NFKB2 haploinsufficiency identified via screening for IFN-α2 autoantibodies in children and adolescents hospitalized with SARS-CoV-2-related complications.

BACKGROUND: Autoantibodies against type I IFNs occur in approximately 10% of adults with life-threatening coronavirus disease 2019 (COVID-19). The frequency of anti-IFN autoantibodies in children with severe sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is unknown. OBJECTIVE: We quantified anti-type I IFN autoantibodies in a multicenter cohort of children with severe COVID-19, multisystem inflammatory syndrome in children (MIS-C), and mild SARS-CoV-2 infections. METHODS: Circulating anti-IFN-α2 antibodies were measured by a radioligand binding assay. Whole-exome sequencing, RNA sequencing, and functional studies of peripheral blood mononuclear cells were used to study any patients with levels of anti-IFN-α2 autoantibodies exceeding the assay's positive control. RESULTS: Among 168 patients with severe COVID-19, 199 with MIS-C, and 45 with mild SARS-CoV-2 infections, only 1 had high levels of anti-IFN-α2 antibodies. Anti-IFN-α2 autoantibodies were not detected in patients treated with intravenous immunoglobulin before sample collection. Whole-exome sequencing identified a missense variant in the ankyrin domain of NFKB2, encoding the p100 subunit of nuclear factor kappa-light-chain enhancer of activated B cells, aka NF-κB, essential for noncanonical NF-κB signaling. The patient's peripheral blood mononuclear cells exhibited impaired cleavage of p100 characteristic of NFKB2 haploinsufficiency, an inborn error of immunity with a high prevalence of autoimmunity. CONCLUSIONS: High levels of anti-IFN-α2 autoantibodies in children and adolescents with MIS-C, severe COVID-19, and mild SARS-CoV-2 infections are rare but can occur in patients with inborn errors of immunity.

SARS-CoV-2 Variants Show Different Host Cell Proteome Profiles With Delayed Immune Response Activation in Omicron-Infected Cells.

The ancestral SARS-CoV-2 strain that initiated the Covid-19 pandemic at the end of 2019 has rapidly mutated into multiple variants of concern with variable pathogenicity and increasing immune escape strategies. However, differences in host cellular antiviral responses upon infection with SARS-CoV-2 variants remain elusive. Leveraging whole-cell proteomics, we determined host signaling pathways that are differentially modulated upon infection with the clinical isolates of the ancestral SARS-CoV-2 B.1 and the variants of concern Delta and Omicron BA.1. Our findings illustrate alterations in the global host proteome landscape upon infection with SARS-CoV-2 variants and the resulting host immune responses. Additionally, viral proteome kinetics reveal declining levels of viral protein expression during Omicron BA.1 infection when compared to ancestral B.1 and Delta variants, consistent with its reduced replication rates. Moreover, molecular assays reveal deferral activation of specific host antiviral signaling upon Omicron BA.1 and BA.2 infections. Our study provides an overview of host proteome profile of multiple SARS-CoV-2 variants and brings forth a better understanding of the instigation of key immune signaling pathways causative for the differential pathogenicity of SARS-CoV-2 variants.

Enhanced Expression of RAGE AXIS Is Associated with Severity of COVID-19 in Patients with Comorbidities.

Background: There is a limited understanding of molecular and cellular events that derive disease progression in patients with corona virus disease 2019 (COVID-19). Receptor for advanced glycation end products (RAGE) is hyperactive in development and complications of several diseases by mediating oxidative stress and inflammation in the body. The present study aims to explore activation of RAGE signaling in patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with preexisting comorbidities, including hypertension and or diabetes. Methods: A total of 442 subjects with COVID-19, were recruited for the study. The molecular mechanism of Covid-19 was explored in blood cells, using ELISA, RT- PCR and Western blot. Results: Enhanced levels of ligands of RAGE, including AGEs, S100, and high-mobility group box-1 (HMGB-1) were observed in COVID-19 patients with severe diseases; however, their level was significantly higher in COVID-19 patients with comorbidities compared to COVID-19 patients without comorbidities. The expression of RAGE in parallel to ligands accumulation was significantly increased in patients with severe disease and comorbidities compared to COVID-19 patients with severe disease without comorbidities. The expression of downstream effectors of RAGE, including STAT-3 and nuclear factor kappa B (NF-kB), was also enhanced and their activity was increased in COVID-19 patients with comorbidities. Levels of inflammatory and oxidative stress biomarkers were markedly increased in COVID-19 patients with comorbidities. Conclusions: We conclude that upregulated RAGE axis plays critical role, to worsen the severity of the SARS-CoV-2 infection in patients with preexisting comorbidities and partly explain inflammatory and oxidative stress storm in severe COVID-19 patients.

In vitro and in silico perspectives to explain anticancer activity of a novel syringic acid analog ((4-(1H-1, 3-benzodiazol-2-yl)-2, 6-dimethoxy phenol)) through apoptosis activation and NFkB inhibition in K562 leukemia cells.

Syringic acid (SA) is an active carcinogenesis inhibitor; however, the low bioavailability and unstable functional groups hinder its activity. Here, a chemically synthesized novel SA analog (SA10) is evaluated for its anticancer activity using in-vitro and in-silico studies. K562 cell line study revealed that SA10 had shown a higher rate of inhibition (IC50 = 50.40 µg/mL) than its parental compound, SA (IC50 = 96.92 µg/mL), at 50 µM concentration. The inhibition ratio was also been evaluated by checking the expression level of NFkB and Bcl-2 and showing that SA10 has two-fold increase in the inhibitory mechanism than SA. This result demonstrates that SA10 acts as an NFkB inhibitor and an apoptosis inducer. Further, molecular docking and simulation have been performed to get insights into the possible inhibitory mechanism of SA and SA10 on NFkB at the atomistic level. The molecular docking results exemplify that both SA and SA10 bind to the active site of NFkB, thereby interfering with the association between DNA and NFkB. SA10 exhibits a more robust binding affinity than SA and is firmly docked well into the interior of the NFkB, as confirmed by MM-PBSA calculations. In a nutshell, the Benzimidazole scaffold containing SA10 has shown more NFkB inhibitory activity in K562 cells than SA, which could be helpful as an ideal therapeutic NFkB inhibitor for treating cancers.

Cell cycle block by p53 activation reduces SARS-CoV-2 release in infected alveolar basal epithelial A549-hACE2 cells.

SARS-CoV viruses have been shown to downregulate cellular events that control antiviral defenses. They adopt several strategies to silence p53, key molecule for cell homeostasis and immune control, indicating that p53 has a central role in controlling their proliferation in the host. Specific actions are the stabilization of its inhibitor, MDM2, and the interference with its transcriptional activity. The aim of our work was to evaluate a new approach against SARS-CoV-2 by using MDM2 inhibitors to raise p53 levels and activate p53-dependent pathways, therefore leading to cell cycle inhibition. Experimental setting was performed in the alveolar basal epithelial cell line A549-hACE2, expressing high level of ACE2 receptor, to allow virus entry, as well as p53 wild-type. Cells were treated with several concentrations of Nutlin-3 or RG-7112, two known MDM2 inhibitors, for the instauration of a cell cycle block steady-state condition before and during SARS-CoV-2 infection, and for the evaluation of p53 activation and impact on virus release and related innate immune events. The results indicated an efficient cell cycle block with inhibition of the virion release and a significant inhibition of IL-6, NF-kB and IFN-λ expression. These data suggest that p53 is an efficient target for new therapies against the virus and that MDM2 inhibitors deserve to be further investigated in this field.

SARS-CoV-2-Induced Immunosuppression: A Molecular Mimicry Syndrome.

Background Contrary to immunological expectations, decay of adaptive responses against severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) characterizes recovered patients compared with patients who had a severe disease course or died following SARS-CoV-2 infection. This raises the question of the causes of the virus-induced immune immunosuppression. Searching for molecular link(s) between SARS-CoV-2 immunization and the decay of the adaptive immune responses, SARS-CoV-2 proteome was analyzed for molecular mimicry with human proteins related to immunodeficiency. The aim was to verify the possibility of cross-reactions capable of destroying the adaptive immune response triggered by SARS-CoV-2. Materials and Methods Human immunodeficiency-related proteins were collected from UniProt database and analyzed for sharing of minimal immune determinants with the SARS-CoV-2 proteome. Results Molecular mimicry and consequent potential cross-reactivity exist between SARS-CoV-2 proteome and human immunoregulatory proteins such as nuclear factor kappa B (NFKB), and variable diversity joining V(D)J recombination-activating gene (RAG). Conclusion The data (1) support molecular mimicry and the associated potential cross-reactivity as a mechanism that can underlie self-reactivity against proteins involved in B- and T-cells activation/development, and (2) suggest that the extent of the immunosuppression is dictated by the extent of the immune responses themselves. The higher the titer of the immune responses triggered by SARS-CoV-2 immunization, the more severe can be the cross-reactions against the human immunodeficiency-related proteins, the more severe the immunosuppression. Hence, SARS-CoV-2-induced immunosuppression can be defined as a molecular mimicry syndrome. Clinically, the data imply that booster doses of SARS-CoV-2 vaccines may have opposite results to those expected.

Conjunctival epithelial cells resist productive SARS-CoV-2 infection.

Conjunctival epithelial cells, which express viral-entry receptors angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine type 2 (TMPRSS2), constitute the largest exposed epithelium of the ocular surface tissue and may represent a relevant viral-entry route. To address this question, we generated an organotypic air-liquid-interface model of conjunctival epithelium, composed of basal, suprabasal, and superficial epithelial cells, and fibroblasts, which could be maintained successfully up to day 75 of differentiation. Using single-cell RNA sequencing (RNA-seq), with complementary imaging and virological assays, we observed that while all conjunctival cell types were permissive to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome expression, a productive infection did not ensue. The early innate immune response to SARS-CoV-2 infection in conjunctival cells was characterised by a robust autocrine and paracrine NF-κB activity, without activation of antiviral interferon signalling. Collectively, these data enrich our understanding of SARS-CoV-2 infection at the human ocular surface, with potential implications for the design of preventive strategies and conjunctival transplantation.

p53/NF-kB Balance in SARS-CoV-2 Infection: From OMICs, Genomics and Pharmacogenomics Insights to Tailored Therapeutic Perspectives (COVIDomics).

SARS-CoV-2 infection affects different organs and tissues, including the upper and lower airways, the lung, the gut, the olfactory system and the eye, which may represent one of the gates to the central nervous system. Key transcriptional factors, such as p53 and NF-kB and their reciprocal balance, are altered upon SARS-CoV-2 infection, as well as other key molecules such as the virus host cell entry mediator ACE2, member of the RAS-pathway. These changes are thought to play a central role in the impaired immune response, as well as in the massive cytokine release, the so-called cytokine storm that represents a hallmark of the most severe form of SARS-CoV-2 infection. Host genetics susceptibility is an additional key side to consider in a complex disease as COVID-19 characterized by such a wide range of clinical phenotypes. In this review, we underline some molecular mechanisms by which SARS-CoV-2 modulates p53 and NF-kB expression and activity in order to maximize viral replication into the host cells. We also face the RAS-pathway unbalance triggered by virus-ACE2 interaction to discuss potential pharmacological and pharmacogenomics approaches aimed at restoring p53/NF-kB and ACE1/ACE2 balance to counteract the most severe forms of SARS-CoV-2 infection.

The status and analysis of common mutations found in the SARS-CoV-2 whole genome sequences from Bangladesh.

Rapid emergence of covid-19 variants by continuous mutation made the world experience continuous waves of infections and as a result, a huge number of death-toll recorded so far. It is, therefore, very important to investigate the diversity and nature of the mutations in the SARS-CoV-2 genomes. In this study, the common mutations occurred in the whole genome sequences of SARS-CoV-2 variants of Bangladesh in a certain timeline were analyzed to better understand its status. Hence, a total of 78 complete genome sequences available in the NCBI database were obtained, aligned and further analyzed. Scattered Single Nucleotide Polymorphisms (SNPs) were identified throughout the genome of variants and common SNPs such as: 241:C>T in the 5'UTR of Open Reading Frame 1A (ORF1A), 3037: C>T in Non-structural Protein 3 (NSP3), 14,408: C>T in ORF6 and 23,402: A>G, 23,403: A>G in Spike Protein (S) were observed, but all of them were synonymous mutations. About 97% of the studied genomes showed a block of tri-nucleotide alteration (GGG>AAC), the most common non-synonymous mutation in the 28,881-28,883 location of the genome. This block results in two amino acid changes (203-204: RG>KR) in the SR rich motif of the nucleocapsid (N) protein of SARS-CoV-2, introducing a lysine in between serine and arginine. The N protein structure of the mutant was predicted through protein modeling. However, no observable difference was found between the mutant and the reference (Wuhan) protein. Further, the protein stability changes upon mutations were analyzed using the I-Mutant2.0 tool. The alteration of the arginine to lysine at the amino acid position 203, showed reduction of entropy, suggesting a possible impact on the overall stability of the N protein. The estimation of the non-synonymous to synonymous substitution ratio (dN/dS) were analyzed for the common mutations and the results showed that the overall mean distance among the N-protein variants were statistically significant, supporting the non-synonymous nature of the mutations. The phylogenetic analysis of the selected 78 genomes, compared with the most common genomic variants of this virus across the globe showed a distinct cluster for the analyzed Bangladeshi sequences. Further studies are warranted for conferring any plausible association of these mutations with the clinical manifestation.

Alu RNA Structural Features Modulate Immune Cell Activation and A-to-I Editing of Alu RNAs Is Diminished in Human Inflammatory Bowel Disease.

Alu retrotransposons belong to the class of short interspersed nuclear elements (SINEs). Alu RNA is abundant in cells and its repetitive structure forms double-stranded RNAs (dsRNA) that activate dsRNA sensors and trigger innate immune responses with significant pathological consequences. Mechanisms to prevent innate immune activation include deamination of adenosines to inosines in dsRNAs, referred to as A-to-I editing, degradation of Alu RNAs by endoribonucleases, and sequestration of Alu RNAs by RNA binding proteins. We have previously demonstrated that widespread loss of Alu RNA A-to-I editing is associated with diverse human diseases including viral (COVID-19, influenza) and autoimmune diseases (multiple sclerosis). Here we demonstrate loss of A-to-I editing in leukocytes is also associated with inflammatory bowel diseases. Our structure-function analysis demonstrates that ability to activate innate immune responses resides in the left arm of Alu RNA, requires a 5'-PPP, RIG-I is the major Alu dsRNA sensor, and A-to-I editing disrupts both structure and function. Further, edited Alu RNAs inhibit activity of unedited Alu RNAs. Altering Alu RNA nucleotide sequence increases biological activity. Two classes of Alu RNAs exist, one class stimulates both IRF and NF-kB transcriptional activity and a second class only stimulates IRF transcriptional activity. Thus, Alu RNAs play important roles in human disease but may also have therapeutic potential.

SARS-CoV-2 Switches 'on' MAPK and NFκB Signaling via the Reduction of Nuclear DUSP1 and DUSP5 Expression.

Mitogen-activated protein kinases (MAPK) and NF-kappaB (NF-κB) pathway regulate many cellular processes and are essential for immune cells function. Their activity is controlled by dual-specificity phosphatases (DUSPs). A comprehensive analysis of publicly available gene expression data sets of human airway epithelial cells (AECs) infected with SARS-CoV-2 identified DUSP1 and DUSP5 among the lowest induced transcripts within these pathways. These proteins are known to downregulate MAPK and NF-κB pathways; and their lower expression was associated with increased activity of MAPK and NF-κB signaling and enhanced expression of proinflammatory cytokines such as TNF-α. Infection with other coronaviruses did not have a similar effect on these genes. Interestingly, treatment with chloroquine and/or non-steroidal anti-inflammatory drugs counteracted the SARS-CoV-2 induced reduction of DUSP1 and DUSP5 genes expression. Therapeutically, impeding this evasion mechanism of SARS-CoV-2 may help control the exaggerated activation of these immune regulatory pathways during a COVID-19 infection.

MicroRNAs based regulation of cytokine regulating immune expressed genes and their transcription factors in COVID-19.

BACKGROUND: Coronavirus disease 2019 is characterized by the elevation of a broad spectrum of inflammatory mediators associated with poor disease outcomes. We aimed at an in-silico analysis of regulatory microRNA and their transcription factors (TF) for these inflammatory genes that may help to devise potential therapeutic strategies in the future. METHODS: The cytokine regulating immune-expressed genes (CRIEG) were sorted from literature and the GEO microarray dataset. Their co-differentially expressed miRNA and transcription factors were predicted from publicly available databases. Enrichment analysis was done through mienturnet, MiEAA, Gene Ontology, and pathways predicted by KEGG and Reactome pathways. Finally, the functional and regulatory features were analyzed and visualized through Cytoscape. RESULTS: Sixteen CRIEG were observed to have a significant protein-protein interaction network. The ontological analysis revealed significantly enriched pathways for biological processes, molecular functions, and cellular components. The search performed in the miRNA database yielded ten miRNAs that are significantly involved in regulating these genes and their transcription factors. CONCLUSION: An in-silico representation of a network involving miRNAs, CRIEGs, and TF, which take part in the inflammatory response in COVID-19, has been elucidated. Thus, these regulatory factors may have potentially critical roles in the inflammatory response in COVID-19 and may be explored further to develop targeted therapeutic strategies and mechanistic validation.

Prediction and analysis of microRNAs involved in COVID-19 inflammatory processes associated with the NF-kB and JAK/STAT signaling pathways.

COVID-19 is the cause of a pandemic associated with substantial morbidity and mortality. As yet, there is no available approved drug to eradicate the virus. In this review article, we present an alternative study area that may contribute to the development of therapeutic targets for COVID-19. Growing evidence is revealing further pathophysiological mechanisms of COVID-19 related to the disregulation of inflammation pathways that seem to play a critical role toward COVID-19 complications. The NF-kB and JAK/STAT signaling pathways are highly activated in acute inflammation, and the excessive activity of these pathways in COVID-19 patients likely exacerbates the inflammatory responses of the host. A group of non-coding RNAs (miRNAs) manage certain features of the inflammatory process. In this study, we discuss recent advances in our understanding of miRNAs and their connection to inflammatory responses. Additionally, we consider the link between perturbations in miRNA levels and the onset of COVID-19 disease. Furthermore, previous studies published in the online databases, namely web of science, MEDLINE (PubMed), and Scopus, were reviewed for the potential role of miRNAs in the inflammatory manifestations of COVID-19. Moreover, we disclosed the interactions of inflammatory genes using STRING DB and designed interactions between miRNAs and target genes using Cityscape software. Several miRNAs, particularly miR-9, miR-98, miR-223, and miR-214, play crucial roles in the regulation of NF-kB and JAK-STAT signaling pathways as inflammatory regulators. Therefore, this group of miRNAs that mitigate inflammatory pathways can be further regarded as potential targets for far-reaching-therapeutic strategies in COVID-19 diseases.

Endoplasmic reticulum stress and NF-kB activation in SARS-CoV-2 infected cells and their response to antiviral therapy.

Unfolded protein response (UPR) and endoplasmic reticulum (ER) stress are aspects of SARS-CoV-2-host cell interaction with proposed role in the cytopathic and inflammatory pathogenesis of this viral infection. The role of the NF-kB pathway in these cellular processes remains poorly characterized. When investigated in VERO-E6 cells, SARS-CoV-2 infection was found to markedly stimulate NF-kB protein expression and activity. NF-kB activation occurs early in the infection process (6 hpi) and it is associated with increased MAPK signaling and expression of the UPR inducer IRE-1α. These signal transduction processes characterize the cellular stress response to the virus promoting a pro-inflammatory environment and caspase activation in the host cell. Inhibition of viral replication by the viral protease inhibitor Nelfinavir reverts all these molecular changes also stimulating c-Jun expression, a key component of the JNK/AP-1 pathway with important role in the IRE-1α-mediated transcriptional regulation of stress response genes with anti-inflammatory and cytoprotection function. The present study demonstrates that UPR signaling and its interaction with cellular MAPKs and the NF-kB activity are important aspects of SARS-CoV-2-host cell interaction that deserve further investigation to identify more efficient therapies for this viral infection.

NSAIDs/nitazoxanide/azithromycin repurposed for COVID-19: potential mitigation of the cytokine storm interleukin-6 amplifier via immunomodulatory effects.

INTRODUCTION: Mediators of immunity and inflammation are playing a crucial role in COVID-19 pathogenesis and complications as demonstrated by several genetic and clinical studies. Thus, repurposing of drugs that possess anti-inflammatory and/or immune-modulatory effects for COVID-19 is considered a rational approach. AREAS COVERED: We analyze selected studies that correlated COVID-19 with dysregulated interferon and inflammatory responses while reflecting on our academic and real-life experience using non-steroidal anti-inflammatory drugs, nitazoxanide and azithromycin for management of COVID-19. Moreover, we interpret the results that suggested a potential survival benefit of low-dose aspirin and colchicine when used for COVID-19. EXPERT OPINION: Nitazoxanide/azithromycin combination has been first hypothesized by the author and practiced by him and several researchers to benefit COVID-19 patients due to a potential ability to augment the natural interferon response as well as their positive immunomodulatory effects on several cytokines. Furthermore, NSAIDs, that are unfortunately currently at best of second choice after paracetamol, have been early postulated and clinically practiced by the author to prevent or ameliorate COVID-19 complications and mortality due to their anti-inflammatory and immunomodulatory properties. Finally, we repeat our previous call to adopt our observational study that used these drugs in sufficiently powered double blind randomized clinical trials.

Immunogenicity of Pfizer-BioNTech COVID-19 vaccine in patients with inborn errors of immunity.

BACKGROUND: In mid-December 2020, Israel started a nationwide mass vaccination campaign against coronavirus disease 2019 (COVID-19). In the first few weeks, medical personnel, elderly citizens, and patients with chronic diseases were prioritized. As such, patients with primary and secondary immunodeficiencies were encouraged to receive the vaccine. Although the efficacy of RNA-based COVID-19 vaccines has been demonstrated in the general population, little is known about their efficacy and safety in patients with inborn errors of immunity (IEI). OBJECTIVE: Our aim was to evaluate the humoral and cellular immune response to COVID-19 vaccine in a cohort of patients with IEI. METHODS: A total of 26 adult patients were enrolled, and plasma and peripheral blood mononuclear cells were collected from them 2 weeks following the second dose of Pfizer-BioNTech COVID-19 vaccine. Humoral response was evaluated by testing anti-SARS-CoV-2 spike (S) receptor-binding domain and antinucleocapsid antibody titers and evaluating neutralizing ability by inhibition of receptor-binding domain-angiotensin-converting enzyme 2 binding. Cellular immune response was evaluated by using ELISpot, estimating IL-2 and IFN-γ secretion in response to pooled SARS-CoV-2 S- or M-peptides. RESULTS: Our cohort included 18 patients with a predominantly antibody deficiency, 2 with combined immunodeficiency, 3 with immune dysregulation, and 3 with other genetically defined diagnoses. Twenty-two of them were receiving immunoglobulin replacement therapy. Of the 26 patients, 18 developed specific antibody response, and 19 showed S-peptide-specific T-cell response. None of the patients reported significant adverse events. CONCLUSION: Vaccinating patients with IEI is safe, and most patients were able to develop vaccine-specific antibody response, S-protein-specific cellular response, or both.

NF-κB signalling as a pharmacological target in COVID-19: potential roles for IKKß inhibitors.

Coronavirus disease 2019 (COVID-19) has been characterized by lymphopenia as well as a proinflammatory cytokine storm, which are responsible for the poor prognosis and multiorgan defects. The transcription factor nuclear factor-κB (NF-κB) modulates the functions of the immune cells and alters the gene expression profile of different cytokines in response to various pathogenic stimuli, while many proinflammatory factors have been known to induce NF-κB signalling cascade. Besides, NF-κB has been known to potentiate the production of reactive oxygen species (ROS) leading to apoptosis in various tissues in many diseases and viral infections. Though the reports on the involvement of the NF-κB signalling pathway in COVID-19 are limited, the therapeutic benefits of NF-κB inhibitors including dexamethasone, a synthetic form of glucocorticoid, have increasingly been realized. Considering the fact, the abnormal activation of the NF-κB resulting from severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection might be associated with the pathogenic profile of immune cells, cytokine storm and multiorgan defects. Thus, the pharmacological inactivation of the NF-κB signalling pathway can strongly represent a potential therapeutic target to treat the symptomatology of COVID-19. This article signifies pharmacological blockade of the phosphorylation of inhibitor of nuclear factor kappa B kinase subunit beta (IKKß), a key downstream effector of NF-κB signalling, for a therapeutic consideration to attenuate COVID-19.

Discovery of a AHR pelargonidin agonist that counter-regulates Ace2 expression and attenuates ACE2-SARS-CoV-2 interaction.

The severe acute respiratory syndrome (SARS)-CoV-2 is the pathogenetic agent of Corona Virus Induced Disease (COVID)19. The virus enters the human cells after binding to the angiotensin converting enzyme (ACE)2 receptor in target tissues. ACE2 expression is induced in response to inflammation. The colon expression of ACE2 is upregulated in patients with inflammatory bowel disease (IBD), highlighting a potential risk of intestinal inflammation in promoting viral entry in the human body. Because mechanisms that regulate ACE2 expression in the intestine are poorly understood and there is a need of anti-SARS-CoV-2 therapies, we have settled to investigate whether natural flavonoids might regulate the expression of Ace2 in intestinal models of inflammation. The results of these studies demonstrated that pelargonidin activates the Aryl hydrocarbon Receptor (AHR) in vitro and reverses intestinal inflammation caused by chronic exposure to high fat diet or to the intestinal braking-barrier agent TNBS in a AhR-dependent manner. In these two models, development of colon inflammation associated with upregulation of Ace2 mRNA expression. Colon levels of Ace2 mRNA were directly correlated with Tnf-α mRNA levels. Molecular docking studies suggested that pelargonidin binds a fatty acid binding pocket on the receptor binding domain of SARS-CoV-2 Spike protein. In vitro studies demonstrated that pelargonidin significantly reduces the binding of SARS-CoV-2 Spike protein to ACE2 and reduces the SARS-CoV-2 replication in a concentration-dependent manner. In summary, we have provided evidence that a natural flavonoid might hold potential in reducing intestinal inflammation and ACE2 induction in the inflamed colon in a AhR-dependent manner.