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1.
Cells ; 11(5)2022 03 01.
Article in English | MEDLINE | ID: covidwho-1715131

ABSTRACT

Severe COVID-19 patients present a clinical and laboratory overlap with other hyperinflammatory conditions such as hemophagocytic lymphohistiocytosis (HLH). However, the underlying mechanisms of these conditions remain to be explored. Here, we investigated the transcriptome of 1596 individuals, including patients with COVID-19 in comparison to healthy controls, other acute inflammatory states (HLH, multisystem inflammatory syndrome in children [MIS-C], Kawasaki disease [KD]), and different respiratory infections (seasonal coronavirus, influenza, bacterial pneumonia). We observed that COVID-19 and HLH share immunological pathways (cytokine/chemokine signaling and neutrophil-mediated immune responses), including gene signatures that stratify COVID-19 patients admitted to the intensive care unit (ICU) and COVID-19_nonICU patients. Of note, among the common differentially expressed genes (DEG), there is a cluster of neutrophil-associated genes that reflects a generalized hyperinflammatory state since it is also dysregulated in patients with KD and bacterial pneumonia. These genes are dysregulated at the protein level across several COVID-19 studies and form an interconnected network with differentially expressed plasma proteins that point to neutrophil hyperactivation in COVID-19 patients admitted to the intensive care unit. scRNAseq analysis indicated that these genes are specifically upregulated across different leukocyte populations, including lymphocyte subsets and immature neutrophils. Artificial intelligence modeling confirmed the strong association of these genes with COVID-19 severity. Thus, our work indicates putative therapeutic pathways for intervention.


Subject(s)
COVID-19 , Lymphohistiocytosis, Hemophagocytic , Artificial Intelligence , COVID-19/complications , COVID-19/genetics , Child , Humans , Lymphohistiocytosis, Hemophagocytic/complications , Neutrophil Activation , SARS-CoV-2 , Systemic Inflammatory Response Syndrome
2.
JCI Insight ; 7(7)2022 Apr 08.
Article in English | MEDLINE | ID: covidwho-1691177

ABSTRACT

Studying temporal gene expression shifts during disease progression provides important insights into the biological mechanisms that distinguish adaptive and maladaptive responses. Existing tools for the analysis of time course transcriptomic data are not designed to optimally identify distinct temporal patterns when analyzing dynamic differentially expressed genes (DDEGs). Moreover, there are not enough methods to assess and visualize the temporal progression of biological pathways mapped from time course transcriptomic data sets. In this study, we developed an open-source R package TrendCatcher (https://github.com/jaleesr/TrendCatcher), which applies the smoothing spline ANOVA model and break point searching strategy, to identify and visualize distinct dynamic transcriptional gene signatures and biological processes from longitudinal data sets. We used TrendCatcher to perform a systematic temporal analysis of COVID-19 peripheral blood transcriptomes, including bulk and single-cell RNA-Seq time course data. TrendCatcher uncovered the early and persistent activation of neutrophils and coagulation pathways, as well as impaired type I IFN (IFN-I) signaling in circulating cells as a hallmark of patients who progressed to severe COVID-19, whereas no such patterns were identified in individuals receiving SARS-CoV-2 vaccinations or patients with mild COVID-19. These results underscore the importance of systematic temporal analysis to identify early biomarkers and possible pathogenic therapeutic targets.


Subject(s)
COVID-19 , COVID-19/genetics , Gene Expression Profiling/methods , Humans , Neutrophil Activation , SARS-CoV-2/genetics , Transcriptome
3.
Clin Infect Dis ; 74(3): 479-489, 2022 02 11.
Article in English | MEDLINE | ID: covidwho-1684541

ABSTRACT

BACKGROUND: Increased inflammation has been well defined in coronavirus disease 2019 (COVID-19), while definitive pathways driving severe forms of this disease remain uncertain. Neutrophils are known to contribute to immunopathology in infections, inflammatory diseases, and acute respiratory distress syndrome, a primary cause of morbidity and mortality in COVID-19. Changes in neutrophil function in COVID-19 may give insight into disease pathogenesis and identify therapeutic targets. METHODS: Blood was obtained serially from critically ill COVID-19 patients for 11 days. Neutrophil extracellular trap formation (NETosis), oxidative burst, phagocytosis, and cytokine levels were assessed. Lung tissue was obtained immediately postmortem for immunostaining. PubMed searches for neutrophils, lung, and COVID-19 yielded 10 peer-reviewed research articles in English. RESULTS: Elevations in neutrophil-associated cytokines interleukin 8 (IL-8) and interleukin 6, and general inflammatory cytokines IFN-inducible protien-19, granulocyte macrophage colony-stimulating factor (GM-CSF), interleukin 1ß, interleukin 10, and tumor necrosis factor, were identified both at first measurement and across hospitalization (P < .0001). COVID-19 neutrophils had exaggerated oxidative burst (P < .0001), NETosis (P < .0001), and phagocytosis (P < .0001) relative to controls. Increased NETosis correlated with leukocytosis and neutrophilia, and neutrophils and NETs were identified within airways and alveoli in lung parenchyma of 40% of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected lungs available for examination (2 of 5). While elevations in IL-8 and absolute neutrophil count correlated with disease severity, plasma IL-8 levels alone correlated with death. CONCLUSIONS: Literature to date demonstrates compelling evidence of increased neutrophils in the circulation and lungs of COVID-19 patients. Importantly, neutrophil quantity and activation correlates with severity of disease. Similarly, our data show that circulating neutrophils in COVID-19 exhibit an activated phenotype with enhanced NETosis and oxidative burst.


Subject(s)
COVID-19 , Extracellular Traps , Critical Illness , Humans , Neutrophil Activation , Neutrophils , Phenotype , SARS-CoV-2
4.
J Immunol ; 208(4): 979-990, 2022 02 15.
Article in English | MEDLINE | ID: covidwho-1631932

ABSTRACT

Calprotectin is released by activated neutrophils along with myeloperoxidase (MPO) and proteases. It plays numerous roles in inflammation and infection, and is used as an inflammatory biomarker. However, calprotectin is readily oxidized by MPO-derived hypohalous acids to form covalent dimers of its S100A8 and S100A9 subunits. The dimers are susceptible to degradation by proteases. We show that detection of human calprotectin by ELISA declines markedly because of its oxidation by hypochlorous acid and subsequent degradation. Also, proteolysis liberates specific peptides from oxidized calprotectin that is present at inflammatory sites. We identified six calprotectin-derived peptides by mass spectrometry and detected them in the bronchoalveolar lavage fluid of children with cystic fibrosis (CF). We assessed the peptides as biomarkers of neutrophilic inflammation and infection. The content of the calprotectin peptide ILVI was related to calprotectin (r = 0.72, p = 0.01, n = 10). Four of the peptides were correlated with the concentration of MPO (r > 0.7, p ≤ 0.01, n = 21), while three were higher (p < 0.05) in neutrophil elastase-positive (n = 14) than -negative samples (n = 7). Also, five of the peptides were higher (p < 0.05) in the bronchoalveolar lavage fluid from children with CF with infections (n = 21) than from non-CF children without infections (n = 6). The specific peptides liberated from calprotectin will signal uncontrolled activity of proteases and MPO during inflammation. They may prove useful in tracking inflammation in respiratory diseases dominated by neutrophils, including coronavirus disease 2019.


Subject(s)
Bronchoalveolar Lavage Fluid/immunology , Cystic Fibrosis/immunology , Inflammation/immunology , Leukocyte L1 Antigen Complex/metabolism , Neutrophils/immunology , Peptides/metabolism , Respiratory System/metabolism , Child , Child, Preschool , Cystic Fibrosis/diagnosis , Female , Humans , Inflammation/diagnosis , Leukocyte L1 Antigen Complex/genetics , Leukocyte L1 Antigen Complex/immunology , Male , Neutrophil Activation , Oxidation-Reduction , Peptides/genetics , Peptides/immunology , Proteolysis
5.
Eur J Med Res ; 26(1): 146, 2021 Dec 17.
Article in English | MEDLINE | ID: covidwho-1582003

ABSTRACT

BACKGROUND: At the end of 2019, the world witnessed the emergence and ravages of a viral infection induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Also known as the coronavirus disease 2019 (COVID-19), it has been identified as a public health emergency of international concern (PHEIC) by the World Health Organization (WHO) because of its severity. METHODS: The gene data of 51 samples were extracted from the GSE150316 and GSE147507 data set and then processed by means of the programming language R, through which the differentially expressed genes (DEGs) that meet the standards were screened. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed on the selected DEGs to understand the functions and approaches of DEGs. The online tool STRING was employed to construct a protein-protein interaction (PPI) network of DEGs and, in turn, to identify hub genes. RESULTS: A total of 52 intersection genes were obtained through DEG identification. Through the GO analysis, we realized that the biological processes (BPs) that have the deepest impact on the human body after SARS-CoV-2 infection are various immune responses. By using STRING to construct a PPI network, 10 hub genes were identified, including IFIH1, DDX58, ISG15, EGR1, OASL, SAMD9, SAMD9L, XAF1, IFITM1, and TNFSF10. CONCLUSION: The results of this study will hopefully provide guidance for future studies on the pathophysiological mechanism of SARS-CoV-2 infection.


Subject(s)
COVID-19/genetics , Computational Biology/methods , Gene Expression Regulation/genetics , Lung/pathology , Protein Interaction Maps/genetics , COVID-19/pathology , Databases, Genetic , Gene Expression Profiling , Gene Ontology , Humans , Immunity, Humoral/genetics , Immunity, Humoral/immunology , Lung/virology , Neutrophil Activation/genetics , Neutrophil Activation/immunology , Neutrophils/immunology , SARS-CoV-2 , Transcriptome/genetics
6.
JCI Insight ; 7(2)2022 01 25.
Article in English | MEDLINE | ID: covidwho-1575230

ABSTRACT

Acute respiratory distress syndrome (ARDS) is a life-threatening syndrome, constituted by respiratory failure and diffuse alveolar damage that results from dysregulated local and systemic immune activation, causing pulmonary vascular, parenchymal, and alveolar damage. SARS-CoV-2 infection has become the dominant cause of ARDS worldwide, and emerging evidence implicates neutrophils and their cytotoxic arsenal of effector functions as central drivers of immune-mediated lung injury in COVID-19 ARDS. However, key outstanding questions are whether COVID-19 drives a unique program of neutrophil activation or effector functions that contribute to the severe pathogenesis of this pandemic illness and whether this unique neutrophil response can be targeted to attenuate disease. Using a combination of high-dimensional single-cell analysis and ex vivo functional assays of neutrophils from patients with COVID-19 ARDS, compared with those with non-COVID ARDS (caused by bacterial pneumonia), we identified a functionally distinct landscape of neutrophil activation in COVID-19 ARDS that was intrinsically programmed during SARS-CoV-2 infection. Furthermore, neutrophils in COVID-19 ARDS were functionally primed to produce high amounts of neutrophil extracellular traps. Surprisingly, this unique pathological program of neutrophil priming escaped conventional therapy with dexamethasone, thereby revealing a promising target for adjunctive immunotherapy in severe COVID-19.


Subject(s)
COVID-19/immunology , Extracellular Traps/immunology , Neutrophil Activation , Neutrophils/immunology , Respiratory Distress Syndrome/immunology , SARS-CoV-2/immunology , Adult , Aged , Aged, 80 and over , COVID-19/pathology , Female , Humans , Male , Middle Aged , Neutrophils/pathology , Pneumonia, Bacterial/immunology , Pneumonia, Bacterial/pathology , Respiratory Distress Syndrome/pathology , Severity of Illness Index
7.
Eur J Immunol ; 52(3): 484-502, 2022 03.
Article in English | MEDLINE | ID: covidwho-1555185

ABSTRACT

To better understand the mechanisms at the basis of neutrophil functions during SARS-CoV-2, we studied patients with severe COVID-19 pneumonia. They had high blood proportion of degranulated neutrophils and elevated plasma levels of myeloperoxidase (MPO), elastase, and MPO-DNA complexes, which are typical markers of neutrophil extracellular traps (NET). Their neutrophils display dysfunctional mitochondria, defective oxidative burst, increased glycolysis, glycogen accumulation in the cytoplasm, and increase glycogenolysis. Hypoxia-inducible factor 1α (ΗΙF-1α) is stabilized in such cells, and it controls the level of glycogen phosphorylase L (PYGL), a key enzyme in glycogenolysis. Inhibiting PYGL abolishes the ability of neutrophils to produce NET. Patients displayed significant increases of plasma levels of molecules involved in the regulation of neutrophils' function including CCL2, CXCL10, CCL20, IL-18, IL-3, IL-6, G-CSF, GM-CSF, IFN-γ. Our data suggest that metabolic remodelling is vital for the formation of NET and for boosting neutrophil inflammatory response, thus, suggesting that modulating ΗΙF-1α or PYGL could represent a novel approach for innovative therapies.


Subject(s)
COVID-19/immunology , COVID-19/metabolism , Neutrophils/immunology , Neutrophils/metabolism , SARS-CoV-2 , Adult , Aged , Aged, 80 and over , COVID-19/blood , Case-Control Studies , Cohort Studies , Cytokines/blood , Extracellular Traps/immunology , Extracellular Traps/metabolism , Female , Glycogen Phosphorylase, Liver Form/blood , Granulocytes/immunology , Granulocytes/metabolism , Humans , Hypoxia-Inducible Factor 1, alpha Subunit/blood , Male , Metabolic Networks and Pathways/genetics , Metabolic Networks and Pathways/immunology , Middle Aged , Neutrophil Activation , Peroxidase/blood , Respiratory Burst , Severity of Illness Index
8.
Am J Pathol ; 192(1): 112-120, 2022 01.
Article in English | MEDLINE | ID: covidwho-1506166

ABSTRACT

Severe coronavirus disease 2019 (COVID-19) increases the risk of myocardial injury that contributes to mortality. This study used multiparameter immunofluorescence to extensively examine heart autopsy tissue of 7 patients who died of COVID-19 compared to 12 control specimens, with or without cardiovascular disease. Consistent with prior reports, no evidence of viral infection or lymphocytic infiltration indicative of myocarditis was found. However, frequent and extensive thrombosis was observed in large and small vessels in the hearts of the COVID-19 cohort, findings that were infrequent in controls. The endothelial lining of thrombosed vessels typically lacked evidence of cytokine-mediated endothelial activation, assessed as nuclear expression of transcription factors p65 (RelA), pSTAT1, or pSTAT3, or evidence of inflammatory activation assessed by expression of intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), tissue factor, or von Willebrand factor (VWF). Intimal EC lining was also generally preserved with little evidence of cell death or desquamation. In contrast, there were frequent markers of neutrophil activation within myocardial thrombi in patients with COVID-19, including neutrophil-platelet aggregates, neutrophil-rich clusters within macrothrombi, and evidence of neutrophil extracellular trap (NET) formation. These findings point to alterations in circulating neutrophils rather than in the endothelium as contributors to the increased thrombotic diathesis in the hearts of COVID-19 patients.


Subject(s)
COVID-19 , Coronary Vessels , Myocarditis , Myocardium , SARS-CoV-2/metabolism , Thrombosis , Aged , Aged, 80 and over , Blood Platelets/metabolism , Blood Platelets/pathology , COVID-19/metabolism , COVID-19/pathology , Coronary Vessels/metabolism , Coronary Vessels/pathology , Endothelium, Vascular/metabolism , Endothelium, Vascular/pathology , Female , Gene Expression Regulation , Humans , Male , Middle Aged , Myocarditis/metabolism , Myocarditis/pathology , Myocardium/metabolism , Myocardium/pathology , Neutrophil Activation , Neutrophils/metabolism , Neutrophils/pathology , Platelet Aggregation , Thrombosis/metabolism , Thrombosis/pathology
9.
Inflamm Res ; 71(1): 57-67, 2022 Jan.
Article in English | MEDLINE | ID: covidwho-1491056

ABSTRACT

OBJECTIVE: Severe COVID-19 is characterized by a dysregulated immune response in which neutrophils play a critical role. Calprotectin reflects neutrophil activation and is involved in the self-amplifying thrombo-inflammatory storm in severe COVID-19. We aimed to evaluate the role of calprotectin in early prediction of severity in COVID-19 patients. METHODS: This was a multicenter prospective observational study enrolling consecutive adult COVID-19 patients. On arrival to emergency department, blood samples were collected for laboratory tests, including serum calprotectin. The primary outcome was severe respiratory failure requiring invasive mechanical ventilation and the secondary outcome was need for Intensive Care Unit (ICU) admission. RESULTS: Study population included 395 patients, 57 (14.4%) required invasive mechanical ventilation and 100 (25.3%) were admitted to ICU. Median serum calprotectin levels were significantly higher in intubated (3.73 mg/L vs. 2.63 mg/L; p < 0.001) and ICU patients (3.48 mg/L vs. 2.60 mg/L; p = 0.001). Calprotectin showed a significant accuracy to predict the need for invasive mechanical ventilation (ROC AUC 0.723) and ICU admission (ROC AUC 0.650). In multivariate analysis, serum calprotectin was an independent predictor of invasive mechanical ventilation (OR 1.161) and ICU admission (OR 1.068). CONCLUSION: Serum calprotectin can be used as an early predictor of severity in COVID-19 patients.


Subject(s)
COVID-19/blood , COVID-19/diagnosis , Leukocyte L1 Antigen Complex/blood , Neutrophil Activation , Neutrophils/cytology , Respiration, Artificial , Respiratory Insufficiency/diagnosis , Adolescent , Adult , Aged , Aged, 80 and over , Area Under Curve , COVID-19/complications , Female , Humans , Immune System , Inflammation , Intensive Care Units , Male , Middle Aged , Multivariate Analysis , Predictive Value of Tests , Prospective Studies , ROC Curve , Respiratory Insufficiency/complications , Treatment Outcome , Young Adult
10.
J Clin Invest ; 131(20)2021 10 15.
Article in English | MEDLINE | ID: covidwho-1470549

ABSTRACT

Multisystem inflammatory syndrome in children (MIS-C) manifests as a severe and uncontrolled inflammatory response with multiorgan involvement, occurring weeks after SARS-CoV-2 infection. Here, we utilized proteomics, RNA sequencing, autoantibody arrays, and B cell receptor (BCR) repertoire analysis to characterize MIS-C immunopathogenesis and identify factors contributing to severe manifestations and intensive care unit admission. Inflammation markers, humoral immune responses, neutrophil activation, and complement and coagulation pathways were highly enriched in MIS-C patient serum, with a more hyperinflammatory profile in severe than in mild MIS-C cases. We identified a strong autoimmune signature in MIS-C, with autoantibodies targeted to both ubiquitously expressed and tissue-specific antigens, suggesting autoantigen release and excessive antigenic drive may result from systemic tissue damage. We further identified a cluster of patients with enhanced neutrophil responses as well as high anti-Spike IgG and autoantibody titers. BCR sequencing of these patients identified a strong imprint of antigenic drive with substantial BCR sequence connectivity and usage of autoimmunity-associated immunoglobulin heavy chain variable region (IGHV) genes. This cluster was linked to a TRBV11-2 expanded T cell receptor (TCR) repertoire, consistent with previous studies indicating a superantigen-driven pathogenic process. Overall, we identify a combination of pathogenic pathways that culminate in MIS-C and may inform treatment.


Subject(s)
Autoimmunity , COVID-19/complications , Systemic Inflammatory Response Syndrome/immunology , Adaptive Immunity , Adolescent , Biomarkers/metabolism , COVID-19/genetics , COVID-19/immunology , COVID-19/metabolism , Case-Control Studies , Child , Child, Preschool , Cohort Studies , Cytokine Release Syndrome/immunology , Female , Humans , Infant , Inflammation/immunology , Male , Mucocutaneous Lymph Node Syndrome/genetics , Mucocutaneous Lymph Node Syndrome/immunology , Mucocutaneous Lymph Node Syndrome/metabolism , Neutrophil Activation , Proteomics , RNA-Seq , Receptors, Antigen, B-Cell/genetics , Severity of Illness Index , Systemic Inflammatory Response Syndrome/genetics , Systemic Inflammatory Response Syndrome/metabolism
11.
J Clin Invest ; 131(20)2021 10 15.
Article in English | MEDLINE | ID: covidwho-1470547

ABSTRACT

BACKGROUNDMultisystem inflammatory syndrome in children (MIS-C) is a rare but potentially severe illness that follows exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Kawasaki disease (KD) shares several clinical features with MIS-C, which prompted the use of intravenous immunoglobulin (IVIG), a mainstay therapy for KD. Both diseases share a robust activation of the innate immune system, including the IL-1 signaling pathway, and IL-1 blockade has been used for the treatment of both MIS-C and KD. The mechanism of action of IVIG in these 2 diseases and the cellular source of IL-1ß have not been defined.METHODSThe effects of IVIG on peripheral blood leukocyte populations from patients with MIS-C and KD were examined using flow cytometry and mass cytometry (CyTOF) and live-cell imaging.RESULTSCirculating neutrophils were highly activated in patients with KD and MIS-C and were a major source of IL-1ß. Following IVIG treatment, activated IL-1ß+ neutrophils were reduced in the circulation. In vitro, IVIG was a potent activator of neutrophil cell death via PI3K and NADPH oxidase, but independently of caspase activation.CONCLUSIONSActivated neutrophils expressing IL-1ß can be targeted by IVIG, supporting its use in both KD and MIS-C to ameliorate inflammation.FUNDINGPatient Centered Outcomes Research Institute; NIH; American Asthma Foundation; American Heart Association; Novo Nordisk Foundation; NIGMS; American Academy of Allergy, Asthma and Immunology Foundation.


Subject(s)
COVID-19/complications , Immunoglobulins, Intravenous/therapeutic use , Mucocutaneous Lymph Node Syndrome/immunology , Mucocutaneous Lymph Node Syndrome/therapy , Systemic Inflammatory Response Syndrome/immunology , Systemic Inflammatory Response Syndrome/therapy , COVID-19/blood , COVID-19/immunology , COVID-19/therapy , Case-Control Studies , Cell Death/immunology , Cell Lineage/immunology , Child , Child, Preschool , Fas Ligand Protein/immunology , Female , Humans , Infant , Interleukin-1beta/antagonists & inhibitors , Interleukin-1beta/blood , Leukocyte Count , Male , Mucocutaneous Lymph Node Syndrome/blood , Neutrophil Activation , Neutrophils/classification , Neutrophils/immunology , Neutrophils/pathology , Systemic Inflammatory Response Syndrome/blood
12.
Blood ; 139(14): 2130-2144, 2022 Apr 07.
Article in English | MEDLINE | ID: covidwho-1457448

ABSTRACT

Modulation of neutrophil recruitment and function is crucial for targeting inflammatory cells to sites of infection to combat invading pathogens while, at the same time, limiting host tissue injury or autoimmunity. The underlying mechanisms regulating recruitment of neutrophils, 1 of the most abundant inflammatory cells, have gained increasing interest over the years. The previously described classical recruitment cascade of leukocytes has been extended to include capturing, rolling, adhesion, crawling, and transmigration, as well as a reverse-transmigration step that is crucial for balancing immune defense and control of remote organ endothelial leakage. Current developments in the field emphasize the importance of cellular interplay, tissue environmental cues, circadian rhythmicity, detection of neutrophil phenotypes, differential chemokine sensing, and contribution of distinct signaling components to receptor activation and integrin conformations. The use of therapeutics modulating neutrophil activation responses, as well as mutations causing dysfunctional neutrophil receptors and impaired signaling cascades, have been defined in translational animal models. Human correlates of such mutations result in increased susceptibility to infections or organ damage. This review focuses on current advances in the understanding of the regulation of neutrophil recruitment and functionality and translational implications of current discoveries in the field with a focus on acute inflammation and sepsis.


Subject(s)
Neutrophil Activation , Neutrophils , Animals , Humans , Inflammation , Integrins , Neutrophil Infiltration
13.
Trends Immunol ; 42(10): 846-848, 2021 10.
Article in English | MEDLINE | ID: covidwho-1446747

ABSTRACT

Selectively targeting facets of neutrophil function could benefit infectious and inflammatory diseases. Amara et al. report on a compound which blocks human neutrophil activation by activating the glycolytic enzyme phosphofructokinase, liver-type (PFKL). Altering glucose fate by modulating this key enzymatic step could dramatically alter the function and fate of phagocytes.


Subject(s)
Neutrophils , Phagocytes , Glucose , Humans , Neutrophil Activation , Phosphofructokinase-1
14.
JCI Insight ; 6(18)2021 09 22.
Article in English | MEDLINE | ID: covidwho-1435144

ABSTRACT

Neutrophils provide a critical line of defense in immune responses to various pathogens, inflicting self-damage upon transition to a hyperactivated, procoagulant state. Recent work has highlighted proinflammatory neutrophil phenotypes contributing to lung injury and acute respiratory distress syndrome (ARDS) in patients with coronavirus disease 2019 (COVID-19). Here, we use state-of-the art mass spectrometry-based proteomics and transcriptomic and correlative analyses as well as functional in vitro and in vivo studies to dissect how neutrophils contribute to the progression to severe COVID-19. We identify a reinforcing loop of both systemic and neutrophil intrinsic IL-8 (CXCL8/IL-8) dysregulation, which initiates and perpetuates neutrophil-driven immunopathology. This positive feedback loop of systemic and neutrophil autocrine IL-8 production leads to an activated, prothrombotic neutrophil phenotype characterized by degranulation and neutrophil extracellular trap (NET) formation. In severe COVID-19, neutrophils directly initiate the coagulation and complement cascade, highlighting a link to the immunothrombotic state observed in these patients. Targeting the IL-8-CXCR-1/-2 axis interferes with this vicious cycle and attenuates neutrophil activation, degranulation, NETosis, and IL-8 release. Finally, we show that blocking IL-8-like signaling reduces severe acute respiratory distress syndrome of coronavirus 2 (SARS-CoV-2) spike protein-induced, human ACE2-dependent pulmonary microthrombosis in mice. In summary, our data provide comprehensive insights into the activation mechanisms of neutrophils in COVID-19 and uncover a self-sustaining neutrophil-IL-8 axis as a promising therapeutic target in severe SARS-CoV-2 infection.


Subject(s)
COVID-19/metabolism , Interleukin-8/metabolism , Lung/immunology , Neutrophils/immunology , SARS-CoV-2 , Thrombosis/etiology , Animals , COVID-19/complications , COVID-19/pathology , Humans , Lung/pathology , Mice , Neutrophil Activation , Neutrophils/pathology , Phenotype , Thrombosis/pathology
15.
Int J Mol Sci ; 22(2)2021 Jan 08.
Article in English | MEDLINE | ID: covidwho-1389386

ABSTRACT

Neutrophils are primary effector cells of innate immunity and fight infection by phagocytosis and degranulation. Activated neutrophils also release neutrophil extracellular traps (NETs) in response to a variety of stimuli. These NETs are net-like complexes composed of cell-free DNA, histones and neutrophil granule proteins. Besides the evolutionarily conserved mechanism to capture and eliminate pathogens, NETs are also associated with pathophysiological processes of various diseases. Here, we elucidate the mechanisms of NET formation and their different implications in disease. We focused on autoinflammatory and cardiovascular disorders as the leading cause of death. Neutrophil extracellular traps are not only present in various cardiovascular diseases but play an essential role in atherosclerotic plaque formation, arterial and venous thrombosis, as well as in the development and progression of abdominal aortic aneurysms. Furthermore, NETosis can be considered as a source of autoantigens and maintains an inflammatory milieu promoting autoimmune diseases. Indeed, there is further need for research into the balance between NET induction, inhibition, and degradation in order to pharmacologically target NETs and their compounds without impairing the patient's immune defense. This review may be of interest to both basic scientists and clinicians to stimulate translational research and innovative clinical approaches.


Subject(s)
Autoimmune Diseases/immunology , Extracellular Traps/immunology , Neutrophils/immunology , Aortic Aneurysm, Abdominal/pathology , Autoimmune Diseases/pathology , Autoimmunity/immunology , COVID-19/immunology , COVID-19/pathology , Humans , Neutrophil Activation/immunology , Plaque, Atherosclerotic/pathology , Thrombosis/pathology
16.
Int J Mol Sci ; 22(16)2021 Aug 17.
Article in English | MEDLINE | ID: covidwho-1360774

ABSTRACT

Neutrophil extracellular traps (NETs), built from mitochondrial or nuclear DNA, proteinases, and histones, entrap and eliminate pathogens in the course of bacterial or viral infections. Neutrophils' activation and the formation of NETs have been described as major risk factors for acute lung injury, multi-organ damage, and mortality in COVID-19 disease. NETs-related lung injury involves both epithelial and endothelial cells, as well as the alveolar-capillary barrier. The markers for NETs formation, such as circulating DNA, neutrophil elastase (NE) activity, or myeloperoxidase-DNA complexes, were found in lung specimens of COVID-19 victims, as well as in sera and tracheal aspirates obtained from COVID-19 patients. DNA threads form large conglomerates causing local obstruction of the small bronchi and together with NE are responsible for overproduction of mucin by epithelial cells. Various components of NETs are involved in the pathogenesis of cytokine storm in SARS-CoV-2 pulmonary disease. NETs are responsible for the interplay between inflammation and thrombosis in the affected lungs. The immunothrombosis, stimulated by NETs, has a poor prognostic significance. Better understanding of the role of NETs in the course of COVID-19 can help to develop novel approaches to the therapeutic interventions in this condition.


Subject(s)
COVID-19/immunology , Extracellular Traps/virology , Lung/immunology , Neutrophils/immunology , SARS-CoV-2/immunology , COVID-19/pathology , COVID-19/virology , Cytokine Release Syndrome/immunology , Cytokine Release Syndrome/virology , Endothelial Cells/pathology , Epithelial Cells/pathology , Extracellular Traps/immunology , Histones/immunology , Humans , Leukocyte Elastase/deficiency , Leukocyte Elastase/immunology , Lung/pathology , Lung/virology , Neutrophil Activation , Neutrophils/virology , Peroxidase/immunology
17.
J Infect Dis ; 224(4): 575-585, 2021 08 16.
Article in English | MEDLINE | ID: covidwho-1358459

ABSTRACT

Severe coronavirus disease 2019 (COVID-19) is associated with an overactive inflammatory response mediated by macrophages. Here, we analyzed the phenotype and function of neutrophils in patients with COVID-19. We found that neutrophils from patients with severe COVID-19 express high levels of CD11b and CD66b, spontaneously produce CXCL8 and CCL2, and show a strong association with platelets. Production of CXCL8 correlated with plasma concentrations of lactate dehydrogenase and D-dimer. Whole blood assays revealed that neutrophils from patients with severe COVID-19 show a clear association with immunoglobulin G (IgG) immune complexes. Moreover, we found that sera from patients with severe disease contain high levels of immune complexes and activate neutrophils through a mechanism partially dependent on FcγRII (CD32). Interestingly, when integrated in immune complexes, anti-severe acute respiratory syndrome coronavirus 2 IgG antibodies from patients with severe COVID-19 displayed a higher proinflammatory profile compared with antibodies from patients with mild disease. Our study suggests that IgG immune complexes might promote the acquisition of an inflammatory signature by neutrophils, worsening the course of COVID-19.


Subject(s)
Antibodies, Viral/immunology , Antigen-Antibody Complex/immunology , COVID-19/immunology , Immunoglobulin G/immunology , Neutrophil Activation/immunology , Adult , Aged , Antibodies, Viral/blood , Antigen-Antibody Complex/blood , Antigens, CD/immunology , CD11b Antigen/immunology , Cell Adhesion Molecules/immunology , Female , GPI-Linked Proteins/immunology , Humans , Immunoglobulin G/blood , Interleukin-8/immunology , Male , Middle Aged , Neutrophils/immunology , Receptors, IgG/immunology , SARS-CoV-2/immunology , Young Adult
18.
Front Immunol ; 12: 631821, 2021.
Article in English | MEDLINE | ID: covidwho-1344260

ABSTRACT

Neutrophils or polymorphonuclear leukocytes (PMN) are key participants in the innate immune response for their ability to execute different effector functions. These cells express a vast array of membrane receptors that allow them to recognize and eliminate infectious agents effectively and respond appropriately to microenvironmental stimuli that regulate neutrophil functions, such as activation, migration, generation of reactive oxygen species, formation of neutrophil extracellular traps, and mediator secretion, among others. Currently, it has been realized that activated neutrophils can accomplish their effector functions and simultaneously activate mechanisms of cell death in response to different intracellular or extracellular factors. Although several studies have revealed similarities between the mechanisms of cell death of neutrophils and other cell types, neutrophils have distinctive properties, such as a high production of reactive oxygen species (ROS) and nitrogen species (RNS), that are important for their effector function in infections and pathologies such as cancer, autoimmune diseases, and immunodeficiencies, influencing their cell death mechanisms. The present work offers a synthesis of the conditions and molecules implicated in the regulation and activation of the processes of neutrophil death: apoptosis, autophagy, pyroptosis, necroptosis, NETosis, and necrosis. This information allows to understand the duality encountered by PMNs upon activation. The effector functions are carried out to eliminate invading pathogens, but in several instances, these functions involve activation of signaling cascades that culminate in the death of the neutrophil. This process guarantees the correct elimination of pathogenic agents, damaged or senescent cells, and the timely resolution of the inflammation that is essential for the maintenance of homeostasis in the organism. In addition, they alert the organism when the immunological system is being deregulated, promoting the activation of other cells of the immune system, such as B and T lymphocytes, which produce cytokines that potentiate the microbicide functions.


Subject(s)
Cell Death/immunology , Neutrophils/pathology , Apoptosis/immunology , Apoptosis Regulatory Proteins/metabolism , Autophagy/immunology , Extracellular Traps/immunology , Extracellular Traps/metabolism , Free Radicals/metabolism , Humans , Necroptosis/immunology , Necrosis/immunology , Necrosis/metabolism , Neutrophil Activation , Neutrophils/immunology , Neutrophils/metabolism , Phagocytosis/immunology , Pyroptosis/immunology , Receptors, Death Domain/metabolism
19.
Biochem Biophys Res Commun ; 565: 64-71, 2021 08 06.
Article in English | MEDLINE | ID: covidwho-1251023

ABSTRACT

Neutrophil extracellular traps (NETs) are extracellular webs of DNA, histones and granular contents that are released by neutrophils to control infections. However, NETs that is not properly regulated can propagate inflammation and thrombosis. It was recognized that viruses can induce NETs. As a synthetic analog of viral double-stranded (ds) RNA, polyinosinic-polycytidylic acid [poly(I:C)] is known to induce inflammation and thrombosis. However, whether and how poly(I:C) modulates NETs remains unclear. Here, we have demonstrated that poly(I:C) induced extracellular DNA traps in human neutrophils in a dose-dependent manner. Further, poly(I:C) or dsRNA virus elevated the levels of myeloperoxidase-DNA complexes and citrullinated histone H3, which are specific markers of NETs, in both neutrophil supernatants and mouse plasma. Interestingly, a potent peptidylarginine deiminase 4 (PAD4) inhibitor, BB-CL-Amidine (BB-CLA) or PAD4 knockdown effectively prevented poly(I:C)-induced NETs formation and release. In addition, BB-CLA abrogated poly(I:C)-triggered neutrophil activation and infiltration, and vascular permeability in lungs. BB-CLA also attenuated poly(I:C)-induced thrombocytopenia in circulation, fibrin deposition and thrombus formation in tissues. Taken together, these results suggest that viral mimetic poly(I:C) may induce NETs-dependent inflammation and thrombosis through PAD4, and that inhibiting PAD4 may become a good strategy to protect against viral infection-caused inflammation/thrombosis-related pathological conditions of diseases.


Subject(s)
Extracellular Traps/drug effects , Inflammation/metabolism , Neutrophils/drug effects , Poly I-C/pharmacology , Protein-Arginine Deiminase Type 4/metabolism , Thrombosis/metabolism , Amidines/pharmacology , Animals , Cells, Cultured , Chlorocebus aethiops , Humans , Inflammation/pathology , Male , Mice , Mice, Inbred C57BL , Neutrophil Activation/drug effects , Neutrophils/metabolism , Protein-Arginine Deiminase Type 4/antagonists & inhibitors , Thrombosis/pathology
20.
JCI Insight ; 6(14)2021 07 22.
Article in English | MEDLINE | ID: covidwho-1320461

ABSTRACT

BACKGROUNDIndividuals recovering from COVID-19 frequently experience persistent respiratory ailments, which are key elements of postacute sequelae of SARS-CoV-2 infection (PASC); however, little is known about the underlying biological factors that may direct lung recovery and the extent to which these are affected by COVID-19 severity.METHODSWe performed a prospective cohort study of individuals with persistent symptoms after acute COVID-19, collecting clinical data, pulmonary function tests, and plasma samples used for multiplex profiling of inflammatory, metabolic, angiogenic, and fibrotic factors.RESULTSSixty-one participants were enrolled across 2 academic medical centers at a median of 9 weeks (interquartile range, 6-10 weeks) after COVID-19 illness: n = 13 participants (21%) had mild COVID-19 and were not hospitalized, n = 30 participants (49%) were hospitalized but were considered noncritical, and n = 18 participants (30%) were hospitalized and in the intensive care unit (ICU). Fifty-three participants (85%) had lingering symptoms, most commonly dyspnea (69%) and cough (58%). Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and diffusing capacity for carbon monoxide (DLCO) declined as COVID-19 severity increased (P < 0.05) but these values did not correlate with respiratory symptoms. Partial least-squares discriminant analysis of plasma biomarker profiles clustered participants by past COVID-19 severity. Lipocalin-2 (LCN2), MMP-7, and HGF identified by our analysis were significantly higher in the ICU group (P < 0.05), inversely correlated with FVC and DLCO (P < 0.05), and were confirmed in a separate validation cohort (n = 53).CONCLUSIONSubjective respiratory symptoms are common after acute COVID-19 illness but do not correlate with COVID-19 severity or pulmonary function. Host response profiles reflecting neutrophil activation (LCN2), fibrosis signaling (MMP-7), and alveolar repair (HGF) track with lung impairment and may be novel therapeutic or prognostic targets.FundingNational Heart, Lung, and Blood Institute (K08HL130557 and R01HL142818), American Heart Association (Transformational Project Award), the DeLuca Foundation Award, a donation from Jack Levin to the Benign Hematology Program at Yale University, and Duke University.


Subject(s)
COVID-19/complications , Hepatocyte Growth Factor/analysis , Lipocalin-2/analysis , Matrix Metalloproteinase 7/analysis , Pulmonary Fibrosis , Respiratory Function Tests , COVID-19/diagnosis , COVID-19/immunology , COVID-19/physiopathology , Cough/diagnosis , Cough/etiology , Dyspnea/diagnosis , Dyspnea/etiology , Female , Humans , Lung/metabolism , Lung/pathology , Lung/physiopathology , Male , Middle Aged , Neutrophil Activation/immunology , Prognosis , Pulmonary Fibrosis/diagnosis , Pulmonary Fibrosis/etiology , Pulmonary Fibrosis/metabolism , Recovery of Function/immunology , Respiratory Function Tests/methods , Respiratory Function Tests/statistics & numerical data , SARS-CoV-2 , Severity of Illness Index
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