Downregulation Of Angiotensin-converting Enzyme 2 Research Articles

Association of ACE2 Gene Variants with Adverse Perinatal Outcomes in COVID-19 Infected Pregnant Women in Kazakhstan

SARS-CoV-2 utilizes the angiotensin-converting enzyme 2 (ACE2) receptors located on membranes to enter host cells. Nevertheless, the ACE2 gene primarily encodes for a zinc metalloproteinase, which is a part of the renin–angiotensin system (RAS). ACE2 downregulation results in the deregulation of RAS in favor of pro-fibrosis, pro-apoptosis, oxidative stress, pro-inflammation, aldosterone production and release, and blood vessel contraction axis. ACE2 is highly expressed in the placenta. There are both axes of the RAS system in the placenta. This study aims to assess the perinatal outcomes with ACE2 receptor polymorphisms in pregnant women infected with SARS-CoV-2 during pregnancy. The case-control study was conducted to determine the association of ACE2 single-nucleotide polymorphisms in 171 COVID-19-positive pregnant subjects and 112 control subjects. The recessive mutations of rs2158082 and rs4830974 were associated with an increased risk of low birthweight and preterm birth, whereas the dominant mutation of rs2285666 (CT + TT) was associated with decreased odds of low birthweight. COVID-19 was not a significant factor contributing to the adverse perinatal outcomes in our sampling. These findings may help to clarify the controversy regarding the increased risk of adverse perinatal outcomes observed during COVID-19 as well as provide new perspectives for research on the genetic factors associated with a higher risk of adverse perinatal outcomes.

Angiotensin-Converting Enzyme-2 (ACE2) Downregulation During Coronavirus Infection.

Angiotensin-converting enzyme-2 (ACE2) downregulation represents a detrimental factor in people with a baseline ACE2 deficiency associated with older age, hypertension, diabetes, and cardiovascular diseases. Human coronaviruses, including HCoV-NL63, SARS-CoV-1, and SARS CoV-2 infect target cells via binding of viral spike (S) glycoprotein to the ACE2, resulting in ACE2 downregulation through yet unidentified mechanisms. This downregulation disrupts the enzymatic activity of ACE2, essential in protecting against organ injury by cleaving and disposing of Angiotensin-II (Ang II), leading to the formation of Ang 1-7, thereby exacerbating the accumulation of Ang II. This accumulation activates the Angiotensin II type 1 receptor (AT1R) receptor, leading to leukocyte recruitment and increased proinflammatory cytokines, contributing to organ injury. The biological impacts and underlying mechanisms of ACE2 downregulation during SARS-CoV-2 infection have not been well defined. Therefore, there is an urgent need to establish a solid theoretical and experimental understanding of the mechanisms of ACE2 downregulation during SARS-CoV-2 entry and replication in the host cells. This review aims to discuss the physiological impact of ACE2 downregulation during coronavirus infection, the relationship between ACE2 decline and virus pathogenicity, and the possible mechanisms of ACE2 degradation, along with the therapeutic approaches.

Sivelestat protects against acute lung injury by up-regulating angiotensin-converting enzyme 2/angiotensin-(1-7)/Mas receptors.

Acute lung injury (ALI) and its most severe manifestation of acute respiratory distress syndrome (ARDS) is a disease with a clinical mortality rate of up to 40% and is one of the most dangerous and common complications of severe coronavirus disease 2019 (COVID-19). Sivelestat (SIV) is the only licensed therapeutic medicine in the world for ALI/ARDS treatment. The angiotensin-converting enzyme 2 (ACE2)/angiotensin (Ang)-(1-7)/Mas receptor axis is critical in the prevention of ALI/ARDS. This study aims to investigate whether SIV alleviates lipopolysaccharides (LPS)-induced ALI by inhibiting the down-regulation of ACE2/Ang-(1-7)/Mas receptor axis expression. In vivo, 90 male Sprague-Dawley rats were randomized into 5 groups. Then, we pretreated different groups of rats with dexamethasone (DEX) or SIV. Rats were sacrificed at three different time points (3, 6, and 12 hours) following LPS instillation. In vitro, RAW264.7 cells were divided into 11 groups. Different groups of cells were pretreated with DEX or SIV. And then added with LPS for 3, 6, and 12 hours. Next, we introduced A779, a potent Ang-(1-7) receptor antagonist, and DX600 as the ACE2 antagonist in different groups. Then the protein and messenger RNA (mRNA) expression levels of ACE2 in rat lung tissue and the expression levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and Ang-(1-7) in the rat serum and the cell culture supernatant were measured. And the data were statistically analyzed. In vivo, the rats pretreated with SIV or DEX had significantly lower lung wet/dry (W/D) ratios and lung pathological alterations than those exposed to LPS only. Both in vivo and in vitro, we observed that SIV or DEX significantly attenuated the LPS-induced up-regulation of IL-6 and TNF-α levels, and the down-regulation of ACE2 and Ang-(1-7) levels. In vitro, the pretreatment of the RAW264.7 cells with DX600 and A779 significantly reduced and even abolished the protective effects of SIV. Therefore, it was concluded that SIV protected against LPS-induced ALI and decreased inflammatory cytokine release by up-regulating the ACE2/Ang-(1-7)/Mas receptor axis. Our results enrich the theoretical foundation for the clinical application of SIV and provide fresh ideas for the treatment of ALI/ARDS.

Ubiquitination of angiotensin-converting enzyme 2 contributes to the development of pulmonary arterial hypertension mediated by neural precursor cell–expressed developmentally down-regulated gene 4-Like

ObjectivesIn this study, we investigated whether neural precursor cell–expressed developmentally down-regulated gene 4-like (NEDD4L) is the E3 enzyme of angiotensin-converting enzyme 2 (ACE2) and whether NEDD4L degrades ACE2 via ubiquitination, leading to the progression of pulmonary arterial hypertension (PAH).MethodsBioinformatic analyses were used to explore the E3 ligase that ubiquitinates ACE2. Cultured pulmonary arterial smooth muscle cells (PASMCs) and specimens from patients with PAH were used to investigate the crosstalk between NEDD4L and ACE2 and its ubiquitination in the context of PAH.ResultsThe inhibition of ubiquitination attenuated hypoxia-induced proliferation of PASMCs. The levels of NEDD4L were increased, and those of ACE2 were decreased in lung tissues from patients with PAH and in PASMCs. NEDD4L, the E3 ligase of ACE2, inhibited the expression of ACE2 in PASMCs, possibly through ubiquitination-mediated degradation. PAH was associated with upregulation of NEDD4L expression and downregulation of ACE2 expression.ConclusionsNEDD4L, the E3 ubiquitination enzyme of ACE2, promotes the proliferation of PASMCs, ultimately leading to PAH.

Serum Angiotensin II Level in Pediatric Patients with COVID-19 and its Correlation with the Disease Severity

Abstract Background Coronavirus disease 2019 (COVID-19) is a newly discovered RNA betacoronavirus infection. It has been caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Angiotensin II (Ang-II) is a mitochondrial toxin that under normal circumstances is rapidly removed by angiotensin converting enzyme 2 (ACE-2). SARS-CoV-2 uses the receptor ACE-2 for host cell entry and viral replication. ACE-2 proteins are occupied and downregulated by SARS-CoV-2. ACE-2 downregulation has been directly linked to toxic over accumulation of Ang-II. Accumulating Ang-II triggers many severe and fatal conditions such as acute respiratory distress syndrome (ARDS). Aim of the Work To assess the serum level of Ang-II and correlate it with the severity of COVID-19 infection in pediatric patients. Patients and Methods This case control study was conducted on 45 positive COVID-19 RT-PCR children who were compared to age and sex matched 45 healthy controls. Clinical examination, laboratory assays and imaging studies were done for the patients group to assess the severity of COVID–19 infection. Serum Ang-II was measured by ELISA for both groups and correlated with clinical (heart rate, blood pressure, respiratory rate and oxygen saturation), laboratory (total leucocytic count, lymphocytes, neutrophils, serum ferritin, ESR and CRP) and radiological (chest x-ray and CORAD score of CT chest ) parameters of the patients. Results The median “IQR” of serum Ang-II was significantly higher in the COVID-19 patients than in the controls (100 (88-137) ng/L) versus 20 (15-25) ng/L) (p-value= 0.001). There were statistically significant positive correlations between serum Ang-II levels and different grades of clinical severity classification (rs = 0.92, p-value=0.001) and CORAD score of CT chest. On the other hand, no statistically significant correlations were found between serum levels of Ang-II and total leucocytic count, lymphocytes, neutrophils, ESR and CRP. Conclusion Serum Ang-II could be used as a biomarker in predicting the severity of COVID-19 infection in pediatrics.

The flavonoid quercetin decreases ACE2 and TMPRSS2 expression but not SARS-CoV-2 infection in cultured human lung cells.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) binds to angiotensin-converting enzyme 2 (ACE2) on host cells, via its spike protein, and transmembrane protease, serine 2 (TMPRSS2) cleaves the spike-ACE2 complex to facilitate virus entry. As rate-limiting steps for virus entry, modulation of ACE2 and/or TMPRSS2 may decrease SARS-CoV-2 infectivity and COVID-19 severity. In silico modeling suggested the natural bioactive flavonoid quercetin can bind to ACE2 and a recent randomized clinical trial demonstrated that oral supplementation with quercetin increased COVID-19 recovery. A range of cultured human cells were assessed for co-expression of ACE2 and TMPRSS2. Immortalized Calu-3 lung cells, cultured and matured at an air-liquid interface (Calu-3-ALIs), were established as the most appropriate. Primary bronchial epithelial cells (PBECs) were obtained from healthy adult males (N = 6) and cultured under submerged conditions to corroborate the outcomes. Upon maturation or reaching 80% confluence, respectively, the Calu-3-ALIs and PBECs were treated with quercetin, and mRNA and protein expression were assessed by droplet digital PCR and ELISA, respectively. SARS-CoV-2 infectivity, and the effects of pre- and co-treatment with quercetin, was assessed by median tissue culture infectious dose assay. Quercetin dose-dependently decreased ACE2 and TMPRSS2 mRNA and protein in both Calu-3-ALIs and PBECs after 4 h, while TMPRSS2 remained suppressed in response to prolonged treatment with lower doses (twice daily for 3 days). Quercetin also acutely decreased ADAM17 mRNA, but not ACE, in Calu-3-ALIs, and this warrants further investigation. Calu-3-ALIs, but not PBECs, were successfully infected with SARS-CoV-2; however, quercetin had no antiviral effect, neither directly nor indirectly through downregulation of ACE2 and TMPRSS2. Calu-3-ALIs were reaffirmed to be an optimal cell model for research into the regulation of ACE2 and TMPRSS2, without the need for prior genetic modification, and will prove valuable in future coronavirus and respiratory infectious disease work. However, our data demonstrate that a significant decrease in the expression of ACE2 and TMPRSS2 by a promising prophylactic candidate may not translate to infection prevention.

Role of Inflammation in the Development of COVID-19 to Parkinson's Disease.

The coronavirus disease 2019 (COVID-19) can lead to neurological symptoms such as headaches, confusion, seizures, hearing loss, and loss of smell. The link between COVID-19 and Parkinson's disease (PD) is being investigated, but more research is needed for a definitive connection. Datasets GSE22491 and GSE164805 were selected to screen differentially expressed gene (DEG), and immune infiltration and gene set enrichment analysis (GSEA) of the DEG were performed. WGCNA analyzed the DEG and selected the intersection genes. Potential biological functions and signaling pathways were determined, and diagnostic genes were further screened using gene expression and receiver operating characteristic (ROC) curves. Screening and molecular docking of ibuprofen as a therapeutic target. The effectiveness of ibuprofen was verified by constructing a PD model in vitro, and constructing "COVID19-PD" signaling pathway, and exploring the role of angiotensin-converting enzyme 2 (ACE2) in PD. A total of 13 DEG were screened from the GSE36980 and GSE5281 datasets. Kyoto encyclopedia of genes and genomes (KEGG) analysis showed that the DEG were mainly associated with the hypoxia-inducible factor (HIF-1), epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor resistance, etc. After analysis, it is found that ibuprofen alleviates PD symptoms by inhibiting the expression of nuclear factor kappa-B (NF-κB), interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α). Based on signal pathway construction, the importance of ACE2 in COVID-19-induced PD has been identified. ACE2 is found to have widespread distribution in the brain. In the 1-methyl-4-phenyl-1,2,3,6-te-trahydropyridine (MPTP)-induced ACE2-null PD mice model, more severe motor and non-motor symptoms, increased NF-κB p65 and α-synuclein (α-syn) expression with significant aggregation, decreased tyrosine hydroxylase (TH), severe neuronal loss, and neurodegenerative disorders. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection increases the risk of PD through an inflammatory environment and downregulation of ACE2, providing evidence for the molecular mechanism and targeted therapy associated with COVID-19 and PD.

Differential Ability of Spike Protein of SARS-CoV-2 Variants to Downregulate ACE2.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 19 (COVID-19) and employs angiotensin-converting enzyme 2 (ACE2) as the receptor. Although the expression of ACE2 is crucial for cellular entry, we found that the interaction between ACE2 and the Spike (S) protein in the same cells led to its downregulation through degradation in the lysosomal compartment via the endocytic pathway. Interestingly, the ability of the S protein from previous variants of concern (VOCs) to downregulate ACE2 was variant-dependent and correlated with disease severity. The S protein from the Omicron variant, associated with milder disease, exhibited a lower capacity to downregulate ACE2 than that of the Delta variant, which is linked to a higher risk of hospitalization. Chimeric studies between the S proteins from the Delta and Omicron variants revealed that both the receptor-binding domain (RBD) and the S2 subunit played crucial roles in the reduced ACE2 downregulation activity observed in the Omicron variant. In contrast, three mutations (L452R/P681R/D950N) located in the RBD, S1/S2 cleavage site, and HR1 domain were identified as essential for the higher ACE2 downregulation activity observed in the Delta variant compared to that in the other VOCs. Our results suggested that dysregulation of the renin-angiotensin system due to the ACE2 downregulation activity of the S protein of SARS-CoV-2 may play a key role in the pathogenesis of COVID-19.

Sirt1 activation prevents high glucose-induced angiotensin converting enzyme 2 downregulation in renal tubular cells by regulating the TIMP3/ADAM17 pathway.

Angiotensin converting enzyme 2 (ACE2) exerts renoprotective effects in diabetic kidney disease (DKD) by converting angiotensin (Ang) II into Ang(1-7). Previous studies have demonstrated that ACE2 expression in renal tubules is downregulated in DKD, but the mechanism is not fully understood. Sirtuin-1 (Sirt1) is a protein deacetylase that may regulate the activity of the renin-angiotensin system. The present study investigated the effects of Sirt1 on ACE2 expression under high glucose (HG) conditions and the underlying signaling pathway. Rats with DKD and NRK-52E cells cultured with HG were employed in this study. Western blotting, immunohistochemistry detection and qRT-PCR were performed for protein and mRNA expression analyses. Rats subjected to DKD displayed downregulated expression of Sirt1 and ACE2 in kidneys. Resveratrol, an activator of Sirt1, restored ACE2 expression and ameliorated renal injuries. Similarly, pharmacological activation of Sirt1 with SRT1720 markedly upregulated ACE2 in NRK-52E cells cultured with HG, while Sirt1 small interfering RNA (siRNA) further suppressed ACE2 expression. In addition, A disintegrin and metalloproteinase (ADAM) 17 was observed to be upregulated, and its inhibitor, tissue inhibitor of metalloproteinase 3 (TIMP3), was downregulated in the kidneys of diabetic rats and NRK-52E cells incubated with HG. The TIMP3/ADAM17 pathway was involved in the regulation of ACE2 expression, as evidenced by decreased ACE2 expression levels after TIMP3-siRNA pretreatment. SRT1720 ameliorated the imbalance of TIMP3/ADAM17 induced by HG and consequently enhanced the expression of ACE2. Notably, the above effect of SRT1720 on ACE2 was interrupted by TIMP3-siRNA. Our findings suggest that Sirt1 activation may prevent HG-induced downregulation of renal tubular ACE2 by modulating the TIMP3/ADAM17 pathway. Sirt1 stimulation might be a potential strategy for the treatment of DKD.

SARS-CoV-2 Vaccination and the Multi-Hit Hypothesis of Oncogenesis.

Cancer is a complex and dynamic disease. The "hallmarks of cancer" were proposed by Hanahan and Weinberg (2000) as a group of biological competencies that human cells attain as they progress from normalcy to neoplastic transformation. These competencies include self-sufficiency in proliferative signaling, insensitivity to growth-suppressive signals and immune surveillance, the ability to evade cell death, enabling replicative immortality, reprogramming energy metabolism, inducing angiogenesis, and activating tissue invasion and metastasis. Underlying these competencies are genome instability, which expedites their acquisition, and inflammation, which fosters their function(s). Additionally, cancer exhibits another dimension of complexity: a heterogeneous repertoire of infiltrating and resident host cells, secreted factors, and extracellular matrix, known as the tumor microenvironment, that through a dynamic and reciprocal relationship with cancer cells supports immortality, local invasion, and metastatic dissemination. This staggering intricacy calls for caution when advising all people with cancer (or a previous history of cancer) to receive the COVID-19 primary vaccine series plus additional booster doses. Moreover, because these patients were not included in the pivotal clinical trials, considerable uncertainty remains regarding vaccine efficacy, safety, and the risk of interactions with anticancer therapies, which could reduce the value and innocuity of either medical treatment. After reviewing the available literature, we are particularly concerned that certain COVID-19 vaccines may generate a pro-tumorigenic milieu (i.e., a specific environment that could lead to neoplastic transformation) that predisposes some (stable) oncologic patients and survivors to cancer progression, recurrence, and/or metastasis. This hypothesis is based on biological plausibility and fulfillment of the multi-hit hypothesis of oncogenesis (i.e., induction of lymphopenia and inflammation, downregulation of angiotensin-converting enzyme 2 (ACE2) expression, activation of oncogenic cascades, sequestration of tumor suppressor proteins, dysregulation of the RNA-G quadruplex-protein binding system, alterationof type I interferon responses, unsilencing of retrotransposable elements, etc.) together with growingevidence and safety reports filed to Vaccine Adverse Effects Report System (VAERS) suggesting that some cancer patients experienced disease exacerbation or recurrence following COVID-19 vaccination. In light of the aboveand because some of these concerns (i.e., alteration of oncogenic pathways, promotion of inflammatory cascades, and dysregulation of the renin-angiotensin system) also apply to cancer patients infected with SARS-CoV-2, we encourage the scientific and medical community to urgently evaluate the impact of both COVID-19 and COVID-19 vaccination on cancer biology and tumor registries, adjusting public health recommendations accordingly.

Serum Soluble Angiotensin-Converting Enzyme-2 Level and Its Potential Association With The Renin-Angiotensin-Aldosterone System in Non-Hypertensive Iraqi COVID-19 Patients: An Observational Study

Background: The novel coronavirus disease (COVID-19) is caused by Severe acute respiratory syndrome coronavirus 2 (SARS-Cov2) which utilizes angiotensin converting enzyme2 (ACE2) to invade the host cells. This membrane-bound peptidase is widely distributed in the body; its activity antagonizes the renin-angiotensin-aldosterone system (RAAS). Once SARS-Cov2 enters the cell, it causes downregulation of ACE2, resulting in the unopposed activation of RAAS. The unregulated activity of the RAAS system can deteriorate the prognosis in COVID-19 patients. A soluble form of ACE2 (sACE2) was reported to have a role in the SARS-Cov2 invasion of the susceptible cells.
 Aim of the study: This study aims to investigate the potential association of serum levels of sACE2 and RAAS components in severe COVID-19 patients compared to healthy individuals.
 Methods: Eighty-five participants enrolled in the study were grouped into 45 non-hypertensive severe COVID-19 patients and 40 healthy individuals with comparable age and gender. Serum levels of sACE2, renin, angiotensin 2, and aldosterone by ELISA, and serum potassium level was measured by turbidimetric method.
 Results: The results showed a significant difference in the serum levels of sACE2 (lower), renin, angiotensin 2, and aldosterone (higher) in COVID-19 patients compared to the control subjects (p-value <0.001; for all.
 Conclusion: Non-hypertensive severe COVID-19 patients have lower sACE2 and higher RAAS peptide levels, and they can serve as diagnostic markers of severe COVID-19 patients.
 Recommendations: we recommend a future study with a larger sample size that enrolls COVID-19 patients with different severity levels.
 Keywords: Aldosterone, Angiotensin, COVID-19, Renin, Soluble angiotensin converting enzyme 2

Post-COVID-19 Syndrome vs. Consequences of Vaccination with Special Reference to Cardiovascular Conditions

Consequences of COVID-19 vaccination partly overlap with symptoms of post-COVID-19 syndrome. Putative mechanisms are also overlapping: endothelial damage and hyper coagulation, hypoxia, autoimmunity, inflammation, downregulation of angiotensin-converting enzyme.

Abstract P218: Ubr1 And Nedd4-2 Synergistically Modulate Ace2 Ubiquitination In Hypertensive Male Mice

Angiotensin-converting enzyme 2 (ACE2) is a counter-regulatory player in the renin-angiotensin system (RAS). Downregulation of ACE2 in hypertension results in vasoconstriction, sympathetic over-activation, and hypertension. Recently, we identified UBR1, an E3 ubiquitin-protein ligase, as a potential ubiquitinase modulating ACE2 expression, notably in hypertensive male mice where UBR1 is upregulated in the hypothalamus and peripheral organs. Here, we aim to understand the role of UBR1 in hypertension and its crosstalk with Nedd4-2, another E3 ligase regulating ACE2. C57BI/6J male mice (3 month-old, n=18) were implanted with telemetry probes for weekly 24 h BP recording. One week following baseline BP recording, mice were implanted with subcutaneous osmotic pumps containing Ang-II (600 ng/kg/min). After confirming hypertension, mice were divided into 4 treatment groups (n=6/group); 1) peripheral UBR1 siRNA via osmotic pump (50 μg/day/2 weeks), 2) central UBR1 siRNA via intracerebroventricular infusion (ICV) (50 μg/day/2 weeks) 3) scrambled shRNA + Ang-II, and 4) no treatment. After 6 weeks of BP recording, mice were euthanized, and hypothalami were harvested for protein analysis (Capillary Western). BP was transiently reduced during the resting phase after 3 weeks of ICV UBR1 siRNA infusion compared to the Ang-II group (MAP: 114±7 vs . 135±3 mmHg). Ang-II infusion enhanced UBR1 protein levels versus no treatment (Fold Change:1.6±0.1 vs . 1.0±0.04; p<0.05) which was prevented by peripheral and central UBR1 siRNA infusion, respectively (0.7±0.08, 1.3±0.08 vs. 1.6±0.1, p<0.05). Interestingly, while UBR1 siRNA infusion increased ACE2 expression (1.7±0.1, 2±0.2, p<0.01, respectively), it was also associated with increased Nedd4-2 levels ( 2.9±0.1, 3.5±0.2, p<0.0001, respectively), and pNedd4-2 (4.1±0.4, 3.8±0.5, p<0.001, respectively). Together, these data suggest that while prevention of UBR1 upregulation in hypertension is associated with an increase in ACE2 expression, it is not sufficient to permanently reduce BP as other E3 ligases, like Nedd4-2, appear to compensate for the knockdown.

Meta-Analysis of the Mechanisms Underlying COVID-19 Modulation of Parkinson's Disease.

Coronavirus disease-19 (COVID-19) is caused by the infection of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). The virus enters host cells through receptor-mediated endocytosis of angiotensin-converting enzyme-2 (ACE2), leading to systemic inflammation, also known as a "cytokine storm", and neuroinflammation. COVID-19's upstream regulator, interferon-gamma (IFNG), is downregulated upon the infection of SARS-CoV-2, which leads to the downregulation of ACE2. The neuroinflammation signaling pathway (NISP) can lead to neurodegenerative diseases, such as Parkinson's disease (PD), which is characterized by the formation of Lewy bodies made primarily of the α-synuclein protein encoded by the synuclein alpha (SNCA) gene. We hypothesize that COVID-19 may modulate PD progression through neuroinflammation induced by cytokine storms. This study aimed to elucidate the possible mechanisms and signaling pathways involved in COVID-19-triggered pathology associated with neurodegenerative diseases like PD. This study presents the analysis of the pathways involved in the downregulation of ACE2 following SARS-CoV-2 infection and its effect on PD progression. Through QIAGEN's Ingenuity Pathway Analysis (IPA), the study identified the NISP as a top-five canonical pathway/signaling pathway and SNCA as a top-five upstream regulator. Core Analysis was also conducted on the associated molecules between COVID-19 and SNCA to construct a network connectivity map. The Molecule Activity Predictor tool was used to simulate the infection of SARS-CoV-2 by downregulating IFNG, which leads to the predicted activation of SNCA, and subsequently PD, through a dataset of intermediary molecules. Downstream effect analysis was further used to quantify the downregulation of ACE2 on SNCA activation.

Altered renin-angiotensin system gene expression in airways of antigen-challenged mice: ACE2 downregulation and unexpected increase in angiotensin 1–7

ObjectiveEvidence suggest that the renin-angiotensin system (RAS) is activated in people with asthma, although its pathophysiological role is unclear. Angiotensin-converting enzyme 2 (ACE2) is the major enzyme that converts angiotensin II to angiotensin 1–7 (Ang-1–7), and is also known as a receptor of SARS-CoV-2. The current study was conducted to identify the change in RAS-related gene expression in airways of a murine asthma model. MethodsThe ovalbumin (OA)-sensitized mice were repeatedly challenged with aerosolized OA to induce asthmatic reaction. Twenty-four hours after the last antigen challenge, the main bronchial smooth muscle (BSM) tissues were isolated. ResultsThe KEGG pathway analysis of differentially expressed genes in our published microarray data revealed a significant change in the RAS pathway in the antigen-challenged mice. Quantitative RT-PCR analyses showed significant increases in the angiotensin II-generating enzymes (Klk1, Klk1b3 and Klk1b8) and a significant decrease in Ace2. Surprisingly, ELISA analyses revealed a significant increase in Ang-1–7 levels in bronchoalveolar lavage (BAL) fluids of the antigen-challenged animals, while no significant change in angiotensin II was observed. Application of Ang-1–7 to the isolated BSMs had no effect on their isometrical tension. ConclusionThe expression of Ace2 was downregulated in the BSMs of OA-challenged mice, while Klk1, Klk1b3 and Klk1b8 were upregulated. Despite the downregulation of ACE2, the level of its enzymatic product, Ang-1–7, was increased in the inflamed airways, suggesting the existence of an unknown ACE2-independent pathway for Ang-1–7 production. The functional role of Ang-1–7 in the airways remains unclear.

Brain Renin-Angiotensin System: From Physiology to Pathology in Neuronal Complications Induced by SARS-CoV-2.

Angiotensin-converting enzyme 2 (ACE2), a key enzyme in the renin-angiotensin system (RAS), is expressed in various tissues and organs, including the central nervous system (CNS). The spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for coronavirus disease-2019 (COVID-19), binds to ACE2, which raises concerns about the potential for viral infection in the CNS. There are numerous reports suggesting a link between SARS-CoV-2 infection and neurological manifestations. This study aimed to present an updated review of the role of brain RAS components, especially ACE2, in neurological complications induced by SARS-CoV-2 infection. Several routes of SARS-CoV-2 entry into the brain have been proposed. Because an anosmia condition appeared broadly in COVID-19 patients, the olfactory nerve route was suggested as an early pathway for SARS-CoV-2 entry into the brain. In addition, a hematogenous route via disintegrations in the blood-brain barrier following an increase in systemic cytokine and chemokine levels and retrograde axonal transport, especially via the vagus nerve innervating lungs, have been described. Common nonspecific neurological symptoms in COVID-19 patients are myalgia, headache, anosmia, and dysgeusia. However, more severe outcomes include cerebrovascular diseases, cognitive impairment, anxiety, encephalopathy, and stroke. Alterations in brain RAS components such as angiotensin II (Ang II) and ACE2 mediate neurological manifestations of SARS-CoV-2 infection, at least in part. Downregulation of ACE2 due to SARS-CoV-2 infection, followed by an increase in Ang II levels, leads to hyperinflammation and oxidative stress, which in turn accelerates neurodegeneration in the brain. Furthermore, ACE2 downregulation in the hypothalamus induces stress and anxiety responses by increasing corticotropin-releasing hormone. SARS-CoV-2 infection may also dysregulate the CNS neurotransmission, leading to neurological complications observed in severe cases of COVID-19. It can be concluded that the neurological manifestations of COVID-19 may be partially associated with changes in brain RAS components.

Significance of Furin Expression in Thyroid Neoplastic Transformation.

Angiotensin-Converting Enzyme 2 (ACE2), Transmembrane Serine Protease 2 (TMPRSS2), and Furin were known to be key players in the SARS-CoV-2 infection, and the thyroid gland was revealed to be one of the relevant targets of the virus. Regardless of the viral infection, the expression of these molecules in the thyroid gland and their putative role in the neoplastic transformation of the thyrocytes has not been thoroughly explored. In this work, we aimed to characterize the mRNA and protein expression pattern of ACE2, TMPRSS2, and Furin in a series of patients with thyroid lesions. Our main results revealed a significantly decreased expression of ACE2 mRNA in the thyroid neoplasms in comparison to normal adjacent tissue. Furin mRNA was significantly increased in thyroid neoplasms when compared to normal adjacent tissue. In addition, a higher Furin mRNA level in thyroid carcinomas was associated with the presence of lymph node metastasis. Furin mRNA expression revealed a high discriminatory power between adjacent tissue and neoplasms. Protein expression of these molecules did not correlate with mRNA expression. Our study shows the mRNA downregulation of ACE2 and overexpression of Furin in thyroid neoplasms. Further studies are required to clarify if Furin expression can be a potential diagnostic indicator in thyroid neoplasia.

Functional characterisation of the ACE2 orthologues in Drosophila provides insights into the neuromuscular complications of COVID-19

SARS-CoV-2, the virus responsible for the coronavirus disease of 2019 (COVID-19), gains cellular entry via interaction with the angiotensin-converting enzyme 2 (ACE2) receptor of host cells. Although SARS-CoV-2 mainly targets the respiratory system, the neuromuscular system also appears to be affected in a large percentage of patients with acute or chronic COVID-19. The cause of the well-described neuromuscular manifestations resulting from SARS-CoV-2 infection remains unresolved. These may result from the neuromuscular-invasive capacity of the virus leading to direct injury. Alternatively, they may be the consequence of ACE2 inactivation either due to viral infection, ACE2 autoantibodies or both. Here, we made use of the Drosophila model to investigate whether ACE2 downregulation is sufficient to induce neuromuscular phenotypes. We show that moderate gene silencing of ACE2 orthologues Ance or Ance3 diminished survival on exposure to thermal stress only upon induction of neuromuscular fatigue driven by increased physical activity. A strong knockdown of Ance or Ance3 directed to muscle reduced or abolished adult viability and caused obvious motoric deficits including reduced locomotion and impaired flight capacity. Selective knockdown of Ance and Ance3 in neurons caused wing defects and an age-dependent decline in motor behaviour, respectively, in adult flies. Interestingly, RNA sequencing allowed us to discover several differentially spliced genes that are required for synaptic function downstream of Ance or Ance3 depletion. Our findings are therefore supportive of the notion that loss of a RAS-independent function for ACE2 contributes to the neuromuscular manifestations associated with SARS-CoV-2 infection.

Utilization of Marine Seaweeds as a Promising Defense Against COVID-19: a Mini-review.

COVID-19 is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which mainly affects the respiratory system. It has been declared as a "pandemic" in March 2020 by the World Health Organization due to the high spreading rate. SARS-CoV-2 binds with the angiotensin-converting enzyme 2 (ACE2) receptors on the cell surface which leads to the downregulation of ACE2 and upregulation of angiotensin-converting enzyme (ACE) receptors. The elevated level of cytokines and ACE receptors leads to the severity of SARS-CoV-2 infection. Due to the limited availability of vaccines and recurrent attacks of COVID-19 mainly in low-income countries, it is important to search for natural remedies to prevent or treat COVID-19 infection. Marine seaweeds are a rich source of bioactive compounds such as phlorotannins; fucoidan; carotenoids; omega-3 and omega-6 fatty acids; vitamins B12, D, and C; and minerals including zinc and selenium that exhibit antioxidant, antiviral, and anti-inflammatory activities. Furthermore, bioactive compounds present in marine seaweeds have the ability to inhibit ACEs by inducing ACE2 which exhibits anti-inflammatory effects in COVID-19. Correspondingly, soluble dietary fibers present in seaweeds are served as prebiotics by generating short-chain fatty acids through fermentation. Hence, seaweeds can be utilized to reduce the gastrointestinal infections associated with SARS-CoV-2 infection.

SIM imaging resolves endocytosis of SARS-CoV-2 spike RBD in living cells

It is urgent to understand the infection mechanism of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) for the prevention and treatment of COVID-19. The infection of SARS-CoV-2 starts when the receptor-binding domain (RBD) of viral spike protein binds to angiotensin-converting enzyme 2 (ACE2) of the host cell, but the endocytosis details after this binding are not clear. Here, RBD and ACE2 were genetically coded and labeled with organic dyes to track RBD endocytosis in living cells. The photostable dyes enable long-term structured illumination microscopy (SIM) imaging and to quantify RBD-ACE2 binding (RAB) by the intensity ratio of RBD/ACE2 fluorescence. We resolved RAB endocytosis in living cells, including RBD-ACE2 recognition, cofactor-regulated membrane internalization, RAB-bearing vesicle formation and transport, RAB degradation, and downregulation of ACE2. The RAB was found to activate the RBD internalization. After vesicles were transported and matured within cells, RAB was finally degraded after being taken up by lysosomes. This strategy is a promising tool to understand the infection mechanism of SARS-CoV-2.