Spontaneous formation of neutrophil extracellular traps in serum-free culture conditions.
Ontology highlight
ABSTRACT:
SUBMITTER: Kamoshida G
PROVIDER: S-EPMC5458474 | biostudies-literature | 2017 Jun
REPOSITORIES: biostudies-literature
Publications
Spontaneous formation of neutrophil extracellular traps in serum-free culture conditions.
Kamoshida Go G Kikuchi-Ueda Takane T Nishida Satoshi S Tansho-Nagakawa Shigeru S Kikuchi Hirotoshi H Ubagai Tsuneyuki T Ono Yasuo Y
FEBS open bio 20170502 6
Neutrophils play a critical role in the innate immune response. Recently, a new neutrophilic biological defense mechanism, termed neutrophil extracellular traps (NETs), has been attracting attention. Neutrophils have been observed to release both lysosomal enzymes and their nuclear contents, including unfolded chromatin, which together trap and inactivate bacteria. The environment in tissues where neutrophils act is thought to be different from that of the blood serum. In this study, we assessed ...[more]
Similar Datasets
Project description:Neutrophils release neutrophil extracellular traps (NETs), via NETosis, as a defense mechanism against pathogens. Neutrophils can release NETs spontaneously; however, the mechanisms underlying spontaneous NETosis remain unclear. Neutrophils isolated from healthy donors were tested for NET formation and autophagy at 1, 6, 12, and 24 h after incubation. Autophagy response was evaluated in response to various autophagy inducers and inhibitors. The relationship between autophagy and NETosis was detected in vivo using an ovalbumin-induced mouse model of asthma. We found that the increase in the proportion of spontaneous NETosis was time-dependent. The number of autophagy-positive cells also increased over time and LC3B protein played an integral role in NET formation. Trehalose (an inducer of mTOR-independent autophagy) treatment significantly increased NET formation, whereas rapamycin (an mTOR-dependent autophagy inducer) did not increase NET release by neutrophils. Compared with the control group, 3-methyladenine (an autophagy sequestration inhibitor) and hydroxychloroquine sulfate (autophagosome-lysosome fusion inhibitor) treatments significantly reduced the percentage of NET-positive cells. In vivo studies on ovalbumin-induced asthma lung sections revealed NETs and LC3B and citH3 proteins were found to co-localize with DNA. Our findings suggest that autophagy plays a crucial role in aging-related spontaneous NETosis.
| S-EPMC8671464 | biostudies-literature
Project description:The formation of neutrophil extracellular traps (NETs) is an immune defense mechanism of neutrophilic granulocytes. Moreover, it is also involved in the pathogenesis of autoimmune, inflammatory, and neoplastic diseases. For that reason, the process of NET formation (NETosis) is subject of intense ongoing research. In vitro approaches to quantify NET formation are commonly used and involve neutrophil stimulation with various activators such as phorbol 12-myristate 13-acetate (PMA), lipopolysaccharides (LPS), or calcium ionophores (CaI). However, the experimental conditions of these experiments, particularly the media and media supplements employed by different research groups, vary considerably, rendering comparisons of results difficult. Here, we present the first standardized investigation of the influence of different media supplements on NET formation in vitro. The addition of heat-inactivated (hi) fetal calf serum (FCS), 0.5% human serum albumin (HSA), or 0.5% bovine serum albumin (BSA) efficiently prevented NET formation of human neutrophils following stimulation with LPS and CaI, but not after stimulation with PMA. Thus, serum components such as HSA, BSA and hiFCS (at concentrations typically found in the literature) inhibit NET formation to different degrees, depending on the NETosis inducer used. In contrast, in murine neutrophils, NETosis was inhibited by FCS and BSA, regardless of the inducer employed. This shows that mouse and human neutrophils have different susceptibilities toward the inhibition of NETosis by albumin or serum components. Furthermore, we provide experimental evidence that albumin inhibits NETosis by scavenging activators such as LPS. We also put our results into the context of media supplements most commonly used in NET research. In experiments with human neutrophils, either FCS (0.5-10%), heat-inactivated (hiFCS, 0.1-10%) or human serum albumin (HSA, 0.05-2%) was commonly added to the medium. For murine neutrophils, serum-free medium was used in most cases for stimulation with LPS and CaI, reflecting the different sensitivities of human and murine neutrophils to media supplements. Thus, the choice of media supplements greatly determines the outcome of experiments on NET-formation, which must be taken into account in NETosis research.
| S-EPMC6354573 | biostudies-literature
Project description:Human mesenchymal stem cells (hMSCs) are widely used in clinical research because of their multipotential, immunomodulatory, and reparative properties. Previous studies determined that hMSC spheroids from a three-dimensional (3D) culture possess higher therapeutic efficacy than conventional hMSCs from a monolayer (2D) culture. To date, various 3D culture methods have been developed to form hMSC spheroids but most of them used culture medium containing fetal bovine serum (FBS), which is not suitable for further clinical use. Here, we demonstrate that dissociated single MSCs seeded in induced pluripotent stem medium (MiPS) adhere loosely to the dish and spontaneously migrate to form spheroids during day 3 to day 6. Through component deletion screening and complementation experiments, the knockout serum replacement (KSR) was identified as necessary and sufficient for hMSC spheroid formation. Transcriptome analysis showed that the overall expression profiles were highly similar between 2D culture with FBS and KSR-derived spheroids. Interestingly, genes related to inflammatory response, immune response, and angiogenesis were upregulated in spheroids at day 6 and qPCR results further validated the increased expression level of related genes, including STC1, CCL7, HGF, IL24, and TGFB3. When spheroids were replated in normal FBS medium, cells formed a typical spindle-shaped morphology and FACS results showed that the recovered cells retained MSC-specific surface markers, such as CD73, CD90, and CD105. In summary, we developed a practical and convenient method to generate hMSC spheroids for clinical research and therapy.
| S-EPMC6815607 | biostudies-literature
Project description:The inflammatory microenvironment is commonly characterized by extracellular acidosis (pH < 7.35). Sensitivity to pH, CO2 or bicarbonate concentrations allows neutrophils to react to changes in their environment and to detect inflamed areas in the tissue. One important antimicrobial effector mechanism is the production of neutrophil extracellular traps (NETs), which are released during a programmed reactive oxygen species (ROS)-dependent cell death, the so-called NETosis. Although several functions of neutrophils have been analyzed under acidic conditions, the effect of extracellular acidosis on NETosis remains mainly unexplored and the available experimental results are contradictory. We performed a comprehensive study with the aim to elucidate the effect of extracellular acidosis on ROS-dependent NETosis of primary human neutrophils and to identify the underlying mechanisms. The study was performed in parallel in a CO2-bicabonate-buffered culture medium, which mimics in vivo conditions, and under HEPES-buffered conditions to verify the effect of pH independent of CO2 or bicarbonate. We could clearly show that extracellular acidosis (pH 6.5, 6.0, and 5.5) and intracellular acidification inhibit the release of ROS-dependent NETs upon stimulation of neutrophils with phorbol myristate acetate and immobilized immune complexes. Moreover, our findings suggest that the diminished NET release is a consequence of reduced ROS production and diminished glycolysis of neutrophils under acidic conditions. It was suggested previously that neutrophils can sense the border of inflamed tissue by the pH gradient and that a drop in pH serves as an indicator for the progress of inflammation. Following this hypothesis, our data indicate that an acidic inflammatory environment results in inhibition of extracellular operating effector mechanisms of neutrophils such as release of ROS and NETs. This way the release of toxic components and tissue damage can be avoided. However, we observed that major antimicrobial effector mechanisms such as phagocytosis and the killing of pathogens by neutrophils remain functional under acidic conditions.
| S-EPMC5329032 | biostudies-literature
Project description:Neutrophil extracellular traps (NETs) contribute to inflammatory pathogenesis, especially in infectious and cardiovascular diseases. H2 gas acts as an antioxidant and has been clinically and experimentally proven to ameliorate inflammation. Therefore, we investigated whether H2 gas could inhibit NET formation associated with excessive neutrophil activation. Phorbol-12-myristate-13-acetate (PMA)-stimulated human neutrophils exposed to H2 exhibited reduced citrullination of histones, membrane disruption by chromatin complexes, and release of NET components over controls. Mechanistically, H2 suppressed the phosphorylation of Ser-139 residue in H2AX, a marker of DNA damage, thereby reducing the expression of CXC-chemokine receptor 4 (CXCR4) in PMA-stimulated neutrophils. Along with the upregulation of CXCR4, the intracellular content of myeloperoxidase (MPO) and the production of MPO-derived hypochlorous acid (HOCl) was increased; however, these effects were markedly suppressed in H2-exposed cultures. Thus, H2 neutralized HOCl produced by the oxidative burst, inhibited DNA damage, and subsequently inhibited NET formation. We further confirmed that inhalation of H2 inhibited the formation and release of NET components in the blood and bronchoalveolar lavage of a lipopolysaccharide-induced sepsis model in mice and aged minipigs. Therefore, H2 therapy has the potential to be a new therapeutic agent for inflammatory diseases involving NETs associated with excessive neutrophil activation.
2022-02-23 | GSE178883 | GEO
Project description:Nontypeable Haemophilus influenzae (NTHI) is a leading cause of otitis media infections, which are often chronic and/or recurrent in nature. NTHI and other bacterial species persist in vivo within biofilms during otitis media and other persistent infections. These biofilms have a significant host component that includes neutrophil extracellular traps (NETs). These NETs do not mediate clearance of NTHI, which survives within NET structures by means of specific subpopulations of lipooligosaccharides on the bacterial surface that are determinants of biofilm formation in vitro. In this study, the ability of NTHI and NTHI components to initiate NET formation was examined using an in vitro model system. Both viable and nonviable NTHI strains were shown to promote NET formation, as did preparations of bacterial DNA, outer membrane proteins, and lipooligosaccharide (endotoxin). However, only endotoxin from a parental strain of NTHI exhibited equivalent potency in NET formation to that of NTHI. Additional studies showed that NTHI entrapped within NET structures is resistant to both extracellular killing within NETs and phagocytic killing by incoming neutrophils, due to oligosaccharide moieties within the lipooligosaccharides. Thus, we concluded that NTHI elicits NET formation by means of multiple pathogen-associated molecular patterns (most notably endotoxin) and is highly resistant to killing within NET structures. These data support the conclusion that, for NTHI, formation of NET structures may be a persistence determinant by providing a niche within the middle-ear chamber.
| S-EPMC3019868 | biostudies-other
Project description:Accumulating data suggest that neutrophil extracellular traps (NETs) exert a key function in several diseases. Peptidylarginine deiminase 4 (PAD4) regulates NET formation via citrullination of histones. The aim of this study was to examine the role of miR-155 in controlling PAD4-dependent generation of NETs. Bone marrow neutrophils were stimulated with PMA and MIP-2. Pre-incubation of neutrophils with translational inhibitors (cycloheximide or puromycin) markedly decreased NET formation induced by PMA or MIP-2. Neutrophil transfection with a mimic miR-155 increased PMA-induced PAD4 mRNA expression and NET formation. In contrast, transfection with an antagomiR-155 decreased induction of PAD4 mRNA and NETs in response to PMA challenge. Bioinformatical examination of PAD4 revealed a potential binding site in AU-rich elements at the 3'-UTR region. MiR-155 binding to PAD4 was examined by use of target site blockers and RNA immunoprecipitation, revealing that miR-155 regulation of PAD4 mRNA is mediated via AU-rich elements in the 3'-UTR region. In conclusion, our findings demonstrate that miR-155 positively regulates neutrophil expression of PAD4 and expulsion of extracellular traps. Thus, our novel results indicate that targeting miR-155 might be useful to inhibit exaggerated NET generation in inflammatory diseases.
| S-EPMC6838784 | biostudies-literature
Project description:Low back pain following spine surgery is a major complication due to excessive epidural fibrosis, which compresses the lumbar nerve. The mechanisms of epidural fibrosis remain largely elusive. In the drainage samples from patients after spine operation, neutrophil extracellular traps (NETs) and NETs inducer high-mobility group box 1 were significantly increased. In a mouse model of laminectomy, NETs developed in the wound area post epidural operation, accompanied with macrophage infiltration. In vitro, macrophages ingested NETs and thereby increased the elastase from NETs via the receptor for advanced glycation end product. Moreover, NETs boosted the expression of fibronectin in macrophages, which was dependent on elastase and could be partially blocked by DNase. NF-κB p65 and Smad pathways contributed to the increased expression fibronectin in NETs-treated macrophages. In the mouse spine operation model, post-epidural fibrosis was significantly mitigated with the administration of DNase I, which degraded DNA and cleaved NETs. Our study shed light on the roles and mechanisms of NETs in the scar formation post spine operation.
| S-EPMC7599244 | biostudies-literature
Project description:Neutrophil extracellular traps (NETs) are one of the most powerful and specific tools for neutrophils to clean up extracellular microbes, but the mechanisms of NETosis under infection are scarcely studied. In this study, by examining the neutrophils from human peripheral blood and mouse abdomen, we demonstrated that PRAK dysfunction resulted in a significantly reduced NET formation and elevated apoptotic cells. Furthermore, PRAK dysfunction could lead to impaired NET-mediated antibacterial activity and shorten the survival of mice with CLP-induced sepsis. Mechanism studies revealed that attenuated NET formation in PRAK dysfunctional neutrophils correlated with overproduction of reactive oxygen species (ROS), which triggered apoptosis through excessive autophagy. The imbalance of NET formation and apoptosis was further regulated by treatment with lower ROS in hypoxia. Here, we propose a novel candidate, PRAK, which can sense the oxidative stress and regulate the releasing of ROS, may be the master molecular switch to regulate the NETosis-apoptosis axis of neutrophils.
| S-EPMC6559312 | biostudies-literature
Project description:Staphylococcus aureus secretes numerous virulence factors that facilitate evasion of the host immune system. Among these molecules are pore-forming cytolytic toxins, including Panton-Valentine leukocidin (PVL), leukotoxin GH (LukGH; also known as LukAB), leukotoxin DE, and γ-hemolysin. PVL and LukGH have potent cytolytic activity in vitro, and both toxins are proinflammatory in vivo. Although progress has been made toward elucidating the role of these toxins in S. aureus virulence, our understanding of the mechanisms that underlie the proinflammatory capacity of these toxins, as well as the associated host response toward them, is incomplete. To address this deficiency in knowledge, we assessed the ability of LukGH to prime human PMNs for enhanced bactericidal activity and further investigated the impact of the toxin on neutrophil function. We found that, unlike PVL, LukGH did not prime human neutrophils for increased production of reactive oxygen species nor did it enhance binding and/or uptake of S. aureus. Unexpectedly, LukGH promoted the release of neutrophil extracellular traps (NETs), which, in turn, ensnared but did not kill S. aureus. Furthermore, we found that electropermeabilization of human neutrophils, used as a separate means to create pores in the neutrophil plasma membrane, similarly induced formation of NETs, a finding consistent with the notion that NETs can form during nonspecific cytolysis. We propose that the ability of LukGH to promote formation of NETs contributes to the inflammatory response and host defense against S. aureus infection.
| S-EPMC3903389 | biostudies-literature