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1.
Shock ; 57(1): 1-6, 2022 01 01.
Article in English | MEDLINE | ID: covidwho-2191212

ABSTRACT

BACKGROUND: The pathomechanisms of hypoxemia and treatment strategies for type H and type L acute respiratory distress syndrome (ARDS) in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-induced coronavirus disease 2019 (COVID-19) have not been elucidated. MAIN TEXT: SARS-CoV-2 mainly targets the lungs and blood, leading to ARDS, and systemic thrombosis or bleeding. Angiotensin II-induced coagulopathy, SARS-CoV-2-induced hyperfibrin(ogen)olysis, and pulmonary and/or disseminated intravascular coagulation due to immunothrombosis contribute to COVID-19-associated coagulopathy. Type H ARDS is associated with hypoxemia due to diffuse alveolar damage-induced high right-to-left shunts. Immunothrombosis occurs at the site of infection due to innate immune inflammatory and coagulofibrinolytic responses to SARS-CoV-2, resulting in microvascular occlusion with hypoperfusion of the lungs. Lung immunothrombosis in type L ARDS results from neutrophil extracellular traps containing platelets and fibrin in the lung microvasculature, leading to hypoxemia due to impaired blood flow and a high ventilation/perfusion (VA/Q) ratio. COVID-19-associated ARDS is more vascular centric than the other types of ARDS. D-dimer levels have been monitored for the progression of microvascular thrombosis in COVID-19 patients. Early anticoagulation therapy in critical patients with high D-dimer levels may improve prognosis, including the prevention and/or alleviation of ARDS. CONCLUSIONS: Right-to-left shunts and high VA/Q ratios caused by lung microvascular thrombosis contribute to hypoxemia in type H and L ARDS, respectively. D-dimer monitoring-based anticoagulation therapy may prevent the progression to and/or worsening of ARDS in COVID-19 patients.


Subject(s)
COVID-19/physiopathology , Hemostasis/physiology , Hypoxia/physiopathology , Respiratory Distress Syndrome/physiopathology , Thrombosis/physiopathology , Anticoagulants/therapeutic use , Biomarkers/blood , Blood Platelets/metabolism , COVID-19/drug therapy , Extracellular Traps/metabolism , Fibrin/metabolism , Fibrin Fibrinogen Degradation Products/analysis , Fibrinolysis , Humans , Lung/blood supply , Microvessels/physiopathology , Phenotype , Respiratory Distress Syndrome/drug therapy , SARS-CoV-2 , Thrombosis/drug therapy
2.
Nat Commun ; 13(1): 5206, 2022 09 05.
Article in English | MEDLINE | ID: covidwho-2008281

ABSTRACT

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare yet serious adverse effect of the adenoviral vector vaccines ChAdOx1 nCoV-19 (AstraZeneca) and Ad26.COV2.S (Janssen) against COVID-19. The mechanisms involved in clot formation and thrombocytopenia in VITT are yet to be fully determined. Here we show neutrophils undergoing NETosis and confirm expression markers of NETs in VITT patients. VITT antibodies directly stimulate neutrophils to release NETs and induce thrombus formation containing abundant platelets, neutrophils, fibrin, extracellular DNA and citrullinated histone H3 in a flow microfluidics system and in vivo. Inhibition of NETosis prevents VITT-induced thrombosis in mice but not thrombocytopenia. In contrast, in vivo blockage of FcγRIIa abrogates both thrombosis and thrombocytopenia suggesting these are distinct processes. Our findings indicate that anti-PF4 antibodies activate blood cells via FcγRIIa and are responsible for thrombosis and thrombocytopenia in VITT. Future development of NETosis and FcγRIIa inhibitors are needed to treat VITT and similar immune thrombotic thrombocytopenia conditions more effectively, leading to better patient outcomes.


Subject(s)
COVID-19 , Extracellular Traps , Purpura, Thrombocytopenic, Idiopathic , Thrombocytopenia , Thrombosis , Vaccines , Ad26COVS1 , Animals , ChAdOx1 nCoV-19 , Extracellular Traps/metabolism , Humans , Mice , Purpura, Thrombocytopenic, Idiopathic/chemically induced , Thrombocytopenia/chemically induced , Thrombosis/prevention & control , Vaccines/metabolism
3.
Front Immunol ; 13: 953195, 2022.
Article in English | MEDLINE | ID: covidwho-1990285

ABSTRACT

Acute lung injury (ALI) is a heterogeneous inflammatory condition associated with high morbidity and mortality. Neutrophils play a key role in the development of different forms of ALI, and the release of neutrophil extracellular traps (NETs) is emerging as a common pathogenic mechanism. NETs are essential in controlling pathogens, and their defective release or increased degradation leads to a higher risk of infection. However, NETs also contain several pro-inflammatory and cytotoxic molecules than can exacerbate thromboinflammation and lung tissue injury. To reduce NET-mediated lung damage and inflammation, DNase is frequently used in preclinical models of ALI due to its capability of digesting NET DNA scaffold. Moreover, recent advances in neutrophil biology led to the development of selective NET inhibitors, which also appear to reduce ALI in experimental models. Here we provide an overview of the role of NETs in different forms of ALI discussing existing gaps in our knowledge and novel therapeutic approaches to modulate their impact on lung injury.


Subject(s)
Acute Lung Injury , Extracellular Traps , Thrombosis , Acute Lung Injury/pathology , Extracellular Traps/metabolism , Humans , Inflammation/metabolism , Neutrophils/metabolism , Thrombosis/metabolism
4.
Biomolecules ; 12(8)2022 07 27.
Article in English | MEDLINE | ID: covidwho-1969083

ABSTRACT

Background: Neutrophil extracellular traps' (NETs') formation is a mechanism of defense that neutrophils deploy as an alternative to phagocytosis, to constrain the spread of microorganisms. Aim: The aim was to evaluate biomarkers of NETs' formation in a patient cohort admitted to intensive care unit (ICU) due to infection. Methods: Forty-six septic shock patients, 22 critical COVID-19 patients and 48 matched control subjects were recruited. Intact nucleosomes containing histone 3.1 (Nu.H3.1), or citrullinated histone H3R8 (Nu.Cit-H3R8), free citrullinated histone (Cit-H3), neutrophil elastase (NE) and myeloperoxidase (MPO) were measured. Results: Significant differences in Nu.H3.1 and NE levels were observed between septic shock and critical COVID-19 subjects as well as with controls (p-values < 0.05). The normalization of nucleosome levels according to the neutrophil count improved the discrimination between septic shock and critical COVID-19 patients. The ratio of Nu.Cit-H3R8 to Nu.H3.1 allowed the determination of nucleosome citrullination degree, presumably by PAD4. Conclusions: H3.1 and Cit-H3R8 nucleosomes appear to be interesting markers of global cell death and neutrophil activation when combined. Nu.H3.1 permits the evaluation of disease severity and differs between septic shock and critical COVID-19 patients, reflecting two distinct potential pathological processes in these conditions.


Subject(s)
COVID-19 , Extracellular Traps , Shock, Septic , Biomarkers/metabolism , Extracellular Traps/metabolism , Histones/metabolism , Humans , Neutrophils/metabolism , Nucleosomes/metabolism , Shock, Septic/metabolism
5.
Arterioscler Thromb Vasc Biol ; 42(9): 1103-1112, 2022 09.
Article in English | MEDLINE | ID: covidwho-1950525

ABSTRACT

The activating interplay of thrombosis and inflammation (thromboinflammation) has been established as a major underlying pathway, driving not only cardiovascular disease but also autoimmune disease and most recently, COVID-19. Throughout the years, innate immune cells have emerged as important modulators of this process. As the most abundant white blood cell in humans, neutrophils are well-positioned to propel thromboinflammation. This includes their ability to trigger an organized cell death pathway with the release of decondensed chromatin structures called neutrophil extracellular traps. Decorated with histones and cytoplasmic and granular proteins, neutrophil extracellular traps exert cytotoxic, immunogenic, and prothrombotic effects accelerating disease progression. Distinct steps leading to extracellular DNA release (NETosis) require the activities of PAD4 (protein arginine deiminase 4) catalyzing citrullination of histones and are supported by neutrophil inflammasome. By linking the immunologic function of neutrophils with the procoagulant and proinflammatory activities of monocytes and platelets, PAD4 activity holds important implications for understanding the processes that fuel thromboinflammation. We will also discuss mechanisms whereby vascular occlusion in thromboinflammation depends on the interaction of neutrophil extracellular traps with ultra-large VWF (von Willebrand Factor) and speculate on the importance of PAD4 in neutrophil inflammasome assembly and neutrophil extracellular traps in thromboinflammatory diseases including atherosclerosis and COVID-19.


Subject(s)
Atherosclerosis , COVID-19 , Extracellular Traps , Thrombosis , Atherosclerosis/metabolism , Extracellular Traps/metabolism , Histones/metabolism , Humans , Inflammasomes/metabolism , Inflammation/metabolism , Neutrophils/metabolism , Thromboinflammation , Thrombosis/etiology , Thrombosis/metabolism , von Willebrand Factor/metabolism
6.
Crit Care ; 26(1): 206, 2022 07 07.
Article in English | MEDLINE | ID: covidwho-1923570

ABSTRACT

BACKGROUND: The release of neutrophil extracellular traps (NETs) is associated with inflammation, coagulopathy, and organ damage found in severe cases of COVID-19. However, the molecular mechanisms underlying the release of NETs in COVID-19 remain unclear. OBJECTIVES: We aim to investigate the role of the Gasdermin-D (GSDMD) pathway on NETs release and the development of organ damage during COVID-19. METHODS: We performed a single-cell transcriptome analysis in public data of bronchoalveolar lavage. Then, we enrolled 63 hospitalized patients with moderate and severe COVID-19. We analyze in blood and lung tissue samples the expression of GSDMD, presence of NETs, and signaling pathways upstreaming. Furthermore, we analyzed the treatment with disulfiram in a mouse model of SARS-CoV-2 infection. RESULTS: We found that the SARS-CoV-2 virus directly activates the pore-forming protein GSDMD that triggers NET production and organ damage in COVID-19. Single-cell transcriptome analysis revealed that the expression of GSDMD and inflammasome-related genes were increased in COVID-19 patients. High expression of active GSDMD associated with NETs structures was found in the lung tissue of COVID-19 patients. Furthermore, we showed that activation of GSDMD in neutrophils requires active caspase1/4 and live SARS-CoV-2, which infects neutrophils. In a mouse model of SARS-CoV-2 infection, the treatment with disulfiram inhibited NETs release and reduced organ damage. CONCLUSION: These results demonstrated that GSDMD-dependent NETosis plays a critical role in COVID-19 immunopathology and suggests GSDMD as a novel potential target for improving the COVID-19 therapeutic strategy.


Subject(s)
COVID-19 , Extracellular Traps , Animals , COVID-19/drug therapy , Disulfiram/metabolism , Extracellular Traps/metabolism , Mice , Neutrophils/metabolism , SARS-CoV-2
7.
Ann Clin Lab Sci ; 52(3): 374-381, 2022 May.
Article in English | MEDLINE | ID: covidwho-1918736

ABSTRACT

OBJECTIVE: Exploration of biomarkers to predict the severity of COVID-19 is important to reduce mortality. Upon COVID-19 infection, neutrophil extracellular traps (NET) are formed, which leads to a cytokine storm and host damage. Hence, the extent of NET formation may reflect disease progression and predict mortality in COVID-19. METHODS: We measured 4 NET parameters - cell-free double stranded DNA (cell-free dsDNA), neutrophil elastase, citrullinated histone H3 (Cit-H3), and histone - DNA complex - in 188 COVID-19 patients and 20 healthy controls. Survivors (n=166) were hospitalized with or without oxygen supplementation, while non-survivors (n=22) expired during in-hospital treatment. RESULTS: Cell-free dsDNA was significantly elevated in non-survivors in comparison with survivors and controls. The survival rate of patients with high levels of cell-free dsDNA, neutrophil elastase, and Cit-H3 was significantly lower than that of patients with low levels. These three markers significantly correlated with inflammatory markers (absolute neutrophil count and C-reactive protein). CONCLUSION: Since the increase in NET parameters indicates the unfavourable course of COVID-19 infection, patients predisposed to poor outcome can be rapidly managed through risk stratification by using these NET parameters.


Subject(s)
COVID-19 , Extracellular Traps , Biomarkers/metabolism , COVID-19/diagnosis , Cell-Free Nucleic Acids/blood , Cell-Free Nucleic Acids/metabolism , Extracellular Traps/metabolism , Histones/blood , Histones/metabolism , Humans , Leukocyte Elastase/blood , Leukocyte Elastase/metabolism , Neutrophils/metabolism , Prognosis
8.
Sci Rep ; 12(1): 11078, 2022 06 30.
Article in English | MEDLINE | ID: covidwho-1908298

ABSTRACT

Immune cell chemotaxis to the sites of pathogen invasion is critical for fighting infection, but in life-threatening conditions such as sepsis and Covid-19, excess activation of the innate immune system is thought to cause a damaging invasion of immune cells into tissues and a consequent excessive release of cytokines, chemokines and neutrophil extracellular traps (NETs). In these circumstances, tempering excessive activation of the innate immune system may, paradoxically, promote recovery. Here we identify the antimalarial compound artemisinin as a potent and selective inhibitor of neutrophil and macrophage chemotaxis induced by a range of chemotactic agents. Artemisinin released calcium from intracellular stores in a similar way to thapsigargin, a known inhibitor of the Sarco/Endoplasmic Reticulum Calcium ATPase pump (SERCA), but unlike thapsigargin, artemisinin blocks only the SERCA3 isoform. Inhibition of SERCA3 by artemisinin was irreversible and was inhibited by iron chelation, suggesting iron-catalysed alkylation of a specific cysteine residue in SERCA3 as the mechanism by which artemisinin inhibits neutrophil motility. In murine infection models, artemisinin potently suppressed neutrophil invasion into both peritoneum and lung in vivo and inhibited the release of cytokines/chemokines and NETs. This work suggests that artemisinin may have value as a therapy in conditions such as sepsis and Covid-19 in which over-activation of the innate immune system causes tissue injury that can lead to death.


Subject(s)
Artemisinins , COVID-19 , Extracellular Traps , Macrophages , Neutrophils , Sepsis , Animals , Artemisinins/pharmacology , COVID-19/drug therapy , Calcium/metabolism , Calcium-Transporting ATPases/metabolism , Chemotaxis/drug effects , Cytokines/biosynthesis , Cytokines/metabolism , Extracellular Traps/metabolism , Macrophages/drug effects , Macrophages/metabolism , Mice , Neutrophils/drug effects , Neutrophils/metabolism , Thapsigargin/pharmacology
9.
Front Immunol ; 13: 879686, 2022.
Article in English | MEDLINE | ID: covidwho-1903014

ABSTRACT

Neutrophils play a significant role in determining disease severity following SARS-CoV-2 infection. Gene and protein expression defines several neutrophil clusters in COVID-19, including the emergence of low density neutrophils (LDN) that are associated with severe disease. The functional capabilities of these neutrophil clusters and correlation with gene and protein expression are unknown. To define host defense and immunosuppressive functions of normal density neutrophils (NDN) and LDN from COVID-19 patients, we recruited 64 patients with severe COVID-19 and 26 healthy donors (HD). Phagocytosis, respiratory burst activity, degranulation, neutrophil extracellular trap (NET) formation, and T-cell suppression in those neutrophil subsets were measured. NDN from severe/critical COVID-19 patients showed evidence of priming with enhanced phagocytosis, respiratory burst activity, and degranulation of secretory vesicles and gelatinase and specific granules, while NET formation was similar to HD NDN. COVID LDN response was impaired except for enhanced NET formation. A subset of COVID LDN with intermediate CD16 expression (CD16Int LDN) promoted T cell proliferation to a level similar to HD NDN, while COVID NDN and the CD16Hi LDN failed to stimulate T-cell activation. All 3 COVID-19 neutrophil populations suppressed stimulation of IFN-γ production, compared to HD NDN. We conclude that NDN and LDN from COVID-19 patients possess complementary functional capabilities that may act cooperatively to determine disease severity. We predict that global neutrophil responses that induce COVID-19 ARDS will vary depending on the proportion of neutrophil subsets.


Subject(s)
COVID-19 , Extracellular Traps , Extracellular Traps/metabolism , Humans , Neutrophils/metabolism , Respiratory Burst , SARS-CoV-2
10.
Sci Rep ; 12(1): 9915, 2022 06 15.
Article in English | MEDLINE | ID: covidwho-1890270

ABSTRACT

Despite the introduction of vaccines, COVID-19 still affects millions of people worldwide. A better understanding of pathophysiology and the discovery of novel therapies are needed. One of the cells of interest in COVID-19 is the neutrophil. This cell type is being recruited to a site of inflammation as one of the first immune cells. In this project, we investigated a variety of neutrophils phenotypes during COVID-19 by measuring the expression of markers for migration, maturity, activation, gelatinase granules and secondary granules using flow cytometry. We show that neutrophils during COVID-19 exhibit altered phenotypes compared to healthy individuals. The activation level including NETs production and maturity of neutrophils seem to last longer during COVID-19 than expected for innate immunity. Neutrophils as one of the drivers of severe cases of COVID-19 are considered as potential treatment targets. However, for a successful implementation of treatment, there is a need for a better understanding of neutrophil functions and phenotypes in COVID-19. Our study answers some of those questions.


Subject(s)
COVID-19 , Extracellular Traps , Extracellular Traps/metabolism , Flow Cytometry , Humans , Immunity, Innate , Inflammation/metabolism , Neutrophils/metabolism
11.
J Pharmacol Sci ; 150(1): 9-20, 2022 Sep.
Article in English | MEDLINE | ID: covidwho-1885946

ABSTRACT

In 2016, sepsis was newly defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Sepsis remains one of the crucial medical problems to be solved worldwide. Although the world health organization has made sepsis a global health priority, there remain no specific and effective therapy for sepsis so far. Indeed, over the previous decades almost all attempts to develop novel drugs have failed. This may be partly ascribable to the multifactorial complexity of the septic cascade and the resultant difficulties of identifying drug targets. In addition, there might still be missing links among dysregulated host responses in vital organs. In this review article, recent advances in understanding of the complex pathophysiology of sepsis are summarized, with a focus on neutrophil extracellular traps (NETs), the significant role of NETs in thrombosis/embolism, and the functional roles of plasma proteins, histidine-rich glycoprotein (HRG) and inter-alpha-inhibitor proteins (IAIPs). The specific plasma proteins that are markedly decreased in the acute phase of sepsis may play important roles in the regulation of blood cells, vascular endothelial cells and coagulation. The accumulating evidence may provide us with insights into a novel aspect of the pathophysiology of sepsis and septic ARDS, including that in COVID-19.


Subject(s)
COVID-19 , Extracellular Traps , Sepsis , Blood Proteins/metabolism , Endothelial Cells/metabolism , Extracellular Traps/metabolism , Glycoproteins/metabolism , Humans , Neutrophils
12.
Int J Mol Sci ; 22(19)2021 Sep 27.
Article in English | MEDLINE | ID: covidwho-1855649

ABSTRACT

The ocular surface is a gateway that contacts the outside and receives stimulation from the outside. The corneal innate immune system is composed of many types of cells, including epithelial cells, fibroblasts, natural killer cells, macrophages, neutrophils, dendritic cells, mast cells, basophils, eosinophils, mucin, and lysozyme. Neutrophil infiltration and degranulation occur on the ocular surface. Degranulation, neutrophil extracellular traps formation, called NETosis, and autophagy in neutrophils are involved in the pathogenesis of ocular surface diseases. It is necessary to understand the role of neutrophils on the ocular surface. Furthermore, there is a need for research on therapeutic agents targeting neutrophils and neutrophil extracellular trap formation for ocular surface diseases.


Subject(s)
Cell Degranulation , Cornea/metabolism , Extracellular Traps/metabolism , Eye Diseases/metabolism , Neutrophil Infiltration , Neutrophils/metabolism , Cornea/pathology , Eye Diseases/pathology , Humans , Neutrophils/pathology
13.
Int J Mol Sci ; 23(9)2022 Apr 27.
Article in English | MEDLINE | ID: covidwho-1809941

ABSTRACT

Neutrophil Extracellular Traps (NETs) are a contributing factor of vascular thrombosis and alveolar damage in COVID-19 patients. As enoxaparin is currently used to inhibit vascular thrombosis, this study aimed to investigate whether enoxaparin also reduced inflammation and NETs in COVID-19 patients. Patients with COVID-19 infection were classified into three groups: mild, moderate, and severe (n = 10 for all groups). Plasma was collected from patients and healthy donors (n = 10). Neutrophils isolated from healthy controls were incubated with COVID-19 or healthy plasma, and with or without enoxaparin pretreatment in vitro. Neutrophils and plasma isolated from patients treated with enoxaparin were also investigated. The levels of inflammatory cytokines and NET products such as dsDNA, NE, MPO-DNA and Histone-DNA complexes in plasma and supernatants were measured using immunofluorescence staining and ELISA kits. The expression of inflammatory signaling genes by neutrophils (RELA, SYK, ERK and PKC) was measured using real-time qPCR. The levels of NET products were elevated in the plasma of COVID-19 patients, particularly in the severe group (p < 0.01). Moreover, plasma from the severe group enhanced NET formation (p < 0.01) from neutrophils in vitro. Enoxaparin pretreatment in vitro decreased plasma-induced NETs in a dose-dependent manner and down-regulated the expression of inflammatory genes (p < 0.05). Patients treated with prophylactic enoxaparin showed lower inflammatory cytokine levels and expression of inflammatory genes (p < 0.05). Increased NETs were associated with the severity of COVID-19 infection, particularly in patients with severe pneumonia, and could be used as biomarkers to assess disease severity. Enoxaparin pretreatment inhibited NETs and reduced the expression of inflammatory cytokines, and these effects mostly persisted in patients treated with prophylactic enoxaparin.


Subject(s)
COVID-19 , Extracellular Traps , Thrombosis , Anti-Inflammatory Agents/pharmacology , COVID-19/drug therapy , Cytokines/metabolism , DNA/metabolism , Enoxaparin/pharmacology , Enoxaparin/therapeutic use , Extracellular Traps/metabolism , Humans , Neutrophils/metabolism , Thrombosis/drug therapy , Thrombosis/metabolism
14.
Int J Mol Sci ; 23(3)2022 Feb 05.
Article in English | MEDLINE | ID: covidwho-1674671

ABSTRACT

Inflammation and thrombosis are closely intertwined in numerous disorders, including ischemic events and sepsis, as well as coronavirus disease 2019 (COVID-19). Thrombotic complications are markers of disease severity in both sepsis and COVID-19 and are associated with multiorgan failure and increased mortality. Immunothrombosis is driven by the complement/tissue factor/neutrophil axis, as well as by activated platelets, which can trigger the release of neutrophil extracellular traps (NETs) and release further effectors of immunothrombosis, including platelet factor 4 (PF4/CXCL4) and high-mobility box 1 protein (HMGB1). Many of the central effectors of deregulated immunothrombosis, including activated platelets and platelet-derived extracellular vesicles (pEVs) expressing PF4, soluble PF4, HMGB1, histones, as well as histone-decorated NETs, are positively charged and thus bind to heparin. Here, we provide evidence that adsorbents functionalized with endpoint-attached heparin efficiently deplete activated platelets, pEVs, PF4, HMGB1 and histones/nucleosomes. We propose that this elimination of central effectors of immunothrombosis, rather than direct binding of pathogens, could be of clinical relevance for mitigating thrombotic complications in sepsis or COVID-19 using heparin-functionalized adsorbents.


Subject(s)
Blood Proteins/isolation & purification , Heparin/pharmacology , /drug therapy , Blood Coagulation/physiology , Blood Platelets/metabolism , Blood Proteins/metabolism , COVID-19/metabolism , Extracellular Traps/immunology , Extracellular Traps/metabolism , HMGB Proteins/isolation & purification , HMGB Proteins/metabolism , HMGB1 Protein/isolation & purification , HMGB1 Protein/metabolism , Heparin/metabolism , Histones/isolation & purification , Histones/metabolism , Humans , Neutrophils/metabolism , Platelet Activation/immunology , Platelet Factor 4/isolation & purification , Platelet Factor 4/metabolism , SARS-CoV-2/pathogenicity , Sepsis/blood , Sepsis/metabolism , Thromboplastin/metabolism , Thrombosis/drug therapy
15.
Int J Mol Sci ; 23(3)2022 Jan 29.
Article in English | MEDLINE | ID: covidwho-1667193

ABSTRACT

Elastin represents the structural component of the extracellular matrix providing elastic recoil to tissues such as skin, blood vessels and lungs. Elastogenic cells secrete soluble tropoelastin monomers into the extracellular space where these monomers associate with other matrix proteins (e.g., microfibrils and glycoproteins) and are crosslinked by lysyl oxidase to form insoluble fibres. Once elastic fibres are formed, they are very stable, highly resistant to degradation and have an almost negligible turnover. However, there are circumstances, mainly related to inflammatory conditions, where increased proteolytic degradation of elastic fibres may lead to consequences of major clinical relevance. In severely affected COVID-19 patients, for instance, the massive recruitment and activation of neutrophils is responsible for the profuse release of elastases and other proteolytic enzymes which cause the irreversible degradation of elastic fibres. Within the lungs, destruction of the elastic network may lead to the permanent impairment of pulmonary function, thus suggesting that elastases can be a promising target to preserve the elastic component in COVID-19 patients. Moreover, intrinsic and extrinsic factors additionally contributing to damaging the elastic component and to increasing the spread and severity of SARS-CoV-2 infection are reviewed.


Subject(s)
COVID-19/metabolism , Elastin/physiology , Extracellular Matrix/physiology , Animals , Elastic Tissue/metabolism , Elastin/metabolism , Extracellular Matrix Proteins/metabolism , Extracellular Traps/metabolism , Fibrillins/metabolism , Humans , Lung/pathology , Microfibrils/metabolism , Microfilament Proteins/metabolism , Neutrophils , Protein-Lysine 6-Oxidase/metabolism , SARS-CoV-2/pathogenicity , Tropoelastin/metabolism
16.
Cells ; 11(2)2022 01 06.
Article in English | MEDLINE | ID: covidwho-1613629

ABSTRACT

Neutrophil extracellular traps (NETs) are associated with multiple disease pathologies including sepsis, asthma, rheumatoid arthritis, cancer, systemic lupus erythematosus, acute respiratory distress syndrome, and COVID-19. NETs, being a disintegrated death form, suffered inconsistency in their identification, nomenclature, and quantifications that hindered therapeutic approaches using NETs as a target. Multiple strategies including microscopy, ELISA, immunoblotting, flow cytometry, and image-stream-based methods have exhibited drawbacks such as being subjective, non-specific, error-prone, and not being high throughput, and thus demand the development of innovative and efficient approaches for their analyses. Here, we established an imaging and computational algorithm using high content screening (HCS)-cellomics platform that aid in easy, rapid, and specific detection as well as analyses of NETs. This method employed membrane-permeable and impermeable DNA dyes in situ to identify NET-forming cells. Automated algorithm-driven single-cell analysis of change in nuclear morphology, increase in nuclear area, and change in intensities provided precise detection of NET-forming cells and eliminated user bias with other cell death modalities. Further combination with Annexin V staining in situ detected specific death pathway, e.g., apoptosis, and thus, discriminated between NETs, apoptosis, and necrosis. Our approach does not utilize fixation and permeabilization steps that disturb NETs, and thus, allows the time-dependent monitoring of NETs. Together, this specific imaging-based high throughput method for NETs analyses may provide a good platform for the discovery of potential inhibitors of NET formation and/or agents to modulate neutrophil death, e.g., NETosis-apoptosis switch, as an alternative strategy to enhance the resolution of inflammation.


Subject(s)
Algorithms , COVID-19/blood , Extracellular Traps/metabolism , Flow Cytometry , Neutrophils/metabolism , SARS-CoV-2/metabolism , Single-Cell Analysis , Humans
17.
Int Immunopharmacol ; 104: 108516, 2022 Mar.
Article in English | MEDLINE | ID: covidwho-1611782

ABSTRACT

Coronavirus disease 2019 (Covid-19) is a worldwide infectious disease caused by severe acute respiratory coronavirus 2 (SARS-CoV-2). In severe SARS-CoV-2 infection, there is severe inflammatory reactions due to neutrophil recruitments and infiltration in the different organs with the formation of neutrophil extracellular traps (NETs), which involved various complications of SARS-CoV-2 infection. Therefore, the objective of the present review was to explore the potential role of NETs in the pathogenesis of SARS-CoV-2 infection and to identify the targeting drugs against NETs in Covid-19 patients. Different enzyme types are involved in the formation of NETs, such as neutrophil elastase (NE), which degrades nuclear protein and release histones, peptidyl arginine deiminase type 4 (PADA4), which releases chromosomal DNA and gasdermin D, which creates pores in the NTs cell membrane that facilitating expulsion of NT contents. Despite of the beneficial effects of NETs in controlling of invading pathogens, sustained formations of NETs during respiratory viral infections are associated with collateral tissue injury. Excessive development of NETs in SARS-CoV-2 infection is linked with the development of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) due to creation of the NETs-IL-1ß loop. Also, aberrant NTs activation alone or through NETs formation may augment SARS-CoV-2-induced cytokine storm (CS) and macrophage activation syndrome (MAS) in patients with severe Covid-19. Furthermore, NETs formation in SARS-CoV-2 infection is associated with immuno-thrombosis and the development of ALI/ARDS. Therefore, anti-NETs therapy of natural or synthetic sources may mitigate SARS-CoV-2 infection-induced exaggerated immune response, hyperinflammation, immuno-thrombosis, and other complications.


Subject(s)
Acute Lung Injury/immunology , Anti-Inflammatory Agents/pharmacology , COVID-19/immunology , Cytokine Release Syndrome/immunology , Extracellular Traps/immunology , Acute Lung Injury/prevention & control , Acute Lung Injury/virology , Anti-Inflammatory Agents/therapeutic use , COVID-19/complications , COVID-19/drug therapy , COVID-19/virology , Cytokine Release Syndrome/prevention & control , Cytokine Release Syndrome/virology , Extracellular Traps/drug effects , Extracellular Traps/metabolism , Humans , Immunity, Innate/drug effects , Leukocyte Elastase/antagonists & inhibitors , Leukocyte Elastase/metabolism , Neutrophil Infiltration/drug effects , Phosphate-Binding Proteins/antagonists & inhibitors , Phosphate-Binding Proteins/metabolism , Pore Forming Cytotoxic Proteins/antagonists & inhibitors , Pore Forming Cytotoxic Proteins/metabolism , Protein-Arginine Deiminase Type 4/antagonists & inhibitors , Protein-Arginine Deiminase Type 4/metabolism , SARS-CoV-2/immunology
18.
Blood Adv ; 6(7): 2001-2013, 2022 04 12.
Article in English | MEDLINE | ID: covidwho-1603655

ABSTRACT

Infection by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) engages the inflammasome in monocytes and macrophages and leads to the cytokine storm in COVID-19. Neutrophils, the most abundant leukocytes, release neutrophil extracellular traps (NETs), which have been implicated in the pathogenesis of COVID-19. Our recent study shows that activation of the NLRP3 inflammasome is important for NET release in sterile inflammation. However, the role of neutrophil inflammasome formation in human disease is unknown. We hypothesized that SARS-CoV-2 infection may induce inflammasome activation in neutrophils. We also aimed to assess the localization of inflammasome formation (ie, apoptosis-associated speck-like protein containing a CARD [ASC] speck assembly) and timing relative to NETosis in stimulated neutrophils by real-time video microscopy. Neutrophils isolated from severe COVID-19 patients demonstrated that ∼2% of neutrophils in both the peripheral blood and tracheal aspirates presented ASC speck. ASC speck was observed in neutrophils with an intact poly-lobulated nucleus, suggesting early formation during neutrophil activation. Additionally, 40% of nuclei were positive for citrullinated histone H3, and there was a significant correlation between speck formation and nuclear histone citrullination. Time-lapse microscopy in lipopolysaccharide -stimulated neutrophils from fluorescent ASC reporter mice showed that ASC speck formed transiently and at the microtubule organizing center long before NET release. Our study shows that ASC speck is present in neutrophils from COVID-19 patients with respiratory failure and that it forms early in NETosis. Our findings suggest that inhibition of neutrophil inflammasomes may be beneficial in COVID-19.


Subject(s)
COVID-19 , Extracellular Traps , Animals , Extracellular Traps/metabolism , Humans , Inflammasomes/metabolism , Mice , Neutrophils/metabolism , SARS-CoV-2
19.
Sci Rep ; 11(1): 22463, 2021 11 17.
Article in English | MEDLINE | ID: covidwho-1592758

ABSTRACT

SARS-CoV-2 infection results in a spectrum of outcomes from no symptoms to widely varying degrees of illness to death. A better understanding of the immune response to SARS-CoV-2 infection and subsequent, often excessive, inflammation may inform treatment decisions and reveal opportunities for therapy. We studied immune cell subpopulations and their associations with clinical parameters in a cohort of 26 patients with COVID-19. Following informed consent, we collected blood samples from hospitalized patients with COVID-19 within 72 h of admission. Flow cytometry was used to analyze white blood cell subpopulations. Plasma levels of cytokines and chemokines were measured using ELISA. Neutrophils undergoing neutrophil extracellular traps (NET) formation were evaluated in blood smears. We examined the immunophenotype of patients with COVID-19 in comparison to that of SARS-CoV-2 negative controls. A novel subset of pro-inflammatory neutrophils expressing a high level of dual endothelin-1 and VEGF signal peptide-activated receptor (DEspR) at the cell surface was found to be associated with elevated circulating CCL23, increased NETosis, and critical-severity COVID-19 illness. The potential to target this subpopulation of neutrophils to reduce secondary tissue damage caused by SARS-CoV-2 infection warrants further investigation.


Subject(s)
COVID-19/immunology , Neutrophils/immunology , Pseudogenes/immunology , Aged , Chemokines/metabolism , Cohort Studies , Critical Illness , Cytokines/metabolism , Enzyme-Linked Immunosorbent Assay/methods , Extracellular Traps/metabolism , Female , Humans , Inflammation/metabolism , Male , Middle Aged , Neutrophils/metabolism , Pseudogenes/genetics , SARS-CoV-2/immunology , SARS-CoV-2/pathogenicity , Severity of Illness Index
20.
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
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