Targeting Lipid Rafts-A Potential Therapy for COVID-19

Membrane Lipid Nanodomains Modulate HCN Pacemaker Channels in Nociceptor DRG Neurons

Cell membranes consist of heterogeneous lipid nanodomains that influence key cellular processes. Using FRET-based fluorescent assays and fluorescence lifetime imaging microscopy (FLIM), we found that the dimension of cholesterol-enriched ordered membrane domains (OMD) varies considerably, depending on specific cell types. Particularly, nociceptor dorsal root ganglion (DRG) neurons exhibit large OMDs. Disruption of OMDs potentiated action potential firing in nociceptor DRG neurons and facilitated the opening of native hyperpolarization-activated cyclic nucleotide-gated (HCN) pacemaker channels. This increased neuronal firing is partially due to an increased open probability and altered gating kinetics of HCN channels. The gating effect on HCN channels was likely due to a direct modulation of their voltage sensors by OMDs. In animal models of neuropathic pain, we observed reduced OMD size and a loss of HCN channel localization within OMDs. Additionally, cholesterol supplementation inhibited HCN channels and reduced neuronal hyperexcitability in pain models. These findings suggest that disturbances in lipid nanodomains play a critical role in regulating HCN channels within nociceptor DRG neurons, influencing pain modulation.

MβCD inhibits SFTSV entry by disrupting lipid raft structure of the host cells

Severe fever with thrombocytopenia syndrome virus (SFTSV), recently named as Dabie bandavirus, belongs to the family Phenuiviridae of the order Bunyavirales, is a newly-identified bunyavirus with a case fatality rate of up to 30%, posing a serious threat to public health. Lipid rafts on plasm membranes are important for the entry of enveloped viruses; however, the role of lipid rafts in bunyavirus entry remains unclear. In this study, we found that methyl-beta-cyclodextrin (MβCD), a drug that disrupts cholesterol in lipid rafts of cell membranes, inhibits SFTSV infection. Additionally, there is a back-complementary effect of SFTSV infection upon the addition of cholesterol. Moreover, the concentration of SFTSV particles in lipid rafts during entry directly indicated the role of lipid rafts as a gateway, whereas MβCD could inhibit SFTSV entry by affecting the structure of lipid rafts. In an in vivo study, MβCD also reduced the susceptibility of mice to SFTSV infection. Our results suggest that SFTSV can interact with Talin1 proteins on lipid rafts to enter host cells by endocytosis of lipid rafts and reveal the potential therapeutic value of MβCD for SFTSV infection.

Mass spectrometric approaches in discovering lipid biomarkers for COVID-19 by lipidomics: Future challenges and perspectives

Coronavirus disease 2019 (COVID-19) has emerged as a global health threat and has rapidly spread worldwide. Significant changes in the lipid profile before and after COVID-19 confirmed the significance of lipid metabolism in regulating the response to viral infection. Therefore, understanding the role of lipid metabolism may facilitate the development of new therapeutics for COVID-19. Owing to their high sensitivity and accuracy, mass spectrometry (MS)-based methods are widely used for rapidly identifying and quantifying of thousands of lipid species present in a small amount of sample. To enhance the capabilities of MS for the qualitative and quantitative analysis of lipids, different platforms have been combined to cover a wide range of lipidomes with high sensitivity, specificity, and accuracy. Currently, MS-based technologies are being established as efficient methods for discovering potential diagnostic biomarkers for COVID-19 and related diseases. As the lipidome of the host cell is drastically affected by the viral replication process, investigating lipid profile alterations in patients with COVID-19 and targeting lipid metabolism pathways are considered to be crucial steps in host-directed drug targeting to develop better therapeutic strategies. This review summarizes various MS-based strategies that have been developed for lipidomic analyzes and biomarker discoveries to combat COVID-19 by integrating various other potential approaches using different human samples. Furthermore, this review discusses the challenges in using MS technologies and future perspectives in terms of drug discovery and diagnosis of COVID-19.

SARS-CoV-2-associated lymphopenia: possible mechanisms and the role of CD147

T lymphocytes play a primary role in the adaptive antiviral immunity. Both lymphocytosis and lymphopenia were found to be associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). While lymphocytosis indicates an active anti-viral response, lymphopenia is a sign of poor prognosis. T-cells, in essence, rarely express ACE2 receptors, making the cause of cell depletion enigmatic. Moreover, emerging strains posed an immunological challenge, potentially alarming for the next pandemic. Herein, we review how possible indirect and direct key mechanisms could contribute to SARS-CoV-2-associated-lymphopenia. The fundamental mechanism is the inflammatory cytokine storm elicited by viral infection, which alters the host cell metabolism into a more acidic state. This "hyperlactic acidemia" together with the cytokine storm suppresses T-cell proliferation and triggers intrinsic/extrinsic apoptosis. SARS-CoV-2 infection also results in a shift from steady-state hematopoiesis to stress hematopoiesis. Even with low ACE2 expression, the presence of cholesterol-rich lipid rafts on activated T-cells may enhance viral entry and syncytia formation. Finally, direct viral infection of lymphocytes may indicate the participation of other receptors or auxiliary proteins on T-cells, that can work alone or in concert with other mechanisms. Therefore, we address the role of CD147-a novel route-for SARS-CoV-2 and its new variants. CD147 is not only expressed on T-cells, but it also interacts with other co-partners to orchestrate various biological processes. Given these features, CD147 is an appealing candidate for viral pathogenicity. Understanding the molecular and cellular mechanisms behind SARS-CoV-2-associated-lymphopenia will aid in the discovery of potential therapeutic targets to improve the resilience of our immune system against this rapidly evolving virus.

Research Advances on the Role of Lipids in the Life Cycle of Human Coronaviruses

Coronaviruses (CoVs) are emerging pathogens with a significant potential to cause life-threatening harm to human health. Since the beginning of the 21st century, three highly pathogenic and transmissible human CoVs have emerged, triggering epidemics and posing major threats to global public health. CoVs are enveloped viruses encased in a lipid bilayer. As fundamental components of cells, lipids can play an integral role in many physiological processes, which have been reported to play important roles in the life cycle of CoVs, including viral entry, uncoating, replication, assembly, and release. Therefore, research on the role of lipids in the CoV life cycle can provide a basis for a better understanding of the infection mechanism of CoVs and provide lipid targets for the development of new antiviral strategies. In this review, research advances on the role of lipids in different stages of viral infection and the possible targets of lipids that interfere with the viral life cycle are discussed.

Mapping the Lipid Signatures in COVID-19 Infection: Diagnostic and Therapeutic Solutions

The COVID-19 pandemic ignited research centered around the identification of robust biomarkers and therapeutic targets. SARS-CoV-2, the virus responsible, hijacks the metabolic machinery of the host cells. It relies on lipids and lipoproteins of host cells for entry, trafficking, immune evasion, viral replication, and exocytosis. The infection causes host cell lipid metabolic remodelling. Targeting lipid-based processes is thus a promising strategy for countering COVID-19. Here, we review the role of lipids in the different steps of the SARS-CoV-2 pathogenesis and identify lipid-centric targetable avenues. We discuss lipidome changes in infected patients and their relevance as potential clinical diagnostic or prognostic biomarkers. We summarize the emerging direct and indirect therapeutic approaches for targeting COVID-19 using lipid-inspired approaches. Given that viral protein-targeted therapies may become less effective due to mutations in emerging SARS-CoV-2 variants, lipid-inspired interventions may provide additional and perhaps better means of combating this and future pandemics.

Direct regulation of the voltage sensor of HCN channels by membrane lipid compartmentalization

Ion channels function within a membrane environment characterized by dynamic lipid compartmentalization. Limited knowledge exists regarding the response of voltage-gated ion channels to transmembrane potential within distinct membrane compartments. By leveraging fluorescence lifetime imaging microscopy (FLIM) and Förster resonance energy transfer (FRET), we visualized the localization of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in membrane domains. HCN4 exhibits a greater propensity for incorporation into ordered lipid domains compared to HCN1. To investigate the conformational changes of the S4 helix voltage sensor of HCN channels, we used dual stop-codon suppression to incorporate different noncanonical amino acids, orthogonal click chemistry for site-specific fluorescence labeling, and transition metal FLIM-FRET. Remarkably, altered FRET levels were observed between VSD sites within HCN channels upon disruption of membrane domains. We propose that the voltage-sensor rearrangements, directly influenced by membrane lipid domains, can explain the heightened activity of pacemaker HCN channels when localized in cholesterol-poor, disordered lipid domains, leading to membrane hyperexcitability and diseases.

Spotlight on contributory role of host immunogenetic profiling in SARS-CoV-2 infection: Susceptibility, severity, mortality, and vaccine effectiveness

BACKGROUND

The SARS-CoV-2 virus has spread continuously worldwide, characterized by various clinical symptoms. The immune system responds to SARS-CoV-2 infection by producing Abs and secreting cytokines. Recently, numerous studies have highlighted that immunogenetic factors perform a putative role in COVID-19 pathogenesis and implicate vaccination effectiveness.

AIM

This review summarizes the relevant articles and evaluates the significance of mutation and polymorphism in immune-related genes regarding susceptibility, severity, mortality, and vaccination effectiveness of COVID-19. Furthermore, the correlation between host immunogenetic and SARS-CoV-2 reinfection is discussed.

METHOD

A comprehensive search was conducted to identify relevant articles using five databases until January 2023, which resulted in 105 total articles.

KEY FINDINGS

Taken to gather this review summarized that: (a) there is a plausible correlation between immune-related genes and COVID-19 outcomes, (b) the HLAs, cytokines, chemokines, and other immune-related genes expression profiles can be a prognostic factor in COVID-19-infected patients, and (c) polymorphisms in immune-related genes have been associated with the effectiveness of vaccination.

SIGNIFICANCE

Regarding the importance of mutation and polymorphisms in immune-related genes in COVID-19 outcomes, modulating candidate genes is expected to help clinical decisions, patient outcomes management, and innovative therapeutic approach development. In addition, the manipulation of host immunogenetics is hypothesized to induce more robust cellular and humoral immune responses, effectively increase the efficacy of vaccines, and subsequently reduce the incidence rates of reinfection-associated COVID-19.

Metabolic alterations upon SARS-CoV-2 infection and potential therapeutic targets against coronavirus infection

The coronavirus disease 2019 (COVID-19) caused by coronavirus SARS-CoV-2 infection has become a global pandemic due to the high viral transmissibility and pathogenesis, bringing enormous burden to our society. Most patients infected by SARS-CoV-2 are asymptomatic or have mild symptoms. Although only a small proportion of patients progressed to severe COVID-19 with symptoms including acute respiratory distress syndrome (ARDS), disseminated coagulopathy, and cardiovascular disorders, severe COVID-19 is accompanied by high mortality rates with near 7 million deaths. Nowadays, effective therapeutic patterns for severe COVID-19 are still lacking. It has been extensively reported that host metabolism plays essential roles in various physiological processes during virus infection. Many viruses manipulate host metabolism to avoid immunity, facilitate their own replication, or to initiate pathological response. Targeting the interaction between SARS-CoV-2 and host metabolism holds promise for developing therapeutic strategies. In this review, we summarize and discuss recent studies dedicated to uncovering the role of host metabolism during the life cycle of SARS-CoV-2 in aspects of entry, replication, assembly, and pathogenesis with an emphasis on glucose metabolism and lipid metabolism. Microbiota and long COVID-19 are also discussed. Ultimately, we recapitulate metabolism-modulating drugs repurposed for COVID-19 including statins, ASM inhibitors, NSAIDs, Montelukast, omega-3 fatty acids, 2-DG, and metformin.

ARF6 is a host factor for SARS-CoV-2 infection in vitro

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a newly emerged beta-coronavirus that enter cells via two routes, direct fusion at the plasma membrane or endocytosis followed by fusion with the late endosome/lysosome. While the viral receptor, ACE2, multiple entry factors and the mechanism of fusion of the virus at the plasma membrane have been investigated extensively, viral entry via the endocytic pathway is less understood. By using a human hepatocarcinoma cell line, Huh-7, which is resistant to the antiviral action of the TMPRSS2 inhibitor camostat, we discovered that SARS-CoV-2 entry is not dependent on dynamin but on cholesterol. ADP-ribosylation factor 6 (ARF6) has been described as a host factor for SARS-CoV-2 replication and is involved in the entry and infection of several pathogenic viruses. Using CRISPR/Cas9 genetic deletion, a modest reduction in SARS-CoV-2 uptake and infection in Huh-7 was observed. In addition, pharmacological inhibition of ARF6 with the small molecule NAV-2729 showed a dose-dependent reduction of viral infection. Importantly, NAV-2729 also reduced SARS-CoV-2 viral loads in more physiological models of infection: Calu-3 cells and kidney organoids. This highlighted a role for ARF6 in multiple cell contexts. Together, these experiments point to ARF6 as a putative target to develop antiviral strategies against SARS-CoV-2.

An integrated in-silico Pharmaco-BioInformatics approaches to identify synergistic effects of COVID-19 to HIV patients

BACKGROUND

With high inflammatory states from both COVID-19 and HIV conditions further result in complications. The ongoing confrontation between these two viral infections can be avoided by adopting suitable management measures.

PURPOSE

The aim of this study was to figure out the pharmacological mechanism behind apigenin's role in the synergetic effects of COVID-19 to the progression of HIV patients.

METHOD

We employed computer-aided methods to uncover similar biological targets and signaling pathways associated with COVID-19 and HIV, along with bioinformatics and network pharmacology techniques to assess the synergetic effects of apigenin on COVID-19 to the progression of HIV, as well as pharmacokinetics analysis to examine apigenin's safety in the human body.

RESULT

Stress-responsive, membrane receptor, and induction pathways were mostly involved in gene ontology (GO) pathways, whereas apoptosis and inflammatory pathways were significantly associated in the Kyoto encyclopedia of genes and genomes (KEGG). The top 20 hub genes were detected utilizing the shortest path ranked by degree method and protein-protein interaction (PPI), as well as molecular docking and molecular dynamics simulation were performed, revealing apigenin's strong interaction with hub proteins (MAPK3, RELA, MAPK1, EP300, and AKT1). Moreover, the pharmacokinetic features of apigenin revealed that it is an effective therapeutic agent with minimal adverse effects, for instance, hepatoxicity.

CONCLUSION

Synergetic effects of COVID-19 on the progression of HIV may still be a danger to global public health. Consequently, advanced solutions are required to give valid information regarding apigenin as a suitable therapeutic agent for the management of COVID-19 and HIV synergetic effects. However, the findings have yet to be confirmed in patients, suggesting more in vitro and in vivo studies.

ARF6 is a host factor for SARS-CoV-2 infection in vitro

SARS-CoV-2 is a newly emerged beta-coronavirus that enter cells via two routes, direct fusion at the plasma membrane or endocytosis followed by fusion with the late endosome/lysosome. While the viral receptor, ACE2, multiple entry factors, and the mechanism of fusion of the virus at the plasma membrane have been extensively investigated, viral entry via the endocytic pathway is less understood. By using a human hepatocarcinoma cell line, Huh-7, which is resistant to the antiviral action of the TMPRSS2 inhibitor camostat, we discovered that SARS-CoV-2 entry is not dependent on dynamin but dependent on cholesterol. ADP-ribosylation factor 6 (ARF6) has been described as a host factor for SARS-CoV-2 replication and it is involved in the entry and infection of several pathogenic viruses. Using CRISPR-Cas9 genetic deletion, we observed that ARF6 is important for SARS-CoV-2 uptake and infection in Huh-7. This finding was corroborated using a pharmacologic inhibitor, whereby the ARF6 inhibitor NAV-2729 showed a dose-dependent inhibition of viral infection. Importantly, NAV-2729 reduced SARS-CoV-2 viral loads also in more physiologic models of infection: Calu-3 and kidney organoids. This highlighted the importance of ARF6 in multiple cell contexts. Together, these experiments points to ARF6 as a putative target to develop antiviral strategies against SARS-CoV-2.

CLN7/MFSD8 may be an important factor for SARS-CoV-2 cell entry

The SARS-CoV-2 virus has triggered a worldwide pandemic. According to the BioGrid database, CLN7 (MFSD8) is thought to interact with several viral proteins. The aim of this work was to investigate a possible involvement of CLN7 in the infection process. Experiments on a CLN7-deficient HEK293T cell line exhibited a 90% reduced viral load compared to wild-type cells. This observation may be linked to the finding that CLN7 ko cells have a significantly reduced GM1 content in their cell membrane. GM1 is found highly enriched in lipid rafts, which are thought to play an important role in SARS-CoV-2 infection. In contrast, overexpression of CLN7 led to an increase in viral load. This study provides evidence that CLN7 is involved in SARS-CoV-2 infection. This makes it a potential pharmacological target for drug development against COVID-19. Furthermore, it provides insights into the physiological function of CLN7 where still only little is known about.

Dual-targeting cyclic peptides of receptor-binding domain (RBD) and main protease (Mpro) as potential drug leads for the treatment of SARS-CoV-2 infection

The receptor-binding domain (RBD) and the main protease (Mpro) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) play a crucial role in the entry and replication of viral particles, and co-targeting both of them could be an attractive approach for the treatment of SARS-CoV-2 infection by setting up a "double lock" in the viral lifecycle. However, few dual RBD/Mpro-targeting agents have been reported. Here, four novel RBD/Mpro dual-targeting peptides, termed as MRs 1-4, were discovered by an integrated virtual screening scheme combining molecular docking-based screening and molecular dynamics simulation. All of them possessed nanomolar binding affinities to both RBD and Mpro ranging from 14.4 to 39.2 nM and 22.5-40.4 nM, respectively. Further pseudovirus infection assay revealed that the four selected peptides showed >50% inhibition against SARS-CoV-2 pseudovirus at a concentration of 5 µM without significant cytotoxicity to host cells. This study leads to the identification of a class of dual RBD/Mpro-targeting agents, which may be developed as potential and effective SARS-CoV-2 therapeutics.

COVID-19 metabolism: Mechanisms and therapeutic targets

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) dysregulates antiviral signaling, immune response, and cell metabolism in human body. Viral genome and proteins hijack host metabolic network to support viral biogenesis and propagation. However, the regulatory mechanism of SARS-CoV-2-induced metabolic dysfunction has not been elucidated until recently. Multiomic studies of coronavirus disease 2019 (COVID-19) revealed an intensive interaction between host metabolic regulators and viral proteins. SARS-CoV-2 deregulated cellular metabolism in blood, intestine, liver, pancreas, fat, and immune cells. Host metabolism supported almost every stage of viral lifecycle. Strikingly, viral proteins were found to interact with metabolic enzymes in different cellular compartments. Biochemical and genetic assays also identified key regulatory nodes and metabolic dependencies of viral replication. Of note, cholesterol metabolism, lipid metabolism, and glucose metabolism are broadly involved in viral lifecycle. Here, we summarized the current understanding of the hallmarks of COVID-19 metabolism. SARS-CoV-2 infection remodels host cell metabolism, which in turn modulates viral biogenesis and replication. Remodeling of host metabolism creates metabolic vulnerability of SARS-CoV-2 replication, which could be explored to uncover new therapeutic targets. The efficacy of metabolic inhibitors against COVID-19 is under investigation in several clinical trials. Ultimately, the knowledge of SARS-CoV-2-induced metabolic reprogramming would accelerate drug repurposing or screening to combat the COVID-19 pandemic.

Nanoscale Technologies in the Fight against COVID-19: From Innovative Nanomaterials to Computer-Aided Discovery of Potential Antiviral Plant-Derived Drugs

The last few years have increasingly emphasized the need to develop new active antiviral products obtained from artificial synthesis processes using nanomaterials, but also derived from natural matrices. At the same time, advanced computational approaches have found themselves fundamental in the repurposing of active therapeutics or for reducing the very long developing phases of new drugs discovery, which represents a real limitation, especially in the case of pandemics. The first part of the review is focused on the most innovative nanomaterials promising both in the field of therapeutic agents, as well as measures to control virus spread (i.e., innovative antiviral textiles). The second part of the review aims to show how computer-aided technologies can allow us to identify, in a rapid and therefore constantly updated way, plant-derived molecules (i.e., those included in terpenoids) potentially able to efficiently interact with SARS-CoV-2 cell penetration pathways.

Implications of COVID-19 to Stroke Medicine: An Epidemiological and Pathophysiological Perspective

The neurological complications of Coronavirus 2019 (COVID-19) including stroke have been documented in the recent literature. COVID-19-related inflammation is suggested to contribute to both a hypercoagulable state and haemorrhagic transformation, including in younger individuals. COVID-19 is associated with a heightened risk of ischaemic stroke. Haemorrhagic stroke in COVID-19 patients is associated with increased morbidity and mortality. Cerebral venous sinus thrombosis (CVST) accounts for <1% of stroke cases in the general population but has come to heightened public attention due to the increased risk associated with adenoviral COVID-19 vaccines. However, recent evidence suggests the prevalence of stroke is less in vaccinated individuals than in unvaccinated COVID-19 patients. This review evaluates the current evidence of COVID-19-related ischaemic and haemorrhagic stroke, with a focus on current epidemiology and inflammatory-linked pathophysiology in the field of vascular neurology and stroke medicine.

Lipid rafts as viral entry routes and immune platforms: A double-edged sword in SARS-CoV-2 infection?

Lipid rafts are nanoscopic compartments of cell membranes that serve a variety of biological functions. They play a crucial role in viral infections, as enveloped viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can exploit rafts to enter or quit target cells. On the other hand, lipid rafts contribute to the formation of immune synapses and their proper functioning is a prerequisite for adequate immune response and viral clearance. In this narrative review we dissect the panorama focusing on this singular aspect of cell biology in the context of SARS-CoV-2 infection and therapy. A lipid raft-mediated mechanism can be hypothesized for many drugs recommended or considered for the treatment of SARS-CoV-2 infection, such as glucocorticoids, antimalarials, immunosuppressants and antiviral agents. Furthermore, the additional use of lipid-lowering agents, like statins, may affect the lipid composition of membrane rafts and thus influence the processes occurring in these compartments. The combination of drugs acting on lipid rafts may be successful in the treatment of more severe forms of the disease and should be reserved for further investigation.

Ceramide Aminoethylphosphonate as a New Molecular Target for Pore-Forming Aegerolysin-Based Protein Complexes

Ostreolysin A6 (OlyA6) is a 15 kDa protein produced by the oyster mushroom (Pleurotus ostreatus). It belongs to the aegerolysin family of proteins and binds with high affinity to the insect-specific membrane sphingolipid, ceramide phosphoethanolamine (CPE). In concert with its partnering protein with the membrane-attack-complex/perforin domain, pleurotolysin B (PlyB), OlyA6 can form bicomponent 13-meric transmembrane pores in artificial and biological membranes containing the aegerolysin lipid receptor, CPE. This pore formation is the main underlying molecular mechanism of potent and selective insecticidal activity of OlyA6/PlyB complexes against two economically important coleopteran plant pests: the western corn rootworm and the Colorado potato beetle. In contrast to insects, the main sphingolipid in cell membranes of marine invertebrates (i.e., molluscs and cnidarians) is ceramide aminoethylphosphonate (CAEP), a CPE analogue built on a phosphono rather than the usual phosphate group in its polar head. Our targeted lipidomic analyses of the immune cells (hemocytes) of the marine bivalve, the mussel Mytilus galloprovincialis, confirmed the presence of 29.0 mol% CAEP followed by 36.4 mol% of phosphatidylcholine and 34.6 mol% of phosphatidylethanolamine. Further experiments showed the potent binding of OlyA6 to artificial lipid vesicles supplemented with mussel CAEP, and strong lysis of these vesicles by the OlyA6/PlyB mixture. In Mytilus haemocytes, short term exposure (max. 1 h) to the OlyA6/PlyB mixture induced lysosomal membrane destabilization, decreased phagocytic activity, increased Annexin V binding and oxyradical production, and decreased levels of reduced glutathione, indicating rapid damage of endo-lysosomal and plasma membranes and oxidative stress. Our data suggest CAEP as a novel high-affinity receptor for OlyA6 and a target for cytolytic OlyA6/PlyB complexes.

Cell surface detection of vimentin, ACE2 and SARS-CoV-2 Spike proteins reveals selective colocalization at primary cilia

The SARS-CoV-2 Spike protein mediates docking of the virus onto cells prior to viral invasion. Several cellular receptors facilitate SARS-CoV-2 Spike docking at the cell surface, of which ACE2 plays a key role in many cell types. The intermediate filament protein vimentin has been reported to be present at the surface of certain cells and act as a co-receptor for several viruses; furthermore, its potential involvement in interactions with Spike proteins has been proposed. Nevertheless, the potential colocalization of vimentin with Spike and its receptors on the cell surface has not been explored. Here we have assessed the binding of Spike protein constructs to several cell types. Incubation of cells with tagged Spike S or Spike S1 subunit led to discrete dotted patterns at the cell surface, which consistently colocalized with endogenous ACE2, but sparsely with a lipid raft marker. Vimentin immunoreactivity mostly appeared as spots or patches unevenly distributed at the surface of diverse cell types. Of note, vimentin could also be detected in extracellular particles and in the cytoplasm underlying areas of compromised plasma membrane. Interestingly, although overall colocalization of vimentin-positive spots with ACE2 or Spike was moderate, a selective enrichment of the three proteins was detected at elongated structures, positive for acetylated tubulin and ARL13B. These structures, consistent with primary cilia, concentrated Spike binding at the top of the cells. Our results suggest that a vimentin-Spike interaction could occur at selective locations of the cell surface, including ciliated structures, which can act as platforms for SARS-CoV-2 docking.

Spike protein of SARS-CoV-2 suppresses gonadotrophin secretion from bovine anterior pituitaries

Coronavirus disease (COVID-19), the ongoing global pandemic, is caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Recent evidence shows that the virus utilizes angiotensin-converting enzyme 2 (ACE2) as a spike protein receptor for entry into target host cells. The bovine ACE2 contains key residues for binding to the spike protein receptor-binding domain. This study evaluated the hypothesis that bovine gonadotroph expresses ACE2, and spike protein suppresses luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion from cultured bovine anterior pituitary (AP) cells. ACE2 mRNA expression and ACE2 protein expression were detected in the bovine AP cells using reverse transcription PCR and western blot analysis. Immunofluorescence microscopy analysis with the anti-ACE2 antibody revealed the co-localization of ACE2 and gonadotropin-releasing hormone (GnRH) receptor on the gonadotroph plasma membrane. Approximately 90% of GnRH receptor-positive cells expressed ACE2, and approximately 46% of ACE2-positive cells expressed the GnRH receptor. We cultured bovine AP cells for 3.5 days and treated them with increasing concentrations (0, 0.07, 0.7, or 7 pM) of recombinant spike protein having both S1 and S2 regions. The spike protein (0.07-7 pM) suppressed both basal and GnRH-induced LH secretion (P < 0.05). Spike protein (0.7-7 pM) suppressed GnRH-induced (P < 0.05), but not basal FSH secretion. In contrast, pre-treatment with ERK 1/2/5 inhibitor (U0126) partially restored the GnRH-induced LH and FSH secretion from the spike protein suppression. Collectively, the results indicate that gonadotrophs express ACE2, a receptor for coronavirus 2 spike protein, which in turn suppresses LH and FSH secretion from AP cells.

Coronary Stent Thrombosis in COVID-19 Patients: A Systematic Review of Cases Reported Worldwide

Approximately 5 million percutaneous coronary interventions are performed worldwide annually. Therefore, stent-related complications pose a serious public health concern. Stent thrombosis, although rare, is usually catastrophic, often associated with extensive myocardial infarction or death. Because little progress has been made in outcomes following stent thrombosis, ongoing research is focusing on further understanding the predictors as well as frequency and timing in various patient subgroups. Coronavirus disease-2019 (COVID-19), a viral illness caused by the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), activates inflammatory mechanisms that potentially create a prothrombotic environment and increases the risk of local micro thromboembolism and all types of stent thrombosis. In-stent thrombosis occurrence increased during the COVID-19 pandemic, however, there is still lack of comprehensive studies describing this population. This review and worldwide analysis of coronary stent thrombosis cases related to COVID-19 summarizes all available data.

Role of Lipid Rafts in Pathogen-Host Interaction - A Mini Review

Lipid rafts, also known as microdomains, are important components of cell membranes and are enriched in cholesterol, glycophospholipids and receptors. They are involved in various essential cellular processes, including endocytosis, exocytosis and cellular signaling. Receptors are concentrated at lipid rafts, through which cellular signaling can be transmitted. Pathogens exploit these signaling mechanisms to enter cells, proliferate and egress. However, lipid rafts also play an important role in initiating antimicrobial responses by sensing pathogens via clustered pathogen-sensing receptors and triggering downstream signaling events such as programmed cell death or cytokine production for pathogen clearance. In this review, we discuss how both host and pathogens use lipid rafts and associated proteins in an arms race to survive. Special attention is given to the involvement of the major vault protein, the main constituent of a ribonucleoprotein complex, which is enriched in lipid rafts upon infection with vaccinia virus.

Atorvastatin versus placebo in patients with covid-19 in intensive care: randomized controlled trial

OBJECTIVE

To assess the effect of statin treatment versus placebo on clinical outcomes in patients with covid-19 admitted to the intensive care unit (ICU).

DESIGN

INSPIRATION/INSPIRATION-S was a multicenter, randomized controlled trial with a 2×2 factorial design. Results for the anticoagulation randomization have been reported previously. Results for the double blind randomization to atorvastatin versus placebo are reported here.

SETTING

11 hospitals in Iran.

PARTICIPANTS

Adults aged ≥18 years with covid-19 admitted to the ICU.

INTERVENTION

Atorvastatin 20 mg orally once daily versus placebo, to be continued for 30 days from randomization irrespective of hospital discharge status.

MAIN OUTCOME MEASURES

The primary efficacy outcome was a composite of venous or arterial thrombosis, treatment with extracorporeal membrane oxygenation, or all cause mortality within 30 days from randomization. Prespecified safety outcomes included increase in liver enzyme levels more than three times the upper limit of normal and clinically diagnosed myopathy. A clinical events committee blinded to treatment assignment adjudicated the efficacy and safety outcomes.

RESULTS

Of 605 patients randomized between 29 July 2020 and 4 April 2021 for statin randomization in the INSPIRATION-S trial, 343 were co-randomized to intermediate dose versus standard dose prophylactic anticoagulation with heparin based regimens, whereas 262 were randomized after completion of the anticoagulation study. 587 of the 605 participants were included in the primary analysis of INSPIRATION-S, reported here: 290 were assigned to atorvastatin and 297 to placebo (median age 57 years (interquartile range 45-68 years); 256 (44%) women). The primary outcome occurred in 95 (33%) patients assigned to atorvastatin and 108 (36%) assigned to placebo (odds ratio 0.84, 95% confidence interval 0.58 to 1.21). Death occurred in 90 (31%) patients in the atorvastatin group and 103 (35%) in the placebo group (odds ratio 0.84, 95% confidence interval 0.58 to 1.22). Rates for venous thromboembolism were 2% (n=6) in the atorvastatin group and 3% (n=9) in the placebo group (odds ratio 0.71, 95% confidence interval 0.24 to 2.06). Myopathy was not clinically diagnosed in either group. Liver enzyme levels were increased in five (2%) patients assigned to atorvastatin and six (2%) assigned to placebo (odds ratio 0.85, 95% confidence interval 0.25 to 2.81).

CONCLUSIONS

In adults with covid-19 admitted to the ICU, atorvastatin was not associated with a significant reduction in the composite of venous or arterial thrombosis, treatment with extracorporeal membrane oxygenation, or all cause mortality compared with placebo. Treatment was, however, found to be safe. As the overall event rates were lower than expected, a clinically important treatment effect cannot be excluded.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04486508.

Plasmalogen Loss in Sepsis and SARS-CoV-2 Infection

Plasmalogens are plasma-borne antioxidant phospholipid species that provide protection as cellular lipid components during cellular oxidative stress. In this study we investigated plasma plasmalogen levels in human sepsis as well as in rodent models of infection. In humans, levels of multiple plasmenylethanolamine molecular species were decreased in septic patient plasma compared to control subject plasma as well as an age-aligned control subject cohort. Additionally, lysoplasmenylcholine levels were significantly decreased in septic patients compared to the control cohorts. In contrast, plasma diacyl phosphatidylethanolamine and phosphatidylcholine levels were elevated in septic patients. Lipid changes were also determined in rats subjected to cecal slurry sepsis. Plasma plasmenylcholine, plasmenylethanolamine, and lysoplasmenylcholine levels were decreased while diacyl phosphatidylethanolamine levels were increased in septic rats compared to control treated rats. Kidney levels of lysoplasmenylcholine as well as plasmenylethanolamine molecular species were decreased in septic rats. Interestingly, liver plasmenylcholine and plasmenylethanolamine levels were increased in septic rats. Since COVID-19 is associated with sepsis-like acute respiratory distress syndrome and oxidative stress, plasmalogen levels were also determined in a mouse model of COVID-19 (intranasal inoculation of K18 mice with SARS-CoV-2). 3 days following infection, lung infection was confirmed as well as cytokine expression in the lung. Multiple molecular species of lung plasmenylcholine and plasmenylethanolamine were decreased in infected mice. In contrast, the predominant lung phospholipid, dipalmitoyl phosphatidylcholine, was not decreased following SARS-CoV-2 infection. Additionally total plasmenylcholine levels were decreased in the plasma of SARS-CoV-2 infected mice. Collectively, these data demonstrate the loss of plasmalogens during both sepsis and SARS-CoV-2 infection. This study also indicates plasma plasmalogens should be considered in future studies as biomarkers of infection and as prognostic indicators for sepsis and COVID-19 outcomes.

APOA1 Level is Negatively Correlated with the Severity of COVID-19

Objective

We used public data to analyze the proteomics, metabolomics and transcriptomics characteristics of COVID-19 patients to identify potential therapeutic targets. More importantly, we also collected clinical data for verification to make the analysis results more reliable.

Methods

Download the serum proteomics and metabolomics data of COVID-19 patients and describe their changes in serum proteins and metabolites, and use bioinformatics analysis methods to identify potential biomarkers and therapeutic targets. Finally, clinical data and experimental data of cell infection were combined for verification.

Results

It was found that the serum apolipoprotein A1 (APOA1) protein level in COVID-19 patients was down-regulated (log2FC = −0.39, false discovery rate (FDR) < 0.001), and the degree of reduction in the severe group was more significant (kruskal-test p = 2.5e-05). What is more, APOA1 was not only expressed lower in male patients (Wilcox-test p = 0.012), but also negatively correlated with C-reactive protein (CRP, r = −0.37, p = 0.019). The experiment data from SARS-CoV-2 infected cells further showed that the protein and transcript level of APOA1 gradually decreased as the infection time increased, and the transcription level (log₂FC = −8.3, FDR = 0.0015) was more down-regulated than protein level (log2FC = −0.95, FDR = 0.0014). More importantly, the collected clinical data also confirmed that APOA1 was down-regulated in COVID-19 patients (kruskal-test p = 0.001), and APOA1 levels are negatively correlated with IL6 (r = −0.396, p = 2.22e-07), D-dimers (DD, r = −0.262, p = 8.19e-04), prothrombin time (PT, r = −0.464, p = 6.68e-10) and thrombin time (TT, r = −0.279, p = 3.46e-04).

Conclusion

The degree of down-regulation of APOA1 is positively correlated with the severity of COVID-19, and the expression level of APOA1 is negatively correlated with CRP, IL6, DD, PT, TT, and positively correlated with HD and LDL. This indicates that APOA1 may be a key molecule in tandem acute inflammatory response, coagulation abnormalities and cholesterol metabolism disorder in COVID-19, and could be a potential therapeutic target.

Cholesterol-Rich Lipid Rafts as Platforms for SARS-CoV-2 Entry

Since its appearance, the Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2), the causal agent of Coronavirus Disease 2019 (COVID-19), represents a global problem for human health that involves the host lipid homeostasis. Regarding, lipid rafts are functional membrane microdomains with highly and tightly packed lipid molecules. These regions enriched in sphingolipids and cholesterol recruit and concentrate several receptors and molecules involved in pathogen recognition and cellular signaling. Cholesterol-rich lipid rafts have multiple functions for viral replication; however, their role in SARS-CoV-2 infection remains unclear. In this review, we discussed the novel evidence on the cholesterol-rich lipid rafts as a platform for SARS-CoV-2 entry, where receptors such as the angiotensin-converting enzyme-2 (ACE-2), heparan sulfate proteoglycans (HSPGs), human Toll-like receptors (TLRs), transmembrane serine proteases (TMPRSS), CD-147 and HDL-scavenger receptor B type 1 (SR-B1) are recruited for their interaction with the viral spike protein. FDA-approved drugs such as statins, metformin, hydroxychloroquine, and cyclodextrins (methyl-β-cyclodextrin) can disrupt cholesterol-rich lipid rafts to regulate key molecules in the immune signaling pathways triggered by SARS-CoV-2 infection. Taken together, better knowledge on cholesterol-rich lipid rafts in the SARS-CoV-2-host interactions will provide valuable insights into pathogenesis and the identification of novel therapeutic targets.

The ApoA-I mimetic peptide 4F attenuates in vitro replication of SARS-CoV-2, associated apoptosis, oxidative stress and inflammation in epithelial cells

An oral antiviral against SARS-CoV-2 that also attenuates inflammatory instigators of severe COVID-19 is not available to date. Herein, we show that the apoA-I mimetic peptide 4 F inhibits Spike mediated viral entry and has antiviral activity against SARS-CoV-2 in human lung epithelial Calu3 and Vero-E6 cells. In SARS-CoV-2 infected Calu3 cells, 4 F upregulated inducers of the interferon pathway such as MX-1 and Heme oxygenase 1 (HO-1) and downregulated mitochondrial reactive oxygen species (mito-ROS) and CD147, a host protein that mediates viral entry. 4 F also reduced associated cellular apoptosis and secretion of IL-6 in both SARS-CoV-2 infected Vero-E6 and Calu3 cells. Thus, 4 F attenuates in vitro SARS-CoV-2 replication, associated apoptosis in epithelial cells and secretion of IL-6, a major cytokine related to COVID-19 morbidity. Given established safety of 4 F in humans, clinical studies are warranted to establish 4 F as therapy for COVID-19.

Lipids in Pathophysiology and Development of the Membrane Lipid Therapy: New Bioactive Lipids

Membranes are mainly composed of a lipid bilayer and proteins, constituting a checkpoint for the entry and passage of signals and other molecules. Their composition can be modulated by diet, pathophysiological processes, and nutritional/pharmaceutical interventions. In addition to their use as an energy source, lipids have important structural and functional roles, e.g., fatty acyl moieties in phospholipids have distinct impacts on human health depending on their saturation, carbon length, and isometry. These and other membrane lipids have quite specific effects on the lipid bilayer structure, which regulates the interaction with signaling proteins. Alterations to lipids have been associated with important diseases, and, consequently, normalization of these alterations or regulatory interventions that control membrane lipid composition have therapeutic potential. This approach, termed membrane lipid therapy or membrane lipid replacement, has emerged as a novel technology platform for nutraceutical interventions and drug discovery. Several clinical trials and therapeutic products have validated this technology based on the understanding of membrane structure and function. The present review analyzes the molecular basis of this innovative approach, describing how membrane lipid composition and structure affects protein-lipid interactions, cell signaling, disease, and therapy (e.g., fatigue and cardiovascular, neurodegenerative, tumor, infectious diseases).

Investigating Lipid-Modulating Agents for Prevention or Treatment of COVID-19: JACC State-of-the-Art Review

Coronavirus disease-2019 (COVID-19) is associated with systemic inflammation, endothelial activation, and multiorgan manifestations. Lipid-modulating agents may be useful in treating patients with COVID-19. These agents may inhibit viral entry by lipid raft disruption or ameliorate the inflammatory response and endothelial activation. In addition, dyslipidemia with lower high-density lipoprotein cholesterol and higher triglyceride levels portend worse outcomes in patients with COVID-19. Upon a systematic search, 40 randomized controlled trials (RCTs) with lipid-modulating agents were identified, including 17 statin trials, 14 omega-3 fatty acids RCTs, 3 fibrate RCTs, 5 niacin RCTs, and 1 dalcetrapib RCT for the management or prevention of COVID-19. From these 40 RCTs, only 2 have reported preliminary results, and most others are ongoing. This paper summarizes the ongoing or completed RCTs of lipid-modulating agents in COVID-19 and the implications of these trials for patient management.

Severity of COVID-19 Patients Predicted by Serum Sphingolipids Signature

The reason behind the high inter-individual variability in response to SARS-CoV-2 infection and patient’s outcome is poorly understood. The present study targets the sphingolipid profile of twenty-four healthy controls and fifty-nine COVID-19 patients with different disease severity. Sera were analyzed by untargeted and targeted mass spectrometry and ELISA. Results indicated a progressive increase in dihydrosphingosine, dihydroceramides, ceramides, sphingosine, and a decrease in sphingosine-1-phosphate. These changes are associated with a serine palmitoyltransferase long chain base subunit 1 (SPTLC1) increase in relation to COVID-19 severity. Severe patients showed a decrease in sphingomyelins and a high level of acid sphingomyelinase (aSMase) that influences monosialodihexosyl ganglioside (GM3) C16:0 levels. Critical patients are characterized by high levels of dihydrosphingosine and dihydroceramide but not of glycosphingolipids. In severe and critical patients, unbalanced lipid metabolism induces lipid raft remodeling, leads to cell apoptosis and immunoescape, suggesting active sphingolipid participation in viral infection. Furthermore, results indicated that the sphingolipid and glycosphingolipid metabolic rewiring promoted by aSMase and GM3 is age-dependent but also characteristic of severe and critical patients influencing prognosis and increasing viral load. AUCs calculated from ROC curves indicated ceramides C16:0, C18:0, C24:1, sphingosine and SPTLC1 as putative biomarkers of disease evolution.

Compartmentalization of phosphatidylinositol 4,5-bisphosphate metabolism into plasma membrane liquid-ordered/raft domains

Possible segregation of plasma membrane (PM) phosphoinositide metabolism in membrane lipid domains is not fully understood. We exploited two differently lipidated peptide sequences, L10 and S15, to mark liquid-ordered, cholesterol-rich (L_o) and liquid-disordered, cholesterol-poor (L_d) domains of the PM, often called raft and nonraft domains, respectively. Imaging of the fluorescent labels verified that L10 segregated into cholesterol-rich L_o phases of cooled giant plasma-membrane vesicles (GPMVs), whereas S15 and the dye FAST DiI cosegregated into cholesterol-poor L_d phases. The fluorescent protein markers were used as Förster resonance energy transfer (FRET) pairs in intact cells. An increase of homologous FRET between L10 probes showed that depleting membrane cholesterol shrank L_o domains and enlarged L_d domains, whereas a decrease of L10 FRET showed that adding more cholesterol enlarged L_o and shrank L_d Heterologous FRET signals between the lipid domain probes and phosphoinositide marker proteins suggested that phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P ₂] and phosphatidylinositol 4-phosphate (PtdIns4P) are present in both L_o and L_d domains. In kinetic analysis, muscarinic-receptor-activated phospholipase C (PLC) depleted PtdIns(4,5)P ₂ and PtdIns4P more rapidly and produced diacylglycerol (DAG) more rapidly in L_o than in L_d Further, PtdIns(4,5)P ₂ was restored more rapidly in L_o than in L_d Thus destruction and restoration of PtdIns(4,5)P ₂ are faster in L_o than in L_d This suggests that L_o is enriched with both the receptor G protein/PLC pathway and the PtdIns/PI4-kinase/PtdIns4P pathway. The significant kinetic differences of lipid depletion and restoration also mean that exchange of lipids between these domains is much slower than free diffusion predicts.

Lipid-Modulating Agents for Prevention or Treatment of COVID-19 in Randomized Trials

Coronavirus disease 2019 (COVID-19) is associated with systemic inflammation, endothelial activation, and multi-organ manifestations. Lipid modulating agents may be useful in treating patients with COVID-19. They may inhibit viral entry by lipid raft disruption or ameliorate the inflammatory response and endothelial activation. In addition, dyslipidemia with lower high-density lipoprotein cholesterol and higher triglycerides portends worse outcome in patients with COVID-19. Upon a systematic search, 40 RCTs with lipid modulating agents were identified, including 17 statin trials, 14 omega-3 fatty acids RCTs, 3 fibrates RCTs, 5 niacin RCTs, and 1 dalcetrapib RCT for management or prevention of COVID-19. This manuscript summarizes the ongoing or completed randomized controlled trials (RCTs) of lipid modulating agents in COVID-19 and the implications of these trials for patient management.

COVID-19 enters the expanding network of apolipoprotein E4-related pathologies

COVID-19 incidence and case fatality rates (CFR) differ among ethnicities, stimulating efforts to pinpoint genetic factors that could explain these phenomena. In this regard, the multiallelic apolipoprotein E (APOE) gene has recently been interrogated in the UK biobank cohort, demonstrating associations of the APOE ε4/ε4 genotype with COVID-19 severity and mortality. The frequency of the ε4 allele and thus the distribution of APOE ε4/ε4 genotype may differ among populations. We have assessed APOE genotypes in 1638 Greek individuals, based on haplotypes derived from SNP rs7412 and rs429358 and found reduced frequency of ε4/ε4 compared to the British cohort. Herein we discuss this finding in relation to CFR and hypothesize on the potential mechanisms linking APOE ε4/ε4 to severe COVID-19. We postulate that the metabolic deregulation ensued by APOE4, manifested by elevated cholesterol and oxidized lipoprotein levels, may be central to heightened pneumocyte susceptibility to infection and to exaggerated lung inflammation associated with the ε4/ε4 genotype. We also discuss putative dietary and pharmacological approaches for the prevention and management of COVID-19 in APOE ε4/ε4 individuals.