Immunopathological mechanisms in sepsis of viral etiology in COVID-19.

The article provides information on immunopathology in sepsis and the commonality between immunopathogenetic processes of sepsis and the new coronavirus infection (COVID-19). As a result of the inability of the immune system to cope with aggression of the pathogen, inadequate immune activity occurs manifested by the systemic inflammatory response syndrome, resulting in damage to tissues of the host organism. In response, compensatory anti-inflammatory response syndrome is activated, which is manifested by inhibition of the immune response. One of its main mechanisms is signals produced by membrane receptors and their ligands. Against the background of inability of the host organism to neutralise the pathogen, numerous pathological phenomena and complications occur leading to damage to human tissues.Copyright © 2021, Krasnoyarsk State Medical University. All rights reserved.

Exploration of potential mechanism of SARS-CoV-2 induced immune inflammatory response leading to progression of atherosclerosis and prediction of traditional Chinese medicine for preventing and treating based on bioinformatics.

Objective To explore the core targets and important pathways of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) induced atherosclerosis (AS) progression from the perspective of immune inflammation, so as to predict the potential prevention and treatment of traditional Chinese medicine (TCM). Methods Microarray data were obtained from the Gene Expression Omnibus (GEO) database for coronavirus disease 2019 (COVID-19) patients and AS patients, and the "limmar" and "Venn" packages were used to screen out the common differentially expressed genes (DEGs) genes in both diseases. The gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) analyses were performed on the common DEGs to annotate their functions and important pathways. The two gene sets were scored for immune cells and immune function to assess the level of immune cell infiltration. The protein-protein interaction (PPI) network was constructed by STRING database, and the CytoHubba plug-in of Cytoscape was used to identify the hub genes. Two external validation datasets were introduced to validate the hub genes and obtain the core genes. Immuno-infiltration analysis and gene set enrichment analysis (GSEA) were performed on the core genes respectively. Finally the potential TCM regulating the core genes were predicted by Coremine Medical database. Results A total of 7898 genes related to COVID-19, 471 genes related to AS progression;And 51 common DEGs, including 32 highly expressed genes and 19 low expressed genes were obtained. GO and KEGG analysis showed that common DEGs, which were mainly localized in cypermethrin-encapsulated vesicles, platelet alpha particles, phagocytic vesicle membranes and vesicles, were involved in many biological processes such as myeloid differentiation factor 88 (MyD88)-dependent Toll-like receptor signaling pathway transduction, interleukin-8 (IL-8) production and positive regulation, IL-6 production and positive regulation to play a role in regulating nicotinamide adenine dinucleotide phosphate oxidase activity, Toll-like receptor binding and lipopeptide and glycosaminoglycan binding through many biological pathways, including Toll-like receptor signaling pathways, neutrophil extracellular trap formation, complement and coagulation cascade reactions. The results of immune infiltration analysis demonstrated the state of immune microenvironment of COVID-19 and AS. A total of 5 hub genes were obtained after screening, among which Toll-like receptor 2 (TLR2), cluster of differentiation 163 (CD163) and complement C1q subcomponent subunit B (C1QB) genes passed external validation as core genes. The core genes showed strong correlation with immune process and inflammatory response in both immune infiltration analysis and GSEA enrichment analysis. A total of 35 TCMs, including Chuanxiong (Chuanxiong Rhizoma), Taoren (Persicae Semen), Danggui (Angelicae Sinensis Radix), Huangqin (Scutellariae Radix), Pugongying (Taraxaci Herba), Taizishen (Pseudostellariae Radix), Huangjing (Polygonati Rhizoma), could be used as potential therapeutic agents. Conclusion TLR2, CD163 and C1QB were the core molecules of SARS-CoV-2-mediated immune inflammatory response promoting AS progression, and targeting predicted herbs were potential drugs to slow down AS progression in COVID-19 patients.Copyright © 2023 Editorial Office of Chinese Traditional and Herbal Drugs. All rights reserved.

2C5-surface modified nanocarriers targeting neutrophil extracellular traps

Background: Neutrophil extracellular traps (NETs) are composed of processed chromatin bound to granular and selected cytoplasmic proteins and released by neutrophils. NETs consist of smooth filaments composed of stacked nucleosomes. Fully hydrated NETs have a cloud-like appearance and occupy a space 10-15-fold larger than the volume of the cells they originate from. DNases are the enzymes that cleave extracellular DNA including NETs. Together with their protective role in microbial infections, NETs are involved in multiple pathological processes and represent key events in a variety of pathologies including cancer, autoimmunity, and cardiovascular disease. Sites of NETs concentration are dangerous for the host if the process of NETs formation becomes chronic or the mechanism of NETs removal does not work. NETosis has been linked to the development of periodontitis, cystic fibrosis, type 2 diabetes, COVID-19 or rheumatoid arthritis as well as cancer progression. Purpose(s): Thus, the destruction of NETs is of primary significance in many pathologies. In our approach, we are focusing on mimicking one of the natural mechanisms of destroying excessive NETs by delivering deoxyribonuclease I to the specific site of pathological NETs accumulation by modifying the nanoparticles using an anti-nucleosome monoclonal antibody (2C5). The antibody is specific to nucleosomes and can recognize histones in NETs. DNase I is U.S. Food and Drug Administration (FDA)-approved active component and is commonly used in therapeutic methods of modern medicine for cystic fibrosis to clear extracellular DNA fibers in the lungs and systemic lupus erythematosus. Recent findings have also shown the effectiveness of DNase I in the digestion of NETs. However, the low serum stability and fast deactivation by environmental stimuli have been considered as the limiting factors for clinical applications of DNase I, which can be overcome by its targeted specific delivery in pharmaceutical nanocarriers. Method(s): In this study, we generate NETs in vitro using human neutrophils and HL-60 cells differentiated into granulocyte-like cells. We used interleukin-8, lipopolysaccharide from E.Coli (LPS), phorbol myristate acetate (PMA), and calcium ionophore A23187 (CI) to generate the NETs. We confirmed the specificity of 2C5 toward NETs by ELISA, which showed that it binds to NETs with the specificity like that for purified nucleohistone substrate. We further utilized that feature to create two delivery systems (liposomes and micelles) for DNAse I enzyme to destroy NETs, which was confirmed by staining NETs with SYTOX Green dye and followed by flow cytometric measurements and microscopic images. Conclusion(s): Our results suggest that 2C5 could be used to identify and visualize NETs and serve as a ligand for NET-targeted diagnostics and therapies. Also, we proved that our carrier can successfully deliver DNase to NETs to provide their degradation.

NETosis in Parasitic Infections: A Puzzle That Remains Unsolved.

Neutrophils are the key players in the innate immune system, being weaponized with numerous strategies to eliminate pathogens. The production of extracellular traps is one of the effector mechanisms operated by neutrophils in a process called NETosis. Neutrophil extracellular traps (NETs) are complex webs of extracellular DNA studded with histones and cytoplasmic granular proteins. Since their first description in 2004, NETs have been widely investigated in different infectious processes. Bacteria, viruses, and fungi have been shown to induce the generation of NETs. Knowledge is only beginning to emerge about the participation of DNA webs in the host's battle against parasitic infections. Referring to helminthic infections, we ought to look beyond the scope of confining the roles of NETs solely to parasitic ensnarement or immobilization. Hence, this review provides detailed insights into the less-explored activities of NETs against invading helminths. In addition, most of the studies that have addressed the implications of NETs in protozoan infections have chiefly focused on their protective side, either through trapping or killing. Challenging this belief, we propose several limitations regarding protozoan-NETs interaction. One of many is the duality in the functional responses of NETs, in which both the positive and pathological aspects seem to be closely intertwined.

NETosis as an oncologic therapeutic target: a mini review.

Neutrophil Extracellular Traps (NETs) are a key form of pro-inflammatory cell death of neutrophils characterized by the extrusion of extracellular webs of DNA containing bactericidal killing enzymes. NETosis is heavily implicated as a key driver of host damage in autoimmune diseases where injurious release of proinflammatory enzymes damage surrounding tissue and releases 70 known autoantigens. Recent evidence shows that both neutrophils and NETosis have a role to play in carcinogenesis, both indirectly through triggering DNA damage through inflammation, and directly contributing to a pro-tumorigenic tumor microenvironment. In this mini-review, we summarize the current knowledge of the various mechanisms of interaction and influence between neutrophils, with particular attention to NETosis, and cancer cells. We will also highlight the potential avenues thus far explored where we can intercept these processes, with the aim of identifying promising prospective targets in cancer treatment to be explored in further studies.

The Role of NETosis and Complement Activation in COVID-19-Associated Coagulopathies.

Inflammation-induced coagulopathy is a common complication associated with coronavirus disease 2019 (COVID-19). We aim to evaluate the association of NETosis and complement markers with each other as well as their association with thrombogenicity and disease severity in COVID-19. The study included hospitalized patients with an acute respiratory infection: patients with SARS-CoV2 infection (COVpos, n = 47) or either pneumonia or infection-triggered acute exacerbated COPD (COVneg, n = 36). Our results show that NETosis, coagulation, and platelets, as well as complement markers, were significantly increased in COVpos patients, especially in severely ill COVpos patients. NETosis marker MPO/DNA complexes correlated with coagulation, platelet, and complement markers only in COVpos. Severely ill COVpos patients showed an association between complement C3 and SOFA (R = 0.48; p ≤ 0.028), C5 and SOFA (R = 0.46; p ≤ 0.038), and C5b-9 and SOFA (R = 0.44; p ≤ 0.046). This study provides further evidence that NETosis and the complement system are key players in COVID-19 inflammation and clinical severity. Unlike previous studies that found NETosis and complement markers to be elevated in COVID-19 patients compared to healthy controls, our findings show that this characteristic distinguishes COVID-19 from other pulmonary infectious diseases. Based on our results, we propose that COVID-19 patients at high risk for immunothrombosis could be identified via elevated complement markers such as C5.

A Brief Overview of Neutrophils in Neurological Diseases.

Neutrophils are the most abundant leukocyte in circulation and are the first line of defense after an infection or injury. Neutrophils have a broad spectrum of functions, including phagocytosis of microorganisms, the release of pro-inflammatory cytokines and chemokines, oxidative burst, and the formation of neutrophil extracellular traps. Traditionally, neutrophils were thought to be most important for acute inflammatory responses, with a short half-life and a more static response to infections and injury. However, this view has changed in recent years showing neutrophil heterogeneity and dynamics, indicating a much more regulated and flexible response. Here we will discuss the role of neutrophils in aging and neurological disorders; specifically, we focus on recent data indicating the impact of neutrophils in chronic inflammatory processes and their contribution to neurological diseases. Lastly, we aim to conclude that reactive neutrophils directly contribute to increased vascular inflammation and age-related diseases.

Features of inflammatory periodontal diseases course in combination with a new coronavirus disease. A systematic review

Risk factors for severe COVID-19 are also associated with periodontitis. They are smoking, older age, obesity, diabetes mellitus, hypertension and cardiovascular diseases. The aim of the study was to select and analyze publications that consider a possible relationship between inflammatory periodontal diseases and the severity of COVID-19. Material and methods. The search for publications by the key words was conducted using the electronic databases: Cochrane Library;MEDLINE, eLIBRARY for systematic review. We selected 94 publications, the systematic review included 10 scientific articles presenting the results of randomized trials. Results. The results of the analysis showed the connection between COVID-19 severity and inflammatory periodontal diseases presence. In the patients with severe COVID-19 on the background of periodontitis it was established a high risk for artificial lung ventilation prescription. The course of COVID-19 is possibly depending on high expression of ACE2 receptors in oral mucosal cells and aspiration of pathogenic bacteria from periodontal tissues with saliva on the background of SARS-CoV-2 viral infection. The bacterial etiology of periodontitis plays important role of an immunological trigger that causes hyperreaction of humoral and cellular immunity, NETosis activation and NLRP3 inflammation. Conclusion. The presence of periodontitis in patients with overweight and obesity, DM or hypertension may be associated with severe COVID-19 course, possible development of complications and pneumonia.Copyright © Eco-Vector, 2023. All rights reserved.

Therapeutic approaches for intravascular microthrombi-induced acute respiratory distress syndrome (ARDS) in COVID-19 infection.

The COVID-19 pandemic has overwhelmed our health care capacity in an unprecedented way due to the sheer number of critically infected patients admitted to hospitals during the last two years. Endothelial injury is seen as one of the central hallmarks of COVID-19 infection that is the starting point in the generation of microthrombi and sepsis eventually leading to acute respiratory distress syndrome (ARDs) and multi-organ failure. The dramatic fall in lung function during ARDs is attributed to the microthrombi-induced coagulopathy primed by a hyperactive immune system. Due to the lack of effective antiviral agents, the line of treatment is limited to the management of two key risk factors i.e., immune activation and coagulopathy. In the present review, we describe the mechanistic role, therapeutic targets and opportunities to control immune activation and coagulopathy during the pathogenesis of COVID-19-induced ARDs.

THE ROLE OF NEUTROPHIL EXTRACELLULAR TRAPS (NETs) IN THE IMMUNOPATHOGENESIS OF SEVERE COVID-19: POTENTIAL IMMUNOTHERAPEUTIC STRATEGIES REGULATING NET FORMATION AND ACTIVITY.

The role of neutrophil granulocytes (NG) in the pathogenesis of COVID-19 is associated with the NG recruitment into inflammatory foci, activation of their functions and enhanced formation of neutrophil extracellular networks (NETs). In this review, we analyzed a large body of scientific literature devoted to the features of developing NETs, their role in the COVID-19 pathogenesis, a role in emerging immunothrombosis, vasculitis, acute respiratory distress syndrome, cytokine storm syndrome, and multi-organ lesions. Convincing data are presented clearly indicating about a profound role of NETs in the COVID-19 immunopathogenesis and associated severe complications resulting from intensified inflammation process, which is a key for the course of SARS-CoV-2 virus infection. The presented role of NGs and NETs, along with that of other immune system cells and pro-inflammatory cytokines, is extremely important in understanding development of overactive immune response in severe COVID-19. The scientific results obtained available now allow to identify an opportunity of regulatory effects on hyperactivated NGs, NETosis at various stages and on limiting a negative impact of pre-formed NETs on various tissues and organs. All the aforementioned data should help in creating new, specialized immunotherapy strategies designed to increase the odds of survival, reduce severity of clinical manifestations in COVID-19 patients as well as markedly reduce mortality rates. Currently, it is possible to use existing drugs, while a number of new drugs are being developed, the action of which can regulate NG quantity, positively affect NG functions and limit intensity of NETosis. Continuing research on the role of hyperactive NG and NETosis as well as understanding the mechanisms of regulating NET formation and restriction in severe COVID-19, apparently, are of high priority, because in the future the new data obtained could pave the basis for development of targeted approaches not only for immunotherapy aimed at limiting education and blocking negative effects already formed NETs in severe COVID-19, but also for immunotherapy, which could be used in combination treatment of other netopathies, primarily autoimmune diseases, auto-inflammatory syndromes, severe purulent-inflammatory processes, including bacterial sepsis and hematogenous osteomyelitis.Copyright © 2023 Saint Petersburg Pasteur Institute. All rights reserved.

DNase analysed by a novel competitive assay in patients with complications after ChAdOx1 nCoV-19 vaccination and in normal unvaccinated blood donors

Increased levels of neutrophil extracellular traps (NETs) have been detected in individuals with vaccine complications after the ChAdOx1 nCov vaccine with a correlation between the severity of vaccine side effects and the level of NETosis. DNases may disrupt NETs by degrading their content of DNA, and a balance has been reported between NETs and DNases. Because of this and since the inflammatory marker NETs may be used as a confirmatory test in diagnosing VITT, it is of interest to monitor levels of DNase in patients with increased NETs levels. The current novel rapid DNase ELISA was tested in blood samples of patients with known increased levels of NETs with or without VITT after ChAdOx1 nCoV-19 vaccination. DNase levels in VITT patients were significantly increased compared with normal unvaccinated blood donors and compared with patients with post-vaccination symptoms but not VITT. However, since EDTA was found to inhibit DNase, serum and not EDTA-plasma samples should be applied for DNase testing. The novel DNase assay may serve as a supplementary test to the NETs test when analysing samples from patients with suspected increased NETs levels.Copyright © 2023 The Scandinavian Foundation for Immunology.

Features of inflammatory periodontal diseases course in combination with a new coronavirus disease. A systematic review.

Risk factors for severe COVID-19 are also associated with periodontitis. They are smoking, older age, obesity, diabetes mellitus, hypertension and cardiovascular diseases. The aim of the study was to select and analyze publications that consider a possible relationship between inflammatory periodontal diseases and the severity of COVID-19. Material and methods. The search for publications by the key words was conducted using the electronic databases: Cochrane Library;MEDLINE, eLIBRARY for systematic review. We selected 94 publications, the systematic review included 10 scientific articles presenting the results of randomized trials. Results. The results of the analysis showed the connection between COVID-19 severity and inflammatory periodontal diseases presence. In the patients with severe COVID-19 on the background of periodontitis it was established a high risk for artificial lung ventilation prescription. The course of COVID-19 is possibly depending on high expression of ACE2 receptors in oral mucosal cells and aspiration of pathogenic bacteria from periodontal tissues with saliva on the background of SARS-CoV-2 viral infection. The bacterial etiology of periodontitis plays important role of an immunological trigger that causes hyperreaction of humoral and cellular immunity, NETosis activation and NLRP3 inflammation. Conclusion. The presence of periodontitis in patients with overweight and obesity, DM or hypertension may be associated with severe COVID-19 course, possible development of complications and pneumonia.Copyright © Eco-Vector, 2023. All rights reserved.

Direct blood fluorescence signal intensity of neutrophils (NEU-SFL): A predictive marker of death in hospitalized COVID-19 patients?

Introduction: Coronavirus disease 2019 (COVID-19) is a respiratory disease triggered by immunopathological mechanisms that cause excessive inflammation and leukocyte dysfunction. Neutrophils play a critical role in the innate immunity and are able to produce neutrophil extracellular traps (NETs: NETosis process) to combat infections. Some NETs markers are increased in patients who died from COVID-19. Recently, the neutrophil fluorescence variable (NEU-SFL), available on certain automated complete blood count (CBC) analyzers, has been correlated with NET formation and may reflect NETosis in patients. Here we evaluate whether NEU-SFL measured after admission of COVID-19 patients is associated with in-hospital survival or death. Patients and methods: 1,852 patients admitted for severe COVID-19 at Nîmes University Hospital in 2021 were retrospectively included in the study: 1,564 who survived the hospital stay and 288 who did not. The NEU-SFL was obtained on the Sysmex™ XN-10® analyzer and values for survivors and non-survivors were compared. The intra-patient NEU-SFL variations between the hospital entry and the last day of hospitalization were also analyzed (IRB 22.06.01, NCT05413824). Results: Non-survivors presented higher NEU-SFL values. NEU-SFL values above the 4th quartile were independently associated with a 2.88-fold risk of death. Furthermore, the difference of NEU-SFL values between the first and the last available data during hospitalization revealed that a decrease in NEU-SFL was associated to survivors and vice versa. Conclusion: Our study reinforces the role of neutrophils and NETosis in the pathophysiology and prognosis of COVID-19. Further studies combining NEU-SFL with other NETosis markers could improve the management of COVID-19 patients.

COVID-19 neutrophils show elevated migration and NETosis, which is reduced by PI3K inhibition

Rational: Evidence of neutrophil dysfunction in COVID-19 is based on transcriptomics. Cell functions are interwoven pathways, so understanding the effect of COVID-19 across neutrophil function may identify therapeutic targets. We examined neutrophil phenotype and function in 41 hospitalised, non-ICU COVID-19 patients versus 23 age-matched controls (AMC) and 26 community acquired pneumonia (CAP) patients. Method(s): Isolated neutrophils underwent ex vivo analyses for migration, phagocytosis and NETosis, and the effect of PI3K inhibition. Circulating DNAse 1 activity and levels of cfDNA were measured. Result(s): Compared to AMC and CAP, COVID-19 neutrophils demonstrated elevated transmigration (p=0.0397, A) and NETosis (p=0.0366, B), but impaired phagocytosis (p=0.0236, C) associated with impaired ROS generation (p<0.0001). COVID-19 and CAP patients showed increased systemic markers of NETosis including increased cfDNA (p=0.0153) and impaired DNAse activity (p<0.0.001, D). Ex vivo inhibition of PI3K gamma and delta reduced NET release by COVID-19 neutrophils (p=0.0156). Conclusion(s): COVID-19 is associated with neutrophil dysfunction across all main effector functions, with elevated migration, impaired antimicrobial responses and elevated NETosis. These changes represent a clear mechanism for tissue damage and highlight that targeting neutrophil function via PI3k may help modulate COVID-19 severity. (Figure Presented).

Covid-19 and NETs

Introduction: Neutrophil extracellular traps (NETs) have recently been linked to an important role in the pathogenesis of Covid-19. Method(s): Prospective observational study of 91 hospitalized patients. We studied longitudinally the viral phase, early inflammatory and late, and the 4 most specific components of NETs: cell free-DNA (cfDNA), MPO-DNA and NE-DNA complexes and citrullinated Histone 3 (citH3). Result(s): We observed elevated levels vs controls of MPO-DNA and NE-DNA complexes and cfDNA at admission and in the 3 phases of the disease. CitH3 was elevated from the early inflammatory phase onwards. There was a significant correlation in survivors (r=0.798) and in all severity degrees between MPO and NE and between cfDNA and H3 cit (r=0.3), but not in the rest of combinations among the 4, nor in dead patients. We did not observe any correlation in any group between MPO or NE with citH3. There was an increase of only cfDNA levels in more severe patients. The area under the ROC curve for critical severity and mortality was high for cfDNA (0.7327 and 0.7482) and much poorer for the other 3 NETs markers. Conclusion(s): -We found evidence of neutrophil activation of NETs components in Covid-19, during the 3 phases of the disease, but without a clear relationship with severity and mortality. -cfDNA was related to severity and mortality, and its sources appeared to be more related to tissue damage than to NETs -The best correlation between them was MPO-NE, and these more neutrophil-specific markers reflect probably better NET formation. NETs role has maybe been overestimated using other less specific markers.

Innate immune responses in COVID-19

Innate immunity is the first line of host defense against microbes, including SARS-CoV-2. This pleiotropic immunological mechanism is initiated within minutes to hours after infection. Here, we summarize innate immune processes involved in SARS-CoV-2 recognition, cellular, and molecular response including inflammation, as well as the related immune modulatory therapies that have been evaluated in clinical trials for COVID-19. Innate immune responses limit viral replication, help identify and remove infected cells, sense pathogen-associated molecular patterns, trigger signaling pathways, inflammatory responses, cytokine production, programmed cell death, and contribute the development of adaptive immunity. Excessive activation of the host innate immune response is associated with severe disease and death. The availability and speed of implementation of these mechanisms in infected individuals may explain in part the heterogeneous disease spectrum and courses observed in patients. © 2023 Elsevier Inc. All rights reserved.

Tissue injury and leukocyte changes in post-acute sequelae of SARS-CoV-2: review of 2833 post-acute patient outcomes per immune dysregulation and microbial translocation in long COVID.

A significant number of persons with coronavirus disease 2019 (COVID-19) experience persistent, recurrent, or new symptoms several months after the acute stage of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. This phenomenon, termed post-acute sequelae of SARS-CoV-2 (PASC) or long COVID, is associated with high viral titers during acute infection, a persistently hyperactivated immune system, tissue injury by NETosis-induced micro-thrombofibrosis (NETinjury), microbial translocation, complement deposition, fibrotic macrophages, the presence of autoantibodies, and lymphopenic immune environments. Here, we review the current literature on the immunological imbalances that occur during PASC. Specifically, we focus on data supporting common immunopathogenesis and tissue injury mechanisms shared across this highly heterogenous disorder, including NETosis, coagulopathy, and fibrosis. Mechanisms include changes in leukocyte subsets/functions, fibroblast activation, cytokine imbalances, lower cortisol, autoantibodies, co-pathogen reactivation, and residual immune activation driven by persistent viral antigens and/or microbial translocation. Taken together, we develop the premise that SARS-CoV-2 infection results in PASC as a consequence of acute and/or persistent single or multiple organ injury mediated by PASC determinants to include the degree of host responses (inflammation, NETinjury), residual viral antigen (persistent antigen), and exogenous factors (microbial translocation). Determinants of PASC may be amplified by comorbidities, age, and sex.

Autophagy in Inflammatory Response against SARS-CoV-2.

The coronavirus disease pandemic, which profoundly reshaped the world in 2019 (COVID-19), and is currently ongoing, has affected over 200 countries, caused over 500 million cumulative cases, and claimed the lives of over 6.4 million people worldwide as of August 2022. The causative agent is severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Depicting this virus' life cycle and pathogenic mechanisms, as well as the cellular host factors and pathways involved during infection, has great relevance for the development of therapeutic strategies. Autophagy is a catabolic process that sequesters damaged cell organelles, proteins, and external invading microbes, and delivers them to the lysosomes for degradation. Autophagy would be involved in the entry, endo, and release, as well as the transcription and translation, of the viral particles in the host cell. Secretory autophagy would also be involved in developing the thrombotic immune-inflammatory syndrome seen in a significant number of COVID-19 patients that can lead to severe illness and even death. This review aims to review the main aspects that characterize the complex and not yet fully elucidated relationship between SARS-CoV-2 infection and autophagy. It briefly describes the key concepts regarding autophagy and mentions its pro- and antiviral roles, while also noting the reciprocal effect of viral infection in autophagic pathways and their clinical aspects.

Novel mechanisms of thrombo-inflammation during infection: spotlight on neutrophil extracellular trap-mediated platelet activation.

A state-of-the-art lecture titled "novel mechanisms of thrombo-inflammation during infection" was presented at the ISTH Congress in 2022. Platelet, neutrophil, and endothelial cell activation coordinate the development, progression, and resolution of thrombo-inflammatory events during infection. Activated platelets and neutrophil extracellular traps (NETs) are frequently observed in patients with sepsis and COVID-19, and high levels of NET-derived damage-associated molecular patterns (DAMPs) correlate with thrombotic complications. NET-associated DAMPs induce direct and indirect platelet activation, which in return potentiates neutrophil activation and NET formation. These coordinated interactions involve multiple receptors and signaling pathways contributing to vascular and organ damage exacerbating disease severity. This state-of-the-art review describes the main mechanisms by which platelets support NETosis and the key mechanisms by which NET-derived DAMPs trigger platelet activation and the formation of procoagulant platelets leading to thrombosis. We report how these DAMPs act through multiple receptors and signaling pathways differentially regulating cell activation and disease outcome, focusing on histones and S100A8/A9 and their contribution to the pathogenesis of sepsis and COVID-19. We further discuss the complexity of platelet activation during NETosis and the potential benefit of targeting selective or multiple NET-associated DAMPs to limit thrombo-inflammation during infection. Finally, we summarize relevant new data on this topic presented during the 2022 ISTH Congress.