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1.
Front Immunol ; 12: 792448, 2021.
Article in English | MEDLINE | ID: covidwho-1581318

ABSTRACT

Both severe SARS-CoV-2 infections and bacterial sepsis exhibit an immunological dyscrasia and propensity for secondary infections. The nature of the immunological dyscrasias for these differing etiologies and their time course remain unclear. In this study, thirty hospitalized patients with SARS-CoV-2 infection were compared with ten critically ill patients with bacterial sepsis over 21 days, as well as ten healthy control subjects. Blood was sampled between days 1 and 21 after admission for targeted plasma biomarker analysis, cellular phenotyping, and leukocyte functional analysis via enzyme-linked immunospot assay. We found that circulating inflammatory markers were significantly higher early after bacterial sepsis compared with SARS-CoV-2. Both cohorts exhibited profound immune suppression through 21 days (suppressed HLA-DR expression, reduced mononuclear cell IFN-gamma production), and expanded numbers of myeloid-derived suppressor cells (MDSCs). In addition, MDSC expansion and ex vivo production of IFN-gamma and TNF-alpha were resolving over time in bacterial sepsis, whereas in SARS-CoV-2, immunosuppression and inflammation were accelerating. Despite less severe initial physiologic derangement, SARS-CoV-2 patients had similar incidence of secondary infections (23% vs 30%) as bacterial sepsis patients. Finally, COVID patients who developed secondary bacterial infections exhibited profound immunosuppression evident by elevated sPD-L1 and depressed HLA-DR. Although both bacterial sepsis and SARS-CoV-2 are associated with inflammation and immune suppression, their immune dyscrasia temporal patterns and clinical outcomes are different. SARS-CoV-2 patients had less severe early inflammation and organ dysfunction but had persistent inflammation and immunosuppression and suffered worse clinical outcomes, especially when SARS-CoV-2 infection was followed by secondary bacterial infection.


Subject(s)
Bacterial Infections/immunology , COVID-19/immunology , Immune Tolerance/immunology , Sepsis/immunology , Adult , Aged , Female , Humans , Male , Middle Aged , Prospective Studies , SARS-CoV-2
2.
Antioxid Redox Signal ; 35(16): 1376-1392, 2021 12.
Article in English | MEDLINE | ID: covidwho-1510864

ABSTRACT

Significance: It is estimated that close to 50 million cases of sepsis result in over 11 million annual fatalities worldwide. The pathognomonic feature of sepsis is a dysregulated inflammatory response arising from viral, bacterial, or fungal infections. Immune recognition of pathogen-associated molecular patterns is a hallmark of the host immune defense to combat microbes and to prevent the progression to sepsis. Mitochondrial antiviral signaling protein (MAVS) is a ubiquitous adaptor protein located at the outer mitochondrial membrane, which is activated by the cytosolic pattern recognition receptors, retinoic acid-inducible gene I (RIG-I) and melanoma differentiation associated gene 5 (MDA5), following binding of viral RNA agonists. Recent Advances: Substantial progress has been made in deciphering the activation of the MAVS pathway with its interacting proteins, downstream signaling events (interferon [IFN] regulatory factors, nuclear factor kappa B), and context-dependent type I/III IFN response. Critical Issues: In the evolutionary race between pathogens and the host, viruses have developed immune evasion strategies for cleavage, degradation, or blockade of proteins in the MAVS pathway. For example, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) M protein and ORF9b protein antagonize MAVS signaling and a protective type I IFN response. Future Directions: The role of MAVS as a sensor for nonviral pathogens, host cell injury, and metabolic perturbations awaits better characterization in the future. New technical advances in multidimensional single-cell analysis and single-molecule methods will accelerate the rate of new discoveries. The ultimate goal is to manipulate MAVS activities in the form of immune-modulatory therapies to combat infections and sepsis. Antioxid. Redox Signal. 35, 1376-1392.


Subject(s)
Adaptor Proteins, Signal Transducing/immunology , Sepsis/immunology , Signal Transduction/immunology , Virus Diseases/immunology , Animals , Host-Pathogen Interactions/immunology , Humans , Immune Evasion/immunology , Sepsis/virology
3.
J Immunol ; 207(7): 1776-1784, 2021 10 01.
Article in English | MEDLINE | ID: covidwho-1497460

ABSTRACT

Acquired neutrophil dysfunction frequently develops during critical illness, independently increasing the risk for intensive care unit-acquired infection. PI3Kδ is implicated in driving neutrophil dysfunction and can potentially be targeted pharmacologically. The aims of this study were to determine whether PI3Kδ inhibition reverses dysfunction in neutrophils from critically ill patients and to describe potential mechanisms. Neutrophils were isolated from blood taken from critically ill patients requiring intubation and mechanical ventilation, renal support, or blood pressure support. In separate validation experiments, neutrophil dysfunction was induced pharmacologically in neutrophils from healthy volunteers. Phagocytosis and bacterial killing assays were performed, and activity of RhoA and protein kinase A (PKA) was assessed. Inhibitors of PI3Kδ, 3-phosphoinositide-dependent protein kinase-1 (PDK1), and PKA were used to determine mechanisms of neutrophil dysfunction. Sixty-six patients were recruited. In the 27 patients (40.9%) with impaired neutrophil function, PI3Kδ inhibition consistently improved function and significantly increased bacterial killing. These findings were validated in neutrophils from healthy volunteers with salbutamol-induced dysfunction and extended to demonstrate that PI3Kδ inhibition restored killing of clinical isolates of nine pathogens commonly associated with intensive care unit-acquired infection. PI3Kδ activation was associated with PDK1 activation, which in turn phosphorylated PKA, which drove phosphorylation and inhibition of the key regulator of neutrophil phagocytosis, RhoA. These data indicate that, in a significant proportion of critically ill patients, PI3Kδ inhibition can improve neutrophil function through PDK1- and PKA-dependent processes, suggesting that therapeutic use of PI3Kδ inhibitors warrants investigation in this setting.


Subject(s)
COVID-19/immunology , Class I Phosphatidylinositol 3-Kinases/metabolism , Critical Illness , Neutrophils/immunology , Pneumonia/immunology , SARS-CoV-2/physiology , Sepsis/immunology , 3-Phosphoinositide-Dependent Protein Kinases/pharmacology , Adult , Aged , Aged, 80 and over , Bacterial Load , Bacteriolysis , Cells, Cultured , Cyclic AMP-Dependent Protein Kinases/metabolism , Female , Humans , Male , Middle Aged , Phagocytosis , Phosphoinositide-3 Kinase Inhibitors/pharmacology , Respiratory Insufficiency , Risk
4.
Cells ; 10(10)2021 10 05.
Article in English | MEDLINE | ID: covidwho-1458308

ABSTRACT

Extracellular vesicles (EVs) have been identified as novel mediators of intercellular communication. They work via delivering the sequestered cargo to cells in the close vicinity, as well as distant sites in the body, regulating pathophysiological processes. Cell death and inflammation are biologically crucial processes in both normal physiology and pathology. These processes are indistinguishably linked with their effectors modulating the other process. For instance, during an unresolvable infection, the upregulation of specific immune mediators leads to inflammation causing cell death and tissue damage. EVs have gained considerable interest as mediators of both cell death and inflammation during conditions, such as sepsis. This review summarizes the types of extracellular vesicles known to date and their roles in mediating immune responses leading to cell death and inflammation with specific focus on sepsis and lung inflammation.


Subject(s)
Apoptosis , COVID-19/therapy , Cell Death , Extracellular Vesicles/metabolism , Inflammation/metabolism , Lung/pathology , SARS-CoV-2 , Sepsis/immunology , Animals , Biomarkers/metabolism , COVID-19/immunology , Cell Communication , Chemokines , Exosomes , Humans , Lung/immunology , Mice , Sepsis/physiopathology
5.
Front Immunol ; 12: 744799, 2021.
Article in English | MEDLINE | ID: covidwho-1448731

ABSTRACT

Sepsis is a global health emergency, which is caused by various sources of infection that lead to changes in gene expression, protein-coding, and metabolism. Advancements in "omics" technologies have provided valuable tools to unravel the mechanisms involved in the pathogenesis of this disease. In this study, we performed shotgun mass spectrometry in peripheral blood mononuclear cells (PBMC) from septic patients (N=24) and healthy controls (N=9) and combined these results with two public microarray leukocytes datasets. Through combination of transcriptome and proteome profiling, we identified 170 co-differentially expressed genes/proteins. Among these, 122 genes/proteins displayed the same expression trend. Ingenuity Pathway Analysis revealed pathways related to lymphocyte functions with decreased status, and defense processes that were predicted to be strongly increased. Protein-protein interaction network analyses revealed two densely connected regions, which mainly included down-regulated genes/proteins that were related to the transcription of RNA, translation of proteins, and mitochondrial translation. Additionally, we identified one module comprising of up-regulated genes/proteins, which were mainly related to low-density neutrophils (LDNs). LDNs were reported in sepsis and in COVID-19. Changes in gene expression level were validated using quantitative real-time PCR in PBMCs from patients with sepsis. To further support that the source of the upregulated module of genes/proteins found in our results were derived from LDNs, we identified an increase of this population by flow cytometry in PBMC samples obtained from the same cohort of septic patients included in the proteomic analysis. This study provides new insights into a reprioritization of biological functions in response to sepsis that involved a transcriptional and translational shutdown of genes/proteins, with exception of a set of genes/proteins related to LDNs and host-defense system.


Subject(s)
Leukocytes, Mononuclear/metabolism , Neutrophils/metabolism , Sepsis/metabolism , Databases, Factual , Gene Expression Profiling , Gene Expression Regulation , Humans , Leukocytes, Mononuclear/cytology , Myeloid-Derived Suppressor Cells/cytology , Myeloid-Derived Suppressor Cells/metabolism , Neutrophils/cytology , Protein Interaction Maps , Proteomics , Sepsis/genetics , Sepsis/immunology
6.
Cell Rep ; 37(1): 109793, 2021 10 05.
Article in English | MEDLINE | ID: covidwho-1415261

ABSTRACT

The mortality risk of coronavirus disease 2019 (COVID-19) patients has been linked to the cytokine storm caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Understanding the inflammatory responses shared between COVID-19 and other infectious diseases that feature cytokine storms may therefore help in developing improved therapeutic strategies. Here, we use integrative analysis of single-cell transcriptomes to characterize the inflammatory signatures of peripheral blood mononuclear cells from patients with COVID-19, sepsis, and HIV infection. We identify ten hyperinflammatory cell subtypes in which monocytes are the main contributors to the transcriptional differences in these infections. Monocytes from COVID-19 patients share hyperinflammatory signatures with HIV infection and immunosuppressive signatures with sepsis. Finally, we construct a "three-stage" model of heterogeneity among COVID-19 patients, related to the hyperinflammatory and immunosuppressive signatures in monocytes. Our study thus reveals cellular and molecular insights about inflammatory responses to SARS-CoV-2 infection and provides therapeutic guidance to improve treatments for subsets of COVID-19 patients.


Subject(s)
COVID-19/blood , COVID-19/immunology , HIV Infections/blood , Leukocytes, Mononuclear/metabolism , SARS-CoV-2/immunology , Sepsis/blood , Transcriptome , COVID-19/virology , Cytokine Release Syndrome/blood , Cytokine Release Syndrome/immunology , Cytokines/blood , Data Analysis , Datasets as Topic , HIV Infections/immunology , HIV-1/immunology , Humans , Inflammation/blood , Leukocytes, Mononuclear/immunology , Sepsis/immunology , Single-Cell Analysis
7.
Front Immunol ; 12: 683879, 2021.
Article in English | MEDLINE | ID: covidwho-1369666

ABSTRACT

Diseases caused by pathogenic bacteria in animals (e.g., bacterial pneumonia, meningitis and sepsis) and plants (e.g., bacterial wilt, angular spot and canker) lead to high prevalence and mortality, and decomposition of plant leaves, respectively. Melatonin, an endogenous molecule, is highly pleiotropic, and accumulating evidence supports the notion that melatonin's actions in bacterial infection deserve particular attention. Here, we summarize the antibacterial effects of melatonin in vitro, in animals as well as plants, and discuss the potential mechanisms. Melatonin exerts antibacterial activities not only on classic gram-negative and -positive bacteria, but also on members of other bacterial groups, such as Mycobacterium tuberculosis. Protective actions against bacterial infections can occur at different levels. Direct actions of melatonin may occur only at very high concentrations, which is at the borderline of practical applicability. However, various indirect functions comprise activation of hosts' defense mechanisms or, in sepsis, attenuation of bacterially induced inflammation. In plants, its antibacterial functions involve the mitogen-activated protein kinase (MAPK) pathway; in animals, protection by melatonin against bacterially induced damage is associated with inhibition or activation of various signaling pathways, including key regulators such as NF-κB, STAT-1, Nrf2, NLRP3 inflammasome, MAPK and TLR-2/4. Moreover, melatonin can reduce formation of reactive oxygen and nitrogen species (ROS, RNS), promote detoxification and protect mitochondrial damage. Altogether, we propose that melatonin could be an effective approach against various pathogenic bacterial infections.


Subject(s)
Anti-Bacterial Agents/pharmacology , Inflammasomes/metabolism , Melatonin/pharmacology , Sepsis/metabolism , Signal Transduction/drug effects , Animals , Humans , Inflammasomes/drug effects , Mitogen-Activated Protein Kinases/drug effects , Mitogen-Activated Protein Kinases/metabolism , NF-kappa B/drug effects , NF-kappa B/metabolism , Plant Leaves , Reactive Oxygen Species , Sepsis/genetics , Sepsis/immunology
8.
Int J Med Sci ; 18(14): 3236-3248, 2021.
Article in English | MEDLINE | ID: covidwho-1360866

ABSTRACT

Natural killer cells, one of the important types of innate immune cells, play a pivotal role in the antiviral process in vivo. It has been shown that increasing NK cell activity may promote the alleviation of viral infections, even severe infection-induced sepsis. Given the current state of the novel coronavirus (SARS-CoV-2) global pandemic, clarifying the anti-viral function of NK cells would be helpful for revealing the mechanism of host immune responses and decipher the progression of COVID-19 and providing important clues for combating this pandemic. In this review, we summarize the roles of NK cells in viral infection and sepsis as well as the potential possibilities of NK cell-based immunotherapy for treating COVID-19.


Subject(s)
COVID-19/immunology , Host-Pathogen Interactions/immunology , Killer Cells, Natural/physiology , Sepsis/immunology , COVID-19/therapy , Humans , Immunotherapy , SARS-CoV-2 , Sepsis/virology
10.
Exp Mol Med ; 53(7): 1116-1123, 2021 07.
Article in English | MEDLINE | ID: covidwho-1307318

ABSTRACT

Interleukin-6 (IL-6) plays a crucial role in host defense against infection and tissue injuries and is a bioindicator of multiple distinct types of cytokine storms. In this review, we present the current understanding of the diverse roles of IL-6, its receptors, and its signaling during acute severe systemic inflammation. IL-6 directly affects vascular endothelial cells, which produce several types of cytokines and chemokines and activate the coagulation cascade. Endothelial cell dysregulation, characterized by abnormal coagulation and vascular leakage, is a common complication in cytokine storms. Emerging evidence indicates that a humanized anti-IL-6 receptor antibody, tocilizumab, can effectively block IL-6 signaling and has beneficial effects in rheumatoid arthritis, juvenile systemic idiopathic arthritis, and Castleman's disease. Recent work has also demonstrated the beneficial effect of tocilizumab in chimeric antigen receptor T-cell therapy-induced cytokine storms as well as coronavirus disease 2019 (COVID-19). Here, we highlight the distinct contributions of IL-6 signaling to the pathogenesis of several types of cytokine storms and discuss potential therapeutic strategies for the management of cytokine storms, including those associated with sepsis and COVID-19.


Subject(s)
Antibodies, Monoclonal, Humanized/therapeutic use , COVID-19/prevention & control , Interleukin-6/genetics , Receptors, Interleukin-6/genetics , Antibodies, Monoclonal, Humanized/immunology , COVID-19/genetics , COVID-19/immunology , COVID-19/pathology , Cytokine Release Syndrome/genetics , Cytokine Release Syndrome/immunology , Cytokines/genetics , Cytokines/metabolism , Endothelium, Vascular/immunology , Humans , Interleukin-6/antagonists & inhibitors , Interleukin-6/immunology , Receptors, Interleukin-6/antagonists & inhibitors , Receptors, Interleukin-6/immunology , SARS-CoV-2/immunology , SARS-CoV-2/pathogenicity , Sepsis/genetics , Sepsis/immunology , Sepsis/pathology , Sepsis/prevention & control
11.
Am J Physiol Lung Cell Mol Physiol ; 321(2): L485-L489, 2021 08 01.
Article in English | MEDLINE | ID: covidwho-1299247

ABSTRACT

COVID-19, the disease caused by the SARS-CoV-2 virus, can progress to multisystem organ failure and viral sepsis characterized by respiratory failure, arrhythmias, thromboembolic complications, and shock with high mortality. Autopsy and preclinical evidence implicate aberrant complement activation in endothelial injury and organ failure. Erythrocytes express complement receptors and are capable of binding immune complexes; therefore, we investigated complement activation in patients with COVID-19 using erythrocytes as a tool to diagnose complement activation. We discovered enhanced C3b and C4d deposition on erythrocytes in COVID-19 sepsis patients and non-COVID sepsis patients compared with healthy controls, supporting the role of complement in sepsis-associated organ injury. Our data suggest that erythrocytes may contribute to a precision medicine approach to sepsis and have diagnostic value in monitoring complement dysregulation in COVID-19-sepsis and non-COVID sepsis and identifying patients who may benefit from complement targeted therapies.


Subject(s)
COVID-19/complications , Complement Activation/immunology , Complement C3b/immunology , Complement C4b/immunology , Erythrocytes/immunology , Peptide Fragments/immunology , Respiratory Insufficiency/diagnosis , Sepsis/diagnosis , COVID-19/immunology , COVID-19/virology , Complement C3b/metabolism , Complement C4b/metabolism , Erythrocytes/metabolism , Erythrocytes/virology , Female , Humans , Male , Middle Aged , Peptide Fragments/metabolism , Respiratory Insufficiency/immunology , Respiratory Insufficiency/metabolism , Respiratory Insufficiency/virology , SARS-CoV-2/isolation & purification , Sepsis/immunology , Sepsis/metabolism , Sepsis/virology
12.
Crit Care ; 25(1): 236, 2021 07 06.
Article in English | MEDLINE | ID: covidwho-1298056

ABSTRACT

Infectious diseases may affect brain function and cause encephalopathy even when the pathogen does not directly infect the central nervous system, known as infectious disease-associated encephalopathy. The systemic inflammatory process may result in neuroinflammation, with glial cell activation and increased levels of cytokines, reduced neurotrophic factors, blood-brain barrier dysfunction, neurotransmitter metabolism imbalances, and neurotoxicity, and behavioral and cognitive impairments often occur in the late course. Even though infectious disease-associated encephalopathies may cause devastating neurologic and cognitive deficits, the concept of infectious disease-associated encephalopathies is still under-investigated; knowledge of the underlying mechanisms, which may be distinct from those of encephalopathies of non-infectious cause, is still limited. In this review, we focus on the pathophysiology of encephalopathies associated with peripheral (sepsis, malaria, influenza, and COVID-19), emerging therapeutic strategies, and the role of neuroinflammation.


Subject(s)
Brain Diseases/immunology , COVID-19/complications , Cytokines/immunology , Influenza, Human/complications , Malaria/complications , Sepsis/complications , Blood-Brain Barrier/immunology , Brain Diseases/prevention & control , COVID-19/immunology , Humans , Influenza, Human/immunology , Malaria/immunology , Sepsis/immunology
13.
Hum Immunol ; 82(10): 733-745, 2021 Oct.
Article in English | MEDLINE | ID: covidwho-1293817

ABSTRACT

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing COVID-19 is associated with excessive inflammation, as a main reason for severe condition and death. Increased inflammatory cytokines and humoral response to SARS-CoV-2 correlate with COVID-19 immunity and pathogenesis. Importantly, the levels of pro-inflammatory cytokines that increase profoundly in systemic circulation appear as part of the clinical pictures of two overlapping conditions, sepsis and the hemophagocytic syndromes. Both conditions can develop lethal inflammatory responses that lead to tissue damage, however, in many patients hemophagocytic lymphohistiocytosis (HLH) can be differentiated from sepsis. This is a key issue because the life-saving aggressive immunosuppressive treatment, required in the HLH therapy, is absent in sepsis guidelines. This paper aims to describe the pathophysiology and clinical relevance of these distinct entities in the course of COVID-19 that resemble sepsis and further highlights two effector arms of the humoral immune response (inflammatory cytokine and immunoglobulin production) during COVID-19 infection.


Subject(s)
COVID-19/immunology , Immunity, Humoral/immunology , Animals , Cytokines/immunology , Humans , Inflammation/immunology , Lymphohistiocytosis, Hemophagocytic/immunology , SARS-CoV-2/immunology , Sepsis/immunology
14.
Crit Care Med ; 49(10): 1717-1725, 2021 10 01.
Article in English | MEDLINE | ID: covidwho-1232230

ABSTRACT

OBJECTIVES: Although clinical presentation of coronavirus disease 2019 has been extensively described, immune response to severe acute respiratory syndrome coronavirus 2 remains yet not fully understood. Similarities with bacterial sepsis were observed; however, few studies specifically addressed differences of immune response between both conditions. Here, we report a longitudinal analysis of the immune response in coronavirus disease 2019 patients, its correlation with outcome, and comparison between severe coronavirus disease 2019 patients and septic patients. DESIGN: Longitudinal, retrospective observational study. SETTING: Tertiary-care hospital during the first 2020 coronavirus disease 2019 outbreak in France. PATIENTS: All successive patients with confirmed severe acute respiratory syndrome coronavirus 2 infection admitted to the emergency department, medical ward, and ICU with at least one available immunophenotyping performed during hospital stay. MEASUREMENTS AND MAIN RESULTS: Between March and April 2020, 247 patients with coronavirus disease 2019 were included and compared with a historical cohort of 108 severe septic patients. Nonsevere coronavirus disease 2019 patients (n = 153) presented normal or slightly altered immune profiles. Severe coronavirus disease 2019 (n = 94) immune profile differed from sepsis. Coronavirus disease 2019 exhibited profound and prolonged lymphopenia (mostly on CD3, CD4, CD8, and NK cells), neutrophilia, and human leukocyte antigen D receptor expression on CD14+ monocytes down-regulation. Surprisingly, coronavirus disease 2019 patients presented a unique profile of B cells expansion, basophilia, and eosinophilia. Lymphopenia, human leukocyte antigen D receptor expression on CD14+ monocytes down-regulation, and neutrophilia were associated with a worsened outcome, whereas basophilia and eosinophilia were associated with survival. Circulating immune cell kinetics differed between severe coronavirus disease 2019 and sepsis, lack of correction of immune alterations in coronavirus disease 2019 patients during the first 2 weeks of ICU admission was associated with death and nosocomial infections. CONCLUSIONS: Circulating immune cells profile differs between mild and severe coronavirus disease 2019 patients. Severe coronavirus disease 2019 is associated with a unique immune profile as compared with sepsis. Several immune features are associated with outcome. Thus, immune monitoring of coronavirus disease 2019 might be of help for patient management.


Subject(s)
COVID-19/complications , Immunologic Factors/analysis , Kinetics , Sepsis/complications , Aged , COVID-19/epidemiology , COVID-19/immunology , Female , France/epidemiology , Humans , Intensive Care Units/organization & administration , Intensive Care Units/statistics & numerical data , Longitudinal Studies , Male , Middle Aged , Retrospective Studies , Sepsis/epidemiology , Sepsis/immunology
15.
Proc Natl Acad Sci U S A ; 118(10)2021 03 09.
Article in English | MEDLINE | ID: covidwho-1116057

ABSTRACT

Blood pH is tightly maintained between 7.35 and 7.45, and acidosis (pH <7.3) indicates poor prognosis in sepsis, wherein lactic acid from anoxic tissues overwhelms the buffering capacity of blood. Poor sepsis prognosis is also associated with low zinc levels and the release of High mobility group box 1 (HMGB1) from activated and/or necrotic cells. HMGB1 added to whole blood at physiological pH did not bind leukocyte receptors, but lowering pH with lactic acid to mimic sepsis conditions allowed binding, implying the presence of natural inhibitor(s) preventing binding at normal pH. Testing micromolar concentrations of divalent cations showed that zinc supported the robust binding of sialylated glycoproteins with HMGB1. Further characterizing HMGB1 as a sialic acid-binding lectin, we found that optimal binding takes place at normal blood pH and is markedly reduced when pH is adjusted with lactic acid to levels found in sepsis. Glycan array studies confirmed the binding of HMGB1 to sialylated glycan sequences typically found on plasma glycoproteins, with binding again being dependent on zinc and normal blood pH. Thus, HMGB1-mediated hyperactivation of innate immunity in sepsis requires acidosis, and micromolar zinc concentrations are protective. We suggest that the potent inflammatory effects of HMGB1 are kept in check via sequestration by plasma sialoglycoproteins at physiological pH and triggered when pH and zinc levels fall in late stages of sepsis. Current clinical trials independently studying zinc supplementation, HMGB1 inhibition, or pH normalization may be more successful if these approaches are combined and perhaps supplemented by infusions of heavily sialylated molecules.


Subject(s)
Acidosis/blood , HMGB1 Protein/blood , Sepsis/blood , Sialoglycoproteins/blood , Zinc/blood , Acidosis/immunology , Acidosis/metabolism , Acidosis/pathology , Carrier Proteins , HMGB1 Protein/pharmacology , Humans , Hydrogen-Ion Concentration , Immunity, Innate , Lipopolysaccharides/pharmacology , Polysaccharides/chemistry , Sepsis/immunology , Sepsis/pathology , Sialic Acids/chemistry , Sialoglycoproteins/chemistry , Zinc/metabolism
16.
J Clin Endocrinol Metab ; 106(7): 1994-2009, 2021 06 16.
Article in English | MEDLINE | ID: covidwho-1133638

ABSTRACT

CONTEXT: Lymphopenia is a key feature of immune dysfunction in patients with bacterial sepsis and coronavirus disease 2019 (COVID-19) and is associated with poor clinical outcomes, but the cause is largely unknown. Severely ill patients may present with thyroid function abnormalities, so-called nonthyroidal illness syndrome, and several studies have linked thyrotropin (thyroid stimulating hormone, TSH) and the thyroid hormones thyroxine (T4) and 3,5,3'-triiodothyronine (T3) to homeostatic regulation and function of lymphocyte populations. OBJECTIVE: This work aimed to test the hypothesis that abnormal thyroid function correlates with lymphopenia in patients with severe infections. METHODS: A retrospective analysis of absolute lymphocyte counts, circulating TSH, T4, free T4 (FT4), T3, albumin, and inflammatory biomarkers was performed in 2 independent hospitalized study populations: bacterial sepsis (n = 224) and COVID-19 patients (n = 161). A subgroup analysis was performed in patients with severe lymphopenia and normal lymphocyte counts. RESULTS: Only T3 significantly correlated (ρ = 0.252) with lymphocyte counts in patients with bacterial sepsis, and lower concentrations were found in severe lymphopenic compared to nonlymphopenic patients (n = 56 per group). Severe lymphopenic COVID-19 patients (n = 17) showed significantly lower plasma concentrations of TSH, T4, FT4, and T3 compared to patients without lymphopenia (n = 18), and demonstrated significantly increased values of the inflammatory markers interleukin-6, C-reactive protein, and ferritin. Remarkably, after 1 week of follow-up, the majority (12 of 15) of COVID-19 patients showed quantitative recovery of their lymphocyte numbers, whereas TSH and thyroid hormones remained mainly disturbed. CONCLUSION: Abnormal thyroid function correlates with lymphopenia in patients with severe infections, like bacterial sepsis and COVID-19, but future studies need to establish whether a causal relationship is involved.


Subject(s)
COVID-19/complications , Euthyroid Sick Syndromes/diagnosis , Lymphopenia/immunology , Sepsis/complications , Aged , Aged, 80 and over , COVID-19/blood , COVID-19/immunology , Euthyroid Sick Syndromes/blood , Euthyroid Sick Syndromes/immunology , Female , Greece , Humans , Lymphocyte Count , Lymphopenia/blood , Lymphopenia/diagnosis , Male , Netherlands , Retrospective Studies , SARS-CoV-2/immunology , Sepsis/blood , Sepsis/immunology , Thyroid Hormones/blood , Thyroid Hormones/immunology , Thyrotropin/blood , Thyrotropin/immunology
17.
Genomics ; 113(3): 1219-1233, 2021 05.
Article in English | MEDLINE | ID: covidwho-1118728

ABSTRACT

Sepsis is a leading cause of mortality in intensive care unit worldwide, it's accompanied by immune cell dysfunction induced by multiple factors. However, little is known about the specific alterations in immune cells in the dynamic pathogenesis of sepsis secondary to bacterial pneumonia. Here, we used single cell RNA sequencing (scRNA-seq) to profile peripheral blood mononuclear cells (PBMCs) in a healthy control and two patients with sepsis secondary to bacterial pneumonia, including acute, stable and recovery stage. We analyzed the quantity and function of immune cells. During disease course, interferon gamma response was upregulated; T/NK cell subtypes presented activation and exhaustion properties, which might be driven by monocytes through IL-1ß signaling pathways; The proportion of plasma cells was increased, which might be driven by NK cells through IFN signaling pathways; Additionally, interferon gamma response was upregulated to a greater degree in sepsis secondary to pneumonia induced by SARS-COV-2 compared with that induced by influenza virus and bacteria.


Subject(s)
Pneumonia, Bacterial , Sepsis , Sequence Analysis, RNA/methods , Single-Cell Analysis/methods , Aged , COVID-19/complications , COVID-19/genetics , COVID-19/immunology , Case-Control Studies , Cells, Cultured , Female , Humans , Influenza, Human/complications , Influenza, Human/genetics , Influenza, Human/immunology , Leukocytes/immunology , Leukocytes/metabolism , Leukocytes, Mononuclear/immunology , Leukocytes, Mononuclear/metabolism , Male , Middle Aged , Monocytes/immunology , Monocytes/metabolism , Pneumonia, Bacterial/complications , Pneumonia, Bacterial/genetics , Pneumonia, Bacterial/immunology , RNA-Seq , SARS-CoV-2/immunology , Sepsis/genetics , Sepsis/immunology , Sepsis/microbiology , Sepsis/virology
18.
Int J Mol Sci ; 22(4)2021 Feb 20.
Article in English | MEDLINE | ID: covidwho-1090323

ABSTRACT

Severe COVID-19 is characterized by a "cytokine storm", the mechanism of which is not yet understood. I propose that cytokine storms result from synergistic interactions among Toll-like receptors (TLR) and nucleotide-binding oligomerization domain-like receptors (NLR) due to combined infections of SARS-CoV-2 with other microbes, mainly bacterial and fungal. This proposition is based on eight linked types of evidence and their logical connections. (1) Severe cases of COVID-19 differ from healthy controls and mild COVID-19 patients in exhibiting increased TLR4, TLR7, TLR9 and NLRP3 activity. (2) SARS-CoV-2 and related coronaviruses activate TLR3, TLR7, RIG1 and NLRP3. (3) SARS-CoV-2 cannot, therefore, account for the innate receptor activation pattern (IRAP) found in severe COVID-19 patients. (4) Severe COVID-19 also differs from its mild form in being characterized by bacterial and fungal infections. (5) Respiratory bacterial and fungal infections activate TLR2, TLR4, TLR9 and NLRP3. (6) A combination of SARS-CoV-2 with bacterial/fungal coinfections accounts for the IRAP found in severe COVID-19 and why it differs from mild cases. (7) Notably, TLR7 (viral) and TLR4 (bacterial/fungal) synergize, TLR9 and TLR4 (both bacterial/fungal) synergize and TLR2 and TLR4 (both bacterial/fungal) synergize with NLRP3 (viral and bacterial). (8) Thus, a SARS-CoV-2-bacterium/fungus coinfection produces synergistic innate activation, resulting in the hyperinflammation characteristic of a cytokine storm. Unique clinical, experimental and therapeutic predictions (such as why melatonin is effective in treating COVID-19) are discussed, and broader implications are outlined for understanding why other syndromes such as acute lung injury, acute respiratory distress syndrome and sepsis display varied cytokine storm symptoms.


Subject(s)
Acute Lung Injury/immunology , COVID-19/immunology , Cytokine Release Syndrome/immunology , NLR Proteins/immunology , Respiratory Distress Syndrome/immunology , Sepsis/immunology , Toll-Like Receptors/immunology , Acute Lung Injury/drug therapy , Acute Lung Injury/metabolism , Animals , COVID-19/drug therapy , Cytokine Release Syndrome/drug therapy , Cytokine Release Syndrome/metabolism , Humans , Inflammation/drug therapy , Inflammation/immunology , Respiratory Distress Syndrome/drug therapy , Respiratory Distress Syndrome/metabolism , SARS-CoV-2/immunology , Sepsis/drug therapy , Sepsis/metabolism , Toll-Like Receptors/metabolism
19.
Med Hypotheses ; 149: 110537, 2021 Apr.
Article in English | MEDLINE | ID: covidwho-1085501

ABSTRACT

As the COVID-19 pandemic continues, researchers seek to identify efficacious treatments. Current approaches to COVID-19 therapeutics focus on antiviral agents, convalescent plasma, monoclonal antibodies, immunomodulators and more traditional therapies such as steroids [1-6]. Reversing disturbances in coagulation has also been identified as a priority area for candidate therapies, such as through the Accelerating COVID-19 Therapeutic Interventions and Vaccines 4 adaptive clinical trial (ACTIV-4) which is currently evaluating aspirin, heparins and apixaban [7]. Since there is a clear relationship between mechanisms of coagulation and the immune response, it is possible that reversing disturbances in coagulation may diminish the dysregulated immune response observed in COVID-19. The basis for this hypothesis is described below and is followed by discussion of a proposed candidate therapy - activated protein C. By treating COVID-19 patients using a novel approach, which does not focus on immune-based or antiviral treatments, but instead which addresses both the anti-thrombotic and inflammatory consequences of infection, the hope is that new therapeutic targets can be considered and new candidate therapies, such as activated protein C, may be evaluated.


Subject(s)
COVID-19/drug therapy , Fibrinolytic Agents/therapeutic use , Protein C/therapeutic use , Animals , Antiviral Agents/therapeutic use , Blood Coagulation/drug effects , Humans , Inflammation/drug therapy , Models, Theoretical , Recombinant Proteins/therapeutic use , Sepsis/immunology , Sepsis/therapy
20.
Int J Mol Sci ; 21(15)2020 Aug 03.
Article in English | MEDLINE | ID: covidwho-1006953

ABSTRACT

Sepsis is a life-threatening organ dysfunction, defined by a dysregulated host immune response to infection. During sepsis, the finely tuned system of immunity, inflammation and anti-inflammation is disturbed in a variety of ways. Both pro-inflammatory and anti-inflammatory pathways are upregulated, activation of the coagulation cascade and complement and sepsis-induced lymphopenia occur. Due to the manifold interactions in this network, the use of IgM-enriched intravenous immunoglobulins seems to be a promising therapeutic approach. Unfortunately, there is still a lack of evidence-based data to answer the important questions of appropriate patient populations, optimal timing and dosage of intravenous immunoglobulins. With this review, we aim to provide an overview of the role of immunoglobulins, with emphasis on IgM-enriched formulations, in the therapy of adult patients with sepsis and septic shock.


Subject(s)
Immunoglobulin M/therapeutic use , Immunoglobulins, Intravenous/therapeutic use , Inflammation/therapy , Sepsis/therapy , Humans , Immunoglobulin M/immunology , Immunologic Factors/immunology , Immunologic Factors/therapeutic use , Inflammation/blood , Inflammation/immunology , Sepsis/blood , Sepsis/immunology , Shock, Septic/immunology
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