases and protein phosphatases, redox-sensitive microRNAs and transcription factors, moonlighting enzymes of the cellular redox homeostasis) and their contribution to embryo development is critically reviewed.
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Affiliation(s)
- Christoph Ufer
- Institute of Biochemistry, University Medicine Berlin-Charité, Berlin, FR Germany
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69
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Guiñazú N, Carrera-Silva EA, Becerra MC, Pellegrini A, Albesa I, Gea S. Induction of NADPH oxidase activity and reactive oxygen species production by a single Trypanosoma cruzi antigen. Int J Parasitol 2010; 40:1531-8. [PMID: 20637209 DOI: 10.1016/j.ijpara.2010.05.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 05/10/2010] [Accepted: 05/11/2010] [Indexed: 10/19/2022]
Abstract
Trypanosoma cruzi is an intracellular protozoan parasite that predominantly invades mononuclear phagocytes and is able to establish a persistent infection. The production of reactive oxygen species (ROS) by phagocytes is an innate defence mechanism against microorganisms. It has been postulated that ROS such as superoxide anion (O(2)), hydrogen peroxide and peroxynitrite, may play a crucial role in the control of pathogen growth. However, information on parasite molecules able to trigger ROS production is scarce. In this work, we investigated whether cruzipain, an immunogenic glycoprotein from T. cruzi, was able to trigger the oxidative burst by murine cells. By employing chemiluminiscense and flow-cytometric analysis, we demonstrated that cruzipain induced ROS production in splenocytes from non-immune and cruzipain immune C57BL/6 mice and in a Raw 264.7 macrophage cell line. We also identified an O(2)(-) molecule as one of the ROS produced after antigen stimulation. Cruzipain stimulation induced NOX2 (gp91(phox)) and p47(phox) expression, as well as the co-localisation of both NADPH oxidase enzyme subunits. In the current study, we provide evidence that cruzipain not only increased ROS production but also promoted IL-6 and IL-1β cytokine production. Taken together, we believe these results demonstrate for the first time that cruzipain, a single parasite molecule, in the absence of infection, favors oxidative burst in murine cells. This represents an important advance in the knowledge of parasite molecules that interact with the phagocyte defence mechanism.
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Affiliation(s)
- Natalia Guiñazú
- CIBICI-CONICET, Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.
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70
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Soucy-Faulkner A, Mukawera E, Fink K, Martel A, Jouan L, Nzengue Y, Lamarre D, Vande Velde C, Grandvaux N. Requirement of NOX2 and reactive oxygen species for efficient RIG-I-mediated antiviral response through regulation of MAVS expression. PLoS Pathog 2010; 6:e1000930. [PMID: 20532218 PMCID: PMC2880583 DOI: 10.1371/journal.ppat.1000930] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Accepted: 04/28/2010] [Indexed: 12/22/2022] Open
Abstract
The innate immune response is essential to the host defense against viruses, through restriction of virus replication and coordination of the adaptive immune response. Induction of antiviral genes is a tightly regulated process initiated mainly through sensing of invading virus nucleic acids in the cytoplasm by RIG-I like helicases, RIG-I or Mda5, which transmit the signal through a common mitochondria-associated adaptor, MAVS. Although major breakthroughs have recently been made, much remains unknown about the mechanisms that translate virus recognition into antiviral genes expression. Beside the reputed detrimental role, reactive oxygen species (ROS) act as modulators of cellular signaling and gene regulation. NADPH oxidase (NOX) enzymes are a main source of deliberate cellular ROS production. Here, we found that NOX2 and ROS are required for the host cell to trigger an efficient RIG-I-mediated IRF-3 activation and downstream antiviral IFNbeta and IFIT1 gene expression. Additionally, we provide evidence that NOX2 is critical for the expression of the central mitochondria-associated adaptor MAVS. Taken together these data reveal a new facet to the regulation of the innate host defense against viruses through the identification of an unrecognized role of NOX2 and ROS.
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Affiliation(s)
- Anton Soucy-Faulkner
- CRCHUM - Centre Hospitalier de l'Université de Montréal, Montréal, Québec, Canada
- Department of Biochemistry, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada
| | - Espérance Mukawera
- CRCHUM - Centre Hospitalier de l'Université de Montréal, Montréal, Québec, Canada
| | - Karin Fink
- CRCHUM - Centre Hospitalier de l'Université de Montréal, Montréal, Québec, Canada
- Department of Biochemistry, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada
| | - Alexis Martel
- CRCHUM - Centre Hospitalier de l'Université de Montréal, Montréal, Québec, Canada
- Department of Biochemistry, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada
| | - Loubna Jouan
- CRCHUM - Centre Hospitalier de l'Université de Montréal, Montréal, Québec, Canada
- Department of Medicine, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada
| | - Yves Nzengue
- CRCHUM - Centre Hospitalier de l'Université de Montréal, Montréal, Québec, Canada
- Department of Biochemistry, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada
| | - Daniel Lamarre
- CRCHUM - Centre Hospitalier de l'Université de Montréal, Montréal, Québec, Canada
- Department of Medicine, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada
| | - Christine Vande Velde
- CRCHUM - Centre Hospitalier de l'Université de Montréal, Montréal, Québec, Canada
- Department of Medicine, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada
| | - Nathalie Grandvaux
- CRCHUM - Centre Hospitalier de l'Université de Montréal, Montréal, Québec, Canada
- Department of Biochemistry, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada
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Yvan-Charvet L, Pagler TA, Seimon TA, Thorp E, Welch CL, Witztum JL, Tabas I, Tall AR. ABCA1 and ABCG1 protect against oxidative stress-induced macrophage apoptosis during efferocytosis. Circ Res 2010; 106:1861-9. [PMID: 20431058 DOI: 10.1161/circresaha.110.217281] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Antiatherogenic effects of plasma high-density lipoprotein (HDL) include the ability to inhibit apoptosis of macrophage foam cells. The ATP-binding cassette transporters ABCA1 and ABCG1 have a major role in promoting cholesterol efflux from macrophages to apolipoprotein A-1 and HDL and are upregulated during the phagocytosis of apoptotic cells (efferocytosis). OBJECTIVE The goal of this study was to determine the roles of ABCA1 and ABCG1 in preserving the viability of macrophages during efferocytosis. METHODS AND RESULTS We show that despite similar clearance of apoptotic cells, peritoneal macrophages from Abca1(-/-)Abcg1(-/-), Abcg1(-/-), and, to a lesser extent, Abca1(-/-) mice are much more prone to apoptosis during efferocytosis compared to wild-type cells. Similar findings were observed following incubations with oxidized phospholipids, and the ability of HDL to protect against oxidized phospholipid-induced apoptosis was markedly reduced in Abca1(-/-)Abcg1(-/-) and Abcg1(-/-) cells. These effects were independent of any role of ABCA1 and ABCG1 in mediating oxidized phospholipid efflux but were reversed by cyclodextrin-mediated cholesterol efflux. The apoptotic response observed in Abca1(-/-)Abcg1(-/-) macrophages after oxidized phospholipid exposure or engulfment of apoptotic cells was dependent on an excessive oxidative burst secondary to enhanced assembly of NADPH oxidase (NOX)2 complexes, leading to sustained Jnk activation which turned on the apoptotic cell death program. Increased NOX2 assembly required Toll-like receptors 2/4 and MyD88 signaling, which are known to be enhanced in transporter deficient cells in a lipid raft-dependent fashion. CONCLUSIONS We identified a new beneficial role of ABCA1, ABCG1 and HDL in dampening the oxidative burst and preserving viability of macrophages following exposure to oxidized phospholipids and/or apoptotic cells.
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Affiliation(s)
- Laurent Yvan-Charvet
- Division of Molecular Medicine, Department of Medicine, 630 W 168th St, Columbia University, New York, NY 10032, USA.
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72
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Abstract
Inflammasomes are innate immune signaling pathways that sense pathogens and injury to direct the proteolytic maturation of inflammatory cytokines such as IL-1beta and IL-18. Among inflammasomes, the NLRP3/NALP3 inflammasome is the most studied. However, little is known on the molecular mechanisms that mediate its assembly and activation. Recent findings suggest that ROS are produced by NLRP3/NALP3 activators and are essential secondary messengers signaling NLRP3/NALP3 inflammasome activation.
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Affiliation(s)
- Fabio Martinon
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA.
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73
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Affiliation(s)
- Andrew S. Neish
- Department of Pathology, Emory University School of Medicine
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74
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Lee SH, Park DW, Park SC, Park YK, Hong SY, Kim JR, Lee CH, Baek SH. Calcium-independent phospholipase A2beta-Akt signaling is involved in lipopolysaccharide-induced NADPH oxidase 1 expression and foam cell formation. THE JOURNAL OF IMMUNOLOGY 2009; 183:7497-504. [PMID: 19917703 DOI: 10.4049/jimmunol.0900503] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Foam cell formation is the most important process in atherosclerosis, and low density lipoprotein oxidation by reactive oxygen species (ROS) is the key step in the conversion of macrophages to foam cells. This study reveals the control mechanism of the gene for NADPH oxidase 1 (Nox1), which produces ROS in the formation of foam cells by stimulating TLR4. Treatment of macrophages by the TLR4 agonist LPS stimulated ROS production and ROS-mediated macrophage to foam cell conversion. This LPS-induced ROS production and foam cell formation could be abrogated by pretreatment of macrophages with N-acetyl cysteine or apocynin. LPS increased Nox1 promoter activity, and resultant expression of mRNA and protein. Small interfering RNA mediated inhibition of Nox1 expression decreased LPS-induced ROS production and foam cell formation. LPS-mediated Nox1 expression and the responses occurred in a calcium-independent phospholipase A(2) (iPLA(2))-dependent manner. The iPLA(2)beta-specific inhibitor S-BEL or iPLA(2)beta small interfering RNA attenuated LPS-induced Nox1 expression, ROS production, and foam cell formation. In addition, activation of iPLA(2)beta by LPS caused Akt phosphorylation and was followed by increased Nox1 expression. These results suggest that the binding of LPS and TLR4 increases Nox1 expression through the iPLA(2)beta-Akt signaling pathway, and control ROS production and foam cell formation.
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Affiliation(s)
- Sun-Hye Lee
- Aging-associated Vascular Disease Research Center, Department of Biochemistry and Molecular Biology, College of Medicine, Yeungnam University, Daegu, South Korea
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75
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Allaoui A, Botteaux A, Dumont JE, Hoste C, De Deken X. Dual oxidases and hydrogen peroxide in a complex dialogue between host mucosae and bacteria. Trends Mol Med 2009; 15:571-9. [PMID: 19913458 DOI: 10.1016/j.molmed.2009.10.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Revised: 09/28/2009] [Accepted: 10/06/2009] [Indexed: 02/06/2023]
Abstract
Among the host defense mechanisms against bacteria, leukocyte phagocytosis leads to their hydrogen peroxide (H(2)O(2))-mediated destruction. The recent discovery of dual oxidase (DUOX)-dependent H(2)O(2) generation associated with peroxidase and thiocyanate secretion at the apex of mucosal cells has been similarly interpreted as a killing mechanism. However, the rapid degradation of H(2)O(2) would be expected to reduce the efficiency of this system. It has been demonstrated that H(2)O(2) acts as a chemorepellent for bacteria, and such an effect might be sufficient to block cellular infection. Therefore, H(2)O(2) generation might represent one of the mechanisms that allows the coexistence of mucosae with potentially harmful bacteria. Here, we discuss the possible role of DUOXes and H(2)O(2) in interactions between host mucosae and bacteria to maintain mucosal homeostasis.
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Affiliation(s)
- Abdelmounaaïm Allaoui
- Laboratoire de Bactériologie Moléculaire, Université Libre de Bruxelles (ULB), Campus Erasme, Route de Lennik 808, B-1070 Brussels, Belgium
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76
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Babelova A, Moreth K, Tsalastra-Greul W, Zeng-Brouwers J, Eickelberg O, Young MF, Bruckner P, Pfeilschifter J, Schaefer RM, Gröne HJ, Schaefer L. Biglycan, a danger signal that activates the NLRP3 inflammasome via toll-like and P2X receptors. J Biol Chem 2009; 284:24035-48. [PMID: 19605353 DOI: 10.1074/jbc.m109.014266] [Citation(s) in RCA: 348] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The role of endogenous inducers of inflammation is poorly understood. To produce the proinflammatory master cytokine interleukin (IL)-1beta, macrophages need double stimulation with ligands to both Toll-like receptors (TLRs) for IL-1beta gene transcription and nucleotide-binding oligomerization domain-like receptors for activation of the inflammasome. It is particularly intriguing to define how this complex regulation is mediated in the absence of an infectious trigger. Biglycan, a ubiquitous leucine-rich repeat proteoglycan of the extracellular matrix, interacts with TLR2/4 on macrophages. The objective of this study was to define the role of biglycan in the synthesis and activation of IL-1beta. Here we show that in macrophages, soluble biglycan induces the NLRP3/ASC inflammasome, activating caspase-1 and releasing mature IL-1beta without the need for additional costimulatory factors. This is brought about by the interaction of biglycan with TLR2/4 and purinergic P2X(4)/P2X(7) receptors, which induces receptor cooperativity. Furthermore, reactive oxygen species formation is involved in biglycan-mediated activation of the inflammasome. By signaling through TLR2/4, biglycan stimulates the expression of NLRP3 and pro-IL-1beta mRNA. Both in a model of non-infectious inflammatory renal injury (unilateral ureteral obstruction) and in lipopolysaccharide-induced sepsis, biglycan-deficient mice displayed lower levels of active caspase-1 and mature IL-1beta in the kidney, lung, and circulation. Our results provide evidence for direct activation of the NLRP3 inflammasome by biglycan and describe a fundamental paradigm of how tissue stress or injury is monitored by innate immune receptors detecting the release of the extracellular matrix components and turning such a signal into a robust inflammatory response.
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Affiliation(s)
- Andrea Babelova
- Pharmazentrum Frankfurt/ZAFES, Institut für Allgemeine Pharmakologie und Toxikologie, Klinikum der Goethe-Universität Frankfurt am Main, 60590 Frankfurt am Main, Germany
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77
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Neish AS. Microbes in gastrointestinal health and disease. Gastroenterology 2009; 136:65-80. [PMID: 19026645 PMCID: PMC2892787 DOI: 10.1053/j.gastro.2008.10.080] [Citation(s) in RCA: 874] [Impact Index Per Article: 58.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Revised: 10/29/2008] [Accepted: 10/30/2008] [Indexed: 02/06/2023]
Abstract
Most, if not all, animals coexist with a complement of prokaryotic symbionts that confer a variety of physiologic benefits. In humans, the interaction between animal and bacterial cells is especially important in the gastrointestinal tract. Technical and conceptual advances have enabled rapid progress in characterizing the taxonomic composition, metabolic capacity, and immunomodulatory activity of the human gut microbiota, allowing us to establish its role in human health and disease. The human host coevolved with a normal microbiota over millennia and developed, deployed, and optimized complex immune mechanisms that monitor and control this microbial ecosystem. These cellular mechanisms have homeostatic roles beyond the traditional concept of defense against potential pathogens, suggesting these pathways contribute directly to the well-being of the gut. During their coevolution, the bacterial microbiota has established multiple mechanisms to influence the eukaryotic host, generally in a beneficial fashion, and maintain their stable niche. The prokaryotic genomes of the human microbiota encode a spectrum of metabolic capabilities beyond that of the host genome, making the microbiota an integral component of human physiology. Gaining a fuller understanding of both partners in the normal gut-microbiota interaction may shed light on how the relationship can go awry and contribute to a spectrum of immune, inflammatory, and metabolic disorders and may reveal mechanisms by which this relationship could be manipulated toward therapeutic ends.
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Affiliation(s)
- Andrew S Neish
- Department of Pathology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
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