Repurposing functional inhibitors of acid sphingomyelinase (fiasmas): an opportunity against SARS-CoV-2 infection?

Molecular docking as a tool for the discovery of novel insight about the role of acid sphingomyelinase inhibitors in SARS- CoV-2 infectivity

Recently, COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its variants, caused > 6 million deaths. Symptoms included respiratory strain and complications, leading to severe pneumonia. SARS-CoV-2 attaches to the ACE-2 receptor of the host cell membrane to enter. Targeting the SARS-CoV-2 entry may effectively inhibit infection. Acid sphingomyelinase (ASMase) is a lysosomal protein that catalyzes the conversion of sphingolipid (sphingomyelin) to ceramide. Ceramide molecules aggregate/assemble on the plasma membrane to form "platforms" that facilitate the viral intake into the cell. Impairing the ASMase activity will eventually disrupt viral entry into the cell. In this review, we identified the metabolism of sphingolipids, sphingolipids' role in cell signal transduction cascades, and viral infection mechanisms. Also, we outlined ASMase structure and underlying mechanisms inhibiting viral entry 40 with the aid of inhibitors of acid sphingomyelinase (FIASMAs). In silico molecular docking analyses of FIASMAs with inhibitors revealed that dilazep (S = - 12.58 kcal/mol), emetine (S = - 11.65 kcal/mol), pimozide (S = - 11.29 kcal/mol), carvedilol (S = - 11.28 kcal/mol), mebeverine (S = - 11.14 kcal/mol), cepharanthine (S = - 11.06 kcal/mol), hydroxyzin (S = - 10.96 kcal/mol), astemizole (S = - 10.81 kcal/mol), sertindole (S = - 10.55 kcal/mol), and bepridil (S = - 10.47 kcal/mol) have higher inhibition activity than the candidate drug amiodarone (S = - 10.43 kcal/mol), making them better options for inhibition.

In silico analysis of the antidepressant fluoxetine and similar drugs as inhibitors of the human protein acid sphingomyelinase: a related SARS-CoV-2 inhibition pathway

Acid Sphingomyelinase (ASM) is a human phosphodiesterase that catalyzes the metabolism of sphingomyelin (SM) to ceramide and phosphocholine. ASM is involved in the plasma membrane cell repair and is associated with the lysosomal inner lipid membrane by nonbonding interactions. The disruption of those interaction would result in ASM release into the lysosomal lumen and consequent degradation of its structure. Furthermore, SARS-CoV-2 infection has been linked with ASM activation and with a ceramide domain formation in the outer leaflet of the plasma membrane that is thought to be crucial for the viral particles recognition by the host cells. In this study, we have explored in silico the behavior of fluoxetine and related drugs as potential inhibitors of ASM. Theoretically, these drugs would be able to overpass lysosomal membrane and reach the interactions that sustain ASM structure, breaking them and inhibiting the ASM. The analyses of docking data indicated that fluoxetine allocated mainly in the N-terminal saposin domain via nonbonding interactions, mostly of hydrophobic nature. Similar results were obtained for venlafaxine, citalopram, atomoxetine, nisoxetine and fluoxetine's main metabolite norfluoxetine. In conclusion, it was observed that the saposin allocation may be a good indicative of the drugs inhibition mechanism, once this domain is responsible for the binding of ASM to lysosomal membrane and some of those drugs have previously been reported to inhibit the phosphodiesterase by releasing its structure in the lysosomal lumen. Our MD data also provides some insight about natural ligand C18 sphingomyelin conformations on saposin.Communicated by Ramaswamy H. Sarma.

Repurposing FIASMAs against Acid Sphingomyelinase for COVID-19: A Computational Molecular Docking and Dynamic Simulation Approach

Over the past few years, COVID-19 has caused widespread suffering worldwide. There is great research potential in this domain and it is also necessary. The main objective of this study was to identify potential inhibitors against acid sphingomyelinase (ASM) in order to prevent coronavirus infection. Experimental studies revealed that SARS-CoV-2 causes activation of the acid sphingomyelinase/ceramide pathway, which in turn facilitates the viral entry into the cells. The objective was to inhibit acid sphingomyelinase activity in order to prevent the cells from SARS-CoV-2 infection. Previous studies have reported functional inhibitors against ASM (FIASMAs). These inhibitors can be exploited to block the entry of SARS-CoV-2 into the cells. To achieve our objective, a drug library containing 257 functional inhibitors of ASM was constructed. Computational molecular docking was applied to dock the library against the target protein (PDB: 5I81). The potential binding site of the target protein was identified through structural alignment with the known binding pocket of a protein with a similar function. AutoDock Vina was used to carry out the docking steps. The docking results were analyzed and the inhibitors were screened based on their binding affinity scores and ADME properties. Among the 257 functional inhibitors, Dutasteride, Cepharanthine, and Zafirlukast presented the lowest binding affinity scores of −9.7, −9.6, and −9.5 kcal/mol, respectively. Furthermore, computational ADME analysis of these results revealed Cepharanthine and Zafirlukast to have non-toxic properties. To further validate these findings, the top two inhibitors in complex with the target protein were subjected to molecular dynamic simulations at 100 ns. The molecular interactions and stability of these compounds revealed that these inhibitors could be a promising tool for inhibiting SARS-CoV-2 infection.

Acid sphingomyelinase (ASM) and COVID-19: A review of the potential use of ASM inhibitors against SARS-CoV-2

In the last 2 years, different pharmacological agents have been indicated as potential inhibitors of SARS-CoV-2 in vitro. Specifically, drugs termed as functional inhibitors of acid sphingomyelinase (FIASMAs) have proved to inhibit the SARS-CoV-2 replication using different types of cells. Those therapeutic agents share several chemical structure characteristics and some well-known representatives are fluoxetine, escitalopram, fluvoxamine, and others. Most of the FIASMAs are primarily used as effective therapeutic agents to treat different pathologies, therefore, they are natural drug candidates for repositioning strategy. In this review, we summarize the two main proposed mechanisms mediating acid sphingomyelinase (ASM) inhibition and how they can explain the inhibition of SARS-CoV-2 replication by FIASMAs. The first mechanism implies a disruption in the lysosomal pH fall as the endosome-lysosome moves toward the interior of the cell. In fact, changes in cholesterol levels in endosome-lysosome membranes, which are associated with ASM inhibition is thought to be mediated by lysosomal proton pump (ATP-ase) inactivation. The second mechanism involves the formation of an extracellular ceramide-rich domain, which is blocked by FIASMAs. The ceramide-rich domains are believed to facilitate the SARS-CoV-2 entrance into the host cells.

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.

COVID-19 Outcomes: Does the Use of Psychotropic Drugs Make a Difference? Accumulating Evidence of a Beneficial Effect of Antidepressants-A Scoping Review

PURPOSE/BACKGROUND

Studies for repurposed drugs in severe acute respiratory syndrome coronavirus type 2-infected and coronavirus disease 2019 (COVID-19) patients are ongoing. According to preclinical research, antidepressants (ADs) might be useful in the treatment of COVID-19.

METHODS/PROCEDURES

We conducted a scoping review including clinical studies on AD effects on SARS-CoV-2 infection and COVID-19.

FINDING/RESULTS

As of January 2, 2022, we found 14 clinical studies, which could be included into this review. Among them, there were 2 randomized, placebo-controlled studies and 2 prospective parallel-group studies about the efficacy/effectiveness and tolerability of fluvoxamine. The remaining studies were mainly retrospective studies considering COVID-19 hospital populations predominantly exposed to fluoxetine (N = 3), other selective serotonin reuptake inhibitors (SSRI), selective norepinephrine reuptake inhibitors (SNRI), and trazodone. The vast majority were hospital studies and assessed COVID-19 severity (morbidity) and mortality as primary endpoints. The only outpatient study (fluvoxamine) investigated the COVID-19-related hospitalization rate, and 1 psychiatric hospital study (SSRI, SNRI, trazodone) focused on the SARS-CoV-2 infection rate.

IMPLICATIONS/CONCLUSIONS

At present, the best evidence of an "anti-COVID-19" potential of ADs exists for fluvoxamine and, to a lesser extent, for fluoxetine. Preliminary evidence had found that patients exposed to SSRI or SNRI substance classes might have a reduced mortality risk and that trazodone might reduce SARS-CoV-2 infection rates. Three studies found no relevant influence of ADs on COVID-19 morbidity and mortality, and 1 study described increased mortality. The latter study, however, did not differentiate between psychotropic medication and ADs. Tricyclics and monoamine oxidase inhibitors are still absolute "dark zones" in COVID-19 research. Further controlled studies testing the effectiveness/efficacy and tolerability/safety (as well as the treatment timing and duration) of different AD substance classes in COVID-19 and post/long-COVID patients of various populations are warranted.

A critical analysis of SARS-CoV-2 (COVID-19) complexities, emerging variants, and therapeutic interventions and vaccination strategies

Coronavirus is a family of viruses that can cause diseases such as the common cold, severe acute respiratory syndrome (SARS), and Middle East respiratory syndrome (MERS). The universal outbreak of coronavirus disease 2019 (COVID-19) caused by SARS coronaviruses 2 (SARS-CoV-2) has become a global pandemic. The β-Coronaviruses, which caused SARS-CoV-2 (COVID-19), have spread in more than 213 countries, infected over 81 million people, and caused more than 1.79 million deaths. COVID-19 symptoms vary from mild fever, flu to severe pneumonia in severely ill patients. Difficult breathing, acute respiratory distress syndrome (ARDS), acute kidney disease, liver damage, and multi-organ failure ultimately lead to death. Researchers are working on different pre-clinical and clinical trials to prevent this deadly pandemic by developing new vaccines. Along with vaccines, therapeutic intervention is an integral part of healthcare response to address the ongoing threat posed by COVID-19. Despite the global efforts to understand and fight against COVID-19, many challenges need to be addressed. This article summarizes the current pandemic, different strains of SARS-CoV-2, etiology, complexities, surviving medications of COVID-19, and so far, vaccination for the treatment of COVID-19.

Low-Dose Fluvoxamine Modulates Endocytic Trafficking of SARS-CoV-2 Spike Protein: A Potential Mechanism for Anti-COVID-19 Protection by Antidepressants

Commonly prescribed antidepressants may be associated with protection against severe COVID-19. The mechanism of their action in this context, however, remains unknown. Here, I investigated the effect of an antidepressant drug fluvoxamine on membrane trafficking of the SARS-CoV-2 spike protein and its cell host receptor ACE2 in HEK293T cells. A sub-therapeutic concentration (80 nM) of fluvoxamine rapidly upregulated fluid-phase endocytosis, resulting in enhanced accumulation of the spike-ACE2 complex in enlarged early endosomes. Diversion of endosomal trafficking provides a simple cell biological mechanism consistent with the protective effect of antidepressants against COVID-19, highlighting their therapeutic and prophylactic potential.

Strategies for drug repurposing against coronavirus targets

Repurposing regulatory agency approved drugs and investigational compounds with known safety profiles can significantly fast track the drug development timeline over de novo drug discovery, with lower investment requirements and improved attrition rate. These advantages are vital in any epidemic or pandemic situation, where hospital beds are occupied by patients for whom there is no known treatment. Here we examine drug repurposing in the context of human coronaviruses, SARS-CoV, MERS-CoV, and, in particular, SARS-CoV-2, the virus currently causing a continued widespread pandemic with substantial impacts on public health and economy. The key druggable targets explored were those involved in viral entry, viral replication, and viral-induced ARDS, as well as viral proteases, with a focus on the strategy by which the drugs were repurposed.

Ceramide Metabolism Enzymes-Therapeutic Targets against Cancer

Sphingolipids are both structural molecules that are essential for cell architecture and second messengers that are involved in numerous cell functions. Ceramide is the central hub of sphingolipid metabolism. In addition to being the precursor of complex sphingolipids, ceramides induce cell cycle arrest and promote cell death and inflammation. At least some of the enzymes involved in the regulation of sphingolipid metabolism are altered in carcinogenesis, and some are targets for anticancer drugs. A number of scientific reports have shown how alterations in sphingolipid pools can affect cell proliferation, survival and migration. Determination of sphingolipid levels and the regulation of the enzymes that are implicated in their metabolism is a key factor for developing novel therapeutic strategies or improving conventional therapies. The present review highlights the importance of bioactive sphingolipids and their regulatory enzymes as targets for therapeutic interventions with especial emphasis in carcinogenesis and cancer dissemination.

Update on Functional Inhibitors of Acid Sphingomyelinase (FIASMAs) in SARS-CoV-2 Infection

The SARS-CoV-2 outbreak is characterized by the need of the search for curative drugs for treatment. In this paper, we present an update of knowledge about the interest of the functional inhibitors of acid sphingomyelinase (FIASMAs) in SARS-CoV-2 infection. Forty-nine FIASMAs have been suggested in the treatment of SARS-CoV-2 infection using in silico, in vitro or in vivo studies. Further studies using large-sized, randomized and double-blinded controlled clinical trials are needed to evaluate FIASMAs in SARS-CoV-2 infection as off-label therapy.

Ceramide and Related Molecules in Viral Infections

Ceramide is a lipid messenger at the heart of sphingolipid metabolism. In concert with its metabolizing enzymes, particularly sphingomyelinases, it has key roles in regulating the physical properties of biological membranes, including the formation of membrane microdomains. Thus, ceramide and its related molecules have been attributed significant roles in nearly all steps of the viral life cycle: they may serve directly as receptors or co-receptors for viral entry, form microdomains that cluster entry receptors and/or enable them to adopt the required conformation or regulate their cell surface expression. Sphingolipids can regulate all forms of viral uptake, often through sphingomyelinase activation, and mediate endosomal escape and intracellular trafficking. Ceramide can be key for the formation of viral replication sites. Sphingomyelinases often mediate the release of new virions from infected cells. Moreover, sphingolipids can contribute to viral-induced apoptosis and morbidity in viral diseases, as well as virus immune evasion. Alpha-galactosylceramide, in particular, also plays a significant role in immune modulation in response to viral infections. This review will discuss the roles of ceramide and its related molecules in the different steps of the viral life cycle. We will also discuss how novel strategies could exploit these for therapeutic benefit.

Psychopathological Impact and Resilient Scenarios in Inpatient with Schizophrenia Spectrum Disorders Related to Covid Physical Distancing Policies: A Systematic Review

The COVID-19 epidemic posed great challenges to the healthcare community. To contain the epidemiological emergency, confinement measures were instituted, affecting the entire population. The lack of social contact, as well as the disruption of daily life, caused the exacerbation of anxiety and depressive symptoms. The present review of the literature aims to investigate what the effects of the pandemic have been on patients with schizophrenia, hypothesizing, an exacerbation of psychotic symptomatology (positive, negative, disorganized symptoms). Between November 2020 and January 2021, 5353 articles were collected and analyzed from the databases of the ResearchGate, Pubmed, and Psycnet websites, subjected to PRISMA methodology. Of these, 11 were evaluated for eligibility, but only three were included in the study because they met all inclusion criteria. The research did not confirm the expected results, showing that any kind of worsening of schizophrenic symptomatology involved the study samples. However, interesting outcomes were highlighted, such as a significant increase in general well-being during the early period of the pandemic, especially by women, or an increase in CPR (C-reactive Protein) levels in the blood, signaling an inflammatory state. Although the systematic review refuted the initial hypothesis, this must be a starting point: the topic is recent and these findings leave ample room for further investigation, particularly in long-term longitudinal research. It is possible that the true response to this disruption of daily life that occurred only during the past year may manifest itself later in time. On the other hand, interesting outcomes have been brought to light that may provide further interesting research insights.

Association between Functional Inhibitors of Acid Sphingomyelinase (FIASMAs) and Reduced Risk of Death in COVID-19 Patients: A Retrospective Cohort Study

Given the current scarcity of curative treatment of COVID-19, the search for an effective treatment modality among all available medications has become a priority. This study aimed at investigating the role of functional inhibitors of acid sphingomyelinase (FIASMAs) on in-hospital COVID-19 mortality. In this retrospective cohort study, we included adult in-patients with laboratory-confirmed COVID-19 between 1 March 2020 and 31 August 2020 with definite outcomes (discharged hospital or deceased) from Erasme Hospital (Brussels, Belgium). We used univariate and multivariate logistic regression models to explore the risk factors associated with in-hospital mortality. We included 350 patients (205 males, 145 females) with a mean age of 63.24 years (SD = 17.4, range: 21-96 years). Seventy-two patients died in the hospital and 278 were discharged. The four most common comorbidities were hypertension (184, 52.6%), chronic cardiac disease (110, 31.4%), obesity (96, 27.8%) and diabetes (95, 27.1%). Ninety-three participants (26.6%) received a long-term prescription for FIASMAs. Among these, 60 (64.5%) received amlodipine. For FIASMAs status, multivariable regression showed increasing odds ratio (OR) for in-hospital deaths associated with older age (OR 1.05, 95% CI: 1.02-1.07; p = 0.00015), and higher prevalence of malignant neoplasm (OR 2.09, 95% CI: 1.03-4.22; p = 0.039). Nonsignificant decreasing OR (0.53, 95% CI: 0.27-1.04; p = 0.064) was reported for FIASMA status. For amlodipine status, multivariable regression revealed increasing OR of in-hospital deaths associated with older age (OR 1.04, 95% CI: 1.02-1.07; p = 0.0009), higher prevalence of hypertension (OR 2.78, 95% CI: 1.33-5.79; p = 0.0062) and higher prevalence of malignant neoplasm (OR 2.71, 95% CI: 1.23-5.97; p = 0.013), then secondarily decreasing OR of in-hospital death associated with long-term treatment with amlodipine (OR 0.24, 95% CI: 0.09-0.62; p = 0.0031). Chronic treatment with amlodipine could be significantly associated with low mortality of COVID-19 in-patients.