Receptor Angiotensin-converting Enzyme Research Articles

Cyclophilin–CD147 interaction enables SARS-CoV-2 infection of human monocytes and their activation via Toll-like receptors 7 and 8

Monocytes and macrophages, as important constituents of the innate immune system, are equipped with multiple Toll-like-receptors (TLRs) to recognize invading pathogens, such as SARS-CoV-2, and mount an antiviral response. Nevertheless, their uncontrolled activation can lead to hyperinflammation seen in severe COVID-19. Surprisingly, we observed that recombinant SARS-CoV-2 Spike (S) and Nucleocapsid (N) proteins triggered only a weak proinflammatory response in human peripheral blood monocytes. By employing THP-1 and Jurkat NF-κB::eGFP reporter cell lines expressing specific TLRs, various TLR ligands and blocking antibodies, we determined that surface TLRs, including TLR2/1, TLR2/6 and TLR4 do not play a major role in SARS-CoV-2 sensing. However, monocytes are potently activated by the replication-competent SARS-CoV-2, and the response correlates with the viral uptake that is observed only in monocytes, but not in lymphocytes. We show that monocyte activation involves two distinct steps. Firstly, SARS-CoV-2 infects monocytes in a process independent of the S protein and the prime SARS-CoV-2 receptor angiotensin-converting enzyme 2. Instead, the alternative SARS-CoV-2 receptor CD147, which is highly expressed on monocytes, recognizes its well-known interaction partners cyclophilins A and B that are incorporated into SARS-CoV-2 virions. Secondly, upon viral uptake via the cyclophilin-CD147 interaction, that can be inhibited by specific CD147 blocking antibodies or competition with recombinant human cyclophilin A and B, SARS-CoV-2 RNA is recognized by TLR7/8 in endosomes, leading to upregulation of tumor necrosis factor (TNF), interleukin (IL)-1β and IL-6, comprising the core hyperinflammatory signature. Taken together, our data reveal a novel mechanism how human monocytes sense SARS-CoV-2 and suggest that targeting the cyclophilin-CD147 axis might be beneficial to alleviate overt myeloid-driven inflammation triggered by SARS-CoV-2 infection.

Coronil effectively inhibits the interaction of clinically relevant Omicron mutants of SARS-CoV-2 Spike Proteins with human ACE2 receptor

BackgroundAccumulating evidence suggests that the receptor binding domain (RBD) of the SARS-CoV-2 Omicron variant has several times more binding affinity to the human angiotensin-converting enzyme 2 (ACE2) receptor compared to the RBD of the original covid-19 strain. This increased binding affinity of the Omicron variant is responsible for its increased internalization and infectivity. PurposeIn the present study, the impact of Coronil, a tri-herbal formulation of extracts from Withania somnifera, Tinospora cordifolia and Ocimum sanctum on the binding properties of Omicron SARS-CoV-2 variant spike proteins (S proteins) was investigated. MethodsChemical composition of Coronil was determined by the Prominence-XR UHPLC system. The ELISA-based ACE2 binding inhibition assay was performed to delineate the effect of Coronil on the interaction between human ACE2 receptor and different Omicron variant S-proteins such as BA.4/BA5, XBB, BA.2.75.2, BA4.6/BF.7, BA.2.75.2, BQ.1.1 and a recently found spike protein variant JN.1 which is thought to emerge from BA.2.86. ResultsCoronil showed a dose-dependent inhibitory effect on the interactions between ACE2 and receptor binding domains (RBD) of all variants of S-proteins evaluated in this study including the recently emerged, highly transmissible variant spike protein JN.1. Although, Coronil significantly reduced the binding percentage in almost all the variant spike proteins, the maximum inhibition was achieved against BA.4/BA.5 where it inhibited the S protein – ACE2 interaction even at a low concentration of 3 µg/ml (16.6 %). This binding inhibition was further increased to 60.3 and 84.6 % at 100 and 300 µg/ml respectively. ConclusionThis capability of Coronil to inhibit the binding of S-protein variants with ACE2 receptor may interfere with viral binding and internalization resulting in reduced infectivity of these Omicron spike protein variants. Overall, our data underscores the potential of Coronil in combating the various newly emerged Omicron spike protein variants. These findings may provide a basis for further studies of Coronil for its clinical effectiveness against these Omicron variants.

Clinical Trial to Evaluate Safety and Efficacy of Thinqure20 (A Herbal Composition) in the Treatment and Prophylaxis of Novel Coronavirus and Testing its In vitro- Potential against MS2 Bacteriophagae, Corona Virus, Influenza Virus and Mucor racemosus

Background and Objective: Thinqure20 is a polyherbal, reverse-pharmacology-based formulation that contains Piper longum, Piper nigrum, Zingiber officinale, and rock salt as active ingredients. It is designed to work as an effective antiviral agent and also as a preventive measure against SARS-CoV-2. Clinical and non-clinical studies have established significant safety efficacy and tolerability of Thinqure20 formulation in the treatment of COVID-19 infection. Methods: In vivo human study was conducted on COVID-19 patients for 5 days. A total of 30 Covid-19 patients (n = 30) were enrolled. In vitro, cell line studies were also carried out to evaluate the potential effectiveness of Thinqure20 polyherbal formulation as an antiviral, antifungal, and Angiotensin- Converting Enzyme 2 (ACE2) inhibition. Results: Human studies have demonstrated a mean percentage of reduction in viral load from baseline to end of the study visit which was found to be 75.4%. The minimum and maximum reduction in viral load was found to be 59.3% and 100%, respectively. Viral load testing was carried out by Reverse Transcriptase-quantitative Polymerase Chain Reaction (RT-qPCR) test. In vitro studies of Thinqure, 20 extracts showed potential antiviral activity against MS2 bacteriophage, influenza, and human coronavirus, antifungal activity against Mucor racemosus, and significant ACE2 receptor inhibition. Conclusion: Thinqure20, a polyherbal formulation, is a potentially effective antiviral agent against non-enveloped viruses (MS2 bacteriophage), enveloped viruses (influenza and human coronavirus), and antifungal agent against mucor strains. It is also proven to be effective in the treatment of COVID-19 and can be attributed to an early recovery by the reduction in viral load.

The Effect of the Concurrent Use of Angiotensin-Converting Enzyme Inhibitors or Receptor Blockers on Toxicity and Outcomes in Patients Treated with Radiotherapy: A Systematic Review and Meta-Analysis.

Background/Objectives: ACEIs protect against radiation pneumonitis by reducing angiotensin II production, oxidative stress, and inflammation. This study highlights the significance of concurrent angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB) use in radiotherapy by evaluating its impact on radiotherapy-related side effects and survival outcomes, addressing the gap in existing research and providing insights to guide clinical practice in oncology. Methods: The literature was retrieved from the MEDLINE, EMBASE, Web of Science, and Scopus databases from January 2000 to October 2024. Studies on adults (≥18 years) with histologically confirmed cancer, receiving ACEIs or ARBs during radiotherapy, were included. Radiotherapy-related side effects and clinical outcomes were analysed using odds ratios (ORs) and 95% confidence intervals (95%CIs), comparing ACEI/ARB users to non-users. Differences in the median survival time, recurrence, and death rates were also calculated. Results: Sixteen studies (14 cohort studies and two randomised trials) were included. ACEI users exhibited a 50% reduction in the risk of ≥grade 2 radiation pneumonitis (OR: 0.50, 95%CI: 0.32-0.77) in lung cancer and significant reductions in the odds of proctitis (80%, OR: 0.20, 95%CI: 0.12-0.33), haematuria (75%, OR: 0.25, 95%CI: 0.16-0.41), and rectal bleeding (61%, OR: 0.39, 95%CI: 0.30-0.51) in prostate cancer. ACEI/ARB users showed reduced symptomatic radiation necrosis in brain metastases and better 6-month functional independence in supratentorial glioblastoma. Among six studies reporting survival, ACEI/ARB users had longer median survival in early-stage non-small-cell lung cancer and glioblastoma but shorter survival in small cell lung cancer and brain metastases. ARB users had inconsistent survival rates for lung cancer. The varying survival outcomes suggest that ACEIs/ARBs have different effects depending on the cancer type and stage, potentially influenced by cancer-specific factors, treatment protocols, or disease progression. Conclusions: ACEI use is associated with a reduction in radiation pneumonitis, but evidence for other radiotherapy-related toxicity and survival outcomes remains inconsistent across cancer types and severities. Further research should carefully control for confounders.

Green Synthesis of Tetrahydropyrazino[2,1-a:5,4-a']diisoquinolines as SARS-CoV-2 Entry Inhibitors.

A class of tetrahydropyrazino[2,1-a:5,4-a']diisoquinoline derivatives were synthesized under environmentally friendly conditions using water as the solvent. The 3-D structures of some synthesized compounds were determined by X-ray diffraction. Since naturally occurring isoquinoline alkaloids have significant antiviral activities against a wide range of viruses, including coronaviruses, the synthesized compounds were assayed for their inhibitory activities against SARS-CoV-2. Our results showed that the active compounds 50 and 96 blocked the delta SARS-CoV-2 entry into VeroE6 cells to display EC50 of 26.5 ± 6.9 and 17.0 ± 3.7 μM, respectively, by inhibiting the interaction between SARS-CoV-2 Spike's receptor binding domain (RBD) and human receptor angiotensin-converting enzyme 2 (ACE2), and CC50 greater than 100 μM. This study provides a green synthesis method of tetrahydropyrazinodiisoquinoline for antiviral or other applications.

COVID-19 in patients with multiple sclerosis-A narrative review.

Multiple sclerosis (MS) is a complex neurodegenerative disease characterized by immune dysregulation, affecting over 2.5 million people worldwide. Interestingly, COVID-19 infection can cause neurodegeneration through demyelination similar to that of MS, and COVID-19 infection can lead to long-term neurological sequelae, post-COVID-19 neurological syndrome. These overlapping neurological mechanisms suggest that patients with MS (PwMS) may have a unique and potentially more complex relationship with COVID-19. The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) can enter the central nervous system via the olfactory nerve or through interactions with angiotensin-converting enzyme-2 receptors in the blood-brain barrier, potentially initiating or enhancing neurodegenerative processes through demyelination. The risk of SARS-CoV-2 infection among PwMS is similar to that of the general population; however, PwMS with higher Expanded Disability Status Scale scores, longer MS duration, or progressive forms of MS are at an increased risk for developing severe COVID-19 outcomes. Most disease-modifying therapies (DMT), such as interferon, glatiramer, teriflunomide, and cladribine, do not appear to affect the risk of COVID-19 infection, the severity of COVID-19 illness, or the response to COVID-19 vaccines. As a result, these therapies should be continued during COVID-19 infection in PwMS. Rituximab, however, has been shown to increase the risk of severe COVID-19 outcomes. For managing symptomatic COVID-19 infection in PwMS, remdesivir and neutralizing monoclonal antibodies are shown to be effective. COVID-19-associated cytokine release syndrome can be managed with corticosteroids. Importantly, COVID-19 infection does not increase susceptibility to MS relapses or exacerbate the progression of MS symptoms. Furthermore, COVID-19 vaccination is encouraged for all MS patients, particularly those at greater risk of severe outcomes, as it does not trigger relapses, exacerbate MS symptoms, or diminish the efficacy of DMT. Despite these findings, high-quality evidence remains lacking to fully establish the relationship between COVID-19 and MS, highlighting the need for further research in this area.

Evolution of SARS-CoV-2 spike trimers towards optimized heparan sulfate cross-linking and inter-chain mobility

The heparan sulfate (HS)-rich extracellular matrix (ECM) serves as an initial interaction site for the homotrimeric spike (S) protein of SARS-CoV-2 to facilitate subsequent docking to angiotensin-converting enzyme 2 (ACE2) receptors and cellular infection. More recent variants, notably Omicron, have evolved by swapping several amino acids to positively charged residues to enhance the interaction of the S-protein trimer with the negatively charged HS. However, these enhanced interactions may reduce Omicron’s ability to move through the HS-rich ECM to effectively find ACE2 receptors and infect cells, raising the question of how to mechanistically explain HS-associated viral movement. In this work, we show that Omicron S proteins have evolved to balance HS interaction stability and dynamics, resulting in enhanced mobility on an HS-functionalized artificial matrix. This property is achieved by the ability of Omicron S-proteins to cross-link at least two HS chains, allowing direct S-protein switching between chains as a prerequisite for cell surface mobility. Optimized HS interactions can be targeted pharmaceutically, as an HS mimetic significantly suppressed surface binding and cellular infection specifically of the Omicron variant. These findings suggest a robust way to interfere with SARS-CoV-2 Omicron infection and potentially future variants.

Histopathological Evaluation of Pulmonary Arterial Remodeling in COVID-19.

A positive-sense single-stranded RNA virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), caused the coronavirus disease 2019 (COVID-19) pandemic that devastated the world. While this is a respiratory virus, one feature of the SARS-CoV-2 infection was recognized to cause pathogenesis of other organs. Because the membrane fusion protein of SARS-CoV-2, the spike protein, binds to its major host cell receptor angiotensin-converting enzyme 2 (ACE2) that regulates a critical mediator of cardiovascular diseases, angiotensin II, COVID-19 is largely associated with vascular pathologies. In fact, we have previous reported that postmortem lung tissues collected from patients who died of COVID-19 exhibited thickened pulmonary vascular walls and reduced vascular lumen. The present study extended these findings by further characterizing the pulmonary vasculature of COVID-19 patients using larger sample sizes and providing mechanistic information through histological observations. The examination of 56 autopsy lung samples showed thickened vascular walls of small pulmonary arteries after 14 days of disease compared to H1N1 influenza patients who died before COVID- 19 pandemic started. Pulmonary vascular remodeling in COVID-19 patients was associated with hypertrophy of the smooth muscle layer, perivascular fibrosis, edema and lymphostasis, inflammatory infiltration, perivascular hemosiderosis and neoangiogenesis. We found a correlation between the duration of hospital stay and the thickness of the muscular layer of pulmonary arterial walls. These results further confirm that COVID-19 affects the pulmonary vasculature and warrants an evaluation of patients that survived COVID-19 for possible future development of pulmonary arterial hypertension.

Bioinformatic characterization of ENPEP, the gene encoding a potential cofactor for SARS-CoV-2 infection.

Research on SARS-CoV-2, the viral pathogen that causes COVID-19, has identified angiotensin converting enzyme 2 (ACE2) as the primary viral receptor. Several genes that encode viral cofactors, such as TMPRSS2, NRP1, CTSL, and possibly KIM1, have since been discovered. Glutamyl aminopeptidase (APA), encoded by the gene ENPEP, is another cofactor candidate due to similarities in its biological role and high correlation with ACE2 and other human coronavirus receptors, such as aminopeptidase N (APN) and dipeptidyl peptidase 4 (DPP4). Recent studies have proposed a role for ENPEP as a viral receptor in humans, and ENPEP and ACE2 are both closely involved in the renin-angiotensin-aldosterone system proposed to play an important role in SARS-CoV-2 pathophysiology. We performed bioinformatic analyses using publicly available bulk (>17,000 samples from 49 distinct tissues) and single-cell (>2.5 million cells) RNA-Seq gene expression datasets to evaluate the expression and function of the ENPEP gene. We also investigated age- and sex-related changes in ENPEP expression. Overall, expression of ENPEP was highest in the small intestine enterocyte brush border and the kidney cortex. ENPEP is widely expressed in a subset of vascular smooth muscle cells (likely pericytes) in systemic vasculature, the heart, and the brain. ENPEP is expressed at low levels in the lower respiratory epithelium. In the lung, ENPEP is most highly expressed in para-alveolar fibroblasts. Single-cell data revealed ENPEP expression in a substantial fraction of ependymal cells, a finding not reported before in humans. Age increases ENPEP expression in skeletal muscle and the prostate, while decreasing it in the heart and aorta. Angiogenesis was found to be a central biological function associated with the ENPEP gene. Tissue-specific roles, such as protein digestion and fat metabolism, were also identified in the intestine. In the liver, the gene is linked to the complement system, a connection that has not yet been thoroughly investigated. Expression of ENPEP and ACE2 is strongly correlated in the small intestine and renal cortex. Both overall and in blood vessels, ENPEP and ACE2 have a stronger correlation than many other genes associated with SARS-CoV-2, such as TMPRSS2, CTSL, and NRP1. Possible interaction between glutamyl aminopeptidase and SARS-CoV-2 should be investigated experimentally.

Does COVID-19 reduce anti-Mullerian hormone levels in women of reproductive age in late periods of infection?

The question of whether severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection influences ovarian function and oocyte quality has arisen as angiotensin converting enzyme-2 receptors, which facilitates viral infection, are found on reproductive system tissues, including the vagina, placenta, uterus, and ovaries. The primary objective of this prospective study was to evaluate the impact of SARS-CoV-2, on ovarian function, with a focus on anti-Mullerian hormone (AMH) and acute phase reactant levels in patients well after recovery from coronavirus disease-2019 (COVID-19). This prospective cohort study was conducted in the department of obstetrics and gynecology at a single center between October 2020 and June 2021. In order to investigate the impact of COVID-19 on ovarian reserve, 34 non-pregnant women of reproductive age (24-38 years) with COVID-19 polymerase chain reaction positivity were included. The difference between AMH levels measured 6 months after COVID-19 infection and baseline AMH levels was -0.31±0.80 ng/dL on average and -0.25 (-2.1-1.3) ng/dL on median. Significant correlations were observed between the change in AMH levels and white blood cell levels (r=-0.434, p=0.010), lymphocyte levels (r=-0.361, p=0.036), C-reactive protein levels (r=0.542, p=0.001), ferritin levels (r=0.570, p=0.001) and procalcitonin levels (r=0.598, p=0.001). We believe this is the first study to examine whether there is a correlation between the late results of COVID-19 and ovarian function. In this cohort, AMH values decreased 6-months after recovery from COVID-19 and a correlation was found between measures of disease severity and the magnitude of decrease in AMH. However, the study was underpowered and future larger studies are required to validate these findings.

Altered plasma levels of the SARS-CoV-2-related proteins ACE2 and TMPRSS2 in patients with Crohn’s disease

The SARS-CoV-2 coronavirus infects cells through the cellular receptor angiotensin-converting enzyme 2 (ACE2), and the protease TMPRSS2 for the priming of viral spike protein. Thus, changes in these key proteins due to chronic conditions can increase risk for SARS-CoV2 infection; but significance of changes may differ is these changes correspond to full-length species or proteolytic fragments. Here, we determined that full-length ACE2 decreased in the plasma of uninfected Crohn’s disease (CD) patients before treatment onset compared to controls. TMPRSS2 is mostly presented in plasma as full-length species and as an active peptidase fragment, but also as a prodomain fragment, which is the unique species remarkably decreased in plasma from CD patients. Patients treated with the anti-TNFα adalimumab showed recovery in ACE2 levels, while those treated with infliximab, or with the anti-IL-12/23 ustekinumab, still displayed a decrease in full-length species, as well as in cleaved fragments. Patients treated with azathioprine displayed similar ACE2 levels to that of controls, except a decrease in one of the ACE2 fragments. Uniquely, patients treated with azathioprine or with ustekinumab showed partial recovery in the reduction of the TMPRSS2-prodomain fragment characterized in treatment-naïve patients. Our data suggest that CD and common therapies are not related to increased susceptibility for SARS-CoV-2.

Impedimetric Sensor for SARS-CoV-2 Spike Protein Detection: Performance Assessment with an ACE2 Peptide-Mimic/Graphite Interface.

The COVID-19 pandemic has prompted the need for the development of new biosensors for SARS-CoV-2 detection. Particularly, systems with qualities such as sensitivity, fast detection, appropriate to large-scale analysis, and applicable in situ, avoiding using specific materials or personnel to undergo the test, are highly desirable. In this regard, developing an electrochemical biosensor based on peptides derived from the angiotensin-converting enzyme receptor 2 (ACE2) is a possible answer. To this end, an impedimetric detector was developed based on a graphite electrode surface modified with an ACE2 peptide-mimic. This sensor enables accurate quantification of recombinant 2019-nCoV spike RBD protein (used as a model analyte) within a linear detection range of 0.167-0.994 ng mL-1, providing a reliable method for detecting SARS-CoV-2. The observed sensitivity was further demonstrated by molecular dynamics that established the high affinity and specificity of the peptide to the protein. Unlike other impedimetric sensors, the herein presented system can detect impedance in a single frequency, allowing a measure as fast as 3 min to complete the analysis and achieving a detection limit of 45.08 pg mL-1. Thus, the proposed peptide-based electrochemical biosensor offers fast results with adequate sensitivity, opening a path to new developments concerning other viruses of interest.

Discovery of a Potential Allosteric Site in the SARS-CoV-2 Spike Protein and Targeting Allosteric Inhibitor to Stabilize the RBD Down State using a Computational Approach.

The novel coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to a worldwide public health crisis. At present, the development of effective drugs and/or related therapeutics is still the most urgent and important task for combating the virus. The viral entry and associated infectivity mainly rely on its envelope spike protein to recognize and bind to the host cell receptor angiotensin-converting enzyme 2 (ACE2) through a conformational switch of the spike receptor binding domain (RBD) from inactive to active state. Thus, it is of great significance to design an allosteric inhibitor targeting spike to lock it in the inactive and ACE2-inaccessible state. This study aims to discover the potential broad-spectrum allosteric inhibitors capable of binding and stabilizing the diverse spike variants, including the wild type, Delta, and Omicron, in the inactive RBD down state. In this work, we first detected a potential allosteric pocket within the SARS-CoV-2 spike protein. Then, we performed large-scale structure-based virtual screening by targeting the putative allosteric pocket to identify allosteric inhibitors that could stabilize the spike inactive state. Molecular dynamics simulations were further carried out to evaluate the effects of compound binding on the stability of spike RBD. Finally, we identified three potential allosteric inhibitors, CPD3, CPD5, and CPD6, against diverse SARS-CoV-2 variants, including Wild-type, Delta, and Omicron variants. Our simulation results showed that the three compounds could stably bind the predicted allosteric site and effectively stabilize the spike in the inactive state. The three compounds provide novel chemical structures for rational drug design targeting spike protein, which is expected to greatly assist in the development of new drugs against SARS-CoV-2.

Design and functional validation of a chimeric E3 ubiquitin ligase targeting the spike protein S1 subunit of SARS-CoV-2

The spike (S) protein plays a crucial role in the entry of SARS-CoV-2 into host cells. The S protein contains two subunits, S1 and S2. The receptor-binding domain (RBD) of the S1 subunit binds to the receptor angiotensin-converting enzyme 2 (ACE2) to enter the host cells. Therefore, degrading S1 is one of the feasible strategies to inhibit SARS-CoV-2 infection. The purpose of this study is to develop a degradation tool targeting S1. First, we constructed a HEK 293 cell line stably expressing S1 by using a three-plasmid lentivirus system. The overexpression of the mitochondrial E3 ubiquitin protein ligase 1 (MUL1) in this cell line promoted the ubiquitination of S1 and accelerated its proteasomal degradation. Further research showed the polyubiquitination of S1 catalyzed by MUL1 mainly occurred via the addition of K48-linked chains. Moreover, the specific peptide LCB1, which targets and recognizes S1, was combined with MUL1 to create the chimeric E3 ubiquitin ligase LCB1-MUL1. In comparison to MUL1, this chimeric enzyme demonstrated improved catalytic efficiency, resulting in a reduction of S1's half-life from 12 h to 9 h. In summary, this study elucidated the mechanism by which MUL1 promotes the ubiquitination modification of S1 and facilitates its degradation through the proteasome, and preliminarily validated the effectiveness of targeted degradation of S1 by chimeric enzyme LCB1-MUL1.

Effect of carbon black and silicon dioxide nanoparticle exposure on corona receptor ACE2 and TMPRSS2 expression in the ocular surface

The Coronavirus disease 2019 (COVID-19) pandemic has led to a global health crisis, including ocular symptoms, primarily targeting the Angiotensin-Converting Enzyme 2 (ACE2) receptor. PM2.5 air pollution may increase infection risk by altering ACE2 expression. Silicon Dioxide (SiO2) and carbon black (CB), major components of PM2.5 from sands and vehicle emissions, were studied for their effects on ACE2 and Transmembrane Protease Serine 2 (TMPRSS2) expression in corneal and conjunctival cells, and ocular tissues. Human corneal epithelial cells (HCECs) and conjunctival epithelial cells (HCjECs) were exposed to nanoparticles (NPs) for 24 hours, assessing viability via WST-8 assay. TNF-α, IL-6, and IL-1β levels in the medium were measured. An in vivo rat study administered NPs via eye drops, with Rose Bengal staining to evaluate damage. ACE2, TMPRSS2, and Angiotensin II (AngII) protein expressions were quantified by Western blot. ACE2 expression in HCjECs increased with NP exposure, while it decreased in HCECs. CB exposure increased TNF-α, IL-6, and IL-1β levels in HCECs. In vivo, corneal exposure to CB decreased ACE2 expression, whereas conjunctival exposure to SiO2 increased ACE2 expression. These changes suggest that SiO2 exposure may increase the risk of COVID-19 through the ocular surface, while CB exposure may decrease it.

Molecular characteristics of organic matters in PM2.5 associated with upregulation of respiratory virus infection in vitro

The extent to which organic matters (OM) in PM2.5 affect virus infections and the key organic molecules involved in this process remain unclear. Herein, this study utilized ultra-high resolution mass spectrometry coupled with in vitro experiments to identify the organic molecules associated with respiratory virus infection for the first time. Water-soluble organic matters (WSOM) and water-insoluble organic matters (WIOM) were separated from PM2.5 samples collected at the urban area of Guangzhou, China. Their molecular compositions were analyzed using Fourier transform ion cyclotron resonance mass spectrometry. Subsequently, in vitro experiments were conducted to explore the impact of WSOM and WIOM exposure on the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pseudo-virus infection in A549 cells. Results revealed that WSOM and WIOM respectively promoted 1.7 to 2.1-fold and 1.9 to 3.5-fold upregulation of SARS-CoV-2 pseudo-virus infection in a concentration-dependent manner (at 25 to 100 μg mL−1) compared to the virus-only control group. Partial least squares model analysis indicated that the increased virus infection was likely related to phthalate ester and nitro-aromatic molecules in WSOM, as well as LipidC molecules with aliphatic and olefinic structures in WIOM. Interestingly, the molecules responsible for upregulating SARS-CoV-2 receptor angiotensin-converting enzyme 2 (ACE2) expression and virus infection differed. Thus, it was concluded that ACE2 upregulation alone may not fully elucidate the mechanisms underlying increased susceptibility to virus infection. The findings highlight the critical importance of aromatic and lipid molecules found in OM in relation to respiratory virus infection.

Fullerenol C60(OH)40 Nanoparticles and Ectoine Protect Human Nasal Epithelial Cells Against the Cytokine Storm After Addition of the Full-Length Spike Protein from SARS-CoV-2.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) enters the nasal cavity, penetrates the nasal epithelial cells through the interaction of its spike protein with the host cell receptor angiotensin-converting enzyme 2 (ACE2) and then triggers a cytokine storm. We aimed to assess the biocompatibility of fullerenol nanoparticles C60(OH)40 and ectoine, and to document their effect on the protection of primary human nasal epithelial cells (HNEpCs) against the effects of interaction with the fragment of virus - spike protein. This preliminary research is the first step towards the construction of a intranasal medical device with a protective, mechanical function against SARS-CoV-2 similar to that of personal protective equipment (eg masks). We used HNEpCs and the full-length spike protein from SARS-CoV-2 to mimic the first stage of virus infection. We assessed cell viability with the XTT assay and a spectrophotometer. May-Grünwald Giemsa and periodic acid-Schiff staining served to evaluate HNEpC morphology. We assessed reactive oxygen species (ROS) production by using 2',7'-dichlorofluorescin diacetate and commercial kit. Finally, we employed reverse transcription polymerase chain reaction, Western blotting and confocal microscopy to determine the expression of angiotensin-converting enzyme 2 (ACE2) and inflammatory cytokines. There was normal morphology and unchanged viability of HNEpCs after incubation with 10 mg/L C60(OH)40, 0.2% ectoine or their composite for 24h. The spike protein exerted cytotoxicity via ROS production. Preincubation with the composite protected HNEpCs against the interaction between the spike protein and the host membrane and prevented the production of key cytokines characteristic of severe coronavirus disease 2019, including interleukin 6 and 8, monocyte chemotactic protein 1 and 2, tissue inhibitor of metalloproteinases 2 and macrophage colony-stimulating factor. In the future, the combination of fullerenol and ectoine may be used to prevent viral infections as an intranasal medical device for people with reduced immunity and damaged mucous membrane.

Facilitating and restraining virus infection using cell-attachable soluble viral receptors

SARS-CoV-2 uses the receptor binding domain (RBD) of its spike protein to recognize and infect host cells by binding to the cell surface receptor angiotensin converting enzyme 2 (ACE2). The ACE2 receptor is composed of peptidase domain (PD), collectrin-like domain, transmembrane domain, and short cytoplasmic domain, and may exist as a dimer on cell surface. The RBD binding site is located atop of the ACE2 PD, but the involvement of other domains in virus infection is uncertain. We found that the ACE2 PD alone, whether anchored to cell membrane via a glycosylphosphatidylinositol anchor or attached to another surface protein, is fully functional as a receptor for spike-mediated cell fusion and virus infection. However, for ACE2 to function as the viral receptor, the RBD binding site must be positioned in close proximity to the cell membrane. Elevating the surface height of ACE2 using long and rigid protein spacers reduces or eliminates cell fusion and virus infection. Moreover, we found that the RBD-targeting neutralizing antibodies, nanobodies, and de novo designed miniprotein binders, when present on cell surface, also act as viral receptors, facilitating cell fusion and virus infection. Our data demonstrate that RBD binding and close membrane proximity are essential properties for a receptor to effectively mediate SARS-CoV-2 infection. Importantly, we show that soluble RBD-binders can be engineered to make cells either susceptible or resistant to virus infection, which has significant implications for antiviral therapy and various virus-mediated applications.

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.

Unveiling the Interplay-Vitamin D and ACE-2 Molecular Interactions in Mitigating Complications and Deaths from SARS-CoV-2.

The interaction of the SARS-CoV-2 spike protein with membrane-bound angiotensin-converting enzyme-2 (ACE-2) receptors in epithelial cells facilitates viral entry into human cells. Despite this, ACE-2 exerts significant protective effects against coronaviruses by neutralizing viruses in circulation and mitigating inflammation. While SARS-CoV-2 reduces ACE-2 expression, vitamin D increases it, counteracting the virus's harmful effects. Vitamin D's beneficial actions are mediated through complex molecular mechanisms involving innate and adaptive immune systems. Meanwhile, vitamin D status [25(OH)D concentration] is inversely correlated with severity, complications, and mortality rates from COVID-19. This study explores mechanisms through which vitamin D inhibits SARS-CoV-2 replication, including the suppression of transcription enzymes, reduced inflammation and oxidative stress, and increased expression of neutralizing antibodies and antimicrobial peptides. Both hypovitaminosis D and SARS-CoV-2 elevate renin levels, the rate-limiting step in the renin-angiotensin-aldosterone system (RAS); it increases ACE-1 but reduces ACE-2 expression. This imbalance leads to elevated levels of the pro-inflammatory, pro-coagulatory, and vasoconstricting peptide angiotensin-II (Ang-II), leading to widespread inflammation. It also causes increased membrane permeability, allowing fluid and viruses to infiltrate soft tissues, lungs, and the vascular system. In contrast, sufficient vitamin D levels suppress renin expression, reducing RAS activity, lowering ACE-1, and increasing ACE-2 levels. ACE-2 cleaves Ang-II to generate Ang(1-7), a vasodilatory, anti-inflammatory, and anti-thrombotic peptide that mitigates oxidative stress and counteracts the harmful effects of SARS-CoV-2. Excess ACE-2 molecules spill into the bloodstream as soluble receptors, neutralizing and facilitating the destruction of the virus. These combined mechanisms reduce viral replication, load, and spread. Hence, vitamin D facilitates rapid recovery and minimizes transmission to others. Overall, vitamin D enhances the immune response and counteracts the pathological effects of SARS-CoV-2. Additionally, data suggests that widely used anti-hypertensive agents-angiotensin receptor blockers and ACE inhibitors-may lessen the adverse impacts of SARS-CoV-2, although they are less potent than vitamin D.