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  1. Article ; Online: Neutrophil Extracellular Traps in Fatal COVID-19-Associated Lung Injury

    Astrid Obermayer / Lisa-Maria Jakob / Jasmin D. Haslbauer / Matthias S. Matter / Alexandar Tzankov / Walter Stoiber

    Disease Markers, Vol

    2021  Volume 2021

    Abstract: An excess formation of neutrophil extracellular traps (NETs), previously shown to be strongly associated with cytokine storm and acute respiratory distress syndrome (ARDS) with prevalent endothelial dysfunction and thrombosis, has been postulated to be a ...

    Abstract An excess formation of neutrophil extracellular traps (NETs), previously shown to be strongly associated with cytokine storm and acute respiratory distress syndrome (ARDS) with prevalent endothelial dysfunction and thrombosis, has been postulated to be a central factor influencing the pathophysiology and clinical presentation of severe COVID-19. A growing number of serological and morphological evidence has added to this assumption, also in regard to potential treatment options. In this study, we used immunohistochemistry and histochemistry to trace NETs and their molecular markers in autopsy lung tissue from seven COVID-19 patients. Quantification of key immunomorphological features enabled comparison with non-COVID-19 diffuse alveolar damage. Our results strengthen and extend recent findings, confirming that NETs are abundantly present in seriously damaged COVID-19 lung tissue, especially in association with microthrombi of the alveolar capillaries. In addition, we provide evidence that low-density neutrophils (LDNs), which are especially prone to NETosis, contribute substantially to COVID-19-associated lung damage in general and vascular blockages in particular.
    Keywords Medicine (General) ; R5-920
    Subject code 610
    Language English
    Publishing date 2021-01-01T00:00:00Z
    Publisher Hindawi Limited
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: The Role of Reactive Oxygen Species (ROS) in the Formation of Extracellular Traps (ETs) in Humans

    Walter Stoiber / Astrid Obermayer / Peter Steinbacher / Wolf-Dietrich Krautgartner

    Biomolecules, Vol 5, Iss 2, Pp 702-

    2015  Volume 723

    Abstract: Extracellular traps (ETs) are reticulate structures of extracellular DNA associated with antimicrobial molecules. Their formation by phagocytes (mainly by neutrophils: NETs) has been identified as an essential element of vertebrate innate immune defense. ...

    Abstract Extracellular traps (ETs) are reticulate structures of extracellular DNA associated with antimicrobial molecules. Their formation by phagocytes (mainly by neutrophils: NETs) has been identified as an essential element of vertebrate innate immune defense. However, as ETs are also toxic to host cells and potent triggers of autoimmunity, their role between pathogen defense and human pathogenesis is ambiguous, and they contribute to a variety of acute and chronic inflammatory diseases. Since the discovery of ET formation (ETosis) a decade ago, evidence has accumulated that most reaction cascades leading to ET release involve ROS. An important new facet was added when it became apparent that ETosis might be directly linked to, or be a variant of, the autophagy cell death pathway. The present review analyzes the evidence to date on the interplay between ROS, autophagy and ETosis, and highlights and discusses several further aspects of the ROS-ET relationship that are incompletely understood. These aspects include the role of NADPH oxidase-derived ROS, the molecular requirements of NADPH oxidase-dependent ETosis, the roles of NADPH oxidase subtypes, extracellular ROS and of ROS from sources other than NADPH oxidase, and the present evidence for ROS-independent ETosis. We conclude that ROS interact with ETosis in a multidimensional manner, with influence on whether ETosis shows beneficial or detrimental effects.
    Keywords neutrophils ; NETs ; autophagy ; NADPH oxidase ; MAPK/ERK ; inflammation ; Biology (General) ; QH301-705.5 ; Science ; Q
    Subject code 572
    Language English
    Publishing date 2015-05-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Scalable Enrichment of Immunomodulatory Human Acute Myeloid Leukemia Cell Line-Derived Extracellular Vesicles

    Heide-Marie Binder / Nicole Maeding / Martin Wolf / André Cronemberger Andrade / Balazs Vari / Linda Krisch / Fausto Gueths Gomes / Constantin Blöchl / Katharina Muigg / Rodolphe Poupardin / Anna M. Raninger / Thomas Heuser / Astrid Obermayer / Patricia Ebner-Peking / Lisa Pleyer / Richard Greil / Christian G. Huber / Katharina Schallmoser / Dirk Strunk

    Cells, Vol 10, Iss 3321, p

    2021  Volume 3321

    Abstract: Acute myeloid leukemia (AML) cells can secrete trophic factors, including extracellular vesicles (EVs), instructing the stromal leukemic niche. Here, we introduce a scalable workflow for purification of immunomodulatory AML-EVs to compare their phenotype ...

    Abstract Acute myeloid leukemia (AML) cells can secrete trophic factors, including extracellular vesicles (EVs), instructing the stromal leukemic niche. Here, we introduce a scalable workflow for purification of immunomodulatory AML-EVs to compare their phenotype and function to the parental AML cells and their secreted soluble factors. AML cell lines HL-60, KG-1, OCI-AML3, and MOLM-14 released EVs with a peak diameter of approximately 80 nm in serum-free particle-reduced medium. We enriched EVs >100x using tangential flow filtration (TFF) and separated AML-derived soluble factors and cells in parallel. EVs were characterized by electron microscopy, immunoblotting, and flow cytometry, confirming the double-membrane morphology, purity and identity. AML-EVs showed significant enrichment of immune response and leukemia-related pathways in tandem mass-tag proteomics and a significant dose-dependent inhibition of T cell proliferation, which was not observed with AML cells or their soluble factors. Furthermore, AML-EVs dose-dependently reduced NK cell lysis of third-party K-562 leukemia targets. This emphasizes the peculiar role of AML-EVs in leukemia immune escape and indicates novel EV-based targets for therapeutic interventions.
    Keywords acute myeloid leukemia (AML) ; extracellular vesicles (EV) ; immunomodulation ; MISEV ; Biology (General) ; QH301-705.5
    Subject code 610
    Language English
    Publishing date 2021-11-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: The initial inflammatory response to bioactive implants is characterized by NETosis.

    Ljubomir Vitkov / Wolf-Dietrich Krautgartner / Astrid Obermayer / Walter Stoiber / Matthias Hannig / Michaela Klappacher / Dominik Hartl

    PLoS ONE, Vol 10, Iss 3, p e

    2015  Volume 0121359

    Abstract: Implants trigger an inflammatory response, which is important for osseointegration. Here we studied neutrophil extracellular trap (NET) release of human neutrophils in response to sandblasted large-grit acid etched (SLA) implants using fluorescent, ... ...

    Abstract Implants trigger an inflammatory response, which is important for osseointegration. Here we studied neutrophil extracellular trap (NET) release of human neutrophils in response to sandblasted large-grit acid etched (SLA) implants using fluorescent, confocal laser scanning and scanning electron microscopy. Our studies demonstrate that human neutrophils rapidly adhered to SLA surfaces, which triggered histone citrullination and NET release. Further studies showed that albumin or acetylsalicylic acid had no significant effects on the inflammatory response to SLA surfaces. In contrast to bioinert materials, which do not osseointegrate, the bioactivity of SLA surfaces is coupled with the ability to release NETs. Further investigations are necessary for clarifying the role of NETosis for osseointegration.
    Keywords Medicine ; R ; Science ; Q
    Language English
    Publishing date 2015-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: New aspects on the structure of neutrophil extracellular traps from chronic obstructive pulmonary disease and in vitro generation.

    Astrid Obermayer / Walter Stoiber / Wolf-Dietrich Krautgartner / Michaela Klappacher / Barbara Kofler / Peter Steinbacher / Ljubomir Vitkov / Fikreta Grabcanovic-Musija / Michael Studnicka

    PLoS ONE, Vol 9, Iss 5, p e

    2014  Volume 97784

    Abstract: Polymorphonuclear neutrophils have in recent years attracted new attention due to their ability to release neutrophil extracellular traps (NETs). These web-like extracellular structures deriving from nuclear chromatin have been depicted in ambiguous ... ...

    Abstract Polymorphonuclear neutrophils have in recent years attracted new attention due to their ability to release neutrophil extracellular traps (NETs). These web-like extracellular structures deriving from nuclear chromatin have been depicted in ambiguous roles between antimicrobial defence and host tissue damage. NETs consist of DNA strands of varying thickness and are decorated with microbicidal and cytotoxic proteins. Their principal structure has in recent years been characterised at molecular and ultrastructural levels but many features that are of direct relevance to cytotoxicity are still incompletely understood. These include the extent of chromatin decondensation during NET formation and the relative amounts and spatial distribution of the microbicidal components within the NET. In the present work, we analyse the structure of NETs found in induced sputum of patients with acutely exacerbated chronic obstructive pulmonary disease (COPD) using confocal laser microscopy and electron microscopy. In vitro induced NETs from human neutrophils serve for purposes of comparison and extended analysis of NET structure. Results demonstrate that COPD sputa are characterised by the pronounced presence of NETs and NETotic neutrophils. We provide new evidence that chromatin decondensation during NETosis is most extensive and generates substantial amounts of double-helix DNA in 'beads-on-a-string' conformation. New information is also presented on the abundance and location of neutrophil elastase (NE) and citrullinated histone H3 (citH3). NE occurs in high densities in nearly all non-fibrous constituents of the NETs while citH3 is much less abundant. We conclude from the results that (i) NETosis is an integral part of COPD pathology; this is relevant to all future research on the etiology and therapy of the disease; and that (ii) release of 'beads-on-a-string' DNA studded with non-citrullinated histones is a common feature of in vivo NETosis; this is of relevance to both the antimicrobial and the cytotoxic effects of NETs.
    Keywords Medicine ; R ; Science ; Q
    Subject code 612
    Language English
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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