Pericytes may facilitate SARS-CoV-2 entry into the nervous system

Objective: Although the neurological and olfactory symptoms of coronavirus disease 2019 have been identified, the neurotropic properties of the causative virus, severe acute respiratory syndrome-associated coronavirus 2 (SARS-CoV-2), remain unknown. We sought to identify the susceptible cell types and potential routes of SARS-CoV-2 entry into the central nervous system, olfactory system, and respiratory system. Method(s): We collected single-cell RNA data from normal brain and nasal epithelium specimens, along with bronchial, tracheal, and lung specimens in public datasets. The susceptible cell types that express SARS-CoV-2 entry genes were identified using single-cell RNA sequencing and the expression of the key genes at protein levels was verified by immunohistochemistry. We compared the coexpression patterns of the entry receptor angiotensin-converting enzyme 2 (ACE2) and the spike protein priming enzyme transmembrane serine protease (TMPRSS)/cathepsin L among the specimens. Result(s): The SARS-CoV-2 entry receptor ACE2 and the spike protein priming enzyme TMPRSS/cathepsin L were coexpressed by pericytes in brain tissue;this coexpression was confirmed by immunohistochemistry. In the nasal epithelium, ciliated cells and sustentacular cells exhibited strong coexpression of ACE2 and TMPRSS. Neurons and glia in the brain and nasal epithelium did not exhibit coexpression of ACE2 and TMPRSS. However, coexpression was present in ciliated cells, vascular smooth muscle cells, and fibroblasts in tracheal tissue;ciliated cells and goblet cells in bronchial tissue;and alveolar epithelium type 1 cells, AT2 cells, and ciliated cells in lung tissue. Conclusion(s): Neurological symptoms in patients with coronavirus disease 2019 could be associated with SARS-CoV-2 invasion across the blood-brain barrier via pericytes. Additionally, SARS-CoV-2-induced olfactory disorders could be the result of localized cell damage in the nasal epithelium.Copyright © Wolters Kluwer Health, Inc. All rights reserved.

SARS-CoV-2 Omicron Specific Mutations Affecting Infectivity, Fusogenicity, and Partial TMPRSS2-Independency.

The COVID-19 pandemic resulted from the global spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Since its first appearance in 2019, new SARS-CoV-2 variants of concern (VOCs) have emerged frequently, changing the infection's dynamic. SARS-CoV-2 infects cells via two distinct entry routes; receptor-mediated endocytosis or membrane fusion, depending on the absence or presence of transmembrane serine protease 2 (TMPRSS2), respectively. In laboratory conditions, the Omicron SARS-CoV-2 strain inefficiently infects cells predominantly via endocytosis and is phenotypically characterized by decreased syncytia formation compared to the earlier Delta variant. Thus, it is important to characterize Omicron's unique mutations and their phenotypic manifestations. Here, by utilizing SARS-CoV-2 pseudovirions, we report that the specific Omicron Spike F375 residue decreases infectivity, and its conversion to the Delta S375 sequence significantly increases Omicron infectivity. Further, we identified that residue Y655 decreases Omicron's TMPRSS2 dependency and entry via membrane fusion. The Y655H, K764N, K856N and K969N Omicron revertant mutations, bearing the Delta variant sequence, increased the cytopathic effect of cell-cell fusion, suggesting these Omicron-specific residues reduced the severity of SARS-CoV-2. This study of the correlation of the mutational profile with the phenotypic outcome should sensitize our alertness towards emerging VOCs.

Withania somnifera phytochemicals possess SARS-CoV-2 RdRp and human TMPRSS2 protein binding potential.

Abstract: Coronavirus disease-19 (COVID-19) pandemic caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) has infected approximately 26 million people and caused more than 6 million deaths globally. Spike (S)-protein on the outer surface of the virus uses human trans-membrane serine protease-2 (TMPRSS2) to gain entry into the cell. Recent reports indicate that human dipeptidyl peptidase-4 inhibitors (DPP4 or CD26) could also be utilized to check the S-protein mediated viral entry into COVID-19 patients. RNA dependent RNA polymerase (RdRp) is another key virulence protein of SARS-CoV-2 life cycle. The study aimed to identify the potential anti-SARS-CoV-2 inhibitors present in Withania somnifera (Solanaceae) using computer aided drug discovery approach. Molecular docking results showed that flavone glycoside, sugar alcohol, and flavonoid present in W. somnifera showed - 11.69, - 11.61, - 10.1, - 7.71 kcal/mole binding potential against S-protein, CD26, RdRp, and TMPRSS2 proteins. The major standard inhibitors of the targeted proteins (Sitagliptin, VE607, Camostat mesylate, and Remdesivir) showed the - 7.181, - 6.6, - 5.146, and - 7.56 kcal/mole binding potential. Furthermore, the lead phytochemicals and standard inhibitors bound and non-bound RdRp and TMPRSS2 proteins were subjected to molecular dynamics (MD) simulation to study the complex stability and change in protein conformation. The result showed energetically favorable and stable complex formation in terms of RMSD, RMSF, SASA, Rg, and hydrogen bond formation. Drug likeness and physiochemical properties of the test compounds exhibited satisfactory results. Taken together, the present study suggests the presence of potential anti-SARS-CoV-2 phytochemicals in W. somnifera that requires further validation in in vitro and in vivo studies. Supplementary information: The online version contains supplementary material available at 10.1007/s42535-022-00404-4.

Analyzing the role of ACE2, AR, MX1 and TMPRSS2 genetic markers for COVID-19 severity.

BACKGROUND: The use of molecular biomarkers for COVID-19 remains unconclusive. The application of a molecular biomarker in combination with clinical ones that could help classifying aggressive patients in first steps of the disease could help clinician and sanitary system a better management of the disease. Here we characterize the role of ACE2, AR, MX1, ERG, ETV5 and TMPRSS2 for trying a better classification of COVID-19 through knowledge of the disease mechanisms. METHODS: A total of 329 blood samples were genotyped in ACE2, MX1 and TMPRSS2. RNA analyses were also performed from 258 available samples using quantitative polymerase chain reaction for genes: ERG, ETV5, AR, MX1, ACE2, and TMPRSS2. Moreover, in silico analysis variant effect predictor, ClinVar, IPA, DAVID, GTEx, STRING and miRDB database was also performed. Clinical and demographic data were recruited from all participants following WHO classification criteria. RESULTS: We confirm the use of ferritin (p < 0.001), D-dimer (p < 0.010), CRP (p < 0.001) and LDH (p < 0.001) as markers for distinguishing mild and severe cohorts. Expression studies showed that MX1 and AR are significantly higher expressed in mild vs severe patients (p < 0.05). ACE2 and TMPRSS2 are involved in the same molecular process of membrane fusion (p = 4.4 × 10-3), acting as proteases (p = 0.047). CONCLUSIONS: In addition to the key role of TMPSRSS2, we reported for the first time that higher expression levels of AR are related with a decreased risk of severe COVID-19 disease in females. Moreover, functional analysis demonstrates that ACE2, MX1 and TMPRSS2 are relevant markers in this disease.

ACE-2, TMPRSS2, and Neuropilin-1 Receptor Expression on Human Brain Astrocytes and Pericytes and SARS-CoV-2 Infection Kinetics.

Angiotensin Converting Enzyme 2 (ACE-2), Transmembrane Serine Protease 2 (TMPRSS-2) and Neuropilin-1 cellular receptors support the entry of SARS-CoV-2 into susceptible human target cells and are characterized at the molecular level. Some evidence on the expression of entry receptors at mRNA and protein levels in brain cells is available, but co-expression of these receptors and confirmatory evidence on brain cells is lacking. SARS-CoV-2 infects some brain cell types, but infection susceptibility, multiple entry receptor density, and infection kinetics are rarely reported in specific brain cell types. Highly sensitive Taqman ddPCR, flow-cytometry and immunocytochemistry assays were used to quantitate the expression of ACE-2, TMPRSS-2 and Neuropilin-1 at mRNA and protein levels on human brain-extracted pericytes and astrocytes, which are an integral part of the Blood-Brain-Barrier (BBB). Astrocytes showed moderate ACE-2 (15.9 ± 1.3%, Mean ± SD, n = 2) and TMPRSS-2 (17.6%) positive cells, and in contrast show high Neuropilin-1 (56.4 ± 39.8%, n = 4) protein expression. Whereas pericytes showed variable ACE-2 (23.1 ± 20.7%, n = 2), Neuropilin-1 (30.3 ± 7.5%, n = 4) protein expression and higher TMPRSS-2 mRNA (667.2 ± 232.3, n = 3) expression. Co-expression of multiple entry receptors on astrocytes and pericytes allows entry of SARS-CoV-2 and progression of infection. Astrocytes showed roughly four-fold more virus in culture supernatants than pericytes. SARS-CoV-2 cellular entry receptor expression and "in vitro" viral kinetics in astrocytes and pericytes may improve our understanding of viral infection "in vivo". In addition, this study may facilitate the development of novel strategies to counter the effects of SARS-CoV-2 and inhibit viral infection in brain tissues to prevent the spread and interference in neuronal functions.

Genetic Variants within SARS-CoV-2 Human Receptor Genes May Contribute to Variable Disease Outcomes in Different Ethnicities.

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has evolved into a global pandemic, with an alarming infectivity and mortality rate. Studies have examined genetic effects on SARS-CoV-2 disease susceptibility and severity within Eurasian populations. These studies identified contrasting effects on the severity of disease between African populations. Genetic factors can explain some of the diversity observed within SARS-CoV-2 disease susceptibility and severity. Single nucleotide polymorphisms (SNPs) within the SARS-CoV-2 receptor genes have demonstrated detrimental and protective effects across ethnic groups. For example, the TT genotype of rs2285666 (Angiotensin-converting enzyme 2 (ACE2)) is associated with the severity of SARS-CoV-2 disease, which is found at higher frequency within Asian individuals compared to African and European individuals. In this study, we examined four SARS-CoV-2 receptors, ACE2, Transmembrane serine protease 2 (TMPRSS2), Neuropilin-1 (NRP1), and Basigin (CD147). A total of 42 SNPs located within the four receptors were reviewed: ACE2 (12), TMPRSS2 (10), BSG (CD147) (5), and NRP1 (15). These SNPs may be determining factors for the decreased disease severity observed within African individuals. Furthermore, we highlight the absence of genetic studies within the African population and emphasize the importance of further research. This review provides a comprehensive summary of specific variants within the SARS-CoV-2 receptor genes, which can offer a better understanding of the pathology of the SARS-CoV-2 pandemic and identify novel potential therapeutic targets.

REMDESIVIR RETAINS POTENT ACTIVITY AGAINST SARS-CoV-2 VARIANTS OF CONCERN

Background: Recent SARS-CoV-2 variants of concern (VOCs) have shown a progressive loss of sensitivity to monoclonal antibody therapeutics. Remdesivir (RDV) is a nucleotide analog prodrug that targets the viral RNA-dependent RNA polymerase (RdRp) Nsp12 and is approved to treat COVID-19 in hospitalized and non-hospitalized patients. Nsp12 is highly conserved across VOCs to date and RDV antiviral activity against previous VOCs (Alpha to Omicron BA.1) has been maintained. Here, we conduct a structural analysis of Nsp12 substitutions observed in recent Omicron subvariants (BA.2, BA.2.12.1, BA.4, BA.5 and BA.2.75) and assess RDV antiviral activity against clinical isolates and sitedirected mutants (SDMs) in a replicon system. Method(s): The prevalence of Nsp12 substitutions in Omicron subvariants was evaluated by analysis of sequences from the Global Initiative on Sharing Avian Influenza Data (GISAID) EpiCoV database. Structural analysis of identified substitutions was conducted on a prior cryo-electron microscopy-based model of the replication-transcription complex. Antiviral activity against subvariant clinical isolates was assessed by nucleoprotein ELISA in A549-hACE2-TMPRSS2 cells and by SDMs in the replicon system. Result(s): Genomic analysis of >1.4 million Omicron subvariant sequences revealed unique substitutions in Nsp12 compared to the ancestral WA1 strain. Besides P323L, present in all subvariants, G671S was observed in 95.9% of BA.2.75 sequences, F694Y was observed in <=1.9% of BA.4, BA.5 and BA.2.75 sequences, and Y521C was observed in 1.7% of BA.5 sequences. As anticipated, structural analysis of these substitutions showed no direct interaction with the incoming RDV nucleotide triphosphate or the viral RNA. Phenotyping of clinical isolates of Omicron subvariants BA.2, BA.2.12.1, BA.4, BA.5, and BA.2.75 consistently resulted in mean RDV EC50 values of 24.5 nM (BA.2) to 106.0 nM (BA.5). This represented 0.15-to 0.66-fold changes compared to WA1, indicating no loss of in vitro RDV antiviral activity against these VOCs. P323L, G671S, and F694Y were shown previously to have no impact on RDV antiviral activity. Similarly, the individual substitution Y521C showed no change in RDV susceptibility in the SARS-CoV-2 replicon system. Conclusion(s): RDV retained potent in vitro antiviral activity against all tested Omicron VOCs with potencies comparable to the WA1 isolate. These data support the continued use of RDV in patients infected with Omicron subvariants.

Towards Neuro-CoViD-19.

CoViD-19 is the current pandemic caused by the Severe Acute Respiratory Syndrome Corona Virus-2 (SARS-CoV-2). Infection by SARS-CoV-2 occurs via the binding of its S protein to the angiotensin-converting enzyme-2 receptor (ACE2-R). S binding to ACE2-R leads to a drop in ACE2, a homolog of angiotensin converting enzyme (ACE). In the central nervous system (CNS), ACE mediates neuroinflammation, neurodegeneration and neurotoxicity responsible for several CNS disorders. ACE2 counteracts the damaging effects of ACE on CNS neurons. SARS-CoV-2 can directly access the CNS via the circulation or via cranial nerve I and the olfactory bulb. Inactivation of ACE2 following binding of SARS-CoV-2 S protein to ACE2-R in situ might blunt ACE2-moderating effects upon ACE CNS neurotoxicity and neurodegeneration. Here, we propose a neurobiological mechanism directly involving SARS-CoV-2 binding to ACE2-R in the etiology of putative Neuro-CoViD-19.

ACE2 Receptor and TMPRSS2 Protein Expression Patterns in the Human Brainstem Reveal Anatomical Regions Potentially Vulnerable to SARS-CoV-2 Infection.

Angiotensin-converting enzyme 2 receptor (ACE2R) is a transmembrane protein expressed in various tissues throughout the body that plays a key role in the regulation of blood pressure. Recently, ACE2R has gained significant attention due to its involvement in the pathogenesis of COVID-19, the disease caused by the Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2). While ACE2 receptors serve as entry points for the novel coronavirus, Transmembrane Serine Protease 2 (TMPRSS2), an enzyme located on the cell membrane, is required for SARS-CoV-2 S protein priming. Even though numerous studies have assessed the effects of COVID-19 on the brain, very little information is available concerning the distribution of ACE2R and TMPRSS2 in the human brain, with particular regard to their topographical expression in the brainstem. In this study, we investigated the expression of ACE2R and TMPRSS2 in the brainstem of 18 adult subjects who died due to pneumonia/respiratory insufficiency. Our findings indicate that ACE2R and TMPRSS2 are expressed in neuronal and glial cells of the brainstem, particularly at the level of the vagal nuclei of the medulla and the midbrain tegmentum, thus confirming the expression and anatomical localization of these proteins within specific human brainstem nuclei. Furthermore, our findings help to define anatomically susceptible regions to SARS-CoV-2 infection in the brainstem, advancing knowledge on the neuropathological underpinnings of neurological manifestations in COVID-19.

Identification of potential Indonesian marine invertebrate bioactive compounds as TMPRSS2 and SARS-CoV-2 Omicron spike protein inhibitors through computational screening.

The coronavirus pandemic led to the announcement of a worldwide health emergency. The SARS-CoV-2 Omicron variant, which swiftly spread worldwide, has fueled existing challenges. Appropriate medication is necessary to avoid severe SARS-CoV-2 disease. The human TMPRSS2 and SARS-CoV-2 Omicron spike protein, which are required for viral entry into the host phase, were identified as the target proteins through computational screening. Structure-based virtual screening; molecular docking; absorption, distribution, metabolism, excretion, and toxicity (ADMET) analysis; and molecular dynamics simulation were the methods applied for TMPRSS2 and spike protein inhibitors. Bioactive marine invertebrates from Indonesia were employed as test ligands. Camostat and nafamostat (co-crystal) were utilized as reference ligands against TMPRSS2, whereas mefloquine was used as a reference ligand against spike protein. Following a molecular docking and dynamics simulation, we found that acanthomanzamine C has remarkable effectiveness against TMPRSS2 and spike protein. Compared to camostat (-8.25 kcal/mol), nafamostat (-6.52 kcal/mol), and mefloquine (-6.34 kcal/mol), acanthomanzamine C binds to TMPRSS2 and spike protein with binding energies of -9.75 kcal/mol and -9.19 kcal/mol, respectively. Furthermore, slight variances in the MD simulation demonstrated consistent binding to TMPRSS2 and spike protein after the initial 50 ns. These results are highly valuable in the search for a treatment for SARS-CoV-2 infection.

Association between tissue stress reaction and ACE2/TMPRSS2 expression in endometria of reproductive aged women before and during Covid-19 pandemic.

BACKGROUND: A potential concern has been raised regarding fertility and reproductive outcome during the Covid-19 pandemic with growing stress and anxiety. However, information on the association between tissue stress reaction and expression profiles of SARS-CoV-2 viral entry proteins, ACE2 and TMPRSS2, in endometria collected from women before (pre-pandemic) and during the Covid-19 pandemic (in-pandemic) is unknown. We aim to investigate the relationship between the expression of stress-reactive proteins and of ACE2 and TMPRSS2 in endometria collected from women during these two different time frames. METHODS: We retrospectively retrieved tissue blocks of endometrial samples from 25 women in 2019 (pre-pandemic) and 25 women in 2020 (in-pandemic) who underwent hysterectomy for different gynecological indications. Immunohistochemical analysis was performed with endometrial tissue samples that were collected before and during the pandemic, using respective antibodies targeting ACE2/TMPRSS2, ADRB2 and NK1R (stress and anxiety receptor markers, respectively). The quantification of immunoreactive cells for each marker was calculated by the immunoreactive score (IRS) analysis. This retrospective cohort study was limited to small sample size. RESULTS: No significant differences in the IRS of ACE2 and TMPRSS2 were found between the endometria that were collected before and during the pandemic with a lack of correlation between ACE2 and TMPRSS2 expression in respective endometria (r = 0.11, pre-pandemic; r = 0.04, in-pandemic). The immunostaining levels of stress marker, ADRB2 were significantly higher in the endometria of in-pandemic group (p = 0.015) comparing to that of pre-pandemic group. Pearson's correlation coefficient analysis showed a significant correlation in the expression between ADRB2 and TMPRSS2 (r = 0.41, p = 0.042) in the endometria of in-pandemic group but not in the pre-pandemic group. CONCLUSION: The rise in stress and anxiety among women during current pandemic may elicit substantial amount of tissue stress reaction with consequent increase in the expression of SARS-CoV-2 viral entry proteins in their endometria. A lack of correlation between ACE2 and TMPRSS2 expression in endometria may reassure women in their reproductive age that they are not more susceptible to infection by SARS-CoV-2 and suggest that stressful women during this pandemic can safely decide to conceive naturally or by artificial reproductive technology.

Virtual Screening for Sars-Cov-2 Entry Inhibitors by Dual Targeting of Tmprss2 and Ctsl

The COVID-19 pandemic remains to be a global public health crisis due to the emergence of new variants of concern and the scarcity of drug treatments. The cell entry of SARS-CoV-2 requires activation of its spike protein by host proteases TMPRSS2 and CTSL, which triggers membrane fusion and facilitates the endocytic uptake mechanism, respectively. This study employed a structure-based virtual screening technique to identify drugs and natural products that simultaneously target TMPRSS2 and CTSL. Two pharmacophore models were generated from the binding sites of the proteins in complex with their co-crystallized ligands. Both structure-based pharmacophores were used to screen a ligand library composed of 41,775 compounds (10,849 drugs from the ChEMBL database and 30,926 natural products from the NPASS database). A total of 115 compounds (54 drugs and 61 natural products) that fit both TMPRSS2 and CTSL pharmacophore models were identified. The common hits were docked into both proteases to obtain a short list of compounds. Molecular docking filtered 17 compounds (5 drugs and 12 natural products) that have higher binding energy values than the co-crystallized ligands and known inhibitors of both proteins. The top hits were then subjected to ADMET, drug-likeness, and synthetic accessibility filters. Based on docking scores, pharmacokinetics, and drug-likeness, Silibinin was the most promising repurposed drug candidate as a treatment for SARS-CoV-2 infection via dual inhibition of TMPRSS2 and CTSL. Among the natural products, barettin was the best candidate for further development as a novel dual TMPRSS2 and CTSL inhibitor.

Prostate-specific antigen level association with COVID-19 infection and vaccination.

INTRODUCTION: The associations among SARS-CoV-2 infection, vaccination and total serum prostate serum antigen (PSA) levels in men undergoing screening for prostate cancer are unknown. METHODS: A retrospective analysis of data from a large health maintenance organization. Records of individuals aged 50 to 75 years with two serum PSA tests taken between March 2018 and November 2021 were included. Individuals with prostate cancer were excluded. Changes in PSA levels were compared between individuals who had at least 1 SARS-CoV-2 vaccination and/or infection between the two PSA tests and individuals who did not have an infection and were not vaccinated between the two PSA tests. Subgroup analyses were performed to assess the impact of the elapsed time between the event and the second PSA test on the results. RESULTS: The study and control groups included 6,733 (29%) and 16 286 (71%) individuals, respectively. Although the median time between PSA tests was shorter in the study vs. the control group (440 vs. 469 days, P<.001), PSA elevation between the tests was higher in the study group (0.04 vs. 0.02, P<.001). The relative risk for PSA elevation ≥1 ng/dL was 1.22 (95% CI 1.1, 1.35). Among individuals who were vaccinated, PSA increased by 0.03 ng/dL (IQR -0.12, 0.28) and 0.09 ng/dL (IQR -0.05, 0.34) after 1 and 3 doses, respectively (P<.001). Multivariate linear regression showed that SARS-CoV-2 events (ß 0.043; 95% CI 0.026-0.06) were associated with a greater risk for PSA elevation, after adjusting for age, baseline PSA and days between PSA tests. CONCLUSION: SARS-CoV-2 infection and vaccinations are associated with a slight increase in PSA, with the third anti-COVID vaccine dose having a more prominent impact, but its clinical significance is unknown yet. Any significant increase in PSA must be investigated and cannot be dismissed as secondary to SARS-CoV-2 infection or vaccination.

Mpro Inhibition: A comparative In silico Therapeutics from Native Indian Plant Species

One of the biggest healthcare threats of this century is COVID – 19, undoubtedly. It has caused millions of deaths and raised alerts in the healthcare domain. This study focuses on the importance of 10 native Indian plant species and the phytochemicals obtained from them as a potential inhibitor to the Main protease enzyme of SARS CoV-2. About 26 phytochemicals were shortlisted for the same from the selected plants. Molecular docking was used to analyze the binding affinity of the phytochemicals in the active pocket of the Main protease enzyme to assess their effectiveness. The docking scores resulted in the selection of four compounds being more favorable than the native inhibitor N3, namely Quercetin, Withaferin A, Sominone, and Nimbin, with their binding energies being-8.42,-9.21,-9.95,-8.88 kcal/mol respectively. Furthermore, these four were further analyzed for their bioavailability scores. The studies showed that Sominone, Withaferin A are more potent inhibitors to Mpro of the SARS CoV-2 in all four. Thus further in Vitro studies can be done accordingly for the same. © 2022 by the authors.

Harnessing and bioprospecting botanical-based herbal medicines against potential drug targets for COVID-19: a review coupled molecular docking studies.

Since the end of February 2020, the world has come to a standstill due to the virus SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2). Since then, the global scientific community has explored various remedies and treatments against this virus, including natural products that have always been a choice because of their many benefits. Various known phytochemicals are well documented for their antiviral properties. Research is being carried out to discover new natural plant products or existing ones as a treatment measure for this disease. The three important targets in this regard are-papain like protease (PLpro), spike protein, and 3 chymotrypsin like proteases (3CLpro). Various docking studies are also being elucidated to identify the phytochemicals that modulate crucial proteins of the virus. The paper is simultaneously a comprehensive review that covers recent advances in the domain of the effect of various botanically derived natural products as an alternative treatment approach against Coronavirus Disease 2019 (COVID-19). Furthermore, the docking analyses revealed that rutin (inhibitor of the major protease of SARS-CoV-2), gallocatechin (e.g., interacting with 03 hydrogen bonds with a spike-like protein), lycorine (showing the best binding affinity with amino acids GLN498, THR500 and GLY446 of the spike-like protein), and quercetrin (inhabiting at its residues ASP216, PHE219, and ILE259) are promising inhibitors of SARS­CoV­2.Communicated by Ramaswamy H. Sarma.

SARS-CoV-2 Enters Human Leydig Cells and Affects Testosterone Production In Vitro.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a SARS-like coronavirus, continues to produce mounting infections and fatalities all over the world. Recent data point to SARS-CoV-2 viral infections in the human testis. As low testosterone levels are associated with SARS-CoV-2 viral infections in males and human Leydig cells are the main source of testosterone, we hypothesized that SARS-CoV-2 could infect human Leydig cells and impair their function. We successfully detected SARS-CoV-2 nucleocapsid in testicular Leydig cells of SARS-CoV-2-infected hamsters, providing evidence that Leydig cells can be infected with SARS-CoV-2. We then employed human Leydig-like cells (hLLCs) to show that the SARS-CoV-2 receptor angiotensin-converting enzyme 2 is highly expressed in hLLCs. Using a cell binding assay and a SARS-CoV-2 spike-pseudotyped viral vector (SARS-CoV-2 spike pseudovector), we showed that SARS-CoV-2 could enter hLLCs and increase testosterone production by hLLCs. We further combined the SARS-CoV-2 spike pseudovector system with pseudovector-based inhibition assays to show that SARS-CoV-2 enters hLLCs through pathways distinct from those of monkey kidney Vero E6 cells, a typical model used to study SARS-CoV-2 entry mechanisms. We finally revealed that neuropilin-1 and cathepsin B/L are expressed in hLLCs and human testes, raising the possibility that SARS-CoV-2 may enter hLLCs through these receptors or proteases. In conclusion, our study shows that SARS-CoV-2 can enter hLLCs through a distinct pathway and alter testosterone production.

Omicsynin B4 potently blocks coronavirus infection by inhibiting host proteases cathepsin L and TMPRSS2.

The emergence of SARS-CoV-2 variants represents a major threat to public health and requires identification of novel therapeutic agents to address the unmet medical needs. Small molecules impeding viral entry through inhibition of spike protein priming proteases could have potent antiviral effects against SARS-CoV-2 infection. Omicsynin B4, a pseudo-tetrapeptides identified from Streptomyces sp. 1647, has potent antiviral activity against influenza A viruses in our previous study. Here, we found omicsynin B4 exhibited broad-spectrum anti-coronavirus activity against HCoV-229E, HCoV-OC43 and SARS-CoV-2 prototype and its variants in multiple cell lines. Further investigations revealed omicsynin B4 blocked the viral entry and might be related to the inhibition of host proteases. SARS-CoV-2 spike protein mediated pseudovirus assay supported the inhibitory activity on viral entry of omicsynin B4 with a more potent inhibition of Omicron variant, especially when overexpression of human TMPRSS2. Moreover, omicsynin B4 exhibited superior inhibitory activity in the sub-nanomolar range against CTSL, and a sub-micromolar inhibition against TMPRSS2 in biochemical assays. The molecular docking analysis confirmed that omicsynin B4 fits well in the substrate binding sites and forms a covalent bond to Cys25 and Ser441 in CTSL and TMPRSS2, respectively. In conclusion, we found that omicsynin B4 may serve as a natural protease inhibitor for CTSL and TMPRSS2, blocking various coronavirus S protein-driven entry into cells. These results further highlight the potential of omicsynin B4 as an attractive candidate for broad-spectrum antiviral therapy that could rapidly respond to emerging variants of SARS-CoV-2.

A Review of Special Considerations on Insulin Resistance Induced Hyperandrogenemia in Women with Polycystic Ovary Syndrome: A Prominent COVID-19 Risk Factor.

Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) infecting mechanism depends on hosting angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2) as essential components and androgens as regulators for inducing the expression of these components. Therefore, hyperandrogenism-related disease such as polycystic ovary syndrome (PCOS) in insulin resistant women in reproductive-age is a high-risk factor for SARS-CoV-2 infection. Here, we describe the signaling pathways that might increase the susceptibility and severity of this new pandemic in PCOS women with insulin resistance (IR). Luteinizing hormone and insulin increase the risk of SARS-CoV-2 infection in these patients via the induction of steroidogenic enzymes expression through cAMP-response element binding protein and Forkhead box protein O1 (FOXO1), respectively. TMPRSS2 expression is activated through phosphorylation of FOXO1 in ovaries. In other words, SARS-CoV-2 infection is associated with temporary IR by affecting ACE2 and disturbing ß-pancreatic function. Therefore, PCOS, IR, and SARS-CoV-2 infection are three corners of the triangle that have complicated relations, and their association might increase the risk of SARS-CoV-2 infection and severity.

Receptors and Cofactors That Contribute to SARS-CoV-2 Entry: Can Skin Be an Alternative Route of Entry?

To prevent the spread of SARS-CoV-2, all routes of entry of the virus into the host must be mapped. The skin is in contact with the external environment and thus may be an alternative route of entry to transmission via the upper respiratory tract. SARS-CoV-2 cell entry is primarily dependent on ACE2 and the proteases TMPRSS2 or cathepsin L but other cofactors and attachment receptors have been identified that may play a more important role in specific tissues such as the skin. The continued emergence of new variants may also alter the tropism of the virus. In this review, we summarize current knowledge on these receptors and cofactors, their expression profile, factors modulating their expression and their role in facilitating SARS-CoV-2 infection. We discuss their expression in the skin and their possible involvement in percutaneous infection since the presence of the virus has been detected in the skin.

Would the Development of a Multitarget Inhibitor of 3CLpro and TMPRSS2 be Promising in the Fight Against SARS-CoV-2?

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV2), responsible for generating COVID-19, has spread worldwide and was declared a pandemic by the World Health Organization (WHO) on 11 March 2020, being responsible for various damages to public health, social life, and the economy of countries. Its high infectivity and mutation rates have stimulated researchers and pharmaceutical companies to search for new therapies against this disease. These efforts resulted in several vaccines and the identification of Molnupiravir as an oral treatment against this disease. However, identifying new alternatives and critical information is necessary to fight against this devastating agent. The findings in recent years regarding the structure and biochemistry of SARS-CoV2 are remarkable. In anti-CoV drug discovery, various targets such as structural, non-structural, and host-related proteins are explored. In fact, 3CLpro is the most used among non-structural proteins since this protease cleaves peptide sequences after the glutamine residue, and no human protease has this function. This makes this macromolecule an excellent drug target for discovering new compounds. Another promising target is the transmembrane protease serine 2 (TMPRSS2). Recent studies point to TMPRSS2 as one of the main targets responsible for viral entry, related to the cleavage of the S protein. Similar to cathepsins, TMPRSS2 is also responsible for cleaving the spike protein SARS-CoV2, which binds to the ACE2 receptor. Thus, TMPRSS2 is one of the targets that may represent new alternatives in treating SARS-CoV2. In this context, would discovering a multitarget inhibitor be the new strategy in searching for drugs against SARS-CoV2? For many years, new drug discovery was based on the "one drug, one target" premise, where the biological action is related to interactions with only one biological target. However, this paradigm has been overcome as new evidence of multiple mechanisms of action for a single drug. Finally, this review will present a perspective on drug design based on a multitarget strategy against 3CLpro and TMPRSS2. We hope to provide new horizons for researchers worldwide searching for more effective drugs against this devastating agent.