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1.
Viruses ; 13(12)2021 12 14.
Article in English | MEDLINE | ID: covidwho-1572670

ABSTRACT

SARS-CoV-2 is a new type of coronavirus that has caused worldwide pandemic. The disease induced by SARS-CoV-2 is called COVID-19. A majority of people with COVID-19 have relatively mild respiratory symptoms. However, a small percentage of COVID-19 patients develop a severe disease where multiple organs are affected. These severe forms of SARS-CoV-2 infections are associated with excessive production of pro-inflammatory cytokines, so called "cytokine storm". Inflammasomes, which are protein complexes of the innate immune system orchestrate development of local and systemic inflammation during virus infection. Recent data suggest involvement of inflammasomes in severe COVID-19. Activation of inflammasome exerts two major effects: it activates caspase-1-mediated processing and secretion of pro-inflammatory cytokines IL-1ß and IL-18, and induces inflammatory cell death, pyroptosis, via protein called gasdermin D. Here, we provide comprehensive review of current understanding of the activation and possible functions of different inflammasome structures during SARS-CoV-2 infection and compare that to response caused by influenza A virus. We also discuss how novel SARS-CoV-2 mRNA vaccines activate innate immune response, which is a prerequisite for the activation of protective adaptive immune response.


Subject(s)
COVID-19/immunology , Inflammasomes/immunology , Adaptive Immunity , COVID-19 Vaccines , Cell Death , Cytokine Release Syndrome , Cytokines/immunology , Humans , Immunity, Innate , Inflammation , Interleukin-18 , Interleukin-1beta , Neoplasm Proteins , Pyroptosis , SARS-CoV-2/immunology
2.
Molecules ; 26(24)2021 Dec 09.
Article in English | MEDLINE | ID: covidwho-1572567

ABSTRACT

COVID-19 is the name of the disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection that occurred in 2019. The virus-host-specific interactions, molecular targets on host cell deaths, and the involved signaling are crucial issues, which become potential targets for treatment. Spike protein, angiotensin-converting enzyme 2 (ACE2), cathepsin L-cysteine peptidase, transmembrane protease serine 2 (TMPRSS2), nonstructural protein 1 (Nsp1), open reading frame 7a (ORF7a), viral main protease (3C-like protease (3CLpro) or Mpro), RNA dependent RNA polymerase (RdRp) (Nsp12), non-structural protein 13 (Nsp13) helicase, and papain-like proteinase (PLpro) are molecules associated with SARS-CoV infection and propagation. SARS-CoV-2 can induce host cell death via five kinds of regulated cell death, i.e., apoptosis, necroptosis, pyroptosis, autophagy, and PANoptosis. The mechanisms of these cell deaths are well established and can be disrupted by synthetic small molecules or natural products. There are a variety of compounds proven to play roles in the cell death inhibition, such as pan-caspase inhibitor (z-VAD-fmk) for apoptosis, necrostatin-1 for necroptosis, MCC950, a potent and specific inhibitor of the NLRP3 inflammasome in pyroptosis, and chloroquine/hydroxychloroquine, which can mitigate the corresponding cell death pathways. However, NF-κB signaling is another critical anti-apoptotic or survival route mediated by SARS-CoV-2. Such signaling promotes viral survival, proliferation, and inflammation by inducing the expression of apoptosis inhibitors such as Bcl-2 and XIAP, as well as cytokines, e.g., TNF. As a result, tiny natural compounds functioning as proteasome inhibitors such as celastrol and curcumin can be used to modify NF-κB signaling, providing a responsible method for treating SARS-CoV-2-infected patients. The natural constituents that aid in inhibiting viral infection, progression, and amplification of coronaviruses are also emphasized, which are in the groups of alkaloids, flavonoids, terpenoids, diarylheptanoids, and anthraquinones. Natural constituents derived from medicinal herbs have anti-inflammatory and antiviral properties, as well as inhibitory effects, on the viral life cycle, including viral entry, replication, assembly, and release of COVID-19 virions. The phytochemicals contain a high potential for COVID-19 treatment. As a result, SARS-CoV-2-infected cell death processes and signaling might be of high efficacy for therapeutic targeting effects and yielding encouraging outcomes.


Subject(s)
COVID-19/drug therapy , Cell Death/drug effects , Drug Discovery/methods , Molecular Targeted Therapy/methods , SARS-CoV-2/drug effects , Amino Acid Chloromethyl Ketones/pharmacology , Antiviral Agents/pharmacology , Apoptosis/drug effects , Furans/pharmacology , Humans , Hydroxychloroquine/pharmacology , Imidazoles/pharmacology , Indenes/pharmacology , Indoles/pharmacology , Necroptosis/drug effects , Phytochemicals/pharmacology , Pyroptosis/drug effects , SARS-CoV-2/metabolism , Signal Transduction/drug effects , Sulfonamides/pharmacology , Viral Proteins/antagonists & inhibitors
3.
Viruses ; 13(10)2021 10 15.
Article in English | MEDLINE | ID: covidwho-1470996

ABSTRACT

Infections with viral pathogens are widespread and can cause a variety of different diseases. In-depth knowledge about viral triggers initiating an immune response is necessary to decipher viral pathogenesis. Inflammasomes, as part of the innate immune system, can be activated by viral pathogens. However, viral structural components responsible for inflammasome activation remain largely unknown. Here we analyzed glycoproteins derived from SARS-CoV-1/2, HCMV and HCV, required for viral entry and fusion, as potential triggers of NLRP3 inflammasome activation and pyroptosis in THP-1 macrophages. All tested glycoproteins were able to potently induce NLRP3 inflammasome activation, indicated by ASC-SPECK formation and secretion of cleaved IL-1ß. Lytic cell death via gasdermin D (GSDMD), pore formation, and pyroptosis are required for IL-1ß release. As a hallmark of pyroptosis, we were able to detect cleavage of GSDMD and, correspondingly, cell death in THP-1 macrophages. CRISPR-Cas9 knockout of NLRP3 and GSDMD in THP-1 macrophages confirmed and strongly support the evidence that viral glycoproteins can act as innate immunity triggers. With our study, we decipher key mechanisms of viral pathogenesis by showing that viral glycoproteins potently induce innate immune responses. These insights could be beneficial in vaccine development and provide new impulses for the investigation of vaccine-induced innate immunity.


Subject(s)
Immunity, Innate/immunology , Inflammasomes/immunology , Macrophages/immunology , NLR Family, Pyrin Domain-Containing 3 Protein/immunology , Viral Envelope Proteins/immunology , Viral Fusion Proteins/immunology , Cell Line, Tumor , Cytomegalovirus/immunology , Hepacivirus/immunology , Humans , Interleukin-1beta/biosynthesis , Interleukin-1beta/immunology , Pyroptosis/immunology , SARS Virus/immunology , SARS-CoV-2/immunology , THP-1 Cells
4.
Front Immunol ; 12: 728896, 2021.
Article in English | MEDLINE | ID: covidwho-1456291

ABSTRACT

A purified spike (S) glycoprotein of severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) coronavirus was used to study its effects on THP-1 macrophages, peripheral blood mononuclear cells (PBMCs), and HUVEC cells. The S protein mediates the entry of SARS-CoV-2 into cells through binding to the angiotensin-converting enzyme 2 (ACE2) receptors. We measured the viability, intracellular cytokine release, oxidative stress, proinflammatory markers, and THP-1-like macrophage polarization. We observed an increase in apoptosis, ROS generation, MCP-1, and intracellular calcium expression in the THP-1 macrophages. Stimulation with the S protein polarizes the THP-1 macrophages towards proinflammatory futures with an increase in the TNFα and MHC-II M1-like phenotype markers. Treating the cells with an ACE inhibitor, perindopril, at 100 µM reduced apoptosis, ROS, and MHC-II expression induced by S protein. We analyzed the sensitivity of the HUVEC cells after the exposure to a conditioned media (CM) of THP-1 macrophages stimulated with the S protein. The CM induced endothelial cell apoptosis and MCP-1 expression. Treatment with perindopril reduced these effects. However, the direct stimulation of the HUVEC cells with the S protein, slightly increased HIF1α and MCP-1 expression, which was significantly increased by the ACE inhibitor treatment. The S protein stimulation induced ROS generation and changed the mitogenic responses of the PBMCs through the upregulation of TNFα and interleukin (IL)-17 cytokine expression. These effects were reduced by the perindopril (100 µM) treatment. Proteomic analysis of the S protein stimulated THP-1 macrophages with or without perindopril (100 µM) exposed more than 400 differentially regulated proteins. Our results provide a mechanistic analysis suggesting that the blood and vascular components could be activated directly through S protein systemically present in the circulation and that the activation of the local renin angiotensin system may be partially involved in this process. Graphical: Suggested pathways that might be involved at least in part in S protein inducing activation of inflammatory markers (red narrow) and angiotensin-converting enzyme inhibitor (ACEi) modulation of this process (green narrow).


Subject(s)
Angiotensin-Converting Enzyme Inhibitors/pharmacology , Apoptosis/drug effects , COVID-19/immunology , Macrophages/immunology , Oxidative Stress/drug effects , Perindopril/pharmacology , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , COVID-19/drug therapy , COVID-19/physiopathology , COVID-19/virology , Cell Line , Humans , Macrophages/drug effects , Peptidyl-Dipeptidase A/genetics , Peptidyl-Dipeptidase A/immunology , Pyroptosis/drug effects , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics
5.
Acta Pharmacol Sin ; 42(11): 1913-1920, 2021 11.
Article in English | MEDLINE | ID: covidwho-1437673

ABSTRACT

Sepsis is a dysregulated immune response to infection and potentially leads to life-threatening organ dysfunction, which is often seen in serious Covid-19 patients. Disulfiram (DSF), an old drug that has been used to treat alcohol addiction for decades, has recently been identified as a potent inhibitor of the gasdermin D (GSDMD)-induced pore formation that causes pyroptosis and inflammatory cytokine release. Therefore, DSF represents a promising therapeutic for the treatment of inflammatory disorders. Lactoferrin (LF) is a multifunctional glycoprotein with potent antibacterial and anti-inflammatory activities that acts by neutralizing circulating endotoxins and activating cellular responses. In addition, LF has been well exploited as a drug nanocarrier and targeting ligands. In this study, we developed a DSF-LF nanoparticulate system (DSF-LF NP) for combining the immunosuppressive activities of both DSF and LF. DSF-LF NPs could effectively block pyroptosis and inflammatory cytokine release from macrophages. Treatment with DSF-LF NPs showed remarkable therapeutic effects on lipopolysaccharide (LPS)-induced sepsis. In addition, this therapeutic strategy was also applied to treat ulcerative colitis (UC), and substantial treatment efficacy was achieved in a murine colitis model. The underlying mode of action of these DSF-LF-NPs may contribute to efficiently suppressing macrophage-mediated inflammatory responses and ameliorating the complications caused by sepsis and UC. As macrophage pyroptosis plays a pivotal role in inflammation, this safe and effective biomimetic nanomedicine may offer a versatile therapeutic strategy for treating various inflammatory diseases by repurposing DSF.


Subject(s)
COVID-19 , Colitis, Ulcerative , Disulfiram/pharmacokinetics , Lactoferrin , Systemic Inflammatory Response Syndrome , Acetaldehyde Dehydrogenase Inhibitors/pharmacology , Animals , Anti-Inflammatory Agents/pharmacology , Biomimetic Materials/pharmacology , COVID-19/drug therapy , COVID-19/immunology , Colitis, Ulcerative/drug therapy , Colitis, Ulcerative/immunology , Disease Models, Animal , Disulfiram/pharmacology , Drug Carriers/pharmacology , Humans , Immunosuppressive Agents/pharmacology , Lactoferrin/metabolism , Lactoferrin/pharmacology , Lipopolysaccharides/immunology , Macrophages/drug effects , Macrophages/immunology , Mice , Mice, Inbred C57BL , Nanoparticles/therapeutic use , Pyroptosis/drug effects , SARS-CoV-2 , Systemic Inflammatory Response Syndrome/drug therapy , Systemic Inflammatory Response Syndrome/immunology , Systemic Inflammatory Response Syndrome/metabolism , Treatment Outcome
6.
JCI Insight ; 6(17)2021 09 08.
Article in English | MEDLINE | ID: covidwho-1413722

ABSTRACT

Neutrophil-mediated activation and injury of the endothelium play roles in the pathogenesis of diverse disease states ranging from autoimmunity to cancer to COVID-19. Neutralization of cationic proteins (such as neutrophil extracellular trap-derived [NET-derived] histones) with polyanionic compounds has been suggested as a potential strategy for protecting the endothelium from such insults. Here, we report that the US Food and Drug Administration-approved polyanionic agent defibrotide (a pleiotropic mixture of oligonucleotides) directly engages histones and thereby blocks their pathological effects on endothelium. In vitro, defibrotide counteracted endothelial cell activation and pyroptosis-mediated cell death, whether triggered by purified NETs or recombinant histone H4. In vivo, defibrotide stabilized the endothelium and protected against histone-accelerated inferior vena cava thrombosis in mice. Mechanistically, defibrotide demonstrated direct and tight binding to histone H4 as detected by both electrophoretic mobility shift assay and surface plasmon resonance. Taken together, these data provide insights into the potential role of polyanionic compounds in protecting the endothelium from thromboinflammation with potential implications for myriad NET- and histone-accelerated disease states.


Subject(s)
Fibrinolytic Agents/pharmacology , Human Umbilical Vein Endothelial Cells/drug effects , Polydeoxyribonucleotides/pharmacology , Thrombosis/drug therapy , Animals , Extracellular Traps/drug effects , Extracellular Traps/metabolism , Fibrinolytic Agents/therapeutic use , Histones/metabolism , Human Umbilical Vein Endothelial Cells/metabolism , Humans , Male , Mice , Mice, Inbred C57BL , Polydeoxyribonucleotides/therapeutic use , Pyroptosis
7.
Trends Endocrinol Metab ; 32(11): 875-889, 2021 11.
Article in English | MEDLINE | ID: covidwho-1401891

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a pandemic of respiratory and cardiovascular diseases, known as coronavirus disease 2019 (COVID-19). SARS-CoV-2 encodes the structural proteins spike (S), envelope (E), membrane (M), and nucleocapsid (N). The receptor-binding domain on the surface subunit S1 is responsible for attachment of the virus to angiotensin (Ang)-converting enzyme 2 (ACE2), which is highly expressed in host cells. The cytokine storm observed in patients with COVID-19 contributes to the endothelial vascular dysfunction, which can lead to acute respiratory distress syndrome, multiorgan failure, alteration in iron homeostasis, and death. Growth and differentiation factor 15 (GDF15), which belongs to the transforming growth factor-ß (TGF-ß) superfamily of proteins, has a pivotal role in the development and progression of diseases because of its role as a metabolic regulator. In COVID-19, GDF15 activity increases in response to tissue damage. GDF15 appears to be a strong predictor of poor outcomes in patients critically ill with COVID-19 and acts as an 'inflammation-induced central mediator of tissue tolerance' via its metabolic properties. In this review, we examine the potential properties of GDF15 as an emerging modulator of immunity in COVID-19 in association with iron metabolism. The virus life cycle in host cell provides potential targets for drug therapy.


Subject(s)
COVID-19/immunology , Cytokine Release Syndrome/immunology , Endothelium, Vascular/immunology , Growth Differentiation Factor 15/immunology , Iron/metabolism , Apoptosis/immunology , COVID-19/drug therapy , COVID-19/metabolism , Cytokine Release Syndrome/metabolism , Endothelium, Vascular/metabolism , Endothelium, Vascular/physiopathology , Glial Cell Line-Derived Neurotrophic Factor Receptors/immunology , Glial Cell Line-Derived Neurotrophic Factor Receptors/metabolism , Growth Differentiation Factor 15/metabolism , Humans , Immunologic Factors/therapeutic use , Oxidative Stress/immunology , Prognosis , Pyroptosis/immunology , SARS-CoV-2
10.
Front Immunol ; 12: 700152, 2021.
Article in English | MEDLINE | ID: covidwho-1359189

ABSTRACT

Background: Mucosal-associated invariant T (MAIT) cells are considered to participate of the host immune response against acute severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection; however, single-cell transcriptomic profiling of MAIT cells in patients with COVID-19 remains unexplored. Methods: We performed single-cell RNA sequencing analyses on peripheral MAIT cells from 13 patients with COVID-19 and 5 healthy donors. The transcriptional profiles of MAIT cells, together with assembled T-cell receptor sequences, were analyzed. Flow cytometry analysis was also performed to investigate the properties of MAIT cells. Results: We identified that differentially expressed genes (DEGs) of MAIT cells were involved in myeloid leukocyte activation and lymphocyte activation in patients with COVID-19. In addition, in MAIT cells from severe cases, more DEGs were enriched in adaptive cellular and humoral immune responses compared with those in moderate cases. Further analysis indicated that the increase of cell cytotoxicity (killing), chemotaxis, and apoptosis levels in MAIT cells were consistent with disease severity and displayed the highest levels in patients with severe disease. Interestingly, flow cytometry analysis showed that the frequencies of pyroptotic MAIT cells, but not the frequencies of apoptotic MAIT cells, were increased significantly in patients with COVID-19, suggesting pyroptosis is one of leading causes of MAIT cell deaths during SARS-CoV-2 infection. Importantly, there were more clonal expansions of MAIT cells in severe cases than in moderate cases. Conclusions: The results of the present study suggest that MAIT cells are likely to be involved in the host immune response against SARS-CoV-2 infection. Simultaneously, the transcriptomic data from MAIT cells provides a deeper understanding of the immune pathogenesis of the disease.


Subject(s)
COVID-19/immunology , Mucosal-Associated Invariant T Cells/immunology , SARS-CoV-2/immunology , Transcriptome/genetics , Base Sequence , COVID-19/pathology , Gene Expression Profiling , Gene Expression Regulation/genetics , Gene Expression Regulation/immunology , Humans , Lymphocyte Activation/genetics , Pyroptosis/physiology , Sequence Analysis, RNA , Severity of Illness Index , VDJ Exons/genetics
11.
Nat Rev Immunol ; 21(11): 694-703, 2021 11.
Article in English | MEDLINE | ID: covidwho-1349668

ABSTRACT

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), results in life-threatening disease in a minority of patients, especially elderly people and those with co-morbidities such as obesity and diabetes. Severe disease is characterized by dysregulated cytokine release, pneumonia and acute lung injury, which can rapidly progress to acute respiratory distress syndrome, disseminated intravascular coagulation, multisystem failure and death. However, a mechanistic understanding of COVID-19 progression remains unclear. Here we review evidence that SARS-CoV-2 directly or indirectly activates inflammasomes, which are large multiprotein assemblies that are broadly responsive to pathogen-associated and stress-associated cellular insults, leading to secretion of the pleiotropic IL-1 family cytokines (IL-1ß and IL-18), and pyroptosis, an inflammatory form of cell death. We further discuss potential mechanisms of inflammasome activation and clinical efforts currently under way to suppress inflammation to prevent or ameliorate severe COVID-19.


Subject(s)
COVID-19/immunology , Inflammasomes/immunology , Animals , COVID-19/pathology , COVID-19/physiopathology , Cytokines/immunology , Humans , Inflammasomes/metabolism , Intracellular Signaling Peptides and Proteins/metabolism , Lung/immunology , Lung/pathology , Lung/virology , Phosphate-Binding Proteins/metabolism , Pyroptosis , Respiratory Distress Syndrome/immunology , Respiratory Distress Syndrome/virology , Severity of Illness Index
12.
Front Immunol ; 12: 631821, 2021.
Article in English | MEDLINE | ID: covidwho-1344260

ABSTRACT

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


Subject(s)
Cell Death/immunology , Neutrophils/pathology , Apoptosis/immunology , Apoptosis Regulatory Proteins/metabolism , Autophagy/immunology , Extracellular Traps/immunology , Extracellular Traps/metabolism , Free Radicals/metabolism , Humans , Necroptosis/immunology , Necrosis/immunology , Necrosis/metabolism , Neutrophil Activation , Neutrophils/immunology , Neutrophils/metabolism , Phagocytosis/immunology , Pyroptosis/immunology , Receptors, Death Domain/metabolism
13.
EMBO J ; 40(18): e108249, 2021 09 15.
Article in English | MEDLINE | ID: covidwho-1323479

ABSTRACT

SARS-CoV-2 is an emerging coronavirus that causes dysfunctions in multiple human cells and tissues. Studies have looked at the entry of SARS-CoV-2 into host cells mediated by the viral spike protein and human receptor ACE2. However, less is known about the cellular immune responses triggered by SARS-CoV-2 viral proteins. Here, we show that the nucleocapsid of SARS-CoV-2 inhibits host pyroptosis by blocking Gasdermin D (GSDMD) cleavage. SARS-CoV-2-infected monocytes show enhanced cellular interleukin-1ß (IL-1ß) expression, but reduced IL-1ß secretion. While SARS-CoV-2 infection promotes activation of the NLRP3 inflammasome and caspase-1, GSDMD cleavage and pyroptosis are inhibited in infected human monocytes. SARS-CoV-2 nucleocapsid protein associates with GSDMD in cells and inhibits GSDMD cleavage in vitro and in vivo. The nucleocapsid binds the GSDMD linker region and hinders GSDMD processing by caspase-1. These insights into how SARS-CoV-2 antagonizes cellular inflammatory responses may open new avenues for treating COVID-19 in the future.


Subject(s)
COVID-19/metabolism , Intracellular Signaling Peptides and Proteins/metabolism , Nucleocapsid/metabolism , Phosphate-Binding Proteins/metabolism , Pyroptosis/physiology , SARS-CoV-2/metabolism , Angiotensin-Converting Enzyme 2/immunology , Angiotensin-Converting Enzyme 2/metabolism , Animals , COVID-19/immunology , COVID-19/pathology , COVID-19/virology , Caspase 1/immunology , Caspase 1/metabolism , HEK293 Cells , Host-Pathogen Interactions , Humans , Inflammasomes/immunology , Inflammasomes/metabolism , Interleukin-1beta/immunology , Interleukin-1beta/metabolism , Intracellular Signaling Peptides and Proteins/immunology , Mice , Monocytes/metabolism , NLR Family, Pyrin Domain-Containing 3 Protein/immunology , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , Phosphate-Binding Proteins/immunology , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolism , THP-1 Cells
14.
Inflammopharmacology ; 29(4): 1049-1059, 2021 Aug.
Article in English | MEDLINE | ID: covidwho-1303332

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can enter the central nervous system and cause several neurological manifestations. Data from cerebrospinal fluid analyses and postmortem samples have been shown that SARS-CoV-2 has neuroinvasive properties. Therefore, ongoing studies have focused on mechanisms involved in neurotropism and neural injuries of SARS-CoV-2. The inflammasome is a part of the innate immune system that is responsible for the secretion and activation of several pro-inflammatory cytokines, such as interleukin-1ß, interleukin-6, and interleukin-18. Since cytokine storm has been known as a major mechanism followed by SARS-CoV-2, inflammasome may trigger an inflammatory form of lytic programmed cell death (pyroptosis) following SARS-CoV-2 infection and contribute to associated neurological complications. We reviewed and discussed the possible role of inflammasome and its consequence pyroptosis following coronavirus infections as potential mechanisms of neurotropism by SARS-CoV-2. Further studies, particularly postmortem analysis of brain samples obtained from COVID-19 patients, can shed light on the possible role of the inflammasome in neurotropism of SARS-CoV-2.


Subject(s)
COVID-19/metabolism , Central Nervous System/metabolism , Inflammasomes/metabolism , Pyroptosis/physiology , SARS-CoV-2/metabolism , Brain/immunology , Brain/metabolism , COVID-19/immunology , Central Nervous System/immunology , Humans , Inflammasomes/immunology , SARS-CoV-2/immunology
16.
Mol Med Rep ; 24(2)2021 Aug.
Article in English | MEDLINE | ID: covidwho-1271003

ABSTRACT

Coronavirus disease 2019 (COVID­19), caused by the severe acute respiratory syndrome coronavirus­2 (SARS­CoV­2), led to an outbreak of viral pneumonia in December 2019. The present study aimed to investigate the host inflammatory response signature­caused by SARS­CoV­2 in human corneal epithelial cells (HCECs). The expression level of angiotensin­converting enzyme 2 (ACE2) in the human cornea was determined via immunofluorescence. In vitro experiments were performed in HCECs stimulated with the SARS­CoV­2 spike protein. Moreover, the expression levels of ACE2, IL­8, TNF­α, IL­6, gasdermin D (GSDMD) and IL­1ß in HCECs were detected using reverse transcription­quantitative PCR and/or western blotting. It was identified that ACE2 was expressed in normal human corneal epithelium and HCECs cultured in vitro. Furthermore, the expression levels of IL­8, TNF­α and IL­6 in HCECs were decreased following SARS­CoV­2 spike protein stimulation, while the expression levels of GSDMD and IL­1ß were increased. In conclusion, the present results demonstrated that the SARS­CoV­2 spike protein suppressed the host inflammatory response and induced pyroptosis in HCECs. Therefore, blocking the ACE2 receptor in HCECs may reduce the infection rate of COVID­19.


Subject(s)
Epithelium, Corneal/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Adult , Aged , Angiotensin-Converting Enzyme 2/genetics , Angiotensin-Converting Enzyme 2/metabolism , Cells, Cultured , Cornea/cytology , Epithelial Cells/cytology , Epithelial Cells/metabolism , Epithelial Cells/virology , Epithelium, Corneal/virology , Female , Humans , Interleukin-1beta/genetics , Interleukin-1beta/metabolism , Interleukin-6/genetics , Interleukin-6/metabolism , Intracellular Signaling Peptides and Proteins/genetics , Intracellular Signaling Peptides and Proteins/metabolism , Male , Middle Aged , Phosphate-Binding Proteins/genetics , Phosphate-Binding Proteins/metabolism , Pyroptosis , Spike Glycoprotein, Coronavirus/genetics , Tumor Necrosis Factor-alpha/genetics , Tumor Necrosis Factor-alpha/metabolism , Up-Regulation
17.
Immunology ; 163(4): 377-388, 2021 08.
Article in English | MEDLINE | ID: covidwho-1247200

ABSTRACT

Apoptosis-associated speck-like protein containing a caspase recruit domain (ASC), encoded by PYCARD gene, is a 22 kDa small molecule, which aggregates into ASC specks during inflammasome activation. ASC protein is an adaptor protein present in several inflammasome complexes that performs several intra- and extracellular functions, in monomeric form or as ASC specks, during physiological and pathological processes related to inflammation and adaptive immunity. Extracellular ASC specks (eASC specks) released during cell death by pyroptosis can contribute as a danger signal to the propagation of inflammation via phagocytosis and activation of surrounding cells. ASC specks are found in the circulation of patients with chronic inflammatory diseases and have been considered as relevant blood biomarkers of inflammation. eASC amplifies the inflammatory signal, may induce the production of autoantibodies, transports molecules that bind to this complex, contributing to the generation of antibodies, and can induce the maturation of cytokines promoting the modelling of the adaptive immunity. Although several advances have been registered in the last 21 years, there are numerous unknown or enigmatic gaps in the understanding of the role of eASC specks in the organism. Here, we provide an overview about the ASC protein focusing on the probable roles of eASC specks in several diseases, up to the most recent studies concerning COVID-19.


Subject(s)
Adaptive Immunity , Alarmins/metabolism , CARD Signaling Adaptor Proteins/metabolism , Inflammasomes/metabolism , Inflammation Mediators/metabolism , Inflammation/metabolism , Animals , COVID-19/immunology , COVID-19/metabolism , COVID-19/pathology , COVID-19/virology , Host-Pathogen Interactions , Humans , Inflammasomes/immunology , Inflammation/immunology , Inflammation/pathology , Phagocytosis , Pyroptosis , SARS-CoV-2/immunology , SARS-CoV-2/pathogenicity , Signal Transduction
19.
Food Chem Toxicol ; 149: 112007, 2021 Mar.
Article in English | MEDLINE | ID: covidwho-1139498

ABSTRACT

Consistent gathering of immunotoxic substances on earth is a serious global issue affecting people under pathogenic stress. Organophosphates are among such hazardous compounds that are ubiquitous in nature. They fuel oxidative stress to impair antiviral immune response in living entities. Aside, organophosphates promote cytokine burst and pyroptosis in broncho-alveolar chambers leading to severe respiratory ailments. At present, we witness COVID-19 outbreak caused by SARS-CoV-2. Infection triggers cytokine storm coupled with inflammatory manifestations and pulmonary disorders in patients. Since organophosphate-exposure promotes necroinflammation and respiratory troubles hence during current pandemic situation, additional exposure to such chemicals can exacerbate inflammatory outcome and pulmonary maladies in patients, or pre-exposure to organophosphates might turn-out to be a risk factor for compromised immunity. Fortunately, antioxidants alleviate organophosphate-induced immunosuppression and hence under co-exposure circumstances, dietary intake of antioxidants would be beneficial to boost immunity against SARS-CoV-2 infection.


Subject(s)
COVID-19 , Environmental Exposure/adverse effects , Immunity/drug effects , Inflammation/etiology , Organophosphates/adverse effects , Oxidative Stress/drug effects , SARS-CoV-2/pathogenicity , Animals , Antioxidants/therapeutic use , COVID-19/immunology , COVID-19/virology , Cytokine Release Syndrome , Cytokines/metabolism , Humans , Inflammation/metabolism , Inflammation/prevention & control , Pandemics , Pesticides/adverse effects , Pyroptosis , Respiratory Tract Diseases/etiology , Virulence/drug effects
20.
Front Immunol ; 11: 592622, 2020.
Article in English | MEDLINE | ID: covidwho-1081192

ABSTRACT

SARS-CoV-2 causes the ongoing COVID-19 pandemic. Natural SARS-COV-2 infection has been detected in dogs, cats and tigers. However, the symptoms in canines and felines were mild. The underlying mechanisms are unknown. Excessive activation of inflammasome pathways can trigger cytokine storm and severe damage to host. In current study, we performed a comparative genomics study of key components of inflammasome and pyroptosis pathways in dogs, cats and tigers. Cats and tigers do not have AIM2 and NLRP1. Dogs do not contain AIM2, and encode a short form of NLRC4. The activation sites in GSDMB were absent in dogs, cats and tigers, while GSDME activation sites in cats and tigers were abolished. We propose that deficiencies of inflammasome and pyroptosis pathways might provide an evolutionary advantage against SARS-CoV-2 by reducing cytokine storm-induced host damage. Our findings will shed important lights on the mild symptoms in canines and felines infected with SARS-CoV-2.


Subject(s)
COVID-19/immunology , COVID-19/veterinary , Cat Diseases , Dog Diseases , Inflammasomes/immunology , Pyroptosis/immunology , Animals , Cat Diseases/immunology , Cat Diseases/virology , Cats , Cytokine Release Syndrome/genetics , Cytokine Release Syndrome/immunology , Dog Diseases/immunology , Dog Diseases/virology , Dogs , Genomics , Humans , Inflammasomes/genetics , Pyroptosis/genetics , SARS-CoV-2 , Tigers
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