scholarly journals A transgenic zebrafish line for in vivo visualisation of neutrophil myeloperoxidase

2018 ◽  
Author(s):  
Kyle D. Buchan ◽  
Tomasz K. Prajsnar ◽  
Nikolay V. Ogryzko ◽  
Nienke W.M. de Jong ◽  
Michiel van Gent ◽  
...  
Keyword(s):  
Hypochlorous Acid ◽  
Neutrophil Migration ◽  
Subcellular Location ◽  
Human Neutrophils ◽  
Transgenic Zebrafish ◽  
Inflammatory Conditions ◽  
Granular Dynamics ◽  
Increased Risk ◽  
Potential Applications

AbstractThe neutrophil enzyme myeloperoxidase (MPO) is a major enzyme made by neutrophils to generate antimicrobial and immunomodulatory compounds, notably hypochlorous acid (HOCl), amplifying their capacity for destroying pathogens and regulating inflammation. Despite its roles in innate immunity, the importance of MPO in preventing infection is unclear, as individuals with MPO deficiency are asymptomatic with the exception of an increased risk of candidiasis. Dysregulation of MPO activity is also linked with inflammatory conditions such as atherosclerosis, emphasising a need to understand the roles of the enzyme in greater detail. Consequently, new tools for investigating granular dynamics in vivo can provide useful insights into how MPO localises within neutrophils, aiding understanding of its role in preventing and exacerbating disease. The zebrafish is a powerful model for investigating the immune system in vivo, as it is genetically tractable, and optically transparent.To visualise MPO activity within zebrafish neutrophils, we created a genetic construct that expresses human MPO as a fusion protein with a C-terminal fluorescent tag, driven by the neutrophil-specific promoter lyz. After introducing the construct into the zebrafish genome by Tol2 transgenesis, we established the Tg(lyz:Hsa.MPO-mEmerald,cmlc2:EGFP)sh496 line, and confirmed transgene expression in zebrafish neutrophils. We observed localisation of MPO-mEmerald within a subcellular location resembling neutrophil granules, mirroring MPO in human neutrophils. In Spotless (mpxNL144) larvae - which express a non-functional zebrafish myeloperoxidase - the MPO-mEmerald transgene does not disrupt neutrophil migration to sites of infection or inflammation, suggesting that it is a suitable line for the study of neutrophil granule function.We present a new transgenic line that can be used to investigate neutrophil granule dynamics in vivo without disrupting neutrophil behaviour, with potential applications in studying processing and maturation of MPO during development.

scholarly journals A CRISPR/Cas9 vector system for neutrophil-specific gene disruption in zebrafish

2020 ◽  
Author(s):  
Yueyang Wang ◽  
Alan Y. Hsu ◽  
Eric M. Walton ◽  
Ramizah Syahirah ◽  
Tianqi Wang ◽  
...  
Keyword(s):  
Cell Motility ◽  
Neutrophil Migration ◽  
Transgenic Fish ◽  
Subcellular Location ◽  
Vector System ◽  
Specific Gene ◽  
Tissue Specific ◽  
Biological Studies

AbstractTissue-specific knockout techniques are widely applied in biological studies to probe the tissue-specific roles of specific genes in physiology, development, and disease. CRISPR/Cas9 is a widely used technology to perform fast and efficient genome editing in vitro and in vivo. Here, we report a robust CRISPR-based gateway system for tissue-specific gene inactivation in zebrafish. A transgenic fish line expressing Cas9 under the control of a neutrophil-restricted promoter was constructed. As proof of principle, we transiently disrupted rac2 or cdk2 in neutrophils using plasmids driving the expression of sgRNAs from U6 promoters. Loss of the rac2 or cdk2 gene in neutrophils resulted in significantly decreased cell motility, which could be restored by re-expressing Rac2 or Cdk2 in neutrophils in the corresponding knockout background. The subcellular location of Rac activation and actin structure and stress in the context of neutrophil migration was determined in both the wild-type and rac2 knockout neutrophils in vivo. In addition, we evaluated an alternative approach where the Cas9 protein is ubiquitously expressed while the sgRNA is processed by ribozymes and expressed in a neutrophil-restricted manner. Cell motility was also reduced upon rac2 sgRNA expression. Together, our work provides a potent tool that can be used to advance the utility of zebrafish in identification and characterization of gene functions in neutrophils.

scholarly journals Mast Cell Tryptase Potentiates Neutrophil Extracellular Trap Formation

2021 ◽  
pp. 1-14
Author(s):  
Gunnar Pejler ◽  
Sultan Alanazi ◽  
Mirjana Grujic ◽  
Jeremy Adler ◽  
Anna-Karin Olsson ◽  
...  
Keyword(s):  
Neutrophil Extracellular Trap ◽  
Human Neutrophils ◽  
Functional Communication ◽  
Extracellular Milieu ◽  
Extracellular Traps ◽  
Inflammatory Conditions ◽  
Histone 3 ◽  
Activated Neutrophils ◽  
Core Histones

Previous research has indicated an intimate functional communication between mast cells (MCs) and neutrophils during inflammatory conditions, but the nature of such communication is not fully understood. Activated neutrophils are known to release DNA-containing extracellular traps (neutrophil extracellular traps [NETs]) and, based on the known ability of tryptase to interact with negatively charged polymers, we here hypothesized that tryptase might interact with NET-contained DNA and thereby regulate NET formation. In support of this, we showed that tryptase markedly enhances NET formation in phorbol myristate acetate-activated human neutrophils. Moreover, tryptase was found to bind vividly to the NETs, to cause proteolysis of core histones and to cause a reduction in the levels of citrullinated histone-3. Secretome analysis revealed that tryptase caused increased release of numerous neutrophil granule compounds, including gelatinase, lactoferrin, and myeloperoxidase. We also show that DNA can induce the tetrameric, active organization of tryptase, suggesting that NET-contained DNA can maintain tryptase activity in the extracellular milieu. In line with such a scenario, DNA-stabilized tryptase was shown to efficiently degrade numerous pro-inflammatory compounds. Finally, we showed that tryptase is associated with NET formation in vivo in a melanoma setting and that NET formation in vivo is attenuated in mice lacking tryptase expression. Altogether, these findings reveal that NET formation can be regulated by MC tryptase, thus introducing a novel mechanism of communication between MCs and neutrophils.

A method for high-purity isolation of neutrophil granulocytes for functional cell migration assays

2019 ◽  
Vol 44 (6) ◽  
pp. 810-821
Author(s):  
Edibe Avci ◽  
Yeliz Z. Akkaya-Ulum ◽  
Digdem Yoyen-Ermis ◽  
Gunes Esendagli ◽  
Banu Balci-Peynircioglu
Keyword(s):  
Flow Cytometry ◽  
Cell Migration ◽  
Neutrophil Migration ◽  
Cost Effective ◽  
In Vitro Assays ◽  
Human Neutrophils ◽  
Neutrophil Granulocytes ◽  
Inflammatory Conditions ◽  
Migration Analysis

Abstract Background Neutrophil-mediated killing of pathogens is one of the most significant functions of the primary defense of the host. Neutrophil activity and migration play a key role in inflammatory conditions. To gain insights into the interactions between neutrophils and neutrophil migration-related disorders, a large number of sophisticated methods have been developed. The technical limitations of isolating highly purified neutrophil populations, minimizing both cell death and activation during the isolation process, and the short lifespan of neutrophils present challenges for studying specific functions of neutrophils in vitro. In this study, we aimed to evaluate a separation medium-based density gradient method to obtain highly purified neutrophil populations and combined this protocol with a model for studying neutrophil migration in-vitro. Materials and methods Human granulocytes were isolated using Lympholyte-poly solution. The purity and viability of isolated neutrophils were assessed by flow cytometry and morphological analysis. Neutrophil activation was confirmed by immunocytochemistry. Lastly, filter assay was performed to measure neutrophil chemotaxis. Results and discussion All validation experiments revealed that this method was capable of generating a highly purified neutrophil population for further functional in-vitro assays. Consequently, this study demonstrates a quick, cost effective, and easy-to-follow model, and may be a significant alternative to isolation methods that need extra subsequent steps such as flow cytometry-based cell sorting for reaching highly purified neutrophil population. Conclusion The suggested combination of methods for the isolation and cell migration analysis of human neutrophils is highly recommended to use for disease models involving neutrophil migration such as autoinflammatory disorders.

scholarly journals Attachment to fibronectin or vitronectin makes human neutrophil migration sensitive to alterations in cytosolic free calcium concentration.

1991 ◽  
Vol 112 (1) ◽  
pp. 149-158 ◽  
Author(s):  
P W Marks ◽  
B Hendey ◽  
F R Maxfield
Keyword(s):  
Calcium Concentration ◽  
Neutrophil Migration ◽  
Human Neutrophils ◽  
Free Calcium ◽  
Cytosolic Free Calcium ◽  
Coated Glass ◽  
Free Calcium Concentration ◽  
Cytosolic Free Calcium Concentration ◽  
Migration Of Cells

Transient increases in cytosolic free calcium concentration, [Ca2+]i, appear to be required for the migration of human neutrophils on poly-D-lysine-coated glass in the presence of dilute serum (Marks, P. W., and F. R. Maxfield. 1990. J. Cell Biol. 110:43-52). In contrast, no requirement for [Ca2+]i transients exists when neutrophils migrate on albumin-coated glass in the absence of serum. To determine the mechanism that necessitates [Ca2+]i transients on poly-D-lysine in the presence of serum, migration was examined on substrates consisting of purified adhesive glycoproteins. In the absence of external Ca2+, a treatment which causes the cessation of [Ca2+]i transients, migration on fibronectin (fn) and vitronectin (vn) was significantly inhibited. Migration was also inhibited in Ca2(+)-buffered cells on these substrates, indicating that this effect was the result of an alteration of [Ca2+]i. In the absence of external Ca2+, the inhibition of migration on fn or vn was more pronounced when soluble fn or vn was added to cells migrating on these substrates. This effect of soluble adhesive glycoprotein was specific: in the absence of external Ca2+, soluble fn did not affect the migration of cells on vn, and soluble vn did not affect the migration on fn. No additional inhibition of migration was observed in Ca2(+)-buffered cells with the addition of soluble adhesive glycoprotein. These data indicate that [Ca2+]i transients are involved in continued migration of human neutrophils on fn or vn, proteins which are part of the extracellular matrix that neutrophils encounter in vivo.

scholarly journals Tumour necrosis factor-alpha and interleukin-8 inhibit neutrophil migration in vitro and in vivo

1992 ◽  
Vol 1 (6) ◽  
pp. 397-401 ◽  
Author(s):  
F. Q. Cunha ◽  
W. M. S. Cunha Tamashiro
Keyword(s):  
Tumour Necrosis Factor ◽  
Tumour Necrosis ◽  
Neutrophil Migration ◽  
Tumour Necrosis Factor Alpha ◽  
Interleukin 8 ◽  
Human Neutrophils ◽  
Necrosis Factor Alpha ◽  
Factor Alpha ◽  
Necrosis Factor

Pretreatment of human neutrophils with recombinant tumour necrosis factor-alpha (rTNF-α) and/or interleukin-8 (rIL-8), but not with either transforming growth factor-beta, interleukin-6 or interferon-gamma, rendered these cells less responsive to FMLP, in microchemotaxis assays. This inhibitory effect was dose dependent and more powerful when neutrophils were pretreated with a mixture of both cytokines. Intravenous injection of human rIL-8 (hrIL-8) and/or murine rTNF-α (mrTNF-α) also significantly reduced in vivo neutrophil migration into peritoneal cavities of rats stimulated with carrageenan. These data suggest that the defect in neutrophil migration during septicaemia or endotoxaemia may be the result of the continuous release of IL-8 and TNF-α into the circulation. Thus, either the selective control or blockade of releasing of these cytokines as well as of its effects on neutrophils may be clinically useful in reestablishing the cell defence mechanisms.

scholarly journals Human neutrophils are not activated by Zika virus but reduce the infection of susceptible cells

2021 ◽  
Author(s):  
Juliana Bernardi Aggio ◽  
Bárbara Nery Porto ◽  
Claudia Nunes Duarte dos Santos ◽  
Ana Luiza Pamplona Mosimann ◽  
Pryscilla Fanini Wowk
Keyword(s):  
Zika Virus ◽  
Neutrophil Migration ◽  
A549 Cells ◽  
Human Neutrophils ◽  
Cell Contact ◽  
Target Cells ◽  
Zikv Infection ◽  
Host Interaction

Zika virus (ZIKV) emergence highlighted the need for a deeper understanding on virus-host interaction to pave the development of antiviral therapies. The present work aimed to address the response of neutrophils during ZIKV infection. Neutrophils are an important effector cell in innate immunity involved in the host response to neurotropic arboviruses. Our results indicate that human neutrophils were not permissive to Asian or African ZIKV strains replication. Indeed, after stimulation with ZIKV, neutrophils were not primed against the virus as evaluated by the absence of CD11b modulation, secretion of inflammatory cytokines and granule content, production of reactive oxygen species and neutrophil extracellular traps formation. Overall, neutrophils did not affect ZIKV infectivity. Moreover, ZIKV infection of primary innate immune cells in vitro did not trigger neutrophil migration. However, neutrophil co-cultured with ZIKV susceptible cells (A549) resulted in lower frequencies of infection on A549 cells by cell-to-cell contact. In vivo, neutrophil depletion from immunocompetent mice did not affect ZIKV spreading to the draining lymph nodes. The data suggest human neutrophils do not play a per se antiviral role against ZIKV, but these cells might participate in an infected environment shaping the ZIKV infection in other target cells.

scholarly journals Pioneer neutrophils release chromatin within in vivo swarms

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Hannah M Isles ◽  
Catherine A Loynes ◽  
Sultan Alasmari ◽  
Fu Chuen Kon ◽  
Katherine M Henry ◽  
...  
Keyword(s):  
Tissue Injury ◽  
Damage Model ◽  
Neutrophil Migration ◽  
Initial Step ◽  
Transgenic Zebrafish ◽  
In Vivo Models ◽  
Essential Components ◽  
Cellular Components

Neutrophils are rapidly recruited to inflammatory sites where their coordinated migration forms clusters, a process termed neutrophil swarming. The factors that modulate early stages of neutrophil swarming are not fully understood, requiring the development of new in vivo models. Using transgenic zebrafish larvae to study endogenous neutrophil migration in a tissue damage model, we demonstrate that neutrophil swarming is a conserved process in zebrafish immunity, sharing essential features with mammalian systems. We show that neutrophil swarms initially develop around an individual pioneer neutrophil. We observed the violent release of extracellular cytoplasmic and nuclear fragments by the pioneer and early swarming neutrophils. By combining in vitro and in vivo approaches to study essential components of neutrophil extracellular traps (NETs), we provide in-depth characterisation and high-resolution imaging of the composition and morphology of these release events. Using a photoconversion approach to track neutrophils within developing swarms, we identify that the fate of swarm-initiating pioneer neutrophils involves extracellular chromatin release and that the key NET components gasdermin, neutrophil elastase, and myeloperoxidase are required for the swarming process. Together our findings demonstrate that release of cellular components by pioneer neutrophils is an initial step in neutrophil swarming at sites of tissue injury.

scholarly journals In vitro and in vivo modulation of NADPH-oxidase activity and reactive oxygen species production in human neutrophils by alpha-1 antitrypsin

2021 ◽  
pp. 00234-2021
Author(s):  
Padraig Hawkins ◽  
Thomas McEnery ◽  
Claudie Gabillard-Lefort ◽  
David A Bergin ◽  
Bader Alfawaz ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Plasma Membrane ◽  
Nadph Oxidase ◽  
Ex Vivo ◽  
Human Neutrophils ◽  
Driving Mechanism ◽  
Increased Risk ◽  
Alpha 1 Antitrypsin

Oxidative stress from innate immune cells is a driving mechanism that underlies COPD pathogenesis. Individuals with alpha-1 antitrypsin (AAT) deficiency (AATD) have a dramatically increased risk of developing COPD. To understand this further, the aim of this study was to investigate whether AATD presents with altered neutrophil NADPH-oxidase activation, due to the specific lack of plasma AAT. Experiments were performed using circulating neutrophils isolated from healthy controls and individuals with AATD. Superoxide anion (O2−) production was determined from the rate of reduction of cytochrome c. Quantification of membrane NADPH-oxidase subunits was performed by mass spectrometry and western blot analysis. The clinical significance of our in vitro findings were assessed in patients with AATD and severe COPD receiving intravenous AAT replacement therapy. In vitro, AAT significantly inhibited O2− production by stimulated neutrophils and suppressed receptor stimulation of cyclic adenosimonophosphate (cAMP) and extracellular-signal regulated kinase (ERK)1/2 phosphorylation. In addition, AAT reduced plasma membrane translocation of cytosolic phox components of the NADPH-oxidase. Ex vivo, AATD neutrophils demonstrated increased plasma membrane associated p67phox and p47phox and significantly increased O2− production. The described variance in phox protein membrane assembly was resolved post AAT augmentation therapy in vivo, the effects of which significantly reduced AATD neutrophil O2− production to that of healthy control cells. These results expand our knowledge on the mechanism of neutrophil driven airways disease associated with AATD. Therapeutic AAT augmentation modified neutrophil NADPH-oxidase assembly and ROS production, with implications for clinical use in conditions in which oxidative stress plays a pathogenic role.

scholarly journals Endogenous pioneer neutrophils release NETs during the swarming response in zebrafish

2019 ◽  
Author(s):  
Hannah M. Isles ◽  
Catherine A. Loynes ◽  
Noémie Hamilton ◽  
Clare F. Muir ◽  
Anastasia Kadochnikova ◽  
...  
Keyword(s):  
Tissue Damage ◽  
Damage Model ◽  
Neutrophil Migration ◽  
Transgenic Zebrafish ◽  
Histone H2a ◽  
Zebrafish Model ◽  
Extracellular Traps ◽  
Sequence Of Events ◽  
Phase Sequence

AbstractNeutrophils are rapidly recruited to inflammatory sites where they coordinate their migration to form clusters, a process termed neutrophil swarming. The factors which modulate neutrophil swarming during its early stages are not fully understood, requiring the development of new in vivo models. Using transgenic zebrafish larvae to study endogenous neutrophil migration in a tissue damage model, we demonstrate that neutrophil swarming is a conserved process in zebrafish immunity, sharing essential features with mammalian systems. We show that neutrophil swarms initially develop around a pioneer neutrophil, in a three-phase sequence of events. By adopting a high-resolution confocal microscopy approach, we observed the release of cell fragments by early swarming neutrophils. We developed a neutrophil specific histone H2A transgenic reporter line TgBAC(mpx:GFP)i114;Tg(lyz:H2A-mCherry)sh530 to study neutrophil extracellular traps (NETs), and found that endogenous neutrophils recruited to sites of tissue damage released NETs at the start of the swarming process. The optical transparency achieved using the zebrafish model has provided some of the highest resolution imaging of NET release in vivo to date. Using a combination of transgenic reporter lines and DNA intercalating agents, we demonstrate that pioneer neutrophils release extracellular traps during the swarming response, suggesting that cell death signalling via NETosis might be important in driving the swarming response.

An ACE inhibitor reduces bactericidal activity of human neutrophils in vitro and impairs mouse neutrophil activity in vivo

2021 ◽  
Vol 13 (604) ◽  
pp. eabj2138
Author(s):  
Duo-Yao Cao ◽  
Jorge F. Giani ◽  
Luciana C. Veiras ◽  
Ellen A. Bernstein ◽  
Derick Okwan-Duodu ◽  
...  
Keyword(s):  
Bactericidal Activity ◽  
Angiotensin Converting Enzyme Inhibitors ◽  
Leukotriene B4 ◽  
Human Neutrophils ◽  
Converting Enzyme Inhibitors ◽  
Bacterial Killing ◽  
Increased Risk ◽  
The Impact

Angiotensin-converting enzyme inhibitors (ACEIs) are used by millions of patients to treat hypertension, diabetic kidney disease, and heart failure. However, these patients are often at increased risk of infection. To evaluate the impact of ACEIs on immune responses to infection, we compared the effect of an ACEI versus an angiotensin receptor blocker (ARB) on neutrophil antibacterial activity. ACEI exposure reduced the ability of murine neutrophils to kill methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, and Klebsiella pneumoniae in vitro. In vivo, ACEI-treated mice infected with MRSA had increased bacteremia and tissue bacteria counts compared to mice treated with an ARB or with no drug. Similarly, ACEIs, but not ARBs, increased the incidence of MRSA-induced infective endocarditis in mice with aortic valve injury. Neutrophils from ACE knockout (KO) mice or mice treated with an ACEI produced less leukotriene B4 (LTB4) upon stimulation with MRSA or lipopolysaccharide, whereas neutrophils overexpressing ACE produced more LTB4 compared to wild-type neutrophils. As a result of reduced LTB4 production, ACE KO neutrophils showed decreased survival signaling and increased apoptosis. In contrast, neutrophils overexpressing ACE had an enhanced survival phenotype. Last, in a cohort of human volunteers receiving the ACEI ramipril for 1 week, ACEI administration reduced neutrophil superoxide and reactive oxygen species production and neutrophils isolated from volunteers during ramipril treatment had reduced bactericidal activity. Together, these data demonstrate that ACEI treatment, but not ARB treatment, can reduce the bacterial killing ability of neutrophils.

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