D-dimer and CoV-2 spike-immune complexes contribute to the production of PGE2 and proinflammatory cytokines in monocytes

Association of COVID-19 with acute and post-acute risk of multiple different complications and mortality in patients infected with omicron variant stratified by initial disease severity: a cohort study in Hong Kong

BACKGROUND

Few studies have attempted to use clinical and laboratory parameters to stratify COVID-19 patients with severe versus non-severe initial disease and evaluate age-specific differences in developing multiple different COVID-19-associated disease outcomes.

METHODS

A retrospective cohort included patients from the electronic health database of Hong Kong Hospital Authority between 1 January 2022 and 15 August 2022 until 15 November 2022. The cohort was divided into three cohorts by age (≤ 40, 41-64, and ≥ 65 years old). Each age cohort was stratified into four groups: (1) COVID-19 critically exposed group (ICU admission, mechanical ventilation support, CRP > 80 mg/L, or D-dimer > 2 g/mL), (2) severely exposed group (CRP 30-80 mg/L, D-dimer 0.5-2 g/mL, or CT value < 20), (3) mildly-moderately exposed group (COVID-19 positive-tested but not fulfilling the criteria for the aforementioned critically and severely exposed groups), and (4) unexposed group (without COVID-19). The characteristics between groups were adjusted with propensity score-based marginal mean weighting through stratification. Cox regression was conducted to determine the association of COVID-19 disease severity with disease outcomes and mortality in the acute and post-acute phase (< 30 and ≥ 30 days from COVID-19 infection) in each age group.

RESULTS

A total of 286,114, 320,304 and 194,227 patients with mild-moderate COVID-19 infection; 18,419, 23,678 and 31,505 patients with severe COVID-19 infection; 1,168, 2,261 and 10,178 patients with critical COVID-19 infection, and 1,143,510, 1,369,365 and 1,012,177 uninfected people were identified in aged ≤ 40, 40-64, and ≥ 65 groups, respectively. Compared to the unexposed group, a general trend tending towards an increase in risks of multiple different disease outcomes as COVID-19 disease severity increases, with advancing age, was identified in both the acute and post-acute phases. Notably, the mildly-moderately exposed group were associated with either insignificant risks (aged ≤ 40) or the lowest risks (aged > 40) for the disease outcomes in the acute phase of infection (e.g., mortality risk HR (aged ≤ 40): 1.0 (95%CI: 0.5,2.0), HR (aged 41-64): 2.1 (95%CI: 1.8, 2.6), HR (aged > 65): 4.8 (95%CI: 4.6, 5.1)); while in the post-acute phase, these risks were largely insignificant in those aged < 65, remaining significant only in the elderly (age ≥ 65) (e.g., mortality risk HR (aged ≤ 40): 0.8 (95%CI: (0.5, 1.0)), HR (aged 41-64): 1.1 (95%CI: 1.0,1.2), HR (aged > 65): 1.5 (95%CI: 1.5,1.6)). Fully vaccinated patients were associated with lower risks of disease outcomes than those receiving less than two doses of vaccination.

CONCLUSIONS

The risk of multiple different disease outcomes in both acute and post-acute phases increased significantly with the increasing severity of acute COVID-19 illness, specifically among the elderly. Moreover, future studies could improve by risk-stratifying patients based on universally accepted thresholds for clinical parameters, particularly biomarkers, using biological evidence from immunological studies.

Association of TLR8 Variants in Sex-Based Clinical Differences in Patients with COVID-19

The host immune response might confer differential vulnerability to SARS-CoV-2 infection. The Toll-like receptor 8 (TLR8), could participated for severe COVID-19 outcomes. To investigated the relationship of TLR8 rs3764879-C/G, rs3764880-A/G, and rs3761624-A/G with COVID-19 outcomes and with biochemical parameters. A cross-sectional study of 830 laboratory-confirmed COVID-19 patients was performed, and classified into mild, severe, critical, and deceased outcomes. The TLR8 rs3764879-C/G, rs3764880-A/G, and rs3761624-A/G polymorphisms were genotyped. A logistic regression analysis was performed to determinate the association with COVID-19. A stratified analysis was by alleles was done with clinical and metabolic markets. In all outcomes, men presented the highest ferritin levels compared to women (P < 0.001). LDH levels were significantly different between sex in mild (P = 0.003), severe (P < 0.001) and deceased (P = 0.01) COVID-19 outcomes. The GGG haplotype showed an Odds Ratio of 1.55 (Interval Confidence 95% 1.05-2.32; P = 0.03) in men. Among patients with severe outcome, we observed that the carriers of the GGG haplotype had lower Ferritin, C-reactive protein and LDH levels than the CAA carriers (P < 0.01). After further stratified by sex, these associations were also seen in the male patients, except for D-dimer. Interestingly, among men patients, we could observe associations between TLR8 haplotypes and Ferritin (P < 0.001), D-dimer (P = 0.04), C-reactive protein, and Lactate dehydrogenase in mild (P = 0.04) group. Our results suggest that even though TLR8 haplotypes show a significant association with COVID-19 outcomes, they are associated with clinical markers in COVID-19 severity.

Pyrogenic and inflammatory mediators are produced by polarized M1 and M2 macrophages activated with D-dimer and SARS-CoV-2 spike immune complexes

Lung macrophages are the first line of defense against invading respiratory pathogens including SARS-CoV-2, yet activation of macrophage in the lungs can lead to hyperinflammatory immune response seen in severe COVID-19. Here we used human M1 and M2 polarized macrophages as a surrogate model of inflammatory and regulatory macrophages and explored whether immune complexes (IC) containing spike-specific IgG can trigger aberrant cytokine responses in macrophages in the lungs and associated lymph nodes. We show that IC of SARS-CoV-2 recombinant S protein coated with spike-specific monoclonal antibody induced production of Prostaglandin E2 (PGE2) in non-polarized (M0) and in M1 and M2-type polarized human macrophages only in the presence of D-dimer (DD), a fibrinogen degradation product, associated with coagulopathy in COVID-19. Importantly, an increase in PGE2 was also observed in macrophages activated with DD and IC of SARS-CoV-2 pseudovirions coated with plasma from hospitalized COVID-19 patients but not from healthy subjects. Overall, the levels of PGE2 in macrophages activated with DD and IC were as follows: M1≫M2>M0 and correlated with the levels of spike binding antibodies and not with neutralizing antibody titers. All three macrophage subsets produced similar levels of IL-6 following activation with DD+IC, however TNFα, IL-1β, and IL-10 cytokines were produced by M2 macrophages only. Our study suggests that high titers of spike or virion containing IC in the presence of coagulation byproducts (DD) can promote inflammatory response in macrophages in the lungs and associated lymph nodes and contribute to severe COVID-19.

Variant-dependent oxidative and cytokine responses of human neutrophils to SARS-CoV-2 spike protein and anti-spike IgG1 antibodies

Introduction

Severe forms of COVID-19, the disease caused by SARS-CoV-2, are characterized by acute respiratory distress syndrome, robust lung inflammation and death in some patients. Strong evidence has been accumulating that polymorphonuclear neutrophilic granulocytes (PMN) play an important role in the pathophysiology of severe COVID-19. SARS-CoV-2 directly induces in vitro PMN activation, mainly the release of neutrophil extracellular traps (NETs). However, the viral components inducing this PMN response remain unclear.

Methods

In this work human PMN responses were assessed in vitro in response to the spike (S) protein of two different SARS-CoV-2 variants, anti-S IgG1 antibodies or immune complexes formed by them. Production of reactive oxygen species (ROS) was measured by Diogenes-based chemiluminescence. Release of myeloperoxidase (MPO) was assessed by ELISA while secretion of a list of cytokines and growth factors was determined by high-performance multiplex cytokine assay.

Results and discussion

We show that the SARS-CoV-2 Omicron variant S protein and anti-spike IgG1, either alone or together, stimulate ROS production in human PMNs. We also observed that the SARS-CoV-2 Wuhan S protein and anti-S IgG1 antibody together trigger MPO release from PMNs. Based on the relevance of SARS-CoV-2 and influenza co-infections, we have also investigated the impact of influenza virus infection on the previous PMN responses to S proteins or anti-S antibodies. We did not detect any significant effect of influenza co-infection on ROS generation in PMNs. Our data also show that PMN stimulation by S proteins induced the release of different chemokines, growth factors, regulatory and proinflammatory cytokines. Overall, our findings show that the SARS-CoV-2 S protein, an anti-spike IgG1 antibody or their immune complex, promote oxidative responses of PMNs in a variant-dependent manner, contributing to a better understanding of the role of PMN responses during SARS-CoV-2 infection.

An Interplay between Oxidative Stress (Lactate Dehydrogenase) and Inflammation (Anisocytosis) Mediates COVID-19 Severity Defined by Routine Clinical Markers

Viral infections activate the innate immune response and the secretion of inflammatory cytokines. They also alter oxidative stress markers, which potentially can have an involvement in the pathogenesis of the disease. The aim of this research was to study the role of the oxidative stress process assessed through lactate dehydrogenase (LDH) on the severity of COVID-19 measured by oxygen saturation (SaO₂) and the putative interaction with inflammation. The investigation enrolled 1808 patients (mean age of 68 and 60% male) with COVID-19 from the HM Hospitals database. To explore interactions, a regression model and mediation analyses were performed. The patients with lower SaO₂ presented lymphopenia and higher values of neutrophils-to-lymphocytes ratio and on the anisocytosis coefficient. The regression model showed an interaction between LDH and anisocytosis, suggesting that high levels of LDH (>544 U/L) and an anisocytosis coefficient higher than 10% can impact SaO₂ in COVID-19 patients. Moreover, analysis revealed that LDH mediated 41% (p value = 0.001) of the effect of anisocytosis on SaO₂ in this cohort. This investigation revealed that the oxidative stress marker LDH and the interaction with anisocytosis have an important role in the severity of COVID-19 infection and should be considered for the management and treatment of the oxidative phenomena concerning this within a precision medicine strategy.

Pharmacological Activities of Fingerroot Extract and Its Phytoconstituents Against SARS-CoV-2 Infection in Golden Syrian Hamsters

Background

The outbreak of COVID-19 has led to the suffering of people around the world, with an inaccessibility of specific and effective medication. Fingerroot extract, which showed in vitro anti-SARS-CoV-2 activity, could alleviate the deficiency of antivirals and reduce the burden of health systems.

Aim of Study

In this study, we conducted an experiment in SARS-CoV-2-infected hamsters to determine the efficacy of fingerroot extract in vivo.

Materials and Methods

The infected hamsters were orally administered with vehicle control, fingerroot extract 300 or 1000 mg/kg, or favipiravir 1000 mg/kg at 48 h post-infection for 7 consecutive days. The hamsters (n = 12 each group) were sacrificed at day 2, 4 and 8 post-infection to collect the plasma and lung tissues for analyses of viral output, lung histology and lung concentration of panduratin A.

Results

All animals in treatment groups reported no death, while one hamster in the control group died on day 3 post-infection. All treatments significantly reduced lung pathophysiology and inflammatory mediators, PGE₂ and IL-6, compared to the control group. High levels of panduratin A were found in both the plasma and lung of infected animals.

Conclusion

Fingerroot extract was shown to be a potential of reducing lung inflammation and cytokines in hamsters. Further studies of the full pharmacokinetics and toxicity are required before entering into clinical development.

Discovery of host-directed modulators of virus infection by probing the SARS-CoV-2-host protein-protein interaction network

The ongoing coronavirus disease 2019 (COVID-19) pandemic has highlighted the need to better understand virus-host interactions. We developed a network-based method that expands the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)-host protein interaction network and identifies host targets that modulate viral infection. To disrupt the SARS-CoV-2 interactome, we systematically probed for potent compounds that selectively target the identified host proteins with high expression in cells relevant to COVID-19. We experimentally tested seven chemical inhibitors of the identified host proteins for modulation of SARS-CoV-2 infection in human cells that express ACE2 and TMPRSS2. Inhibition of the epigenetic regulators bromodomain-containing protein 4 (BRD4) and histone deacetylase 2 (HDAC2), along with ubiquitin-specific peptidase (USP10), enhanced SARS-CoV-2 infection. Such proviral effect was observed upon treatment with compounds JQ1, vorinostat, romidepsin and spautin-1, when measured by cytopathic effect and validated by viral RNA assays, suggesting that the host proteins HDAC2, BRD4 and USP10 have antiviral functions. We observed marked differences in antiviral effects across cell lines, which may have consequences for identification of selective modulators of viral infection or potential antiviral therapeutics. While network-based approaches enable systematic identification of host targets and selective compounds that may modulate the SARS-CoV-2 interactome, further developments are warranted to increase their accuracy and cell-context specificity.