COVID-19-induced “acute respiratory distress syndrome” (ARDS) is associated with prolonged respiratory failure and high mortality, but the mechanistic basis of lung injury remains incompletely ...understood. Here, we analyze pulmonary immune responses and lung pathology in two cohorts of patients with COVID-19 ARDS using functional single-cell genomics, immunohistology, and electron microscopy. We describe an accumulation of CD163-expressing monocyte-derived macrophages that acquired a profibrotic transcriptional phenotype during COVID-19 ARDS. Gene set enrichment and computational data integration revealed a significant similarity between COVID-19-associated macrophages and profibrotic macrophage populations identified in idiopathic pulmonary fibrosis. COVID-19 ARDS was associated with clinical, radiographic, histopathological, and ultrastructural hallmarks of pulmonary fibrosis. Exposure of human monocytes to SARS-CoV-2, but not influenza A virus or viral RNA analogs, was sufficient to induce a similar profibrotic phenotype in vitro. In conclusion, we demonstrate that SARS-CoV-2 triggers profibrotic macrophage responses and pronounced fibroproliferative ARDS.
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•Monocyte-derived macrophages accumulate in the lung in COVID-19 ARDS•Macrophages in COVID-19 express genes associated with profibrotic functions•Patients with severe COVID-19 ARDS display hallmarks of pulmonary fibrosis•SARS-CoV-2 induces a profibrotic transcriptome and proteome profile in macrophages
SARS-CoV-2 infection, but not influenza A, triggers immunological and pathological changes in the lung that are hallmarks of pulmonary fibrosis. A subset of CD163+ macrophages are found to drive this fibroproliferative acute respiratory distress.
A review of mechanisms of apoptosis induction in influenza virus‐infected cells, and the impact of apoptotic signaling on viral propagation, immune responses, and tissue injury.
Programmed cell death ...is a crucial cellular response frequently observed in IV‐infected tissue. This article reviews the current knowledge on the molecular virus–host interactions that induce apoptosis pathways in an IV‐infected cell and the functional implications of these cellular signaling events on viral propagation at distinct steps during the viral replication cycle. Furthermore, it summarizes the role of IV‐induced apoptosis pathways in equilibrating the hostˈs antiviral immune response between effective viral clearance and development of severe apoptotic lung injury.
Abstract Inhibition of influenza A virus infection by multivalent sialic acid inhibitors preventing viral hemagglutinin binding to host cells of the respiratory tract is a promising strategy. ...However, optimal geometry and optimal ligand presentation on multivalent scaffolds for efficient inhibition both in vitro and in vivo application are still unclear. Here, by comparing linear and dendritic polyglycerol sialosides (LPGSA and dPGSA) we identified architectural requirements and optimal ligand densities for an efficient multivalent inhibitor of influenza virus A/X31/1 (H3N2). Due to its large volume, the LPGSA at optimal ligand density sterically shielded the virus significantly better than the dendritic analog. A statistical mechanics model rationalizes the relevance of ligand density, morphology, and the size of multivalent scaffolds for the potential to inhibit virus-cell binding. Optimized LPGSA inhibited virus infection at IC50 in the low nanomolar nanoparticle concentration range and also showed potent antiviral activity against two avian influenza strains A/Mallard/439/2004 (H3N2) and A/turkey/Italy/472/1999 (H7N1) post infection. I n vivo application of inhibitors clearly confirmed the higher inhibition potential of linear multivalent scaffolds to prevent infection. The optimized LPGSA did not show any acute toxicity, and was much more potent than the neuraminidase inhibitor oseltamivir carboxylate in vivo . Combined application of the LPGSA and oseltamivir carboxylate revealed a synergistic inhibitory effect and successfully prevented influenza virus infection in mice.
The current model is that the influenza virus polymerase (FluPol) binds either to host RNA polymerase II (RNAP II) or to the acidic nuclear phosphoprotein 32 (ANP32), which drives its conformation ...and activity towards transcription or replication of the viral genome, respectively. Here, we provide evidence that the FluPol-RNAP II binding interface, beyond its well-acknowledged function in cap-snatching during transcription initiation, has also a pivotal role in replication of the viral genome. Using a combination of cell-based and in vitro approaches, we show that the RNAP II C-terminal-domain, jointly with ANP32, enhances FluPol replication activity. We observe successive conformational changes to switch from a transcriptase to a replicase conformation in the presence of the bound RNPAII C-terminal domain and propose a model in which the host RNAP II is the anchor for transcription and replication of the viral genome. Our data open new perspectives on the spatial coupling of viral transcription and replication and the coordinated balance between these two activities.
During the initial COVID-19 response, Germany's Federal Government implemented several nonpharmaceutical interventions (NPIs) that were instrumental in suppressing early exponential spread of ...SARS-CoV-2. NPI effect on the transmission of other respiratory viruses has not been examined at the national level thus far.
Upper respiratory tract specimens from 3580 patients with acute respiratory infection (ARI), collected within the nationwide German ARI Sentinel, underwent RT-PCR diagnostics for multiple respiratory viruses. The observation period (weeks 1-38 of 2020) included the time before, during and after a far-reaching contact ban. Detection rates for different viruses were compared to 2017-2019 sentinel data (15350 samples; week 1-38, 11823 samples).
The March 2020 contact ban, which was followed by a mask mandate, was associated with an unprecedented and sustained decline of multiple respiratory viruses. Among these, rhinovirus was the single agent that resurged to levels equalling those of previous years. Rhinovirus rebound was first observed in children, after schools and daycares had reopened. By contrast, other nonenveloped viruses (i.e. gastroenteritis viruses reported at the national level) suppressed after the shutdown did not rebound.
Contact restrictions with a subsequent mask mandate in spring may substantially reduce respiratory virus circulation. This reduction appears sustained for most viruses, indicating that the activity of influenza and other respiratory viruses during the subsequent winter season might be low,whereas rhinovirus resurgence, potentially driven by transmission in educational institutions in a setting of waning population immunity, might signal predominance of rhinovirus-related ARIs.
Robert Koch-Institute and German Ministry of Health.
Pandemic influenza A virus (IAV) outbreaks occur when strains from animal reservoirs acquire the ability to infect and spread among humans. The molecular basis of this species barrier is incompletely ...understood. Here we combine metabolic pulse labeling and quantitative proteomics to monitor protein synthesis upon infection of human cells with a human- and a bird-adapted IAV strain and observe striking differences in viral protein synthesis. Most importantly, the matrix protein M1 is inefficiently produced by the bird-adapted strain. We show that impaired production of M1 from bird-adapted strains is caused by increased splicing of the M segment RNA to alternative isoforms. Strain-specific M segment splicing is controlled by the 3' splice site and functionally important for permissive infection. In silico and biochemical evidence shows that avian-adapted M segments have evolved different conserved RNA structure features than human-adapted sequences. Thus, we identify M segment RNA splicing as a viral host range determinant.
•Techno-economic evaluation of a large-scale NG-H2 separation plant•Process simulation and optimization for a 4-bed 8-step PSA system•A general methodology for simulation-based optimization of ...PSA-based processes•A simulation-based optimization framework using Aspen Adsorption V11 and MATLAB
Green H2 plays an important role in the global energy transition. To improve its supply chain economics, the already existing gas grids can be an interim solution for its storage and transportation infrastructure. Injecting H2 into the gas networks seems straightforward from a process design standpoint. However, the extraction, at the other end of the supply chain, poses challenges, and its feasibility from the techno-economic viewpoint is crucial and can support the further development of such programs. This article presents a rigorous techno-economic and optimization model for this process developed in Aspen Adsorption V11 and MATLAB. This holistic model uses the cyclic steady-state approach of Aspen Adsorption V11, which avoids the redundant computations for achieving the steady-state performance in the dynamic simulation approach and allows for the development of a novel simulation-based optimization framework. The proposed optimization model can be used in other pressure swing adsorption applications to improve the rigorousness of the optimal solution and computational time. The results show that H2 extraction from a distribution grid with 30 mol% H2 and 70 mol% CH4 at 12 bar operating pressure costs $0.8064/kg-H2 and $0.9012/kg-H2 for product purities of 99.00 mol% and 99.97 mol%, respectively. Additionally, this study explores the impact of N2 and CO2 presence in natural gas on H2 separation costs. For natural gas containing CH4: CO2: N2 with a molar ratio of 95:2:3 mixed with 30 mol% H2, the separation cost of the 99.00 mol% pure H2 increases by 11.6% to $0.8998/kg-H2; however, based on the simulation, the purity of 99.97 mol% due to the presence of N2 is not technically achievable.
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Influenza viruses (IV) cause pneumonia in humans with progression to lung failure and fatal outcome. Dysregulated release of cytokines including type I interferons (IFNs) has been attributed a ...crucial role in immune-mediated pulmonary injury during severe IV infection. Using ex vivo and in vivo IV infection models, we demonstrate that alveolar macrophage (AM)-expressed IFN-β significantly contributes to IV-induced alveolar epithelial cell (AEC) injury by autocrine induction of the pro-apoptotic factor TNF-related apoptosis-inducing ligand (TRAIL). Of note, TRAIL was highly upregulated in and released from AM of patients with pandemic H1N1 IV-induced acute lung injury. Elucidating the cell-specific underlying signalling pathways revealed that IV infection induced IFN-β release in AM in a protein kinase R- (PKR-) and NF-κB-dependent way. Bone marrow chimeric mice lacking these signalling mediators in resident and lung-recruited AM and mice subjected to alveolar neutralization of IFN-β and TRAIL displayed reduced alveolar epithelial cell apoptosis and attenuated lung injury during severe IV pneumonia. Together, we demonstrate that macrophage-released type I IFNs, apart from their well-known anti-viral properties, contribute to IV-induced AEC damage and lung injury by autocrine induction of the pro-apoptotic factor TRAIL. Our data suggest that therapeutic targeting of the macrophage IFN-β-TRAIL axis might represent a promising strategy to attenuate IV-induced acute lung injury.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) utilises the angiotensin-converting enzyme 2 (ACE2) transmembrane peptidase as cellular entry receptor. However, whether SARS-CoV-2 in the ...alveolar compartment is strictly ACE2-dependent and to what extent virus-induced tissue damage and/or direct immune activation determines early pathogenesis is still elusive.
Spectral microscopy, single-cell/-nucleus RNA sequencing or ACE2 "gain-of-function" experiments were applied to infected human lung explants and adult stem cell derived human lung organoids to correlate ACE2 and related host factors with SARS-CoV-2 tropism, propagation, virulence and immune activation compared to SARS-CoV, influenza and Middle East respiratory syndrome coronavirus (MERS-CoV). Coronavirus disease 2019 (COVID-19) autopsy material was used to validate
results.
We provide evidence that alveolar ACE2 expression must be considered scarce, thereby limiting SARS-CoV-2 propagation and virus-induced tissue damage in the human alveolus. Instead,
infected human lungs and COVID-19 autopsy samples showed that alveolar macrophages were frequently positive for SARS-CoV-2. Single-cell/-nucleus transcriptomics further revealed nonproductive virus uptake and a related inflammatory and anti-viral activation, especially in "inflammatory alveolar macrophages", comparable to those induced by SARS-CoV and MERS-CoV, but different from NL63 or influenza virus infection.
Collectively, our findings indicate that severe lung injury in COVID-19 probably results from a macrophage-triggered immune activation rather than direct viral damage of the alveolar compartment.
Influenza A viruses (IAV) can cause lung injury and acute respiratory distress syndrome (ARDS), which is characterized by accumulation of excessive fluid (edema) in the alveolar airspaces and leads ...to hypoxemia and death if not corrected. Clearance of excess edema fluid is driven mostly by the alveolar epithelial Na,K-ATPase and is crucial for survival of patients with ARDS. We therefore investigated whether IAV infection alters Na,K-ATPase expression and function in alveolar epithelial cells (AECs) and the ability of the lung to clear edema. IAV infection reduced Na,K-ATPase in the plasma membrane of human and murine AECs and in distal lung epithelium of infected mice. Moreover, induced Na,K-ATPase improved alveolar fluid clearance (AFC) in IAV-infected mice. We identified a paracrine cell communication network between infected and noninfected AECs and alveolar macrophages that leads to decreased alveolar epithelial Na,K-ATPase function and plasma membrane abundance and inhibition of AFC. We determined that the IAV-induced reduction of Na,K-ATPase is mediated by a host signaling pathway that involves epithelial type I IFN and an IFN-dependent elevation of macrophage TNF-related apoptosis-inducing ligand (TRAIL). Our data reveal that interruption of this cellular crosstalk improves edema resolution, which is of biologic and clinical importance to patients with IAV-induced lung injury.
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