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Abstract
The cause of Crohn’s disease (CD) has posed a conundrum for at least a century. A large body of work coupled with recent technological advances in genome research have at last started to provide some of the answers. Initially this review seeks to explain and to differentiate between bowel inflammation in the primary immunodeficiencies that generally lead to very early onset diffuse bowel inflammation in humans and in animal models, and the real syndrome of CD. In the latter, a trigger, almost certainly enteric infection by one of a multitude of organisms, allows the faeces access to the tissues, at which stage the response of individuals predisposed to CD is abnormal. Direct investigation of patients’ inflammatory response together with genome-wide association studies (GWAS) and DNA sequencing indicate that in CD the failure of acute inflammation and the clearance of bacteria from the tissues, and from within cells, is defective. The retained faecal products result in the characteristic chronic granulomatous inflammation and adaptive immune response. In this review I will examine the contemporary evidence that has led to this understanding, and look for explanations for the recent dramatic increase in the incidence of this disease.
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Abstract
The cause of Crohn's disease (CD) has posed a conundrum for at least a century. A large body of work coupled with recent technological advances in genome research have at last started to provide some of the answers. Initially this review seeks to explain and to differentiate between bowel inflammation in the primary immunodeficiencies that generally lead to very early onset diffuse bowel inflammation in humans and in animal models, and the real syndrome of CD. In the latter, a trigger, almost certainly enteric infection by one of a multitude of organisms, allows the faeces access to the tissues, at which stage the response of individuals predisposed to CD is abnormal. Direct investigation of patients' inflammatory response together with genome-wide association studies (GWAS) and DNA sequencing indicate that in CD the failure of acute inflammation and the clearance of bacteria from the tissues, and from within cells, is defective. The retained faecal products result in the characteristic chronic granulomatous inflammation and adaptive immune response. In this review I will examine the contemporary evidence that has led to this understanding, and look for explanations for the recent dramatic increase in the incidence of this disease.
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53
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Nault L, Bouchab L, Dupré-Crochet S, Nüße O, Erard M. Environmental Effects on Reactive Oxygen Species Detection-Learning from the Phagosome. Antioxid Redox Signal 2016; 25:564-76. [PMID: 27225344 DOI: 10.1089/ars.2016.6747] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
SIGNIFICANCE Reactive oxygen species (ROS) fulfill numerous roles in biology ranging from signal transduction to the induction of cell death. To advance our understanding of these sometimes contradictory roles, quantitative, specific, and sensitive ROS measurements are required. RECENT ADVANCES Several organic or genetically encoded probes were successfully developed for ROS detection. CRITICAL ISSUES In some cases, ROS production occurs in a harsh environment such as low pH or high concentration of proteases. However, the ROS sensor may be sensitive to such environmental conditions and therefore becomes inaccurate. While the sensitivity of many ROS sensors to pH is known, many other environmental conditions remain unexplored. This article illustrates the interference between ROS sensors and their environment using the phagosome as an example. In the phagosome, pH changes, high concentration of ROS, and the presence of many proteases generate a hostile and rapidly changing environment. FUTURE DIRECTIONS Difficulties due to cell movement and continuous formation of new phagosomes can be reduced by ratio measurements, if appropriate dyes are identified. For detection in live cells and subcellular locations, fluorescent proteins (FPs) offer several advantages and are used to create biosensors for ROS. Some FPs are directly sensitive to certain ROS as shown here. Although this may compromise their use in an environment with high levels of ROS, it can also be exploited for ROS measurement directly with the FPs themselves. For all types of ROS detection, we suggest a set of basic guidelines for testing the environmental sensitivity of an ROS sensor. Antioxid. Redox Signal. 25, 564-576.
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Affiliation(s)
- Laurent Nault
- Laboratoire de Chimie Physique, Université Paris-Sud, CNRS UMR 8000, Université Paris Saclay , Orsay, France
| | - Leïla Bouchab
- Laboratoire de Chimie Physique, Université Paris-Sud, CNRS UMR 8000, Université Paris Saclay , Orsay, France
| | - Sophie Dupré-Crochet
- Laboratoire de Chimie Physique, Université Paris-Sud, CNRS UMR 8000, Université Paris Saclay , Orsay, France
| | - Oliver Nüße
- Laboratoire de Chimie Physique, Université Paris-Sud, CNRS UMR 8000, Université Paris Saclay , Orsay, France
| | - Marie Erard
- Laboratoire de Chimie Physique, Université Paris-Sud, CNRS UMR 8000, Université Paris Saclay , Orsay, France
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Segal AW. NADPH oxidases as electrochemical generators to produce ion fluxes and turgor in fungi, plants and humans. Open Biol 2016; 6:160028. [PMID: 27249799 PMCID: PMC4892433 DOI: 10.1098/rsob.160028] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 04/21/2016] [Indexed: 02/07/2023] Open
Abstract
The NOXs are a family of flavocytochromes whose basic structure has been largely conserved from algae to man. This is a very simple system. NADPH is generally available, in plants it is a direct product of photosynthesis, and oxygen is a largely ubiquitous electron acceptor, and the electron-transporting core of an FAD and two haems is the minimal required to pass electrons across the plasma membrane. These NOXs have been shown to be essential for diverse functions throughout the biological world and, lacking a clear mechanism of action, their effects have generally been attributed to free radical reactions. Investigation into the function of neutrophil leucocytes has demonstrated that electron transport through the prototype NOX2 is accompanied by the generation of a charge across the membrane that provides the driving force propelling protons and other ions across the plasma membrane. The contention is that the primary function of the NOXs is to supply the driving force to transport ions, the nature of which will depend upon the composition and characteristics of the local ion channels, to undertake a host of diverse functions. These include the generation of turgor in fungi and plants for the growth of filaments and invasion by appressoria in the former, and extension of pollen tubes and root hairs, and stomatal closure, in the latter. In neutrophils, they elevate the pH in the phagocytic vacuole coupled to other ion fluxes. In endothelial cells of blood vessels, they could alter luminal volume to regulate blood pressure and tissue perfusion.
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Affiliation(s)
- Anthony W Segal
- Division of Medicine, UCL, 5 University Street, London WC1E 6JJ, UK
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55
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Abstract
Neutrophils are essential for killing bacteria and other microorganisms, and they also have a significant role in regulating the inflammatory response. Stimulated neutrophils activate their NADPH oxidase (NOX2) to generate large amounts of superoxide, which acts as a precursor of hydrogen peroxide and other reactive oxygen species that are generated by their heme enzyme myeloperoxidase. When neutrophils engulf bacteria they enclose them in small vesicles (phagosomes) into which superoxide is released by activated NOX2 on the internalized neutrophil membrane. The superoxide dismutates to hydrogen peroxide, which is used by myeloperoxidase to generate other oxidants, including the highly microbicidal species hypochlorous acid. NOX activation occurs at other sites in the cell, where it is considered to have a regulatory function. Neutrophils also release oxidants, which can modify extracellular targets and affect the function of neighboring cells. We discuss the identity and chemical properties of the specific oxidants produced by neutrophils in different situations, and what is known about oxidative mechanisms of microbial killing, inflammatory tissue damage, and signaling.
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Affiliation(s)
- Christine C Winterbourn
- Centre for Free Radical Research, Department of Pathology, University of Otago, Christchurch 8011, New Zealand; , ,
| | - Anthony J Kettle
- Centre for Free Radical Research, Department of Pathology, University of Otago, Christchurch 8011, New Zealand; , ,
| | - Mark B Hampton
- Centre for Free Radical Research, Department of Pathology, University of Otago, Christchurch 8011, New Zealand; , ,
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56
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Leliefeld PHC, Wessels CM, Leenen LPH, Koenderman L, Pillay J. The role of neutrophils in immune dysfunction during severe inflammation. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2016; 20:73. [PMID: 27005275 PMCID: PMC4804478 DOI: 10.1186/s13054-016-1250-4] [Citation(s) in RCA: 171] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Critically ill post-surgical, post-trauma and/or septic patients are characterised by severe inflammation. This immune response consists of both a pro- and an anti-inflammatory component. The pro-inflammatory component contributes to (multiple) organ failure whereas occurrence of immune paralysis predisposes to infections. Strikingly, infectious complications arise in these patients despite the presence of a clear neutrophilia. We propose that dysfunction of neutrophils potentially increases the susceptibility to infections or can result in the inability to clear existing infections. Under homeostatic conditions these effector cells of the innate immune system circulate in a quiescent state and serve as the first line of defence against invading pathogens. In severe inflammation, however, neutrophils are rapidly activated, which affects their functional capacities, such as chemotaxis, phagocytosis, intra-cellular killing, NETosis, and their capacity to modulate adaptive immunity. This review provides an overview of the current understanding of neutrophil dysfunction in severe inflammation. We will discuss the possible mechanisms of downregulation of anti-microbial function, suppression of adaptive immunity by neutrophils and the contribution of neutrophil subsets to immune paralysis.
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Affiliation(s)
- Pieter H C Leliefeld
- Department of Surgery, University Medical Center Utrecht, Utrecht, The Netherlands. .,Laboratory of Translational Immunology, University Medical Center Utrecht, Utrecht, The Netherlands.
| | - Catharina M Wessels
- Department of Surgery, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Luke P H Leenen
- Department of Surgery, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Leo Koenderman
- Department of Respiratory Medicine, University Medical Center Utrecht, Utrecht, The Netherlands.,Laboratory of Translational Immunology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Janesh Pillay
- Laboratory of Translational Immunology, University Medical Center Utrecht, Utrecht, The Netherlands.,Department of Anesthesiology and Critical Care, University Medical Center Utrecht, Utrecht, The Netherlands
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57
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Ageing-Associated Oxidative Stress and Inflammation Are Alleviated by Products from Grapes. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:6236309. [PMID: 27034739 PMCID: PMC4789514 DOI: 10.1155/2016/6236309] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 02/03/2016] [Accepted: 02/07/2016] [Indexed: 12/13/2022]
Abstract
Advanced age is associated with increased incidence of a variety of chronic disease states which share oxidative stress and inflammation as causative role players. Furthermore, data point to a role for both cumulative oxidative stress and low grade inflammation in the normal ageing process, independently of disease. Therefore, arguably the best route with which to address premature ageing, as well as age-associated diseases such as diabetes, cardiovascular disease, and dementia, is preventative medicine aimed at modulation of these two responses, which are intricately interlinked. In this review, we provide a detailed account of the literature on the communication of these systems in the context of ageing, but with inclusion of relevant data obtained in other models. In doing so, we attempted to more clearly elucidate or identify the most probable cellular or molecular targets for preventative intervention. In addition, given the absence of a clear pharmaceutical solution in this context, together with the ever-increasing consumer bias for natural medicine, we provide an overview of the literature on grape (Vitis vinifera) derived products, for which beneficial effects are consistently reported in the context of both oxidative stress and inflammation.
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58
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Huang J, Milton A, Arnold RD, Huang H, Smith F, Panizzi JR, Panizzi P. Methods for measuring myeloperoxidase activity toward assessing inhibitor efficacy in living systems. J Leukoc Biol 2016; 99:541-8. [PMID: 26884610 DOI: 10.1189/jlb.3ru0615-256r] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 01/11/2016] [Indexed: 12/23/2022] Open
Abstract
Myeloperoxidase aids in clearance of microbes by generation of peroxidase-mediated oxidants that kill leukocyte-engulfed pathogens. In this review, we will examine 1) strategies for in vitro evaluation of myeloperoxidase function and its inhibition, 2) ways to monitor generation of certain oxidant species during inflammation, and 3) how these methods can be used to approximate the total polymorphonuclear neutrophil chemotaxis following insult. Several optical imaging probes are designed to target reactive oxygen and nitrogen species during polymorphonuclear neutrophil inflammatory burst following injury. Here, we review the following 1) the broad effect of myeloperoxidase on normal physiology, 2) the difference between myeloperoxidase and other peroxidases, 3) the current optical probes available for use as surrogates for direct measures of myeloperoxidase-derived oxidants, and 4) the range of preclinical options for imaging myeloperoxidase accumulation at sites of inflammation in mice. We also stress the advantages and drawbacks of each of these methods, the pharmacokinetic considerations that may limit probe use to strictly cell cultures for some reactive oxygen and nitrogen species, rather than in vivo utility as indicators of myeloperoxidase function. Taken together, our review should shed light on the fundamental rational behind these techniques for measuring myeloperoxidase activity and polymorphonuclear neutrophil response after injury toward developing safe myeloperoxidase inhibitors as potential therapy for chronic obstructive pulmonary disease and rheumatoid arthritis.
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Affiliation(s)
- Jiansheng Huang
- *Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, Alabama, USA Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama, USA
| | - Amber Milton
- *Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, Alabama, USA Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama, USA
| | - Robert D Arnold
- *Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, Alabama, USA Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama, USA
| | - Hui Huang
- *Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, Alabama, USA Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama, USA
| | - Forrest Smith
- *Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, Alabama, USA Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama, USA
| | - Jennifer R Panizzi
- *Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, Alabama, USA Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama, USA
| | - Peter Panizzi
- *Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, Alabama, USA Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama, USA
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