Effects of Toll Like Receptor Agonists and SARS-Cov-2 Antigens on Interferon (IFN) Expression by Peripheral Blood CD3+ T Cells in COVID-19 Patients (preprint)

Background: Signaling by toll like receptors (TLRs) initiates important immune responses against viral infection. The role of TLRs in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections is not well elucidated. Thus, we investigated the interaction of TLRs agonists and SARS-COV-2 antigens with immune cells in vitro. Material & methods: 30 coronavirus disease 2019 (COVID-19) patients (15 severe and 15 moderate) and 10 age and sex matched control (HC) were enrolled. Peripheral blood mononuclear cells (PBMCs) were isolated and activated with TLR3, 7, 8 and 9 agonists, the spike protein (SP) of SARS-CoV-2 and the Receptor Binding Domain (RBD) unit of SP. Frequencies of CD3+IFN-β+ T cells, and CD3+IFN-g+ T cells was evaluated by flow cytometry. Interferon (IFN)-b gene expression was assessed by qRT-PCR. Results: The frequency of CD3+IFN-β+ T cells was higher in moderate and severe patients at baseline in comparison with HCs. Stimulation of PBMCs from moderate patients with SP and TLR8 agonist significantly upregulated the frequency of CD3+IFN-β+ T cells (P=0.0005 and 0.0024, respectively) when compared to non-stimulated (NS) samples. The greatest increase in CD3+IFN-b+ T cell frequency in PBMCs from severe patients was seen with TLR8 and TLR7 agonists when compared to NS (P= 0.003 and 0.0167, respectively). TLR stimulation did not significantly enhance the frequency of CD3+IFN-g+ T cells generated from PBMCs from moderate and severe patients compared with unstimulated controls. However, the frequency of CD3+IFN-ɣ+ T cells in PBMCs from moderate patients was upregulated by agonists of TLR3, 8 and 9, SP and RBD when compared with NS samples from HCs. The expression of the IFN-β gene after stimulation of CD3+T cells with the TLR8 agonist was also up-regulated in moderate than severe patients (moderate vs. severe: p=0.0006). In addition, stimulation of CD3+ T cells with SP, up-regulated the expression of IFN-β gene expression in cells from patients with moderate disease (moderate vs. severe: p=0.01). Conclusion: Stimulation of PBMCs from COVID-19 patients with a TLR8 agonist and with SP enhanced IFN-b protein and gene levels. This may potentiate immune responses against SARS-CoV-2 infection and prevent viral replication and spread.

Long-standing COVID-19 disease in immunedeficient patients; case reports and literature review (preprint)

Introduction: Patients with primary or secondary immunodeficiency are at higher risk of severe disease and death following SARS-CoV-2 infection compared with the general population. We describe here the effect of rituximab therapy in 5 patients with humoral and cellular immune deficiencies (1 patient with thymoma or Good`syndrome, 1 HIV/AIDS positive patient, 2 patients with Multiple Sclerosis (MS) and 1 patient with chronic lymphocytic leukemia (CLL). T cell responses were evaluated using the QuantiFERON SARS-CoV-2 assay following incubation with the SARS-CoV-2 Ag1, Ag2 and Ag3 viral antigens. Immunephenotyping of T cells (TCD4+, TCD8+) and B cells (CD19+ and CD20+) was determined by flow cytometry. Results: All studied immunocompromised patients showed reduced cellular immune responses (release of interferon (IFN)-g) to SARS-CoV-2 antigens than healthy controls [patients; Ag1, Ag2 and Ag3 and Nil (Median 5-95% percentile) (12 (1-95), 12 (1.5-78), 13.5 (12-95)  and 3 (1-98) U/ml)], ]controls; Ag1,Ag2 and Ag3 and Nil (Median 5-95% percentile) 24.5 (7-89), 65 (31-173), 53.5 (13-71.5) and 3 (1-14) U/ml)]. The frequency of peripheral blood B cells was also reduced in these patients compared to healthy control subjects (p=0.0282). Conclusion: T-cell dependent antibody responses require the activation of B cells by helper T cells. Reduced B cell numbers in immunocompromised patients infected with SARS-CoV-2 indicates the need for these patients to take additional precautions to prevent COVID-19 infection

Decreased Serum Levels of Angiotensin Converting Enzyme (ACE)2 and Enhanced Cytokine Levels with Severity of COVID-19: Normalisation Upon Disease Recovery (preprint)

Background:SARS-CoV-2 causes coronavirus disease 2019 (COVID-19). Circulating soluble angiotensin-converting enzyme (sACE2), the main receptor for SARS-CoV-2, together with components of the renin-angiotensin system promote infection and disease severity. Objective: In this pilot study we followed the time-course of sACE2 levels in relation to systemic cytokines in severe and moderate COVID-19 patients treated with remdesivir/dexamethasone in combination. Methods: Peripheral blood was obtained upon admission from 30 patients (12 with moderate disease and 18 with severe disease) and 14 patients with PCR-confirmed mild COVID-19. Severe and moderate patients were treated with remdesivir (200mg/first day and 100mg/day for the remaining days ) and dexamethasone (100mg/day ). 6 healthy control subjects (HC) were also enrolled. Serum interleukin (IL)-6 and IL-8 and sACE2 levels were measured by ELISA at baseline and during treatment in severe and moderate patients and at baseline in mild and HCs. Results: Baseline sACE2 levels were lower in severe (p=0.0005) and moderate (p=0.0022) patients than in patients with mild COVID-19 and in HC (p=0.0023 and p=0.0012 respectively). Serum sACE2 levels increased in patients with severe disease recovered over time compared with moderate (p=0.0021) and severe (p=0.0411) COVID-19 subjects at baseline. Systemic IL-6 and IL-8 levels were higher in all patient groups compared with HC and were not significantly affected over time or by remdesivir/dexamethasone treatment for 5 days. Conclusion: Serum sACE2 levels increase in severe COVID-19 patients as they recover over time whilst circulating cytokines are unaffected. Future studies should link these results to clinical outcomes.Funding: IMA is financially supported by the Welcome Trust (093080/Z/10/Z), the EPSRC (EP/T003189/1), and the Community Jameel Imperial College COVID-19 Excellence Fund (G26290) and by the UK MRC (MR/T010371/1). SM is supported by EU project 853850.Declaration of Interests: The authors declare that there is no conflict of interest to this article.Ethics Approval Statement: The study was approved by the institutional ethics board of the Masih Daneshvari Hospital (Ethics number SBMU.NRITLD.REC.1399.226).

Decision support system to evaluate VENTilation in the Acute Respiratory Distress Syndrome (DeVENT study) – Trial Protocol (preprint)

Background The Acute Respiratory Distress Syndrome (ARDS) occurs in response to a variety of insults, and mechanical ventilation is life-saving in this setting, but ventilator induced lung injury can also contribute to the morbidity and mortality in the condition. The Beacon Caresystem is a model-based bedside decision support system using mathematical models tuned to the individual patient’s physiology to advise on appropriate ventilator settings. Personalised approaches using individual patient description may be particularly advantageous in complex patients, including those who are difficult to mechanically ventilate and wean, in particular ARDS. Methods We will conduct a multi-centre international randomised, controlled, allocation concealed, open, pragmatic clinical trial to compare mechanical ventilation in ARDS patients following application of the Beacon Caresystem to that of standard routine care to investigate whether use of the system results in a reduction in driving pressure across all severities and phases of ARDS. Discussion Despite 20 years of clinical trial data showing significant improvements in ARDS mortality through mitigation of ventilator induced lung injury, there remains a gap in its personalised application at the bedside. Importantly, the protective effects of higher positive end-expiratory pressure (PEEP) were noted only when there were associated decreases in driving pressure. Hence, the pressures set on the ventilator should be determined by the diseased lungs’ pressure-volume relationship which is often unknown or difficult to determine. Knowledge of extent of recruitable lung could improve the ventilator driving pressure. Hence, personalised management demands the application of mechanical ventilation according to the physiological state of the diseased lung at that time. Hence, there is significant rationale for the development of point-of-care clinical decision support systems which help personalise ventilatory strategy according to the current physiology. Furthermore, the potential for the application of the Beacon Caresystem to facilitate local and remote management of large numbers of ventilated patients (as seen during this COVID-19 pandemic), could change the outcome of mechanically ventilated patients during the course of this and future pandemics. Trial registration ClinicalTrials.gov identifier ( NCT number): NCT04115709 Administrative information Note: the numbers in curly brackets in this protocol refer to SPIRIT checklist item numbers. The order of the items has been modified to group similar items (see http://www.equator-network.org/reporting-guidelines/spirit-2013-statement-defining-standard-protocol-items-for-clinical-trials/ ).

Myeloid-derived Suppressor Cells in the Blood of Iranian COVID-19 Patients (preprint)

Background: A cytokine storm and lymphopenia are reported in coronavirus disease 2019 (COVID-19). Myeloid-derived suppressive cells (MDSCs) exist in two different forms, granulocyte (G-MDSCs) and monocytic (M-MDSCs) that both suppress T-cell function. Serum IL-6 and IL-8 levels seem to correlate with the number of blood MDSCs. Objective: In the current study we aimed to find MDSCs frequency in severe COVID-19 patients from Iran and their correlations with serum IL-8 levels. Methods: : 37 severe (8 on ventilation, 29 without ventilation) and 13 moderate COVID-19 patients together with 8 healthy subjects were enrolled at the Masih Daneshvari Hospital, Tehran-Iran between 10th April 2020- 9th March 2021. Clinical and biochemical features, serum and whole blood were obtained. CD14, CD15, CD11b and HLA-DR expression on MDSCs was measured by flow cytometry. Results: : M-MDSCs (P≤0.0001) and G-MDSCs (P≤0.0001) frequency were higher in Iranian COVID-19 patients compared to healthy subjects. M-MDSC frequency was higher in non-ventilated compared to moderate COVID-19 subjects (P=0.004). IL-8 levels were higher in patients serum with COVID-19 than in normal healthy subjects (P=0.03). IL8 level was significant difference in ventilated, non-ventilated and moderate patients (P=0.005). The frequency of G-MDSCs correlated negatively with INR (r=-0.39, P=0.02). Conclusion: Serum IL-8 levels did not correlate with the number of systemic MDSCs in COVID-19 patients. The highest levels of M-MDSCs were seen in the blood of severe non-ventilated patients. MDSC frequency in blood in the current study did not predict the survival and severity of COVID-19 patients.

Myeloid-derived suppressor cells in the blood of Iranian COVID-19 patients (preprint)

Background A cytokine storm and lymphopenia are reported in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection associated with coronavirus disease 2019 (COVID-19). Myeloid-derived suppressive cells (MDSCs) exist in two different forms, granulocyte (G-MDSCs) and monocytic (M-MDSCs) that both suppress T-cell function. Serum IL-6 and IL-8 levels seem to correlate with the number of blood MDSCs. Objective To determine the frequency of MDSCs in severe COVID-19 patients from Iran and their correlations with serum IL-8 levels. Methods 37 severe (8 on ventilation, 29 without ventilation) and 13 moderate COVID-19 patients together with 8 healthy subjects were enrolled at the Masih Daneshvari Hospital, Tehran-Iran between 10th April 2020-9th March 2021. Clinical and biochemical features, serum and whole blood were obtained. CD14, CD15, CD11b and HLA-DR expression on MDSCs was measured by flow cytometry. Results M-MDSCs (P≤0.0001) and G-MDSCs (P≤0.0001) frequency were higher in Iranian COVID-19 patients compared to healthy subjects. M-MDSC frequency was higher in non-ventilated compared to moderate COVID-19 subjects (P=0.004). Serum IL-8 levels were higher in patients with COVID-19 than in normal healthy subjects (P=0.03). IL8 level was significant difference in ventilated, non-ventilated and moderate patients (P=0.005). The frequency of G-MDSCs correlated negatively with INR (r=-0.39, P=0.02). Conclusion Serum IL-8 levels did not correlate with the number of systemic MDSCs in COVID-19 patients. The highest levels of M-MDSCs were seen in the blood of severe non-ventilated patients. MDSC frequency in blood in the current study did not predict the survival and severity of COVID-19 patients.

Sputum ACE2, TMPRSS2 and FURIN gene expression in severe neutrophilic asthma (preprint)

Background: Patients with severe asthma may have a greater risk of dying from COVID-19 disease. Angiotensin converting enzyme-2 (ACE2) and the enzyme proteases, transmembrane protease serine 2 (TMPRSS2) and FURIN, are needed for viral attachment and invasion into host cells. Methods. We examined microarray mRNA expression of ACE2, TMPRSS2 and FURIN in sputum, bronchial brushing and bronchial biopsies of the European U-BIOPRED cohort. Clinical parameters and molecular phenotypes, including asthma severity, sputum inflammatory cells, lung functions, oral corticosteroid (OCS) use, and transcriptomic-associated clusters, were examined in relation to gene expression levels. Results. ACE2 levels were significantly increased in sputum of severe asthma compared to mild-moderate asthma. In multivariate analyses, sputum ACE2 levels were positively associated with OCS use and male gender. Sputum FURIN levels were significantly related to neutrophils (%) and the presence of severe asthma. In bronchial brushing samples, TMPRSS2 levels were positively associated with male gender and body mass index, whereas FURIN levels with male gender and blood neutrophils. In bronchial biopsies, TMPRSS2 levels were positively related to blood neutrophils. The neutrophilic molecular phenotype characterised by high inflammasome activation expressed significantly higher FURIN levels in sputum than the eosinophilic Type 2-high or the pauci-granulocytic oxidative phosphorylation phenotypes. Conclusion. Levels of ACE2 and FURIN may differ by clinical or molecular phenotypes of asthma. Sputum FURIN expression levels were strongly associated with neutrophilic inflammation and with inflammasome activation. This might indicate the potential for a greater morbidity and mortality outcome from SARS-CoV-2 infection in neutrophilic severe asthma.

Determinants of SARS-CoV-2 receptor gene expression in upper and lower airways (preprint)

The recent outbreak of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), has led to a worldwide pandemic. One week after initial symptoms develop, a subset of patients progresses to severe disease, with high mortality and limited treatment options. To design novel interventions aimed at preventing spread of the virus and reducing progression to severe disease, detailed knowledge of the cell types and regulating factors driving cellular entry is urgently needed. Here we assess the expression patterns in genes required for COVID-19 entry into cells and replication, and their regulation by genetic, epigenetic and environmental factors, throughout the respiratory tract using samples collected from the upper (nasal) and lower airways (bronchi). Matched samples from the upper and lower airways show a clear increased expression of these genes in the nose compared to the bronchi and parenchyma. Cellular deconvolution indicates a clear association of these genes with the proportion of secretory epithelial cells. Smoking status was found to increase the majority of COVID-19 related genes including ACE2 and TMPRSS2 but only in the lower airways, which was associated with a significant increase in the predicted proportion of goblet cells in bronchial samples of current smokers. Both acute and second hand smoke were found to increase ACE2 expression in the bronchus. Inhaled corticosteroids decrease ACE2 expression in the lower airways. No significant effect of genetics on ACE2 expression was observed, but a strong association of DNA- methylation with ACE2 and TMPRSS2- mRNA expression was identified in the bronchus.

Prime-boost protein subunit vaccines against SARS-CoV-2 are highly immunogenic in mice and macaques (preprint)

SARS-CoV-2 vaccines are advancing into human clinical trials, with emphasis on eliciting high titres of neutralising antibodies against the viral spike (S). However, the merits of broadly targeting S versus focusing antibody onto the smaller receptor binding domain (RBD) are unclear. Here we assessed prototypic S and RBD subunit vaccines in homologous or heterologous prime-boost regimens in mice and non-human primates. We find S is highly immunogenic in mice, while the comparatively poor immunogenicity of RBD was associated with limiting germinal centre and T follicular helper cell activity. Boosting S-primed mice with either S or RBD significantly augmented neutralising titres, with RBD-focussing driving moderate improvement in serum neutralisation. In contrast, both S and RBD vaccines were comparably immunogenic in macaques, eliciting serological neutralising activity that generally exceed levels in convalescent humans. These studies confirm recombinant S proteins as promising vaccine candidates and highlight multiple pathways to achieving potent serological neutralisation.

An intestinal cell type in zebrafish is the nexus for the SARS-CoV-2 receptor and the Renin-Angiotensin-Aldosterone System that contributes to COVID-19 comorbidities (preprint)

People with underlying conditions, including hypertension, obesity, and diabetes, are especially susceptible to negative outcomes after infection with the coronavirus SARS-CoV-2. These COVID-19 comorbidities are exacerbated by the Renin-Angiotensin-Aldosterone System (RAAS), which normally protects from rapidly dropping blood pressure or dehydration via the peptide Angiotensin II (Ang II) produced by the enzyme Ace. The Ace paralog Ace2 degrades Ang II, thus counteracting its chronic effects. Ace2 is also the SARS-CoV-2 receptor. Ace, the coronavirus, and COVID-19 comorbidities all regulate Ace2, but we dont yet understand how. To exploit zebrafish (Danio rerio) as a disease model to understand mechanisms regulating the RAAS and its relationship to COVID-19 comorbidities, we must first identify zebrafish orthologs and co-orthologs of human RAAS genes, and second, understand where and when these genes are expressed in specific cells in zebrafish development. To achieve these goals, we conducted genomic analyses and investigated single cell transcriptomes. Results showed that most human RAAS genes have an ortholog in zebrafish and some have two or more co-orthologs. Results further identified a specific intestinal cell type in zebrafish larvae as the site of expression for key RAAS components, including Ace, Ace2, the coronavirus co-receptor Slc6a19, and the Angiotensin-related peptide cleaving enzymes Anpep and Enpep. Results also identified specific vascular cell subtypes as expressing Ang II receptors, apelin, and apelin receptor genes. These results identify specific genes and cell types to exploit zebrafish as a disease model for understanding the mechanisms leading to COVID-19 comorbidities. SUMMARY STATEMENTGenomic analyses identify zebrafish orthologs of the Renin-Angiotensin-Aldosterone System that contribute to COVID-19 comorbidities and single-cell transcriptomics show that they act in a specialized intestinal cell type.

Structural Variants in SARS-CoV-2 Occur at Template-Switching Hotspots (preprint)

The evolutionary dynamics of SARS-CoV-2 have been carefully monitored since the COVID-19 pandemic began in December 2019, however, analysis has focused primarily on single nucleotide polymorphisms and largely ignored the role of structural variants (SVs) as well as recombination in SARS-CoV-2 evolution. Using sequences from the GISAID database, we catalogue over 100 insertions and deletions in the SARS-CoV-2 consensus sequences. We hypothesize that these indels are artifacts of imperfect homologous recombination between SARS-CoV-2 replicates, and provide four independent pieces of evidence. (1) The SVs from the GISAID consensus sequences are clustered at specific regions of the genome. (2) These regions are also enriched for 5 and 3 breakpoints in the transcription regulatory site (TRS) independent transcriptome, presumably sites of RNA-dependent RNA polymerase (RdRp) template-switching. (3) Within raw reads, these structural variant hotspots have cases of both high intra-host heterogeneity and intra-host homogeneity, suggesting that these structural variants are both consequences of de novo recombination events within a host and artifacts of previous recombination. (4) Within the RNA secondary structure, the indels occur in "arms" of the predicted folded RNA, suggesting that secondary structure may be a mechanism for TRS-independent template-switching in SARS-CoV-2 or other coronaviruses. These insights into the relationship between structural variation and recombination in SARS-CoV-2 can improve our reconstructions of the SARS-CoV-2 evolutionary history as well as our understanding of the process of RdRp template-switching in RNA viruses.

Modeling SARS-CoV-2 infection in vitro with a human intestine-on-chip device (preprint)

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus (SARS-CoV-2) has given rise to a global pandemic. The gastrointestinal symptoms of some COVID-19 patients are underestimated. There is an urgent need to develop physiologically relevant model that can accurately reflect human response to viral infection. Here, we report the creation of a biomimetic human intestine infection model on a chip system that allows to recapitulate the intestinal injury and immune response induced by SARS-CoV-2, for the first time. The microengineered intestine-on-chip device contains human intestinal epithelium (co-cultured human intestinal epithelial Caco-2 cells and mucin secreting HT-29 cells) lined in upper channel and vascular endothelium (human umbilical vein endothelial cells, HUVECs) in a parallel lower channel under fluidic flow condition, sandwiched by a porous PDMS membrane coated with extracellular matrix (ECM). At day 3 post-infection of SARS-CoV-2, the intestine epithelium showed high susceptibility to viral infection and obvious morphological changes with destruction of intestinal villus, dispersed distribution of mucus secreting cells and reduced expression of tight junction (E-cadherin), indicating the destruction of mucous layer and the integrity of intestinal barrier caused by virus. Moreover, the endothelium exhibited abnormal cell morphology with disrupted expression of adherent junction protein (VE-cadherin). Transcriptional analysis revealed the abnormal RNA and protein metabolism, as well as activated immune responses in both epithelial and endothelial cells after viral infection (e.g., up-regulated cytokine genes, TNF signaling and NF-kappa B signaling-related genes). This bioengineered in vitro model system can mirror the human relevant pathophysiology and response to viral infection at the organ level, which is not possible in existing in vitro culture systems. It may provide a promising tool to accelerate our understanding of COVID-19 and devising novel therapies.

Spike mutation D614G alters SARS-CoV-2 fitness and neutralization susceptibility (preprint)

A spike protein mutation D614G became dominant in SARS-CoV-2 during the COVID-19 pandemic. However, the mutational impact on viral spread and vaccine efficacy remains to be defined. Here we engineer the D614G mutation in the SARS-CoV-2 USA-WA1/2020 strain and characterize its effect on viral replication, pathogenesis, and antibody neutralization. The D614G mutation significantly enhances SARS-CoV-2 replication on human lung epithelial cells and primary human airway tissues, through an improved infectivity of virions with the spike receptor-binding domain in an "up" conformation for binding to ACE2 receptor. Hamsters infected with D614 or G614 variants developed similar levels of weight loss. However, the G614 virus produced higher infectious titers in the nasal washes and trachea, but not lungs, than the D614 virus. The hamster results confirm clinical evidence that the D614G mutation enhances viral loads in the upper respiratory tract of COVID-19 patients and may increases transmission. For antibody neutralization, sera from D614 virus-infected hamsters consistently exhibit higher neutralization titers against G614 virus than those against D614 virus, indicating that (i) the mutation may not reduce the ability of vaccines in clinical trials to protect against COVID-19 and (ii) therapeutic antibodies should be tested against the circulating G614 virus before clinical development. ImportanceUnderstanding the evolution of SARS-CoV-2 during the COVID-19 pandemic is essential for disease control and prevention. A spike protein mutation D614G emerged and became dominant soon after the pandemic started. By engineering the D614G mutation into an authentic wild-type SARS-CoV-2 strain, we demonstrate the importance of this mutation to (i) enhanced viral replication on human lung epithelial cells and primary human airway tissues, (ii) improved viral fitness in the upper airway of infected hamsters, and (iii) increased susceptibility to neutralization. Together with clinical findings, our work underscores the importance of this mutation in viral spread, vaccine efficacy, and antibody therapy.

Happy Hypoxia: Higher NO in red blood cells of COVID-19 patients (preprint)

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes coronavirus disease 2019 (COVID-19) has spread to almost 100 countries, infected over 10M patients and resulted in 505K deaths worldwide as of 30th June 2020. The major clinical feature of severe COVID-19 requiring ventilation is acute Respiratory Distress Syndrome (ARDS) with multi-functional failure as a result of a cytokine storm with increased serum levels of cytokines. The pathogenesis of the respiratory failure in COVID-19 is yet unknown, but diffuse alveolar damage with interstitial thickening leading to compromised gas exchange is a plausible mechanism. Hypoxia has been seen in the COVID-19 patients however, patients present with a distinct phenotype. Intracellular levels of NO playing important role in the vasodilation of small vessels.Objectives: To elucidate the intracellular levels of NO inside of RBCs in COVID-19 patients compared with that of healthy control subjects.Methods: We recruited 14 COVID-19 infected cases who had pulmonary involvement of their disease, 4 non-COVID-19 healthy controls (without pulmonary involvement and were not hypoxic) and 2 hypoxic non-COVID-19 patients subjects who presented at the Masih Daneshvari Hospital of Tehran, Iran between March-May 2020. Whole blood samples were harvested from patients and intracellular levels of NO in 1 million red blood cells (RBC) was measured by DAF staining using flow cytometry (FACS Calibour, BD, CA, USA).Results: The Mean florescent of intensity for NO was significantly enhanced in COVID-19 patients compared with healthy control subjects (P≤0.05). As a further control for whether hypoxia induced this higher intracellular NO, we evaluated the levels of NO inside RBC of hypoxic patients. No significant differences in NO levels were seen between the hypoxic and non-hypoxic control group.Conclusions: This pilot study demonstrates increased levels of intracellular NO in RBCs from COVID-19 patients. Future studies should examine whether intracellular NO would be increased in large number of COVID-19 patients for usage of possible NO therapy in severe patients. 

Airway expression of SARS-CoV-2 receptor, ACE2, and proteases, TMPRSS2 and furin, in severe asthma (preprint)

Background. Patients with severe asthma may have a greater risk of dying from COVID-19 disease caused by SARS-CoV-2 virus. Angiotensin converting enzyme 2 (ACE2) receptor and enzyme proteases, transmembrane protease, serine 2 (TMPRSS2) and furin are needed for the attachment and invasion of the virus into host cells. We determined whether their expression in the airways of severe asthma patients is increased. Method. We examined the microarray mRNA expression of ACE2, TMPRSS2 and furin in the sputum, bronchial brush and bronchial biopsies of participants in the European U-BIOPRED cohort. Results. ACE2 and furin sputum gene expression was significantly increased in severe non-smoking asthma compared to mild-moderate asthma and healthy volunteers. By contrast, TMPRSS2 expression in bronchial biopsy and bronchial brushings was increased in severe smoking and ex-smoking asthmatics, and so was furin expression in bronchial brushings. Several clinical parameters including male gender, oral steroid use and nasal polyps were positively associated with ACE2, TMPRSS2 and furin expression levels. There was a higher expression of ACE2 and furin in the sputum neutrophilic molecular phenotype with inflammasome activation compared to the eosinophilic Type2-high or paucigranulocytic phenotypes. The enrichment score of the IL-13-Type2 gene signature was positively correlated with ACE2, TMPRSS2 and furin levels. Conclusion. These key determinants of virus entry into the lungs may contribute to the poorer outcomes from COVID-19 disease in patients with severe asthma.