Circulating ACE2 activity predicts mortality and disease severity in hospitalized COVID-19 patients

The Predictive Value of Serum ACE2 and TMPRSS2 Concentrations in Patients with COVID-19-A Prospective Pilot Study

One of the major challenges for healthcare systems during the Coronavirus-2019 (COVID-19) pandemic was the inability to successfully predict which patients would require mechanical ventilation (MV). Angiotensin-Converting Enzyme 2 (ACE2) and TransMembrane Protease Serine S1 member 2 (TMPRSS2) are enzymes that play crucial roles in SARS-CoV-2 entry into human host cells. However, their predictive value as biomarkers for risk stratification for respiratory deterioration requiring MV has not yet been evaluated. We aimed to evaluate whether serum ACE2 and TMPRSS2 levels are associated with adverse outcomes in COVID-19, and specifically the need for MV. COVID-19 patients admitted to an Israeli tertiary medical center between March--November 2020, were included. Serum samples were obtained shortly after admission (day 0) and again following one week of admission (day 7). ACE2 and TMPRSS2 concentrations were measured with ELISA. Of 72 patients included, 30 (41.6%) ultimately required MV. Serum ACE2 concentrations >7.8 ng/mL at admission were significantly associated with the need for MV (p = 0.036), inotropic support, and renal replacement therapy. In multivariate logistic regression analysis, elevated ACE2 at admission was associated with the need for MV (OR = 7.49; p = 0.014). To conclude, elevated serum ACE2 concentration early in COVID-19 illness correlates with respiratory failure necessitating mechanical ventilation. We suggest that measuring serum ACE2 at admission may be useful for predicting the risk of severe disease.

A hypothesis that Notopterol may be effective in COVID-19 via JAK/STAT and other signaling pathways

COVID-19 is a rapidly spreading disease, causing a global pandemic. It is circulating in multiple countries and causing a series of respiratory infections. Due to the uncertain safety and efficacy of the vaccines and lack of specific medicines, it's important to investigate new pharmacological procedures and find out new drugs that help us eradicate this pandemic. We suggest the hypothesis that Notopterol (NOT), the main Secondary metabolite of Notopterygium incisum Ting ex H.T (a common Chinese medicinal herb), may have the potential benefits on SARS-CoV2 infection for this reasons: (a) NOT exhibits anti-inflammatory, anticancer, and anti-angiogenic properties, (b) NOT indicates a significant reduction in cytokines and chemokines releasing including TNFa, IL-6, interferon-γ, which may decrease COVID-19 cytokine storm (c) NOT can suppress the expression of genes which leads to inflammation via Janus kinase/signal transducers and activators of transcription (JAK-STAT) signaling pathway. It is exactly acting like tocilizumab, (an approved drug against COVID-19) and (d) Notopterygium incisum has antiviral activity against influenza virus, it can reduce the viral-induced oxidative stress. By these explanations, it is hopeful that NOT may be effective in COVID-19 infections which needs further investigations to examine Notopterol as a beneficial agent against the SARS-CoV2 infection.

Tryptophan Metabolism and COVID-19-Induced Skeletal Muscle Damage: Is ACE2 a Key Regulator?

The severity of coronavirus disease 2019 (COVID-19) is characterized by systemic damage to organs, including skeletal muscle, due to excessive secretion of inflammatory cytokines. Clinical studies have suggested that the kynurenine pathway of tryptophan metabolism is selectively enhanced in patients with severe COVID-19. In addition to acting as a receptor for severe acute respiratory syndrome coronavirus 2, the causative virus of COVID-19, angiotensin converting enzyme 2 (ACE2) contributes to tryptophan absorption and inhibition of the renin-angiotensin system. In this article, we review previous studies to assess the potential for a link between tryptophan metabolism, ACE2, and skeletal muscle damage in patients with COVID-19.

SARS-CoV-2 interacts with renin-angiotensin system: impact on the central nervous system in elderly patients

SARS-CoV-2 is a recently identified coronavirus that causes the current pandemic disease known as COVID-19. SARS-CoV-2 uses angiotensin-converting enzyme 2 (ACE2) as a receptor, suggesting that the initial steps of SARS-CoV-2 infection may have an impact on the renin-angiotensin system (RAS). Several processes are influenced by RAS in the brain. The neurological symptoms observed in COVID-19 patients, including reduced olfaction, meningitis, ischemic stroke, cerebral thrombosis, and delirium, could be associated with RAS imbalance. In this review, we focus on the potential role of disturbances in the RAS as a cause for central nervous system sequelae of SARS-CoV-2 infection in elderly patients.

An engineered ACE2 decoy receptor can be administered by inhalation and potently targets the BA.1 and BA.2 omicron variants of SARS-CoV-2

Monoclonal antibodies targeting the SARS-CoV-2 spike (S) glycoprotein neutralize infection and are efficacious for the treatment of mild-to-moderate COVID-19. However, SARS-CoV-2 variants have emerged that partially or fully escape monoclonal antibodies in clinical use. Notably, the BA.2 sublineage of B.1.1.529/omicron escapes nearly all monoclonal antibodies currently authorized for therapeutic treatment of COVID-19. Decoy receptors, which are based on soluble forms of the host entry receptor ACE2, are an alternative strategy that broadly bind and block S from SARS-CoV-2 variants and related betacoronaviruses. The high-affinity and catalytically active decoy sACE2 2 .v2.4-IgG1 was previously shown to be effective in vivo against SARS-CoV-2 variants when administered intravenously. Here, the inhalation of sACE2 2 .v2.4-IgG1 is found to increase survival and ameliorate lung injury in K18-hACE2 transgenic mice inoculated with a lethal dose of the virulent P.1/gamma virus. Loss of catalytic activity reduced the decoy’s therapeutic efficacy supporting dual mechanisms of action: direct blocking of viral S and turnover of ACE2 substrates associated with lung injury and inflammation. Binding of sACE2 2 .v2.4-IgG1 remained tight to S of BA.1 omicron, despite BA.1 omicron having extensive mutations, and binding exceeded that of four monoclonal antibodies approved for clinical use. BA.1 pseudovirus and authentic virus were neutralized at picomolar concentrations. Finally, tight binding was maintained against S from the BA.2 omicron sublineage, which differs from S of BA.1 by 26 mutations. Overall, the therapeutic potential of sACE2 2 .v2.4-IgG1 is further confirmed by inhalation route and broad neutralization potency persists against increasingly divergent SARS-CoV-2 variants.

Profiling of Lactate Dehydrogenase Isoenzymes in COVID-19 Disease

INTRODUCTION

Serum total lactate dehydrogenase (LDH) activity was elevated and showed a positive correlation with disease severity and outcome in severe COVID-19 disease. However, it is still unknown whether the relative abundance or calculated activity of any LDH isoenzyme is predominately increased in COVID-19 subjects.

METHODS

Twenty-two consecutive patients suffered from moderate or severe COVID-19 pneumonia were recruited into this study who showed enhanced total LDH activity. The ratio of LDH isoenzyme activities was further investigated using gel electrophoresis (Hydragel^®, Sebia) with densitometric evaluation. Calculated activity values of these isoenzymes were correlated with routine laboratory parameters, the degree of lung parenchymal affection based on chest CT and clinical outcome.

RESULTS

Total LDH activity was raised in the range of 272-2141 U/L and significantly correlated with calculated LDH-3 and LDH-4 activities (r=0.765, P=0.0001; and r=0.783, P=0.0001, respectively). In contrast, the relative abundance of neither LDH isoenzyme was exclusively abnormal in COVID-19 patients. Calculated activity of LDH-3 and LDH-4 demonstrated a modest but statistically significant association with serum ferritin (r=0.437, P=0.042; r=0.505, P=0.016, respectively). When the relationship between the severity of pulmonary affection by SARS-CoV-2 infection and relative abundance of LDH isoenzymes was studied, a larger ratio of mid-zone fractions was observed in the presence of ≥ 50% lung parenchymal involvement. Finally, regardless of LDH isoenzyme pattern, abnormal relative ratio of LDH-4 and higher calculated LDH-3 and LDH-4 activity values were detected in subjects with unfavorable outcome.

CONCLUSION

No characteristic profile of LDH isoenzymes can be detected in COVID-19 pneumonia, however, elevated activities of LDH-3 and LDH-4 are associated with worse clinical outcomes.