No abstract available.
Extracellular Traps* ; Neutrophils*

Autoimmune Diseases ; Extracellular Traps ; Humans ; Neutrophils

Neutrophil extracellular traps (NETs) represent a form of cell death distinct from apoptosis or necrosis. The imbalance between the formation and degradation of NETs has long been considered to be closely associated with the activity of autoimmune diseases such as systemic lupus erythematous (SLE). Reactive oxygen species derived from the nicotinamide adenine dinucleotide phosphate oxidase pathway or mitochondrial DNA pathway play a key role in the primary stage of NETs formation. The exposure or delayed degradation of abundant autoantigens, such as double-strand DNA, caused by abnormal activation of neutrophils can induce autoantibody to form immune complexes that deposit in local tissues and then induce the plasmacytoid dendritic cells to secrete the interferon alpha and other inflammatory factors. Those inflammatory factors will eventually cause endothelial cell injury. In order to provide a theoretical basis for targeted therapy and diagnosis of childhood-onset SLE, this paper reviews the role of NETs in the pathogenesis of SLE.
Extracellular Traps ; Humans ; Lupus Erythematosus, Systemic ; etiology ; therapy ; Neutrophils ; physiology

Autophagy is a highly conserved intracellular degradation and energy-recycling mechanism that contributes to the maintenance of cellular homeostasis. Extensive researches over the past decades have defined the role of autophagy innate immune cells. In this review, we describe the current state of knowledge regarding the role of autophagy in neutrophil biology and a picture of molecular mechanism underlying autophagy in neutrophils. Neutrophils are professional phagocytes that comprise the first line of defense against pathogen. Autophagy machineries are highly conserved in neutrophils. Autophagy is not only involved in generalized function of neutrophils such as differentiation in bone marrow but also plays crucial role effector functions of neutrophils such as granule formation, degranulation, neutrophil extracellular traps release, cytokine production, bactericidal activity and controlling inflammation. This review outlines the current understanding of autophagy in neutrophils and provides insight towards identification of novel therapeutics targeting autophagy in neutrophils.
Autophagy ; Biology ; Bone Marrow ; Extracellular Traps ; Homeostasis ; Inflammation ; Neutrophils ; Phagocytes

Neutrophil extracellular traps(NET)is neutrophil-derived extracellular fiber web-like structure, composed of DNA scaffold studded with various active proteins. In addition to its bactericidal effect, NET is closely related to various diseases including immune disease, thrombosis and tumor. Recently, lots of researches have shown that NET is highly expressed in a variety of tumors, tumor cells and microenvironment can promote NET formation, whereas NET participates in tumor progression as well, and is closely related to tumor proliferation, metastasis and thrombosis, which provides new clinical thinking in tumor diagnosis as well as treatment indeed. This review will focus on the research progress of NET and tumor, meanwhile make a prospect for its clinical application value.
Extracellular Traps ; genetics ; Humans ; Neoplasms ; physiopathology ; Neutrophils ; pathology ; Tumor Microenvironment

Neutrophils are professional phagocytes that conduct effectors functions in the innate immune systems. They are differentiated in the bone marrow (BM) and terminally differentiated neutrophils are then released into systemic circulation. Neutrophils migrate into inflammatory foci through extravasation, reverse transmigration, and chemotaxis. As neutrophils arrive at a target site, they actively participate in eliminating pathogens. They phagocytose bacteria, and eliminate them through the generation of reactive oxygen species (ROS), release of protease-enriched granules, and formation of neutrophil extracellular traps (NETs). Since neutrophils are equipped with toxic arsenals, the activation of neutrophils is tightly controlled. Priming is the process of unlocking safety mechanisms before complete activation of neutrophils. Since the first discovery of neutrophils, they were considered as a homogeneous population with an inflammatory phenotype. However, heterogenous populations of neutrophils were discovered under physiological and pathological conditions. This review outlines the normal differentiation of neutrophils in the BM, and discusses the current understandings of neutrophil heterogeneity.
Bacteria ; Bone Marrow ; Chemotaxis ; Extracellular Traps ; Immune System ; Neutrophils* ; Phagocytes ; Phenotype ; Population Characteristics* ; Reactive Oxygen Species

OBJECTIVETo explore the effects of exogenous carbon monoxide-releasing molecule 2 (CORM-2) on formation of human neutrophil extracellular traps (NETs) stimulated by endotoxin/lipopolysaccharide (LPS) and its relevant mechanism.

METHODSVenous blood samples were collected from a healthy adult volunteer to isolate neutrophils. The neutrophils were divided into normal control (NC) group, LPS group, LPS+ 10 μmol/L CORM-2 group, LPS+ 50 μmol/L CORM-2 group, and LPS+ inactive CORM-2 (iCORM-2) group according to the random number table. No treatment was given to the neutrophils in NC group. The neutrophils in LPS group underwent LPS stimulation (1 μL, 1 μg/mL). The neutrophils in LPS+ 10 μmol/L CORM-2 group, LPS+ 50 μmol/L CORM-2 group, and LPS+ iCORM-2 group underwent the same LPS stimulation as that in LPS group and treatment of 10 μmol/L CORM-2, 50 μmol/L CORM-2, and 50 μmol/L iCORM-2, respectively, with the volune of 1 μL. After conventional culture for 1 h, the number of NETs was determined with propidium iodide staining method; the early cell apoptosis rate was determined with flow cytometer; the generation level of reactive oxygen species (ROS) was assessed with dihydrogenrhodamine 123 fluorescent probe staining method (denoted as mean fluorescence intensity); the expression level of phosphorylated extracellular regulated kinase 1/2 (p-ERK1/2) was determined by Western blotting. The sample numbers of each group in the 4 experiments were all 5. Data were processed with one-way analysis of variance and SNK test.

RESULTS(1) The numbers of NETs per 400-time visual field in cells of LPS and LPS+ iCORM-2 groups were close to the number in NC group (with P values above 0.05). The number of NETs per 400-time visual field was significantly larger in cells of LPS+ 10 μmol/L CORM-2 and LPS+ 50 μmol/L CORM-2 groups than in NC and LPS groups (with P values below 0.05). The number of NETs per 400-time visual field in cells of LPS+ iCORM-2 group was close to that of LPS group (P>0.05). (2) The early cell apoptosis rate was significantly increased in LPS, LPS+ 10 μmol/L CORM-2, LPS+ 50 μmol/L CORM-2, and LPS+ iCORM-2 groups than in NC group (with P values below 0.05). The early cell apoptosis rates in LPS+ 10 μmol/L CORM-2, LPS+ 50 μmol/L CORM-2, and LPS+ iCORM-2 groups were close to the rate in LPS group (with P values above 0.05). (3) The generation level of ROS was significantly higher in cells of LPS, LPS+ 10 μmol/L CORM-2, and LPS+ iCORM-2 groups than in NC group (with P values below 0.05). The generation level of ROS in cells of LPS+ 50 μmol/L CORM-2 group was close to that of NC group (P>0.05). The generation level of ROS was lower in cells of LPS+ 10 μmol/L CORM-2 and LPS+ 50 μmol/L CORM-2 groups than in LPS group (with P values below 0.05), while the generation level of ROS in cells of LPS+ iCORM-2 group was close to that of LPS group (P>0.05). (4) The expression levels of p-ERK1/2 in cells of LPS and LPS+ iCORM-2 groups (respectively 0.0311±0.001 and 0.0309±0.0018) were close to the level in NC group (0.0304±0.0046, with P values above 0.05). The expression level of p-ERK1/2 was significantly higher in cells of LPS+ 10 μmol/L CORM-2 and LPS+ 50 μmol/L CORM-2 groups (respectively 0.7891±0.0201 and 1.2970±0.0056) than in NC group (with P values below 0.05). The expression level of p-ERK1/2 was significantly higher in cells of LPS+ 10 μmol/L CORM-2 and LPS+ 50 μmol/L CORM-2 groups than in LPS group (with P values below 0.05). The expression level of p-ERK1/2 in cells of LPS+ iCORM-2 group was close to that of LPS group (P>0.05).

CONCLUSIONSCORM-2 can obviously increase the production of NETs in LPS-induced neutrophils, and it might be attributable to the promotion of inhibition of ROS generation and phosphorylation of ERK1/2.

Apoptosis ; Carbon Monoxide ; metabolism ; Extracellular Traps ; Humans ; Lipopolysaccharides ; pharmacology ; Organometallic Compounds ; pharmacology ; Phosphorylation ; drug effects

Neutrophil extracellular traps(NETs) are networks of extracellular fibers primarily composed of DNA, histones, granular proteins, and cytoplasmic proteins and released to the outside of cells by neutrophils under the stimulation of bacteria, fungi, viruses, parasites, etc. NETs are generated in two forms, suicidal NETs and vital NETs, according to different stimuli. NETs have both anti-inflammatory and pro-inflammatory effects. On the one hand, they can play the anti-microbial role to resist inflammation by capturing, fixing, and killing invading pathogens, which is a special way for neutrophils to exert host defenses. On the other hand, in case of excessive formation or insufficient elimination, they can cause tissue damage directly, and also promote the release of inflammatory factors by recruiting other pro-inflammatory cells or proteins to further expand the inflammatory response, which is related to the pathologies of many diseases. In autoimmune diseases, NETs as important sources of autoantigens, can act as danger-associated molecular patterns( DAMPs) and activate the nucleotide-binding oligomerization domain leucine-rich repeats containing pyrin domain 3(NLRP3) inflammasome and complement system, thereby breaking self-tolerance and accelerating autoimmune inflammation. In addition, NETs can also activate other immune cells(such as B cells, antigen-presenting cells, and T cells) and regulate the acquired immune response. The present study reviewed the correlation of NETs with diseases such as systemic lupus erythematosus(SLE), rheumatoid arthritis(RA), and gouty arthritis(GA) to reveal the effect of dynamic balance between formation and clearance of NETs in autoimmune diseases and provide a theoretical basis for the investigation of underlying mechanisms and targeted therapies of traditional Chinese medicine.
Arthritis, Rheumatoid ; Autoimmune Diseases ; Extracellular Traps ; Humans ; Lupus Erythematosus, Systemic ; Neutrophils

Neutrophil extracellular traps (NETs) play an important role in the formation of immunothrombosis. However, how vascular endothelial cells mediate the formation of NETs has not been fully understood. We stimulated neutrophils firmly attached on the endothelial cell surface intercellular adhesion molecule-1 (ICAM-1) with lipopolysaccharide (LPS) or phorbol-12-myristate-13-acetate (PMA) for 4 h, then labeled NETs-DNA with Sytox green dye and the formation of NETs was observed by fluorescent microscopy. The area and fluorescence intensity of NETs-DNA were analyzed to quantify the formation of NETs. The results showed that both PMA and LPS were able to induce firmly adhered neutrophils on ICAM-1 to produce NETs. NETs induced by PMA were independent of neither β2 integrin lymphocyte function-associated antigen-1 (LFA-1) nor macrophage antigen complex-1 (Mac-1). In contrast, LPS-stimulated NETs were mediated by Mac-1 integrin, but not by LFA-1. After inhibition of actin filaments or Talin-1, the formation of NETs irrespective of the stimulus was significantly reduced. This study reveals the mechanism of the direct interaction between neutrophils and endothelial cells to produce NETs under inflammatory conditions, providing a new theoretical basis for the treatment of related diseases and the development of new drugs.
Cytoskeletal Proteins ; Endothelial Cells ; Extracellular Traps ; Integrins ; Intercellular Adhesion Molecule-1 ; Lipopolysaccharides/pharmacology* ; Macrophages ; Neutrophils

Neutrophils are predominant leukocytes in the circulation, which are essential for killing invading pathogens via the activation of effector responses and the production of reactive oxygen species (ROS), also named as "oxidative burst." When infected, activated neutrophils fight bacteria, fungi, and viruses through oxidative burst, phagocytosis, degranulation, and the production of neutrophil extracellular traps (NETs) in a neutrophil death process named as "NETosis" (Mutua and Gershwin, 2021). NETs, consisting of DNA fibers decorated with modified histones and numerous antimicrobial proteins from cytoplasmic granules and the nucleus, can either be beneficial or detrimental (Mutua and Gershwin, 2021). Several pathways can lead to this death process. In response to various stimuli, NETosis traps and clears pathogens, facilitating phagocytosis by other neutrophils and phagocytes. However, excessive NETosis often results in disease due to increasing the pro-inflammatory response and perpetuating the inflammatory condition (Hellebrekers et al., 2018; Hidalgo et al., 2019; Klopf et al., 2021). Accordingly, inhibiting aberrant NETosis may alleviate the severity of various autoimmune and inflammatory diseases.
DNA ; Extracellular Traps/metabolism* ; Neutrophils/metabolism* ; Reactive Oxygen Species/metabolism* ; Respiratory Burst