Neutrophil extracellular traps mediate neuro-immunothrombosis

Neutrophil extracellular traps are primarily composed of DNA and histones and are released by neutrophils to promote inflammation and thrombosis when stimulated by various inflammato ry reactions.Neutrophil extracellular trap formation occurs through lytic and non-lytic pathways that can be further classified by formation mechanisms.Histones,von Willebrand factor,fibrin,and many other factors participate in the interplay between inflammation and thrombosis.Neuroimmunothrombosis summarizes the intricate interplay between inflammation and thrombosis during neural development and the pathogenesis of neurological diseases,providing cutting-edge insights into post-neurotrauma thrombotic events.The blood-brain barrier defends the brain and spinal cord against external assaults,and neutrophil extracellular trap involvement in blood-brain barrier disruption and immunothrombosis contributes substantially to secondary injuries in neurological diseases.Further research is needed to understand how neutrophil extracellular traps promote blood-brain barrier disruption and immunothrombosis,but recent studies have demonstrated that neutrophil extracellular traps play a crucial role in immunothrombosis,and identified modulators of neuro-immunothrombosis.However,these neurological diseases occur in blood vessels,and the mechanisms are unclear by which neutrophil extracellular traps penetrate the blood-brain barrier to participate in immunothrombosis in traumatic brain injury.This review discusses the role of neutrophil extracellular traps in neuro-immunothrombosis and explores potential therapeutic interventions to modulate neutrophil extracellular traps that may reduce immunothrombosis and improve traumatic brain injury outcomes.

Machine learning based on metabolomics unveils neutrophil extracellular trap-related metabolic signatures in non-small cell lung cancer patients undergoing chemoimmunotherapy

BACKGROUND Non-small cell lung cancer(NSCLC)is the primary form of lung cancer,and the combination of chemotherapy with immunotherapy offers promising treatment options for patients suffering from this disease.However,the emergence of drug resistance significantly limits the effectiveness of these therapeutic strategies.Consequently,it is imperative to devise methods for accurately detecting and evaluating the efficacy of these treatments.AIM To identify the metabolic signatures associated with neutrophil extracellular traps(NETs)and chemoimmunotherapy efficacy in NSCLC patients.METHODS In total,159 NSCLC patients undergoing first-line chemoimmunotherapy were enrolled.We first investigated the characteristics influencing clinical efficacy.Circulating levels of NETs and cytokines were measured by commercial kits.Liquid chromatography tandem mass spectrometry quantified plasma metabolites,and differential metabolites were identified.Least absolute shrinkage and selection operator,support vector machine-recursive feature elimination,and random forest algorithms were employed.By using plasma metabolic profiles and machine learning algorithms,predictive metabolic signatures were established.RESULTS First,the levels of circulating interleukin-8,neutrophil-to-lymphocyte ratio,and NETs were closely related to poor efficacy of first-line chemoimmunotherapy.Patients were classed into a low NET group or a high NET group.A total of 54 differential plasma metabolites were identified.These metabolites were primarily involved in arachidonic acid and purine metabolism.Three key metabolites were identified as crucial variables,including 8,9-epoxyeicosatrienoic acid,L-malate,and bis(monoacylglycerol)phosphate(18:1/16:0).Using metabolomic sequencing data and machine learning methods,key metabolic signatures were screened to predict NET level as well as chemoimmunotherapy efficacy.CONCLUSION The identified metabolic signatures may effectively distinguish NET levels and predict clinical benefit from chemoimmunotherapy in NSCLC patients.

Crossroads:Pathogenic role and therapeutic targets of neutrophil extracellular traps in rheumatoid arthritis

Rheumatoid arthritis(RA)is a prevalent autoimmune disease whose main features include chronic synovial inflammation,bone destruction,and joint degeneration.Neutrophils are often considered to be the first responders to inflammation and are a key presence in the inflammatory milieu of RA.Neutrophil extracellular traps(NETs),a meshwork of DNA-histone complexes and proteins released by activated neutrophils,are widely involved in the pathophysiology of autoimmune diseases,especially RA,in addition to playing a key role in the neutrophil innate immune response.NETs have been found to be an important source of citrullinated autoantigen antibodies and inflammatory factor release,which can activate RA synovial fibroblasts(FLS)and cause joint damage.This article reviews the role of NETs in the pathophysiology of RA,demonstrating the application of multiple molecules with various therapies,with a view to informing the discovery and development of novel biomarkers and therapeutic targets for RA.

Inhibiting the formation of neutrophil extracellular trapping: a potential mechanism of Chinese medicine in the treatment of ischemic stroke

Ischemic stroke(IS)is the main killer that endangers the health and life of middle-aged and elderly people worldwide.Inflammatory response plays a key regulatory role in the pathogenesis of IS.After cerebral ischemia,leukocytes rapidly accumulate,penetrate blood vessels and infiltrate brain tissue,thereby activating pro-inflammatory factors in the infarct area to exacerbate nerve damage.Neutrophil extracellular traps(NETs)are fibrous mesh structures released by activated neutrophils outside the cell,which can clear pathogens and cell debris,induce inflammatory responses and exacerbate cerebral ischemia-reperfusion(CI/R)injury.Various traditional Chinese medicines and their main components can improve neurological function defects after IS,and inhibit the formation of NETs,which opens up a new direction for the study of traditional Chinese medicines in the prevention and treatment of IS.

Hypobaric Hypoxia Aggravates Renal Injury by Inducing the Formation of Neutrophil Extracellular Traps through the NF-κB Signaling Pathway

Objective The hypersensitivity of the kidney makes it susceptible to hypoxia injury.The involvement of neutrophil extracellular traps(NETs)in renal injury resulting from hypobaric hypoxia(HH)has not been reported.In this study,we aimed to investigate the expression of NETs in renal injury induced by HH and the possible underlying mechanism.Methods A total of 24 SD male rats were divided into three groups(n=8 each):normal control group,hypoxia group and hypoxia+pyrrolidine dithiocarbamate(PDTC)group.Rats in hypoxia group and hypoxia+PDTC group were placed in animal chambers with HH which was caused by simulating the altitude at 7000 meters(oxygen partial pressure about 6.9 kPa)for 7 days.PDTC was administered at a dose of 100 mg/kg intraperitoneally once daily for 7 days.Pathological changes of the rat renal tissues were observed under a light microscope;the levels of serum creatinine(SCr),blood urea nitrogen(BUN),cell-free DNA(cf-DNA)and reactive oxygen species(ROS)were measured;the expression levels of myeloperoxidase(MPO),citrullinated histone H3(cit-H3),B-cell lymphoma 2(Bcl-2),Bax,nuclear factor kappa B(NF-κB)p65 and phospho-NF-κB p65(p-NF-κB p65)in rat renal tissues were detected by qRT-qPCR and Western blotting;the localization of NF-κB p65 expression in rat renal tissues was observed by immunofluorescence staining and the expression changes of NETs in rat renal tissues were detected by multiplex fluorescence immunohistochemical staining.Results After hypoxia,the expression of NF-κB protein in renal tissues was significantly increased,the levels of SCr,BUN,cf-DNA and ROS in serum were significantly increased,the formation of NETs in renal tissues was significantly increased,and a large number of tubular dilatation and lymphocyte infiltration were observed in renal tissues.When PDTC was used to inhibit NF-κB activation,NETs formation in renal tissue was significantly decreased,the expression level of Bcl-2 in renal tissues was significantly increased,the expression level of Bax was significantly decreased,and renal injury was significantly alleviated.Conclusion HH induces the formation of NETs through the NF-κB signaling pathway,and it promotes apoptosis and aggravates renal injury by decreasing Bcl-2 and increasing Bax expression.

Blood neutrophil extracellular traps:a novel target for the assessment of mammary health in transition dairy cows

Background:Mammary health is important for transition dairy cows and has been well recognized to exert decisive effects on animal welfare.However,the factors influencing mammary health are still unclear.Differential somatic cell count(DSCC)could reflect the mastitis risk since it is the percentage of neutrophils plus lymphocytes in total somatic cells and could be reflective of mammary health of dairy cows.This work aimed to investigate the assessment and prognosis of the health of transition cows based on blood neutrophil extracellular traps(NETs).Results:Eighty-four transition Holstein dairy cows were selected.The serum was sampled in all the animals at week 1 pre-and postpartum,and milk was sampled at week 1 postpartum.Based on the DSCC in milk at week 1,cows with lower(7.4%±4.07%,n=15)and higher(83.3%±1.21%,n=15)DSCCs were selected.High DSCC cows had higher levels of red blood cell counts(P<0.05),hemoglobin(P=0.07),and hematocrit(P=0.05),higher concentrations of serum oxidative variables[reactive oxygen species(P<0.05),malondialdehyde(P<0.05),protein carbonyl(P<0.05),and 8-hydroxy-2-deoxyguanosine(P=0.07)],higher levels of serum and milk NETs(P<0.05)and blood-milk barrier indicators,including serumβ-casein(P=0.05)and milk immunoglobulin G2(P=0.09),than those of low DSCC cows.In addition,lower concentrations of serum nutrient metabolites(cholesterol and albumin)(P<0.05)and a lower level of serum deoxyribonuclease I(P=0.09)were observed in high DSCC cows than in low DSCC cows.Among the assessments performed using levels of the three prepartum serum parameters(NETs,deoxyribonuclease I andβ-casein),the area under the curve(0.973)of NETs was the highest.In addition,the sensitivity(1.00)and specificity(0.93)were observed for the discrimination of these cows using NETs levels with a critical value of 32.2 ng/mL(P<0.05).Conclusions:The formation of NETs in blood in transition dairy cows may damage the integrity of the blood-milk barrier and thereby increase the risk for mastitis in postpartum cows.

Neutrophil extracellular traps mediate the crosstalk between glioma progression and the tumor microenvironment via the HMGB1/RAGE/IL-8 axis

Objective:Neutrophil extracellular traps(NETs)produced by tumor-infiltrating neutrophils(TINs)are associated with poor prognosis in patients with several types of cancer.However,the mechanisms underlying the involvement of NETs in glioma progression remain largely unknown.This study aimed to elucidate the roles of NETs in biological processes that drive the crosstalk between glioma progression and the tumor microenvironment.Methods:Neutrophil infiltration and NETs formation were investigated in glioma tissue through immunohistochemistry,and their relationships with clinicopathological features and outcomes were statistically evaluated.The effects of NETs on glioma cell progression were studied in a co-culture system.In vivo and in vitro experiments validated the reactive oxygen species activity and cytokine production of TINs,as well as the ERK signaling pathway activation and the metastasis of gliomas.Results:Neutrophil infiltration and NETs formation were induced in high-grade glioma compared with low-grade glioma.NETs induced by TINs were determined to be an oncogenic marker of high-grade gliomas and to be involved in cell proliferation and invasion.NETs overproduction promoted glioma cell proliferation,migration,and invasion.Furthermore,HMGB1 was found to bind to RAGE and activate the NF-κB signaling pathway in vitro.In addition,NETs stimulated the NF-κB signaling pathway,thus promoting IL-8 secretion in glioblastoma.Subsequently,IL-8 recruited neutrophils which in turn mediated NETs formation via the PI3 K/AKT/ROS axis in TINs.Conclusions:Our results suggest that NETs produced by TINs mediate the crosstalk between glioma progression and the tumor microenvironment by regulating the HMGB1/RAGE/IL-8 axis.Targeting NETs formation or IL-8 secretion may be an effective approach to inhibit glioma progression.

Neutrophil extracellular traps participate in the development of cancer-associated thrombosis in patients with gastric cancer

BACKGROUND The development of venous thromboembolism(VTE) is associated with high mortality among gastric cancer(GC) patients. Neutrophil extracellular traps(NETs) have been reported to correlate with the prothrombotic state in some diseases, but are rarely reported in GC patients.AIM To investigate the effect of NETs on the development of cancer-associated thrombosis in GC patients.METHODS The levels of NETs in blood and tissue samples of patients were analyzed by ELISA, flow cytometry, and immunofluorescence staining. NET generation and hypercoagulation of platelets and endothelial cells(ECs) in vitro were observed by immunofluorescence staining. NET procoagulant activity(PCA) was determined by fibrin formation and thrombin–antithrombin complex(TAT) assays.Thrombosis in vivo was measured in a murine model induced by flow stenosis in the inferior vena cava(IVC).RESULTS NETs were likely to form in blood and tissue samples of GC patients compared with healthy individuals. In vitro studies showed that GC cells and their conditioned medium, but not gastric mucosal epithelial cells, stimulated NET release from neutrophils. In addition, NETs induced a hypercoagulable state of platelets by upregulating the expression of phosphatidylserine and Pselectin on the cells. Furthermore, NETs stimulated the adhesion of normal platelets on glass surfaces. Similarly, NETs triggered the conversion of ECs to hypercoagulable phenotypes by downregulating the expression of their intercellular tight junctions but upregulating that of tissue factor. Treatment of normal platelets or ECs with NETs augmented the level of plasma fibrin formation and the TAT complex. In the models of IVC stenosis, tumor-bearing mice showed a stronger ability to form thrombi, and NETs abundantly accumulated in the thrombi of tumorbearing mice compared with control mice. Notably, the combination of deoxyribonuclease I,activated protein C, and sivelestat markedly abolished the PCA of NETs.CONCLUSION GC-induced NETs strongly increased the risk of VTE development both in vitro and in vivo. NETs are potential therapeutic targets in the prevention and treatment of VTE in GC patients.

Neutrophil extracellular traps in gastrointestinal cancer

Gastrointestinal(GI)cancer is a high-risk malignancy and is characterized by high mortality and morbidity worldwide.Neutrophil extracellular traps(NETs),a weblike structure consisting of chromatin DNA with interspersed cytoplasmic and granule proteins,are extruded by activated neutrophils to entrap and kill bacteria and fungi.However,accumulating evidence shows that NETs are related to the progression and metastasis of cancer.In clinical studies,NETs infiltrate primary GI cancer tissues and are even more abundant in metastatic lesions.The quantity of NETs in peripheral blood is revealed to be associated with ascending clinical tumour stages,indicating the role of NETs as a prognostic markers in GI cancer.Moreover,several inhibitors of NETs or NET-related proteins have been discovered and used to exert anti-tumour effects in vitro or in vivo,suggesting that NETs can be regarded as targets in the treatment of GI cancer.In this review,we will focus on the role of NETs in gastric cancer and colorectal cancer,generalizing their effects on tumour-related thrombosis,invasion and metastasis.Recent reports are also listed to show the latest evidences of how NETs affect GI cancer.Additionally,notwithstanding the scarcity of systematic studies elucidating the underlying mechanisms of the interaction between NETs and cancer cells,we highlight the potential importance of NETs as biomarkers and anti-tumour therapeutic targets.

Neutrophil extracellular traps in the intestinal mucosa of Eimeria-infected animals

Objective:To investigate the presence of neutrophil extracellular traps(NETs) in vivo by analysing intestinal sections from experimentally Eimeria bovis-and naturally Eimeria arloingi-infected animals.Methods:Intestinal samples of Eimeria arloingi-and Eimeria bovis-infected animals were analysed by using immunohistochemical and fluorescence approach by using monoclonal antibodies.Results:Classical NET components were confirmed by co-localization of extracellular DNA being decorated with neutrophil elastase and histones in Eimeria-infected tissue samples.Here,extrusion of NETs was exclusively detected in intestinal polymorphonuclear neutrophils infiltrating Eimeria-infected sites.In vivo NETs were either found in close proximity or in direct contact to different Eimeria stages suggesting a stage-independent process.NETs were also found within the gut lumen driven by polymorphonuclear neutrophils that were contacting released oocysts.Conclusions:We postulate that NETs might play an important role in innate defence reactions in coccidiosis therefore significantly altering the outcome of infection.

Hsa_circ_0036740 in familial adenomatous polyposis:Immune regulation and neutrophil effects in CRC based on highthroughput assay

Familial adenomatous polyposis(FAP)is an autosomal dominant disease with a high probability of becoming cancerous.Many RNAs potentially associated with FAP have not been identified.In this study,a circRNA(circular RNA)expression profile of FAP was established using a circRNA microarray,and differentially expressed circRNAs were verified by RT-qPCR.The effects of hsa_circ_0036740 on the malignant behavior of tumor cells(proliferation,apoptosis,and epithelial mesenchymal transition)and the levels of C3A complement protein expression were evaluated.Moreover,neutrophils were isolated and co-cultured with colorectal cancer cells(CRCs),followed by measurements of MPO-DNA,citrullinated histone H3,interleukin(IL)-1β,IL-6,and IL-8 levels.Nuclear translocation of arginine deiminase 4(PAD4)was observed using immunofluorescence assays.Based on the high-throughput assay,238 downregulated circRNAs,and 38 upregulated circRNAs were identified.A Kyoto Encyclopedia of Genes and Genomes enrichment analysis suggested that immune regulation might be involved in FAP.A total of 10 DECs(differentially expressed circular RNAs)were identified by RT-qPCR,and among them,hsa_circ_0036740 showed the highest fold-change in upregulation.Results of gain-of-and loss-of-function studies revealed that hsa_circ_0036740 enhanced the malignant behavior of tumor cells,such as metastasis,proliferation,and apoptosis,with an increasing level of C3A complement.Moreover,hsa_circ_0036740 also significantly increased neutrophil extracellular trap formation and inflammation in neutrophils,as shown by an increased expression of PAD4.In conclusion,this study revealed the expression profiles of circRNAs in FAP and confirmed the possible involvement of hsa_circ_0036740 in the immune regulation mediated by neutrophils.Finally,hsa_circ_0036740 was suggested as a new therapeutic target for CRC.

A crucial role of neutrophil extracellular traps in pulmonary infectious diseases

Neutrophil extracellular traps(NETs),extrusions of intracellular DNA with attached granular material that exert an antibacterial effect through entangling,isolating,and immobilizing microorganisms,have been extensively studied in recent decades.The primary role of NETs is to entrap and facilitate the killing of bacteria,fungi,viruses,and parasites,preventing bacterial and fungal dissemination.NET formation has been described in many pulmonary diseases,including both infectious and non-infectious.NETs are considered a double-edged sword.As innate immune cells,neutrophils release NETs to kill pathogens and remove cellular debris.However,the dele-terious effects of excessive NET release in lung disease are particularly important because NETs and by-products of NETosis can directly induce epithelial and endothelial cell death while simultaneously inducing inflammatory cytokine secretion and immune-mediated thrombosis.Thus,NET formation must be tightly regulated to preserve the anti-microbial capability of NETs while minimizing damage to the host.In this review,we summarized the recent updates on the mechanism of NETs formation and pathophysiology associated with excessive NETs,aiming to provide insights for research and treatment of pulmonary infectious diseases.

The Mechanisms of SAA/TLR4 Inducing Angiogenesis in Rheumatoid Arthritis through NETs Formation

Objective: Rheumatoid arthritis (RA) is an autoimmune disease in which angiogenesis represents a critical early event of synovial inflammation. The present study aimed to reveal the potential molecular mechanisms of SAA/TLR4 induction of angiogenesis through NETs in RA. Materials and methods: Firstly, immunohistochemistry and immunofluorescence were used to determinate TLR4 and NETs expression in synovial tissue, respectively. ELISA was used to detect the content of SAA, MPO and NE in serum and synovial fluid of patients. DNA quantification was done by fluorescence. DNA fluorescence staining was used to compare NETs formation in RA and HC sera, and to investigate the mechanism of NETs formation induced by SAA stimulation. PicoGreen DNA testing was used to characterize the DNA in the supernatants. Also, DNA fluorescence staining to explore whether NETs formation induced by SAA was dependent or independent on NADPH oxidase pathway. MTT assay, Wound healing assay, Tube formation assay were performed to analyze human veins umbilical cells (HUVECs) proliferation, migration, and tube vessels formation, respectively under NETs or NETs + DNase stimulants. Results: Firstly, we demonstrated that TLR4 was predominantly and widely expressed in synovial tissues with elevated serum levels of SAA, compared to osteoarthritis (OA) patients, and the similar results were observed for NETs formation. Afterwards, in a series of in vitro experiments, we reported an increased MPO and NE levels, and a relatively decreased DNA level in the sera of RA patients. Set apart, the levels of MPO and NE in RA were correlated to the disease activity. Moreover, an increased spontaneous NETs formation was observed in RA patients, enhanced under SAA stimulation and regulated by TLR4 activation. And the total DNA expressed in RA patients was partly composed of NET-DNA. Also, SAA induced NETs formation dependent on NADPH pathway. Finally, our results indicated that extracted SAA-induced NETs promoted endothelial cells (ECs) migration, proliferation, and vascular tube formation. Conclusion: Our current study highlighted the role of SAA/TLR4 interaction in the induction of angiogenesis through formed NETs. Therefore, this study offers new perspectives in the understanding of RA pathogenicity and its management.

Elevated neutrophil extracellular traps by HBV-mediated S100A9-TLR4/RAGE-ROS cascade facilitate the growth and metastasis of hepatocellular carcinoma

Background:Neutrophil extracellular traps(NETs)are considered significant contributors to cancer progression,especially metastasis.However,it is still unclear whether NETs are involved in hepatitis B virus(HBV)-related hepatocarcinogenesis and have potential clinical significance during evaluation and management for hepatocellular carcinoma(HCC).In this study,we aimed to investigate the functional mechanism of NETs in HBV-related hepatocarcinogenesis and their clinical significance.Methods:A total of 175 HCC patients with and without HBV infection and 58 healthy controls were enrolled in this study.NETs weremeasured in tissue specimens,freshly isolated neutrophils and blood serum from these patients,and the correlation of circulating serum NETs levels with malignancy was evaluated.The mechanism by which HBV modulates NETs formation was explored using cell-based studies.In addition,in vitro and in vivo experiments were further performed to clarify the functional mechanism of NETs on the growth and metastasis of HCC.Results:We observed an elevated level of NETs in blood serum and tissue specimens from HCC patients,especially those infected with HBV.NETs facilitated the growth and metastasis of HCC both in vitro and in vivo,which were mainly dominated by increased angiogenesis,epithelial-mesenchymal transition(EMT)-related cell migration,matrix metalloproteinases(MMPs)-induced extracellular matrix(ECM)degradation and NETs-mediated cell trapping.Inhibition of NETs generation by DNase 1 effectively abrogated the NETs-aroused HCC growth and metastasis.In addition,HBV-induced S100A9 accelerated the generation of NETs,which was mediated by activation of toll-like receptor(TLR4)/receptor for advanced glycation end products(RAGE)-reactive oxygen species(ROS)signaling.Further,circulatory NETs were found to correlate with viral load,TNM stage and metastasis status in HBV-related HCC,and the identified NETs could predict extrahepatic metastasis,with an area under the ROC curve(AUC)of 0.83 and 90.3%sensitivity and 62.8%specificity at a cutoff value of 0.32.Conclusions:Our findings indicated that activation of RAGE/TLR4-ROS signaling by HBV-induced S100A9 resulted in abundant NETs formation,which subsequently facilitated the growth and metastasis of HCC cells.More importantly,the identified circulatory NETs exhibited potential as an alternative biomarker for predicting extrahepatic metastasis in HBV-related HCC.

Novel neutrophil extracellular trap-related mechanisms in diabetic wounds inspire a promising treatment strategy with hypoxia-challenged small extracellular vesicles

Neutrophil extracellular traps(NETs)have been considered a significant unfavorable factor for wound healing in diabetes,but the mechanisms remain unclear.The therapeutic application of small extracellular vesicles(sEVs)derived from mesenchymal stem cells(MSCs)has received considerable attention for their properties.Hypoxic preconditioning is reported to enhance the therapeutic potential of MSC-derived sEVs in regenerative medicine.Therefore,the aim of this study is to illustrate the detailed mechanism of NETs in impairment of diabetic wound healing and develop a promising NET-targeting treatment based on hypoxic pretreated MSC-derived sEVs(Hypo-sEVs).Excessive NETs were found in diabetic wounds and in high glucose(HG)-induced neutrophils.Further research showed that high concentration of NETs impaired the function of fibroblasts through activating endoplasmic reticulum(ER)stress.Hypo-sEVs efficiently promoted diabetic wound healing and reduced the excessive NET formation by transferring miR-17-5p.Bioinformatic analysis and RNA interference experiment revealed that miR-17-5p in Hypo-sEVs obstructed the NET formation by targeting TLR4/ROS/MAPK pathway.Additionally,miR-17-5p overexpression decreased NET formation and overcame NET-induced impairment in fibroblasts,similar to the effects of Hypo-sEVs.Overall,we identify a previously unrecognized NET-related mechanism in diabetic wounds and provide a promising NET-targeting strategy for wound treatment.

Pancreatic melatonin enhances anti-tumor immunity in pancreatic adenocarcinoma through regulating tumor-associated neutrophils infiltration and NETosis

Tumor microenvironment contributes to poor prognosis of pancreatic adenocarcinoma(PAAD)patients.Proper regulation could improve survival.Melatonin is an endogenous hormone that delivers multiple bioactivities.Here we showed that pancreatic melatonin level is associated with patients'survival.In PAAD mice models,melatonin supplementation suppressed tumor growth,while blockade of melatonin pathway exacerbated tumor progression.This anti-tumor effect was independent of cytotoxicity but associated with tumor-associated neutrophils(TANs),and TANs depletion reversed effects of melatonin.Melatonin induced TANs infiltration and activation,therefore induced cell apoptosis of PAAD cells.Cytokine arrays revealed that melatonin had minimal impact on neutrophils but induced secretion of Cxcl2 from tumor cells.Knockdown of Cxcl2 in tumor cells abolished neutrophil migration and activation.Melatonin-induced neutrophils presented an N1-like anti-tumor phenotype,with increased neutrophil extracellular traps(NETs)causing tumor cell apoptosis through cell-to-cell contact.Proteomics analysis revealed that this reactive oxygen species(ROS)-mediated inhibition was fueled by fatty acid oxidation(FAO)in neutrophils,while FAO inhibitor abolished the anti-tumor effect.Analysis of PAAD patient specimens revealed that CXCL2 expression was associated with neutrophil infiltration.CXCL2,or TANs,combined with NET marker,can better predict patients'prognosis.Collectively,we discovered an anti-tumor mechanism of melatonin through recruiting N1-neutrophils and beneficial NET formation.

Shifting focus from bacteria to host neutrophil extracellular traps of biodegradable pure Zn to combat implant centered infection

The widespread use of orthopedic implants to support or replace bones is increasingly threatened by the risk of incurable bacterial infections,impenetrable microbial biofilms,and irreversible antibiotic resistance.In the past,the development of anti-infective biomaterials focused solely on direct antibacterial properties while ignoring the host’s immune response.Inspired by the clearance of infection by the innate neutrophil response and partici-pation in anti-infectious immunity of Zn ions,we report an innovative neutrophil extracellular traps(NETs)strategy,induced by biodegradable pure Zn,which achieved therapeutic efficacy toward biomaterial-related infections.Our in vitro and in vivo data showed that pure Zn was favorable for NETs formation by promoting the release of DNA fibers and granule proteins in a reactive oxygen species(ROS)-dependent manner,thereby retraining and degrading bacteria with an efficiency of up to 99.5%.Transcriptome analysis revealed that cytoskeletal rearrangement and toll-like receptor(TLR)signaling pathway were also involved in Zn-induced NETs formation.Furthermore,the in vivo results of a Staphylococcus aureus(S.aureus)-infected rat model veri-fied that pure Zn potentiated the bactericidal capability of neutrophils around implants,and promoted osseointegration in S.aureus-infected rat femurs.This antibacterial immunity concept lays a foundation for the development of other antibacterial biomaterials and holds great promise for treating orthopedic infections.

Substance P promotes epidural fibrosis via induction of type 2 macrophages

In response to spinal surgery,neurons secrete a large amount of substance P into the epidural area.Substance P is involved in macrophage differentiation and fibrotic disease.However,the specific roles and mechanisms of substance P in epidural fibrosis remain unclear.In this study,we established a mouse model of L1–L3 laminectomy and found that dorsal root ganglion neurons and the macrophages infiltrating into the wound area released sphingolipids.In vitro experiments revealed that type 1 macrophages secreted substance P,which promoted differentiation of type 1 macrophages towards a type 2 phenotype.High-throughput mRNA-seq analysis revealed that the sphingolipid metabolic pathway may be involved in the regulation of type 2 macrophages by substance P.Specifically,sphingomyelin synthase 2,a component of the sphingolipid metabolic pathway,promoted M2 differentiation in substance P-treated macrophages,while treating the macrophages with LY93,a sphingomyelin synthase 2 inhibitor,suppressed M2 differentiation.In addition,substance P promoted the formation of neutrophil extracellular traps,which further boosted M2 differentiation.Blocking substance P with the neurokinin receptor 1 inhibitor RP67580 decreased the number of M2 macrophages in the wound area after spinal surgery and alleviated epidural fibrosis,as evidenced by decreased fibronectin,α-smooth muscle actin,and collagen I in the scar tissue.These results demonstrated that substance P promotes M2 macrophage differentiation in epidural fibrosis via sphingomyelin synthase 2 and neutrophil extracellular traps.These findings provide a novel strategy for the treatment of epidural fibrosis.

Wip1 inhibits neutrophil extracellular traps to promote abscess formation in mice by directly dephosphorylating Coronin-1a

Neutrophil extracellular traps (NETs) participate in the rapid inhibition and clearance of pathogens during infection;however, the molecular regulation of NET formation remains poorly understood. In the current study, we found that inhibition of the wild-type p53-induced phosphatase 1 (Wip1) significantly suppressed the activity of Staphylococcus aureus (S. aureus) and accelerated abscess healing in S. aureus-induced abscess model mice by enhancing NET formation. A Wip1 inhibitor significantly enhanced NET formation in mouse and human neutrophils in vitro. High-resolution mass spectrometry and biochemical assays demonstrated that Coro1a is a substrate of Wip1. Further experiments also revealed that Wip1 preferentially and directly interacts with phosphorylated Coro1a than compared to unphosphorylated inactivated Coro1a. The phosphorylated Ser426 site of Coro1a and the 28–90 aa domain of Wip1 are essential for the direct interaction of Coro1a and Wip1 and for Wip1 dephosphorylation of p-Coro1a Ser426. Wip1 deletion or inhibition in neutrophils significantly upregulated the phosphorylation of Coro1a-Ser426, which activated phospholipase C and subsequently the calcium pathway, the latter of which promoted NET formation after infection or lipopolysaccharide stimulation. This study revealed Coro1a to be a novel substrate of Wip1 and showed that Wip1 is a negative regulator of NET formation during infection. These results support the potential application of Wip1 inhibitors to treat bacterial infections.

Therapeutic ACPA inhibits NET formation: a potential therapy for neutrophil-mediated inflammatory diseases

Excessive release of neutrophil extracellular traps(NETs)is associated with disease severity and contributes to tissue injury,followed by severe organ damage.Pharmacological or genetic inhibition of NET release reduces pathology in multiple inflammatory disease models,indicating that NETs are potential therapeutic targets.Here,we demonstrate using a preclinical basket approach that our therapeutic anti-citrullinated protein antibody(tACPA)has broad therapeutic potential.Treatment with tACPA prevents disease symptoms in various mouse models with plausible NET-mediated pathology,including inflammatory arthritis(IA),pulmonary fibrosis,inflammatory bowel disease and sepsis.We show that citrulline residues in the N-termini of histones 2A and 4 are specific targets for therapeutic intervention,whereas antibodies against other N-terminal post-translational histone modifications have no therapeutic effects.Because citrullinated histones are generated during NET release,we investigated the ability of tACPA to inhibit NET formation.tACPA suppressed NET release from human neutrophils triggered with physiologically relevant human disease-related stimuli.Moreover,tACPA diminished NET release and potentially initiated NET uptake by macrophages in vivo,which was associated with reduced tissue damage in the joints of a chronic arthritis mouse model of IA.To our knowledge,we are the first to describe an antibody with NET-inhibiting properties and thereby propose tACPA as a drug candidate for NET-mediated inflammatory diseases,as it eliminates the noxious triggers that lead to continued inflammation and tissue damage in a multidimensional manner.