Publications by authors named "Jasmin Knopf"

23 Publications

  • Page 1 of 1

Patients with COVID-19: in the dark-NETs of neutrophils.

Cell Death Differ 2021 May 24. Epub 2021 May 24.

First Department of Internal Medicine, Department of Medicine, University Hospital of Alexandroupolis, and Laboratory of Molecular Hematology, Democritus University of Thrace, Alexandroupolis, Greece.

SARS-CoV-2 infection poses a major threat to the lungs and multiple other organs, occasionally causing death. Until effective vaccines are developed to curb the pandemic, it is paramount to define the mechanisms and develop protective therapies to prevent organ dysfunction in patients with COVID-19. Individuals that develop severe manifestations have signs of dysregulated innate and adaptive immune responses. Emerging evidence implicates neutrophils and the disbalance between neutrophil extracellular trap (NET) formation and degradation plays a central role in the pathophysiology of inflammation, coagulopathy, organ damage, and immunothrombosis that characterize severe cases of COVID-19. Here, we discuss the evidence supporting a role for NETs in COVID-19 manifestations and present putative mechanisms, by which NETs promote tissue injury and immunothrombosis. We present therapeutic strategies, which have been successful in the treatment of immunο-inflammatory disorders and which target dysregulated NET formation or degradation, as potential approaches that may benefit patients with severe COVID-19.
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http://dx.doi.org/10.1038/s41418-021-00805-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8142290PMC
May 2021

Connection between Periodontitis-Induced Low-Grade Endotoxemia and Systemic Diseases: Neutrophils as Protagonists and Targets.

Int J Mol Sci 2021 Apr 28;22(9). Epub 2021 Apr 28.

Department of Internal Medicine 3-Rheumatology and Immunology, Universitätsklinikum Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), 91052 Erlangen, Germany.

Periodontitis is considered a promoter of many systemic diseases, but the signaling pathways of this interconnection remain elusive. Recently, it became evident that certain microbial challenges promote a heightened response of myeloid cell populations to subsequent infections either with the same or other pathogens. This phenomenon involves changes in the cell epigenetic and transcription, and is referred to as ''trained immunity''. It acts via modulation of hematopoietic stem and progenitor cells (HSPCs). A main modulation driver is the sustained, persistent low-level transmission of lipopolysaccharide from the periodontal pocket into the peripheral blood. Subsequently, the neutrophil phenotype changes and neutrophils become hyper-responsive and prone to boosted formation of neutrophil extracellular traps (NET). Cytotoxic neutrophil proteases and histones are responsible for ulcer formations on the pocket epithelium, which foster bacteremia and endoxemia. The latter promote systemic low-grade inflammation (SLGI), a precondition for many systemic diseases and some of them, e.g., atherosclerosis, diabetes etc., can be triggered by SLGI alone. Either reverting the polarized neutrophils back to the homeostatic state or attenuation of neutrophil hyper-responsiveness in periodontitis might be an approach to diminish or even to prevent systemic diseases.
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http://dx.doi.org/10.3390/ijms22094647DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8125370PMC
April 2021

Aggregated neutrophil extracellular traps occlude Meibomian glands during ocular surface inflammation.

Ocul Surf 2021 04 2;20:1-12. Epub 2021 Jan 2.

Department of Internal Medicine 3 - Rheumatology and Immunology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Universitätsklinikum Erlangen, Erlangen, Germany. Electronic address:

Purpose: Obstructive Meibomian gland dysfunction (MGD) is one of the leading causes of evaporative dry eye disease. Meibomian glands at the eyelid secrete lipids that prevent evaporation of the aqueous tear film. The pathogenesis of obstructive MGD is incompletely understood to date. Herein, we aim to investigate the pathogenesis of obstructive MGD using murine and human samples with various forms of ocular surface inflammation.

Method: The presence of Neutrophil extracellular Traps (NETs) was detected with immunofluorescence analysis of ocular surface discharge and biopsy samples from patients with blepharitis. Tear fluid from patients with MGD and blepharitis were evaluated for the presence of inflammatory mediators using bead based immunoassay. Murine model of allergic eye disease (AED) was performed to investigate the role of NETs in MG occlusion.

Results: we show that the ocular discharge from patients with blepharitis contains aggregated neutrophil extracellular traps (aggNETs). Furthermore, the ducts of human Meibomian glands affected by blepharitis were largely congested by aggNETs. Tear fluid from patients with MGD showed elevated neutrophil chemoattractants (C5a, IL6, IL8 and IL18). C5a and IL8 correlated with the degree of deficiency of tear fluid. In the murine model of allergic eye disease (AED), aggNETs accumulated in the MG leading to occlusion of their ducts and the retrograde pent-up of the fluid followed by acinar atrophy. Constraining aggNET formation by genetic or pharmacological inhibition of peptidyl arginine deiminase type 4 (PADI4) effectively reduced MG damage.

Conclusion: We conclude that aggNETs occlude MG causing MGD after ocular surface inflammation.
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http://dx.doi.org/10.1016/j.jtos.2020.12.005DOI Listing
April 2021

IgA2 Antibodies against SARS-CoV-2 Correlate with NET Formation and Fatal Outcome in Severely Diseased COVID-19 Patients.

Cells 2020 12 12;9(12). Epub 2020 Dec 12.

Deutsches Zentrum Immuntherapie (DZI), 91054 Erlangen, Germany.

Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) leads to an adaptive immune response in the host and the formation of anti-SARS-CoV-2 specific antibodies. While IgG responses against SARS-CoV-2 have been characterized quite well, less is known about IgA. IgA2 activates immune cells and induces inflammation and neutrophil extracellular trap (NET) formation which may contribute to organ injury and fatal outcome in SARS-CoV-2-infected patients. SARS-CoV-2 spike protein specific antibody levels were measured in plasma samples of 15 noninfected controls and 82 SARS-CoV-2-infected patients with no or mild symptoms, moderate symptoms (hospitalization) or severe disease (intensive care unit, ICU). Antibody levels were compared to levels of C-reactive protein (CRP) and circulating extracellular DNA (ecDNA) as markers for general inflammation and NET formation, respectively. While levels of SARS-CoV-2-specific IgG were similar in all patient groups, IgA2 antibodies were restricted to severe disease and showed the strongest discrimination between nonfatal and fatal outcome in patients with severe SARS-CoV-2 infection. While anti-SARS-CoV-2 IgG and IgA2 levels correlated with CRP levels in severely diseased patients, only anti-SARS-CoV-2 IgA2 correlated with ecDNA. These data suggest that the formation of anti-SARS-CoV-2 IgA2 during SARS-CoV-2 infection is a marker for more severe disease related to NET formation and poor outcome.
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http://dx.doi.org/10.3390/cells9122676DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7764693PMC
December 2020

NETs Are Double-Edged Swords with the Potential to Aggravate or Resolve Periodontal Inflammation.

Cells 2020 12 5;9(12). Epub 2020 Dec 5.

Department of Internal Medicine 3-Rheumatology and Immunology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU) and Universitätsklinikum Erlangen, 91054 Erlangen, Germany.

Periodontitis is a general term for diseases characterised by inflammatory destruction of tooth-supporting tissues, gradual destruction of the marginal periodontal ligament and resorption of alveolar bone. Early-onset periodontitis is due to disturbed neutrophil extracellular trap (NET) formation and clearance. Indeed, mutations that inactivate the cysteine proteases cathepsin C result in the massive periodontal damage seen in patients with deficient NET formation. In contrast, exaggerated NET formation due to polymorphonuclear neutrophil (PMN) hyper-responsiveness drives the pathology of late-onset periodontitis by damaging and ulcerating the gingival epithelium and retarding epithelial healing. Despite the gingival regeneration, periodontitis progression ends with almost complete loss of the periodontal ligament and subsequent tooth loss. Thus, NETs help to maintain periodontal health, and their dysregulation, either insufficiency or surplus, causes heavy periodontal pathology and edentulism.
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http://dx.doi.org/10.3390/cells9122614DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7762037PMC
December 2020

Neutrophil Extracellular Traps Promote the Development and Growth of Human Salivary Stones.

Cells 2020 09 22;9(9). Epub 2020 Sep 22.

Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Department of Internal Medicine 3, Universitätsklinikum Erlangen, Ulmenweg 18, 91054 Erlangen, Germany.

Salivary gland stones, or sialoliths, are the most common cause of the obstruction of salivary glands. The mechanism behind the formation of sialoliths has been elusive. Symptomatic sialolithiasis has a prevalence of 0.45% in the general population, is characterized by recurrent painful periprandial swelling of the affected gland, and often results in sialadenitis with the need for surgical intervention. Here, we show by the use of immunohistochemistry, immunofluorescence, computed tomography (CT) scans and reconstructions, special dye techniques, bacterial genotyping, and enzyme activity analyses that neutrophil extracellular traps (NETs) initiate the formation and growth of sialoliths in humans. The deposition of neutrophil granulocyte extracellular DNA around small crystals results in the dense aggregation of the latter, and the subsequent mineralization creates alternating layers of dense mineral, which are predominantly calcium salt deposits and DNA. The further agglomeration and appositional growth of these structures promotes the development of macroscopic sialoliths that finally occlude the efferent ducts of the salivary glands, causing clinical symptoms and salivary gland dysfunction. These findings provide an entirely novel insight into the mechanism of sialolithogenesis, in which an immune system-mediated response essentially participates in the physicochemical process of concrement formation and growth.
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http://dx.doi.org/10.3390/cells9092139DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7564068PMC
September 2020

Vascular occlusion by neutrophil extracellular traps in COVID-19.

EBioMedicine 2020 Aug 31;58:102925. Epub 2020 Jul 31.

Department of Internal Medicine 3, University Medical Center Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany; Deutsches Zentrum Immuntherapie (DZI), Erlangen, Germany.

Background: Coronavirus induced disease 2019 (COVID-19) can be complicated by severe organ damage leading to dysfunction of the lungs and other organs. The processes that trigger organ damage in COVID-19 are incompletely understood.

Methods: Samples were donated from hospitalized patients. Sera, plasma, and autopsy-derived tissue sections were examined employing flow cytometry, enzyme-linked immunosorbent assays, and immunohistochemistry.

Patient Findings: Here, we show that severe COVID-19 is characterized by a highly pronounced formation of neutrophil extracellular traps (NETs) inside the micro-vessels. Intravascular aggregation of NETs leads to rapid occlusion of the affected vessels, disturbed microcirculation, and organ damage. In severe COVID-19, neutrophil granulocytes are strongly activated and adopt a so-called low-density phenotype, prone to spontaneously form NETs. In accordance, markers indicating NET turnover are consistently increased in COVID-19 and linked to disease severity. Histopathology of the lungs and other organs from COVID-19 patients showed congestions of numerous micro-vessels by aggregated NETs associated with endothelial damage.

Interpretation: These data suggest that organ dysfunction in severe COVID-19 is associated with excessive NET formation and vascular damage.

Funding: Deutsche Forschungsgemeinschaft (DFG), EU, Volkswagen-Stiftung.
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http://dx.doi.org/10.1016/j.ebiom.2020.102925DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7397705PMC
August 2020

Neutrophil Extracellular Traps (NETs) in the Cerebrospinal Fluid Samples from Children and Adults with Central Nervous System Infections.

Cells 2019 12 23;9(1). Epub 2019 Dec 23.

Clinic of Infectious Diseases, Linköping University Hospital, SE-581 85 Linköping, Sweden.

Neutrophils operate as part of the innate defence in the skin and may eliminate the spirochaete via phagocytosis, oxidative bursts, and hydrolytic enzymes. However, their importance in Lyme neuroborreliosis (LNB) is unclear. Neutrophil extracellular trap (NET) formation, which is associated with the production of reactive oxygen species, involves the extrusion of the neutrophil DNA to form traps that incapacitate bacteria and immobilise viruses. Meanwhile, NET formation has recently been studied in pneumococcal meningitis, the role of NETs in other central nervous system (CNS) infections has previously not been studied. Here, cerebrospinal fluid (CSF) samples from clinically well-characterised children ( = 111) and adults ( = 64) with LNB and other CNS infections were analysed for NETs (DNA/myeloperoxidase complexes) and elastase activity. NETs were detected more frequently in the children than the adults ( = 0.01). NET presence was associated with higher CSF levels of CXCL1 ( < 0.001), CXCL6 ( = 0.007), CXCL8 ( = 0.003), CXCL10 ( < 0.001), MMP-9 ( = 0.002), TNF ( = 0.02), IL-6 ( < 0.001), and IL-17A ( = 0.03). NETs were associated with fever ( = 0.002) and correlated with polynuclear pleocytosis (r = 0.53, < 0.0001). We show that neutrophil activation and active NET formation occur in the CSF samples of children and adults with CNS infections, mainly caused by and neurotropic viruses. The role of NETs in the early phase of viral/bacterial CNS infections warrants further investigation.
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http://dx.doi.org/10.3390/cells9010043DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7016761PMC
December 2019

Updates on NET formation in health and disease.

Semin Arthritis Rheum 2019 12;49(3S):S43-S48

Friedrich Alexander University Erlangen-Nürnberg (FAU), Department of Internal Medicine 3 - Rheumatology and Immunology, Universitätsklinikum Erlangen, 90154 Erlangen, Germany.

Following a recent presentation at ATT Mallorca in May 2019, this paper gives insight into the current research of neutrophil extracellular traps (NETs) and their role in conditions of health and disease. Though NETs reportedly support disease progression and play a role in the development of autoimmune diseases, we argue that NETs are mandatory for the mammalian immune system. They are especially important to patrol and surveil outer and inner body surfaces and are capable to perform major anti-microbial activities. Neutrophils are the first cells to be recruited to wounds, where they form NETs and aggregated NETs (aggNETs). The latter close the wounds and are ever-present in skinfolds, where the integrity of the skin is impaired. On infected ocular surfaces NETs form an antimicrobial barrier, which prevents bacterial dissemination into the brain. In the oral cavity, NETs display anti-bacterial properties. Although NETs on internal body surfaces like ducts and vessels offer superficial surveillance, exaggerated aggNET formation may directly block vessels and ducts and thus cause thrombi and ductal occlusion, respectively. In the case of biliopancreatic ducts, clogging by aggNETs may even cause acute pancreatitis. Insufficient clearance of apoptotic remnants and NETs can lead to autoimmune diseases or unwanted, chronic inflammation. To prevent this, macrophages cloak dead cells, while apoptotic cells are cleared. We conclude that neutrophils, NETs and aggNETs can be considered double edged swords that orchestrate the innate immune response but carry the risk to precipitate autoimmunity and epithelial damage.
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http://dx.doi.org/10.1016/j.semarthrit.2019.09.011DOI Listing
December 2019

Towards a pro-resolving concept in systemic lupus erythematosus.

Semin Immunopathol 2019 11 6;41(6):681-697. Epub 2019 Nov 6.

Department of Internal Medicine 3 - Rheumatology and Immunology, Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Universitätsklinikum Erlangen, Erlangen, Germany.

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease with prominent chronic inflammatory aspects. SLE most often affects women (9:1) in childbearing age. The multifactorial nature of the etiopathogenesis of SLE involves a deficient clearance of dead and dying cells. This is supported by the occurrence of autoantibodies directed against autoantigens modified in dying and dead cells (dsDNA, high mobility group box 1 protein, apoptosis-associated chromatin modifications, e.g., histones H3-K27-me3; H2A/H4 AcK8,12,16; and H2B-AcK12) that are deposited in various tissues, including skin, kidneys, joints, muscles, and brain. The subsequent hyperinflammatory response often leads to irreparable tissue damage and organ destruction. In healthy individuals, dead and dying cells are rapidly removed by macrophages in an anti-inflammatory manner, referred to as efferocytosis. In SLE, extensive and prolonged cell death (apoptosis, necrosis, neutrophil extracellular trap (NET) formation) leads to autoantigens leaking out of the not cleared cell debris. These neo-epitopes are subsequently presented to B cells by follicular dendritic cells in the germinal centers of secondary lymphoid tissues conditioning the break of self-tolerance. Activation of autoreactive B cells and subsequent production of autoantibodies facilitate the formation of immune complexes (ICs) fueling the inflammatory response and leading to further tissue damage. ICs may also be ingested by phagocytes, which then produce further pro-inflammatory cytokines. These processes establish a vicious circle that leads to sustained inflammation. This review highlights the cell death-related events in SLE, the protagonists involved in SLE pathogenesis, the resolution of inflammation in various tissues affected in SLE, and explores strategies for intervention to restore hemostasis in a hyperinflammatory state.
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http://dx.doi.org/10.1007/s00281-019-00760-5DOI Listing
November 2019

Guidelines for the use of flow cytometry and cell sorting in immunological studies (second edition).

Eur J Immunol 2019 Oct;49(10):1457-1973

Flow Cytometry Laboratory, Institute of Molecular Toxicology and Pharmacology, Helmholtz Zentrum München, German Research Center for Environmental Health, München, Germany.

These guidelines are a consensus work of a considerable number of members of the immunology and flow cytometry community. They provide the theory and key practical aspects of flow cytometry enabling immunologists to avoid the common errors that often undermine immunological data. Notably, there are comprehensive sections of all major immune cell types with helpful Tables detailing phenotypes in murine and human cells. The latest flow cytometry techniques and applications are also described, featuring examples of the data that can be generated and, importantly, how the data can be analysed. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid, all written and peer-reviewed by leading experts in the field, making this an essential research companion.
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http://dx.doi.org/10.1002/eji.201970107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7350392PMC
October 2019

Aggregated NETs Sequester and Detoxify Extracellular Histones.

Front Immunol 2019 11;10:2176. Epub 2019 Sep 11.

Department of Medicine 3 - Rheumatology and Immunology, Universitätsklinikum Erlangen, Erlangen, Germany.

In response to various infectious and sterile stimuli neutrophils release chromatin decorated with bactericidal proteins, referred to as NETs. Their scaffolds are formed from chromatin fibers which display an apparent diameter of 15-17 nm and mainly consist from DNA (2 nm) and DNA-associated histones (11 nm). The NET-forming strands are thus not naked DNA but higher ordered chromatin structures. The histones may be released from the NET, especially if their tail arginines have been citrullinated. Several studies indicate that extracellular histones are toxic for mammalian epithelia and endothelia and contribute to the microvascular dysfunction observed e.g., in patients suffering from autoimmune diseases or sepsis. NETs formed at sites of very high neutrophil densities tend to clump and form fairly stable enzymatically active aggregates, referred to as aggNETs. The latter are endowed with a bunch of enzymes that cleave, bind, and/or modify autologous as well as foreign macromolecules. The tight binding of the serine proteases to the matrix precludes the spread of these toxic enzymes into the tissue but still allows the access of soluble inflammatory mediators to the enzymatic active internal surfaces of the NETs where they are degraded. Here, we describe that externally added histones are removed from culture supernatants of aggNETs. We will address the fate of the histones and discuss the feature on the background of neutrophil-driven diseases and the resolution of inflammation.
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http://dx.doi.org/10.3389/fimmu.2019.02176DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6749074PMC
October 2020

Treatment with DNases rescues hidden neutrophil elastase from aggregated NETs.

J Leukoc Biol 2019 12 2;106(6):1359-1366. Epub 2019 Sep 2.

Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department of Internal Medicine 3-Rheumatology and Immunology, Universitätsklinikum Erlangen, Erlange, Germany.

The release of neutrophil extracellular traps (NETs) is one of the weapons neutrophils have in their armory. NETs consist of extracellular chromatin fibers decorated with a plethora of cytoplasmic and granular proteins, such as the antimicrobial serine protease neutrophil elastase (NE). Because the first description of NETs as beneficial to the host, reports on their double-faced role in health and disease have considerably increased recently. On one hand, NETs reportedly trap and kill bacteria and also participate in the resolution of the acute inflammation associated with infection and with tissue damage. On the other hand, numerous negative aspects of NETs contribute to the etiopathogenesis of autoimmune disorders. Employing soluble and solid fluorescent substrates, we demonstrate the interaction of NE with aggregated NETs (aggNETs), the limitation of its enzymatic activity and the containment of the enzyme from surrounding tissues. These events prevent the spread of inflammation and tissue damage. The detection of DNase 1-dependent elevation of NE activity attests the continuous presence of patrolling neutrophils forming NETs and aggNETs even under conditions physiologic conditions.
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http://dx.doi.org/10.1002/JLB.3AB0918-370RDOI Listing
December 2019

Neutrophil Extracellular Traps Initiate Gallstone Formation.

Immunity 2019 09 15;51(3):443-450.e4. Epub 2019 Aug 15.

Friedrich Alexander University Erlangen-Nürnberg (FAU), Department of Internal Medicine 3 - Rheumatology and Immunology, Universitätsklinikum Erlangen, 90154 Erlangen, Germany. Electronic address:

The presence of gallstones (cholelithiasis) is a highly prevalent and severe disease and one of the leading causes of hospital admissions worldwide. Due to its substantial health impact, we investigated the biological mechanisms that lead to the formation and growth of gallstones. We show that gallstone assembly essentially requires neutrophil extracellular traps (NETs). We found consistent evidence for the presence of NETs in human and murine gallstones and describe an immune-mediated process requiring activation of the innate immune system for the formation and growth of gallstones. Targeting NET formation via inhibition of peptidyl arginine deiminase type 4 or abrogation of reactive oxygen species (ROS) production, as well as damping of neutrophils by metoprolol, effectively inhibit gallstone formation in vivo. Our results show that after the physicochemical process of crystal formation, NETs foster their assembly into larger aggregates and finally gallstones. These insights provide a feasible therapeutic concept to prevent cholelithiasis in patients at risk.
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http://dx.doi.org/10.1016/j.immuni.2019.07.002DOI Listing
September 2019

NOX2 mediates quiescent handling of dead cell remnants in phagocytes.

Redox Biol 2019 09 20;26:101279. Epub 2019 Jul 20.

Department of Medicine 3, Rheumatology and Immunology, Friedrich Alexander-University Erlangen-Nürnberg, Universitätsklinikum Erlangen, Erlangen, Germany. Electronic address:

The phagocyte NADPH oxidase (the NOX2 complex) generates superoxide, the precursor to reactive oxygen species (ROS). ROS possess both antimicrobial and immunoregulatory function. Inactivating mutations in alleles of the NOX2 complex cause chronic granulomatous disease (CGD), characterized by an enhanced susceptibility to infections and autoimmune diseases such as Systemic lupus erythematosus (SLE). The latter is characterized by insufficient removal of dead cells, resulting in an autoimmune response against components of the cell's nucleus when non-cleared apoptotic cells lose their membrane integrity and present autoantigenic molecules in an inflammatory context. Here we aimed to shed light on the role of the NOX2 complex in handling of secondary necrotic cells (SNECs) and associated consequences for inflammation and autoimmunity during lupus. We show that individuals with SLE and CGD display accumulation of SNECs in blood monocytes and neutrophils. In a CGD phenotypic mouse strain (Ncf1** mice) build-up of SNECs in Ly6C blood monocytes was connected with a delayed degradation of the phagosomal cargo and accompanied by production of inflammatory mediators. Treatment with HO or activators of ROS-formation reconstituted phagosomal abundance of SNECs to normal levels. Induction of experimental lupus further induced increased antibody-dependent uptake of SNECs into neutrophils. Lupus-primed Ncf1** neutrophils took up more SNECs than wild type neutrophils, whereas SNEC-accumulation in regulatory Ly6C monocytes was lower in Ncf1**mice. We deduce that the inflammatory rerouting of immune-stimulatory necrotic material into inflammatory phagocyte subsets contributes to the connection between low ROS production by the NOX2 complex and SLE.
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http://dx.doi.org/10.1016/j.redox.2019.101279DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6669319PMC
September 2019

Active NET formation in Libman-Sacks endocarditis without antiphospholipid antibodies: A dramatic onset of systemic lupus erythematosus.

Autoimmunity 2018 09 28;51(6):310-318. Epub 2018 Oct 28.

b Division of Neuro and Inflammation Sciences, Department of Clinical and Experimental Medicine , Linköping University , Linköping , Sweden.

Although neutrophil extracellular traps (NETs) have been highlighted in several systemic inflammatory diseases, their clinical correlates and potential pathological role remain obscure. Herein, we describe a dramatic onset of systemic lupus erythematosus (SLE) with clear-cut pathogenic implications for neutrophils and NET formation in a young woman with cardiac (Libman-Sacks endocarditis) and central nervous system (psychosis and seizures) involvement. Despite extensive search, circulating antiphospholipid autoantibodies, a hallmark of Libman-Sacks endocarditis, could not be detected. Instead, we observed active NET formation in the tissue of the mitral valve, as well as in the circulation. Levels of NET remnants were significantly higher in serially obtained sera from the patient compared with sex-matched blood donors (p = .0011), and showed a non-significant but substantial correlation with blood neutrophil counts (r = 0.65, p = .16). The specific neutrophil elastase activity measured in serum seemed to be modulated by the provided immunosuppressive treatment. In addition, we found anti-Ro60/SSA antibodies in the cerebrospinal fluid of the patient but not NET remnants or increased elastase activity. This case illustrates that different disease mechanisms mediated via autoantibodies can occur simultaneously in SLE. NET formation with release of cytotoxic NET remnants is a candidate player in the pathogenesis of this non-canonical form of Libman-Sacks endocarditis occurring in the absence of traditional antiphospholipid autoantibodies. The case description includes longitudinal results with clinical follow-up data and a discussion of the potential roles of NETs in SLE.
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http://dx.doi.org/10.1080/08916934.2018.1514496DOI Listing
September 2018

Autoimmune, rheumatic, chronic inflammatory diseases: Neutrophil extracellular traps on parade.

Autoimmunity 2018 09 29;51(6):281-287. Epub 2018 Oct 29.

a Department of Internal Medicine 3- Rheumatology and Immunology , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) and Universitätsklinikum Erlangen , Erlangen , Germany.

Rheumatic diseases are a group of inflammatory conditions that affect joints and connective tissues and are often accompanied by pain and restriction of motility. In many of these diseases, autoantibodies develop that react with molecules/structures commonly found hidden in neutrophils. Neutrophil extracellular trap (NET) formation and release is considered a defense mechanism against pathogens or endogenous danger signals and it has been associated with initial inflammatory responses. NETs are also endowed with an important resolution potential based on its intrinsic enzymatic activity, but in the case they are not timely removed from the crime scene they might modulate subsequent immune responses and contribute to the pathogenesis of chronic inflammatory diseases. In this review, we will summarize the actual knowledge about the multifaceted roles of NETs in the etiology and pathogenesis of rheumatic autoimmune diseases.
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http://dx.doi.org/10.1080/08916934.2018.1519804DOI Listing
September 2018

Long noncoding RNA HOTAIR is upregulated in an aggressive subgroup of gastrointestinal stromal tumors (GIST) and mediates the establishment of gene-specific DNA methylation patterns.

Genes Chromosomes Cancer 2018 11 24;57(11):584-597. Epub 2018 Sep 24.

Diagnostic Molecular Pathology, Institute of Pathology, Friedrich Alexander University, Erlangen, Germany.

Aberrant alterations of DNA methylation are common events in oncogenesis. The origin of cancer-associated epigenetic defects is of interest for mechanistic understanding of malignant transformation and-in the long run-therapeutic modulation of DNA methylation in a locus-specific manner. Given the ability of certain long noncoding RNAs to operate as an interface between DNA and the epigenetic modification machinery which can interact with DNA methyltransferases, we hypothesized-considering HOTAIR as an example-that this transcript may contribute to gene specificity of DNA methylation. Using gastrointestinal stromal tumors (GISTs, n = 67) as a model, we confirmed upregulation of HOTAIR in tumors with high risk of recurrence and showed high abundance of the transcript in GIST cell lines. HOTAIR knockdown in GIST-T1 cells triggered transcriptional response of genes involved in the organization and disassembly of the extracellular matrix and, notably, induced global locus-specific alterations of DNA methylation patterns. Hypomethylation was induced at a total of 507 CpG sites, whereas 382 CpG dinucleotides underwent gain of methylation upon HOTAIR depletion. Importantly, orchestrated gain or loss of methylation at multiple individual CpG sites was shown for cancer-related DPP4, RASSF1, ALDH1A3, and other targets. Collectively, our data indicate that HOTAIR enables target specificity of DNA methylation in GIST and is capable of dual (hypo- and hypermethylation) regulation by a yet to be defined mechanism. The results further suggest the feasibility of manipulating DNA methylation in a targeted manner and are of interest in the context of epigenetic cancer therapy.
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http://dx.doi.org/10.1002/gcc.22672DOI Listing
November 2018

Autoantibodies Recognizing Secondary NEcrotic Cells Promote Neutrophilic Phagocytosis and Identify Patients With Systemic Lupus Erythematosus.

Front Immunol 2018 7;9:989. Epub 2018 May 7.

Department of Internal Medicine 3 - Rheumatology and Immunology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) and Universitätsklinikum Erlangen, Erlangen, Germany.

Deficient clearance of apoptotic cells reportedly contributes to the etiopathogenesis of the autoimmune disease systemic lupus erythematosus (SLE). Based on this knowledge, we developed a highly specific and sensitive test for the detection of SLE autoantibodies (AAb) utilizing secondary NEcrotic cell (SNEC)-derived material as a substrate. The goal of the present study was to validate the use of SNEC as an appropriate antigen for the diagnosis of SLE in large cohort of patients. We confirmed the presence of apoptotically modified autoantigens on SNEC (dsDNA, high mobility group box 1 protein, apoptosis-associated chromatin modifications, e.g., histones H3-K27-me3; H2A/H4 AcK8,12,16; and H2B-AcK12). Anti-SNEC AAb were measured in the serum of 155 patients with SLE, 89 normal healthy donors (NHD), and 169 patients with other autoimmune connective tissue diseases employing SNEC-based indirect enzyme-linked immunosorbent assay (SNEC ELISA). We compared the test performance of SNEC ELISA with the routine diagnostic tests dsDNA Farr radioimmunoassay (RIA) and nucleosome-based ELISA (). SNEC ELISA distinguished patients with SLE with a specificity of 98.9% and a sensitivity of 70.6% from NHD clearly surpassing RIA and . In contrast to the other tests, SNEC ELISA significantly discriminated patients with SLE from patients with rheumatoid arthritis, primary anti-phospholipid syndrome, spondyloarthropathy, psoriatic arthritis, and systemic sclerosis. A positive test result in SNEC ELISA significantly correlated with serological variables and reflected the uptake of opsonized SNEC by neutrophils. This stresses the relevance of SNECs in the pathogenesis of SLE. We conclude that SNEC ELISA allows for the sensitive detection of pathologically relevant AAb, enabling its diagnostic usage. A positive SNEC test reflects the opsonization of cell remnants by AAb, the neutrophil recruitment to tissues, and the enhancement of local and systemic inflammatory responses.
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http://dx.doi.org/10.3389/fimmu.2018.00989DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5949357PMC
July 2019

Low amounts of bisecting glycans characterize cerebrospinal fluid-borne IgG.

J Neuroimmunol 2018 07 16;320:19-24. Epub 2018 Apr 16.

Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Department of Internal Medicine 3, Rheumatology and Immunology, Universitätsklinikum Erlangen, Erlangen, Germany. Electronic address:

Immunoglobulin G (IgG) harbors a conserved N-glycosylation site which is important for its effector functions. Changes in glycosylation of IgG occur in many autoimmune diseases but also in physiological conditions. Therefore, the glycosylation pattern of serum IgG is well characterized. However, limited data is available on the glycosylation pattern of IgG in cerebrospinal fluid (CSF) compared to serum. Here, we report significantly reduced levels of bisected glycans in CSF IgG. Galactosylation and sialylation of IgG4 also differed significantly. Therefore, we propose a common mechanism mediating glycosylation changes of IgG at the transition from serum to CSF in steady state conditions.
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http://dx.doi.org/10.1016/j.jneuroim.2018.04.010DOI Listing
July 2018

Oxidative Burst-Dependent NETosis Is Implicated in the Resolution of Necrosis-Associated Sterile Inflammation.

Front Immunol 2016 1;7:557. Epub 2016 Dec 1.

Department of Internal Medicine 3 - Rheumatology and Immunology, Universitätsklinikum Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg , Erlangen , Germany.

Necrosis is associated with a profound inflammatory response. The regulation of necrosis-associated inflammation, particularly the mechanisms responsible for resolution of inflammation is incompletely characterized. Nanoparticles are known to induce plasma membrane damage and necrosis followed by sterile inflammation. We observed that injection of metabolically inert nanodiamonds resulted in paw edema in WT and mice. However, while inflammation quickly resolved in WT mice, it persisted over several weeks in mice indicating failure of resolution of inflammation. Mechanistically, NOX2-dependent reactive oxygen species (ROS) production and formation of neutrophil extracellular traps were essential for the resolution of necrosis-induced inflammation: hence, by evaluating the fate of the particles at the site of inflammation, we observed that mice deficient in NADPH-dependent ROS failed to generate granulation tissue therefore being unable to trap the nanodiamonds. These data suggest that NOX2-dependent NETosis is crucial for preventing the chronification of the inflammatory response to tissue necrosis by forming NETosis-dependent barriers between the necrotic and healthy surrounding tissue.
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http://dx.doi.org/10.3389/fimmu.2016.00557DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5131011PMC
December 2016

Neutrophils and neutrophil extracellular traps orchestrate initiation and resolution of inflammation.

Clin Exp Rheumatol 2016 Jul-Aug;34(4 Suppl 98):6-8. Epub 2016 Jul 29.

Department of Internal Medicine 3, University of Erlangen-Nuremberg, Erlangen, Germany.

Neutrophils, the most abundant leukocytes in the human body, are considered to be the first line of defense in the fight against microorganisms. In this fight neutrophils employ weaponry such as reactive oxygen species produced via the NADPH oxidase complex 2 together with the release of intracellular granules containing antimicrobial agents. The discovery that activated neutrophils release decondensed chromatin as DNase-sensitive neutrophil extracellular traps (NETs) lead to a renewed interest in these leukocytes and the function of NETs in vivo. In this review, we will focus on desirable as well as detrimental features of NETs by the example of gout and pancreatitis. In our models we observed that neutrophils drive the initiation of inflammation and are required for the resolution of inflammation.
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December 2016

Paediatric and adult soft tissue sarcomas with NTRK1 gene fusions: a subset of spindle cell sarcomas unified by a prominent myopericytic/haemangiopericytic pattern.

J Pathol 2016 Apr;238(5):700-10

Institute of Pathology, University Hospital, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen, Germany.

Neoplasms with a myopericytomatous pattern represent a morphological spectrum of lesions encompassing myopericytoma of the skin and soft tissue, angioleiomyoma, myofibromatosis/infantile haemangiopericytoma and putative neoplasms reported as malignant myopericytoma. Lack of reproducible phenotypic and genetic features of malignant myopericytic neoplasms have prevented the establishment of myopericytic sarcoma as an acceptable diagnostic category. Following detection of a LMNA-NTRK1 gene fusion in an index case of paediatric haemangiopericytoma-like sarcoma by combined whole-genome and RNA sequencing, we identified three additional sarcomas harbouring NTRK1 gene fusions, termed 'spindle cell sarcoma, NOS with myo/haemangiopericytic growth pattern'. The patients were two children aged 11 months and 2 years and two adults aged 51 and 80 years. While the tumours of the adults were strikingly myopericytoma-like, but with clear-cut atypical features, the paediatric cases were more akin to infantile myofibromatosis/haemangiopericytoma. All cases contained numerous thick-walled dysplastic-like vessels with segmental or diffuse nodular myxohyaline myo-intimal proliferations of smooth muscle actin-positive cells, occasionally associated with thrombosis. Immunohistochemistry showed variable expression of smooth muscle actin and CD34, but other mesenchymal markers, including STAT6, were negative. This study showed a novel variant of myo/haemangiopericytic sarcoma with recurrent NTRK1 gene fusions. Given the recent introduction of a novel therapeutic approach targeting NTRK fusion-positive neoplasms, recognition of this rare but likely under-reported sarcoma variant is strongly encouraged.
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http://dx.doi.org/10.1002/path.4701DOI Listing
April 2016
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