Neutrophil Extracellular Traps: Signaling Properties and Disease Relevance. Mediators Inflamm. 2020;2020:9254087. [PMID: 32774152 PMCID: PMC7407020 DOI: 10.1155/2020/9254087]

Bacterial endometritis-induced changes in the endometrial proteome in mares: Potential uterine biomarker for bacterial endometritis

Equine endometritis is one of the main causes of subfertility in the mare. Unraveling the molecular mechanisms involved in this condition and pinpointing proteins with biomarker potential could be crucial in both diagnosing and treating this condition. This study aimed to identify the endometritis-induced changes in the endometrial proteome in mares and to elucidate potential biological processes in which these proteins may be involved. Secondly, biomarkers related to bacterial endometritis (BE) in mares were identified. Uterine lavage fluid samples were collected from 28 mares (14 healthy: negative cytology and culture, and no clinical signs and 14 mares with endometritis: positive cytology and culture, in addition to clinical signs). Proteomic analysis was performed with a UHPLC-MS/MS system and bioinformatic analysis was carried out using Qlucore Omics Explorer. Gene Ontology enrichment and pathway analysis (PANTHER and KEGG) of the uterine proteome were performed to identify active biological pathways in enriched proteins from each group. Quantitative analysis revealed 38 proteins differentially abundant in endometritis mares when compared to healthy mares (fold changes >4.25, and q-value = 0.002). The proteins upregulated in the secretome of mares with BE were involved in biological processes related to the generation of energy and REDOX regulation and to the defense response to bacterium. A total of 24 biomarkers for BE were identified using the biomarker workbench algorithm. Some of the proteins identified were related to the innate immune system such as isoforms of histones H2A and H2B involvement in neutrophil extracellular trap (NET) formation, complement C3a, or gelsolin and profilin, two actin-binding proteins which are essential for dynamic remodeling of the actin cytoskeleton during cell migration. The other group of biomarkers were three known antimicrobial peptides (lysosome, equine cathelicidin 2 and myeloperoxidase (MPO)) and two uncharacterized proteins with a high homology with cathelicidin families. Findings in this study provide the first evidence that innate immune cells in the equine endometrium undergo reprogramming of metabolic pathways similar to the Warburg effect during activation. In addition, biomarkers of BE in uterine fluid of mares including the new proteins identified, as well as other antimicrobial peptides already known, offer future lines of research for alternative treatments to antibiotics.

Ischemic Stroke with Comorbid Cancer Has Specific miRNA-mRNA Networks in Blood That Vary by Ischemic Stroke Mechanism

OBJECTIVE

Approximately half of ischemic strokes (IS) in cancer patients are cryptogenic, with many presumed cardioembolic. We evaluated whether there were specific miRNA and mRNA transcriptome architectures in peripheral blood of IS patients with and without comorbid cancer, and between cardioembolic versus noncardioembolic IS etiologies in comorbid cancer.

METHODS

We studied patients with cancer and IS (CS; n = 42), stroke only (SO; n = 41), and cancer only (n = 28), and vascular risk factor-matched controls (n = 30). mRNA-Seq and miRNA-Seq data, analyzed with linear regression models, identified differentially expressed genes in CS versus SO and in cardioembolic versus noncardioembolic CS, and miRNA-mRNA regulatory pairs. Network-level analyses identified stroke etiology-specific responses in CS.

RESULTS

A total of 2,085 mRNAs and 31 miRNAs were differentially expressed between CS and SO. In CS, 122 and 35 miRNA-mRNA regulatory pairs, and 5 and 3 coexpressed gene modules, were associated with cardioembolic and noncardioembolic CS, respectively. Complement, growth factor, and immune/inflammatory pathways showed differences between IS etiologies in CS. A 15-gene biomarker panel assembled from a derivation cohort (n = 50) correctly classified 81% of CS and 71% of SO participants in a validation cohort (n = 33). Another 15-gene panel correctly identified etiologies for 13 of 13 CS-cardioembolic and 11 of 11 CS-noncardioembolic participants upon cross-validation; 11 of 16 CS-cryptogenic participants were predicted cardioembolic.

INTERPRETATION

We discovered unique mRNA and miRNA transcriptome architecture in CS and SO, and in CS with different IS etiologies. Cardioembolic and noncardioembolic etiologies in CS showed unique coexpression networks and potential master regulators. These may help distinguish CS from SO and identify IS etiology in cryptogenic CS patients. ANN NEUROL 2024.

Inflammatory proteins and neutrophil extracellular traps increase in burn blister fluid 24h after burn

Burn wound blister fluid is a valuable matrix for understanding the biological pathways associated with burn injury. In this study, 152 blister fluid samples collected from paediatric burn wounds at three different hospitals were analysed using mass spectrometry proteomic techniques. The protein abundance profile at different days after burn indicated more proteins were associated with cellular damage/repair in the first 24 h, whereas after this point more proteins were associated with antimicrobial defence. The inflammatory proteins persisted at a high level in the blister fluid for more than 7 days. This may indicate that removal of burn blisters prior to two days after burn is optimal to prevent excessive or prolonged inflammation in the wound environment. Additionally, many proteins associated with the neutrophil extracellular trap (NET) pathway were increased after burn, further implicating NETs in the post-burn inflammatory response. NET inhibitors may therefore be a potential treatment to reduce post-burn inflammation and coagulation pathology and enhance burn wound healing outcomes.

Histone content, and thus DNA content, is associated with differential in vitro lysis of acute ischemic stroke clots

BACKGROUND

Fibrin, von Willebrand factor, and extracellular DNA from neutrophil extracellular traps all contribute to acute ischemic stroke thrombus integrity.

OBJECTIVES

In this study, we explored how the proteomic composition of retrieved thromboemboli relates to susceptibility to lysis with distinct thrombolytics.

METHODS

Twenty-six retrieved stroke thromboemboli were portioned into 4 segments, with each subjected to 1 hour of in vitro lysis at 37 °C in 1 of 4 solutions: tissue plasminogen activator (tPA), tPA + von Willebrand factor-cleaving ADAMTS-13, tPA + DNA-cleaving deoxyribonuclease (DNase) I, and all 3 enzymes. Lysis, characterized by the percent change in prelysis and postlysis weight, was compared across the solutions and related to the corresponding abundance of proteins identified on mass spectrometry for each of the thromboemboli used in lysis.

RESULTS

Solutions containing DNase resulted in approximately 3-fold greater thrombolysis than that with the standard-of-care tPA solution (post hoc Tukey, P < .01 for all). DNA content was directly related to lysis in solutions containing DNase (Spearman's ρ > 0.39 and P < .05 for all significant histones) and inversely related to lysis in solutions without DNase (Spearman's ρ < -0.40 and P < .05 for all significant histones). Functional analysis suggests distinct pathways associated with susceptibility to thrombolysis with tPA (platelet-mediated) or DNase (innate immune system-mediated).

CONCLUSION

This study demonstrates synergy of DNase and tPA in thrombolysis of stroke emboli and points to DNase as a potential adjunct to our currently limited selection of thrombolytics in treating acute ischemic stroke.

Targeting neutrophil extracellular traps: A novel strategy in hematologic malignancies

Neutrophil extracellular traps (NETs) have emerged as a critical factor in malignant hematologic disease pathogenesis. These structures, comprising DNA, histones, and cytoplasmic proteins, were initially recognized for their role in immune defense against microbial threats. Growing evidence suggests that NETs contribute to malignant cell progression and dissemination, representing a double-edged sword. However, there is a paucity of reports on its involvement in hematological disorders. A comprehensive understanding of the intricate relationship between malignant cells and NETs is necessary to explore effective therapeutic strategies. This review highlights NET formation and mechanisms underlying disease pathogenesis. Moreover, we discuss recent advancements in targeted inhibitor development for selective NET disruption, empowering precise design and efficacious therapeutic interventions for malignant hematologic diseases.

Stroke emboli from patients with atrial fibrillation enriched with neutrophil extracellular traps

Background

Recent literature has demonstrated remarkable heterogeneity in the composition of acute ischemic stroke (AIS) emboli, which may impact susceptibility to therapy.

Objectives

In this study, we explored differences in proteomic composition of retrieved embolic material from patients with stroke with and without atrial fibrillation (AF) (AF+ and AF-, respectively).

Methods

The full proteome of retrieved thromboembolic material from 24 patients with AIS was obtained by mass spectrometry. Known marker proteins were assigned groups representing broad classes of embolus components: red blood cells, platelets, neutrophils, eosinophils, histones, complement, and other clotting-associated proteins (eg, fibrinogen). Relative protein abundances were compared between AF+ and AF- samples. Functional implications of differences were explored with gene set enrichment analysis and Gene Ontology enrichment analysis and visualization tool.

Results

One hundred sixty-six proteins were differentially expressed between AF+ and AF- specimens. Eight out of the 15 neutrophil proteins (P < .05; fold change, >2) and 4 of the 14 histone proteins were significantly enriched in AF+ emboli (P < .05; fold change, >2). Gene set enrichment analysis revealed a significant representation of proteins from published neutrophil extracellular trap (NET) proteomic gene sets. The most significantly represented functional Gene Ontology pathways in patients with AF involved neutrophil activation and degranulation (P < 1 × 10-7).

Conclusion

The present analysis suggests enrichment of NETs in emboli of patients with stroke and AF. NETs are a significant though understudied structural component of thrombi. This work suggests not only unique stroke biology in AF but also potential therapeutic targets for AIS in this population.

Chronic Thromboembolic Pulmonary Hypertension: A Review of the Multifaceted Pathobiology

Chronic thromboembolic pulmonary disease results from the incomplete resolution of thrombi, leading to fibrotic obstructions. These vascular obstructions and additional microvasculopathy may lead to chronic thromboembolic pulmonary hypertension (CTEPH) with increased pulmonary arterial pressure and pulmonary vascular resistance, which, if left untreated, can lead to right heart failure and death. The pathobiology of CTEPH has been challenging to unravel due to its rarity, possible interference of results with anticoagulation, difficulty in selecting the most relevant study time point in relation to presentation with acute pulmonary embolism (PE), and lack of animal models. In this article, we review the most relevant multifaceted cross-talking pathogenic mechanisms and advances in understanding the pathobiology in CTEPH, as well as its challenges and future direction. There appears to be a genetic background affecting the relevant pathological pathways. This includes genetic associations with dysfibrinogenemia resulting in fibrinolysis resistance, defective angiogenesis affecting thrombus resolution, and inflammatory mediators driving chronic inflammation in CTEPH. However, these are not necessarily specific to CTEPH and some of the pathways are also described in acute PE or deep vein thrombosis. In addition, there is a complex interplay between angiogenic and inflammatory mediators driving thrombus non-resolution, endothelial dysfunction, and vascular remodeling. Furthermore, there are data to suggest that infection, the microbiome, circulating microparticles, and the plasma metabolome are contributing to the pathobiology of CTEPH.

A Serological Neoepitope Biomarker of Neutrophil Elastase-Degraded Calprotectin, Associated with Neutrophil Activity, Identifies Idiopathic Pulmonary Fibrosis and Chronic Obstructive Pulmonary Disease More Effectively Than Total Calprotectin

Neutrophil activation can release neutrophil extracellular traps (NETs) in acute inflammation. NETs result in the release of human neutrophil elastase (HNE) and calprotectin, where the former can degrade the latter and generate protein fragments associated with neutrophil activity. We investigated this in chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF) using the novel neoepitope biomarker CPa9-HNE, quantifying a specific HNE-mediated fragment of calprotectin in serum. CPa9-HNE was compared to total calprotectin. Initially, CPa9-HNE was measured in healthy (n = 39), COPD (n = 67), and IPF (n = 16) serum using a neoepitope-specific competitive enzyme-linked immunosorbent assay. Then, a head-to-head comparison of CPa9-HNE and total calprotectin, a non-neoepitope, was conducted in healthy (n = 19), COPD (n = 25), and IPF (n = 19) participants. CPa9-HNE levels were significantly increased in COPD (p < 0.0001) and IPF subjects (p = 0.0001) when compared to healthy participants. Additionally, CPa9-HNE distinguished IPF (p < 0.0001) and COPD (p < 0.0001) from healthy participants more effectively than total calprotectin for IPF (p = 0.0051) and COPD (p = 0.0069). Here, CPa9-HNE also distinguished IPF from COPD (p = 0.045) participants, which was not observed for total calprotectin (p = 0.98). Neutrophil activity was significantly higher, as assessed via serum CPa9-HNE, for COPD and IPF compared to healthy participants. Additionally, CPa9-HNE exceeded the ability of non-neoepitope calprotectin serum measurements to separate healthy from lung disease and even COPD from IPF participants, indicating that neutrophil activity is essential for both COPD and IPF.

The role of neutrophil extracellular traps in sepsis and sepsis-related acute lung injury

Neutrophils release neutrophil extracellular traps (NETs) to trap pathogenic microorganisms. NETs are involved in the inflammatory response and bacterial killing and clearance. However, their excessive activation can lead to an inflammatory storm in the body, which may damage tissues and cause organ dysfunction. Organ dysfunction is the main pathophysiological cause of sepsis and also a cause of the high mortality rate in sepsis. Acute lung injury caused by sepsis accounts for the highest proportion of organ damage in sepsis. NET formation can lead to the development of sepsis because by promoting the release of interleukin-1 beta, interleukin-8, and tumor necrosis factor-alpha, thereby accelerating acute lung injury. In this review, we describe the critical role of NETs in sepsis-associated acute lung injury and review the current knowledge and novel therapeutic approaches.

The role of IL-6, ferritin, and coagulopathy in Covid-19 clinical progression

Background In COVID-19, the release of pro-inflammatory mediators in the cytokine storm, primarily interleukin-6 (IL-6), has been hypothesized to induce pulmonary intravascular coagulation. However, the relationship between IL-6 and coagulopathy remains unclear in COVID-19 progression. We aimed to investigate the correlation of IL-6 with D-dimer, fibrinogen, prothrombin time (PT), and ferritin. Furthermore, we also analyzed the effect of those parameters on the worsening of COVID-19 patients. Methods A prospective cohort study was conducted in moderate and severe COVID-19 patients from June 2020 to January 2021. A serial evaluation of IL-6, D-dimer, fibrinogen, ferritin, and PT was performed and correlated with the patient's condition at admission and on the 14th day. The outcomes (improvement, worsening, or discharged patients) were recorded during the study. Results Of 374 patients, 73 study subjects (61 severe and 12 moderate COVID-19) were included in this study. A total of 35 out of 61 severe and one out of 12 moderate illness subjects had experienced worsening. Spearman-rank correlation of IL-6 with with ferritin, D-dimer, fibrinogen, and PT was 0.08 ( p=0.5), -0.13 ( p=0.27), 0.01 ( p=0.91), and 0.03 ( p=0.77), respectively. In ROC analysis, D-dimer (74,77%) and IL-6 (71,32%) were the highest among other variables (>60%). Conclusions In COVID-19 patients, there was a correlation between elevated IL-6 and D-dimer levels with disease deterioration. There was no correlation between elevated IL-6 levels with ferritin, D-dimer, fibrinogen, and PT levels. Therefore, changes in IL-6 and D-dimer can predict worsening in moderate and severe COVID-19 patients.

Role of Mitochondria in the Regulation of Effector Functions of Granulocytes

Granulocytes (neutrophils, eosinophils, and basophils) are the most abundant circulating cells in the innate immune system. Circulating granulocytes, primarily neutrophils, can cross the endothelial barrier and activate various effector mechanisms to combat invasive pathogens. Eosinophils and basophils also play an important role in allergic reactions and antiparasitic defense. Granulocytes also regulate the immune response, wound healing, and tissue repair by releasing of various cytokines and lipid mediators. The effector mechanisms of granulocytes include the production of reactive oxygen species (ROS), degranulation, phagocytosis, and the formation of DNA-containing extracellular traps. Although all granulocytes are primarily glycolytic and have only a small number of mitochondria, a growing body of evidence suggests that mitochondria are involved in all effector functions as well as in the production of cytokines and lipid mediators and in apoptosis. It has been shown that the production of mitochondrial ROS controls signaling pathways that mediate the activation of granulocytes by various stimuli. In this review, we will briefly discuss the data on the role of mitochondria in the regulation of effector and other functions of granulocytes.

Phagocyte extracellular traps formation contributes to host defense against Clostridium perfringens infection

Clostridium perfringens (C. perfringens) is an important Gram-positive anaerobic spore-forming pathogen that provokes life-threatening gas gangrene and acute enterotoxaemia, although it colonizes as a component of the symbiotic bacteria in humans and animals. However, the mechanisms by which C. perfringens is cleared from the host remains poorly understood, thereby impeding the development of novel strategies for control this infection. Here, we uncover a beneficial effect of extracellular traps (ETs) formation on bacterial killing and clearance by phagocytes. C. perfringens strain ATCC13124, and wild-type isolates CP1 and CP3 markedly trigger ETs formation in macrophages and neutrophils. As expected, visualization of DNA decorated with histone, myeloperoxidase (MPO) and neutrophils elastase (NE) in C. perfringens-triggered classical ETs structures. Notably, the bacteria-induced ETs formation is an ERK1/2-, P38 MAPK-, store-operated calcium entry (SOCE)-, NADPH oxidase-, histone-, NE-, and MPO-dependent process, and is independent of LDH activity. Meanwhile, the defect of bactericidal activity is mediated by impairing ETs formation in phagocytes. Moreover, In vivo studies indicated that degradation of ETs by DNase I administration leads to a defect in the protection against experimental gas gangrene, with higher mortality rates, exacerbated tissue damage, and more bacterial colonization. Together, these results suggest that phagocyte ETs formation is essential for the host defense against C. perfringens infection.

Advanced hitchhiking nanomaterials for biomedical applications

Hitchhiking, a recently developed bio-inspired cargo delivery system, has been harnessed for diverse applications. By leveraging the interactions between nanoparticles and circulatory cells or proteins, hitchhiking enables efficient navigation through the vasculature while evading immune system clearance. Moreover, it allows for targeted delivery of nutrients to tissues, surveillance of the immune system, and pathogen elimination. Various synthetic nanomaterials have been developed to facilitate hitchhiking with circulatory cells or proteins. By combining the advantages of synthetic nanomaterials and circulatory cells or proteins, hitchhiking nanomaterials demonstrate several advantages over conventional vectors, including enhanced circulatory stability and optimized therapeutic efficacy. This review provides an overview of general strategies for hitchhiking, choices of cells and proteins, and recent advances of hitchhiking nanomaterials for biomedical applications.

Porphyromonas gingivalis Peptidyl Arginine Deiminase (PPAD) in the Context of the Feed-Forward Loop of Inflammation in Periodontitis

Periodontitis is a widespread chronic inflammatory disease caused by a changed dysbiotic oral microbiome. Although multiple species and risk factors are associated with periodontitis, Porphyromonas gingivalis has been identified as a keystone pathogen. The immune-modulatory function of P. gingivalis is well characterized, but the mechanism by which this bacterium secretes peptidyl arginine deiminase (PPAD), a protein/peptide citrullinating enzyme, thus contributing to the infinite feed-forward loop of inflammation, is not fully understood. To determine the functional role of citrullination in periodontitis, neutrophils were stimulated by P. gingivalis bearing wild-type PPAD and by a PPAD mutant strain lacking an active enzyme. Flow cytometry showed that PPAD contributed to prolonged neutrophil survival upon bacterial stimulation, accompanied by the secretion of aberrant IL-6 and TNF-α. To further assess the complex mechanism by which citrullination sustains a chronic inflammatory state, the ROS production and phagocytic activity of neutrophils were evaluated. Flow cytometry and colony formation assays showed that PPAD obstructs the resolution of inflammation by promoting neutrophil survival and the release of pro-inflammatory cytokines, while enhancing the resilience of the bacteria to phagocytosis.

Organic Matrix Derived from Host-Microbe Interplay Contributes to Pathological Renal Biomineralization

Matrix stones are a rare form of kidney stones. They feature a high percentage of hydrogel-like organic matter, and their formation is closely associated with urinary tract infections. Herein, comprehensive materials and biochemical approaches were taken to map the organic-inorganic interface and gather insights into the host-microbe interplay in pathological renal biomineralization. Surgically extracted soft and slimy matrix stones were examined using micro-X-ray computed tomography and various microspectroscopy techniques. Higher-mineral-density laminae were positive for calcium-bound Alizarin red. Lower-mineral-density laminae revealed periodic acid-Schiff-positive organic filamentous networks of varied thickness. These organic filamentous networks, which featured a high polysaccharide content, were enriched with zinc, carbon, and sulfur elements. Neutrophil extracellular traps (NETs) along with immune response-related proteins, including calprotectin, myeloperoxidase, CD63, and CD86, also were identified in the filamentous networks. Expressions of NETs and upregulation of polysaccharide-rich mucin secretion are proposed as a part of the host immune defense to "trap" pathogens. These host-microbe derived organic matrices can facilitate heterogeneous nucleation and precipitation of inorganic particulates, resulting in macroscale aggregates known as "matrix stones". These insights into the plausible aggregation of constituents through host-microbe interplay underscore the unique "double-edged sword" effect of the host immune response to pathogens and the resulting renal biominerals.

SARS-CoV-2 Spike Proteins and Cell-Cell Communication Induce P-Selectin and Markers of Endothelial Injury, NETosis, and Inflammation in Human Lung Microvascular Endothelial Cells and Neutrophils: Implications for the Pathogenesis of COVID-19 Coagulopathy

COVID-19 progression often involves severe lung injury, inflammation, coagulopathy, and leukocyte infiltration into pulmonary tissues. The pathogenesis of these complications is unknown. Because vascular endothelium and neutrophils express angiotensin-converting enzyme-2 and spike (S)-proteins, which are present in bodily fluids and tissues of SARS-CoV-2-infected patients, we investigated the effect of S-proteins and cell-cell communication on human lung microvascular endothelial cells and neutrophils expression of P-selectin, markers of coagulopathy, NETosis, and inflammation. Exposure of endothelial cells or neutrophils to S-proteins and endothelial-neutrophils co-culture induced P-selectin transcription and expression, significantly increased expression/secretion of IL-6, von Willebrand factor (vWF, pro-coagulant), and citrullinated histone H3 (cit-H3, NETosis marker). Compared to the SARS-CoV-2 Wuhan variant, Delta variant S-proteins induced 1.4-15-fold higher P-selectin and higher IL-6 and vWF. Recombinant tissue factor pathway inhibitor (rTFPI), 5,5'-dithio-bis-(2-nitrobenzoic acid) (thiol blocker), and thrombomodulin (anticoagulant) blocked S-protein-induced vWF, IL-6, and cit-H3. This suggests that following SARS-CoV-2 contact with the pulmonary endothelium or neutrophils and endothelial-neutrophil interactions, S-proteins increase adhesion molecules, induce endothelial injury, inflammation, NETosis and coagulopathy via the tissue factor pathway, mechanisms involving functional thiol groups, and/or the fibrinolysis system. Using rTFPI, effectors of the fibrinolysis system and/or thiol-based drugs could be viable therapeutic strategies against SARS-CoV-2-induced endothelial injury, inflammation, NETosis, and coagulopathy.

The Crossroads of the Coagulation System and the Immune System: Interactions and Connections

The coagulation and immune systems, two vital systems in the human body, share intimate connections that fundamentally determine patient health. These systems work together through several common regulatory pathways, including the Tissue Factor (TF) Pathway. Immune cells expressing TF and producing pro-inflammatory cytokines can influence coagulation, while coagulation factors and processes reciprocally impact immune responses by activating immune cells and controlling their functions. These shared pathways contribute to maintaining health and are also involved in various pathological conditions. Dysregulated coagulation, triggered by infection, inflammation, or tissue damage, can result in conditions such as disseminated intravascular coagulation (DIC). Concurrently, immune dysregulation may lead to coagulation disorders and thrombotic complications. This review elucidates these intricate interactions, emphasizing their roles in the pathogenesis of autoimmune diseases and cancer. Understanding the complex interplay between these systems is critical for disease management and the development of effective treatments. By exploring these common regulatory mechanisms, we can uncover innovative therapeutic strategies targeting these intricate disorders. Thus, this paper presents a comprehensive overview of the mutual interaction between the coagulation and immune systems, highlighting its significance in health maintenance and disease pathology.

Putative Role of Neutrophil Extracellular Trap Formation in Chronic Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPNs) are hematologic malignancies characterized by gene mutations that promote myeloproliferation and resistance to apoptosis via constitutively active signaling pathways, with Janus kinase 2-signal transducers and the activators of transcription (JAK-STAT) axis as a core part. Chronic inflammation has been described as a pivot for the development and advancement of MPNs from early stage cancer to pronounced bone marrow fibrosis, but there are still unresolved questions regarding this issue. The MPN neutrophils are characterized by upregulation of JAK target genes, they are in a state of activation and with deregulated apoptotic machinery. Deregulated neutrophil apoptotic cell death supports inflammation and steers them towards secondary necrosis or neutrophil extracellular trap (NET) formation, a trigger of inflammation both ways. NETs in proinflammatory bone marrow microenvironment induce hematopoietic precursor proliferation, which has an impact on hematopoietic disorders. In MPNs, neutrophils are primed for NET formation, and even though it seems obvious for NETs to intervene in the disease progression by supporting inflammation, no reliable data are available. We discuss in this review the potential pathophysiological relevance of NET formation in MPNs, with the intention of contributing to a better understanding of how neutrophils and neutrophil clonality can orchestrate the evolution of a pathological microenvironment in MPNs.

Plasma Gelsolin Enhances Phagocytosis of Candida auris by Human Neutrophils through Scavenger Receptor Class B

In addition to its role as an actin-depolymerizing factor in the blood, plasma gelsolin (pGSN) binds bacterial molecules and stimulates the phagocytosis of bacteria by macrophages. Here, using an in vitro system, we assessed whether pGSN could also stimulate phagocytosis of the fungal pathogen Candida auris by human neutrophils. The extraordinary ability of C. auris to evade immune responses makes it particularly challenging to eradicate in immunocompromised patients. We demonstrate that pGSN significantly enhances C. auris uptake and intracellular killing. Stimulation of phagocytosis was accompanied by decreased neutrophil extracellular trap (NET) formation and reduced secretion of proinflammatory cytokines. Gene expression studies revealed pGSN-dependent upregulation of scavenger receptor class B (SR-B). Inhibition of SR-B using sulfosuccinimidyl oleate (SSO) and block lipid transport-1 (BLT-1) decreased the ability of pGSN to enhance phagocytosis, indicating that pGSN potentiates the immune response through an SR-B-dependent pathway. These results suggest that the response of the host's immune system during C. auris infection may be enhanced by the administration of recombinant pGSN. IMPORTANCE The incidence of life-threatening multidrug-resistant Candida auris infections is rapidly growing, causing substantial economic costs due to outbreaks in hospital wards. Primary and secondary immunodeficiencies in susceptible individuals, such as those with leukemia, solid organ transplants, diabetes, and ongoing chemotherapy, often correlate with decreased plasma gelsolin concentration (hypogelsolinemia) and impairment of innate immune responses due to severe leukopenia. Immunocompromised patients are predisposed to superficial and invasive fungal infections. Morbidity caused by C. auris among immunocompromised patients can be as great as 60%. In the era of ever-growing fungal resistance in an aging society, it is critical to seek novel immunotherapies that may help combat these infections. The results reported here suggest the possibility of using pGSN as an immunomodulator of the immune response by neutrophils during C. auris infection.

Visualizing NETosis Using a Novel Neutrophil Extracellular Trap-Specific Marker

As the most abundant leukocyte in circulation, the neutrophil plays a far-reaching role in maintaining homeostasis. Within the context of disease, however, neutrophils can potentiate various pathophysiological mechanisms with disastrous consequences for patients. The role of the neutrophil in disease is complex with mechanisms like NETosis driving the progression of several pathologies. NETosis involves neutrophils extruding protein-decorated DNA webs called neutrophil extracellular traps (NETs), which facilitate the progression of inflammatory, non-infectious, and neoplastic pathologies. The need to visualize NETs has thus never been greater. Current approaches for visualizing NETs are limited in specificity and sensitivity, involving non-specific fluorescent DNA dyes or co-stains of neutrophil and DNA markers. Improved methodologies are needed to robustly distinguish NETs from other cell-free DNA. Excitingly, a novel NET-specific posttranslational modification involving cleavage on the N-terminus of histone H3 has recently been identified. Here, we demonstrate that this single marker is superior to the conventional use of the co-stain of the neutrophil marker, myeloperoxidase, and, the DNA marker, histone H3 citrullination in visualizing neutrophil NETosis. This is due to this single marker's unparalleled ability to identify, not only more NETs but also their formation at earlier stages of NETosis. Moreover, we additionally propose a stepwise mechanism of neutrophil NETosis in which a histone H3 cleavage event precedes histone H3 citrullination. Taken together, these results demonstrate a novel method for visualizing NETs, allowing for continued exploration of their multifaceted roles in immunity and disease.

The role of neutrophil extracellular traps in cancer progression, metastasis and therapy

Neutrophil extracellular traps (NETs) released by activated neutrophils typically consist of DNA-histone complexes and granule proteins. NETs were originally identified as a host defense system against foreign pathogens and are strongly associated with autoimmune diseases. However, a novel and predominant role of NETs in cancer is emerging. Increasing evidence has confirmed that many stimuli can facilitate NET formation in an NADPH oxidase (NOX)-dependent/NOX-independent manner. In cancer, NETs have been linked to cancer progression, metastasis, and cancer-associated thrombosis. In this review, we aimed to summarize the current available knowledge regarding NET formation and focused on the role of NETs in cancer biological behaviors. The potential target for cancer therapy will be further discussed.

The molecular mechanisms underlying neutrophil infiltration in vessel co-opting colorectal cancer liver metastases

Colorectal cancer liver metastases (CRCLMs) have two major histopathological growth patterns (HGPs): desmoplastic (DHGP) and replacement (RHGP). The DHGP tumours derive their vasculature by angiogenesis, while the RHGP tumours use vessel co-option. Various studies have associated RHGP tumours with an unfavourable prognosis, as well as high levels of resistance to anti-angiogenic agents and chemotherapy. Recently, we reported higher numbers of neutrophils in the tumour microenvironment (TME) of vessel co-opting tumours compared to their angiogenic counterparts. However, the molecular mechanisms underlying this phenotype are unclear. Herein, we suggested a positive correlation between the expression of angiopoietin-1 (Ang1) in the hepatocytes and the presence of neutrophils in vessel co-opting tumours. Importantly, upregulation of Ang1 in the hepatocytes is associated with the presence of runt-related transcription factor-1 (RUNX1) in the neighboring cancer cells in vitro and in vivo. Altogether, our data suggest the molecular mechanisms by which neutrophils are infiltrated in vessel co-opting CRCLM lesions. This finding may yield novel therapeutic strategies for CRCLM patients in future.

Practical Significance of Biomarkers in Axial Spondyloarthritis: Updates on Diagnosis, Disease Activity, and Prognosis

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease that can lead to ankylosis by secondary ossification of inflammatory lesions, with progressive disability and a significant impact on quality of life. It is also a risk factor for the occurrence of comorbidities, especially cardiovascular diseases (CVDs), mood disorders, osteoporosis, and malignancies. Early diagnosis and treatment are needed to prevent or decrease functional decline and to improve the patient's prognosis. In respect of axSpA, there is an unmet need for biomarkers that can help to diagnose the disease, define disease activity and prognosis, and establish personalized treatment approaches. The aim of this review was to summarize the available information regarding the most promising biomarkers for axSpA. We classified and identified six core categories of biomarkers: (i) systemic markers of inflammation; (ii) molecules involved in bone homeostasis; (iii) HLA-B27 and newer genetic biomarkers; (iv) antibody-based biomarkers; (v) microbiome biomarkers; and (vi) miscellaneous biomarkers. Unfortunately, despite efforts to validate new biomarkers, few of them are used in clinical practice; however, we believe that these studies provide useful data that could aid in better disease management.

Association between chronic obstructive pulmonary disease and periodontitis: The common role of innate immune cells?

Innate immune cells are of broad interest in a variety of diseases. These cells include neutrophils, macrophages, dendritic cells and mast cells, etc. Innate immune cells are often mentioned in inflammatory diseases as the first line of defense against pathogens' invasion. As chronic obstructive pulmonary disease and periodontitis are inflammatory diseases, innate immune cells play an important role in the development of both diseases. COPD and periodontitis are common epidemic diseases with a very high prevalence, thus affecting a large number of people and also reducing the quality of life of patients. In addition, epidemiological studies suggested a link between the two, creating a co-morbid burden, but the mechanism of the link is yet to be explained. This article discusses the possible mechanism of the link between the two diseases in terms of innate immune cells and discusses possible future targeted therapies that could alleviate the burden on patients.

Activated Platelets and Platelet-Derived Extracellular Vesicles Mediate COVID-19-Associated Immunothrombosis

Activated platelets and platelet-derived extracellular vesicles (EVs) have emerged as central players in thromboembolic complications associated with severe coronavirus disease 2019 (COVID-19). Platelets bridge hemostatic, inflammatory, and immune responses by their ability to sense pathogens via various pattern recognition receptors, and they respond to infection through a diverse repertoire of mechanisms. Dysregulated platelet activation, however, can lead to immunothrombosis, a simultaneous overactivation of blood coagulation and the innate immune response. Mediators released by activated platelets in response to infection, such as antimicrobial peptides, high mobility group box 1 protein, platelet factor 4 (PF4), and PF4⁺ extracellular vesicles promote neutrophil activation, resulting in the release of neutrophil extracellular traps and histones. Many of the factors released during platelet and neutrophil activation are positively charged and interact with endogenous heparan sulfate or exogenously administered heparin via electrostatic interactions or via specific binding sites. Here, we review the current state of knowledge regarding the involvement of platelets and platelet-derived EVs in the pathogenesis of immunothrombosis, and we discuss the potential of extracorporeal therapies using adsorbents functionalized with heparin to deplete platelet-derived and neutrophil-derived mediators of immunothrombosis.

The association between diabetes and obesity with Dengue infections

Dengue, an arboviral disease is a global threat to public health as the number of Dengue cases increases through the decades and this trend is predicted to continue. Non-communicable diseases such as diabetes and obesity are also on an upward trend. Moreover, past clinical studies have shown comorbidities worsen the clinical manifestation of especially Severe Dengue. However, discussion regarding the underlying mechanisms regarding the association between these comorbidities and dengue are lacking. The hallmark of Severe Dengue is plasma leakage which is due to several factors including presence of pro-inflammatory cytokines and dysregulation of endothelial barrier protein expression. The key factors of diabetes affecting endothelial functions are Th1 skewed responses and junctional-related proteins expression. Additionally, obesity alters the lipid metabolism and immune response causing increased viral replication and inflammation. The similarity between diabetes and obesity individuals is in having chronic inflammation resulting in endothelial dysfunction. This review outlines the roles of diabetes and obesity in severe dengue and gives some insights into the plausible mechanisms of comorbidities in Severe Dengue.

Friend or Foe: The Relativity of (Anti)oxidative Agents and Pathways

An element, iron, a process, the generation of reactive oxygen species (ROS), and a molecule, ascorbate, were chosen in our study to show their dual functions and their role in cell fate decision. Iron is a critical component of numerous proteins involved in metabolism and detoxification. On the other hand, excessive amounts of free iron in the presence of oxygen can promote the production of potentially toxic ROS. They can result in persistent oxidative stress, which in turn can lead to damage and cell death. At the same time, ROS—at strictly regulated levels—are essential to maintaining the redox homeostasis, and they are engaged in many cellular signaling pathways, so their total elimination is not expedient. Ascorbate establishes a special link between ROS generation/elimination and cell death. At low concentrations, it behaves as an excellent antioxidant and has an important role in ROS elimination. However, at high concentrations, in the presence of transition metals such as iron, it drives the generation of ROS. In the term of the dual function of these molecules and oxidative stress, ascorbate/ROS-driven cell deaths are not necessarily harmful processes—they can be live-savers too.

In Vitro Production of Neutrophils Extracellular Traps Is Affected by the Lactational Stage of Dairy Cows

We aimed to research the neutrophil extracellular traps (NETs) and reactive oxygen species (ROS) formation capacity of polymorphonuclear cells (PMN) during different lactational stages of Holstein cows. We also aimed to validate a model which could mimic infection and inflammation in vitro by adding increasing concentrations of lipopolysaccharide (LPS) and phorbol 12-myristate 13-acetate (PMA) to PMN suspensions isolated from nulliparous heifers and evaluate their capacity to produce NETs and ROS. In 3 replicates, we collected blood from nulliparous heifers (n = 3), cows at the end of gestation (n = 3), early postpartum (n = 3) and in mid-lactation (n = 3) in which PMN were isolated. The production of ROS in PMN were assessed using the 2’,7’-Dichlorofluorescein diacetate method, while the SYTOX Orange and Quant-iT™ PicoGreen dsDNA ultra-sensitive nucleic fluorescent acid staining methods were applied in order to quantitatively analyze the formation of NETs. Statistical analyses were performed via linear regression models using the replicate as a random. ROS values of PMN harvested from peripartum cows were 1.3 times increased compared with those in nulliparous heifers (p < 0.01). Compared with nulliparous heifers, the production of NETs by PMN isolated from mid-lactation and postpartum cows was 2.1 and 2.5 times higher (p < 0.01), respectively. In 3 replicates, in vitro stimulation of PMN isolated from nulliparous heifers (n = 3) with LPS linearly increased the production of ROS and NETs (R2 = 0.96 and 0.86, respectively). Similarly, when PMN isolated from nulliparous heifers were stimulated with PMA, a linear increase in the production of ROS (R2 = 0.99) and NETs (R2 = 0.78) was observed. The basal NETs and ROS production is lower in nulliparous heifers. Thus, they are an excellent model to mimic inflammation and study fundamental aspects of the production of NETs and ROS in vitro.

A Neutrophil Extracellular Traps Signature Predicts the Clinical Outcomes and Immunotherapy Response in Head and Neck Squamous Cell Carcinoma

Background: Neutrophil extracellular traps (NETs) play an important role in the occurrence, metastasis and immune escape of cancers. This study aimed to investigate NET-related genes, their clinical prognostic value and their correlation with immunotherapy and anticancer drugs in patients with head and neck squamous cell carcinoma (HNSCC).

Methods: Differentially expressed NET-related genes in HNSCC were identified based on multiple public databases. To improve the clinical practicability and avoid overfitting, univariable, least absolute shrinkage and selection operator (LASSO) and multivariable Cox algorithms were used to construct a prognostic risk model. A nomogram was further used to explore the clinical value of the model. Internal and external validation were conducted to test the model. Furthermore, the immune microenvironment, immunophenoscore (IPS) and sensitivity to anticancer drugs in HNSCC patients with different prognostic risks were explored.

Results: Six NET-related genes were screened to construct the risk model. In the training cohort, Kaplan–Meier (K-M) analysis showed that the overall survival (OS) of low-risk HNSCC patients was significantly better than that of high-risk HNSCC patients (p < 0.001). The nomogram also showed a promising prognostic value with a better C-index (0.726 vs 0.640) and area under the curve (AUC) (0.743 vs 0.706 at 3 years, 0.743 vs 0.645 at 5 years) than those in previous studies. Calibration plots and decision curve analysis (DCA) also showed the satisfactory predictive capacity of the nomogram. Internal and external validation further strengthened the credibility of the clinical prognostic model. The level of tumor mutational burden (TMB) in the high-risk group was significantly higher than that in the low-risk group (p = 0.017), and the TMB was positively correlated with the risk score (R = 0.11; p = 0.019). Moreover, the difference in immune infiltration was significant in HNSCC patients with different risks (p < 0.05). Furthermore, the IPS analysis indicated that anti-PD-1 (p < 0.001), anti-CTLA4 (p < 0.001) or combining immunotherapies (p < 0.001) were more beneficial for low-risk HNSCC patients. The response to anticancer drugs was also closely correlated with the expression of NET-related genes (p < 0.001).

Conclusion: This study identified a novel prognostic model that might be beneficial to develop personalized treatment for HNSCC patients.

Clinical Value of Prognostic Nutritional Index in Prediction of the Presence and Severity of Neonatal Sepsis

Purpose

The prognostic nutritional index (PNI) is a common indicator of nutritional and inflammatory status and is associated with various diseases such as cancer, cardiovascular diseases and infectious diseases. However, to date, no study has concentrated on the role of PNI in assessing and predicting the presence and severity of neonatal sepsis. Therefore, the present study aimed to explore the association of the PNI with the presence and severity of neonatal sepsis.

Materials and Methods

A total of 1196 neonates with suspected sepsis were enrolled in this study and their complete clinical and laboratory data were collected. PNI was calculated as serum albumin (g/L) + 5 × total lymphocyte count (10⁹/L). Multivariate logistic regression analysis was performed to identify the risk factors for the presence and severity of neonatal sepsis. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the predictive value of PNI. All statistical analyses were performed using the statistical package SPSS 24.0.

Results

PNI was lower in neonates with sepsis and decreased significantly with the severity of sepsis. The correlation analysis demonstrated that the PNI was negatively correlated with the levels of the inflammatory marker procalcitonin (PCT) and C-reactive protein (CRP), and the length of hospital stay. Multivariate logistic regression analysis revealed that the PNI was independently and inversely associated with the presence and severity of neonatal sepsis. The area under the ROC curve of the PNI was 0.64 (95% confidence interval (CI): 0.61–0.67, P < 0.001) for severe sepsis and 0.69 (95% CI: 0.60–0.78, P < 0.001) for septic shock. In addition, our data revealed that PNI was also independently correlated with the length of hospital stay.

Conclusion

PNI is an independent predictor for the presence and severity of neonatal sepsis.

The Emerging Role of Neutrophil Extracellular Traps in Arterial, Venous and Cancer-Associated Thrombosis

Neutrophils play a vital role in the formation of arterial, venous and cancer-related thrombosis. Recent studies have shown that in a process known as NETosis, neutrophils release proteins and enzymes complexed to DNA fibers, collectively called neutrophil extracellular traps (NETs). Although NETs were originally described as a way for the host to capture and kill bacteria, current knowledge indicates that NETs also play an important role in thrombosis. According to recent studies, the destruction of vascular microenvironmental homeostasis and excessive NET formation lead to pathological thrombosis. In vitro experiments have found that NETs provide skeletal support for platelets, red blood cells and procoagulant molecules to promote thrombosis. The protein components contained in NETs activate the endogenous coagulation pathway to promote thrombosis. Therefore, NETs play an important role in the formation of arterial thrombosis, venous thrombosis and cancer-related thrombosis. This review will systematically summarize and explain the study of NETs in thrombosis in animal models and in vivo experiments to provide new targets for thrombosis prevention and treatment.

Higher blood urea nitrogen level is independently linked with the presence and severity of neonatal sepsis

BACKGROUND

Previous studies have demonstrated that blood urea nitrogen (BUN) is strongly associated with sepsis. However, no data are currently available regarding the association of BUN levels and neonatal sepsis. Thus, this study aimed to investigate the role of BUN in predicting the presence and severity of neonatal sepsis.

METHODS

In this study, we enrolled 925 neonates. Among them, 737 neonates were diagnosed with sepsis, including 426 neonates with severe sepsis. Neonates with hyperbilirubinemia (n = 188) served as controls. We collected complete clinical and laboratory data were collected. Multivariate logistic regression analysis was performed to identify the potential independent risk factor for neonatal sepsis. Receiver operating characteristic (ROC) curve analysis was used to evaluate the prediction accuracy of BUN in predicting neonatal sepsis. All statistical analyses were performed using the statistical package SPSS 24.0.

RESULTS

Neonates with sepsis and severe sepsis had a higher level of BUN. The prevalence of neonates with severe sepsis was dramatically increased according to BUN tertiles. Correlation analysis showed that BUN levels were positively correlated with the levels of infection marker procalcitonin (PCT) and high-sensitivity C-reactive protein (hsCRP). Multiple logistic regression analysis showed that BUN was an independent risk factor for the presence and severity of neonatal sepsis. ROC curve analysis showed that BUN had a well discriminatory power in predicting sepsis (area under curve (AUC) = 0.69, 95% CI, 0.66-0.74, p < .001) and severe sepsis (AUC = 0.72, 95% CI, 0.67-0.78, p < .001).

CONCLUSION

Higher BUN level is independently linked with the presence and severity of neonatal sepsis.

Clinical Value of C-Reactive Protein/Platelet Ratio in Neonatal Sepsis: A Cross-Sectional Study

Purpose

C-reactive protein (CRP) level and platelet (PLT) count have been demonstrated to be independent risk factor for neonatal sepsis. However, no data is currently available in regarding the association between CRP-to-PLT ratio (CPR) and neonatal sepsis.

Methods

A total of 1048 neonates with suspected sepsis were enrolled in this study. Complete clinical and laboratory data were collected. CPR was calculated as CRP (mg/L)/PLT (10⁷ cells/L). Multivariate logistic regression analysis was performed to identify the potential independent risk factors of neonatal sepsis. Receiver operating characteristic (ROC) curve analysis was used to evaluate the prediction accuracy of CPR in predicting neonatal sepsis.

Results

Neonates with sepsis had a higher CPR. CPR also showed a gradual increase in the infection, mild sepsis and severe sepsis groups. Multivariate analysis revealed that CPR was a significant independent predictor of the presence of neonatal sepsis (odds ratio [OR], 1.015; 95% confidence interval [CI], 1.008-1.022, P < 0.001) and severe sepsis (OR, 1.002; 95% CI, 1.000-1.003, P = 0.007). ROC curve revealed showed that CPR had a well-discriminatory power in predicting sepsis (area under curve [AUC], 0.68; 95% CI, 0.65-0.72, P < 0.001) and severe sepsis (AUC, 0.68; 95% CI, 0.65-0.72, P < 0.001).

Conclusion

The present study demonstrated that a higher CPR is an independent predictor of the presence and severity of neonatal sepsis.

Uncovering the Oral Dysbiotic Microbiota as Masters of Neutrophil Responses in the Pathobiology of Periodontitis

Numerous bacterial species participate in the shift of the oral microbiome from beneficial to dysbiotic. The biggest challenge lying ahead of microbiologists, immunologists and dentists is the fact that the bacterial species act differently, although usually synergistically, on the host immune cells, including neutrophils, and on the surrounding tissues, making the investigation of single factors challenging. As biofilm is a complex community, the members interact with each other, which can be a key issue in future studies designed to develop effective treatments. To understand how a patient gets to the stage of the late-onset (previously termed chronic) periodontitis or develops other, in some cases life-threatening, diseases, it is crucial to identify the microbial composition of the biofilm and the mechanisms behind its pathogenicity. The members of the red complex (Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia) have long been associated as the cause of periodontitis and stayed in the focus of research. However, novel techniques, such as 16S clonal analysis, demonstrated that the oral microbiome diversity is greater than ever expected and it opened a new era in periodontal research. This review aims to summarize the current knowledge concerning bacterial participation beyond P. gingivalis and the red complex in periodontal inflammation mediated by neutrophils and to spread awareness about the associated diseases and pathological conditions.

The FcγRIII Engagement Augments PMA-Stimulated Neutrophil Extracellular Traps (NETs) Formation by Granulocytes Partially via Cross-Talk between Syk-ERK-NF-κB and PKC-ROS Signaling Pathways

Polymorphonuclear neutrophils (PMNs) are the most abundant white blood cell in the circulation capable of neutrophil extracellular traps (NETs) formation after stimulation. Both NADPH oxidase-dependent and -independent pathways are involved in NET formation. The IgG is the most abundant immunoglobulin in human serum. However, the impact of the circulating IgG on NET formation is totally unexplored. In this study, the all-trans retinoic acid (ATRA)-induced mature granulocytes (dHL-60) were pre-treated with monomeric human IgG, papain-digested Fab fragment, crystallizable IgG Fc portion, rituximab (a human IgG1), or IgG2. The NET formation of the dHL-60 in the presence/absence of phorbol 12-myristate 13-acetate (PMA) stimulation was then measured by the fluorescent area after SYTOX green nucleic acid stain. The intracellular reactive oxygen species (ROS) generation was measured by flow cytometry. Total and phosphorylated Syk, SHP-1, and ERK were detected by immunoblot. We found that human monomeric IgG and its subclasses IgG1 and IgG2 per se induced negligible NET formation of dHL-60, but the FcγRIII engagement by these IgG subclasses and Fc portion augment PMA-stimulated dHL-60 NET formation in a dose-dependent manner. Furthermore, we found that increased Syk and ERK phosphorylation, intracellular ROS generation, and pro-inflammatory cytokines, IL-8 and TNF-α, production could be induced after FcγRIII engagement. Blocking FcγRIII engagement by a specific antibody diminished the augmented NET formation. In conclusion, we discovered that cross-talk between FcγRIII engagement-induced Syk-ERK and PMA-induced PKC signaling pathways augment NET formation of dHL-60 via increased ROS generation and pro-inflammatory cytokines, IL-8 and TNF-α, production.

Analysis of Gene Expression Profiles, Cytokines, and Bacterial Loads Relevant to Alcoholic Liver Disease Mice Infected With V. vulnificus

Patients with liver disease are susceptible to infection with Vibrio vulnificus (V. vulnificus), but the specific reasons remain elusive. Through RNA-seq, we found that when mice with alcoholic liver disease (ALD) were infected with V. vulnificus by gavage, compared with the Pair group, the small intestinal genes affecting intestinal permeability were upregulated; and the number of differentially expressed genes related to immune functions (e.g., such as cell chemotaxis, leukocyte differentiation, and neutrophil degranulation) decreased in the liver, spleen, and blood. Further analysis showed that the number of white blood cells decreased in the Pair group, whereas those in the ALD mice did not change significantly. Interestingly, the blood bacterial load in the ALD mice was about 100 times higher than that of the Pair group. After the ALD mice were infected with V. vulnificus, the concentrations of T cell proliferation-promoting cytokines (IL-2, IL-23) decreased. Therefore, unlike the Pair group, ALD mice had weaker immune responses, lower T cell proliferation-promoting cytokines, and higher bacterial loads post-infection, possibly increasing their susceptibility to V. vulnificus infection. These new findings we presented here may help to advance the current understanding of the reasons why patients with liver disease are susceptible to V. vulnificus infection and provides potential targets for further investigation in the context of treatment options for V. vulnificus sepsis in liver disease patient.

Contemporary Lifestyle and Neutrophil Extracellular Traps: An Emerging Link in Atherosclerosis Disease

Neutrophil extracellular traps (NETs) are networks of extracellular genetic material decorated with proteins of nuclear, granular and cytosolic origin that activated neutrophils expel under pathogenic inflammatory conditions. NETs are part of the host's innate immune defense system against invading pathogens. Interestingly, these extracellular structures can also be released in response to sterile inflammatory stimuli (e.g., shear stress, lipidic molecules, pro-thrombotic factors, aggregated platelets, or pro-inflammatory cytokines), as in atherosclerosis disease. Indeed, NETs have been identified in the intimal surface of diseased arteries under cardiovascular disease conditions, where they sustain inflammation via NET-mediated cell-adhesion mechanisms and promote cellular dysfunction and tissue damage via NET-associated cytotoxicity. This review will focus on (1) the active role of neutrophils and NETs as underestimated players of the inflammatory process during atherogenesis and lesion progression; (2) how these extracellular structures communicate with the main cell types present in the atherosclerotic lesion in the arterial wall; and (3) how these neutrophil effector functions interplay with lifestyle-derived risk factors such as an unbalanced diet, physical inactivity, smoking or lack of sleep quality, which represent major elements in the development of cardiovascular disease.

The association between circulating neutrophil extracellular trap related biomarkers and retinal vein occlusion incidence: A case-control pilot study

Retinal vein occlusion (RVO) is the second most common retinal vascular disorders and causes visual damage in a large population. Neutrophil extracellular traps (NETs) formation (NETosis) is an important cause of vascular diseases, however, the association between NETs related biomarkers and RVO development remained unclear. In this pilot study, a total of 77 RVO cases and 48 controls were included between Jan 2020 and July 2020. Besides, the circulating levels of three NETs related markers, cell-free DNA (cfDNA), myeloperoxidase (MPO)-DNA and citrullinated histone H3 (H3Cit), were detected in all the participants and thus the association between NETosis and RVO incidence was analyzed. Advanced assays were conducted to investigate the inflammation and thrombosis related biomarkers in RVO cases with higher or lower NETs biomarkers. When the results were considered, it was found that NETs biomarkers, including cfDNA, MPO-DNA and H3Cit, were increased in the RVO cases comparing with the controls (P < 0.05). Through the receiver operating characteristic (ROC) analyses, we found that circulating NETs related biomarkers demonstrated potential diagnostic effects for RVO and the AUCs of plasma cfDNA, MPO-DNA and H3Cit were 0.859, 0.871 and 0.928, respectively (P < 0.001). Through analyzing the correlations between circulating NETs markers and RVO stages and durations, inflammatory markers as well as thrombotic indexes, it was found that NETs were related with the RVO subtypes, inflammatory status and thrombus formation. In conclusion, the plasma NETs remnants are significantly increased in RVO cases. Besides, advanced studies demonstrate that inflammation as well as thrombus formation might be involved in this association.

Review of the potential of mesenchymal stem cells for the treatment of infectious diseases

The therapeutic value of mesenchymal stem cells (MSCs) for the treatment of infectious diseases and the repair of disease-induced tissue damage has been explored extensively. MSCs inhibit inflammation, reduce pathogen load and tissue damage encountered during infectious diseases through the secretion of antimicrobial factors for pathogen clearance and they phagocytose certain bacteria themselves. MSCs dampen tissue damage during infection by downregulating the levels of pro-inflammatory cytokines, and inhibiting the excessive recruitment of neutrophils and proliferation of T cells at the site of injury. MSCs aid in the regeneration of damaged tissue by differentiating into the damaged cell types or by releasing paracrine factors that direct tissue regeneration, differentiation, and wound healing. In this review, we discuss in detail the various mechanisms by which MSCs help combat pathogens, tissue damage associated with infectious diseases, and challenges in utilizing MSCs for therapy.

Acinetobacter baumannii: An Ancient Commensal with Weapons of a Pathogen

Acinetobacter baumannii is regarded as a life-threatening pathogen associated with community-acquired and nosocomial infections, mainly pneumonia. The rise in the number of A. baumannii antibiotic-resistant strains reduces effective therapies and increases mortality. Bacterial comparative genomic studies have unraveled the innate and acquired virulence factors of A. baumannii. These virulence factors are involved in antibiotic resistance, environmental persistence, host-pathogen interactions, and immune evasion. Studies on host–pathogen interactions revealed that A. baumannii evolved different mechanisms to adhere to in order to invade host respiratory cells as well as evade the host immune system. In this review, we discuss current data on A. baumannii genetic features and virulence factors. An emphasis is given to the players in host–pathogen interaction in the respiratory tract. In addition, we report recent investigations into host defense systems using in vitro and in vivo models, providing new insights into the innate immune response to A. baumannii infections. Increasing our knowledge of A. baumannii pathogenesis may help the development of novel therapeutic strategies based on anti-adhesive, anti-virulence, and anti-cell to cell signaling pathways drugs.

The Role of Neutrophil Extracellular Traps in Periodontitis

Periodontitis is a chronic, destructive disease of periodontal tissues caused by multifaceted, dynamic interactions. Periodontal bacteria and host immunity jointly contribute to the pathological processes of the disease. The dysbiotic microbial communities elicit an excessive immune response, mainly by polymorphonuclear neutrophils (PMNs). As one of the main mechanisms of PMN immune response in the oral cavity, neutrophil extracellular traps (NETs) play a crucial role in the initiation and progression of late-onset periodontitis. NETs are generated and released by neutrophils stimulated by various irritants, such as pathogens, host-derived mediators, and drugs. Chromatin and proteins are the main components of NETs. Depending on the characteristics of the processes, three main pathways of NET formation have been described. NETs can trap and kill pathogens by increased expression of antibacterial components and identifying and trapping bacteria to restrict their spread. Moreover, NETs can promote and reduce inflammation, inflicting injuries on the tissues during the pro-inflammation process. During their long-term encounter with NETs, periodontal bacteria have developed various mechanisms, including breaking down DNA of NETs, degrading antibacterial proteins, and impacting NET levels in the pocket environment to resist the antibacterial function of NETs. In addition, periodontal pathogens can secrete pro-inflammatory factors to perpetuate the inflammatory environment and a friendly growth environment, which are responsible for the progressive tissue damage. By learning the strategies of pathogens, regulating the periodontal concentration of NETs becomes possible. Some practical ways to treat late-onset periodontitis are reducing the concentration of NETs, administering anti-inflammatory therapy, and prescribing broad-spectrum and specific antibacterial agents. This review mainly focuses on the mechanism of NETs, pathogenesis of periodontitis, and potential therapeutic approaches based on interactions between NETs and periodontal pathogens.

The Pathogenesis of Aspergillus fumigatus, Host Defense Mechanisms, and the Development of AFMP4 Antigen as a Vaccine

Aspergillus fumigatus is one of the ubiquitous fungi with airborne conidia, which accounts for most aspergillosis cases. In immunocompetent hosts, the inhaled conidia are rapidly eliminated. However, immunocompromised or immunodeficient hosts are particularly vulnerable to most Aspergillus infections and invasive aspergillosis (IA), with mortality from 50% to 95%. Despite the improvement of antifungal drugs over the last few decades, the therapeutic effect for IA patients is still limited and does not provide significant survival benefits. The drawbacks of antifungal drugs such as side effects, antifungal drug resistance, and the high cost of antifungal drugs highlight the importance of finding novel therapeutic and preventive approaches to fight against IA. In this article, we systemically addressed the pathogenic mechanisms, defense mechanisms against A. fumigatus, the immune response, molecular aspects of host evasion, and vaccines' current development against aspergillosis, particularly those based on AFMP4 protein, which might be a promising antigen for the development of anti-A. fumigatus vaccines.

Role of Neutrophils in the Pathogenesis of Nonalcoholic Steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) includes a spectrum of liver disorders, from fatty liver to nonalcoholic steatohepatitis (NASH), cirrhosis, and hepatocellular carcinoma. Compared with fatty liver, NASH is characterized by increased liver injury and inflammation, in which liver-infiltrating immune cells, with neutrophil infiltration as a hallmark of NASH, play a critical role in promoting the progression of fatty liver to NASH. Neutrophils are the first responders to injury and infection in various tissues, establishing the first line of defense through multiple mechanisms such as phagocytosis, cytokine secretion, reactive oxygen species production, and neutrophil extracellular trap formation; however, their roles in the pathogenesis of NASH remain obscure. The current review summarizes the roles of neutrophils that facilitate the progression of fatty liver to NASH and their involvement in inflammation resolution during NASH pathogenesis. The notion that neutrophils are potential therapeutic targets for the treatment of NASH is also discussed.

Association of Neutrophil-Lymphocyte Ratio and the Presence of Neonatal Sepsis

The neutrophil–lymphocyte ratio (NLR) is an emerging risk factor of sepsis that is receiving increasing attention. However, the relationship between NLR and the presence of sepsis in neonates is poorly studied. Here, we retrospectively recruited 1480 neonates and collected and analyzed relevant clinical and laboratory data. According to the International Pediatric Sepsis Consensus, 737 neonates were diagnosed with sepsis, and 555 neonates were suspected for having infection. Neonates with hyperbilirubinemia (n = 188) served as controls. Neonates with sepsis had significantly elevated neutrophil counts and NLR (P < 0.001). The proportion of neonates with sepsis increased significantly from 41.6% when NLR < 0.91 to 66.2% when NLR > 1.88 group (P < 0.001). Multiple logistic regression analysis showed that NLR was an independent risk factor for the presence of neonatal sepsis. Receiver operating characteristic (ROC) curve analysis showed that the optimal cut-off value NLR for predicting the presence of neonatal sepsis was 1.62 (area under curve (AUC) = 0.63, 95% CI 0.60–0.66, P < 0.001). In conclusion, our data suggest that elevated NLR levels are associated with a higher neonatal sepsis risk.

TLR9 in MAFLD and NASH: At the Intersection of Inflammation and Metabolism

Toll-Like Receptor 9 (TLR9) is an ancient receptor integral to the primordial functions of inflammation and metabolism. TLR9 functions to regulate homeostasis in a healthy system under acute stress. The literature supports that overactivation of TLR9 under the chronic stress of obesity is a critical driver of the pathogenesis of NASH and NASH-associated fibrosis. Research has focused on the core contributions of the parenchymal and non-parenchymal cells in the liver, adipose, and gut compartments. TLR9 is activated by endogenous circulating mitochondrial DNA (mtDNA). Chronically elevated circulating levels of mtDNA, caused by the stress of overnutrition, are observed in obesity, metabolic dysfunction-associated fatty liver disease (MAFLD), and NASH. Clinical evidence is supportive of TLR9 overactivation as a driver of disease. The role of TLR9 in metabolism and energy regulation may have an underappreciated contribution in the pathogenesis of NASH. Antagonism of TLR9 in NASH and NASH-associated fibrosis could be an effective therapeutic strategy to target both the inflammatory and metabolic components of such a complex disease.