Objective To evaluate the correlation between alterations in DNase1 and DNase1L3 enzyme activities and impairment of NET degradation in patients with sporadic SLE, and to investigate the underlying mechanism. Methods 46 sporadic SLE patients and 30 age- and sex-matched healthy individuals were recruited. Serum levels of DNase1, DNase1L3 and corresponding autoantibodies were detected by ELISA. DNase1 and DNase1L3 were isolated by immunoprecipitation; NETs and enzyme degradation activities were detected using a modified immunofluorescence. DNase1L3 secretion by PBMCs was analyzed by ELISPOT, Western blotting and reverse transcription PCR. Results Levels of H3-dsDNA and Ela-dsDNA complexes were significantly elevated in SLE patients. LDGs in SLE population was significantly higher than in the control group, and LDGs was positively correlated with H3-dsDNA and Ela-dsDNA NETs complexes. The ability of SLE patients to degrade NET in vitro was significantly lower than that of the control group. Degradation experiments of DNase1 and DNase1L3 in different proportions showed that the decrease in DNase1L3 activity was the primary contributor to the elevated NET residue level. The concentration of DNase1L3 autoantibodies in SLE patients was significantly elevated compared to the control group. In addition, the capacity of PBMCs to secrete DNase1L3 was significantly lower in the SLE patients compared to the control group. Conclusion Decreased secretion of DNase1L3 and the presence of relevant autoantibodies notably impede NET degradation in patients with SLE, offering new directions for the monitoring and treatment of SLE patients.
Humans ; Autoantibodies ; Blotting, Western ; Enzyme-Linked Immunosorbent Assay ; Extracellular Traps ; Lupus Erythematosus, Systemic

OBJECTIVES: To investigate the clinical value of complement-3a receptor 1 (C3aR1) and neutrophil extracellular traps (NETs) in predicting sepsis-induced coagulopathy (SIC). METHODS: A prospective study was conducted among 78 children with sepsis who attended Xuzhou Children's Hospital Affiliated to Xuzhou Medical University from June 2022 to June 2023. According to the presence or absence of SIC, they were divided into two groups: SIC (n=36) and non-SIC (n=42) . The two groups were compared in terms of clinical data and the levels of C3aR1 and NETs. The factors associated with the occurrence of SIC were analyzed. The receiver operating characteristic (ROC) curve was used to evaluate the performance of C3aR1 and NETs in predicting SIC. RESULTS: Compared with the non-SIC group, the SIC group had significantly higher levels of C-reactive protein, interleukin-6 (IL-6), interleukin-10, C3aR1, and NETs (P<0.05). The multivaiate logistic regression analysis showed that the increases in C3aR1, NETs, and IL-6 were closely associated with the occurrence of SIC (P<0.05). The ROC curve analysis showed that C3aR1 combined with NETs had an area under the curve (AUC) of 0.913 in predicting SIC (P<0.05), which was significantly higher than the AUC of C3aR1 or IL-6 (P<0.05), while there was no significant difference in AUC between C3aR1 combined with NETs and NETs alone (P>0.05). CONCLUSIONS There are significant increases in the expression levels of C3aR1 and NETs in the peripheral blood of children with SIC, and the expression levels of C3aR1 and NETs have a high clinical value in predicting SIC.
Child ; Humans ; Extracellular Traps ; Interleukin-6 ; Prospective Studies ; Sepsis/complications* ; C-Reactive Protein ; Blood Coagulation Disorders ; ROC Curve ; Prognosis

OBJECTIVE: To investigate the causal relationship between neutrophil extracellular trap (NET) and sepsis based on Mendelian randomization analysis. METHODS: The genome wide association study (GWAS) dataset for the NET biomarker myeloperoxidase (MPO)-DNA complex based on Donkel et al. 's Rotterdam study (RS) and GWAS dataset for identifying sepsis from the UK biobank were selected to screen single nucleotide polymorphisms (SNPS) associated with MPO-DNA complex as instrumental variable (IV) for genetic variation, using MPO-DNA complex as exposure factor. Potential causal associations between MPO-DNA complex and the risk of occurrence of sepsis, 28-day death from sepsis, need for intensive care due to sepsis, and 28-day death from sepsis requiring intensive care were analyzed using a two-sample, one-way Mendelian randomization analysis primary analysis method of inverse analysis of variance (IVW). Potential pleiotropy was assessed using the MR Egger regression intercept test. Sensitivity analysis was performed using the "leave one out" test. RESULTS: The GWAS data were obtained from a European population of both sexes, and the screening criteria was based on the three main assumptions of Mendelian randomization, resulting in 22 SNP entering the Mendelian randomization analysis. The results of the Mendelian randomization causal association effect analysis using the IVW method showed that for every standard deviation increase in the level of the MPO-DNA complex, the risk of sepsis increased by approximately 18% [odds ratio (OR) = 1.18, 95% confidence interval (95%CI) was 1.07-1.29, P < 0.001], the risk of 28-day death from sepsis increased by approximately 51% (OR = 1.51, 95%CI was 1.27-1.81, P < 0.001), an increase of approximately 38% in the risk of occurrence of needing intensive care due to sepsis (OR = 1.38, 95%CI was 1.12-1.70, P = 0.002), and an increase of approximately 125% in the risk of 28-day death from sepsis requiring intensive care (OR = 2.25, 95%CI was 1.21-4.18, P = 0.01). MR Egger regression intercept test suggested that there was no horizontal pleiotropy in the included SNP, and the MR-PRESSO test did not find outliers. Sensitivity analysis suggested that the results of Mendelian randomization were robust. CONCLUSIONS Rising NET can increase the risk of sepsis onset, progression and death as derived from Mendelian randomization analysis.
Female ; Male ; Humans ; Extracellular Traps ; Genome-Wide Association Study ; Mendelian Randomization Analysis ; Sepsis/genetics* ; Nonoxynol ; DNA

Objective To explore the role of autophagy, apoptosis of neutrophils and neutrophils extracellular traps (NET) formation in systemic lupus erythematosus (SLE). Methods Thirty-six patients with SLE were recruited as research subjects, and 32 healthy controls matched accordingly were enrolled as control subjects. The expression levels of microtubule associated protein 1 light chain 3B (LC3B), autophagy-related gene5(ATG5), P62, B-cell lymphoma 2(Bcl2), Bcl2-related X protein (BAX) in neutrophils were detected by Western blot analysis. Flow cytometry was employed to analyze the expression of LC3B on neutrophils. The expression level of myeloperoxidase(MPO) in plasma was estimated by ELISA. Furthermore, neutrophils were cultured in vitro and stimulated by 100 nmol/L rapamycin and 10 μg/mL lipopolysaccharide (LPS) for 6 hours, respectively. And then, the expression levels of LC3B, ATG5, P62, Bcl2 and BAX in neutrophils were detected by Western blot analysis. The level of MPO in culture supernatant was detected by ELISA. The change of fluorescence intensity of NET in culture supernatant was assayed by Sytox^TM Green staining combined with fluorescence spectrophotometry. Results Compared with healthy controls, the levels of autophagy and apoptosis of neutrophils and NET formation in SLE patients were increased. The level of apoptosis and NET formation was positively associated with neutrophil autophagy. The level of autophagy showed an increase but had no effect on apoptosis and NET formation for neutrophil stimulated by rapamycin. The levels of autophagy and NET formation also increased with no significant effect on apoptosis for neutrophil induced by LPS. Conclusion The autophagy, apoptosis and NET formation of neutrophils increase in SLE patients. The activation of autophagy and NET in neutrophils possibly result from the inflammatory internal environment in SLE patients.
Humans ; Neutrophils ; Extracellular Traps/metabolism* ; Lipopolysaccharides/pharmacology* ; bcl-2-Associated X Protein/metabolism* ; Sirolimus/pharmacology* ; Lupus Erythematosus, Systemic ; Autophagy

Neutrophils play an important role in infectious diseases by clearing pathogens in the early stages of the disease and damaging the surrounding tissues along with the disease progress. Low-density neutrophils (LDNs) are a crucial and distinct subpopulation of neutrophils. They are a mixture of activated and degranulated normal mature neutrophils and a considerable number of immature neutrophils prematurely released from the bone marrow. Additionally, they may be involved in the occurrence and development of diseases through the changes in phagocytosis, the generation of reactive oxygen species (ROS), the enhancement of the ability to produce neutrophils extracellular traps and immunosuppression. We summarizes the role of LDNs in the pathogenesis and their correlation with the severity of infectious diseases such as COVID-19, severe fever with thrombocytopenia syndrome (SFTS), AIDS, and tuberculosis.
Humans ; Neutrophils ; COVID-19/pathology* ; Phagocytosis ; Extracellular Traps ; Communicable Diseases ; Reactive Oxygen Species

Objective To investigate how the neutrophil extracellular traps (NETs) affect the proliferation and migration of mouse MC38 colorectal cancer cells and its mechanism. Methods Spleen neutrophils were extracted in mouse, followed by collection of NETs after ionomycin stimulation in vitro. The proliferation of MC38 cell was detected by CCK-8 assay, and migration ability were detected by Transwell^TM and cell scratch assay, after co-incubation with MC38 cells. The mRNA expression of cellular matrix metalloproteinase 2 (MMP2) and MMP9 were detected by real-time fluorescence quantitative PCR, and the expression of MMP2, MMP9 and focal adhesion kinase (FAK), phosphorylated FAK protein were detected by Western blot. After silencing MMP9 using small interfering RNA (siRNA), the effect of NETs on the proliferation and migration ability of MC38 cells and the altered expression of related molecules were examined by previous approach. Results NETs promoted the proliferation and migration of MC38 cells and up-regulated the MMP9 expression and FAK phosphorylation. Silencing MMP9 inhibited the promotion of MC38 proliferation and migration by NETs and suppressed FAK phosphorylation. Conclusion NETs up-regulates MMP9 expression in MC38 cells, activates FAK signaling pathway and promotes tumor cell proliferation and migration.
Animals ; Mice ; Focal Adhesion Protein-Tyrosine Kinases/metabolism* ; Matrix Metalloproteinase 2/metabolism* ; Matrix Metalloproteinase 9/metabolism* ; Extracellular Traps/metabolism* ; Cell Movement ; Cell Proliferation ; RNA, Small Interfering/genetics* ; Colorectal Neoplasms/genetics* ; Cell Line, Tumor

OBJECTIVES: To study the changes in cell free-DNA (cf-DNA), a marker of neutrophil extracellular traps (NETs), in neonates with acute respiratory distress syndrome (ARDS), and to evaluate its relationship with the severity and early diagnosis of ARDS. METHODS: The neonates diagnosed with ARDS in the Affiliated Hospital of Jiangsu University from January 2021 to June 2022 were enrolled in the prospective study. The neonates were divided into mild, moderate, and severe ARDS groups based on the oxygen index (OI) (4≤OI<8, 8≤OI<16, and OI≥16, respectively). The control group was selected from jaundice neonates who were observed in the neonatal department of the hospital during the same period, and they had no pathological factors causing neonatal jaundice. Peripheral blood samples were collected on day 1, day 3, and day 7 after admission for the ARDS group, and on the day of admission for the control group. Serum cf-DNA levels were measured using a fluorescence enzyme-linked immunosorbent assay. Serum interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) levels were measured using enzyme-linked immunosorbent assay. A Pearson correlation analysis was used to evaluate the correlation of serum cf-DNA levels with serum IL-6 and TNF-α levels. RESULTS: A total of 50 neonates were enrolled in the ARDS group, including 15 neonates with mild ARDS, 25 with moderate ARDS, and 10 with severe ARDS. Twenty-five neonates were enrolled in the control group. Compared with the control group, the serum levels of cf-DNA, IL-6, and TNF-α in all ARDS groups were significantly increased (P<0.05). Compared with the mild ARDS group, the serum levels of cf-DNA, IL-6, and TNF-α in the moderate and severe ARDS groups were significantly increased (P<0.05), and the increase was more significant in the severe ARDS group (P<0.05). The serum levels of cf-DNA, IL-6, and TNF-α in all ARDS groups were significantly increased on day 3 after admission and significantly decreased on day 7 after admission compared with those on day 1 after admission (P<0.05). The Pearson correlation analysis showed that there was a positive correlation between serum cf-DNA levels and IL-6 levels as well as TNF-α levels in 50 neonates with ARDS (P<0.05). CONCLUSIONS There is an excessive expression of NETs in neonates with ARDS, and dynamic monitoring of serum cf-DNA levels has certain clinical value in evaluating the severity and early diagnosis of ARDS in neonates.
Infant, Newborn ; Humans ; Extracellular Traps ; Prospective Studies ; Tumor Necrosis Factor-alpha ; Interleukin-6 ; Prognosis ; ROC Curve ; Respiratory Distress Syndrome ; DNA

OBJECTIVE: To investigate the mechanisms underlying allergic conjunctivitis caused by conjunctival epithelial cell damage, neutrophil migration and neutrophil extracellular traps (NETs) formation induced by crude extracts of Dermatophagoides farinae mite (CDM). METHODS: Human conjunctival epithelial cells were stimulated with 500, 1 000, 2 000, 4 000 ng/mL, and the expression levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ) and IL-8 were detected using quantitative real-time PCR (qPCR) assay and enzyme-linked immunosorbent assay (ELISA). The culture supernatant of human conjunctival epithelial cells was collected and co-cultured with neutrophils. Neutrophil migration was measured using Transwell migration assay, and the expression of NETs markers myeloperoxidase (MPO) and citrullinated histone H3 (CitH3) was quantified using immunofluorescence staining. Neutrophils were stimulated with phorbol 12-myristate 13-acetate (PMA), and then NETs were collected for treatment of human conjunctival epithelial cells. Cell apoptosis was detected using flow cytometry, and the levels of IL-6, TNF-α, IFN-γ and IL-8 were measured in the cell culture supernatant using ELISA. RESULTS: Treatment with CDM at concentrations of 2 000 ng/mL and 4 000 ng/mL up-regulated IL-6, TNF-α, IFN-γ and IL-8 expression in human conjunctival epithelial cells. Following treatment with CDM at concentrations of 2 000 ng/mL and 4 000 ng/mL, the culture supernatant of human conjunctival epithelial cells promoted neutrophil migration and induced increases in the staining intensity of MPO and CitH3. In addition, increased NETs triggered the apoptosis of human conjunctival epithelial cells and IL-6, TNF-α, IFN-γ and IL-8 secretion in the culture supernatant of human conjunctival epithelial cells. CONCLUSIONS CDM induces human conjunctival epithelial cell damages, thereby promoting neutrophil migration and NETs formation, while the release of NETs further aggravates human conjunctival epithelial cell damages.
Animals ; Humans ; Extracellular Traps ; Neutrophils ; Interleukin-8/metabolism* ; Dermatophagoides farinae ; Interleukin-6/metabolism* ; Tumor Necrosis Factor-alpha/metabolism* ; Epithelial Cells ; Interferon-gamma/metabolism* ; Tetradecanoylphorbol Acetate/pharmacology*

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

Extracellular traps released by neutrophils (neutrophil extracellular traps, NETs) are a double-edged sword, and understanding the mechanism of NET formation is of great significance for disease treatment. However, the short lifespan, the large individual differences, and the inability to perform gene editing render it difficult to decipher NET formation using neutrophils. It is necessary to find a model cell to replace neutrophils to study the mechanism of NET formation. In this study, we used different concentrations (0, 0.1, 1, and 10 μmol/L) of all-trans retinoic acid (ATRA) to differentiate HL-60 cells for different days (1, 3, 5, and 7 days). By detecting the cell viability and nuclear morphology of cells, we confirmed that HL-60 cells were differentiated to neutrophil-like cells (dHL-60) after treated with ATRA for at least 5 days. Using immunofluorescence staining to detect the formation of NETs, we demonstrated that dHL-60 cells differentiated for 5 days with 1 μmol/L ATRA could generate NETs comparable to those produced by neutrophils upon phorbol 12-myristate 13-acetate (PMA) stimulation, without histone H3 citrullination. Furthermore, the formation of NETs by dHL-60 cells were NADPH-dependent and PAD4-independent, consistent with neutrophils. Taken together, these observations suggest that dHL-60 cells differentiated with 1 μmol/L ATRA for 5 days can be used as a model cell for neutrophils to study the mechanism of NET formation.
Humans ; Extracellular Traps ; Tetradecanoylphorbol Acetate/pharmacology* ; Neutrophils ; HL-60 Cells ; Tretinoin/pharmacology*