Titers of antibodies the receptor-binding domain (RBD) of ancestral SARS-CoV-2 are predictive for levels of neutralizing antibodies to multiple variants (preprint)

Diagnostic assays currently used to monitor the efficacy of COVID-19 vaccines measure levels of antibodies to the receptor-binding domain of ancestral SARS-CoV-2 (RBDwt). However, the predictive value for protection against new variants of concern (VOCs) has not been firmly established. Here, we used bead-based arrays and flow cytometry to measure binding of antibodies to spike proteins and receptor-binding domains (RBDs) from VOCs in 12,000 sera. Effects of sera on RBD-ACE2 interactions were measured as a proxy for neutralizing antibodies. The samples were obtained from healthy individuals or patients on immunosuppressive therapy who had received two to four doses of COVID-19 vaccines and from COVID-19 convalescents. The results show that anti-RBDwt titers correlate with the levels of binding- and neutralizing antibodies against the Alpha, Beta, Gamma, Delta, Epsilon and Omicron variants. The benefit of multiplexed analysis lies in the ability to measure a wide range of anti-RBD titers using a single dilution of serum for each assay. The reactivity patterns also yield an internal reference for neutralizing activity and binding antibody units per milliliter (BAU/ml). Results obtained with sera from vaccinated healthy individuals and patients confirmed and extended results from previous studies on time-dependent waning of antibody levels and effects of immunosuppressive agents. We conclude that anti-RBDwt titers correlate with levels of neutralizing antibodies against VOCs and propose that our method may be implemented to enhance the precision and throughput of immunomonitoring.

Multiplexed measurement of binding- and neutralizing antibodies to SARS-CoV-2 variants in 12.000 post-vaccine sera (preprint)

Diagnostic assays currently used to monitor the efficacy of COVID-19 vaccines measure levels of antibodies to the receptor-binding domain of ancestral SARS-CoV-2 (RBDwt). However, the predictive value for protection against new variants of concern (VOCs) has not been firmly established. Here, we used bead-based arrays and flow cytometry to measure binding of antibodies to spike proteins and receptor-binding domains (RBDs) from VOCs in 12,000 sera. Effects of sera on RBD-ACE2 interactions were measured as a proxy for neutralizing antibodies. The samples were obtained from healthy individuals or patients on immunosuppressive therapy who had received two to four doses of COVID-19 vaccines and from COVID-19 convalescents. The results show that anti-RBDwt titers correlate with the levels of binding- and neutralizing antibodies against the Alpha, Beta, Gamma, Delta, Epsilon and Omicron variants. The benefit of multiplexed analysis lies in the ability to measure a wide range of anti-RBD titers using a single dilution of serum for each assay. The reactivity patterns also yield an internal reference for neutralizing activity and binding antibody units per milliliter (BAU/ml). Results obtained with sera from vaccinated healthy individuals and patients confirmed and extended results from previous studies on time-dependent waning of antibody levels and effects of immunosuppressive agents. We conclude that anti-RBDwt titers correlate with levels of neutralizing antibodies against VOCs and propose that our method may be implemented to enhance the precision and throughput of immunomonitoring.

Breakthrough infections with the omicron and delta variants of SARS-CoV-2 result in similar re-activation of vaccine-induced immunity (preprint)

Background: The Omicron variant of SARS-CoV-2 is now overtaking the Delta variant in many countries. Results showing that sera from double vaccinated individuals have minimal neutralizing activity against Omicron may indicate that the higher rate of transmission is due to evasion from vaccine-induced immunity. However, there is little information about activation of recall responses to Omicron in vaccinated individuals. Methods: We measured inflammatory mediators, antibodies to the SARS-CoV-2 spike and nucleocapsid proteins, and spike peptide-induced release of interferon gamma in whole blood in 51 vaccinated individuals infected with Omicron, in 14 infected with Delta, and in 18 healthy controls. The median time points for the first and second samples were 7 and 14 days after symptom onset, respectively. Findings: Infection with Omicron or Delta led to a rapid and similar increase in antibodies to the SARS-CoV-2 spike and nucleocapsid proteins and spike peptide-induced interferon gamma in whole blood. Both the Omicron and the Delta infected patients had a mild and transient increase in inflammatory parameters. Interpretation: The results suggest that vaccine-induced immunological memory yields similar coverage for the Omicron and Delta variants.

Superinfections in critically ill COVID-19 patients - an association with Dexamethasone? (preprint)

BacgroundSuper-infections in COVID-19 patients with acute respiratory distress syndrome (ARDS) on mechanical ventilation were initially reported to be rare. Little is known of their incidence after dexamethasone was introduced as standard care. We aimed to determine the incidence and characteristics of superinfections in mechanically ventilated COVID-19 patients during the course of the COVID-19 pandemic, and explore the possible impact of the introduction of dexamethasone as standard therapy. MethodsIn this national, multi-center, observational, retrospective study we included patients ≥ 18 years admitted from March 1 st 2020 to January 31 st 2021 with polymerase chain reaction (PCR)-confirmed SARSCoV-2 infection treated with invasive mechanical ventilation. Data was collected from electronic health records. Patient characteristics, clinical findings, microbiology, length of stay and 90-day survival were examined with backwards stepwise multiple regression. Results155 patients (115 men, mean age 62 years, range 26-84 years) were included. 73 patients (47%) had a total of 101 superinfections where pneumonia dominated (70%). Superinfections were more commonly observed in patients receiving dexamethasone (67% vs 30%, p<0.0001), and in patients with pre-existing autoimmune disease (18% vs 5%, p<0.01). Invasive fungal infections were reported exclusively in dexamethasone-treated patients [9/72 (13%) vs 0/83 (0%), p<0.0001]. There was no difference in 90-day survival between patients with and patients without superinfections (64% versus 73%, p=0.238). In multiple regression analysis, superinfection was associated with dexamethasone use [OR 5.35 (2.62–11.35), p<0.001], pre-existing autoimmune disease [OR 4.90 (1.50–19.4), p=0.008] and higher lymphocyte count at the time of admission [OR 2.31 (1.23–4.86), p=0.009]. ConclusionIn critically ill COVID-19 patients receiving invasive ventilation, introduction of dexamethasone as standard of care was strongly and independently associated with superinfections. A focus on this complication is warranted when studying alternative anti-inflammatory therapy.

Gut microbiota alterations in patients with persistent respiratory dysfunction three months after severe COVID-19 (preprint)

ObjectiveAlthough COVID-19 is primarily a respiratory infection, mounting evidence suggests that the GI tract is involved in the disease, with gut barrier dysfunction and gut microbiota alterations being related to disease severity. Whether these alterations persist and could be related to long-term respiratory dysfunction is unknown. DesignFrom the NOR-Solidarity trial (n=181), plasma was collected during hospital admission and after three months, and analyzed for markers of gut barrier dysfunction and inflammation. At the three-month follow-up, pulmonary function was assessed by measuring diffusing capacity of the lungs for carbon monoxide (DLCO), and rectal swabs for gut microbiota analyses were collected (n= 97) and analysed by sequencing of the 16S rRNA gene. ResultsGut microbiota diversity was reduced in COVID-19 patients with persistent respiratory dysfunction, defined as DLCO below lower limit of normal three months after hospitalization. These patients also had an altered global gut microbiota composition, with reduced abundance of Erysipelotrichaceae UCG-003 and increased abundance of Flavonifractor and Veillonella, the latter potentially being linked to fibrosis. During hospitalization, increased plasma levels of lipopolysaccharide-binding protein (LBP) were strongly associated with respiratory failure, defined as pO2/fiO2-(P/F-ratio)<26.6 kPa. LBP levels remained elevated during and after hospitalization, and was associated with low-grade inflammation and persistent respiratory dysfunction after three months. ConclusionPersistent respiratory dysfunction after COVID-19 is associated with reduced biodiversity and gut microbiota alterations, along with persistently elevated LBP levels. Our results point to a potential gut-lung axis that should be further investigated in relation to long-term pulmonary dysfunction and long COVID. Summary boxO_ST_ABSWhat is already known about this subject?C_ST_ABSO_LIMounting evidence suggests that the gastrointestinal tract is involved in the pathogenesis of COVID-19, with the putative SARS-CoV-2 receptor ACE 2 ubiquitously expressed in the gut. C_LIO_LIIn severe COVID-19, the gut-blood barrier is compromised, and leakage of microbial products, such as lipopolysaccharides (LPS), could affect the hosts response to COVID-19 infection. C_LIO_LICOVID-19 patients exhibit an altered gut microbiota composition, which has been related to disease severity. However, it is currently not known whether dysbiosis or gut barrier dysfunction persist long-term after hospitalization, or whether microbiota-related mechanisms could be related to persistent pulmonary dysfunction. C_LI What are the new findings?O_LICOVID-19 patients with persistent respiratory dysfunction after three months had a lower microbial diversity and an altered gut microbiota composition at the same time point. C_LIO_LIThe microbiota alterations included reduced abundance of Erysipelotrichaceae UCG-003 and increased abundance of Veillonella and Flavonifractor. C_LIO_LIDuring hospitalization, increased plasma levels of LBP were strongly associated with respiratory failure. C_LIO_LILBP levels remained elevated during and after hospitalization, and associated significantly with persistent respiratory dysfunction at three-month follow-up. C_LI How might it impact on clinical practice in the foreseeable future?Our findings point to a potential gut-lung axis in relation not only to respiratory failure during hospitalization, but also to long-term COVID-19 morbidity. Further studies on gut microbiota composition and gut barrier dysfunction as potential treatment targets and/or disease severity biomarkers in relation to long-term pulmonary dysfunction and long COVID are warranted.

Rejuveinix Mitigates Sepsis-Associated Oxidative Stress in the Brain of Mice: Clinical Impact Potential in COVID-19 and Nervous System Disorders (preprint)

Here, we demonstrate that our anti-sepsis and COVID-19 drug candidate Rejuveinix (RJX) substantially improves the survival outcome in the LPS-GalN animal model of sepsis and multi-organ failure. One hundred (100) percent (%) of untreated control mice remained alive throughout the experiment. By comparison, 100% of LPS-GalN injected mice died at a median of 4.6 hours. In contrast to the invariably fatal treatment outcome of vehicle-treated control mice, 40% of mice treated with RJX (n=25) remained alive with a 2.4-fold longer median time survival time of 10.9 hours (Log-rank X2=20.60, P<0.0001). Notably, RJX increased the tissue levels of antioxidant enzymes SOD, CAT, and GSH-Px, and reduced oxidative stress in the brain. These findings demonstrate the clinical impact potential of RJX as a neuroprotective COVID-19 and sepsis drug candidate.

Hydroxyzine inhibits SARS-CoV-2 Spike protein binding to ACE2 in a qualitative in vitro assay (preprint)

COVID-19 currently represents a major public health problem. Multiple efforts are being performed to control this disease. Vaccinations are already in progress. However, no effective treatments have been found so far. The disease is caused by the SARS-CoV-2 coronavirus that through the Spike protein interacts with its cell surface receptor ACE2 to enter into the host cells. Therefore, compounds able to block this interaction may help to stop disease progression. In this study, we have analyzed the effect of compounds reported to interact and modify the activity of ACE2 on the binding of the Spike protein. Among the compounds tested, we found that hydroxyzine could inhibit the binding of the receptor-binding domain of Spike protein to ACE2 in a qualitative in vitro assay. This finding supports the reported clinical data showing the benefits of hydroxyzine on COVID-19 patients, raising the need for further investigation into its effectiveness in the treatment of COVID-19 given its well-characterized medical properties and affordable cost.

Interferon alpha-based combinations suppress SARS-CoV-2 infection in vitro and in vivo (preprint)

There is an urgent need for new antivirals with powerful therapeutic potential and tolerable side effects. In the present study, we found that recombinant human interferon-alpha (IFNa) triggers intrinsic and extrinsic cellular antiviral responses, as well as reduces replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in vitro. Although IFNa alone was insufficient to completely abolish SARS-CoV-2 replication, combinations of IFNa with remdesivir or other antiviral agents (EIDD-2801, camostat, cycloheximide, or convalescent serum) showed strong synergy and effectively inhibited SARS-CoV-2 infection in human lung epithelial Calu-3 cells. Furthermore, we showed that the IFNa-remdesivir combination suppressed virus replication in human lung organoids, and that its single prophylactic dose attenuated SARS-CoV-2 infection in lungs of Syrian hamsters. Transcriptome and metabolomic analyses showed that the combination of IFNa-remdesivir suppressed virus-mediated changes in infected cells, although it affected the homeostasis of uninfected cells. We also demonstrated synergistic antiviral activity of IFNa2a-based combinations against other virus infections in vitro. Altogether, our results indicate that IFNa2a-based combination therapies can achieve higher efficacy while requiring lower dosage compared to monotherapies, making them attractive targets for further pre-clinical and clinical development.

Blood neurofilament light concentration at admittance: a potential prognostic marker in COVID-19 (preprint)

ObjectiveTo test the hypotheses that blood concentrations of neurofilament light chain protein (NfL) and glial fibrillary acidic protein (GFAp) can serve as biomarkers for disease severity in COVID-19 patients. MethodsForty-seven inpatients with confirmed COVID-19 had blood samples drawn on admission for assessing serum biomarkers of CNS injury by Single molecule array (Simoa). Concentrations of NfL and GFAp were analyzed in relation to symptoms, clinical signs, inflammatory biomarkers and clinical outcomes. We used multivariate linear models to test for differences in biomarker concentrations in the subgroups, accounting for confounding effects. ResultsIn total, 21 % (n = 10) of the patients were admitted to an intensive care unit, whereas the overall mortality rate was 13 % (n = 6). Non-survivors had higher serum concentrations of NfL than patients who were discharged alive both in adjusted analyses (p = 2.6 x 10-7) and unadjusted analyses (p = 0.001). Serum concentrations of GFAp were significantly higher in non-survivors than survivors in adjusted analyses (p = 0.02). The NfL concentrations in non-survivors increased over repeated measurements, whereas the concentrations in survivors were stable. Significantly higher concentrations of NfL were found in patients reporting fatigue, while reduced concentrations were found in patients experiencing cough, myalgia and joint pain. ConclusionIncreased concentrations of NfL and GFAp in COVID-19 patients on admission may indicate increased mortality risk. Measurement of blood biomarkers for nervous system injury can be useful to detect and monitor CNS injury in COVID-19.

Increased Interleukin-6 and Macrophage Chemoattractant Protein-1 are associated with Respiratory Failure in COVID-19 (preprint)

Background: In SARS-CoV-2 infection there is an urgent need to identify patients that will progress to severe COVID-19 and may benefit from targeted treatment.Objectives: Analyze plasma cytokines in COVID-19 patients and investigate their association with respiratory failure (RF) and treatment in Intensive Care Unit (ICU). Method: Hospitalized patients (n=34) with confirmed COVID-19 were recruited into a prospective cohort study. Clinical data and blood samples were collected at inclusion and after 2-5 and 7-10 days. RF was defined as PaO2/FiO2 ratio (P/F) <40kPa. Plasma cytokines were analyzed by a Human Cytokine 27-plex assay. Measurements and Results: COVID-19 patients with RF and/or treated in ICU showed overall increased systemic cytokine levels. Plasma IL-6, IL-8, G-CSF, MCP-1, MIP-1α levels were negatively correlated with P/F, whereas combinations of IL-6, IP-10, IL-1ra and MCP-1 showed the best association with RF in ROC analysis (AUC 0.79-0.80, p<0.05). During hospitalization the decline was most significant for IP-10 (P<0.001). Conclusion: Elevated levels of pro-inflammatory cytokines were present in patients with severe COVID-19. IL-6 and MCP-1 were inversely correlated with P/F with the largest AUC in ROC analyses and should be further explored as biomarkers to identify patients at risk for severe RF and as targets for improved treatment strategies.