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1.
Cells ; 11(10)2022 May 11.
Article in English | MEDLINE | ID: covidwho-1875501

ABSTRACT

DEAD/H-box proteins are the largest family of RNA helicases in mammalian genomes, and they are present in all kingdoms of life. Since their discovery in the late 1980s, DEAD/H-box family proteins have been a major focus of study. They have been found to play central roles in RNA metabolism, gene expression, signal transduction, programmed cell death, and the immune response to bacterial and viral infections. Aberrant functions of DEAD/H-box proteins have been implicated in a wide range of human diseases that include cancer, neurodegeneration, and inherited genetic disorders. In this review, we provide a historical context and discuss the molecular functions of DEAD/H-box proteins, highlighting the recent discoveries linking their dysregulation to human diseases. We will also discuss the state of knowledge regarding two specific DEAD/H-box proteins that have critical roles in immune responses and programmed cell death, DDX3X and DDX58, also known as RIG-I. Given their importance in homeostasis and disease, an improved understanding of DEAD/H-box protein biology and protein-protein interactions will be critical for informing strategies to counteract the pathogenesis associated with several human diseases.


Subject(s)
DEAD-box RNA Helicases , RNA , Animals , Cell Death , Cell Differentiation , DEAD-box RNA Helicases/metabolism , DNA Helicases , Humans , Inflammation , Mammals/metabolism , RNA/metabolism
2.
Sci Immunol ; : eabo6294, 2022 May 19.
Article in English | MEDLINE | ID: covidwho-1854224

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for coronavirus disease 2019 (COVID-19), continues to cause significant morbidity and mortality in the ongoing global pandemic. Understanding the fundamental mechanisms that govern innate immune and inflammatory responses during SARS-CoV-2 infection is critical for developing effective therapeutic strategies. While IFN-based therapies are generally expected to be beneficial during viral infection, clinical trials in COVID-19 have shown limited efficacy and potential detrimental effects of IFN treatment during SARS-CoV-2 infection. However, the underlying mechanisms responsible for this failure remain unknown. In this study, we found that IFN induced ZBP1-mediated inflammatory cell death, PANoptosis, in human and murine macrophages and in the lungs of mice infected with ß-coronaviruses, including SARS-CoV-2 and mouse hepatitis virus (MHV). In patients with COVID-19, expression of the innate immune sensor ZBP1 was increased in immune cells from those who succumbed to the disease compared with those who recovered, further suggesting a link between ZBP1 and pathology. In mice, IFN-ß treatment following ß-coronavirus infection increased lethality, and genetic deletion of Zbp1 or its Zα domain suppressed cell death and protected the mice from IFN-mediated lethality during ß-coronavirus infection. Overall, our results identify that ZBP1 induced during coronavirus infection limits the efficacy of IFN therapy by driving inflammatory cell death and lethality. Therefore, inhibiting ZBP1 activity may improve the efficacy of IFN therapy, paving the way for the development of new and critically needed therapeutics for COVID-19 as well as other infections and inflammatory conditions where IFN-mediated cell death and pathology occur.

3.
Cancers (Basel) ; 14(4)2022 Feb 12.
Article in English | MEDLINE | ID: covidwho-1715121

ABSTRACT

Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide, and innate immune responses and inflammation are known to affect the course of disease. Interferon (IFN) signaling in particular is critical for modulating inflammation-associated diseases including CRC. While the effects of IFN signaling in CRC have been studied, results have been conflicting. Furthermore, individual molecules in the IFN pathway that could be therapeutically targeted have distinct functions, with many of their diverse roles in CRC remaining unclear. Here, we found that IRF9 had an oncogenic effect in CRC; loss of IRF9 reduced tumorigenesis in both azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced and spontaneous CRC models. IRF9 also reduced DSS-induced colitis and inflammation in the colon, but it had no effect on the NF-κB and MAPK signaling activation. Instead, IRF9 enhanced the transcription and production of the inflammatory cytokine IL-6. By promoting IL-6 release, IRF9 drove the activation of pro-oncogenic STAT3 signaling in the colon. Overall, our study found that IRF9 promoted the development of CRC via modulation of the IL-6/STAT3 signaling axis, identifying multiple potential targets and suggesting new therapeutic strategies for the treatment of CRC.

4.
Nat Immunol ; 23(2): 165-176, 2022 02.
Article in English | MEDLINE | ID: covidwho-1671597

ABSTRACT

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus (SARS-CoV)-2, continues to cause substantial morbidity and mortality. While most infections are mild, some patients experience severe and potentially fatal systemic inflammation, tissue damage, cytokine storm and acute respiratory distress syndrome. The innate immune system acts as the first line of defense, sensing the virus through pattern recognition receptors and activating inflammatory pathways that promote viral clearance. Here, we discuss innate immune processes involved in SARS-CoV-2 recognition and the resultant inflammation. Improved understanding of how the innate immune system detects and responds to SARS-CoV-2 will help identify targeted therapeutic modalities that mitigate severe disease and improve patient outcomes.


Subject(s)
COVID-19/immunology , Immunity, Innate , SARS-CoV-2/immunology , Animals , COVID-19/metabolism , COVID-19/virology , Cytokines/immunology , Cytokines/metabolism , Humans , Immune Evasion , Inflammasomes/immunology , Inflammasomes/metabolism , NLR Proteins/immunology , NLR Proteins/metabolism , Receptors, Pattern Recognition/immunology , Receptors, Pattern Recognition/metabolism , SARS-CoV-2/pathogenicity , Signal Transduction , Toll-Like Receptors/immunology , Toll-Like Receptors/metabolism , Virus Internalization
5.
J Mol Biol ; 434(4): 167249, 2022 02 28.
Article in English | MEDLINE | ID: covidwho-1415577

ABSTRACT

In the past decade, emerging viral outbreaks like SARS-CoV-2, Zika and Ebola have presented major challenges to the global health system. Viruses are unique pathogens in that they fully rely on the host cell to complete their lifecycle and potentiate disease. Therefore, programmed cell death (PCD), a key component of the host innate immune response, is an effective strategy for the host cell to curb viral spread. The most well-established PCD pathways, pyroptosis, apoptosis and necroptosis, can be activated in response to viruses. Recently, extensive crosstalk between PCD pathways has been identified, and there is evidence that molecules from all three PCD pathways can be activated during virus infection. These findings have led to the emergence of the concept of PANoptosis, defined as an inflammatory PCD pathway regulated by the PANoptosome complex with key features of pyroptosis, apoptosis, and/or necroptosis that cannot be accounted for by any of these three PCD pathways alone. While PCD is important to eliminate infected cells, many viruses are equipped to hijack host PCD pathways to benefit their own propagation and subvert host defense, and PCD can also lead to the production of inflammatory cytokines and inflammation. Therefore, PANoptosis induced by viral infection contributes to either host defense or viral pathogenesis in context-specific ways. In this review, we will discuss the multi-faceted roles of PCD pathways in controlling viral infections.


Subject(s)
Apoptosis , Virus Diseases/pathology , Animals , Humans , Models, Biological , Necroptosis , Pyroptosis
6.
Trends Immunol ; 42(8): 681-705, 2021 08.
Article in English | MEDLINE | ID: covidwho-1292759

ABSTRACT

Cytokine storm syndrome (CSS) has generally been described as a collection of clinical manifestations resulting from an overactivated immune system. Cytokine storms (CSs) are associated with various pathologies, as observed in infectious diseases, certain acquired or inherited immunodeficiencies and autoinflammatory diseases, or following therapeutic interventions. Despite the role of CS in tissue damage and multiorgan failure, a systematic understanding of its underlying molecular mechanisms is lacking. Recent studies demonstrate a positive feedback loop between cytokine release and cell death pathways; certain cytokines, pathogen-associated molecular patterns (PAMPs), and damage-associated molecular patterns (DAMPs), can activate inflammatory cell death, leading to further cytokine secretion. Here, we discuss recent progress in innate immunity and inflammatory cell death, providing insights into the cellular and molecular mechanisms of CSs and therapeutics that might quell ensuing life-threatening effects.


Subject(s)
COVID-19 , Cytokine Release Syndrome , Cytokines , Humans , Immune System , Pathogen-Associated Molecular Pattern Molecules
7.
Mol Cell ; 81(11): 2261-2265, 2021 06 03.
Article in English | MEDLINE | ID: covidwho-1246090

ABSTRACT

COVID-19 altered our lives and pushed scientific research to operate at breakneck speed, leading to significant breakthroughs in record time. We asked experts in the field about the challenges they faced in transitioning, rapidly but safely, to working on the virus while navigating the shutdown. Their voices converge on the importance of teamwork, forging new collaborations, and working toward a shared goal.


Subject(s)
Biomedical Research , COVID-19/epidemiology , COVID-19/prevention & control , Pandemics , Quarantine , SARS-CoV-2 , Humans , Poetry as Topic
8.
Nat Immunol ; 22(7): 829-838, 2021 07.
Article in English | MEDLINE | ID: covidwho-1220263

ABSTRACT

The innate immune response is critical for recognizing and controlling infections through the release of cytokines and chemokines. However, severe pathology during some infections, including SARS-CoV-2, is driven by hyperactive cytokine release, or a cytokine storm. The innate sensors that activate production of proinflammatory cytokines and chemokines during COVID-19 remain poorly characterized. In the present study, we show that both TLR2 and MYD88 expression were associated with COVID-19 disease severity. Mechanistically, TLR2 and Myd88 were required for ß-coronavirus-induced inflammatory responses, and TLR2-dependent signaling induced the production of proinflammatory cytokines during coronavirus infection independent of viral entry. TLR2 sensed the SARS-CoV-2 envelope protein as its ligand. In addition, blocking TLR2 signaling in vivo provided protection against the pathogenesis of SARS-CoV-2 infection. Overall, our study provides a critical understanding of the molecular mechanism of ß-coronavirus sensing and inflammatory cytokine production, which opens new avenues for therapeutic strategies to counteract the ongoing COVID-19 pandemic.


Subject(s)
COVID-19/immunology , Coronavirus Envelope Proteins/metabolism , Cytokine Release Syndrome/immunology , SARS-CoV-2/immunology , Toll-Like Receptor 2/metabolism , Animals , COVID-19/complications , COVID-19/diagnosis , COVID-19/drug therapy , COVID-19/virology , Chlorocebus aethiops , Cytokine Release Syndrome/diagnosis , Cytokines/metabolism , Disease Models, Animal , Female , Gene Expression Profiling , Humans , Immunity, Innate/drug effects , Leukocytes, Mononuclear , Macrophages , Male , Mice , Mice, Knockout , Myeloid Differentiation Factor 88/genetics , Myeloid Differentiation Factor 88/metabolism , Primary Cell Culture , SARS-CoV-2/metabolism , SARS-CoV-2/pathogenicity , Severity of Illness Index , Signal Transduction/drug effects , Signal Transduction/genetics , Signal Transduction/immunology , Toll-Like Receptor 2/antagonists & inhibitors , Toll-Like Receptor 2/genetics , Vero Cells
9.
Cell ; 184(1): 149-168.e17, 2021 01 07.
Article in English | MEDLINE | ID: covidwho-1064910

ABSTRACT

COVID-19 is characterized by excessive production of pro-inflammatory cytokines and acute lung damage associated with patient mortality. While multiple inflammatory cytokines are produced by innate immune cells during SARS-CoV-2 infection, we found that only the combination of TNF-α and IFN-γ induced inflammatory cell death characterized by inflammatory cell death, PANoptosis. Mechanistically, TNF-α and IFN-γ co-treatment activated the JAK/STAT1/IRF1 axis, inducing nitric oxide production and driving caspase-8/FADD-mediated PANoptosis. TNF-α and IFN-γ caused a lethal cytokine shock in mice that mirrors the tissue damage and inflammation of COVID-19, and inhibiting PANoptosis protected mice from this pathology and death. Furthermore, treating with neutralizing antibodies against TNF-α and IFN-γ protected mice from mortality during SARS-CoV-2 infection, sepsis, hemophagocytic lymphohistiocytosis, and cytokine shock. Collectively, our findings suggest that blocking the cytokine-mediated inflammatory cell death signaling pathway identified here may benefit patients with COVID-19 or other infectious and autoinflammatory diseases by limiting tissue damage/inflammation.


Subject(s)
COVID-19/immunology , COVID-19/pathology , Cytokine Release Syndrome/immunology , Cytokine Release Syndrome/pathology , Interferon-gamma/immunology , Tumor Necrosis Factor-alpha/immunology , Animals , Antibodies, Neutralizing/administration & dosage , Cell Death , Disease Models, Animal , Female , Human Umbilical Vein Endothelial Cells , Humans , Inflammation/immunology , Inflammation/pathology , Lymphohistiocytosis, Hemophagocytic/chemically induced , Male , Mice , Mice, Transgenic , THP-1 Cells
10.
bioRxiv ; 2020 Nov 13.
Article in English | MEDLINE | ID: covidwho-915984

ABSTRACT

The COVID-19 pandemic has caused significant morbidity and mortality. Currently, there is a critical shortage of proven treatment options and an urgent need to understand the pathogenesis of multi-organ failure and lung damage. Cytokine storm is associated with severe inflammation and organ damage during COVID-19. However, a detailed molecular pathway defining this cytokine storm is lacking, and gaining mechanistic understanding of how SARS-CoV-2 elicits a hyperactive inflammatory response is critical to develop effective therapeutics. Of the multiple inflammatory cytokines produced by innate immune cells during SARS-CoV-2 infection, we found that the combined production of TNF-α and IFN-γ specifically induced inflammatory cell death, PANoptosis, characterized by gasdermin-mediated pyroptosis, caspase-8-mediated apoptosis, and MLKL-mediated necroptosis. Deletion of pyroptosis, apoptosis, or necroptosis mediators individually was not sufficient to protect against cell death. However, cells deficient in both RIPK3 and caspase-8 or RIPK3 and FADD were resistant to this cell death. Mechanistically, the JAK/STAT1/IRF1 axis activated by TNF-α and IFN-γ co-treatment induced iNOS for the production of nitric oxide. Pharmacological and genetic deletion of this pathway inhibited pyroptosis, apoptosis, and necroptosis in macrophages. Moreover, inhibition of PANoptosis protected mice from TNF-α and IFN-γ-induced lethal cytokine shock that mirrors the pathological symptoms of COVID-19. In vivo neutralization of both TNF-α and IFN-γ in multiple disease models associated with cytokine storm showed that this treatment provided substantial protection against not only SARS-CoV-2 infection, but also sepsis, hemophagocytic lymphohistiocytosis, and cytokine shock models, demonstrating the broad physiological relevance of this mechanism. Collectively, our findings suggest that blocking the cytokine-mediated inflammatory cell death signaling pathway identified here may benefit patients with COVID-19 or other cytokine storm-driven syndromes by limiting inflammation and tissue damage. The findings also provide a molecular and mechanistic description for the term cytokine storm. Additionally, these results open new avenues for the treatment of other infectious and autoinflammatory diseases and cancers where TNF-α and IFN-γ synergism play key pathological roles.

11.
Trends Immunol ; 41(12): 1083-1099, 2020 12.
Article in English | MEDLINE | ID: covidwho-866780

ABSTRACT

The innate immune system acts as the first line of defense against pathogens, including coronaviruses (CoVs). Severe acute respiratory syndrome (SARS)-CoV and Middle East respiratory syndrome (MERS)-CoV are epidemic zoonotic CoVs that emerged at the beginning of the 21st century. The recently emerged virus SARS-CoV-2 is a novel strain of CoV that has caused the coronavirus 2019 (COVID-19) pandemic. Scientific advancements made by studying the SARS-CoV and MERS-CoV outbreaks have provided a foundation for understanding pathogenesis and innate immunity against SARS-CoV-2. In this review, we focus on our present understanding of innate immune responses, inflammasome activation, inflammatory cell death pathways, and cytokine secretion during SARS-CoV, MERS-CoV, and SARS-CoV-2 infection. We also discuss how the pathogenesis of these viruses influences these biological processes.


Subject(s)
COVID-19/immunology , Cell Death/immunology , Cytokines/immunology , Immunity, Innate/immunology , Inflammasomes/immunology , SARS-CoV-2/immunology , Animals , Humans
12.
J Biol Chem ; 295(41): 14040-14052, 2020 10 09.
Article in English | MEDLINE | ID: covidwho-704089

ABSTRACT

Coronaviruses have caused several zoonotic infections in the past two decades, leading to significant morbidity and mortality globally. Balanced regulation of cell death and inflammatory immune responses is essential to promote protection against coronavirus infection; however, the underlying mechanisms that control these processes remain to be resolved. Here we demonstrate that infection with the murine coronavirus mouse hepatitis virus (MHV) activated the NLRP3 inflammasome and inflammatory cell death in the form of PANoptosis. Deleting NLRP3 inflammasome components or the downstream cell death executioner gasdermin D (GSDMD) led to an initial reduction in cell death followed by a robust increase in the incidence of caspase-8- and receptor-interacting serine/threonine-protein kinase 3 (RIPK3)-mediated inflammatory cell deathafter coronavirus infection. Additionally, loss of GSDMD promoted robust NLRP3 inflammasome activation. Moreover, the amounts of some cytokines released during coronavirus infection were significantly altered in the absence of GSDMD. Altogether, our findings show that inflammatory cell death, PANoptosis, is induced by coronavirus infection and that impaired NLRP3 inflammasome function or pyroptosis can lead to negative consequences for the host. These findings may have important implications for studies of coronavirus-induced disease.


Subject(s)
Caspase 8/metabolism , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , Pyroptosis , Receptor-Interacting Protein Serine-Threonine Kinases/metabolism , Animals , Cells, Cultured , Coronavirus/physiology , Coronavirus Infections/metabolism , Coronavirus Infections/pathology , Coronavirus Infections/veterinary , Cytokines/metabolism , Inflammasomes/metabolism , Intracellular Signaling Peptides and Proteins/genetics , Intracellular Signaling Peptides and Proteins/metabolism , Macrophages/cytology , Macrophages/metabolism , Macrophages/virology , Mice , Mice, Inbred C57BL , Mice, Knockout , NLR Family, Pyrin Domain-Containing 3 Protein/genetics , Necroptosis , Phosphate-Binding Proteins/genetics , Phosphate-Binding Proteins/metabolism
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