New insights into the pathogenesis of SARS-CoV-2 during and after the COVID-19 pandemic

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the respiratory distress condition known as COVID-19. This disease broadly affects several physiological systems, including the gastrointestinal, renal, and central nervous (CNS) systems, significantly influencing the patient's overall quality of life. Additionally, numerous risk factors have been suggested, including gender, body weight, age, metabolic status, renal health, preexisting cardiomyopathies, and inflammatory conditions. Despite advances in understanding the genome and pathophysiological ramifications of COVID-19, its precise origins remain elusive. SARS-CoV-2 interacts with a receptor-binding domain within angiotensin-converting enzyme 2 (ACE2). This receptor is expressed in various organs of different species, including humans, with different abundance. Although COVID-19 has multiorgan manifestations, the main pathologies occur in the lung, including pulmonary fibrosis, respiratory failure, pulmonary embolism, and secondary bacterial pneumonia. In the post-COVID-19 period, different sequelae may occur, which may have various causes, including the direct action of the virus, alteration of the immune response, and metabolic alterations during infection, among others. Recognizing the serious adverse health effects associated with COVID-19, it becomes imperative to comprehensively elucidate and discuss the existing evidence surrounding this viral infection, including those related to the pathophysiological effects of the disease and the subsequent consequences. This review aims to contribute to a comprehensive understanding of the impact of COVID-19 and its long-term effects on human health.

Serum AXL is a potential molecular marker for predicting COVID-19 progression

Background

The severity, symptoms, and outcome of COVID-19 is thought to be closely linked to how the virus enters host cells. This process involves the key roles of angiotensin-converting enzyme 2 (ACE2) and the Tyrosine protein kinase receptor UFO (AXL) receptors. However, there is limited research on the circulating levels of ACE2 and AXL and their implications in COVID-19.

Methods

A control group of 71 uninfected individuals was also included in the study. According to the Guidance for Corona Virus Disease 2019 (10th edition), a cohort of 358 COVID-19 patients were categorized into non-severe and severe cases. Serum ACE2/AXL levels in COVID-19 patients were detected by enzyme-linked immunosorbent assay (ELISA) at different time points post-COVID-19 infection, including days 0-7, 8-15, 31-179 and >180 days. Serum SARS-CoV-2 IgG/IgM antibodies in COVID-19 patients at the same intervals were assessed by using an iFlash 3000 Chemiluminescence Immunoassay Analyzer. The receiver operating characteristic (ROC) curves were used to assess the diagnostic value of the biological markers, and the association between laboratory parameters and illness progression were explored.

Results

Compared with the uninfected group, the levels of ACE2 and AXL in the COVID-19 group were decreased, and the SARS-COV-2 IgG level was increased. AXL (AUC = 0.774) demonstrated a stronger predictive ability for COVID-19 than ACE2. In the first week after infection, only the level of AXL was statistically different between severe group and non-severe group. After first week, the levels of ACE2 and AXL were different in two groups. Moreover, in severe COVID-19 cases, the serum ACE2, AXL, and SARS-COV-2 IgM levels reached a peak during days 8-15 before declining, whereas serum SARS-COV-2 IgG levels continued to rise, reaching a peak at day 31-180 days before decreasing. In addition, the AXL level continued to decrease and the SARS-COV-2 IgG level continued to increase in the infected group after 180 days compared to the uninfected group.

Conclusions

The levels of serum ACE2 and AXL correlate with COVID-19 severity. However, AXL can also provide early warning of clinical deterioration in the first week after infection. AXL appears to be a superior potential molecular marker for predicting COVID-19 progression.

Novel Omicron Variants Enhance Anchored Recognition of TMEM106B: A New Pathway for SARS-CoV-2 Cellular Invasion

The recent discovery that TMEM106B serves as a receptor mediating ACE2-independent SARS-CoV-2 entry into cells deserves attention, especially in the background of the frequent emergence of mutant strains. Here, the structure-dynamic features of this novel pathway are dissected deeply. Our investigation revealed that the large loop (RBD@471-491) could anchor TMEM106B, which was then firmly locked by another loop (RBD@444-451). The novel and widely disseminated Omicron variants (BA.2.86/EG.5.1) affect the anchoring recognition of proteins, with BA.2.86 being more likely to impact cells with limited or undetectable ACE2 expression. The large loop of the EG.5.1 variant captures TMEM106B poorly due to impaired electrostatic complementarity. Furthermore, we emphasize that antibody design against these two loops could enhance the protection of ACE2 low-expressing cells according to the alanine scanning mutagenesis of multiple antibodies. We hope this study will provide a novel perspective for the prevention and treatment against this new viral invasion pathway.

Proteomics-based mass spectrometry profiling of SARS-CoV-2 infection from human nasopharyngeal samples

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of the on-going global pandemic of coronavirus disease 2019 (COVID-19) that continues to pose a significant threat to public health worldwide. SARS-CoV-2 encodes four structural proteins namely membrane, nucleocapsid, spike, and envelope proteins that play essential roles in viral entry, fusion, and attachment to the host cell. Extensively glycosylated spike protein efficiently binds to the host angiotensin-converting enzyme 2 initiating viral entry and pathogenesis. Reverse transcriptase polymerase chain reaction on nasopharyngeal swab is the preferred method of sample collection and viral detection because it is a rapid, specific, and high-throughput technique. Alternate strategies such as proteomics and glycoproteomics-based mass spectrometry enable a more detailed and holistic view of the viral proteins and host-pathogen interactions and help in detection of potential disease markers. In this review, we highlight the use of mass spectrometry methods to profile the SARS-CoV-2 proteome from clinical nasopharyngeal swab samples. We also highlight the necessity for a comprehensive glycoproteomics mapping of SARS-CoV-2 from biological complex matrices to identify potential COVID-19 markers.

Heparin-Induced Allosteric Changes in SARS-CoV-2 Spike Protein Facilitate ACE2 Binding and Viral Entry

Understanding the entry of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) into host cells is crucial in the battle against COVID-19. Using atomic force microscopy (AFM), we probed the interaction between the virus's spike protein and heparan sulfate (HS) as a potential attachment factor. Our AFM studies revealed a moderate-affinity interaction between the spike protein and HS on both model surfaces and living cells, highlighting HS's role in early viral attachment. Remarkably, we observed an interplay between HS and the host cell receptor angiotensin-converting enzyme 2 (ACE2), with HS engagement resulting in enhanced ACE2 binding and subsequent viral entry. Our research furthers our understanding of SARS-CoV-2 infection mechanisms and reveals potential interventions targeting viral entry. These insights are valuable as we navigate the evolving landscape of viral threats and seek effective strategies to combat emerging infectious diseases.

Emerging Landscape of Preclinical Models for Studying COVID-19 Neurologic Diseases

COVID-19 (Coronavirus Disease 2019) is an infectious disease caused by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) and has globally infected 768 million people and caused over 6 million deaths. COVID-19 primarily affects the respiratory system but increasing reports of neurologic symptoms associated with COVID-19 have been reported in the literature. The exact mechanism behind COVID-19 neurologic pathophysiology remains poorly understood due to difficulty quantifying clinical neurologic symptoms in humans and correlating them to findings in human post-mortem samples and animal models. Thus, robust preclinical experimental models for COVID-19 neurologic manifestations are urgently needed. Here, we review recent advances in in vitro, in vivo, and other models and technologies for studying COVID-19 including primary cell cultures, pluripotent stem cell-derived neurons and organoids, rodents, nonhuman primates, 3D bioprinting, artificial intelligence, and multiomics. We specifically focus our discussion on the contribution, recent advancements, and limitations these preclinical models have on furthering our understanding of COVID-19's neuropathic physiology. We also discuss these models' roles in the screening and development of therapeutics, vaccines, antiviral drugs, and herbal medicine, and on future opportunities for COVID-19 neurologic research and clinical management.

Effect of prior female SARS-CoV-2 infection on IVF outcomes: a prospective cohort study

Introduction

The clinical impact of SARS-CoV-2 infection on human reproduction remains controversial. This prospective cohort study aimed to assess the effect of prior female SARS-CoV-2 infection on subsequent in vitro fertilization (IVF) outcomes.

Materials and methods

A total of 451 women who underwent fresh IVF treatment between December 1, 2022 and April 30, 2023 were included from an academic fertility center. Participants were divided into the infected group if they had a prior COVID-19 history before cycle initiation (n = 252), while the control group were those uninfected (n = 199). The primary outcomes were the number of oocytes retrieved and clinical pregnancy rate after fresh embryo transfer. Multivariate linear and logistic regression analyses were conducted to control for potential confounders.

Results

The number of oocytes retrieved (11.4 ± 8.3 vs. 11.6 ± 7.7; P = 0.457) and clinical pregnancy rate (70.3% vs. 73.7%; P = 0.590) were similar between infected and uninfected groups, with a fully adjusted β coefficient of 0 (95% confidence interval [CI]: -0.14-0.13) and odds ratio of 0.64 (95% CI: 0.20-2.07), respectively. Consistently, the two groups were comparable in cycle characteristics as well as other laboratory and pregnancy parameters. In both subgroup analyses and restricted cubic splines, different post-infection time intervals to IVF cycle initiation showed no significant associations with treatment outcomes.

Conclusion

Prior SARS-CoV-2 infection in females had no adverse influence on subsequent IVF treatment, regardless of the time interval following infection. Our findings provide reassurance for infected women planning for assisted reproduction. Additional prospective cohort studies with larger datasets and longer follow-up are required to confirm the conclusion.

Heart-on-a-chip model of immune-induced cardiac dysfunction reveals the role of free mitochondrial DNA and therapeutic effects of endothelial exosomes

Cardiovascular disease continues to take more human lives than all cancer combined, prompting the need for improved research models and treatment options. Despite a significant progress in development of mature heart-on-a-chip models of fibrosis and cardiomyopathies starting from induced pluripotent stem cells (iPSCs), human cell-based models of myocardial inflammation are lacking. Here, we bioengineered a vascularized heart-on-a-chip system with circulating immune cells to model SARS-CoV-2-induced acute myocarditis. Briefly, we observed hallmarks of COVID-19-induced myocardial inflammation in the heart-on-a-chip model, as the presence of immune cells augmented the expression levels of proinflammatory cytokines, triggered progressive impairment of contractile function and altered intracellular calcium transient activities. An elevation of circulating cell-free mitochondrial DNA (ccf-mtDNA) was measured first in the in vitro heart-on-a-chip model and then validated in COVID-19 patients with low left ventricular ejection fraction (LVEF), demonstrating that mitochondrial damage is an important pathophysiological hallmark of inflammation induced cardiac dysfunction. Leveraging this platform in the context of SARS-CoV-2 induced myocardial inflammation, we established that administration of human umbilical vein-derived EVs effectively rescued the contractile deficit, normalized intracellular calcium handling, elevated the contraction force and reduced the ccf- mtDNA and chemokine release via TLR-NF-kB signaling axis.

SARS-CoV-2 and male infertility: from short- to long-term impacts

PURPOSE

The coronavirus 2019 (COVID-19) pandemic-caused by a new type of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-has posed severe impacts on public health worldwide and has resulted in a total of > 6 million deaths. Notably, male patients developed more complications and had mortality rates ~ 77% higher than those of female patients. The extensive expression of the SARS-CoV-2 receptor and related proteins in the male reproductive tract and the association of serum testosterone levels with viral entry and infection have brought attention to COVID-19's effects on male fertility.

METHODS

The peer-reviewed articles and reviews were obtained by searching for the keywords SARS-CoV-2, COVID-19, endocrine, spermatogenesis, epididymis, prostate, and vaccine in the databases of PubMed, Web of Science and Google Scholar from 2020-2022.

RESULTS

This review summarizes the effects of COVID-19 on the male reproductive system and investigates the impact of various types of SARS-CoV-2 vaccines on male reproductive health. We also present the underlying mechanisms by which SARS-CoV-2 affects male reproduction and discuss the potentially harmful effects of asymptomatic infections, as well as the long-term impact of COVID-19 on male reproductive health.

CONCLUSION

COVID-19 disrupted the HPG axis, which had negative impacts on spermatogenesis and the epididymis, albeit further investigations need to be performed. The development of vaccines against various SARS-CoV-2 variations is important to lower infection rates and long-term COVID risks.

Innate and adaptive immunity to SARS-CoV-2 and predisposing factors

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus (SARS-CoV-2), has affected all countries worldwide. Although some symptoms are relatively mild, others are still associated with severe and even fatal clinical outcomes. Innate and adaptive immunity are important for the control of SARS-CoV-2 infections, whereas a comprehensive characterization of the innate and adaptive immune response to COVID-19 is still lacking and the mechanisms underlying immune pathogenesis and host predisposing factors are still a matter of scientific debate. Here, the specific functions and kinetics of innate and adaptive immunity involved in SARS-CoV-2 recognition and resultant pathogenesis are discussed, as well as their immune memory for vaccinations, viral-mediated immune evasion, and the current and future immunotherapeutic agents. We also highlight host factors that contribute to infection, which may deepen the understanding of viral pathogenesis and help identify targeted therapies that attenuate severe disease and infection.

The Impact of COVID-19 on People Living with HIV-1 and HIV-1-Associated Neurological Complications

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the causative pathogen of the coronavirus disease 2019 (COVID-19) pandemic, a fatal respiratory illness. The associated risk factors for COVID-19 are old age and medical comorbidities. In the current combined antiretroviral therapy (cART) era, a significant portion of people living with HIV-1 (PLWH) with controlled viremia is older and with comorbidities, making these people vulnerable to SARS-CoV-2 infection and COVID-19-associated severe outcomes. Additionally, SARS-CoV-2 is neurotropic and causes neurological complications, resulting in a health burden and an adverse impact on PLWH and exacerbating HIV-1-associated neurocognitive disorder (HAND). The impact of SARS-CoV-2 infection and COVID-19 severity on neuroinflammation, the development of HAND and preexisting HAND is poorly explored. In the present review, we compiled the current knowledge of differences and similarities between SARS-CoV-2 and HIV-1, the conditions of the SARS-CoV-2/COVID-19 and HIV-1/AIDS syndemic and their impact on the central nervous system (CNS). Risk factors of COVID-19 on PLWH and neurological manifestations, inflammatory mechanisms leading to the neurological syndrome, the development of HAND, and its influence on preexisting HAND are also discussed. Finally, we have reviewed the challenges of the present syndemic on the world population, with a particular emphasis on PLWH.

Discovery of Highly Potent Small Molecule Pan-Coronavirus Fusion Inhibitors

The unprecedented pandemic of COVID-19, caused by a novel coronavirus, SARS-CoV-2, and its highly transmissible variants, led to massive human suffering, death, and economic devastation worldwide. Recently, antibody-evasive SARS-CoV-2 subvariants, BQ and XBB, have been reported. Therefore, the continued development of novel drugs with pan-coronavirus inhibition is critical to treat and prevent infection of COVID-19 and any new pandemics that may emerge. We report the discovery of several highly potent small-molecule inhibitors. One of which, NBCoV63, showed low nM potency against SARS-CoV-2 (IC₅₀: 55 nM), SARS-CoV-1 (IC₅₀: 59 nM), and MERS-CoV (IC₅₀: 75 nM) in pseudovirus-based assays with excellent selectivity indices (SI > 900), suggesting its pan-coronavirus inhibition. NBCoV63 showed equally effective antiviral potency against SARS-CoV-2 mutant (D614G) and several variants of concerns (VOCs) such as B.1.617.2 (Delta), B.1.1.529/BA.1 and BA.4/BA.5 (Omicron), and K417T/E484K/N501Y (Gamma). NBCoV63 also showed similar efficacy profiles to Remdesivir against authentic SARS-CoV-2 (Hong Kong strain) and two of its variants (Delta and Omicron), SARS-CoV-1, and MERS-CoV by plaque reduction in Calu-3 cells. Additionally, we show that NBCoV63 inhibits virus-mediated cell-to-cell fusion in a dose-dependent manner. Furthermore, the absorption, distribution, metabolism, and excretion (ADME) data of NBCoV63 demonstrated drug-like properties.

Sex hormones in SARS-CoV-2 susceptibility: key players or confounders?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has a clear sex disparity in clinical outcomes. Hence, the interaction between sex hormones, virus entry receptors and immune responses has attracted major interest as a target for the prevention and treatment of SARS-CoV-2 infections. This Review summarizes the current understanding of the roles of androgens, oestrogens and progesterone in the regulation of virus entry receptors and disease progression of coronavirus disease 2019 (COVID-19) as well as their therapeutic value. Although many experimental and clinical studies have analysed potential mechanisms by which female sex hormones might provide protection against SARS-CoV-2 infectivity, there is currently no clear evidence for a sex-specific expression of virus entry receptors. In addition, reports describing an influence of oestrogen, progesterone and androgens on the course of COVID-19 vary widely. Current data also do not support the administration of oestradiol in COVID-19. The conflicting evidence and lack of consensus results from a paucity of mechanistic studies and clinical trials reporting sex-disaggregated data. Further, the influence of variables beyond biological factors (sex), such as sociocultural factors (gender), on COVID-19 manifestations has not been investigated. Future research will have to fill this knowledge gap as the influence of sex and gender on COVID-19 will be essential to understanding and managing the long-term consequences of this pandemic.

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.

Systematic Guidelines for Effective Utilization of COVID-19 Databases in Genomic, Epidemiologic, and Clinical Research

The pandemic has led to the production and accumulation of various types of data related to coronavirus disease 2019 (COVID-19). To understand the features and characteristics of COVID-19 data, we summarized representative databases and determined the data types, purpose, and utilization details of each database. In addition, we categorized COVID-19 associated databases into epidemiological data, genome and protein data, and drug and target data. We found that the data present in each of these databases have nine separate purposes (clade/variant/lineage, genome browser, protein structure, epidemiological data, visualization, data analysis tool, treatment, literature, and immunity) according to the types of data. Utilizing the databases we investigated, we created four queries as integrative analysis methods that aimed to answer important scientific questions related to COVID-19. Our queries can make effective use of multiple databases to produce valuable results that can reveal novel findings through comprehensive analysis. This allows clinical researchers, epidemiologists, and clinicians to have easy access to COVID-19 data without requiring expert knowledge in computing or data science. We expect that users will be able to reference our examples to construct their own integrative analysis methods, which will act as a basis for further scientific inquiry and data searching.

Folic Acid and Leucovorin Have Potential to Prevent SARS-CoV-2-Virus Internalization by Interacting with S-Glycoprotein/Neuropilin-1 Receptor Complex

The interaction of the SARS-CoV-2 spike (S) glycoprotein receptor-binding domain with the host-cell ACE2 receptor is a well-known step in virus infection. Neuropilin-1 (NRP-1) is another host factor involved in virus internalization. The interaction between S-glycoprotein and NRP-1 has been identified as a potential COVID-19 treatment target. Herein, the effectiveness of folic acid and leucovorin in preventing contact between S-glycoprotein and NRP-1 receptors was investigated using in silico studies and then confirmed in vitro. The results of a molecular docking study showed that leucovorin and folic acid had lower binding energies than EG01377, a well-known NRP-1 inhibitor, and lopinavir. Two hydrogen bonds with Asp 320 and Asn 300 residues stabilized the leucovorin, while interactions with Gly 318, Thr 349, and Tyr 353 residues stabilized the folic acid. The molecular dynamic simulation revealed that the folic acid and leucovorin created very stable complexes with the NRP-1. The in vitro studies showed that the leucovorin was the most active inhibitor of the S1-glycoprotein/NRP-1 complex formation, with an IC₇₅ value of 185.95 µg/mL. The results of this study suggest that folic acid and leucovorin could be considered as potential inhibitors of the S-glycoprotein/NRP-1 complex and, thus, could prevent the SARS-CoV-2 virus' entry into host cells.

Current status in cellular-based therapies for prevention and treatment of COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the pathogen responsible for the coronavirus disease 2019 (COVID-19) outbreaks that resulted in a catastrophic threat to global health, with more than 500 million cases detected and 5.5 million deaths worldwide. Patients with a COVID-19 infection presented with clinical manifestations ranging from asymptomatic to severe symptoms, resulting in acute lung injury, acute respiratory distress syndrome, and even death. Immune dysregulation through delayed innate immune response or impairment of the adaptive immune response is the key contributor to the pathophysiology of COVID-19 and SARS-CoV-2-induced cytokine storm. Symptomatic and supportive therapy is the fundamental strategy in treating COVID-19 infection, including antivirals, steroid-based therapies, and cell-based immunotherapies. Various studies reported substantial effects of immune-based therapies for patients with COVID-19 to modulate the over-activated immune system while simultaneously refining the body's ability to destroy the virus. However, challenges may arise from the complexity of the disease through the genetic variance of the virus itself and patient heterogeneity, causing increased transmissibility and heightened immune system evasion that rapidly change the intervention and prevention measures for SARS-CoV-2. Cell-based therapy, utilizing stem cells, dendritic cells, natural killer cells, and T cells, among others, are being extensively explored as other potential immunological approaches for preventing and treating SARS-CoV-2-affected patients the similar process was effectively proven in SARS-CoV-1 and MERS-CoV infections. This review provides detailed insights into the innate and adaptive immune response-mediated cell-based immunotherapies in COVID-19 patients. The immune response linking towards engineered autologous or allogenic immune cells for either treatment or preventive therapies is subsequently highlighted in an individual study or in combination with several existing treatments. Up-to-date data on completed and ongoing clinical trials of cell-based agents for preventing or treating COVID-19 are also outlined to provide a guide that can help in treatment decisions and future trials.

Protease-Responsive Potential-Tunable AIEgens for Cell Selective Imaging of TMPRSS2 and Accurate Inhibitor Screening

Transmembrane protease serine 2 (TMPRSS2) is a plasma membrane protease that activates both spike protein of coronaviruses for cell entry and oncogenic signaling pathways for tumor progression. TMPRSS2 inhibition can reduce cancer invasion and metastasis and partially prevent the entry of SARS-CoV-2 into host cells. Thus, there is an urgent need for both TMPRSS2-selective imaging and precise screening of TMPRSS2 inhibitors. Here, we report a TMPRSS2-responsive surface-potential-tunable peptide-conjugated probe (EGTP) with aggregation-induced emission (AIE) features for TMPRSS2 selective imaging and accurate inhibitor screening. The amphiphilic EGTP was constructed with tunable surface potential and responsive efficiency with TMPRSS2 and its inhibitor. The rational construction of AIE luminogens (AIEgens) with modular peptides indicated that the cleavage of EGTP led to a gradual aggregation with bright fluorescence in high TMPRSS2-expressing cells. This strategy may have value for selective detection of cancer cells, SARS-CoV-2-target cells, and screening of protease inhibitors.

LRRC15 mediates an accessory interaction with the SARS-CoV-2 spike protein

The interactions between Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and human host factors enable the virus to propagate infections that lead to Coronavirus Disease 2019 (COVID-19). The spike protein is the largest structural component of the virus and mediates interactions essential for infection, including with the primary angiotensin-converting enzyme 2 (ACE2) receptor. We performed two independent cell-based systematic screens to determine whether there are additional proteins by which the spike protein of SARS-CoV-2 can interact with human cells. We discovered that in addition to ACE2, expression of LRRC15 also causes spike protein binding. This interaction is distinct from other known spike attachment mechanisms such as heparan sulfates or lectin receptors. Measurements of orthologous coronavirus spike proteins implied the interaction was functionally restricted to SARS-CoV-2 by accessibility. We localized the interaction to the C-terminus of the S1 domain and showed that LRRC15 shares recognition of the ACE2 receptor binding domain. From analyzing proteomics and single-cell transcriptomics, we identify LRRC15 expression as being common in human lung vasculature cells and fibroblasts. Levels of LRRC15 were greatly elevated by inflammatory signals in the lungs of COVID-19 patients. Although infection assays demonstrated that LRRC15 alone is not sufficient to permit viral entry, we present evidence that it can modulate infection of human cells. This unexpected interaction merits further investigation to determine how SARS-CoV-2 exploits host LRRC15 and whether it could account for any of the distinctive features of COVID-19.

A SARS-CoV-2 impedimetric biosensor based on the immobilization of ACE-2 receptor-containing entire cell membranes as the biorecognition element

A SARS-CoV-2 biosensor based on the biorecognition of the spike protein to the angiotensin-converting enzyme 2 (ACE-2) transmembrane receptor was developed using entire cell membranes as the biorecognition layer. In this new SARS-CoV-2 detection platform, cellular membranes from VeroCCL81 (mVero) and Calu-3 (mCalu) cells (which overexpress the ACE-2 transmembrane receptors) were extracted and immobilized as vesicles on an indium tin oxide electrode (ITO). Electrochemical impedance spectroscopy was used to optimize the performance of the developed devices for SARS-CoV-2 detection. This novel biosensor comprises a low-cost system (less than one US$ dollar) that uses the unique properties of cell membranes combined with the catalytic properties of electrochemical platforms to allow spike proteins recognition. A linear response from 10 to 100 ng/mL was obtained from the optimized biosensors, a limit of detection of 10.0 pg/mL and 7.25 pg/mL and limit of quantification of 30.4 pg/mL and 21.9 pg/mL were achieved with satisfactory accuracy for ITO-APTES-mVero and ITO-APTES-mCalu, respectively. Selectivity studies revealed that this platform was able to differentiate the target spike proteins from NS1 proteins from dengue and Zika viruses. In addition, sensors comprising cell membranes devoid of the ACE-2 transmembrane receptor exhibited no biorecognition signal. The developed devices are suitable for SARS-CoV-2 detection based on spike protein recognition, and capable of providing a low-cost, accurate, and accessible tool for use in a pandemic and post-pandemic scenario.

Regulation of angiotensin-converting enzyme 2 isoforms by type 2 inflammation and viral infection in human airway epithelium

SARS-CoV-2 enters human cells through its main receptor, angiotensin-converting enzyme 2 (ACE2), which constitutes a limiting factor of infection. Recent findings demonstrating novel ACE2 isoforms implicate that this receptor is regulated in a more complex way than previously anticipated. However, it remains unknown how various inflammatory conditions influence the abundance of these ACE2 variants. Hence, we studied expression of ACE2 messenger RNA (mRNA) and protein isoforms, together with its glycosylation and spatial localization in primary human airway epithelium upon allergic inflammation and viral infection. We found that interleukin-13, the main type 2 cytokine, decreased expression of long ACE2 mRNA and reduced glycosylation of full-length ACE2 protein via alteration of N-linked glycosylation process, limiting its availability on the apical side of ciliated cells. House dust mite allergen did not affect the expression of ACE2. Rhinovirus infection increased short ACE2 mRNA, but it did not influence its protein expression. In addition, by screening other SARS-CoV-2 related host molecules, we found that interleukin-13 and rhinovirus significantly regulated mRNA, but not protein of transmembrane serine protease 2 and neuropilin 1. Regulation of ACE2 and other host proteins was comparable in healthy and asthmatic epithelium, underlining the lack of intrinsic differences but dependence on the inflammatory milieu in the airways.

Ocular Symptoms Associated with COVID-19 Are Correlated with the Expression Profile of Mouse SARS-CoV-2 Binding Sites

The COVID-19 pandemic has engendered significant scientific efforts in the understanding of its infectious agent SARS-CoV-2 and of its associated symptoms. A peculiar characteristic of this virus lies in its ability to challenge our senses, as its infection can lead to anosmia and ageusia. While ocular symptoms, such as conjunctivitis, optic neuritis or dry eyes, are also reported after viral infection, they have lower frequencies and severities, and their functional development is still elusive. Here, using combined technical approaches based on histological and gene profiling methods, we characterized the expression of SARS-CoV-2 binding sites (Ace2/Tmprss2) in the mouse eye. We found that ACE2 was ectopically expressed in subtissular ocular regions, such as in the optic nerve and in the Harderian/intraorbital lacrimal glands. Moreover, we observed an important variation of Ace2/Tmprss2 expression that is not only dependent on the age and sex of the animal, but also highly heterogenous between individuals. Our results thus give new insight into the expression of SARS-CoV-2 binding sites in the mouse eye and propose an interpretation of the human ocular-associated symptoms linked to SARS-CoV-2.

S Protein, ACE2 and Host Cell Proteases in SARS-CoV-2 Cell Entry and Infectivity; Is Soluble ACE2 a Two Blade Sword? A Narrative Review

Since the spread of the deadly virus SARS-CoV-2 in late 2019, researchers have restlessly sought to unravel how the virus enters the host cells. Some proteins on each side of the interaction between the virus and the host cells are involved as the major contributors to this process: (1) the nano-machine spike protein on behalf of the virus, (2) angiotensin converting enzyme II, the mono-carboxypeptidase and the key component of renin angiotensin system on behalf of the host cell, (3) some host proteases and proteins exploited by SARS-CoV-2. In this review, the complex process of SARS-CoV-2 entrance into the host cells with the contribution of the involved host proteins as well as the sequential conformational changes in the spike protein tending to increase the probability of complexification of the latter with angiotensin converting enzyme II, the receptor of the virus on the host cells, are discussed. Moreover, the release of the catalytic ectodomain of angiotensin converting enzyme II as its soluble form in the extracellular space and its positive or negative impact on the infectivity of the virus are considered.

The role of oxidative stress in the pathogenesis of infections with coronaviruses

Coronaviruses can cause serious respiratory tract infections and may also impact other end organs such as the central nervous system, the lung and the heart. The coronavirus disease 2019 (COVID-19) has had a devastating impact on humanity. Understanding the mechanisms that contribute to the pathogenesis of coronavirus infections, will set the foundation for development of new treatments to attenuate the impact of infections with coronaviruses on host cells and tissues. During infection of host cells, coronaviruses trigger an imbalance between increased production of reactive oxygen species (ROS) and reduced antioxidant host responses that leads to increased redox stress. Subsequently, increased redox stress contributes to reduced antiviral host responses and increased virus-induced inflammation and apoptosis that ultimately drive cell and tissue damage and end organ disease. However, there is limited understanding how different coronaviruses including SARS-CoV-2, manipulate cellular machinery that drives redox responses. This review aims to elucidate the redox mechanisms involved in the replication of coronaviruses and associated inflammation, apoptotic pathways, autoimmunity, vascular dysfunction and tissue damage that collectively contribute to multiorgan damage.

Aptamer-based Emerging Tools for Viral Biomarker Detection: A Focus on SARS-CoV-2

Viral infections can cause fatal illnesses to humans as well as animals. Early detection of viruses is therefore crucial to provide effective treatment to patients. Recently, the Covid-19 pandemic has undoubtedly given an alarming call to develop rapid and sensitive detection platforms. The viral diagnostic tools need to be fast, affordable, and easy to operate with high sensitivity and specificity equivalent or superior to the currently used diagnostic methods. The present detection methods include direct detection of viral antigens or measuring the response of antibodies to viral infections. However, the sensitivity and quantification of the virus are still a significant challenge. Detection tools employing synthetic binding molecules like aptamers may provide several advantages over the conventional methods that use antibodies in the assay format. Aptamers are highly stable and tailorable molecules and are therefore ideal for detection and chemical sensing applications. This review article discusses various advances made in aptamer-based viral detection platforms, including electrochemical, optical, and colorimetric methods to detect viruses, specifically SARS-Cov-2. Considering the several advantages, aptamers could be game-changing in designing high-throughput biosensors for viruses and other biomedical applications in the future.

Appearing and disappearing acts of cilia

The past few decades have seen a rise in research on vertebrate cilia and ciliopathy, with interesting collaborations between basic and clinical scientists. This work includes studies on ciliary architecture, composition, evolution, and organelle generation and its biological role. The human body has cells that harbour any of the following four types of cilia: 9+0 motile, 9+0 immotile, 9+2 motile, and 9+2 immotile. Depending on the type, cilia play an important role in cell/fluid movement, mating, sensory perception, and development. Defects in cilia are associated with a wide range of human diseases afflicting the brain, heart, kidneys, respiratory tract, and reproductive system. These are commonly known as ciliopathies and affect millions of people worldwide. Due to their complex genetic etiology, diagnosis and therapy have remained elusive. Although model organisms like Chlamydomonas reinhardtii have been a useful source for ciliary research, reports of a fascinating and rewarding translation of this research into mammalian systems, especially humans, are seen. The current review peeks into one of the complex features of this organelle, namely its birth, the common denominators across the formation of both 9+0 and 9+2 ciliary types, the molecules involved in ciliogenesis, and the steps that go towards regulating their assembly and disassembly.

In vitro infection of human ocular tissues by SARS-CoV-2 lineage A isolates

BACKGROUND

The purpose of this study was: [1] to evaluate the infectivity of two SARS-CoV-2 lineage A variants on human ocular tissues in vitro, and [2] to evaluate the stability of SARS-CoV-2 lineage A variants in corneal preservation medium.

METHODS

Primary cultures of donor corneal, conjunctival, and limbal epithelium were inoculated with two lineage A, GISAID clade S isolates of SARS-CoV-2 (Hong Kong/VM20001061/2020, USA-WA1/2020), to evaluate the susceptibility of the ocular tissue to infection. Flat-mounted Descemet's Stripping Automated Endothelial Keratoplasty (DSAEK) grafts were inoculated with SARS-CoV-2 to evaluate the susceptibility of the endothelium to infection. All inoculated samples were immunostained for SARS-CoV-2 nucleocapsid (N)-protein expression to confirm positive infection. SARS-CoV-2 Hong Kong was then inoculated into cornea preservation media (Life4°C, Numedis, Inc.). Inoculated media was stored at 4^oC for 14 days and assayed over time for changes in infectious viral titers.

RESULTS

Corneal, conjunctival, and limbal epithelial cells all demonstrated susceptibility to infection by SARS-CoV-2 lineage A variants. Conjunctiva demonstrated the highest infection rate (78% of samples infected [14/18]); however, infection rates did not differ statistically between cell types and viral isolates. After inoculation, 40% (4/10) of DSAEK grafts had active infection in the endothelium. SARS-CoV-2 lineage A demonstrated < 1 log decline in viral titers out to 14 days in corneal preservation media.

CONCLUSIONS

SARS-CoV-2 lineage A variants can infect corneal, limbal, and conjunctival epithelium, as well as corneal endothelium. There was no statistical difference in infectivity between different lineage A variants. SARS-CoV-2 lineage A can survive and remain infectious in corneal preservation media out to 14 days in cold storage.

Control of SARS-CoV-2 infection by MT1-MMP-mediated shedding of ACE2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a global pandemic. Angiotensin-converting enzyme 2 (ACE2) is an entry receptor for SARS-CoV-2. The full-length membrane form of ACE2 (memACE2) undergoes ectodomain shedding to generate a shed soluble form (solACE2) that mediates SARS-CoV-2 entry via receptor-mediated endocytosis. Currently, it is not known how the physiological regulation of ACE2 shedding contributes to the etiology of COVID-19 in vivo. The present study identifies Membrane-type 1 Matrix Metalloproteinase (MT1-MMP) as a critical host protease for solACE2-mediated SARS-CoV-2 infection. SARS-CoV-2 infection leads to increased activation of MT1-MMP that is colocalized with ACE2 in human lung epithelium. Mechanistically, MT1-MMP directly cleaves memACE2 at M706-S to release solACE2_18-706 that binds to the SARS-CoV-2 spike proteins (S), thus facilitating cell entry of SARS-CoV-2. Human solACE2_18-706 enables SARS-CoV-2 infection in both non-permissive cells and naturally insusceptible C57BL/6 mice. Inhibition of MT1-MMP activities suppresses solACE2-directed entry of SARS-CoV-2 in human organoids and aged mice. Both solACE2 and circulating MT1-MMP are positively correlated in plasma of aged mice and humans. Our findings provide in vivo evidence demonstrating the contribution of ACE2 shedding to the etiology of COVID-19.

Development of Fluorescence-Tagged SARS-CoV-2 Virus-like Particles by a Tri-Cistronic Vector Expression System for Investigating the Cellular Entry of SARS-CoV-2

Severe acute respiratory syndrome-related coronavirus-2 (SARS-CoV-2) has caused the pandemic that began late December 2019. The co-expression of SARS-CoV-2 structural proteins in cells could assemble into several types of virus-like particles (VLPs) without a viral RNA genome. VLPs containing S proteins with the structural and functional properties of authentic virions are safe materials to exploit for virus-cell entry and vaccine development. In this study, to generate SARS-CoV-2 VLPs (SCoV2-SEM VLPs) composed of three structural proteins including spike (S), envelop (E) protein and membrane (M) protein, a tri-cistronic vector expression system was established in a cell line co-expressing SARS-CoV-2 S, E and M proteins. The SCoV2-SEM VLPs were harvested from the cultured medium, and three structure proteins were confirmed by Western blot assay. A negative-stain TEM assay demonstrated the size of the SCoV2-SEM VLPs with a diameter of about 90 nm. To further characterize the infectious properties of SCoV2-SEM VLPs, the VLPs (atto647N-SCoV2-SEM VLPs) were fluorescence-labeled by conjugation with atto-647N and visualized under confocal microscopy at a single-particle resolution. The results of the infection assay revealed that atto647N-SCoV2-SEM VLPs attached to the surface of the HEK293T cells at the pre-binding phase in a ACE2-dependent manner. At the post-infection phase, atto647N-SCoV2-SEM VLPs either fused with the cellular membrane or internalized into the cytoplasm with mCherry-rab5-positive early endosomes. Moreover, fusion with the cellular membrane and the internalization with early endosomes could be inhibited by the treatment of camostat (a pharmacological inhibitor of TMPRSS2) and chlorpromazine (an endocytosis inhibitor), respectively. These results elucidated that SCoV2-SEM VLPs behave similarly to the authentic live SARS-CoV-2 virus, suggesting that the development of SCoV2-SEM VLPs provide a realistic and safe experimental model for studying the infectious mechanism of SARS-CoV-2.

COVID-19 infection and vaccine have no impact on in-vitro fertilization (IVF) outcome

To investigate the effect of COVID-19 infection or vaccine on IVF outcome. This is a multicenter retrospective study. Data were collected from all patients treated in the ART units between September and November 2021 after the vaccination of the general population began. Medical records of all patients who had IVF/intracytoplasmic sperm injection (ICSI) were retrospectively reviewed. Patients were categorized into four groups: previously infected by COVID-19, vaccinated by COVID vaccine, previously infected and vaccinated, or neither infected nor vaccinated. Total number of participants 151 (vaccinated only 66, infected only 18, vaccinated and previously infected 34, and control 33. Outcomes (ET on day of trigger, number of oocytes retrieved, quality of oocytes, number of fertilized oocytes, number and quality of embryos, number of embryos transferred, number of embryos frozen, implantation rate and clinical pregnancy rate) were compared between these four groups. Moreover, we compared the outcome before and post infection, as well as before and post vaccine in a group of patients. No evidence was found to suggest that COVID-19 disease or SARS-CoV-2 Vaccine adversely affects Clinical pregnancy rates (positive fetal heartbeat) (OR 0.9, CI 0.5-1.9, OR 1.8, CI 0.9-3.6, respectively) and the following parameters: fertilization rate, implantation rate, positive bHcg) (OR 0.9, CI 0.5-1.8, OR 1.5, CI 0.7-2.9, respectively). Although a limitation of our study is the small comparison groups, and the wide confidence intervals in the Odds Ratio estimates.

Genetic Variants and Protective Immunity against SARS-CoV-2

The novel coronavirus-19 (SARS-CoV-2), has infected numerous individuals worldwide, resulting in millions of fatalities. The pandemic spread with high mortality rates in multiple waves, leaving others with moderate to severe symptoms. Co-morbidity variables, including hypertension, diabetes, and immunosuppression, have exacerbated the severity of COVID-19. In addition, numerous efforts have been made to comprehend the pathogenic and host variables that contribute to COVID-19 susceptibility and pathogenesis. One of these endeavours is understanding the host genetic factors predisposing an individual to COVID-19. Genome-Wide Association Studies (GWAS) have demonstrated the host predisposition factors in different populations. These factors are involved in the appropriate immune response, their imbalance influences susceptibility or resistance to viral infection. This review investigated the host genetic components implicated at the various stages of viral pathogenesis, including viral entry, pathophysiological alterations, and immunological responses. In addition, the recent and most updated genetic variations associated with multiple host factors affecting COVID-19 pathogenesis are described in the study.

Use of Antiandrogens as Therapeutic Agents in COVID-19 Patients

COVID-19, caused by the severe acute respiratory syndrome coronavirus 2 (SARS CoV-2), is estimated to have caused over 6.5 million deaths worldwide. The emergence of fast-evolving SARS-CoV-2 variants of concern alongside increased transmissibility and/or virulence, as well as immune and vaccine escape capabilities, highlight the urgent need for more effective antivirals to combat the disease in the long run along with regularly updated vaccine boosters. One of the early risk factors identified during the COVID-19 pandemic was that men are more likely to become infected by the virus, more likely to develop severe disease and exhibit a higher likelihood of hospitalisation and mortality rates compared to women. An association exists between SARS-CoV-2 infectiveness and disease severity with sex steroid hormones and, in particular, androgens. Several studies underlined the importance of the androgen-mediated regulation of the host protease TMPRSS2 and the cell entry protein ACE2, as well as the key role of these factors in the entry of the virus into target cells. In this context, modulating androgen signalling is a promising strategy to block viral infection, and antiandrogens could be used as a preventative measure at the pre- or early hospitalisation stage of COVID-19 disease. Different antiandrogens, including commercial drugs used to treat metastatic castration-sensitive prostate cancer and other conditions, have been tested as antivirals with varying success. In this review, we summarise the most recent updates concerning the use of antiandrogens as prophylactic and therapeutic options for COVID-19.

DNA methylation profiles in pneumonia patients reflect changes in cell types and pneumonia severity

Immune cell-type composition changes with age, potentially weakening the response to infectious diseases. Profiling epigenetics marks of immune cells can help us understand the relationship with disease severity. We therefore leveraged a targeted DNA methylation method to study the differences in a cohort of pneumonia patients (both COVID-19 positive and negative) and unaffected individuals from peripheral blood.This approach allowed us to predict the pneumonia diagnosis with high accuracy (AUC = 0.92), and the PCR positivity to the SARS-CoV-2 viral genome with moderate, albeit lower, accuracy (AUC = 0.77). We were also able to predict the severity of pneumonia (PORT score) with an R² = 0.69. By estimating immune cellular frequency from DNA methylation data, patients under the age of 65 positive to the SARS-CoV-2 genome (as revealed by PCR) showed an increase in T cells, and specifically in CD8+ cells, compared to the negative control group. Conversely, we observed a decreased frequency of neutrophils in the positive compared to the negative group. No significant difference was found in patients over the age of 65. The results suggest that this DNA methylation-based approach can be used as a cost-effective and clinically useful biomarker platform for predicting pneumonias and their severity.

Human lungs show limited permissiveness for SARS-CoV-2 due to scarce ACE2 levels but virus-induced expansion of inflammatory macrophages

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) utilises the angiotensin-converting enzyme 2 (ACE2) transmembrane peptidase as cellular entry receptor. However, whether SARS-CoV-2 in the alveolar compartment is strictly ACE2-dependent and to what extent virus-induced tissue damage and/or direct immune activation determines early pathogenesis is still elusive.

METHODS

Spectral microscopy, single-cell/-nucleus RNA sequencing or ACE2 "gain-of-function" experiments were applied to infected human lung explants and adult stem cell derived human lung organoids to correlate ACE2 and related host factors with SARS-CoV-2 tropism, propagation, virulence and immune activation compared to SARS-CoV, influenza and Middle East respiratory syndrome coronavirus (MERS-CoV). Coronavirus disease 2019 (COVID-19) autopsy material was used to validate ex vivo results.

RESULTS

We provide evidence that alveolar ACE2 expression must be considered scarce, thereby limiting SARS-CoV-2 propagation and virus-induced tissue damage in the human alveolus. Instead, ex vivo infected human lungs and COVID-19 autopsy samples showed that alveolar macrophages were frequently positive for SARS-CoV-2. Single-cell/-nucleus transcriptomics further revealed nonproductive virus uptake and a related inflammatory and anti-viral activation, especially in "inflammatory alveolar macrophages", comparable to those induced by SARS-CoV and MERS-CoV, but different from NL63 or influenza virus infection.

CONCLUSIONS

Collectively, our findings indicate that severe lung injury in COVID-19 probably results from a macrophage-triggered immune activation rather than direct viral damage of the alveolar compartment.

Impact of the Human Cell Atlas on medicine

Single-cell atlases promise to provide a 'missing link' between genes, diseases and therapies. By identifying the specific cell types, states, programs and contexts where disease-implicated genes act, we will understand the mechanisms of disease at the cellular and tissue levels and can use this understanding to develop powerful disease diagnostics; identify promising new drug targets; predict their efficacy, toxicity and resistance mechanisms; and empower new kinds of therapies, from cancer therapies to regenerative medicine. Here, we lay out a vision for the potential of cell atlases to impact the future of medicine, and describe how advances over the past decade have begun to realize this potential in common complex diseases, infectious diseases (including COVID-19), rare diseases and cancer.

Host transcriptional responses in nasal swabs identify potential SARS-CoV-2 infection in PCR negative patients

We analyzed RNA sequencing data from nasal swabs used for SARS-CoV-2 testing. 13% of 317 PCR-negative samples contained over 100 reads aligned to multiple regions of the SARS-CoV-2 genome. Differential gene expression analysis compares the host gene expression in potential false-negative (FN: PCR negative, sequencing positive) samples to subjects with multiple SARS-CoV-2 viral loads. The host transcriptional response in FN samples was distinct from true negative samples (PCR & sequencing negative) and similar to low viral load samples. Gene Ontology analysis shows viral load-dependent changes in gene expression are functionally distinct; 23 common pathways include responses to viral infections and associated immune responses. GO analysis reveals FN samples had a high overlap with high viral load samples. Deconvolution of RNA-seq data shows similar cell content across viral loads. Hence, transcriptome analysis of nasal swabs provides an additional level of identifying SARS-CoV-2 infection.

E-Cigarette Vapour Increases ACE2 and TMPRSS2 Expression in a Flavour- and Nicotine-Dependent Manner

COVID-19 infects via the respiratory system, but it can affect multiple systems and lead to multi system failure. There is growing evidence that smoking may be associated with higher rates of COVID-19 infections and worse outcomes due to increased levels of ACE2 in lung epithelial cells, but it is unknown whether E-cigarette use may lead to increased risk of COVID-19 infection from the SARS-CoV-2 virus. In this study, healthy donor bronchial epithelial cells (NHBE) and monocyte-derived macrophages (MDM) were exposed to cigarette smoke extract (CSE) or nicotine or flavoured E-cigarette vapour extract (EVE) before the assessment of SARS-CoV-2 recognition receptors ACE2 and TMPRSS2 genes. MDMs exposed to CSE and Tobacco EVE showed increased ACE2 expression; however, no treatment altered the TMPRSS2 expression. ACE2 was found to be upregulated by >2-fold in NHBE cells exposed to CSE, as well as nicotine, banana, or chocolate EVE, while TMPRSS2 was only upregulated by CSE or nicotine EVE exposure. These findings suggesting that flavourings can increase ACE2 expression in multiple cell types, while TMPRSS2 expression increases are limited to the epithelial cells in airways and may be limited to nicotine and/or cigarette smoke exposure. Therefore, increased risk of COVID-19 infection cannot be ruled out for vapers.

Vascular dysfunction in COVID-19 patients: update on SARS-CoV-2 infection of endothelial cells and the role of long non-coding RNAs

Although COVID-19 is primarily a respiratory disease, it may affect also the cardiovascular system. COVID-19 patients with cardiovascular disorder (CVD) develop a more severe disease course with a significantly higher mortality rate than non-CVD patients. A common denominator of CVD is the dysfunction of endothelial cells (ECs), increased vascular permeability, endothelial-to-mesenchymal transition, coagulation, and inflammation. It has been assumed that clinical complications in COVID-19 patients suffering from CVD are caused by SARS-CoV-2 infection of ECs through the angiotensin-converting enzyme 2 (ACE2) receptor and the cellular transmembrane protease serine 2 (TMPRSS2) and the consequent dysfunction of the infected vascular cells. Meanwhile, other factors associated with SARS-CoV-2 entry into the host cells have been described, including disintegrin and metalloproteinase domain-containing protein 17 (ADAM17), the C-type lectin CD209L or heparan sulfate proteoglycans (HSPG). Here, we discuss the current data about the putative entry of SARS-CoV-2 into endothelial and smooth muscle cells. Furthermore, we highlight the potential role of long non-coding RNAs (lncRNAs) affecting vascular permeability in CVD, a process that might exacerbate disease in COVID-19 patients.

Infección natural por SARS-CoV-2 en gatos y perros domésticos de personas con diagnóstico de COVID-19 en el Valle de Aburrá, Antioquia

Introducción. El síndrome respiratorio agudo grave causado por el nuevo coronavirus SARSCoV-2 es causa de la emergencia sanitaria por la pandemia de COVID-19. Si bien el humano es el el principal huésped vulnerable, en estudios experimentales y reportes de infección natural, se han encontrado casos de zoonosis inversa de SARS-CoV-2 en animales.Objetivo. Evaluar la infección natural por SARS-CoV-2 en gatos y perros de propietarios con diagnóstico de COVID-19 en el Valle de Aburrá, Antioquia, Colombia.Materiales y métodos. La circulación del SARS-CoV-2 se evaluó por RT-qPCR y RT-PCR en muestras de frotis nasofaríngeos y orofaríngeos de gatos y perros cuyos propietarios se encontraban dentro del periodo de los 14 días de aislamiento. Los casos positivos se verificaron amplificando fragmentos de los genes RdRp, N y E; se secuenció el gen RdRp y se analizó filogenéticamente.Resultados. De 80 animales evaluados, seis gatos y tres perros fueron casos confirmados de infección natural por SARS-CoV-2. Los animales no presentaron signos clínicos y sus propietarios, que padecían la infección, reportaron únicamente signos leves de la enfermedad sin complicaciones clínicas. En el análisis de una de las secuencias, se encontró un polimorfismo de un solo nucleótido (SNP) con un cambio en la posición 647, con sustitución del aminoácido serina (S) por una isoleucina (I). Los casos se presentaron en los municipios de Caldas, Medellín y Envigado.Conclusiones. Se infiere que la infección natural en los gatos y perros se asocia al contacto directo con un paciente con COVID-19. No obstante, no es posible determinar la virulencia del virus en este huésped, ni su capacidad de transmisión  zoonótica o entre especie.

The FDA-approved drug Auranofin has a dual inhibitory effect on SARS-CoV-2 entry and NF-κB signaling

Patients with severe COVID-19 show an altered immune response that fails to control the viral spread and suffer from exacerbated inflammatory response, which eventually can lead to death. A major challenge is to develop an effective treatment for COVID-19. NF-κB is a major player in innate immunity and inflammatory process. By a high-throughput screening approach, we identified FDA-approved compounds that inhibit the NF-κB pathway and thus dampen inflammation. Among these, we show that Auranofin prevents post-translational modifications of NF-κB effectors and their recruitment into activating complexes in response to SARS-CoV-2 infection or cytokine stimulation. In addition, we demonstrate that Auranofin counteracts several steps of SARS-CoV-2 infection. First, it inhibits a raft-dependent endocytic pathway involved in SARS-CoV-2 entry into host cells; Second, Auranofin alters the ACE2 mobility at the plasma membrane. Overall, Auranofin should prevent SARS-CoV-2 infection and inflammatory damages, offering new opportunities as a repurposable drug candidate to treat COVID-19.

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Original high throughput screening of NF-κB inhibitory drugs

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Auranofin inhibits SARS-CoV-2 replication

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Auranofin increases the ACE2 mobility at the plasma membrane

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Auranofin inhibits ACE-2-dependent SARS-CoV-2 endocytosis

Early suppression of antiviral host response and protocadherins by SARS-CoV-2 Spike protein in THP-1-derived macrophage-like cells

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease-19 (COVID-19). The spike protein (S) of SARS-CoV-2 plays a crucial role in mediating viral infectivity; hence, in an extensive effort to curb the pandemic, many urgently approved vaccines rely on the expression of the S protein, aiming to induce a humoral and cellular response to protect against the infection. Given the very limited information about the effects of intracellular expression of the S protein in host cells, we aimed to characterize the early cellular transcriptomic changes induced by expression of the S protein in THP-1-derived macrophage-like cells. Results showed that a wide variety of genes were differentially expressed, products of which are mainly involved in cell adhesion, homeostasis, and most notably, antiviral and immune responses, depicted by significant downregulation of protocadherins and type I alpha interferons (IFNAs). While initially, the levels of IFNAs were higher in the medium of S protein expressing cells, the downregulation observed on the transcriptomic level might have been reflected by no further increase of IFNA cytokines beyond the 5 h time-point, compared to the mock control. Our study highlights the intrinsic pathogenic role of the S protein and sheds some light on the potential drawbacks of its utilization in the context of vaccination strategies.

Frontline workers: Mediators of mucosal immunity in community acquired pneumonia and COVID-19

The current COVID-19 pandemic has highlighted a need to further understand lung mucosal immunity to reduce the burden of community acquired pneumonia, including that caused by the SARS-CoV-2 virus. Local mucosal immunity provides the first line of defence against respiratory pathogens, however very little is known about the mechanisms involved, with a majority of literature on respiratory infections based on the examination of peripheral blood. The mortality for severe community acquired pneumonia has been rising annually, even prior to the current pandemic, highlighting a significant need to increase knowledge, understanding and research in this field. In this review we profile key mediators of lung mucosal immunity, the dysfunction that occurs in the diseased lung microenvironment including the imbalance of inflammatory mediators and dysbiosis of the local microbiome. A greater understanding of lung tissue-based immunity may lead to improved diagnostic and prognostic procedures and novel treatment strategies aimed at reducing the disease burden of community acquired pneumonia, avoiding the systemic manifestations of infection and excess morbidity and mortality.

Therapeutic prospects of ceRNAs in COVID-19

Since the end of 2019, COVID-19 caused by SARS-CoV-2 has spread worldwide, and the understanding of the new coronavirus is in a preliminary stage. Currently, immunotherapy, cell therapy, antiviral therapy, and Chinese herbal medicine have been applied in the clinical treatment of the new coronavirus; however, more efficient and safe drugs to control the progress of the new coronavirus are needed. Long noncoding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs) may provide new therapeutic targets for novel coronavirus treatments. The first aim of this paper is to review research progress on COVID-19 in the respiratory, immune, digestive, circulatory, urinary, reproductive, and nervous systems. The second aim is to review the body systems and potential therapeutic targets of lncRNAs, miRNAs, and circRNAs in patients with COVID-19. The current research on competing endogenous RNA (ceRNA) (lncRNA-miRNA-mRNA and circRNA-miRNA-mRNA) in SARS-CoV-2 is summarized. Finally, we predict the possible therapeutic targets of four lncRNAs, MALAT1, NEAT1, TUG1, and GAS5, in COVID-19. Importantly, the role of PTEN gene in the ceRNA network predicted by lncRNA MALAT1 and lncRNA TUG1 may help in the discovery and clinical treatment of effective drugs for COVID-19.

Receptor-Binding Domain (RBD) Antibodies Contribute More to SARS-CoV-2 Neutralization When Target Cells Express High Levels of ACE2

Neutralization assays are experimental surrogates for the effectiveness of infection- or vaccine-elicited polyclonal antibodies and therapeutic monoclonal antibodies targeting SARS-CoV-2. However, the measured neutralization can depend on the details of the experimental assay. Here, we systematically assess how ACE2 expression in target cells affects neutralization by antibodies to different spike epitopes in lentivirus pseudovirus neutralization assays. For high ACE2-expressing target cells, receptor-binding domain (RBD) antibodies account for nearly all neutralizing activity in polyclonal human sera. However, for lower ACE2-expressing target cells, antibodies targeting regions outside the RBD make a larger (although still modest) contribution to serum neutralization. These serum-level results are mirrored for monoclonal antibodies: N-terminal domain (NTD) antibodies and RBD antibodies that do not compete for ACE2 binding incompletely neutralize on high ACE2-expressing target cells, but completely neutralize on cells with lower ACE2 expression. Our results show that the ACE2 expression level in the target cells is an important experimental variable, and that high ACE2 expression emphasizes the role of a subset of RBD-directed antibodies.

The COVID-19 pandemic and Alzheimer’s disease: mutual risks and mechanisms

Coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a life-threatening disease, especially in elderly individuals and those with comorbidities. The predominant clinical manifestation of COVID-19 is respiratory dysfunction, while neurological presentations are increasingly being recognized. SARS-CoV-2 invades host cells primarily via attachment of the spike protein to the angiotensin-converting enzyme 2 (ACE2) receptor expressed on cell membranes. Patients with Alzheimer’s disease (AD) are more susceptible to SARS-CoV-2 infection and prone to severe clinical outcomes. Recent studies have revealed some common risk factors for AD and COVID-19. An understanding of the association between COVID-19 and AD and the potential related mechanisms may lead to the development of novel approaches to treating both diseases. In the present review, we first summarize the mechanisms by which SARS-CoV-2 invades the central nervous system (CNS) and then discuss the associations and potential shared key factors between COVID-19 and AD, with a focus on the ACE2 receptor, apolipoprotein E (APOE) genotype, age, and neuroinflammation.

Challenges in the Detection of SARS-CoV-2: Evolution of the Lateral Flow Immunoassay as a Valuable Tool for Viral Diagnosis

SARS-CoV-2 is an emerging infectious disease of zoonotic origin that caused the coronavirus disease in late 2019 and triggered a pandemic that has severely affected human health and caused millions of deaths. Early and massive diagnosis of SARS-CoV-2 infected patients is the key to preventing the spread of the virus and controlling the outbreak. Lateral flow immunoassays (LFIA) are the simplest biosensors. These devices are clinical diagnostic tools that can detect various analytes, including viruses and antibodies, with high sensitivity and specificity. This review summarizes the advantages, limitations, and evolution of LFIA during the SARS-CoV-2 pandemic and the challenges of improving these diagnostic devices.

3D Lung Tissue Models for Studies on SARS-CoV-2 Pathophysiology and Therapeutics

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causing the coronavirus disease 2019 (COVID-19), has provoked more than six million deaths worldwide and continues to pose a major threat to global health. Enormous efforts have been made by researchers around the world to elucidate COVID-19 pathophysiology, design efficacious therapy and develop new vaccines to control the pandemic. To this end, experimental models are essential. While animal models and conventional cell cultures have been widely utilized during these research endeavors, they often do not adequately reflect the human responses to SARS-CoV-2 infection. Therefore, models that emulate with high fidelity the SARS-CoV-2 infection in human organs are needed for discovering new antiviral drugs and vaccines against COVID-19. Three-dimensional (3D) cell cultures, such as lung organoids and bioengineered organs-on-chips, are emerging as crucial tools for research on respiratory diseases. The lung airway, small airway and alveolus organ chips have been successfully used for studies on lung response to infection by various pathogens, including corona and influenza A viruses. In this review, we provide an overview of these new tools and their use in studies on COVID-19 pathogenesis and drug testing. We also discuss the limitations of the existing models and indicate some improvements for their use in research against COVID-19 as well as future emerging epidemics.

Intratumoral Heterogeneity and Immune Modulation in Lung Adenocarcinoma in Female Smokers and Never Smokers

SIGNIFICANCE

Single-cell analysis of healthy lung tissue and lung cancer reveals distinct tumor cell populations, including cells with differential immune modulating capacity between smokers and never smokers, which could guide future therapeutic strategies.

Expression of SARS-CoV-2-Related Surface Proteins in Non-Small-Cell Lung Cancer Patients and the Influence of Standard of Care Therapy

Simple Summary

SARS-CoV-2 is a respiratory virus that uses ACE2 for host cell entry and the spike protein is primed by, among others, TMPRSS2 and FURIN. The goal of this study was to determine in which non-small-cell lung cancer (NSCLC) patients these proteins are expressed on the membrane of the lung cancer cells and in which patients this increased ACE2 expression results in higher levels of soluble (s)ACE2 in their serum. In addition, we studied the influence of standard of care (SOC) therapies on sACE2 levels. Membranous (m)ACE2 was co-expressed with mFURIN and/or mTMPRSS2 in 16% of the NSCLC patients, and mACE2 and sACE2 were more frequently expressed in mutant EGFR patients but not mutant-KRAS patients. Importantly, systemic SOC therapies did not result in increased sACE2 levels. This indicates that cancer cells can be infected by SARS-CoV-2 in these patients, as well as that soluble ACE2 could impact the course of COVID-19.

Abstract

In this study, we aimed to study the expression of SARS-CoV-2-related surface proteins in non-small-cell lung cancer (NSCLC) cells and identify clinicopathological characteristics that are related to increased membranous (m)ACE2 protein expression and soluble (s)ACE2 levels, with a particular focus on standard of care (SOC) therapies. ACE2 (n = 107), TMPRSS2, and FURIN (n = 38) protein expression was determined by immunohistochemical (IHC) analysis in NSCLC patients. sACE2 levels (n = 64) were determined in the serum of lung cancer patients collected before, during, or after treatment with SOC therapies. Finally, the TCGA lung adenocarcinoma (LUAD) database was consulted to study the expression of ACE2 in EGFR- and KRAS-mutant samples and ACE2 expression was correlated with EGFR/HER, RAS, BRAF, ROS1, ALK, and MET mRNA expression. Membranous (m)ACE2 was found to be co-expressed with mFURIN and/or mTMPRSS2 in 16% of the NSCLC samples and limited to the adenocarcinoma subtype. TMPRSS2 showed predominantly atypical cytoplasmic expression. mACE2 and sACE2 were more frequently expressed in mutant EGFR patients, but not mutant-KRAS patients. A significant difference was observed in sACE2 for patients treated with targeted therapies, but not for chemo- and immunotherapy. In the TCGA LUAD cohort, ACE2 expression was significantly higher in EGFR-mutant patients and significantly lower in KRAS-mutant patients. Finally, ACE2 expression was positively correlated with ERBB2-4 and ROS1 expression and inversely correlated with KRAS, NRAS, HRAS, and MET mRNA expression. We identified a role for EGFR pathway activation in the expression of mACE2 in NSCLC cells, associated with increased sACE2 levels in patients. Therefore, it is of great interest to study SARS-CoV-2-infected EGFR-mutated NSCLC patients in greater depth in order to obtain a better understanding of how mACE2, sACE2, and SOC TKIs can affect the course of COVID-19.