Publications by authors named "Sarah R Walmsley"

47 Publications

-------A type I IFN, prothrombotic hyperinflammatory neutrophil signature is distinct for COVID-19 ARDS--.

Wellcome Open Res 2021 20;6:38. Epub 2021 May 20.

Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, EH16 4TJ, UK.

Acute respiratory distress syndrome (ARDS) is a severe critical condition with a high mortality that is currently in focus given that it is associated with mortality caused by coronavirus disease 2019 (COVID-19). Neutrophils play a key role in the lung injury characteristic of non-COVID-19 ARDS and there is also accumulating evidence of neutrophil mediated lung injury in patients who succumb to infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We undertook a functional proteomic and metabolomic survey of circulating neutrophil populations, comparing patients with COVID-19 ARDS and non-COVID-19 ARDS to understand the molecular basis of neutrophil dysregulation. Expansion of the circulating neutrophil compartment and the presence of activated low and normal density mature and immature neutrophil populations occurs in ARDS, irrespective of cause. Release of neutrophil granule proteins, neutrophil activation of the clotting cascade and upregulation of the Mac-1 platelet binding complex with formation of neutrophil platelet aggregates is exaggerated in COVID-19 ARDS. Importantly, activation of components of the neutrophil type I interferon responses is seen in ARDS following infection with SARS-CoV-2, with associated rewiring of neutrophil metabolism, and the upregulation of antigen processing and presentation. Whilst dexamethasone treatment constricts the immature low density neutrophil population, it does not impact upon prothrombotic hyperinflammatory neutrophil signatures. Given the crucial role of neutrophils in ARDS and the evidence of a disordered myeloid response observed in COVID-19 patients, this work maps the molecular basis for neutrophil reprogramming in the distinct clinical entities of COVID-19 and non-COVID-19 ARDS.
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http://dx.doi.org/10.12688/wellcomeopenres.16584.2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8112464.2PMC
May 2021

Macrophage miR-210 induction and metabolic reprogramming in response to pathogen interaction boost life-threatening inflammation.

Sci Adv 2021 May 7;7(19). Epub 2021 May 7.

Laboratory of Tumor Inflammation and Angiogenesis, CCB, VIB, Leuven, Belgium.

Unbalanced immune responses to pathogens can be life-threatening although the underlying regulatory mechanisms remain unknown. Here, we show a hypoxia-inducible factor 1α-dependent microRNA (miR)-210 up-regulation in monocytes and macrophages upon pathogen interaction. MiR-210 knockout in the hematopoietic lineage or in monocytes/macrophages mitigated the symptoms of endotoxemia, bacteremia, sepsis, and parasitosis, limiting the cytokine storm, organ damage/dysfunction, pathogen spreading, and lethality. Similarly, pharmacologic miR-210 inhibition improved the survival of septic mice. Mechanistically, miR-210 induction in activated macrophages supported a switch toward a proinflammatory state by lessening mitochondria respiration in favor of glycolysis, partly achieved by downmodulating the iron-sulfur cluster assembly enzyme ISCU. In humans, augmented miR-210 levels in circulating monocytes correlated with the incidence of sepsis, while serum levels of monocyte/macrophage-derived miR-210 were associated with sepsis mortality. Together, our data identify miR-210 as a fine-tuning regulator of macrophage metabolism and inflammatory responses, suggesting miR-210-based therapeutic and diagnostic strategies.
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http://dx.doi.org/10.1126/sciadv.abf0466DOI Listing
May 2021

Hypoxia drives murine neutrophil protein scavenging to maintain central carbon metabolism.

J Clin Invest 2021 May;131(10)

University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom.

Limiting dysfunctional neutrophilic inflammation while preserving effective immunity requires a better understanding of the processes that dictate neutrophil function in the tissues. Quantitative mass-spectrometry identified how inflammatory murine neutrophils regulated expression of cell surface receptors, signal transduction networks, and metabolic machinery to shape neutrophil phenotypes in response to hypoxia. Through the tracing of labeled amino acids into metabolic enzymes, proinflammatory mediators, and granule proteins, we demonstrated that ongoing protein synthesis shapes the neutrophil proteome. To maintain energy supplies in the tissues, neutrophils consumed extracellular proteins to fuel central carbon metabolism. The physiological stresses of hypoxia and hypoglycemia, characteristic of inflamed tissues, promoted this extracellular protein scavenging with activation of the lysosomal compartment, further driving exploitation of the protein-rich inflammatory milieu. This study provides a comprehensive map of neutrophil proteomes, analysis of which has led to the identification of active catabolic and anabolic pathways that enable neutrophils to sustain synthetic and effector functions in the tissues.
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http://dx.doi.org/10.1172/JCI134073DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8121528PMC
May 2021

Neutrophils Fuel Effective Immune Responses through Gluconeogenesis and Glycogenesis.

Cell Metab 2021 02 10;33(2):411-423.e4. Epub 2020 Dec 10.

MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK.

Neutrophils can function and survive in injured and infected tissues, where oxygen and metabolic substrates are limited. Using radioactive flux assays and LC-MS tracing with U-C glucose, glutamine, and pyruvate, we observe that neutrophils require the generation of intracellular glycogen stores by gluconeogenesis and glycogenesis for effective survival and bacterial killing. These metabolic adaptations are dynamic, with net increases in glycogen stores observed following LPS challenge or altitude-induced hypoxia. Neutrophils from patients with chronic obstructive pulmonary disease have reduced glycogen cycling, resulting in impaired function. Metabolic specialization of neutrophils may therefore underpin disease pathology and allow selective therapeutic targeting.
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http://dx.doi.org/10.1016/j.cmet.2020.11.016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7863914PMC
February 2021

Making a bed for viral infections.

Science 2020 10;370(6513):166-167

Centre for Inflammation Research, University of Edinburgh, Edinburgh, UK.

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http://dx.doi.org/10.1126/science.abe3685DOI Listing
October 2020

Semaphorin 3F signaling actively retains neutrophils at sites of inflammation.

J Clin Invest 2020 06;130(6):3221-3237

University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom.

Neutrophilic inflammation is central to disease pathogenesis, for example, in chronic obstructive pulmonary disease, yet the mechanisms that retain neutrophils within tissues remain poorly understood. With emerging evidence that axon guidance factors can regulate myeloid recruitment and that neutrophils can regulate expression of a class 3 semaphorin, SEMA3F, we investigated the role of SEMA3F in inflammatory cell retention within inflamed tissues. We observed that neutrophils upregulate SEMA3F in response to proinflammatory mediators and following neutrophil recruitment to the inflamed lung. In both zebrafish tail injury and murine acute lung injury models of neutrophilic inflammation, overexpression of SEMA3F delayed inflammation resolution with slower neutrophil migratory speeds and retention of neutrophils within the tissues. Conversely, constitutive loss of sema3f accelerated egress of neutrophils from the tail injury site in fish, whereas neutrophil-specific deletion of Sema3f in mice resulted in more rapid neutrophil transit through the airways, and significantly reduced time to resolution of the neutrophilic response. Study of filamentous-actin (F-actin) subsequently showed that SEMA3F-mediated retention is associated with F-actin disassembly. In conclusion, SEMA3F signaling actively regulates neutrophil retention within the injured tissues with consequences for neutrophil clearance and inflammation resolution.
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http://dx.doi.org/10.1172/JCI130834DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7259996PMC
June 2020

Hypoxia Modulates Platelet Purinergic Signalling Pathways.

Thromb Haemost 2020 Feb 13;120(2):253-261. Epub 2019 Dec 13.

APEX (Altitude Physiology Expeditions), Edinburgh, United Kingdom.

Background:  Hypoxia resulting from ascent to high-altitude or pathological states at sea level is known to increase platelet reactivity. Previous work from our group has suggested that this may be adenosine diphosphate (ADP)-specific. Given the clinical importance of drugs targeting ADP pathways, research into the impact of hypoxia on platelet ADP pathways is highly important.

Methods:  Optimul aggregometry was performed on plasma from 29 lowland residents ascending to 4,700 m, allowing systematic assessment of platelet reactivity in response to several platelet agonists. Aggregometry was also performed in response to ADP in the presence of inhibitors of the two main ADP receptors, P2Y and P2Y (MRS2500 and cangrelor, respectively). Phosphorylation of vasodilator-stimulated phosphoprotein (VASP), a key determinant of platelet aggregation, was analysed using the VASPFix assay.

Results:  Hypobaric hypoxia significantly reduced the ability of a fixed concentration of cangrelor to inhibit ADP-induced aggregation and increased basal VASP phosphorylation. However, in the absence of P2Y receptor inhibitors, we did not find evidence of increased platelet sensitivity to any of the agonists tested and found reduced sensitivity to thrombin receptor-activating peptide-6 amide.

Conclusion:  Our results provide evidence of increased P2Y receptor activity at high altitude and suggest down-regulation of the P2Y pathway through increased VASP phosphorylation. These changes in ADP pathway activity are of potential therapeutic significance to high-altitude sojourners and hypoxic sea level patients prescribed platelet inhibitors and warrant further investigation.
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http://dx.doi.org/10.1055/s-0039-3400305DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7286126PMC
February 2020

Pressure regulates immune-cell function.

Authors:
Sarah R Walmsley

Nature 2019 09;573(7772):41-42

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http://dx.doi.org/10.1038/d41586-019-02339-4DOI Listing
September 2019

Hypoxia and the regulation of myeloid cell metabolic imprinting: consequences for the inflammatory response.

EMBO Rep 2019 05 14;20(5). Epub 2019 Mar 14.

Centre for Inflammation Research, The Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK

Inflamed and infected tissue sites are characterised by oxygen and nutrient deprivation. The cellular adaptations to insufficient oxygenation, hypoxia, are mainly regulated by a family of transcription factors known as hypoxia-inducible factors (HIFs). The protein members of the HIF signalling pathway are critical regulators of both the innate and adaptive immune responses, and there is an increasing body of evidence to suggest that the elicited changes occur through cellular metabolic reprogramming. Here, we review the literature on innate immunometabolism to date and discuss the role of hypoxia in innate cell metabolic reprogramming, and how this determines immune responses.
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http://dx.doi.org/10.15252/embr.201847388DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6500960PMC
May 2019

IL4Rα Signaling Abrogates Hypoxic Neutrophil Survival and Limits Acute Lung Injury Responses .

Am J Respir Crit Care Med 2019 07;200(2):235-246

1 Medical Research Council/University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom.

Acute respiratory distress syndrome is defined by the presence of systemic hypoxia and consequent on disordered neutrophilic inflammation. Local mechanisms limiting the duration and magnitude of this neutrophilic response remain poorly understood. To test the hypothesis that during acute lung inflammation tissue production of proresolution type 2 cytokines (IL-4 and IL-13) dampens the proinflammatory effects of hypoxia through suppression of HIF-1α (hypoxia-inducible factor-1α)-mediated neutrophil adaptation, resulting in resolution of lung injury. Neutrophil activation of IL4Ra (IL-4 receptor α) signaling pathways was explored in human acute respiratory distress syndrome patient samples, after the culture of human peripheral blood neutrophils with recombinant IL-4 under conditions of hypoxia, and through the study of IL4Ra-deficient neutrophils in competitive chimera models and wild-type mice treated with IL-4. IL-4 was elevated in human BAL from patients with acute respiratory distress syndrome, and its receptor was identified on patient blood neutrophils. Treatment of human neutrophils with IL-4 suppressed HIF-1α-dependent hypoxic survival and limited proinflammatory transcriptional responses. Increased neutrophil apoptosis in hypoxia, also observed with IL-13, required active STAT signaling, and was dependent on expression of the oxygen-sensing prolyl hydroxylase PHD2. , IL-4Ra-deficient neutrophils had a survival advantage within a hypoxic inflamed niche; in contrast, inflamed lung treatment with IL-4 accelerated resolution through increased neutrophil apoptosis. We describe an important interaction whereby IL4Rα-dependent type 2 cytokine signaling can directly inhibit hypoxic neutrophil survival in tissues and promote resolution of neutrophil-mediated acute lung injury.
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http://dx.doi.org/10.1164/rccm.201808-1599OCDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6635795PMC
July 2019

Inflammation and Hypoxia: HIF and PHD Isoform Selectivity.

Trends Mol Med 2019 01 12;25(1):33-46. Epub 2018 Nov 12.

The University of Edinburgh Centre for Inflammation Research, The Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, UK. Electronic address:

Cells sense and respond to hypoxia through the activity of the transcription factor HIF (hypoxia-inducible factor) and its regulatory hydroxylases, the prolyl hydroxylase domain enzymes (PHDs). Multiple isoforms of HIFs and PHDs exist, and isoform-selective roles have been identified in the context of the inflammatory environment, which is itself frequently hypoxic. Recent advances in the field have highlighted the complexity of this system, particularly with regards to the cell and context-specific activity of HIFs and PHDs. Because novel therapeutic agents which regulate this pathway are nearing the clinic, understanding the role of HIFs and PHDs in inflammation outcomes is an essential step in avoiding off-target effects and, crucially, in developing new anti-inflammatory strategies.
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http://dx.doi.org/10.1016/j.molmed.2018.10.006DOI Listing
January 2019

The role of neutrophils in cancer.

Br Med Bull 2018 12;128(1):5-14

Medical Research Council Centre for Inflammation Research, The Queen's Medical Research Institute, The University of Edinburgh, 47 Little France Crescent, Edinburgh, UK.

Introduction: It has been known for some time that neutrophils are present in the tumour microenvironment, but only recently have their roles been explored.

Sources Of Data: Comprehensive literature search of neutrophils and cancer (PubMed, Google Scholar and CrossRef) for key articles (systematic reviews, meta-analyses, primary research). References from these articles cross-checked for additional relevant studies.

Areas Of Agreement: Neutrophils are a heterogeneous population with both pro- and antitumour roles, and display plasticity. Several neutrophil subpopulations have been identified, defined by a combination of features (density, maturity, surface markers, morphology and anatomical site).

Areas Of Controversy: Limitations in translating murine tumour models to human pathology and paucity of human data. Consensus in defining human neutrophil subpopulations.

Growing Points: Neutrophils as therapeutic targets and as possible playmakers in the biological response to newer targeted cancer drugs.

Areas Timely For Developing Research: Understanding the metabolic programming of neutrophils in the tumour microenvironment.
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http://dx.doi.org/10.1093/bmb/ldy029DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6289220PMC
December 2018

Getting DAMP(s) Wets the Whistle for Neutrophil Recruitment.

Immunity 2018 05;48(5):846-848

University of Edinburgh/MRC Centre for Inflammation Research, The Queens Medical Research Institute, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK. Electronic address:

Neutrophil recruitment in response to pathogen invasion is mediated through "self" tissue damage signals (DAMPs) and pathogen associated signals (PAMPs). In this issue of Immunity, Huang and Niethammer, (2018) demonstrate that DAMP signaling is a prerequisite for neutrophil recruitment.
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http://dx.doi.org/10.1016/j.immuni.2018.04.027DOI Listing
May 2018

Opsonic Phagocytosis in Chronic Obstructive Pulmonary Disease Is Enhanced by Nrf2 Agonists.

Am J Respir Crit Care Med 2018 09;198(6):739-750

5 MRC Centre for Inflammation Research, and.

Rationale: Previous studies have identified defects in bacterial phagocytosis by alveolar macrophages (AMs) in patients with chronic obstructive pulmonary disease (COPD), but the mechanisms and clinical consequences remain incompletely defined.

Objectives: To examine the effect of COPD on AM phagocytic responses and identify the mechanisms, clinical consequences, and potential for therapeutic manipulation of these defects.

Methods: We isolated AMs and monocyte-derived macrophages (MDMs) from a cohort of patients with COPD and control subjects within the Medical Research Council COPDMAP consortium and measured phagocytosis of bacteria in relation to opsonic conditions and clinical features.

Measurements And Main Results: COPD AMs and MDMs have impaired phagocytosis of Streptococcus pneumoniae. COPD AMs have a selective defect in uptake of opsonized bacteria, despite the presence of antipneumococcal antibodies in BAL, not observed in MDMs or healthy donor AMs. AM defects in phagocytosis in COPD are significantly associated with exacerbation frequency, isolation of pathogenic bacteria, and health-related quality-of-life scores. Bacterial binding and initial intracellular killing of opsonized bacteria in COPD AMs was not reduced. COPD AMs have reduced transcriptional responses to opsonized bacteria, such as cellular stress responses that include transcriptional modules involving antioxidant defenses and Nrf2 (nuclear factor erythroid 2-related factor 2)-regulated genes. Agonists of the cytoprotective transcription factor Nrf2 (sulforaphane and compound 7) reverse defects in phagocytosis of S. pneumoniae and nontypeable Haemophilus influenzae by COPD AMs.

Conclusions: Patients with COPD have clinically relevant defects in opsonic phagocytosis by AMs, associated with impaired transcriptional responses to cellular stress, which are reversed by therapeutic targeting with Nrf2 agonists.
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http://dx.doi.org/10.1164/rccm.201705-0903OCDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6222469PMC
September 2018

Pseudomonas expression of an oxygen sensing prolyl hydroxylase homologue regulates neutrophil host responses and .

Wellcome Open Res 2017 26;2:104. Epub 2017 Oct 26.

MRC/University of Edinburgh Centre for Inflammation Research, The Queen's Medical Research Institute, University of Edinburgh, Edinburgh, EH16 4TJ, UK.

Pseudomonas species are adapted to evade innate immune responses and can persist at sites of relative tissue hypoxia, including the mucus-plugged airways of patients with cystic fibrosis and bronchiectasis.  The ability of these bacteria to directly sense and respond to changes in local oxygen availability is in part consequent upon expression of the 2-oxoglutarate oxygenase, prolyl hydroxylase (PPHD), which acts on elongation factor Tu (EF-Tu), and is homologous with the human hypoxia inducible factor (HIF) prolyl hydroxylases. We report that PPHD expression regulates the neutrophil response to acute pseudomonal infection. co-culture experiments were performed with human neutrophils and PPHD-deficient and wild-type bacteria and supernatants, with viable neutrophil counts determined by flow cytometry. consequences of infection with PPHD deficient were determined in an acute pneumonia mouse model following intra-tracheal challenge. Supernatants of PPHD-deficient bacterial cultures contained higher concentrations of the phenazine exotoxin pyocyanin and induced greater acceleration of neutrophil apoptosis than wild-type PAO1 supernatants infection with PPHD mutants compared to wild-type PAO1 controls resulted in increased levels of neutrophil apoptosis and impaired control of infection, with higher numbers of recovered from the lungs of mice infected with the PPHD-deficient strain.  This resulted in an overall increase in mortality in mice infected with the PPHD-deficient strain. Our data show that expression of its prolyl hydroxylase influences the outcome of host-pathogen interactions and , demonstrating the importance of considering how both host and pathogen adaptations to hypoxia together define outcomes of infection. Given that inhibitors for the HIF prolyl hydroxylases are in late stage trials for the treatment of anaemia and that the active sites of PPHD and human HIF prolyl hydroxylases are closely related, the results are of current clinical interest.
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http://dx.doi.org/10.12688/wellcomeopenres.12871.1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5701443PMC
October 2017

Prolyl hydroxylase 2 inactivation enhances glycogen storage and promotes excessive neutrophilic responses.

J Clin Invest 2017 Sep 14;127(9):3407-3420. Epub 2017 Aug 14.

MRC/University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom.

Fully activated innate immune cells are required for effective responses to infection, but their prompt deactivation and removal are essential for limiting tissue damage. Here, we have identified a critical role for the prolyl hydroxylase enzyme Phd2 in maintaining the balance between appropriate, predominantly neutrophil-mediated pathogen clearance and resolution of the innate immune response. We demonstrate that myeloid-specific loss of Phd2 resulted in an exaggerated inflammatory response to Streptococcus pneumonia, with increases in neutrophil motility, functional capacity, and survival. These enhanced neutrophil responses were dependent upon increases in glycolytic flux and glycogen stores. Systemic administration of a HIF-prolyl hydroxylase inhibitor replicated the Phd2-deficient phenotype of delayed inflammation resolution. Together, these data identify Phd2 as the dominant HIF-hydroxylase in neutrophils under normoxic conditions and link intrinsic regulation of glycolysis and glycogen stores to the resolution of neutrophil-mediated inflammatory responses. These results demonstrate the therapeutic potential of targeting metabolic pathways in the treatment of inflammatory disease.
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http://dx.doi.org/10.1172/JCI90848DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5669581PMC
September 2017

Hypoxia and host pathogen responses.

Microbes Infect 2017 03 20;19(3):143. Epub 2017 Jan 20.

Department of Infectious Diseases and Microbiology, University of Lübeck, Lübeck, Germany.

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http://dx.doi.org/10.1016/j.micinf.2017.01.006DOI Listing
March 2017

Exploring the HIFs, buts and maybes of hypoxia signalling in disease: lessons from zebrafish models.

Dis Model Mech 2015 Nov;8(11):1349-60

The Bateson Centre, The University of Sheffield, Sheffield, S10 2TN, UK.

A low level of tissue oxygen (hypoxia) is a physiological feature of a wide range of diseases, from cancer to infection. Cellular hypoxia is sensed by oxygen-sensitive hydroxylase enzymes, which regulate the protein stability of hypoxia-inducible factor α (HIF-α) transcription factors. When stabilised, HIF-α binds with its cofactors to HIF-responsive elements (HREs) in the promoters of target genes to coordinate a wide-ranging transcriptional programme in response to the hypoxic environment. This year marks the 20th anniversary of the discovery of the HIF-1α transcription factor, and in recent years the HIF-mediated hypoxia response is being increasingly recognised as an important process in determining the outcome of diseases such as cancer, inflammatory disease and bacterial infections. Animal models have shed light on the roles of HIF in disease and have uncovered intricate control mechanisms that involve multiple cell types, observations that might have been missed in simpler in vitro systems. These findings highlight the need for new whole-organism models of disease to elucidate these complex regulatory mechanisms. In this Review, we discuss recent advances in our understanding of hypoxia and HIFs in disease that have emerged from studies of zebrafish disease models. Findings from such models identify HIF as an integral player in the disease processes. They also highlight HIF pathway components and their targets as potential therapeutic targets against conditions that range from cancers to infectious disease.
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http://dx.doi.org/10.1242/dmm.021865DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4631790PMC
November 2015

The regulation of pulmonary inflammation by the hypoxia-inducible factor-hydroxylase oxygen-sensing pathway.

Ann Am Thorac Soc 2014 Dec;11 Suppl 5:S271-6

Academic Unit of Respiratory Medicine, Department of Infection and Immunity, The Medical School, University of Sheffield, Sheffield, United Kingdom.

Although the hypoxia-inducible factor (HIF)-hydroxylase oxygen-sensing pathway has been extensively reviewed in the context of cellular responses to hypoxia and cancer biology, its importance in regulating innate immune biology is less well described. In this review, we focus on the role of the HIF-hydroxylase pathway in regulating myeloid cell responses and its relevance to inflammatory lung disease. The more specific roles of individual HIF/ prolyl hydroxylase pathway members in vivo are discussed in the context of lineage-specific rodent models of inflammation, with final reference made to the therapeutic challenges of targeting the HIF/hydroxylase pathway in immune cells.
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http://dx.doi.org/10.1513/AnnalsATS.201403-108AWDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4298968PMC
December 2014

A local circadian clock calls time on lung inflammation.

Nat Med 2014 Aug;20(8):809-11

Academic Unit of Respiratory Medicine, Department of Infection and Immunity, The Medical School, University of Sheffield, Sheffield, UK.

Inflammatory diseases typically display circadian variation in symptom severity. A new study in mice shows how a pulmonary epithelial cell clock controls neutrophil recruitment to the lungs and provides insight into interactions between local and systemic circadian clocks.
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http://dx.doi.org/10.1038/nm.3649DOI Listing
August 2014

HIF-mediated innate immune responses: cell signaling and therapeutic implications.

Hypoxia (Auckl) 2014 24;2:47-58. Epub 2014 May 24.

Academic Unit of Respiratory Medicine, Department of Infection and Immunity, University of Sheffield, Sheffield, UK.

Leukocytes recruited to infected, damaged, or inflamed tissues during an immune response must adapt to oxygen levels much lower than those in the circulation. Hypoxia inducible factors (HIFs) are key mediators of cellular responses to hypoxia and, as in other cell types, HIFs are critical for the upregulation of glycolysis, which enables innate immune cells to produce adenosine triphosphate anaerobically. An increasing body of evidence demonstrates that hypoxia also regulates many other innate immunological functions, including cell migration, apoptosis, phagocytosis of pathogens, antigen presentation and production of cytokines, chemokines, and angiogenic and antimicrobial factors. Many of these functions are mediated by HIFs, which are not only stabilized posttranslationally by hypoxia, but also transcriptionally upregulated by inflammatory signals. Here, we review the role of HIFs in the responses of innate immune cells to hypoxia, both in vitro and in vivo, with a particular focus on myeloid cells, on which the majority of studies have so far been carried out.
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http://dx.doi.org/10.2147/HP.S50269DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5045056PMC
May 2014

Neutrophil energetics and oxygen sensing.

Blood 2014 May;123(18):2753-4

UNIVERSITY OF SHEFFIELD.

In this issue of Blood, Jun et al, through the study of neutrophils deficient in the glucose-6-phosphate transporter, describe a novel role for the peroxisome proliferator-activated receptor-γ (PPARG) pathway in the regulation of key neutrophil functions and link this to concomitant hypoxia-inducible factor (HIF) 1α stabilization.
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http://dx.doi.org/10.1182/blood-2014-03-560409DOI Listing
May 2014

A zebrafish compound screen reveals modulation of neutrophil reverse migration as an anti-inflammatory mechanism.

Sci Transl Med 2014 Feb;6(225):225ra29

Medical Research Council Centre for Developmental and Biomedical Genetics, University of Sheffield, Sheffield S10 2TN, UK.

Diseases of failed inflammation resolution are common and largely incurable. Therapeutic induction of inflammation resolution is an attractive strategy to bring about healing without increasing susceptibility to infection. However, therapeutic targeting of inflammation resolution has been hampered by a lack of understanding of the underlying molecular controls. To address this drug development challenge, we developed an in vivo screen for proresolution therapeutics in a transgenic zebrafish model. Inflammation induced by sterile tissue injury was assessed for accelerated resolution in the presence of a library of known compounds. Of the molecules with proresolution activity, tanshinone IIA, derived from a Chinese medicinal herb, potently induced inflammation resolution in vivo both by induction of neutrophil apoptosis and by promoting reverse migration of neutrophils. Tanshinone IIA blocked proinflammatory signals in vivo, and its effects are conserved in human neutrophils, supporting a potential role in treating human inflammation and providing compelling evidence of the translational potential of this screening strategy.
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http://dx.doi.org/10.1126/scitranslmed.3007672DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4247228PMC
February 2014

Hypoxia inducible factor signaling modulates susceptibility to mycobacterial infection via a nitric oxide dependent mechanism.

PLoS Pathog 2013 19;9(12):e1003789. Epub 2013 Dec 19.

Institute of Biology, Leiden University, Leiden, The Netherlands.

Tuberculosis is a current major world-health problem, exacerbated by the causative pathogen, Mycobacterium tuberculosis (Mtb), becoming increasingly resistant to conventional antibiotic treatment. Mtb is able to counteract the bactericidal mechanisms of leukocytes to survive intracellularly and develop a niche permissive for proliferation and dissemination. Understanding of the pathogenesis of mycobacterial infections such as tuberculosis (TB) remains limited, especially for early infection and for reactivation of latent infection. Signaling via hypoxia inducible factor α (HIF-α) transcription factors has previously been implicated in leukocyte activation and host defence. We have previously shown that hypoxic signaling via stabilization of Hif-1α prolongs the functionality of leukocytes in the innate immune response to injury. We sought to manipulate Hif-α signaling in a well-established Mycobacterium marinum (Mm) zebrafish model of TB to investigate effects on the host's ability to combat mycobacterial infection. Stabilization of host Hif-1α, both pharmacologically and genetically, at early stages of Mm infection was able to reduce the bacterial burden of infected larvae. Increasing Hif-1α signaling enhanced levels of reactive nitrogen species (RNS) in neutrophils prior to infection and was able to reduce larval mycobacterial burden. Conversely, decreasing Hif-2α signaling enhanced RNS levels and reduced bacterial burden, demonstrating that Hif-1α and Hif-2α have opposing effects on host susceptibility to mycobacterial infection. The antimicrobial effect of Hif-1α stabilization, and Hif-2α reduction, were demonstrated to be dependent on inducible nitric oxide synthase (iNOS) signaling at early stages of infection. Our findings indicate that induction of leukocyte iNOS by stabilizing Hif-1α, or reducing Hif-2α, aids the host during early stages of Mm infection. Stabilization of Hif-1α therefore represents a potential target for therapeutic intervention against tuberculosis.
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http://dx.doi.org/10.1371/journal.ppat.1003789DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3868520PMC
September 2014

Hypoxia-inducible factor 2α regulates key neutrophil functions in humans, mice, and zebrafish.

Blood 2014 Jan 6;123(3):366-76. Epub 2013 Nov 6.

Department of Infection and Immunity and.

Neutrophil lifespan and function are regulated by hypoxia via components of the hypoxia inducible factor (HIF)/von Hippel Lindau/hydroxylase pathway, including specific roles for HIF-1α and prolyl hydroxylase-3. HIF-2α has both distinct and overlapping biological roles with HIF-1α and has not previously been studied in the context of neutrophil biology. We investigated the role of HIF-2α in regulating key neutrophil functions. Human and murine peripheral blood neutrophils expressed HIF-2α, with expression up-regulated by acute and chronic inflammatory stimuli and in disease-associated inflammatory neutrophil. HIF2A gain-of-function mutations resulted in a reduction in neutrophil apoptosis both ex vivo, through the study of patient cells, and in vivo in a zebrafish tail injury model. In contrast, HIF-2α-deficient murine inflammatory neutrophils displayed increased sensitivity to nitrosative stress induced apoptosis ex vivo and increased neutrophil apoptosis in vivo, resulting in a reduction in neutrophilic inflammation and reduced tissue injury. Expression of HIF-2α was temporally dissociated from HIF-1α in vivo and predominated in the resolution phase of inflammation. These data support a critical and selective role for HIF-2α in persistence of neutrophilic inflammation and provide a platform to dissect the therapeutic utility of targeting HIF-2α in chronic inflammatory diseases.
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http://dx.doi.org/10.1182/blood-2013-05-500207DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3894493PMC
January 2014

Cezanne regulates inflammatory responses to hypoxia in endothelial cells by targeting TRAF6 for deubiquitination.

Circ Res 2013 Jun 5;112(12):1583-91. Epub 2013 Apr 5.

Department of Cardiovascular Science, University of Sheffield, Sheffield S10 2RX, UK.

Rationale: Hypoxia followed by reoxygenation promotes inflammation by activating nuclear factor κB transcription factors in endothelial cells (ECs). This process involves modification of the signaling intermediary tumor necrosis factor receptor-associated factor 6 with polyubiquitin chains. Thus, cellular mechanisms that suppress tumor necrosis factor receptor-associated factor 6 ubiquitination are potential therapeutic targets to reduce inflammation in hypoxic tissues.

Objective: In this study, we tested the hypothesis that endothelial activation in response to hypoxia-reoxygenation can be influenced by Cezanne, a deubiquitinating enzyme that cleaves ubiquitin from specific modified proteins.

Methods And Results: Studies of cultured ECs demonstrated that hypoxia (1% oxygen) induced Cezanne via p38 mitogen-activated protein kinase-dependent transcriptional and post-transcriptional mechanisms. Hypoxia-reoxygenation had minimal effects on proinflammatory signaling in unmanipulated ECs but significantly enhanced Lys63 polyubiquitination of tumor necrosis factor receptor-associated factor 6, activation of nuclear factor κB, and expression of inflammatory genes after silencing of Cezanne. Thus, although hypoxia primed cells for inflammatory activation, it simultaneously induced Cezanne, which impeded signaling to nuclear factor κB by suppressing tumor necrosis factor receptor-associated factor 6 ubiquitination. Similarly, ischemia induced Cezanne in the murine kidney in vascular ECs, glomerular ECs, podocytes, and epithelial cells, and genetic deletion of Cezanne enhanced renal inflammation and injury in murine kidneys exposed to ischemia followed by reperfusion.

Conclusions: We conclude that inflammatory responses to ischemia are controlled by a balance between ubiquitination and deubiquitination, and that Cezanne is a key regulator of this process. Our observations have important implications for therapeutic targeting of inflammation and injury during ischemia-reperfusion.
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http://dx.doi.org/10.1161/CIRCRESAHA.111.300119DOI Listing
June 2013

Hypoxia, the HIF pathway and neutrophilic inflammatory responses.

Biol Chem 2013 Apr;394(4):471-7

Department of Infection and Immunity, University of Sheffield, Sheffield, UK.

Many inflammatory diseases are characterised by persistent and inappropriate neutrophil activation, systemic or localised hypoxia, and bacterial colonisation. Hypoxia represents an important regulator of inflammatory responses because it inhibits neutrophil apoptosis, a process central to the timely resolution of inflammation. Progress in understanding how cells respond to hypoxia has led to the identification of hypoxia-inducible transcription factors (HIFs) and their hydroxylation by the prolyl hydroxylase enzymes. There is now a significant body of data to support a critical role for this HIF pathway in regulating neutrophil function. Moreover, manipulations of specific components of this pathway have very divergent effects on myeloid cell function. In this review, we will discuss the role individual members of the HIF pathway play in regulating key neutrophil functions and the implications this has for the development of effective therapeutic strategies that selectively target inappropriate neutrophil persistence while maintaining a fully competent immune response.
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http://dx.doi.org/10.1515/hsz-2012-0335DOI Listing
April 2013

Functional redundancy of class I phosphoinositide 3-kinase (PI3K) isoforms in signaling growth factor-mediated human neutrophil survival.

PLoS One 2012 24;7(9):e45933. Epub 2012 Sep 24.

Department of Medicine, University of Cambridge School of Clinical Medicine, Addenbrooke's and Papworth Hospitals, Cambridge, United Kingdom.

We have investigated the contribution of individual phosphoinositide 3-kinase (PI3K) Class I isoforms to the regulation of neutrophil survival using (i) a panel of commercially available small molecule isoform-selective PI3K Class I inhibitors, (ii) novel inhibitors, which target single or multiple Class I isoforms (PI3Kα, PI3Kβ, PI3Kδ, and PI3Kγ), and (iii) transgenic mice lacking functional PI3K isoforms (p110δ(KO)γ(KO) or p110γ(KO)). Our data suggest that there is considerable functional redundancy amongst Class I PI3Ks (both Class IA and Class IB) with regard to GM-CSF-mediated suppression of neutrophil apoptosis. Hence pharmacological inhibition of any 3 or more PI3K isoforms was required to block the GM-CSF survival response in human neutrophils, with inhibition of individual or any two isoforms having little or no effect. Likewise, isolated blood neutrophils derived from double knockout PI3K p110δ(KO)γ(KO) mice underwent normal time-dependent constitutive apoptosis and displayed identical GM-CSF mediated survival to wild type cells, but were sensitized to pharmacological inhibition of the remaining PI3K isoforms. Surprisingly, the pro-survival neutrophil phenotype observed in patients with an acute exacerbation of chronic obstructive pulmonary disease (COPD) was resilient to inactivation of the PI3K pathway.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0045933PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3454369PMC
March 2013