ABSTRACT
BACKGROUND: COVID-19 can present with lymphopenia and extraordinary complex multiorgan pathologies that can trigger long-term sequela. AIMS: Given that inflammasome products, like caspase-1, play a role in the pathophysiology of a number of co-morbid conditions, we investigated caspases across the spectrum of COVID-19 disease. MATERIALS & METHODS: We assessed transcriptional states of multiple caspases and using flow cytometry, the expression of active caspase-1 in blood cells from COVID-19 patients in acute and convalescent stages of disease. Non-COVID-19 subject presenting with various comorbid conditions served as controls. RESULTS: Single-cell RNA-seq data of immune cells from COVID-19 patients showed a distinct caspase expression pattern in T cells, neutrophils, dendritic cells, and eosinophils compared with controls. Caspase-1 was upregulated in CD4+ T-cells from hospitalized COVID-19 patients compared with unexposed controls. Post-COVID-19 patients with lingering symptoms (long-haulers) also showed upregulated caspase-1activity in CD4+ T-cells that ex vivo was attenuated with a select pan-caspase inhibitor. We observed elevated caspase-3/7levels in red blood cells from COVID-19 patients compared with controls that was reduced following caspase inhibition. DISCUSSION: Our preliminary results suggest an exuberant caspase response in COVID-19 that may facilitate immune-related pathological processes leading to severe outcomes. Further clinical correlations of caspase expression in different stages of COVID-19 will be needed. CONCLUSION: Pan-caspase inhibition could emerge as a therapeutic strategy to ameliorate or prevent severe COVID-19.
Subject(s)
COVID-19 Drug Treatment , COVID-19 , Caspase Inhibitors , CD4-Positive T-Lymphocytes , COVID-19/complications , Caspase 1 , Caspase 3 , Caspase 7 , Caspase Inhibitors/therapeutic use , Caspases/genetics , Humans , Post-Acute COVID-19 SyndromeABSTRACT
Development of antibody protection during SARS-CoV-2 infection is a pressing question for public health and for vaccine development. We developed highly sensitive SARS-CoV-2-specific antibody and neutralization assays. SARS-CoV-2 Spike protein or Nucleocapsid protein specific IgG antibodies at titers more than 1:100,000 were detectable in all PCR+ subjects (n = 115) and were absent in the negative controls. Other isotype antibodies (IgA, IgG1-4) were also detected. SARS-CoV-2 neutralization was determined in COVID-19 and convalescent plasma at up to 10,000-fold dilution, using Spike protein pseudotyped lentiviruses, which were also blocked by neutralizing antibodies (NAbs). Hospitalized patients had up to 3000-fold higher antibody and neutralization titers compared to outpatients or convalescent plasma donors. Interestingly, some COVID-19 patients also possessed NAbs against SARS-CoV Spike protein pseudovirus. Together these results demonstrate the high specificity and sensitivity of our assays, which may impact understanding the quality or duration of the antibody response during COVID-19 and in determining the effectiveness of potential vaccines.
Subject(s)
Antibodies, Neutralizing/chemistry , Antibodies, Viral/chemistry , COVID-19/diagnosis , Coronavirus Nucleocapsid Proteins/chemistry , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/chemistry , Adult , Angiotensin-Converting Enzyme 2/chemistry , Angiotensin-Converting Enzyme 2/immunology , Angiotensin-Converting Enzyme 2/metabolism , Antibodies, Neutralizing/biosynthesis , Antibodies, Viral/biosynthesis , COVID-19/immunology , COVID-19/virology , Convalescence , Coronavirus Nucleocapsid Proteins/immunology , Coronavirus Nucleocapsid Proteins/metabolism , Enzyme-Linked Immunosorbent Assay/methods , Epitopes/chemistry , Epitopes/immunology , Epitopes/metabolism , Female , Genetic Vectors/chemistry , Genetic Vectors/metabolism , Humans , Immune Sera/chemistry , Immunity, Humoral , Lentivirus/genetics , Lentivirus/immunology , Male , Middle Aged , Neutralization Tests , Phosphoproteins/chemistry , Phosphoproteins/immunology , Phosphoproteins/metabolism , Protein Binding , Receptors, Virus/chemistry , Receptors, Virus/immunology , Receptors, Virus/metabolism , SARS-CoV-2/drug effects , SARS-CoV-2/pathogenicity , Severity of Illness Index , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolism , Survival AnalysisABSTRACT
Development of antibody protection during SARS-CoV-2 infection is a pressing question for public health and for vaccine development. We developed highly sensitive SARS-CoV-2-specific antibody and neutralization assays. SARS-CoV-2 Spike protein or Nucleocapsid protein specific IgG antibodies at titers more than 1:100,000 were detectable in all PCR+ subjects (n=115) and were absent in the negative controls. Other isotype antibodies (IgA, IgG1-4) were also detected. SARS-CoV-2 neutralization was determined in COVID-19 and convalescent plasma at up to 10,000-fold dilution, using Spike protein pseudotyped lentiviruses, which were also blocked by neutralizing antibodies (NAbs). Hospitalized patients had up to 3000-fold higher antibody and neutralization titers compared to outpatients or convalescent plasma donors. Interestingly, some COVID-19 patients also possessed NAbs against SARS-CoV Spike protein pseudovirus. Together these results demonstrate the high specificity and sensitivity of our assays, which may impact understanding the quality or duration of the antibody response during COVID-19 and in determining the effectiveness of potential vaccines.
