The effect of renin-angiotensin-aldosterone system inhibitors on organ-specific ace2 expression in zebrafish and its implications for COVID-19

Evaluation of Angiotensin-Converting Enzyme 2 Expression In Vivo with Novel 68Ga-Labeled Peptides Originated from the Coronavirus Receptor-Binding Domain

Angiotensin-converting enzyme 2 (ACE2) is not only a key to the renin-angiotensin-aldosterone system and related diseases, but also the main entry point on cell surfaces for certain coronaviruses, including severe acute respiratory syndrome coronavirus (SARS-CoV) and SARS-CoV-2. By analyzing the different key binding sites from the receptor-binding domain (RBD) of SARS-CoV and SARS-CoV-2, nine new ACE2-targeting peptides (A1 to A9) were designed, synthesized and connected with a chelator, 1,4,7-triazacyclononane-N,N',N''-triacetic acid (NOTA). NOTA-A1, NOTA-A2, NOTA-A4, NOTA-A5, and NOTA-A8 were successfully labeled with [68Ga]Ga3+ and were used for biological evaluation. [68Ga]Ga-NOTA-A2, [68Ga]Ga-NOTA-A5, and [68Ga]Ga-NOTA-A8 showed specific binding to ACE2 via cell assays, and their binding sites and binding capacity were calculated by molecular docking and molecular dynamics simulations. In tumor-bearing mice, A549 tumors were visualized 60 min postinjection of [68Ga]Ga-NOTA-A2, [68Ga]Ga-NOTA-A5, or [68Ga]Ga-NOTA-A8. These peptides also accumulated in the organs with high-level ACE2 expression, confirmed by immunohistochemical stain. Among them, [68Ga]Ga-NOTA-A5 exhibited the highest tumor uptake and tumor/background ratio, and it successfully tracked the increased ACE2 levels in mice tissues after excessive Losartan treatment. In a first-in-human study, the distribution of [68Ga]Ga-NOTA-A5 was evaluated with positron emission tomography/computed tomography (PET/CT) in three participants without adverse events. 68Ga-labeled peptides originated from the coronavirus RBD, with [68Ga]Ga-NOTA-A5 as a typical representative, seem to be safe and effective for the evaluation of ACE2 expression in vivo with PET/CT, facilitating further mechanism investigation and clinical evaluation of ACE2-related diseases.

Biophysical Analysis of Potential Inhibitors of SARS-CoV-2 Cell Recognition and Their Effect on Viral Dynamics in Different Cell Types: A Computational Prediction from In Vitro Experimental Data

Recent reports have suggested that the susceptibility of cells to SARS-CoV-2 infection can be influenced by various proteins that potentially act as receptors for the virus. To investigate this further, we conducted simulations of viral dynamics using different cellular systems (Vero E6, HeLa, HEK293, and CaLu3) in the presence and absence of drugs (anthelmintic, ARBs, anticoagulant, serine protease inhibitor, antimalarials, and NSAID) that have been shown to impact cellular recognition by the spike protein based on experimental data. Our simulations revealed that the susceptibility of the simulated cell systems to SARS-CoV-2 infection was similar across all tested systems. Notably, CaLu3 cells exhibited the highest susceptibility to SARS-CoV-2 infection, potentially due to the presence of receptors other than ACE2, which may account for a significant portion of the observed susceptibility. Throughout the study, all tested compounds showed thermodynamically favorable and stable binding to the spike protein. Among the tested compounds, the anticoagulant nafamostat demonstrated the most favorable characteristics in terms of thermodynamics, kinetics, theoretical antiviral activity, and potential safety (toxicity) in relation to SARS-CoV-2 spike protein-mediated infections in the tested cell lines. This study provides mathematical and bioinformatic models that can aid in the identification of optimal cell lines for compound evaluation and detection, particularly in studies focused on repurposed drugs and their mechanisms of action. It is important to note that these observations should be experimentally validated, and this research is expected to inspire future quantitative experiments.

Zebrafish-based platform for emerging bio-contaminants and virus inactivation research

Emerging bio-contaminants such as viruses have affected health and environment settings of every country. Viruses are the minuscule entities resulting in severe contagious diseases like SARS, MERS, Ebola, and avian influenza. Recent epidemic like the SARS-CoV-2, the virus has undergone mutations strengthen them and allowing to escape from the remedies. Comprehensive knowledge of viruses is essential for the development of targeted therapeutic and vaccination treatments. Animal models mimicking human biology like non-human primates, rats, mice, and rabbits offer competitive advantage to assess risk of viral infections, chemical toxins, nanoparticles, and microbes. However, their economic maintenance has always been an issue. Furthermore, the redundancy of experimental results due to aforementioned aspects is also in examine. Hence, exploration for the alternative animal models is crucial for risk assessments. The current review examines zebrafish traits and explores the possibilities to monitor emerging bio-contaminants. Additionally, a comprehensive picture of the bio contaminant and virus particle invasion and abatement mechanisms in zebrafish and human cells is presented. Moreover, a zebrafish model to investigate the emerging viruses such as coronaviridae and poxviridae has been suggested.

Neuromasts and Olfactory Organs of Zebrafish Larvae Represent Possible Sites of SARS-CoV-2 Pseudovirus Host Cell Entry

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the acute respiratory disease coronavirus disease 2019 (COVID-19), which has resulted in millions of deaths globally. Here, we explored the mechanism of host cell entry of a luciferase-ZsGreen spike (SARS-CoV-2)-pseudotyped lentivirus using zebrafish embryos/larvae as an in vivo model. Successful pseudovirus entry was demonstrated via the expression of the luciferase (luc) gene, which was validated by reverse transcription-PCR (RT-PCR). Treatment of larvae with chloroquine (a broad-spectrum viral inhibitor that blocks membrane fusion) or bafilomycin A1 (a specific inhibitor of vacuolar proton ATPases, which blocks endolysosomal trafficking) significantly reduced luc expression, indicating the possible involvement of the endolysosomal system in the viral entry mechanism. The pharmacological inhibition of two-pore channel (TPC) activity or use of the tpcn2^dhkz1a mutant zebrafish line also led to diminished luc expression. The localized expression of ACE2 and TPC2 in the anterior neuromasts and the forming olfactory organs was demonstrated, and the occurrence of endocytosis in both locations was confirmed. Together, our data indicate that zebrafish embryos/larvae are a viable and tractable model to explore the mechanism of SARS-CoV-2 host cell entry, that the peripheral sense organs are a likely site for viral host cell entry, and that TPC2 plays a key role in the translocation of the virus through the endolysosomal system. IMPORTANCE Despite the development of effective vaccines to combat the COVID-19 pandemic, which help prevent the most life-threatening symptoms, full protection cannot be guaranteed, especially with the emergence of new viral variants. Moreover, some resistance to vaccination remains in certain age groups and cultures. As such, there is an urgent need for the development of new strategies and therapies to help combat this deadly disease. Here, we provide compelling evidence that the peripheral sensory organs of zebrafish possess several key components required for SARS-CoV-2 host cell entry. The nearly transparent larvae provide a most amenable complementary platform to investigate the key steps of viral entry into host cells, as well as its spread through the tissues and organs. This will help in the identification of key viral entry steps for therapeutic intervention, provide an inexpensive model for screening novel antiviral compounds, and assist in the development of new and more effective vaccines.

A randomized controlled trial of renin-angiotensin-aldosterone system inhibitor management in patients admitted in hospital with COVID-19

Background

Renin-angiotensin aldosterone system inhibitors (RAASi) are commonly used among patients hospitalized with a severe acute respiratory syndrome coronavirus 2 infection coronavirus disease 2019 (COVID-19). We evaluated whether continuation versus discontinuation of RAASi were associated with short term clinical or biochemical outcomes.

Methods

The RAAS-COVID-19 trial was a randomized, open label study in adult patients previously treated with RAASi who are hospitalized with COVID-19 (NCT04508985). Participants were randomized 1:1 to discontinue or continue RAASi. The primary outcome was a global rank score calculated from baseline to day 7 (or discharge) incorporating clinical events and biomarker changes. Global rank scores were compared between groups using the Wilcoxon test statistic and the negative binomial test (using incident rate ratio [IRR]) and the intention-to-treat principle.

Results

Overall, 46 participants were enrolled; 21 participants were randomized to discontinue RAASi and 25 to continue. Patients’ mean age was 71.5 years and 43.5% were female. Discontinuation of RAASi, versus continuation, resulted in a non-statistically different mean global rank score (discontinuation 6 [standard deviation [SD] 6.3] vs continuation 3.8 (SD 2.5); P = .60). The negative binomial analysis identified that discontinuation increased the risk of adverse outcomes (IRR 1.67 [95% CI 1.06-2.62]; P = .027); RAASi discontinuation increased brain natriuretic peptide levels (% change from baseline: +16.7% vs -27.5%; P = .024) and the incidence of acute heart failure (33% vs 4.2%, P = .016).

Conclusion

RAASi continuation in participants hospitalized with COVID-19 appears safe; discontinuation increased brain natriuretic peptide levels and may increase risk of acute heart failure; where possible, RAASi should be continued.

Association between Mineralocorticoid Receptor Antagonist and Mortality in SARS-CoV-2 Patients: A Systematic Review and Meta-Analysis

Since the onset of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, various potential targeted therapies for SARS-CoV-2 infection have been proposed. The protective effects of mineralocorticoid receptor antagonists (MRA) against tissue fibrosis, pulmonary and systemic vasoconstriction, and inflammation have been implicated in potentially attenuating the severity of SARS-CoV-2 infection by inhibiting the deleterious effects of aldosterone. Furthermore, spironolactone, a type of MRA, has been suggested to have a beneficial effect on SARS-CoV-2 outcomes through its dual action as an MRA and antiandrogen, resulting in reduced transmembrane protease receptor serine type 2 (TMPRSS2)-related viral entry to host cells. In this study, we sought to investigate the association between MRA antagonist therapy and mortality in SARS-CoV-2 patients via systematic review and meta-analysis. The systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. MEDLINE and EMBASE databases were searched for studies that reported the incidence of mortality in patients on MRA with SARS-CoV-2 infection. Pooled odds ratio (OR) and 95% confidence interval (CI) of the outcome were obtained using the random-effects model. Five studies with a total of 1,388,178 subjects (80,903 subjects receiving MRA therapy) met the inclusion criteria. We included studies with all types of MRA therapy including spironolactone and canrenone and found no association between MRA therapy and mortality in SARS-CoV-2 infection (OR = 0.387, 95% CI: 0.134–1.117, p = 0.079).

Angiotensin Converting Enzyme Inhibitors May Increase While Active Vitamin D May Decrease the Risk of Severe Pneumonia in SARS-CoV-2 Infected Patients with Chronic Kidney Disease on Maintenance Hemodialysis

The group most at risk of death due to COVID-19 are patients on maintenance hemodialysis (HD). The study aims to describe the clinical course of the early phase of SARS-CoV-2 infection and find predictors of the development of COVID-19 severe pneumonia in this population. This is a case series of HD nonvaccinated patients with COVID-19 stratified into mild pneumonia and severe pneumonia group according to the chest computed tomography (CT) pneumonia total severity score (TSS) on admission. Epidemiological, demographic, clinical, and laboratory data were obtained from hospital records. 85 HD patients with a mean age of 69.74 (13.19) years and dialysis vintage of 38 (14-84) months were included. On admission, 29.14% of patients had no symptoms, 70.59% reported fatigue followed by fever-44.71%, shortness of breath-40.0%, and cough-30.59%. 20% of the patients had finger oxygen saturation less than 90%. In 28.81% of patients, pulmonary parenchyma was involved in at least 25%. The factors associated with severe pneumonia include fever, low oxygen saturation and arterial partial pressure of oxygen, increased C-reactive protein and ferritin serum levels, low blood count of lymphocytes as well as chronic treatment with angiotensin converting enzyme inhibitors; while the chronic active vitamin D treatment was associated with mild pneumonia. In conclusion, even though nearly one-third of the patients were completely asymptomatic, while the remaining usually reported only single symptoms, a large percentage of them had extensive inflammatory changes at diagnosis with SARS-CoV-2 infection. We identified potential predictors of severe pneumonia, which might help individualize pharmacological treatment and improve clinical outcomes.