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1.
Front Immunol ; 12: 765330, 2021.
Article in English | MEDLINE | ID: covidwho-1518489

ABSTRACT

Aims: Although the exact factors promoting disease progression in COVID-19 are not fully elucidated, unregulated activation of the complement system (CS) seems to play a crucial role in the pathogenesis of acute lung injury (ALI) induced by SARS-CoV-2. In particular, the lectin pathway (LP) has been implicated in previous autopsy studies. The primary purpose of our study is to investigate the role of the CS in hospitalized COVID-19 patients with varying degrees of disease severity. Methods: In a single-center prospective observational study, 154 hospitalized patients with PCR-confirmed SARS-CoV-2 infection were included. Serum samples on admission to the COVID-19 ward were collected for analysis of CS pathway activities and concentrations of LP proteins [mannose-binding lectin (MBL) and ficolin-3 (FCN-3)] & C1 esterase inhibitor (C1IHN). The primary outcome was mechanical ventilation or in-hospital death. Results: The patients were predominately male and had multiple comorbidities. ICU admission was required in 16% of the patients and death (3%) or mechanical ventilation occurred in 23 patients (15%). There was no significant difference in LP activity, MBL and FCN-3 concentrations according to different peak disease severities. The median alternative pathway (AP) activity was significantly lower (65%, IQR 50-94) in patients with death/invasive ventilation compared to patients without (87%, IQR 68-102, p=0.026). An optimal threshold of <65.5% for AP activity was derived from a ROC curve resulting in increased odds for death or mechanical ventilation (OR 4,93; 95% CI 1.70-14.33, p=0.003) even after adjustment for confounding factors. Classical pathway (CP) activity was slightly lower in patients with more severe disease (median 101% for death/mechanical ventilation vs 109%, p=0.014). C1INH concentration correlated positively with length of stay, inflammatory markers and disease severity on admission but not during follow-up. Conclusion: Our results point to an overactivated AP in critically ill COVID-19 patients in vivo leading to complement consumption and consequently to a significantly reduced AP activity in vitro. The LP does not seem to play a role in the progression to severe COVID-19. Apart from its acute phase reaction the significance of C1INH in COVID-19 requires further studies.


Subject(s)
COVID-19/immunology , Complement System Proteins/immunology , SARS-CoV-2 , Adult , Aged , COVID-19/blood , COVID-19/mortality , COVID-19/therapy , Complement C1 Inhibitor Protein/immunology , Critical Illness , Female , Hospital Mortality , Hospitalization , Humans , Lectins/immunology , Male , Middle Aged , Prospective Studies , Respiration, Artificial , Severity of Illness Index
2.
Nature ; 598(7880): 342-347, 2021 10.
Article in English | MEDLINE | ID: covidwho-1379317

ABSTRACT

SARS-CoV-2 infection-which involves both cell attachment and membrane fusion-relies on the angiotensin-converting enzyme 2 (ACE2) receptor, which is paradoxically found at low levels in the respiratory tract1-3, suggesting that there may be additional mechanisms facilitating infection. Here we show that C-type lectin receptors, DC-SIGN, L-SIGN and the sialic acid-binding immunoglobulin-like lectin 1 (SIGLEC1) function as attachment receptors by enhancing ACE2-mediated infection and modulating the neutralizing activity of different classes of spike-specific antibodies. Antibodies to the amino-terminal domain or to the conserved site at the base of the receptor-binding domain, while poorly neutralizing infection of ACE2-overexpressing cells, effectively block lectin-facilitated infection. Conversely, antibodies to the receptor binding motif, while potently neutralizing infection of ACE2-overexpressing cells, poorly neutralize infection of cells expressing DC-SIGN or L-SIGN and trigger fusogenic rearrangement of the spike, promoting cell-to-cell fusion. Collectively, these findings identify a lectin-dependent pathway that enhances ACE2-dependent infection by SARS-CoV-2 and reveal distinct mechanisms of neutralization by different classes of spike-specific antibodies.


Subject(s)
Antibodies, Neutralizing/immunology , Lectins/metabolism , SARS-CoV-2/metabolism , SARS-CoV-2/pathogenicity , Angiotensin-Converting Enzyme 2/metabolism , Animals , Cell Adhesion Molecules/metabolism , Cell Fusion , Cell Line , Cricetinae , Female , Humans , Lectins/immunology , Lectins, C-Type/metabolism , Membrane Fusion , Receptors, Cell Surface/metabolism , SARS-CoV-2/immunology , Sialic Acid Binding Ig-like Lectin 1/metabolism , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolism
3.
JCI Insight ; 6(13)2021 06 18.
Article in English | MEDLINE | ID: covidwho-1346128

ABSTRACT

We explored the potential link between chronic inflammatory arthritis and COVID-19 pathogenic and resolving macrophage pathways and their role in COVID-19 pathogenesis. We found that bronchoalveolar lavage fluid (BALF) macrophage clusters FCN1+ and FCN1+SPP1+ predominant in severe COVID-19 were transcriptionally related to synovial tissue macrophage (STM) clusters CD48hiS100A12+ and CD48+SPP1+ that drive rheumatoid arthritis (RA) synovitis. BALF macrophage cluster FABP4+ predominant in healthy lung was transcriptionally related to STM cluster TREM2+ that governs resolution of synovitis in RA remission. Plasma concentrations of SPP1 and S100A12 (key products of macrophage clusters shared with active RA) were high in severe COVID-19 and predicted the need for Intensive Care Unit transfer, and they remained high in the post-COVID-19 stage. High plasma levels of SPP1 were unique to severe COVID-19 when compared with other causes of severe pneumonia, and IHC localized SPP1+ macrophages in the alveoli of COVID-19 lung. Investigation into SPP1 mechanisms of action revealed that it drives proinflammatory activation of CD14+ monocytes and development of PD-L1+ neutrophils, both hallmarks of severe COVID-19. In summary, COVID-19 pneumonitis appears driven by similar pathogenic myeloid cell pathways as those in RA, and their mediators such as SPP1 might be an upstream activator of the aberrant innate response in severe COVID-19 and predictive of disease trajectory including post-COVID-19 pathology.


Subject(s)
Arthritis, Rheumatoid/immunology , COVID-19/immunology , Monocytes/immunology , Neutrophils/immunology , Osteopontin/immunology , Arthritis, Rheumatoid/metabolism , B7-H1 Antigen/immunology , Bronchoalveolar Lavage Fluid/immunology , CD48 Antigen/immunology , COVID-19/chemically induced , COVID-19/metabolism , Fatty Acid-Binding Proteins/immunology , Humans , Lectins/immunology , Lipopolysaccharide Receptors/immunology , Lipopolysaccharide Receptors/metabolism , Lung/diagnostic imaging , Lung/immunology , Lung/metabolism , Lung/pathology , Macrophages/immunology , Macrophages/metabolism , Membrane Glycoproteins/immunology , Monocytes/metabolism , Neutrophils/metabolism , Osteopontin/blood , Receptor Protein-Tyrosine Kinases/metabolism , Receptors, Immunologic/immunology , S100A12 Protein/immunology , S100A12 Protein/metabolism , Synovial Membrane/immunology , Tomography, X-Ray Computed
4.
Front Immunol ; 12: 671052, 2021.
Article in English | MEDLINE | ID: covidwho-1231338

ABSTRACT

We do not understand why non-white ethnicity and chronic kidney disease increase susceptibility to COVID-19. The lectin pathway of complement activation is a key contributor to innate immunity and inflammation. Concentrations of plasma lectin pathway proteins influence pathway activity and vary with ethnicity. We measured circulating lectin proteins in a multi-ethnic cohort of chronic kidney disease patients with and without COVID19 infection to determine if lectin pathway activation was contributing to COVID19 severity. We measured 11 lectin proteins in serial samples from a cohort of 33 patients with chronic kidney impairment and COVID19. Controls were single plasma samples from 32 patients on dialysis and 32 healthy individuals. We demonstrated multiple associations between recognition molecules and associated proteases of the lectin pathway and COVID-19, including COVID-19 severity. Some of these associations were unique to patients of Asian and White ethnicity. Our novel findings demonstrate that COVID19 infection alters the concentration of plasma lectin proteins and some of these changes were linked to ethnicity. This suggests a role for the lectin pathway in the host response to COVID-19 and suggest that variability within this pathway may contribute to ethnicity-associated differences in susceptibility to severe COVID-19.


Subject(s)
COVID-19/blood , Complement Pathway, Mannose-Binding Lectin , Lectins/blood , Renal Insufficiency, Chronic/blood , SARS-CoV-2/metabolism , Adult , Aged , Aged, 80 and over , COVID-19/ethnology , COVID-19/immunology , COVID-19/pathology , Female , Humans , Lectins/immunology , Male , Middle Aged , Renal Insufficiency, Chronic/ethnology , Renal Insufficiency, Chronic/immunology , Renal Insufficiency, Chronic/pathology , SARS-CoV-2/immunology
5.
Front Immunol ; 12: 650331, 2021.
Article in English | MEDLINE | ID: covidwho-1156125

ABSTRACT

Coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 infection represents a global health crisis. Immune cell activation via pattern recognition receptors has been implicated as a driver of the hyperinflammatory response seen in COVID-19. However, our understanding of the specific immune responses to SARS-CoV-2 remains limited. Mast cells (MCs) and eosinophils are innate immune cells that play pathogenic roles in many inflammatory responses. Here we report MC-derived proteases and eosinophil-associated mediators are elevated in COVID-19 patient sera and lung tissues. Stimulation of viral-sensing toll-like receptors in vitro and administration of synthetic viral RNA in vivo induced features of hyperinflammation, including cytokine elevation, immune cell airway infiltration, and MC-protease production-effects suppressed by an anti-Siglec-8 monoclonal antibody which selectively inhibits MCs and depletes eosinophils. Similarly, anti-Siglec-8 treatment reduced disease severity and airway inflammation in a respiratory viral infection model. These results suggest that MC and eosinophil activation are associated with COVID-19 inflammation and anti-Siglec-8 antibodies are a potential therapeutic approach for attenuating excessive inflammation during viral infections.


Subject(s)
Antigens, CD/immunology , Antigens, Differentiation, B-Lymphocyte/immunology , COVID-19/immunology , Eosinophils/immunology , Lectins/immunology , Mast Cells/immunology , Respiratory Syncytial Virus Infections/immunology , Respiratory Syncytial Viruses/immunology , SARS-CoV-2/immunology , Toll-Like Receptors/immunology , Animals , Antibodies, Monoclonal/pharmacology , Antigens, CD/genetics , Antigens, CD/metabolism , Antigens, Differentiation, B-Lymphocyte/genetics , Antigens, Differentiation, B-Lymphocyte/metabolism , COVID-19/metabolism , COVID-19/prevention & control , COVID-19/virology , Case-Control Studies , Cytokines/metabolism , Disease Models, Animal , Eosinophils/drug effects , Eosinophils/metabolism , Eosinophils/virology , Host-Pathogen Interactions , Humans , Lectins/antagonists & inhibitors , Lectins/genetics , Lectins/metabolism , Mast Cells/drug effects , Mast Cells/metabolism , Mast Cells/virology , Mice, Transgenic , Peptide Hydrolases/metabolism , Respiratory Syncytial Virus Infections/metabolism , Respiratory Syncytial Virus Infections/prevention & control , Respiratory Syncytial Virus Infections/virology , Toll-Like Receptors/metabolism
6.
J Biol Chem ; 296: 100375, 2021.
Article in English | MEDLINE | ID: covidwho-1062444

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged during the last months of 2019, spreading throughout the world as a highly transmissible infectious illness designated as COVID-19. Vaccines have now appeared, but the challenges in producing sufficient material and distributing them around the world means that effective treatments to limit infection and improve recovery are still urgently needed. This review focuses on the relevance of different glycobiological molecules that could potentially serve as or inspire therapeutic tools during SARS-CoV-2 infection. As such, we highlight the glycobiology of the SARS-CoV-2 infection process, where glycans on viral proteins and on host glycosaminoglycans have critical roles in efficient infection. We also take notice of the glycan-binding proteins involved in the infective capacity of virus and in human defense. In addition, we critically evaluate the glycobiological contribution of candidate drugs for COVID-19 therapy such as glycans for vaccines, anti-glycan antibodies, recombinant lectins, lectin inhibitors, glycosidase inhibitors, polysaccharides, and numerous glycosides, emphasizing some opportunities to repurpose FDA-approved drugs. For the next-generation drugs suggested here, biotechnological engineering of new probes to block the SARS-CoV-2 infection might be based on the essential glycobiological insight on glycosyltransferases, glycans, glycan-binding proteins, and glycosidases related to this pathology.


Subject(s)
Antiviral Agents/therapeutic use , COVID-19/prevention & control , Drug Repositioning , Glycoside Hydrolase Inhibitors/therapeutic use , Glycosyltransferases/antagonists & inhibitors , Viral Proteins/antagonists & inhibitors , Antibodies, Neutralizing/therapeutic use , Antiviral Agents/chemistry , COVID-19/epidemiology , COVID-19/immunology , COVID-19/virology , Drug Design , Drug Discovery , Gene Expression , Glycomics/methods , Glycosaminoglycans/chemistry , Glycosaminoglycans/immunology , Glycosaminoglycans/metabolism , Glycosyltransferases/chemistry , Glycosyltransferases/genetics , Glycosyltransferases/immunology , Host-Pathogen Interactions/drug effects , Host-Pathogen Interactions/genetics , Host-Pathogen Interactions/immunology , Humans , Lectins/chemistry , Lectins/immunology , Lectins/metabolism , Polysaccharides/chemistry , Polysaccharides/immunology , Polysaccharides/metabolism , SARS-CoV-2/chemistry , SARS-CoV-2/drug effects , SARS-CoV-2/genetics , SARS-CoV-2/immunology , Signal Transduction , Viral Proteins/chemistry , Viral Proteins/genetics , Viral Proteins/immunology
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