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1.
Int J Mol Sci ; 22(16)2021 Aug 23.
Article in English | MEDLINE | ID: covidwho-1662694

ABSTRACT

Polyethyleneimine (PEI) induced immune responses were investigated in human bronchial epithelial (hBE) cells and mice. PEI rapidly induced ATP release from hBE cells and pretreatment with glutathione (GSH) blocked the response. PEI activated two conductive pathways, VDAC-1 and pannexin 1, which completely accounted for ATP efflux across the plasma membrane. Moreover, PEI increased intracellular Ca2+ concentration ([Ca2+]i), which was reduced by the pannexin 1 inhibitor, 10Panx (50 µM), the VDAC-1 inhibitor, DIDS (100 µM), and was nearly abolished by pretreatment with GSH (5 mM). The increase in [Ca2+]i involved Ca2+ uptake through two pathways, one blocked by oxidized ATP (oATP, 300 µM) and another that was blocked by the TRPV-1 antagonist A784168 (100 nM). PEI stimulation also increased IL-33 mRNA expression and protein secretion. In vivo experiments showed that acute (4.5 h) PEI exposure stimulated secretion of Th2 cytokines (IL-5 and IL-13) into bronchoalveolar lavage (BAL) fluid. Conjugation of PEI with ovalbumin also induced eosinophil recruitment and secretion of IL-5 and IL-13 into BAL fluid, which was inhibited in IL-33 receptor (ST2) deficient mice. In conclusion, PEI-induced oxidative stress stimulated type 2 immune responses by activating ATP-dependent Ca2+ uptake leading to IL-33 secretion, similar to allergens derived from Alternaria.


Subject(s)
Adenosine Triphosphate/immunology , Epithelial Cells/drug effects , Epithelial Cells/immunology , Immunity/drug effects , Nanoparticles/administration & dosage , Oxidative Stress/drug effects , Polyethyleneimine/pharmacology , Allergens/immunology , Animals , Calcium/immunology , Cells, Cultured , Cytokines/immunology , Female , Humans , Immunity/immunology , Mice , Mice, Inbred BALB C , Oxidative Stress/immunology , RNA, Messenger/immunology , Respiratory Mucosa/drug effects , Respiratory Mucosa/immunology
2.
PLoS Biol ; 19(12): e3001065, 2021 12.
Article in English | MEDLINE | ID: covidwho-1594053

ABSTRACT

The pandemic spread of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the etiological agent of Coronavirus Disease 2019 (COVID-19), represents an ongoing international health crisis. A key symptom of SARS-CoV-2 infection is the onset of fever, with a hyperthermic temperature range of 38 to 41°C. Fever is an evolutionarily conserved host response to microbial infection that can influence the outcome of viral pathogenicity and regulation of host innate and adaptive immune responses. However, it remains to be determined what effect elevated temperature has on SARS-CoV-2 replication. Utilizing a three-dimensional (3D) air-liquid interface (ALI) model that closely mimics the natural tissue physiology of SARS-CoV-2 infection in the respiratory airway, we identify tissue temperature to play an important role in the regulation of SARS-CoV-2 infection. Respiratory tissue incubated at 40°C remained permissive to SARS-CoV-2 entry but refractory to viral transcription, leading to significantly reduced levels of viral RNA replication and apical shedding of infectious virus. We identify tissue temperature to play an important role in the differential regulation of epithelial host responses to SARS-CoV-2 infection that impact upon multiple pathways, including intracellular immune regulation, without disruption to general transcription or epithelium integrity. We present the first evidence that febrile temperatures associated with COVID-19 inhibit SARS-CoV-2 replication in respiratory epithelia. Our data identify an important role for tissue temperature in the epithelial restriction of SARS-CoV-2 independently of canonical interferon (IFN)-mediated antiviral immune defenses.


Subject(s)
Epithelial Cells/immunology , Hot Temperature , Immunity, Innate/immunology , Interferons/immunology , Respiratory Mucosa/immunology , SARS-CoV-2/immunology , Virus Replication/immunology , Adolescent , Animals , COVID-19/genetics , COVID-19/immunology , COVID-19/virology , Chlorocebus aethiops , Epithelial Cells/metabolism , Epithelial Cells/virology , Female , Gene Expression Profiling/methods , Host-Pathogen Interactions/genetics , Host-Pathogen Interactions/immunology , Humans , Immunity, Innate/genetics , Interferons/genetics , Interferons/metabolism , Male , Middle Aged , Models, Biological , RNA-Seq/methods , Respiratory Mucosa/metabolism , Respiratory Mucosa/virology , SARS-CoV-2/genetics , SARS-CoV-2/physiology , Tissue Culture Techniques , Vero Cells , Virus Replication/genetics , Virus Replication/physiology
3.
Nat Immunol ; 23(1): 23-32, 2022 01.
Article in English | MEDLINE | ID: covidwho-1585822

ABSTRACT

Systemic immune cell dynamics during coronavirus disease 2019 (COVID-19) are extensively documented, but these are less well studied in the (upper) respiratory tract, where severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replicates1-6. Here, we characterized nasal and systemic immune cells in individuals with COVID-19 who were hospitalized or convalescent and compared the immune cells to those seen in healthy donors. We observed increased nasal granulocytes, monocytes, CD11c+ natural killer (NK) cells and CD4+ T effector cells during acute COVID-19. The mucosal proinflammatory populations positively associated with peripheral blood human leukocyte antigen (HLA)-DRlow monocytes, CD38+PD1+CD4+ T effector (Teff) cells and plasmablasts. However, there was no general lymphopenia in nasal mucosa, unlike in peripheral blood. Moreover, nasal neutrophils negatively associated with oxygen saturation levels in blood. Following convalescence, nasal immune cells mostly normalized, except for CD127+ granulocytes and CD38+CD8+ tissue-resident memory T cells (TRM). SARS-CoV-2-specific CD8+ T cells persisted at least 2 months after viral clearance in the nasal mucosa, indicating that COVID-19 has both transient and long-term effects on upper respiratory tract immune responses.


Subject(s)
CD4-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/immunology , Nasopharynx/immunology , Nose/cytology , Respiratory Mucosa/immunology , SARS-CoV-2/immunology , Antibodies, Viral/blood , COVID-19/immunology , COVID-19/pathology , Granulocytes/immunology , HLA-DR Antigens/metabolism , Humans , Killer Cells, Natural/immunology , Monocytes/immunology , Nasopharynx/cytology , Nasopharynx/virology , Neutrophils/immunology , Nose/immunology , Nose/virology , Prospective Studies , Respiratory Mucosa/cytology , Respiratory Mucosa/virology
5.
Front Immunol ; 12: 672523, 2021.
Article in English | MEDLINE | ID: covidwho-1389182

ABSTRACT

Lower respiratory infections are among the leading causes of morbidity and mortality worldwide. These potentially deadly infections are further exacerbated due to the growing incidence of antimicrobial resistance. To combat these infections there is a need to better understand immune mechanisms that promote microbial clearance. This need in the context of lung infections has been further heightened with the emergence of SARS-CoV-2. Group 3 innate lymphoid cells (ILC3s) are a recently discovered tissue resident innate immune cell found at mucosal sites that respond rapidly in the event of an infection. ILC3s have clear roles in regulating mucosal immunity and tissue homeostasis in the intestine, though the immunological functions in lungs remain unclear. It has been demonstrated in both viral and bacterial pneumonia that stimulated ILC3s secrete the cytokines IL-17 and IL-22 to promote both microbial clearance as well as tissue repair. In this review, we will evaluate regulation of ILC3s during inflammation and discuss recent studies that examine ILC3 function in the context of both bacterial and viral pulmonary infections.


Subject(s)
COVID-19/immunology , Immunity, Mucosal/immunology , Lymphocytes/immunology , Pneumonia, Bacterial/immunology , Respiratory Mucosa/immunology , SARS-CoV-2/immunology , Bacteria/immunology , COVID-19/mortality , COVID-19/pathology , Immunity, Innate/immunology , Inflammation/immunology , Interleukin-17/metabolism , Interleukins/metabolism , Lung/immunology , Lymphocyte Activation/immunology , Respiratory Mucosa/cytology
6.
Viruses ; 13(9)2021 08 28.
Article in English | MEDLINE | ID: covidwho-1374539

ABSTRACT

Angiotensin converting enzyme 2 (ACE2) is a host ectopeptidase and the receptor for the SARS-CoV-2 virus, albeit virus-ACE2 interaction goes far beyond viral entry into target cells. Controversial data exists linking viral infection to changes in ACE2 expression and function, which might influence the subsequent induction of an inflammatory response. Here, we tested the significance of soluble ACE2 enzymatic activity longitudinally in nasopharyngeal swabs and plasma samples of SARS-CoV-2 infected patients, along with the induction of inflammatory cytokines. Release of soluble functional ACE2 increases upon SARS-CoV-2 infection in swabs and plasma of infected patients, albeit rapidly decreasing during infection course in parallel with ACE2 gene expression. Similarly, SARS-CoV-2 infection also induced the expression of inflammatory cytokines. These changes positively correlated with the viral load. Overall, our results demonstrate the existence of mechanisms by which SARS-CoV-2 modulates ACE2 expression and function, intracellular viral sensing and subsequent inflammatory response, offering new insights into ACE2 dynamics in the human upper respiratory tract and pointing towards soluble ACE2 levels as a putative early biomarker of infection severity.


Subject(s)
Angiotensin-Converting Enzyme 2/metabolism , COVID-19/metabolism , COVID-19/virology , Host-Pathogen Interactions , SARS-CoV-2/physiology , Angiotensin-Converting Enzyme 2/genetics , Biomarkers , COVID-19/diagnosis , COVID-19/immunology , Cytokines/blood , Cytokines/genetics , Cytokines/metabolism , Gene Expression , Host-Pathogen Interactions/immunology , Humans , Respiratory Mucosa/immunology , Respiratory Mucosa/metabolism , Respiratory Mucosa/pathology , Respiratory Mucosa/virology , SARS-CoV-2/isolation & purification , Viral Load
7.
Viruses ; 13(8)2021 08 12.
Article in English | MEDLINE | ID: covidwho-1355052

ABSTRACT

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019 (COVID-19), a global pandemic characterized by an exaggerated immune response and respiratory illness. Age (>60 years) is a significant risk factor for developing severe COVID-19. To better understand the host response of the aged airway epithelium to SARS-CoV-2 infection, we performed an in vitro study using primary human bronchial epithelial cells from donors >67 years of age differentiated on an air-liquid interface culture. We demonstrate that SARS-CoV-2 infection leads to early induction of a proinflammatory response and a delayed interferon response. In addition, we observed changes in the genes and pathways associated with cell death and senescence throughout infection. In summary, our study provides new and important insights into the temporal kinetics of the airway epithelial innate immune response to SARS-CoV-2 in older individuals.


Subject(s)
Bronchi/immunology , Bronchi/virology , Immunity, Innate , Respiratory Mucosa/immunology , Respiratory Mucosa/virology , SARS-CoV-2/immunology , Aged , Aging/immunology , Bronchi/cytology , Bronchi/metabolism , COVID-19/immunology , Cell Death/genetics , Cells, Cultured , Cellular Senescence/genetics , Cytokines/biosynthesis , Cytokines/genetics , Epithelial Cells/immunology , Epithelial Cells/metabolism , Epithelial Cells/virology , Female , Humans , Inflammation , Interferons/biosynthesis , Interferons/genetics , Male , RNA-Seq , Respiratory Mucosa/cytology , Respiratory Mucosa/metabolism , SARS-CoV-2/physiology , Signal Transduction/genetics
8.
EBioMedicine ; 70: 103500, 2021 Aug.
Article in English | MEDLINE | ID: covidwho-1322074

ABSTRACT

BACKGROUND: The outbreak of Coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 infection has become a global health emergency. We aim to decipher SARS-CoV-2 infected cell types, the consequent host immune response and their interplay in lung of COVID-19 patients. METHODS: We analyzed single-cell RNA sequencing (scRNA-seq) data of bronchoalveolar lavage fluid (BALF) samples from 10 healthy donors, 6 severe COVID-19 patients and 3 mild recovered patients. The expressions of SARS-CoV-2 receptors (ACE2 and TMPRSS2) were examined among different cell types. The immune cells infiltration patterns, their expression profiles, and interplays between immune cells and SARS-CoV-2 target cells were further investigated. FINDINGS: Compared to healthy controls, ACE2 and TMPRSS2 expressions were significantly higher in lung epithelial cells of COVID-19 patients, in particular club and ciliated cells. SARS-CoV-2 activated pro-inflammatory genes and interferon/cytokine signaling in these cells. In severe COVID-19 patients, significantly higher neutrophil, but lower macrophage in lung was observed along with markedly increased cytokines expression compared with healthy controls and mild patients. By contrast, neutrophil and macrophage returned to normal level whilst more T and NK cells accumulation were observed in mild patients. Moreover, SARS-CoV-2 infection altered the community interplays of lung epithelial and immune cells: interactions between the club and immune cells were higher in COVID-19 patients compared to healthy donors; on the other hand, immune-immune cells interactions appeared the strongest in mild patients. INTERPRETATION: SARS-CoV-2 could infect lung epithelium, alter communication patterns between lung epithelial cells and immune system, and drive dysregulated host immune response in COVID-19 patients. FUNDING: This project was supported by National Key R&D Program of China (No. 2018YFC1315000/2018YFC1315004), Science and Technology Program Grant Shenzhen (JCYJ20170413161534162), HMRF Hong Kong (17160862), RGC-CRF Hong Kong (C4039-19G), RGC-GRF Hong Kong (14163817), Vice-Chancellor's Discretionary Fund CUHK and CUHK direct grant, Shenzhen Virtual University Park Support Scheme to CUHK Shenzhen Research Institute.


Subject(s)
COVID-19/immunology , Epithelial Cells/immunology , Inflammation/immunology , Lung/immunology , SARS-CoV-2/immunology , Signal Transduction/immunology , A549 Cells , Angiotensin-Converting Enzyme 2/immunology , COVID-19/virology , Case-Control Studies , Cell Line , Cell Line, Tumor , Cytokines/immunology , Humans , Inflammation/virology , Killer Cells, Natural/immunology , Lung/virology , Macrophages/immunology , Neutrophils/immunology , Respiratory Mucosa/immunology , Respiratory Mucosa/virology , Serine Endopeptidases/immunology , T-Lymphocytes/immunology
9.
Int J Mol Sci ; 22(8)2021 Apr 08.
Article in English | MEDLINE | ID: covidwho-1299441

ABSTRACT

Pneumonia due to respiratory infection with most prominently bacteria, but also viruses, fungi, or parasites is the leading cause of death worldwide among all infectious disease in both adults and infants. The introduction of modern antibiotic treatment regimens and vaccine strategies has helped to lower the burden of bacterial pneumonia, yet due to the unavailability or refusal of vaccines and antimicrobials in parts of the global population, the rise of multidrug resistant pathogens, and high fatality rates even in patients treated with appropriate antibiotics pneumonia remains a global threat. As such, a better understanding of pathogen virulence on the one, and the development of innovative vaccine strategies on the other hand are once again in dire need in the perennial fight of men against microbes. Recent data show that the secretome of bacteria consists not only of soluble mediators of virulence but also to a significant proportion of extracellular vesicles-lipid bilayer-delimited particles that form integral mediators of intercellular communication. Extracellular vesicles are released from cells of all kinds of organisms, including both Gram-negative and Gram-positive bacteria in which case they are commonly termed outer membrane vesicles (OMVs) and membrane vesicles (MVs), respectively. (O)MVs can trigger inflammatory responses to specific pathogens including S. pneumonia, P. aeruginosa, and L. pneumophila and as such, mediate bacterial virulence in pneumonia by challenging the host respiratory epithelium and cellular and humoral immunity. In parallel, however, (O)MVs have recently emerged as auspicious vaccine candidates due to their natural antigenicity and favorable biochemical properties. First studies highlight the efficacy of such vaccines in animal models exposed to (O)MVs from B. pertussis, S. pneumoniae, A. baumannii, and K. pneumoniae. An advanced and balanced recognition of both the detrimental effects of (O)MVs and their immunogenic potential could pave the way to novel treatment strategies in pneumonia and effective preventive approaches.


Subject(s)
Bacteria/metabolism , Bacterial Outer Membrane/metabolism , Extracellular Vesicles/metabolism , Pneumonia, Bacterial/microbiology , Adaptive Immunity , Animals , Antigens, Bacterial/immunology , Bacteria/immunology , Bacterial Outer Membrane/immunology , Bacterial Vaccines/immunology , Host-Pathogen Interactions/immunology , Humans , Pneumonia, Bacterial/immunology , Pneumonia, Bacterial/prevention & control , Respiratory Mucosa/immunology , Respiratory Mucosa/microbiology , Respiratory Tract Infections/immunology , Respiratory Tract Infections/microbiology , Respiratory Tract Infections/prevention & control , Virulence
10.
J Allergy Clin Immunol ; 147(6): 2083-2097.e6, 2021 06.
Article in English | MEDLINE | ID: covidwho-1272498

ABSTRACT

BACKGROUND: Excessive inflammation triggered by a hitherto undescribed mechanism is a hallmark of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and is associated with enhanced pathogenicity and mortality. OBJECTIVE: Complement hyperactivation promotes lung injury and was observed in patients suffering from Middle East respiratory syndrome-related coronavirus, SARS-CoV-1, and SARS-CoV-2 infections. Therefore, we investigated the very first interactions of primary human airway epithelial cells on exposure to SARS-CoV-2 in terms of complement component 3 (C3)-mediated effects. METHODS: For this, we used highly differentiated primary human 3-dimensional tissue models infected with SARS-CoV-2 patient isolates. On infection, viral load, viral infectivity, intracellular complement activation, inflammatory mechanisms, and tissue destruction were analyzed by real-time RT-PCR, high content screening, plaque assays, luminex analyses, and transepithelial electrical resistance measurements. RESULTS: Here, we show that primary normal human bronchial and small airway epithelial cells respond to SARS-CoV-2 infection by an inflated local C3 mobilization. SARS-CoV-2 infection resulted in exaggerated intracellular complement activation and destruction of the epithelial integrity in monolayer cultures of primary human airway cells and highly differentiated, pseudostratified, mucus-producing, ciliated respiratory tissue models. SARS-CoV-2-infected 3-dimensional cultures secreted significantly higher levels of C3a and the proinflammatory cytokines IL-6, monocyte chemoattractant protein 1, IL-1α, and RANTES. CONCLUSIONS: Crucially, we illustrate here for the first time that targeting the anaphylotoxin receptors C3a receptor and C5a receptor in nonimmune respiratory cells can prevent intrinsic lung inflammation and tissue damage. This opens up the exciting possibility in the treatment of COVID-19.


Subject(s)
Bronchi/immunology , COVID-19/immunology , Complement Activation , Epithelial Cells/immunology , Receptor, Anaphylatoxin C5a/immunology , Respiratory Mucosa/immunology , SARS-CoV-2/immunology , Bronchi/pathology , Bronchi/virology , COVID-19/pathology , COVID-19/virology , Cell Line , Complement C3/immunology , Cytokines/immunology , Epithelial Cells/pathology , Epithelial Cells/virology , Humans , Inflammation/immunology , Inflammation/pathology , Respiratory Mucosa/pathology , Respiratory Mucosa/virology
11.
EMBO J ; 40(15): e107826, 2021 08 02.
Article in English | MEDLINE | ID: covidwho-1261483

ABSTRACT

SARS-CoV-2 infection causes broad-spectrum immunopathological disease, exacerbated by inflammatory co-morbidities. A better understanding of mechanisms underpinning virus-associated inflammation is required to develop effective therapeutics. Here, we discover that SARS-CoV-2 replicates rapidly in lung epithelial cells despite triggering a robust innate immune response through the activation of cytoplasmic RNA sensors RIG-I and MDA5. The inflammatory mediators produced during epithelial cell infection can stimulate primary human macrophages to enhance cytokine production and drive cellular activation. Critically, this can be limited by abrogating RNA sensing or by inhibiting downstream signalling pathways. SARS-CoV-2 further exacerbates the local inflammatory environment when macrophages or epithelial cells are primed with exogenous inflammatory stimuli. We propose that RNA sensing of SARS-CoV-2 in lung epithelium is a key driver of inflammation, the extent of which is influenced by the inflammatory state of the local environment, and that specific inhibition of innate immune pathways may beneficially mitigate inflammation-associated COVID-19.


Subject(s)
COVID-19/immunology , DEAD Box Protein 58/immunology , Epithelial Cells/immunology , Interferon-Induced Helicase, IFIH1/immunology , Macrophages/immunology , RNA, Viral/immunology , Receptors, Immunologic/immunology , SARS-CoV-2 , COVID-19/genetics , COVID-19/virology , Cell Line , Cytokines/genetics , Cytokines/immunology , Epithelial Cells/virology , Host-Pathogen Interactions , Humans , Immunity, Innate , Inflammation/genetics , Inflammation/immunology , Inflammation/virology , Janus Kinases/immunology , Lung/cytology , Lung/immunology , Lung/virology , Macrophage Activation , NF-kappa B/immunology , Respiratory Mucosa/cytology , Respiratory Mucosa/immunology , Respiratory Mucosa/virology , SARS-CoV-2/genetics , SARS-CoV-2/physiology , STAT Transcription Factors/immunology , Virus Replication
12.
mBio ; 12(2)2021 04 27.
Article in English | MEDLINE | ID: covidwho-1206005

ABSTRACT

SARS-CoV-2 infection causing the COVID-19 pandemic calls for immediate interventions to avoid viral transmission, disease progression, and subsequent excessive inflammation and tissue destruction. Primary normal human bronchial epithelial cells are among the first targets of SARS-CoV-2 infection. Here, we show that ColdZyme medical device mouth spray efficiently protected against virus entry, excessive inflammation, and tissue damage. Applying ColdZyme to fully differentiated, polarized human epithelium cultured at an air-liquid interphase (ALI) completely blocked binding of SARS-CoV-2 and increased local complement activation mediated by the virus as well as productive infection of the tissue model. While SARS-CoV-2 infection resulted in exaggerated intracellular complement activation immediately following infection and a drop in transepithelial resistance, these parameters were bypassed by single pretreatment of the tissues with ColdZyme mouth spray. Crucially, our study highlights the importance of testing already evaluated and safe drugs such as ColdZyme mouth spray for maintaining epithelial integrity and hindering SARS-CoV-2 entry within standardized three-dimensional (3D) in vitro models mimicking the in vivo human airway epithelium.IMPORTANCE Although our understanding of COVID-19 continuously progresses, essential questions regarding prophylaxis and treatment remain open. A hallmark of severe SARS-CoV-2 infection is a hitherto-undescribed mechanism leading to excessive inflammation and tissue destruction associated with enhanced pathogenicity and mortality. To tackle the problem at the source, transfer of SARS-CoV-2, subsequent binding, infection, and inflammatory responses have to be avoided. In this study, we used fully differentiated, mucus-producing, and ciliated human airway epithelial cultures to test the efficacy of ColdZyme medical device mouth spray in terms of protection from SARS-CoV-2 infection. Importantly, we found that pretreatment of the in vitro airway cultures using ColdZyme mouth spray resulted in significantly shielding the epithelial integrity, hindering virus binding and infection, and blocking excessive intrinsic complement activation within the airway cultures. Our in vitro data suggest that ColdZyme mouth spray may have an impact in prevention of COVID-19.


Subject(s)
Antiviral Agents/pharmacology , Respiratory Mucosa/drug effects , SARS-CoV-2/drug effects , Bronchi/cytology , COVID-19/prevention & control , COVID-19/virology , Complement C3/immunology , Epithelial Cells , Humans , Immunity, Innate/drug effects , Nasal Mucosa/drug effects , Nasal Mucosa/immunology , Nasal Mucosa/virology , Oral Sprays , Respiratory Mucosa/immunology , Respiratory Mucosa/virology , SARS-CoV-2/physiology , Virus Attachment/drug effects
13.
Front Immunol ; 12: 653969, 2021.
Article in English | MEDLINE | ID: covidwho-1190317

ABSTRACT

Under normal physiological conditions, the lung remains an oxygen rich environment. However, prominent regions of hypoxia are a common feature of infected and inflamed tissues and many chronic inflammatory respiratory diseases are associated with mucosal and systemic hypoxia. The airway epithelium represents a key interface with the external environment and is the first line of defense against potentially harmful agents including respiratory pathogens. The protective arsenal of the airway epithelium is provided in the form of physical barriers, and the production of an array of antimicrobial host defense molecules, proinflammatory cytokines and chemokines, in response to activation by receptors. Dysregulation of the airway epithelial innate immune response is associated with a compromised immunity and chronic inflammation of the lung. An increasing body of evidence indicates a distinct role for hypoxia in the dysfunction of the airway epithelium and in the responses of both innate immunity and of respiratory pathogens. Here we review the current evidence around the role of tissue hypoxia in modulating the host-pathogen interaction at the airway epithelium. Furthermore, we highlight the work needed to delineate the role of tissue hypoxia in the pathophysiology of chronic inflammatory lung diseases such as asthma, cystic fibrosis, and chronic obstructive pulmonary disease in addition to novel respiratory diseases such as COVID-19. Elucidating the molecular mechanisms underlying the epithelial-pathogen interactions in the setting of hypoxia will enable better understanding of persistent infections and complex disease processes in chronic inflammatory lung diseases and may aid the identification of novel therapeutic targets and strategies.


Subject(s)
COVID-19/immunology , Host-Pathogen Interactions/immunology , Hypoxia/immunology , Lung/immunology , Respiratory Mucosa/immunology , SARS-CoV-2/physiology , COVID-19/pathology , Humans , Hypoxia/pathology , Lung/blood supply , Lung/pathology , Respiratory Mucosa/blood supply , Respiratory Mucosa/pathology
14.
Am J Respir Crit Care Med ; 204(4): 421-430, 2021 08 15.
Article in English | MEDLINE | ID: covidwho-1180997

ABSTRACT

Rationale: Mechanical ventilation is a mainstay of intensive care but contributes to the mortality of patients through ventilator-induced lung injury. eCypA (extracellular CypA [cyclophilin A]) is an emerging inflammatory mediator and metalloproteinase inducer, and the gene responsible for its expression has recently been linked to coronavirus disease (COVID-19). Objectives: To explore the involvement of eCypA in the pathophysiology of ventilator-induced lung injury. Methods: Mice were ventilated with a low or high Vt for up to 3 hours, with or without blockade of eCypA signaling, and lung injury and inflammation were evaluated. Human primary alveolar epithelial cells were exposed to in vitro stretching to explore the cellular source of eCypA, and CypA concentrations were measured in BAL fluid from patients with acute respiratory distress syndrome to evaluate the clinical relevance. Measurements and Main Results: High-Vt ventilation in mice provoked a rapid increase in soluble CypA concentration in the alveolar space but not in plasma. In vivo ventilation and in vitro stretching experiments indicated the alveolar epithelium as the likely major source. In vivo blockade of eCypA signaling substantially attenuated physiological dysfunction, macrophage activation, and MMPs (matrix metalloproteinases). Finally, we found that patients with acute respiratory distress syndrome showed markedly elevated concentrations of eCypA within BAL fluid. Conclusions: CypA is upregulated within the lungs of injuriously ventilated mice (and critically ill patients), where it plays a significant role in lung injury. eCypA represents an exciting novel target for pharmacological intervention.


Subject(s)
Anti-Inflammatory Agents/immunology , Cyclophilin A/immunology , Inflammation/immunology , Respiration, Artificial/adverse effects , Respiratory Distress Syndrome/immunology , Respiratory Mucosa/immunology , Ventilator-Induced Lung Injury/immunology , Ventilator-Induced Lung Injury/physiopathology , Animals , COVID-19/genetics , COVID-19/physiopathology , Cells, Cultured/drug effects , Cyclophilin A/pharmacology , Humans , Inflammation/physiopathology , Male , Mice , Models, Animal , Respiratory Distress Syndrome/physiopathology , SARS-CoV-2 , Ventilator-Induced Lung Injury/genetics
15.
Scand J Immunol ; 93(6): e13024, 2021 Jun.
Article in English | MEDLINE | ID: covidwho-1091011

ABSTRACT

Early airway responses to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection are of interest since they could decide whether coronavirus disease-19 (COVID-19) will proceed to life-threatening pulmonary disease stages. Here I discuss endothelial-epithelial co-operative in vivo responses producing first-line, humoral innate defence opportunities in human airways. The pseudostratified epithelium of human nasal and tracheobronchial airways are prime sites of exposure and infection by SARS-CoV-2. Just beneath the epithelium runs a profuse systemic microcirculation. Its post-capillary venules respond conspicuously to mucosal challenges with autacoids, allergens and microbes, and to mere loss of epithelium. By active venular endothelial gap formation, followed by transient yielding of epithelial junctions, non-sieved plasma macromolecules move from the microcirculation to the mucosal surface. Hence, plasma-derived protein cascade systems and antimicrobial peptides would have opportunity to operate jointly on an unperturbed mucosal lining. Similarly, a plasma-derived, dynamic gel protects sites of epithelial sloughing-regeneration. Precision for this indiscriminate humoral molecular response lies in restricted location and well-regulated duration of plasma exudation. Importantly, the endothelial responsiveness of the airway microcirculation differs distinctly from the relatively non-responsive, low-pressure pulmonary microcirculation that non-specifically, almost irreversibly, leaks plasma in life-threatening COVID-19. Observations in humans of infections with rhinovirus, coronavirus 229E, and influenza A and B support a general but individually variable early occurrence of plasma exudation in human infected nasal and tracheobronchial airways. Investigations are warranted to elucidate roles of host- and drug-induced airway plasma exudation in restriction of viral infection and, specifically, whether it contributes to variable disease responses following exposure to SARS-CoV-2.


Subject(s)
COVID-19/immunology , COVID-19/virology , Host-Pathogen Interactions/immunology , Immunity, Humoral , Respiratory Mucosa/immunology , Respiratory Mucosa/virology , SARS-CoV-2/immunology , Antibodies, Viral/blood , Antibodies, Viral/immunology , Biomarkers/blood , Blood Proteins , COVID-19/diagnosis , COVID-19/metabolism , Capillary Permeability/immunology , Complement Activation/immunology , Complement System Proteins/immunology , Complement System Proteins/metabolism , Exudates and Transudates , Humans , Immunity, Innate , Immunoglobulin M/blood , Immunoglobulin M/immunology , Microvessels/immunology , Microvessels/metabolism , Respiratory Mucosa/metabolism
16.
Eur J Clin Invest ; 50(7): e13259, 2020 Jul.
Article in English | MEDLINE | ID: covidwho-1084256

ABSTRACT

BACKGROUND: The clinical features of COVID-19 pneumonia range from a mild illness to patients with a very severe illness with acute hypoxemic respiratory failure requiring ventilation and Intensive Care Unit admission. AIMS: To provide a brief overview of the existing evidence for such differences in host response and outcome, and generate hypotheses for divergent patterns and avenues for future research, by highlighting similarities and differences in histopathological appearance between COVID-19 and influenza as well as previous coronavirus outbreaks, and by discussing predisposition through genetics and underlying disease. MATERIALS AND METHOD: We assessed the available early literature for histopathological patterns of COVID-19 pneumonia and underlying risk factors. RESULT: The histopathological spectrum of COVID-19 pneumonia includes variable patterns of epithelial damage, vascular complications, fibrosis and inflammation. Risk factors for a fatal disease include older age, respiratory disease, diabetes mellitus, obesity and hypertension. DISCUSSION: While some risk factors and their potential role in COVID-19 pneumonia are increasingly recognized, little is known about the mechanisms behind episodes of sudden deterioration or the infrequent idiosyncratic clinical demise in otherwise healthy and young subjects. CONCLUSION: The answer to many of the remaining questions regarding COVID-19 pneumonia pathogenesis may in time be provided by genotyping as well careful clinical, serological, radiological and histopathological phenotyping.


Subject(s)
Coronavirus Infections/pathology , Edema/pathology , Inflammation/pathology , Pneumonia, Viral/pathology , Respiratory Mucosa/pathology , Thrombosis/pathology , Age Factors , Angiotensin-Converting Enzyme 2 , Betacoronavirus , COVID-19 , Coronavirus Infections/epidemiology , Coronavirus Infections/genetics , Coronavirus Infections/immunology , Cytokine Release Syndrome/immunology , Diabetes Mellitus/epidemiology , Fibrosis , Genetic Predisposition to Disease , HLA Antigens/genetics , Humans , Hypertension/epidemiology , Inflammation/immunology , Influenza, Human/pathology , Obesity/epidemiology , Pandemics , Peptidyl-Dipeptidase A/genetics , Pneumonia, Viral/epidemiology , Pneumonia, Viral/genetics , Pneumonia, Viral/immunology , Polymorphism, Genetic , Respiratory Mucosa/immunology , Respiratory System/pathology , Risk Factors , SARS-CoV-2 , Serine Endopeptidases/genetics , Severe Acute Respiratory Syndrome/pathology
17.
PLoS Pathog ; 17(1): e1009153, 2021 01.
Article in English | MEDLINE | ID: covidwho-1006381

ABSTRACT

Neuropilin-1 (NRP-1), a member of a family of signaling proteins, was shown to serve as an entry factor and potentiate SARS Coronavirus 2 (SARS-CoV-2) infectivity in vitro. This cell surface receptor with its disseminated expression is important in angiogenesis, tumor progression, viral entry, axonal guidance, and immune function. NRP-1 is implicated in several aspects of a SARS-CoV-2 infection including possible spread through the olfactory bulb and into the central nervous system and increased NRP-1 RNA expression in lungs of severe Coronavirus Disease 2019 (COVID-19). Up-regulation of NRP-1 protein in diabetic kidney cells hint at its importance in a population at risk of severe COVID-19. Involvement of NRP-1 in immune function is compelling, given the role of an exaggerated immune response in disease severity and deaths due to COVID-19. NRP-1 has been suggested to be an immune checkpoint of T cell memory. It is unknown whether involvement and up-regulation of NRP-1 in COVID-19 may translate into disease outcome and long-term consequences, including possible immune dysfunction. It is prudent to further research NRP-1 and its possibility of serving as a therapeutic target in SARS-CoV-2 infections. We anticipate that widespread expression, abundance in the respiratory and olfactory epithelium, and the functionalities of NRP-1 factor into the multiple systemic effects of COVID-19 and challenges we face in management of disease and potential long-term sequelae.


Subject(s)
COVID-19/immunology , Neuropilin-1/immunology , SARS-CoV-2/immunology , Virus Internalization , COVID-19/pathology , Diabetic Nephropathies/immunology , Diabetic Nephropathies/pathology , Diabetic Nephropathies/virology , Humans , Immunologic Memory , Olfactory Bulb/immunology , Olfactory Bulb/pathology , Olfactory Bulb/virology , Respiratory Mucosa/immunology , Respiratory Mucosa/pathology , Respiratory Mucosa/virology , T-Lymphocytes/immunology , T-Lymphocytes/pathology
18.
PLoS Pathog ; 16(12): e1009128, 2020 12.
Article in English | MEDLINE | ID: covidwho-992722

ABSTRACT

Cytokine storm is suggested as one of the major pathological characteristics of SARS-CoV-2 infection, although the mechanism for initiation of a hyper-inflammatory response, and multi-organ damage from viral infection is poorly understood. In this virus-cell interaction study, we observed that SARS-CoV-2 infection or viral spike protein expression alone inhibited angiotensin converting enzyme-2 (ACE2) receptor protein expression. The spike protein promoted an angiotensin II type 1 receptor (AT1) mediated signaling cascade, induced the transcriptional regulatory molecules NF-κB and AP-1/c-Fos via MAPK activation, and increased IL-6 release. SARS-CoV-2 infected patient sera contained elevated levels of IL-6 and soluble IL-6R. Up-regulated AT1 receptor signaling also influenced the release of extracellular soluble IL-6R by the induction of the ADAM-17 protease. Use of the AT1 receptor antagonist, Candesartan cilexetil, resulted in down-regulation of IL-6/soluble IL-6R release in spike expressing cells. Phosphorylation of STAT3 at the Tyr705 residue plays an important role as a transcriptional inducer for SOCS3 and MCP-1 expression. Further study indicated that inhibition of STAT3 Tyr705 phosphorylation in SARS-CoV-2 infected and viral spike protein expressing epithelial cells did not induce SOCS3 and MCP-1 expression. Introduction of culture supernatant from SARS-CoV-2 spike expressing cells on a model human liver endothelial Cell line (TMNK-1), where transmembrane IL-6R is poorly expressed, resulted in the induction of STAT3 Tyr705 phosphorylation as well as MCP-1 expression. In conclusion, our results indicated that the presence of SARS-CoV-2 spike protein in epithelial cells promotes IL-6 trans-signaling by activation of the AT1 axis to initiate coordination of a hyper-inflammatory response.


Subject(s)
COVID-19/immunology , Interleukin-6/immunology , Receptors, Angiotensin/metabolism , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , COVID-19/metabolism , Cytokine Release Syndrome/immunology , Cytokine Release Syndrome/metabolism , Cytokine Release Syndrome/virology , Epithelial Cells/immunology , Epithelial Cells/metabolism , Epithelial Cells/virology , Humans , Interleukin-6/metabolism , Respiratory Mucosa/immunology , Respiratory Mucosa/metabolism , Respiratory Mucosa/virology , SARS-CoV-2/metabolism , Signal Transduction/physiology , Transcriptional Activation
19.
Mar Drugs ; 18(12)2020 Dec 14.
Article in English | MEDLINE | ID: covidwho-977761

ABSTRACT

The mucus layer of the nasopharynx and bronchial epithelium has a barrier function against inhaled pathogens such as the coronavirus SARS-CoV-2. We recently found that inorganic polyphosphate (polyP), a physiological, metabolic energy (ATP)-providing polymer released from blood platelets, blocks the binding of the receptor binding domain (RBD) to the cellular ACE2 receptor in vitro. PolyP is a marine natural product and is abundantly present in marine bacteria. Now, we have approached the in vivo situation by studying the effect of polyP on the human alveolar basal epithelial A549 cells in a mucus-like mucin environment. These cells express mucins as well as the ectoenzymes alkaline phosphatase (ALP) and adenylate kinase (ADK), which are involved in the extracellular production of ATP from polyP. Mucin, integrated into a collagen-based hydrogel, stimulated cell growth and attachment. The addition of polyP to the hydrogel significantly increased cell attachment and also the expression of the membrane-tethered mucin MUC1 and the secreted mucin MUC5AC. The increased synthesis of MUC1 was also confirmed by immunostaining. This morphogenetic effect of polyP was associated with a rise in extracellular ATP level. We conclude that the nontoxic and non-immunogenic polymer polyP could possibly also exert a protective effect against SARS-CoV-2-cell attachment; first, by stimulating the innate antiviral response by strengthening the mucin barrier with its antimicrobial proteins, and second, by inhibiting virus attachment to the cells, as deduced from the reduction in the strength of binding between the viral RBD and the cellular ACE2 receptor.


Subject(s)
Aquatic Organisms/metabolism , Biological Products/pharmacology , COVID-19/prevention & control , Polyphosphates/pharmacology , Respiratory Mucosa/drug effects , A549 Cells , Bacteria/metabolism , Biological Products/therapeutic use , COVID-19/virology , Humans , Immunity, Innate/drug effects , Mucin 5AC/metabolism , Mucin-1/metabolism , Polyphosphates/metabolism , Polyphosphates/therapeutic use , Respiratory Mucosa/immunology , Respiratory Mucosa/metabolism , SARS-CoV-2/immunology , SARS-CoV-2/pathogenicity , Secondary Metabolism , Virus Attachment/drug effects
20.
Nat Commun ; 11(1): 6122, 2020 11 30.
Article in English | MEDLINE | ID: covidwho-952011

ABSTRACT

Vaccine and antiviral development against SARS-CoV-2 infection or COVID-19 disease would benefit from validated small animal models. Here, we show that transgenic mice expressing human angiotensin-converting enzyme 2 (hACE2) by the human cytokeratin 18 promoter (K18 hACE2) represent a susceptible rodent model. K18 hACE2 transgenic mice succumbed to SARS-CoV-2 infection by day 6, with virus detected in lung airway epithelium and brain. K18 ACE2 transgenic mice produced a modest TH1/2/17 cytokine storm in the lung and spleen that peaked by day 2, and an extended chemokine storm that was detected in both lungs and brain. This chemokine storm was also detected in the brain at day 6. K18 hACE2 transgenic mice are, therefore, highly susceptible to SARS-CoV-2 infection and represent a suitable animal model for the study of viral pathogenesis, and for identification and characterization of vaccines (prophylactic) and antivirals (therapeutics) for SARS-CoV-2 infection and associated severe COVID-19 disease.


Subject(s)
Angiotensin-Converting Enzyme 2 , COVID-19 , Disease Models, Animal , Angiotensin-Converting Enzyme 2/genetics , Angiotensin-Converting Enzyme 2/immunology , Animals , Brain/immunology , Brain/pathology , Brain/virology , COVID-19/immunology , COVID-19/pathology , Cytokine Release Syndrome/immunology , Cytokine Release Syndrome/pathology , Disease Susceptibility , Genetic Predisposition to Disease , Keratin-18/genetics , Lung/immunology , Lung/pathology , Lung/virology , Mice , Mice, Transgenic , Mortality , Promoter Regions, Genetic/genetics , Respiratory Mucosa/immunology , Respiratory Mucosa/pathology , Respiratory Mucosa/virology , Virus Diseases/immunology , Virus Diseases/pathology
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