COVID-19 and Toll-Like Receptor 4 (TLR4): SARS-CoV-2 May Bind and Activate TLR4 to Increase ACE2 Expression, Facilitating Entry and Causing Hyperinflammation

SARS-CoV-2 superinfection in CD14+ monocytes with latent human cytomegalovirus (HCMV) promotes inflammatory cascade

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiologic agent of coronavirus disease 2019 (COVID-19), has posed significant challenges to global health. While much attention has been directed towards understanding the primary mechanisms of SARS-CoV-2 infection, emerging evidence suggests co-infections or superinfections with other viruses may contribute to increased morbidity and mortality, particularly in severe cases of COVID-19. Among viruses that have been reported in patients with SARS-CoV-2, seropositivity for Human cytomegalovirus (HCMV) is associated with increased COVID-19 risk and hospitalization. HCMV is a ubiquitous beta-herpesvirus with a seroprevalence of 60-90 % worldwide and one of the leading causes of mortality in immunocompromised individuals. The primary sites of latency for HCMV include CD14+ monocytes and CD34+ hematopoietic cells. In this study, we sought to investigate SARS-CoV-2 infection of CD14+ monocytes latently infected with HCMV. We demonstrate that CD14+ cells are susceptible and permissive to SARS-CoV-2 infection and detect subgenomic transcripts indicative of replication. To further investigate the molecular changes triggered by SARS-CoV-2 infection in HCMV-latent CD14+ monocytes, we conducted RNA sequencing coupled with bioinformatic differential gene analysis. The results revealed significant differences in cytokine-cytokine receptor interactions and inflammatory pathways in cells superinfected with replication-competent SARS-CoV-2 compared to the heat-inactivated and mock controls. Notably, there was a significant upregulation in transcripts associated with pro-inflammatory response factors and a decrease in anti-inflammatory factors. Taken together, these findings provide a basis for the heightened inflammatory response, offering potential avenues for targeted therapeutic interventions among HCMV-infected severe cases of COVID-19. SUMMARY: COVID-19 patients infected with secondary viruses have been associated with a higher prevalence of severe symptoms. Individuals seropositive for human cytomegalovirus (HCMV) infection are at an increased risk for severe COVID-19 disease and hospitalization. HCMV reactivation has been reported in severe COVID-19 cases with respiratory failure and could be the result of co-infection with SARS-CoV-2 and HCMV. In a cell culture model of superinfection, HCMV has previously been shown to increase infection of SARS-CoV-2 of epithelial cells by upregulating the human angiotensin-converting enzyme-2 (ACE2) receptor. In this study, we utilize CD14+ monocytes, a major cell type that harbors latent HCMV, to investigate co-infection of SARS-CoV-2 and HCMV. This study is a first step toward understanding the mechanism that may facilitate increased COVID-19 disease severity in patients infected with SARS-CoV-2 and HCMV.

Xiaoer niuhuang qingxin powder alleviates influenza a virus infection by inhibiting the activation of the TLR4/MyD88/NF-κB signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Xiaoer Niuhuang Qingxin Powder (XNQP) is a classic traditional Chinese medicine formula with significant clinical efficacy for treating febrile convulsions and influenza.

AIM OF THE STUDY

This study aims to explore the potential mechanisms of XNQP in combating combating the influenza A virus, providing a theoretical basis for its clinical application.

MATERIALS AND METHODS

The present investigation employed network pharmacology and bioinformatics analysis to determine the TLR4/MyD88/NF-κB signaling pathway as a viable target for XNQP intervention in IAV infection.Subsequently, a mouse model of influenza A virus infection was established, and different doses of XNQP were used for intervention. The protein expression levels of TLR4/MyD88/NF-κB were detected using HE staining, Elisa, immunohistochemistry, immunofluorescence, and western blot.

RESULTS

The results showed that treatment with XNQP after IAV infection reduced the mortality and prolonged the survival time of infected mice. It reduced the release of TNF-α and IFN-γ in the serum and alleviated pathological damage in the lung tissue following infection. Additionally, the levels of TLR4, MyD88, NF-κB, and p-NF-κB P65 proteins were significantly reduced in lung tissue by XNQP. The inhibitory effect of XNQP on the expression of MyD88 and NF-κB was antagonized when TLR4 signaling was overexpressed. Consequently, the expression levels of MyD88, NF-κB, and p-NF-κB P65 were increased in lung tissue. Conversely, the expression levels of the proteins MyD88, NF-κB, and p-NF-κB P65 were downregulated when TLR4 signaling was inhibited.

CONCLUSIONS

XNQP alleviated lung pathological changes, reduced serum levels of inflammatory factors, reduced mortality, and prolonged survival time in mice by inhibiting the overexpression of the TLR4/MyD88/NF-κB signaling pathway in lung tissues after IAV infection.

The rs11684747 and rs55790676 SNPs of ADAM17 influence tuberculosis susceptibility and plasma levels of TNF, TNFR1, and TNFR2

Introduction

The proteolytic activity of A Disintegrin and Metalloproteinase 17 (ADAM17) regulates the release of tumor necrosis factor (TNF) and TNF receptors (TNFRs) from cell surfaces. These molecules play important roles in tuberculosis (TB) shaping innate immune reactions and granuloma formation.

Methods

Here, we investigated whether single nucleotide polymorphisms (SNPs) of ADAM17 influence TNF and TNFRs levels in 224 patients with active TB (ATB) and 118 healthy close contacts. Also, we looked for significant associations between SNPs of ADAM17 and ATB status. TNF, TNFR1, and TNFR2 levels were measured in plasma samples by ELISA. Four SNPs of ADAM17 (rs12692386, rs1524668, rs11684747, and rs55790676) were analyzed in DNA isolated from peripheral blood leucocytes. The association between ATB status, genotype, and cytokines was analyzed by multiple regression models.

Results

Our results showed a higher frequency of rs11684747 and rs55790676 in close contacts than ATB patients. Coincidentally, heterozygous to these SNPs of ADAM17 showed higher plasma levels of TNF compared to homozygous to their respective ancestral alleles. Strikingly, the levels of TNF and TNFRs distinguished participant groups, with ATB patients displaying lower TNF and higher TNFR1/TNFR2 levels compared to their close contacts.

Conclusion

These findings suggest a role for SNPs of ADAM17 in genetic susceptibility to ATB.

TLR2/4 are novel activating receptors for SARS-CoV-2 spike protein on NK cells

Background

In early infected or severe coronavirus disease 2019 (COVID-19) patients, circulating NK cells are consistently reduced, despite being highly activated or exhausted. The aim of this paper was to establish whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike glycoprotein (SP) may directly trigger NK cells and through which receptor(s).

Methods

SP-stimulated human NK cells have been evaluated for the expression of activation markers, cytokine release, and cytotoxic activity, as well as for gene expression profiles and NF-kB phosphorylation, and they have been silenced with specific small interfering RNAs.

Results

SPs from the Wuhan strain and other variants of concern (VOCs) directly bind and stimulate purified NK cells by increasing activation marker expression, cytokine release, and cytolytic activity, prevalently in the CD56brightNK cell subset. VOC-SPs differ in their ability to activate NK cells, G614, and Delta-Plus strains providing the strongest activity in the majority of donors. While VOC-SPs do not trigger ACE2, which is not expressed on NK cells, or other activating receptors, they directly and variably bind to both Toll-like receptor 2 (TLR2) and TLR4. Moreover, SP-driven NK cell functions are inhibited upon masking such receptors or silencing the relative genes. Lastly, VOC-SPs upregulate CD56dimNK cell functions in COVID-19 recovered, but not in non-infected, individuals.

Conclusions

TLR2 and TLR4 are novel activating receptors for SP in NK cells, suggesting a new role of these cells in orchestrating the pathophysiology of SARS-CoV-2 infection. The pathogenic relevance of this finding is highlighted by the fact that free SP providing NK cell activation is frequently detected in a SARS-CoV-2 inflamed environment and in plasma of infected and long-COVID-19 subjects.

Diverse roles of SARS-CoV-2 Spike and Nucleocapsid proteins in EndMT stimulation through the TGF-β-MRTF axis inhibited by aspirin

BACKGROUND

The SARS-CoV-2 virus causes severe COVID-19 in one-fifth of patients. In addition to high mortality, infection may induce respiratory failure and cardiovascular complications associated with inflammation. Acute or prolonged inflammation results in organ fibrosis, the cause of which might be endothelial disorders arising during the endothelial-mesenchymal transition (EndMT).

METHODS

HUVECs and HMEC-1 cells were stimulated with SARS-CoV-2 S (Spike) and N (Nucleocapsid) proteins, and EndMT induction was evaluated by studying specific protein markers via Western blotting. Wound healing and tube formation assays were employed to assess the potential of SARS-CoV-2 to stimulate changes in cell behaviour. MRTF nuclear translocation, ROS generation, TLR4 inhibitors, TGF-β-neutralizing antibodies, and inhibitors of the TGF-β-dependent pathway were used to investigate the role of the TGF-β-MRTF signalling axis in SARS-CoV-2-dependent EndMT stimulation.

RESULTS

Both viral proteins stimulate myofibroblast trans-differentiation. However, the N protein is more effective at EndMT induction. The TGF-β-MRTF pathway plays a critical role in this process. The N protein preferentially favours action through TGF-β2, whose secretion is induced through TLR4-ROS action. TGF-β2 stimulates MRTF-A and MRTF-B nuclear translocation and strongly regulates EndMT. In contrast, the Spike protein stimulates TGF-β1 secretion as a result of ACE2 downregulation. TGF-β1 induces only MRTF-B, which, in turn, weakly regulates EndMT. Furthermore, aspirin, a common nonsteroidal anti-inflammatory drug, might prevent and reverse SARS-CoV-2-dependent EndMT induction through TGF-β-MRTF pathway deregulation.

CONCLUSION

The reported study revealed that SARS-CoV-2 infection induces EndMT. Moreover, it was demonstrated for the first time at the molecular level that the intensity of the EndMT triggered by SARS-CoV-2 infection may vary and depend on the viral protein involved. The N protein acts through TLR4-ROS-TGF-β2-MRTF-A/B, whereas the S protein acts through ACE2-TGF-β1-MRTF-B. Furthermore, we identified aspirin as a potential anti-fibrotic drug for treating patients with SARS-CoV-2 infection.

Sex-related immunity: could Toll-like receptors be the answer in acute inflammatory response?

An increasing number of studies have highlighted the existence of a sex-specific immune response, wherein men experience a worse prognosis in cases of acute inflammatory diseases. Initially, this sex-dependent inflammatory response was attributed to the influence of sex hormones. However, a growing body of evidence has shifted the focus toward the influence of chromosomes rather than sex hormones in shaping these inflammatory sex disparities. Notably, certain pattern recognition receptors, such as Toll-like receptors (TLRs), and their associated immune pathways have been implicated in driving the sex-specific immune response. These receptors are encoded by genes located on the X chromosome. TLRs are pivotal components of the innate immune system, playing crucial roles in responding to infectious diseases, including bacterial and viral pathogens, as well as trauma-related conditions. Importantly, the TLR-mediated inflammatory responses, as indicated by the production of specific proteins and cytokines, exhibit discernible sex-dependent patterns. In this review, we delve into the subject of sex bias in TLR activation and explore its clinical implications relatively to both the X chromosome and the hormonal environment. The overarching objective is to enhance our understanding of the fundamental mechanisms underlying these sex differences.

SCARLET (Supplemental Citicoline Administration to Reduce Lung injury Efficacy Trial): study protocol for a single-site, double-blinded, placebo-controlled, and randomized Phase 1/2 trial of i.v. citicoline (CDP-choline) in hospitalized SARS CoV-2-infected patients with hypoxemic acute respiratory failure

BACKGROUND

The SARS CoV-2 pandemic has resulted in more than 1.1 million deaths in the USA alone. Therapeutic options for critically ill patients with COVID-19 are limited. Prior studies showed that post-infection treatment of influenza A virus-infected mice with the liponucleotide CDP-choline, which is an essential precursor for de novo phosphatidylcholine synthesis, improved gas exchange and reduced pulmonary inflammation without altering viral replication. In unpublished studies, we found that treatment of SARS CoV-2-infected K18-hACE2-transgenic mice with CDP-choline prevented development of hypoxemia. We hypothesize that administration of citicoline (the pharmaceutical form of CDP-choline) will be safe in hospitalized SARS CoV-2-infected patients with hypoxemic acute respiratory failure (HARF) and that we will obtain preliminary evidence of clinical benefit to support a larger Phase 3 trial using one or more citicoline doses.

METHODS

We will conduct a single-site, double-blinded, placebo-controlled, and randomized Phase 1/2 dose-ranging and safety study of Somazina® citicoline solution for injection in consented adults of any sex, gender, age, or ethnicity hospitalized for SARS CoV-2-associated HARF. The trial is named "SCARLET" (Supplemental Citicoline Administration to Reduce Lung injury Efficacy Trial). We hypothesize that SCARLET will show that i.v. citicoline is safe at one or more of three doses (0.5, 2.5, or 5 mg/kg, every 12 h for 5 days) in hospitalized SARS CoV-2-infected patients with HARF (20 per dose) and provide preliminary evidence that i.v. citicoline improves pulmonary outcomes in this population. The primary efficacy outcome will be the SpO2:FiO2 ratio on study day 3. Exploratory outcomes include Sequential Organ Failure Assessment (SOFA) scores, dead space ventilation index, and lung compliance. Citicoline effects on a panel of COVID-relevant lung and blood biomarkers will also be determined.

DISCUSSION

Citicoline has many characteristics that would be advantageous to any candidate COVID-19 therapeutic, including safety, low-cost, favorable chemical characteristics, and potentially pathogen-agnostic efficacy. Successful demonstration that citicoline is beneficial in severely ill patients with SARS CoV-2-induced HARF could transform management of severely ill COVID patients.

TRIAL REGISTRATION

The trial was registered at www.

CLINICALTRIALS

gov on 5/31/2023 (NCT05881135).

TRIAL STATUS

Currently enrolling.

Comparative analysis of oropharyngeal microbiota in healthcare workers post-COVID-19

Background

To date, more than 770 million individuals have become coronavirus disease 2019 (COVID-19) convalescents worldwide. Emerging evidence highlights the influence of COVID-19 on the oral microbiome during both acute and convalescent disease phases. Front-line healthcare workers are at an elevated risk of exposure to viral infections, and the effects of COVID-19 on their oral microbiome remain relatively unexplored.

Methods

Oropharyngeal swab specimens, collected one month after a negative COVID-19 test from a cohort comprising 55 healthcare workers, underwent 16S rRNA sequencing. We conducted a comparative analysis between this post-COVID-19 cohort and the pre-infection dataset from the same participants. Community composition analysis, indicator species analysis, alpha diversity assessment, beta diversity exploration, and functional prediction were evaluated.

Results

The Shannon and Simpson indexes of the oral microbial community declined significantly in the post-COVID-19 group when compared with the pre-infection cohort. Moreover, there was clear intergroup clustering between the two groups. In the post-COVID-19 group, the phylum Firmicutes showed a significant increase. Further, there were clear differences in relative abundance of several bacterial genera in contrast with the pre-infection group, including Streptococcus, Gemella, Granulicatella, Capnocytophaga, Leptotrichia, Fusobacterium, and Prevotella. We identified Gemella enrichment in the post-COVID-19 group, potentially serving as a recovery period performance indicator. Functional prediction revealed lipopolysaccharide biosynthesis downregulation in the post-COVID-19 group, an outcome with host inflammatory response modulation and innate defence mechanism implications.

Conclusion

During the recovery phase of COVID-19, the oral microbiome diversity of front-line healthcare workers failed to fully return to its pre-infection state. Despite the negative COVID-19 test result one month later, notable disparities persisted in the composition and functional attributes of the oral microbiota.

In Silico Analyses Indicate a Lower Potency for Dimerization of TLR4/MD-2 as the Reason for the Lower Pathogenicity of Omicron Compared to Wild-Type Virus and Earlier SARS-CoV-2 Variants

The SARS-CoV-2 Omicron variants have replaced all earlier variants, due to increased infectivity and effective evasion from infection- and vaccination-induced neutralizing antibodies. Compared to earlier variants of concern (VoCs), the Omicron variants show high TMPRSS2-independent replication in the upper airway organs, but lower replication in the lungs and lower mortality rates. The shift in cellular tropism and towards lower pathogenicity of Omicron was hypothesized to correlate with a lower toll-like receptor (TLR) activation, although the underlying molecular mechanisms remained undefined. In silico analyses presented here indicate that the Omicron spike protein has a lower potency to induce dimerization of TLR4/MD-2 compared to wild type virus despite a comparable binding activity to TLR4. A model illustrating the molecular consequences of the different potencies of the Omicron spike protein vs. wild-type spike protein for TLR4 activation is presented. Further analyses indicate a clear tendency for decreasing TLR4 dimerization potential during SARS-CoV-2 evolution via Alpha to Gamma to Delta to Omicron variants.

Vitamin D regulates COVID-19 associated severity by suppressing the NLRP3 inflammasome pathway

BACKGROUND

The role of vitamin D3 (VitD3) in modulating innate and adaptive immunity has been reported in different disease contexts. Since the start of the coronavirus disease-2019 (COVID-19) pandemic, the role of VitD3 has been highlighted in many correlational and observational studies. However, the exact mechanisms of action are not well identified. One of the mechanisms via which VitD3 modulates innate immunity is by regulating the NLRP3-inflammasome pathway, being a main underlying cause of SARS-CoV-2-induced hyperinflammation.

AIMS AND MAIN METHODS

Blood specimens of severe COVID-19 patients with or without VitD3 treatment were collected during their stay in the intensive care unit and patients were followed up for 29 days. qPCR, western blot, and ELISA were done to investigate the mechanism of action of VitD3 on the NLRP3 inflammasome activation.

KEY FINDINGS

We here report the ability of VitD3 to downregulate the NLRP3-inflammsome pathway in severe COVID-19 patients. Lower inflammasome pathway activation was observed with significantly lower gene and protein expression of NLRP3, cleaved caspase-1, ASC and IL-1β among severe COVID-19 patients treated with VitD3. The reduction of the inflammasome pathway was associated with a reduction in disease severity markers and enhancement of type I IFN pathway.

SIGNIFICANCE

Our data reveals an important anti-inflammatory effect of VitD3 during SARS-CoV-2 infection. Further investigations are warranted to better characterize the ability of VitD3 to control disease pathogenesis and prevent progression to severe states. This will allow for a more efficient use of a low cost and accessible treatment like VitD3.

Unique Synthetic Strategy for Probing in Situ Lysosomal NO for Screening Neuroinflammatory Phenotypes against SARS-CoV-2 RNA in Phagocytotic Microglia

In the pathogenesis of microglia, brain immune cells promote nitrergic stress by overproducing nitric oxide (NO), leading to neuroinflammation. Furthermore, NO has been linked to COVID-19 progression, which has caused significant morbidity and mortality. SARS-CoV-2 infection activates inflammation by releasing excess NO and causing cell death in human microglial clone 3 (HMC3). In addition, NO regulates lysosomal functions and complex machinery to neutralize pathogens through phagocytosis. Therefore, developing lysosome-specific NO probes to monitor phagocytosis in microglia during the COVID-19 infection would be a significant study. Herein, a unique synthetic strategy was adopted to develop a NO selective fluorescent probe, PDM-NO, which can discriminate activated microglia from their resting state. The nonfluorescent PDM-NO exhibits a turn-on response toward NO only at lysosomal pH (4.5-5.5). Quantum chemical calculations (DFT/TD-DFT/PCM) and photophysical study revealed that the photoinduced electron transfer (PET) process is pivotal in tuning optical properties. PDM-NO demonstrated good biocompatibility and lysosomal specificity in activated HMC3 cells. Moreover, it can effectively map the dynamics of lysosomal NO against SARS-CoV-2 RNA-induced neuroinflammation in HMC3. Thus, PDM-NO is a potential fluorescent marker for detecting RNA virus infection and monitoring phagocytosis in HMC3.

Tumor-necrosis factor α-rich environment alters type-I interferon response to viral stimuli in patients with juvenile idiopathic arthritis by altering myeloid dendritic cell phenotype

The balance between the tumor-necrosis factor α (TNFα) and type-I interferon (T1IFN) pathways is crucial for proper immune function. Dysregulation of either pathway can contribute to autoimmune diseases development. Even though TNFα blockade has shown promising results in various autoimmune diseases, the effect on the balance between TNFα and T1IFN is elusive. We used targeted anti-TNFα therapies in juvenile idiopathic arthritis (JIA) as an experimental approach to study the cross-regulation between TNFα and type-I IFN. We found that TNFα-rich environment affected viral defense through the attenuation of T1IFN responses and affected the phenotype and distribution of myeloid dendritic cells, which are engaged in early viral infections. Anti-TNFα therapy normalized the observed deviations in JIA patients. We hypothesize that the inadequate immune response caused by a high TNFα environment could be projected to more frequent or lengthy viral infections and possibly play a role in the process of JIA disease development.

Design of a novel multi-epitope vaccine candidate against Chlamydia trachomatis using structural and nonstructural proteins: an immunoinformatics study

Chlamydia trachomatis (C. trachomatis) is an obligate intracellular bacterium which causes eye and sexually transmitted infections. During pregnancy, the bacterium is associated with preterm complications, low weight of neonates, fetal demise and endometritis leading to infertility. The aim of our study was design of a multi-epitope vaccine (MEV) candidate against C. trachomatis. After protein sequence adoption from the NCBI, potential epitopes toxicity, antigenicity, allergenicity, MHC-I and MHC-II binding, cytotoxic T lymphocytes (CTLs), Helper T lymphocytes (HTLs) and interferon-γ (IFN-γ)- induction were predicted. The adopted epitopes were fused together using appropriate linkers. In the next step, the MEV structural mapping and characterization, three-dimensional (3D) structure homology modeling and refinement were also performed. The MEV candidate interaction with the toll-like receptor 4 (TLR4) was also docked. The immune responses simulation was assessed using the C-IMMSIM server. Molecular dynamic (MD) simulation verified the structural stability of the TLR4-MEV complex. The Molecular Mechanics Poisson-Boltzmann Surface Area (MMPBSA) approach demonstrated the MEV high affinity of binding to the TLR4, MHC-I and MHC-II. The MEV construct was also stable and water soluble and had enough antigenicity and lacked allergenicity with stimulation of T cells and B cells and INF-γ release. The immune simulation confirmed acceptable responses of both the humoral and cellular arms. It is proposed that in vitro and in vivo studies are needed to evaluate the findings of this study.Communicated by Ramaswamy H. Sarma.

The role of neuroinflammation in neurodegenerative diseases: current understanding and future therapeutic targets

Neuroinflammation refers to a highly complicated reaction of the central nervous system (CNS) to certain stimuli such as trauma, infection, and neurodegenerative diseases. This is a cellular immune response whereby glial cells are activated, inflammatory mediators are liberated and reactive oxygen and nitrogen species are synthesized. Neuroinflammation is a key process that helps protect the brain from pathogens, but inappropriate, or protracted inflammation yields pathological states such as Parkinson's disease, Alzheimer's, Multiple Sclerosis, and other neurodegenerative disorders that showcase various pathways of neurodegeneration distributed in various parts of the CNS. This review reveals the major neuroinflammatory signaling pathways associated with neurodegeneration. Additionally, it explores promising therapeutic avenues, such as stem cell therapy, genetic intervention, and nanoparticles, aiming to regulate neuroinflammation and potentially impede or decelerate the advancement of these conditions. A comprehensive understanding of the intricate connection between neuroinflammation and these diseases is pivotal for the development of future treatment strategies that can alleviate the burden imposed by these devastating disorders.

Severe pediatric COVID-19: a review from the clinical and immunopathophysiological perspectives

BACKGROUND

Coronavirus disease 2019 (COVID-19) tends to have mild presentations in children. However, severe and critical cases do arise in the pediatric population with debilitating systemic impacts and can be fatal at times, meriting further attention from clinicians. Meanwhile, the intricate interactions between the pathogen virulence factors and host defense mechanisms are believed to play indispensable roles in severe COVID-19 pathophysiology but remain incompletely understood.

DATA SOURCES

A comprehensive literature review was conducted for pertinent publications by reviewers independently using the PubMed, Embase, and Wanfang databases. Searched keywords included "COVID-19 in children", "severe pediatric COVID-19", and "critical illness in children with COVID-19".

RESULTS

Risks of developing severe COVID-19 in children escalate with increasing numbers of co-morbidities and an unvaccinated status. Acute respiratory distress stress and necrotizing pneumonia are prominent pulmonary manifestations, while various forms of cardiovascular and neurological involvement may also be seen. Multiple immunological processes are implicated in the host response to COVID-19 including the type I interferon and inflammasome pathways, whose dysregulation in severe and critical diseases translates into adverse clinical manifestations. Multisystem inflammatory syndrome in children (MIS-C), a potentially life-threatening immune-mediated condition chronologically associated with COVID-19 exposure, denotes another scientific and clinical conundrum that exemplifies the complexity of pediatric immunity. Despite the considerable dissimilarities between the pediatric and adult immune systems, clinical trials dedicated to children are lacking and current management recommendations are largely adapted from adult guidelines.

CONCLUSIONS

Severe pediatric COVID-19 can affect multiple organ systems. The dysregulated immune pathways in severe COVID-19 shape the disease course, epitomize the vast functional diversity of the pediatric immune system and highlight the immunophenotypical differences between children and adults. Consequently, further research may be warranted to adequately address them in pediatric-specific clinical practice guidelines.

Variant- and vaccination-specific alternative splicing profiles in SARS-CoV-2 infections

The COVID-19 pandemic, driven by the SARS-CoV-2 virus and its variants, highlights the important role of understanding host-viral molecular interactions influencing infection outcomes. Alternative splicing post-infection can impact both host responses and viral replication. We analyzed RNA splicing patterns in immune cells across various SARS-CoV-2 variants, considering immunization status. Using a dataset of 190 RNA-seq samples from our prior studies, we observed a substantial deactivation of alternative splicing and RNA splicing-related genes in COVID-19 patients. The alterations varied significantly depending on the infecting variant and immunization history. Notably, Alpha or Beta-infected patients differed from controls, while Omicron-infected patients displayed a splicing profile closer to controls. Particularly, vaccinated Omicron-infected individuals showed a distinct dynamic in alternative splicing patterns not widely shared among other groups. Our findings underscore the intricate interplay between SARS-CoV-2 variants, vaccination-induced immunity, and alternative splicing, emphasizing the need for further investigations to deepen understanding and guide therapeutic development.

NFκB and NLRP3/NLRC4 inflammasomes regulate differentiation, activation and functional properties of monocytes in response to distinct SARS-CoV-2 proteins

Increased recruitment of transitional and non-classical monocytes in the lung during SARS-CoV-2 infection is associated with COVID-19 severity. However, whether specific innate sensors mediate the activation or differentiation of monocytes in response to different SARS-CoV-2 proteins remain poorly characterized. Here, we show that SARS-CoV-2 Spike 1 but not nucleoprotein induce differentiation of monocytes into transitional or non-classical subsets from both peripheral blood and COVID-19 bronchoalveolar lavage samples in a NFκB-dependent manner, but this process does not require inflammasome activation. However, NLRP3 and NLRC4 differentially regulated CD86 expression in monocytes in response to Spike 1 and Nucleoprotein, respectively. Moreover, monocytes exposed to Spike 1 induce significantly higher proportions of Th1 and Th17 CD4 + T cells. In contrast, monocytes exposed to Nucleoprotein reduce the degranulation of CD8 + T cells from severe COVID-19 patients. Our study provides insights in the differential impact of innate sensors in regulating monocytes in response to different SARS-CoV-2 proteins, which might be useful to better understand COVID-19 immunopathology and identify therapeutic targets.

SARS-CoV-2 Omicron Spike shows strong binding affinity and favourable interaction landscape with the TLR4/MD2 compared to other variants

Emergences of SARS-CoV-2 variants have made the pandemic more critical. Toll-like receptor 4 (TLR4) recognizes the molecular patterns of pathogens and activates the production of proinflammatory cytokines to restrain the infection. We have identified a molecular basis of interaction between the Spike and TLR4 of SARS-CoV-2 and its present and past VOCs (variant- of concern) through in silico analysis. The interaction of wild type Spike with TLR4 showed 15 number hydrogen bonds formation. Similarly, the Alpha variants' Spike with the TLR4 has illustrated that 14 hydrogen bonds participated in the interaction. However, the Delta Spike and TLR4 interaction interface showed that 17 hydrogen bonds were formed during the interaction. Furthermore, Omicron S-glycoprotein and TLR4 interaction interface was depicted (interaction score: -170.3), and 16 hydrogen bonds were found to have been formed in the interaction. Omicron S-glycoprotein shows stronger binding affinity with the TLR4 than wild type, Alpha, and Delta variants. Similarly, the Alpha Spike shows higher binding affinity with TLR4 than the wild type and Delta variant. Now, it is an open question of the molecular basis of the interaction of Spike and TLR4 and the activated downstream signaling events of TLR4 for SARS-CoV-2 and its variants.

Immune Epitopes of SARS-CoV-2 Spike Protein and Considerations for Universal Vaccine Development

Despite the success of global vaccination programs in slowing the spread of COVID-19, these efforts have been hindered by the emergence of new SARS-CoV-2 strains capable of evading prior immunity. The mutation and evolution of SARS-CoV-2 have created a demand for persistent efforts in vaccine development. SARS-CoV-2 Spike protein has been the primary target for COVID-19 vaccine development, but it is also the hotspot of mutations directly involved in host susceptibility and virus immune evasion. Our ability to predict emerging mutants and select conserved epitopes is critical for the development of a broadly neutralizing therapy or a universal vaccine. In this article, we review the general paradigm of immune responses to COVID-19 vaccines, highlighting the immunological epitopes of Spike protein that are likely associated with eliciting protective immunity resulting from vaccination in humans. Specifically, we analyze the structural and evolutionary characteristics of the SARS-CoV-2 Spike protein related to immune activation and function via the TLRs, B cells, and T cells. We aim to provide a comprehensive analysis of immune epitopes of Spike protein, thereby contributing to the development of new strategies for broad neutralization or universal vaccination.

Mechanisms of endothelial activation, hypercoagulation and thrombosis in COVID-19: a link with diabetes mellitus

Early since the onset of the COVID-19 pandemic, the medical and scientific community were aware of extra respiratory actions of SARS-CoV-2 infection. Endothelitis, hypercoagulation, and hypofibrinolysis were identified in COVID-19 patients as subsequent responses of endothelial dysfunction. Activation of the endothelial barrier may increase the severity of the disease and contribute to long-COVID syndrome and post-COVID sequelae. Besides, it may cause alterations in primary, secondary, and tertiary hemostasis. Importantly, these responses have been highly decisive in the evolution of infected patients also diagnosed with diabetes mellitus (DM), who showed previous endothelial dysfunction. In this review, we provide an overview of the potential triggers of endothelial activation related to COVID-19 and COVID-19 under diabetic milieu. Several mechanisms are induced by both the viral particle itself and by the subsequent immune-defensive response (i.e., NF-κB/NLRP3 inflammasome pathway, vasoactive peptides, cytokine storm, NETosis, activation of the complement system). Alterations in coagulation mediators such as factor VIII, fibrin, tissue factor, the von Willebrand factor: ADAMST-13 ratio, and the kallikrein-kinin or plasminogen-plasmin systems have been reported. Moreover, an imbalance of thrombotic and thrombolytic (tPA, PAI-I, fibrinogen) factors favors hypercoagulation and hypofibrinolysis. In the context of DM, these mechanisms can be exacerbated leading to higher loss of hemostasis. However, a series of therapeutic strategies targeting the activated endothelium such as specific antibodies or inhibitors against thrombin, key cytokines, factor X, complement system, the kallikrein-kinin system or NETosis, might represent new opportunities to address this hypercoagulable state present in COVID-19 and DM. Antidiabetics may also ameliorate endothelial dysfunction, inflammation, and platelet aggregation. By improving the microvascular pathology in COVID-19 and post-COVID subjects, the associated comorbidities and the risk of mortality could be reduced.

The Role of Furin in the Pathogenesis of COVID-19-Associated Neurological Disorders

Neurological disorders have been reported in a large number of coronavirus disease 2019 (COVID-19) patients, suggesting that this disease may have long-term adverse neurological consequences. COVID-19 occurs from infection by a positive-sense single-stranded RNA virus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The membrane fusion protein of SARS-CoV-2, the spike protein, binds to its human host receptor, angiotensin-converting enzyme 2 (ACE2), to initiate membrane fusion between the virus and host cell. The spike protein of SARS-CoV-2 contains the furin protease recognition site and its cleavage enhances the infectivity of this virus. The binding of SARS-CoV-2 to the ACE2 receptor has been shown to downregulate ACE2, thereby increasing the levels of pathogenic angiotensin II (Ang II). The furin protease cleaves between the S1 subunit of the spike protein with the binding domain toward ACE2 and the S2 subunit with the transmembrane domain that anchors to the viral membrane, and this activity releases the S1 subunit into the blood circulation. The released S1 subunit of the spike protein also binds to and downregulates ACE2, in turn increasing the level of Ang II. Considering that a viral particle contains many spike protein molecules, furin-dependent cleavage would release many free S1 protein molecules, each of which can downregulate ACE2, while infection with a viral particle only affects one ACE2 molecule. Therefore, the furin-dependent release of S1 protein would dramatically amplify the ability to downregulate ACE2 and produce Ang II. We hypothesize that this amplification mechanism that the virus possesses, but not the infection per se, is the major driving force behind COVID-19-associated neurological disorders.

The single nucleotide polymorphism rs4986790 (c.896A>G) in the gene TLR4 as a protective factor in corona virus disease 2019 (COVID-19)

Background and aims

Several factors, such as hypertension and diabetes mellitus, are known to influence the course of coronavirus disease 2019 (COVID-19). However, there is currently little information on genetic markers that influence the severity of COVID-19. In this study, we specifically investigated the single nucleotide polymorphism (SNP) rs4986790 in the TLR4 gene to identify a universal marker for preclinical prediction of COVID-19 disease progression.

Methods

We analyzed the influence of demographics, pre-existing conditions, inflammatory parameters at the time of hospitalization, and TLR4 rs4986790 genotype on the outcome of COVID-19 in a comprehensive cohort (N = 1570). We performed multivariable analysis to investigate the impact of each factor.

Results

We confirmed that younger patient age and absence of pre-existing conditions were protective factors against disease progression. Furthermore, when comparing patients with mild SARS-CoV-2 infection with patients who required hospitalization or intensive care or even died due to COVID-19, the AG/GG genotype of TLR4 rs4986790 was found to be a protective factor against COVID-19 disease progression (OR: 0.51, 95% CI: 0.34 - 0.77, p = 0.001). In addition, we demonstrated that low levels of interleukin-6 (IL-6) and procalcitonin (PCT) had a favorable effect on COVID-19 disease severity. In the subsequent multivariable analysis, we confirmed the absence of cardiovascular disease, low levels of IL-6 and PCT, and TLR4 rs4986790 AG/GG genotypes as independent predictors of potential hospitalization and reduction of severe or fatal disease course.

Conclusion

In this study, we identified an additional genetic factor that may serve as an invariant predictor of COVID-19 outcome. The TLR4 rs4986790 AG/GG genotype reduced by half the risk of COVID-19 patients requiring hospitalization, intensive care or to have a fatal outcome. In addition, we were able to confirm the influence of previously known factors such as pre-existing conditions and inflammatory markers upon the onset of disease on the course of COVID-19. Based on these observations, we hereby provide another prognostic biomarker that could be used in routine diagnostics as a predictive factor for the severity of COVID-19 prior to SARS-CoV-2 infection.

SARS-CoV-2: A Glance at the Innate Immune Response Elicited by Infection and Vaccination

The COVID-19 pandemic caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has led to almost seven million deaths worldwide. SARS-CoV-2 causes infection through respiratory transmission and can occur either without any symptoms or with clinical manifestations which can be mild, severe or, in some cases, even fatal. Innate immunity provides the initial defense against the virus by sensing pathogen-associated molecular patterns and triggering signaling pathways that activate the antiviral and inflammatory responses, which limit viral replication and help the identification and removal of infected cells. However, temporally dysregulated and excessive activation of the innate immune response is deleterious for the host and associates with severe COVID-19. In addition to its defensive role, innate immunity is pivotal in priming the adaptive immune response and polarizing its effector function. This capacity is relevant in the context of both SARS-CoV-2 natural infection and COVID-19 vaccination. Here, we provide an overview of the current knowledge of the innate immune responses to SARS-CoV-2 infection and vaccination.

Endoplasmic reticulum-associated SARS-CoV-2 ORF3a elicits heightened cytopathic effects despite robust ER-associated degradation

IMPORTANCE

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has tragically claimed millions of lives through coronavirus disease 2019 (COVID-19), and there remains a critical gap in our understanding of the precise molecular mechanisms responsible for the associated fatality. One key viral factor of interest is the SARS-CoV-2 ORF3a protein, which has been identified as a potent inducer of host cellular proinflammatory responses capable of triggering the catastrophic cytokine storm, a primary contributor to COVID-19-related deaths. Moreover, ORF3a, much like the spike protein, exhibits a propensity for frequent mutations, with certain variants linked to the severity of COVID-19. Our previous research unveiled two distinct types of ORF3a mutant proteins, categorized by their subcellular localizations, setting the stage for a comparative investigation into the functional and mechanistic disparities between these two types of ORF3a variants. Given the clinical significance and functional implications of the natural ORF3a mutations, the findings of this study promise to provide invaluable insights into the potential roles undertaken by these mutant ORF3a proteins in the pathogenesis of COVID-19.

Potential Alternative Receptors for SARS-CoV-2-Induced Kidney Damage: TLR-4, KIM-1/TIM-1, and CD147

Kidney damage in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can occur even in patients with no underlying kidney disease. Signs of kidney problems can progress to a state that demands dialysis and hampering recovery. Although not without controversy, emerging evidence implicates direct infectivity of SARS-CoV-2 in the kidney. At the early stage of the pandemic, consideration was mainly on the well-recognized angiotensin-converting enzyme 2 (ACE2) receptor as being the site for viral interaction and subsequent cellular internalization. Despite the abundance of ACE2 receptors in the kidneys, researchers have expanded beyond ACE2 and identified novel viral entry pathways that could be advantageously explored as therapeutic targets. This review presents the potential involvement of toll-like receptor 4 (TLR-4), kidney injury molecule-1/T cell immunoglobulin mucin domain 1 (KIM-1/TIM-1), and cluster of differentiation 147 (CD147) in SARS-CoV-2-associated renal damage. In this context, we address the unresolved issues surrounding SARS-CoV-2 renal infectivity.

PAMPs and DAMPs in Sepsis: A Review of Their Molecular Features and Potential Clinical Implications

Sepsis is a serious organ dysfunction caused by a dysregulated immune host reaction to a pathogen. The innate immunity is programmed to react immediately to conserved molecules, released by the pathogens (PAMPs), and the host (DAMPs). We aimed to review the molecular mechanisms of the early phases of sepsis, focusing on PAMPs, DAMPs, and their related pathways, to identify potential biomarkers. We included studies published in English and searched on PubMed® and Cochrane®. After a detailed discussion on the actual knowledge of PAMPs/DAMPs, we analyzed their role in the different organs affected by sepsis, trying to elucidate the molecular basis of some of the most-used prognostic scores for sepsis. Furthermore, we described a chronological trend for the release of PAMPs/DAMPs that may be useful to identify different subsets of septic patients, who may benefit from targeted therapies. These findings are preliminary since these pathways seem to be strongly influenced by the peculiar characteristics of different pathogens and host features. Due to these reasons, while initial findings are promising, additional studies are necessary to clarify the potential involvement of these molecular patterns in the natural evolution of sepsis and to facilitate their transition into the clinical setting.

Identification of the feature genes involved in cytokine release syndrome in COVID-19

OBJECTIVE

Screening of feature genes involved in cytokine release syndrome (CRS) from the coronavirus disease 19 (COVID-19).

METHODS

The data sets related to COVID-19 were retrieved using Gene Expression Omnibus (GEO) database, the differentially expressed genes (DEGs) related to CRS were analyzed with R software and Venn diagram, and the biological processes and signaling pathways involved in DEGs were analyzed with GO and KEGG enrichment. Core genes were screened using Betweenness and MCC algorithms. GSE164805 and GSE171110 dataset were used to verify the expression level of core genes. Immunoinfiltration analysis was performed by ssGSEA algorithm in the GSVA package. The DrugBank database was used to analyze the feature genes for potential therapeutic drugs.

RESULTS

This study obtained 6950 DEGs, of which 971 corresponded with CRS disease genes (common genes). GO and KEGG enrichment showed that multiple biological processes and signaling pathways associated with common genes were closely related to the inflammatory response. Furthermore, the analysis revealed that transcription factors that regulate these common genes are also involved in inflammatory response. Betweenness and MCC algorithms were used for common gene screening, yielding seven key genes. GSE164805 and GSE171110 dataset validation revealed significant differences between the COVID-19 and normal controls in four core genes (feature genes), namely IL6R, TLR4, TLR2, and IFNG. The upregulated IL6R, TLR4, and TLR2 genes were mainly involved in the Toll-like receptor signaling pathway of the inflammatory pathway, while the downregulated IFNG genes primarily participated in the necroptosis and JAK-STAT signaling pathways. Moreover, immune infiltration analysis indicated that higher expression of these genes was associated with immune cell infiltration that mediates inflammatory response. In addition, potential therapeutic drugs for these four feature genes were identified via the DrugBank database.

CONCLUSION

IL6R, TLR4, TLR2, and IFNG may be potential pathogenic genes and therapeutic targets for the CRS associated with COVID-19.

Methyl 2-[3-(4-hydroxyphenyl)prop-2-enoylamino]-3-phenylpropanoate Is a Potent Cell-Permeable Anti-Cytokine Compound To Inhibit Inflammatory Cytokines in Monocyte/Macrophage-Like Cells

Cytokines are signaling molecules involved in inflammation process. Interleukin (IL)-6 is one of pivotal inflammatory cytokines associated with many human diseases. Therefore, there are on-going efforts to find a therapeutic to inhibit IL-6 and other cytokines. Methyl 2-[3-(4-hydroxyphenyl)prop-2-enoylamino]-3-phenylpropanoate (MHPAP) is a phenolic amide ester, transported better than its non-ester form (NEF) in monocyte/macrophage-like cells. However, there is no information about the effects of their cell permeability on cytokines. Therefore, the effects of MHPAP and NEF on cytokines were investigated in lipopolysaccharide (LPS)-stimulated THP-1 and human peripheral blood mononuclear cells (PBMCs). In the THP-1 cells, MHPAP significantly inhibited IL-6, IL-1beta, IL-8, and tumor necrosis factor (TNF)-alpha (P < 0.05), but NEF showed no effects. MHPAP also inhibited nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) p65 phosphorylation in the THP-1 cells (P < 0.05), without significant effects on c-FOS, ATF-2, and JUN phosphorylations. Because NF-κB p65 is phosphorylated by IκB kinase (IKK), in silico analysis was performed on IKK. MHPAP was found to bind to IKK better than an IKK inhibitor ((E)-2-fluoro-4'-methoxystilbene). Furthermore, MHPAP inhibited the luminescence increased in the LPS-stimulated NF-κB-Luc2 THP-1 cells. As anticipated, MHPAP was also found to inhibit IL-6, IL-1beta, IL-8, and TNF-alpha significantly in LPS-stimulated PBMCs (P < 0.05). Especially, MHPAP inhibited IL-6 and IL-1beta with an IC50 of 0.85 and 0.87 µM, better than IL-8 (1.58 µM) and TNF-alpha (1.22 µM) in the cells. Altogether, the data suggest that cell permeability may have a significant impact on MHPAP's ability to inhibit cytokines and MHPAP may be used as a potent cell-permeable compound to inhibit inflammatory cytokines in monocyte/macrophage-like cells. SIGNIFICANCE STATEMENT: Potential effects of MHPAP and NEF on inflammatory cytokines (IL-6, IL-8, IL-1beta, and TNF-alpha) were investigated in LPS-stimulated THP-1 and PBMCs. Cell transport had a great impact on cytokine inhibition in the cells. MHPAP was also found to inhibit NF-κB pathway, which was supported by in silico and NF-κB reporter (Luc)-THP-1 data. Also, in LPS-stimulated PBMCs, MHPAP significantly inhibited IL-6, IL-1beta, IL-8, and TNF-alpha, suggesting that MHPAP may be a potent cell-permeable compound to inhibit inflammatory cytokines in monocyte/macrophage-like cells.

Mechanisms of SARS-CoV-2 Placental Transmission

The widespread occurrence of SARS-CoV-2 infections and the diverse range of symptoms have placed significant strain on healthcare systems worldwide. Pregnancy has also been affected by COVID-19, with an increased risk of complications and unfavorable outcomes for expectant mothers. Multiple studies indicate that SARS-CoV-2 can infiltrate the placenta, breach its protective barrier, and infect the fetus. Although the precise mechanisms of intrauterine transmission remain unclear, factors such as perinatal infection, macrophages, sexual intercourse, and the virus' interaction with host angiotensin-converting enzyme 2 (ACE2) and neuropilin-1 (NRP-1) proteins appear to play a role in this process. The integrity of the placental barrier fluctuates throughout pregnancy and appears to influence the likelihood of fetal transmission. The expression of placental cell receptors, like ACE2, changes during pregnancy and in response to placental damage. However, due to the consistent presence of others, such as NRP-1, SARS-CoV-2 may potentially enter the fetus at different stages of pregnancy. NRP-1 is also found in macrophages, implicating maternal macrophages and Hofbauer cells as potential routes for viral transmission. Our current understanding of SARS-CoV-2's vertical transmission pathways remains limited. Some researchers question the ACE2-associated transmission model due to the relatively low expression of ACE2 in the placenta. Existing studies investigating perinatal transmission and the impact of sexual intercourse have either involved small sample sizes or lacked statistical significance. This review aims to explore the current state of knowledge regarding the potential mechanisms of COVID-19 vertical transmission, identifying areas where further research is needed to fill the gaps in our understanding.

Variant rs4986790 of toll-like receptor 4 affects the signaling and induces cell dysfunction in patients with severe COVID-19

OBJECTIVES

We investigated the expression of toll-like receptor (TLR)-4 on the cell surface of innate and adaptive cells from patients with COVID-19 carrying the rs4986790 GG genotype in the TLR4 gene and the functional profile of these cells.

METHODS

We included 1169 hospitalized patients with COVID-19. The rs4986790 in TLR4 was identified by real-time polymerase chain reaction. Peripheral blood mononuclear cells were isolated and cultured to evaluate TLR-4 expression on immune cells. Supernatants recovered culture assays were stored, and we measured cytokines and cytotoxic molecules.

RESULTS

We showed that the rs4986790 (GG) was significantly associated (P = 0.0310) with severe COVID-19. Cells of patients with COVID-19 carrying the GG genotype have increased the frequency of monocytes and activated naïve and non-switched B cells positive to TLR-4 when cells are stimulated with lipopolysaccharide and with spike protein of SARS-CoV-2. Also, cells from patients with GG COVID-19 cannot produce pro-inflammatory cytokines after lipopolysaccharide stimulus, but they are high producers of cytotoxic molecules at baseline.

CONCLUSIONS

The rs4986790 GG genotype of the TLR4 is associated with the risk of COVID-19 and acute respiratory distress syndrome. Peripheral blood mononuclear cells of patients carrying the rs4986790 (TLR4) GG genotype had a limited delivery of pro-inflammatory cytokines compared to the AA and AG genotypes in which TLR-4 stimulation induces IL-10, IL-6, tumor necrosis factor-α, and Fas ligand production.

Perspectives on Post-COVID-19 Pulmonary Fibrosis Treatment

Pulmonary fibrosis, a critical outcome of chronic inflammatory diseases, has gained prominence in the context of post-coronavirus (post-COVID-19) complications. This review delves into the multifaceted landscape of post-COVID-19 pulmonary fibrosis, elucidating the intricate molecular mechanisms underlying its pathogenesis and highlighting promising therapeutic avenues. Examining the aftermath of severe acute respiratory syndrome-2 (SARS-CoV-2) infection, the review reveals key signaling pathways implicated in the fibrotic cascade. Drawing parallels with previous coronavirus outbreaks enhances our understanding of the distinctive features of post-COVID-19 fibrosis. Antifibrotic drugs, like pirfenidone and nintedanib, take center stage; their mechanisms of action and potential applications in post-COVID-19 cases are thoroughly explored. Beyond the established treatments, this review investigates emerging therapeutic modalities, including anti-interleukin agents, immunosuppressants, and experimental compounds, like buloxybutide, saracatinib, sirolimus, and resveratrol. Emphasizing the critical importance of early intervention, this review highlights the dynamic nature of post-COVID-19 pulmonary fibrosis research. In conclusion, the synthesis of current knowledge offers a foundation for advancing our approaches to the prevention and treatment of these consequential sequelae of COVID-19.

Microglial Inflammatory Responses to SARS-CoV-2 Infection: A Comprehensive Review

Coronavirus disease 2019 (COVID-19) is primarily a respiratory disease causing a worldwide pandemic in the year of 2019. SARS-CoV-2 is an enveloped, positive-stranded RNA virus that could invade the host through spike protein and exhibits multi-organ effects. The Brain was considered to be a potential target for SARS-CoV-2 infection. Although neuropsychiatric symptoms and cognitive impairments were observed in COVID-19 patients even after recovery the mechanism of action is not well documented. In this review, the contribution of microglia in response to SARS-CoV-2 infection was discussed aiming to design a therapeutic regimen for the management of neuroinflammation and psycho-behavioral alterations. Priming of microglia facilitates the hyper-activation state when it interacts with SARS-CoV-2 known as the 'second hit'. Moreover, the microgliosis produces reactive free radicals and pro-inflammatory cytokines like IL-1β, IFN-γ, and IL-6 which ultimately contribute to a 'cytokine storm', thereby increasing the occurrence of cognitive and neurological dysfunction. It was reported that elevated CCL11 may be responsible for psychiatric disorders and ROS/RNS-induced oxidative stress could promote major depressive disorder (MDD) and phenotypic switching. Additionally, during SARS-CoV-2 infection microglia-CD8+ T cell interaction may have a significant role in neuronal cell death. This cytokine-mediated cellular cross-talking plays a crucial role in pro-inflammatory and anti-inflammatory balance within the COVID-19 patient's brain. Therefore, all these aspects will be taken into consideration for developing novel therapeutic strategies to combat SARS-CoV-2-induced neuroinflammation.

Direct activation of airway sensory C-fibers by SARS-CoV-2 S1 spike protein

Respiratory viral infection can lead to activation of sensory afferent nerves as indicated by the consequential sore throat, sneezing, coughing, and reflex secretions. In addition to causing troubling symptoms, sensory nerve activation likely accelerates viral spreading. The mechanism how viruses activate sensory nerve terminals during infection is unknown. In this study, we investigate whether coronavirus spike protein activates sensory nerves terminating in the airways. We used isolated vagally-innervated mouse trachea-lung preparation for two-photon microscopy and extracellular electrophysiological recordings. Using two-photon Ca2+ imaging, we evaluated a total number of 786 vagal bronchopulmonary nerves in six experiments. Approximately 49% of the sensory fibers were activated by S1 protein (4 μg/mL intratracheally). Extracellular nerve recording showed the S1 protein evoked action potential discharge in sensory C-fibers; of 39 airway C-fibers (one fiber per mouse), 17 were activated. Additionally, Fura-2 Ca2+ imaging was performed on neurons dissociated from vagal sensory ganglia (n = 254 from 22 mice). The result showed that 63% of neurons responded to S1 protein. SARS-CoV-2 S1 protein can lead to direct activation of sensory C-fiber nerve terminals in the bronchopulmonary tract. Direct activation of C-fibers may contribute to coronavirus symptoms, and amplify viral spreading in a population.

Lactobacillus rhamnosus Restores Antiviral Signaling and Attenuates Cytokines Secretion from Human Bronchial Epithelial Cells Exposed to Cigarette Smoke and Infected with SARS-CoV-2

Individuals with chronic obstructive pulmonary disease (COPD) are more susceptible to exacerbation crisis triggered by secondary lung infections due to the dysfunction of antiviral signaling, principally via suppression of IFN-γ. Although the probiotic is known for controlling pulmonary inflammation in COPD, the influence of the Lactobacillus rhamnosus (Lr) on antiviral signaling in bronchial epithelium exposed to cigarette smoke extract (CSE) and viruses, remains unknown. Thus, the present study investigated the Lr effect on the antiviral signaling and the secretion of inflammatory mediators from bronchial epithelial cells (16HBE cells) exposed to CSE and SARS-CoV-2. The 16HBE cells were cultured, treated with Lr, stimulated with CSE, and infected with SARS-CoV-2. The cellular viability was evaluated using the MTT assay and cytotoxicity measured by lactate dehydrogenase (LDH) activity. The viral load, TLR2, TLR3, TLR4, TLR7, TLR8, MAVS, MyD88, and TRIF were quantified using specific PCR. The pro-inflammatory mediators were measured by a multiplex biometric immunoassay, and angiotensin converting enzyme 2 (ACE2) activity, NF-κB, RIG-I, MAD5, and IRF3 were measured using specific ELISA kits. Lr decreased viral load, ACE2, pro-inflammatory mediators, TLR2, TLR4, NF-κB, TLR3, TLR7, and TLR8 as well as TRIF and MyD88 expression in CSE and SARS-CoV-2 -exposed 16HBE cells. Otherwise, RIG-I, MAD5, IRF3, IFN-γ, and the MAVS expression were restored in 16HBE cells exposed to CSE and SARS-CoV-2 and treated with Lr. Lr induces antiviral signaling associated to IFN-γ secreting viral sensors and attenuates cytokine storm associated to NF-κB in bronchial epithelial cells, supporting its emerging role in prevention of COPD exacerbation.

Variant- and Vaccination-Specific Alternative Splicing Profiles in SARS-CoV-2 Infections

The COVID-19 pandemic, caused by the coronavirus SARS-CoV-2, and its subsequent variants has underscored the importance of understanding the host-viral molecular interactions to devise effective therapeutic strategies. A significant aspect of these interactions is the role of alternative splicing in modulating host responses and viral replication mechanisms. Our study sought to delineate the patterns of alternative splicing of RNAs from immune cells across different SARS-CoV-2 variants and vaccination statuses, utilizing a robust dataset of 190 RNA-seq samples from our previous studies, encompassing an average of 212 million reads per sample. We identified a dynamic alteration in alternative splicing and genes related to RNA splicing were highly deactivated in COVID-19 patients and showed variant- and vaccination-specific expression profiles. Overall, Omicron-infected patients exhibited a gene expression profile akin to healthy controls, unlike the Alpha or Beta variants. However, significantly, we found identified a subset of infected individuals, most pronounced in vaccinated patients infected with Omicron variant, that exhibited a specific dynamic in their alternative splicing patterns that was not widely shared amongst the other groups. Our findings underscore the complex interplay between SARS-CoV-2 variants, vaccination-induced immune responses, and alternative splicing, emphasizing the necessity for further investigations into these molecular cross-talks to foster deeper understanding and guide strategic therapeutic development.

Structural insights into ACE2 interactions and immune activation of SARS-CoV-2 and its variants: an in-silico study

The initial interaction between COVID-19 and the human body involves the receptor-binding domain (RBD) of the viral spike protein with the angiotensin-converting enzyme 2 (ACE2) receptor. Likewise, the spike protein can engage with immune-related proteins, such as toll-like receptors (TLRs) and pulmonary surfactant proteins A (SP-A) and D (SP-D), thereby triggering immune responses. In this study, we utilize computational methods to investigate the interactions between the spike protein and TLRs (specifically TLR2 and TLR4), as well as (SP-A) and (SP-D). The study is conducted on four variants of concern (VOC) to differentiate and identify common virus behaviours. An assessment of the structural stability of various variants indicates slight changes attributed to mutations, yet overall structural integrity remains preserved. Our findings reveal the spike protein's ability to bind with TLR4 and TLR2, prompting immune activation. In addition, our in-silico results reveal almost similar docking scores and therefore affinity for both ACE2-spike and TLR4-spike complexes. We demonstrate that even minor changes due to mutations in all variants, surfactant A and D proteins can function as inhibitors against the spike in all variants, hindering the ACE2-RBD interaction.Communicated by Ramaswamy H. Sarma.

Genetic and immunological insights into COVID-19 with acute myocardial infarction: integrated analysis of mendelian randomization, transcriptomics, and clinical samples

Background

Globally, most deaths result from cardiovascular diseases, particularly ischemic heart disease. COVID-19 affects the heart, worsening existing heart conditions and causing myocardial injury. The mechanistic link between COVID-19 and acute myocardial infarction (AMI) is still being investigated to elucidate the underlying molecular perspectives.

Methods

Genetic risk assessment was conducted using two-sample Mendelian randomization (TSMR) to determine the causality between COVID-19 and AMI. Weighted gene co-expression network analysis (WGCNA) and machine learning were used to discover and validate shared hub genes for the two diseases using bulk RNA sequencing (RNA-seq) datasets. Additionally, gene set enrichment analysis (GSEA) and single-cell RNA-seq (scRNA-seq) analyses were performed to characterize immune cell infiltration, communication, and immune correlation of the hub genes. To validate the findings, the expression patterns of hub genes were confirmed in clinical blood samples collected from COVID-19 patients with AMI.

Results

TSMR did not find evidence supporting a causal association between COVID-19 or severe COVID-19 and AMI. In the bulk RNA-seq discovery cohorts for both COVID-19 and AMI, WGCNA's intersection analysis and machine learning identified TLR4 and ABCA1 as significant hub genes, demonstrating high diagnostic and predictive value in the RNA-seq validation cohort. Single-gene GSEA and single-sample GSEA (ssGSEA) revealed immune and inflammatory roles for TLR4 and ABCA1, linked to various immune cell infiltrations. Furthermore, scRNA-seq analysis unveiled significant immune dysregulation in COVID-19 patients, characterized by altered immune cell proportions, phenotypic shifts, enhanced cell-cell communication, and elevated TLR4 and ABCA1 in CD16 monocytes. Lastly, the increased expression of TLR4, but not ABCA1, was validated in clinical blood samples from COVID-19 patients with AMI.

Conclusion

No genetic causal link between COVID-19 and AMI and dysregulated TLR4 and ABCA1 may be responsible for the development of immune and inflammatory responses in COVID-19 patients with AMI.

GRg1 inhibits the TLR4/NF-kB signaling pathway by upregulating miR-216a-5p to reduce growth factors and inflammatory cytokines in DR

BACKGROUND

Diabetic retinopathy (DR) is a common diabetic neurodegenerative disease that affects vision in severe cases. Current therapeutic drugs are ineffective for some patients with severe side effects, and ginsenoside-Rg1 (GRg1) has been shown to protect against DR and may serve as a new potential drug for DR. This study aimed to confirm the protective effect of GRg1 against DR and its molecular mechanism.

METHODS

Human retinal microvascular endothelial cells (hRMECs) and rats were used to construct DR models in vitro and in vivo. Cell proliferation was detected by BrdU assays, the cell cycle was detected by flow cytometry, and TNF-α, IL-6 and IL-1β levels were detected by ELISA. qRT‒PCR, Western blotting and immunohistochemistry were used to detect the expression of related genes and proteins, and angiogenesis assays were used to assess angiogenesis. RIP and RNA pull down assays were used to determine the relationship between miR-216a-5p and TLR4; retinal structure and changes were observed by HE staining and retinal digestive spread assays.

RESULTS

GRg1 effectively inhibited HG-induced hRMEC proliferation, cell cycle progression and angiogenesis and reduced the levels of intracellular inflammatory cytokines and growth factors. HG downregulated the expression of miR-216a-5p and upregulated the expression of TLR4/NF-kB signaling pathway-related proteins. Importantly, GRg1 inhibited TLR4/NF-kB signaling pathway activation by upregulating miR-216a-5p, thereby inhibiting HG-induced cell proliferation, cell cycle progression, angiogenesis, and the production of inflammatory cytokines and growth factors. In addition, animal experiments confirmed the results of the cell experiments.

CONCLUSIONS

GRg1 inhibits TLR4/NF-kB signaling by upregulating miR-216a-5p to reduce growth factors and inflammatory cytokines in DR, providing a potential therapeutic strategy for DR.

A review of the mechanisms of blood-brain barrier disruption during COVID-19 infection

Coronaviruses are prevalent in mammals and birds, including humans and bats, and they often spread through airborne droplets. In humans, these droplets then interact with angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2), which are the main receptors for the SARS-CoV-2 virus. It can infect several organs, including the brain. The blood-brain barrier (BBB) is designed to maintain the homeostatic neural microenvironment of the brain, which is necessary for healthy neuronal activity, function, and stability. It prevents viruses from entering the brain parenchyma and does not easily allow chemicals to pass into the brain while assisting numerous compounds in exiting the brain. The purpose of this review was to examine how COVID-19 influences the BBB along with the mechanisms that indicate the BBB's deterioration. In addition, the cellular mechanism through which SARS-CoV-2 causes BBB destruction by binding to ACE2 was evaluated and addressed. The mechanisms of the immunological reaction that occurs during COVID-19 infection that may contribute to the breakdown of the BBB were also reviewed. It was discovered that the integrity of the tight junction (TJs), basement membrane, and adhesion molecules was damaged during COVID-19 infection, which led to the breakdown of the BBB. Therefore, understanding how the BBB is disrupted by COVID-19 infection will provide an indication of how the SARS-CoV-2 virus is able to reach the central nervous system (CNS). The findings of this research may help in the identification of treatment options for COVID-19 that can control and manage the infection.

Recombinant SARS-CoV-2 Spike Protein and Its Receptor Binding Domain Stimulate Release of Different Pro-Inflammatory Mediators via Activation of Distinct Receptors on Human Microglia Cells

SARS-CoV-2 infects cells via its spike (S) protein binding to its surface receptor angiotensin converting enzyme 2 (ACE2) on target cells and results in acute symptoms involving especially the lungs known as COVID-19. However, increasing evidence indicates that SARS-CoV-2 infection produces neuroinflammation associated with neurological, neuropsychiatric, and cognitive symptoms persists well past the resolution of the infection, known as post-COVID-19 sequalae or long-COVID. The neuroimmune mechanism(s) involved in long-COVID have not been adequately characterized. In this study, we show that recombinant SARS-CoV-2 full-length S protein stimulates release of pro-inflammatory IL-1b, CXCL8, IL-6, and MMP-9 from cultured human microglia via TLR4 receptor activation. Instead, recombinant receptor-binding domain (RBD) stimulates release of TNF-α, IL-18, and S100B via ACE2 signaling. These results provide evidence that SARS-CoV-2 spike protein contributes to neuroinflammation through different mechanisms that may be involved in CNS pathologies associated with long-COVID.

Immune Epitopes of SARS-CoV-2 Spike Protein and Considerations for Universal Vaccine Development

Despite the success of global vaccination programs in slowing the spread of COVID-19, these efforts have been hindered by the emergence of new SARS-CoV-2 strains capable of evading prior immunity. The mutation and evolution of SARS-CoV-2 have created a demand for persistent efforts in vaccine development. SARS-CoV-2 Spike protein has been the primary target for COVID-19 vaccine development, but it is also the hotspot of mutations directly involved in host susceptibility and immune evasion. Our ability to predict emerging mutants and select conserved epitopes is critical for the development of a broadly neutralizing therapy or a universal vaccine. In this article, we review the general paradigm of immune responses to COVID-19 vaccines, highlighting the immunological epitopes of Spike protein that are likely associated with eliciting protective immunity resulting from vaccination. Specifically, we analyze the structural and evolutionary characteristics of the SARS-CoV-2 Spike protein related to immune activation and function via the toll-like receptors (TLRs), B cells, and T cells. We aim to provide a comprehensive analysis of immune epitopes of Spike protein, thereby contributing to the development of new strategies for broad neutralization or universal vaccination.

Cryo-electron microscopy in the fight against COVID-19-mechanism of virus entry

Cryogenic electron microscopy (cryo-EM) and electron tomography (cryo-ET) have become a critical tool for studying viral particles. Cryo-EM has enhanced our understanding of viral assembly and replication processes at a molecular resolution. Meanwhile, in situ cryo-ET has been used to investigate how viruses attach to and invade host cells. These advances have significantly contributed to our knowledge of viral biology. Particularly, prompt elucidations of structures of the SARS-CoV-2 spike protein and its variants have directly impacted the development of vaccines and therapeutic measures. This review discusses the progress made by cryo-EM based technologies in comprehending the severe acute respiratory syndrome coronavirus-2 (SARS-Cov-2), the virus responsible for the devastating global COVID-19 pandemic in 2020 with focus on the SARS-CoV-2 spike protein and the mechanisms of the virus entry and replication.

Mechanism of COVID-19-Induced Cardiac Damage from Patient, In Vitro and Animal Studies

PURPOSE OF REVIEW

Though patient studies have been important for understanding the disease, research done in animals and cell culture complement our knowledge from patient data and provide insight into the mechanism of the disease. Understanding how COVID causes damage to the heart is essential to understanding possible long-term consequences.

RECENT FINDINGS

COVID-19 is primarily a disease that attacks the lungs; however, it is known to have important consequences in many other tissues including the heart. Though myocarditis does occur in some patients, for most cases of cardiac damage, the injury arises from scarring either due to myocardial infarction or micro-infarction. The main focus is on how COVID affects blood flow through the coronaries. We review how endothelial activation leads to a hypercoagulative state in COVID-19. We also emphasize the effects that the cytokine storm can directly have on the regulation of coronary blood flow. Since the main two cell types that can be infected in the heart are pericytes and cardiomyocytes, we further describe the known effects on pericyte function and how that can further lead to microinfarcts within the heart. Though many of these effects are systemic, this review focuses on the consequences on cardiac tissue of this dysregulation and the role that it has in the formation of myocardial scarring.

SARS-CoV-2 suppresses TLR4-induced immunity by dendritic cells via C-type lectin receptor DC-SIGN

SARS-CoV-2 causes COVID-19, an infectious disease with symptoms ranging from a mild cold to severe pneumonia, inflammation, and even death. Although strong inflammatory responses are a major factor in causing morbidity and mortality, superinfections with bacteria during severe COVID-19 often cause pneumonia, bacteremia and sepsis. Aberrant immune responses might underlie increased sensitivity to bacteria during COVID-19 but the mechanisms remain unclear. Here we investigated whether SARS-CoV-2 directly suppresses immune responses to bacteria. We studied the functionality of human dendritic cells (DCs) towards a variety of bacterial triggers after exposure to SARS-CoV-2 Spike (S) protein and SARS-CoV-2 primary isolate (hCoV-19/Italy). Notably, pre-exposure of DCs to either SARS-CoV-2 S protein or a SARS-CoV-2 isolate led to reduced type I interferon (IFN) and cytokine responses in response to Toll-like receptor (TLR)4 agonist lipopolysaccharide (LPS), whereas other TLR agonists were not affected. SARS-CoV-2 S protein interacted with the C-type lectin receptor DC-SIGN and, notably, blocking DC-SIGN with antibodies restored type I IFN and cytokine responses to LPS. Moreover, blocking the kinase Raf-1 by a small molecule inhibitor restored immune responses to LPS. These results suggest that SARS-CoV-2 modulates DC function upon TLR4 triggering via DC-SIGN-induced Raf-1 pathway. These data imply that SARS-CoV-2 actively suppresses DC function via DC-SIGN, which might account for the higher mortality rates observed in patients with COVID-19 and bacterial superinfections.

COVID-associated cystitis: the culprit behind the bladder woes post-COVID infection? A review

PURPOSE

SARS-CoV-2 had a significant impact on public health since its declaration as a pandemic. It is linked to a high rate of multiple organ dysfunction syndrome (MODS) and a slew of long-term symptoms that are yet to be thoroughly investigated. Among these, genitourinary symptoms of an overactive bladder (increased frequency, urgency, and nocturia) have recently been identified and labeled as COVID-associated cystitis (CAC). This current research is performed to review this phenomenon.

METHODS

A literature search was performed in MEDLINE, Cochrane, and Google Scholar databases and 185 articles were obtained in total, including reviews and trials involving CAC, which were screened using various methods, and 42 articles were gathered for the review.

RESULTS

Among its multitude of symptoms, overactive bladder (OAB) leads to poorer outcomes. The inflammatory mediator-based theory and the ACE-2 receptor-based theory are two probable theories for how it harms the bladder urothelium. The expression of ACE-2 receptors during the pathogenesis of CAC warrants further investigation as ACE modulation may reveal more information about COVID-19 complications. Other comorbidities, immunocompromised patients, or patients with a history of urinary tract infections can also exacerbate this condition.

CONCLUSION

The scarce literature collected related to CAC gives us an insight into the symptomatology, pathophysiology, and possible treatment plans. Treatment choices are diverse among COVID-19-afflicted and unaffected patients for treating urinary symptoms which highlights the importance to distinguish between the two. CAC shows greater prevalence and morbidity when linked to other conditions, thereby warranting future developments in it.

DNMT1-mediated DNA methylation in toll-like receptor 4 (TLR4) inactivates NF-κB signal pathway-triggered pyroptotic cell death and cellular inflammation to ameliorate lipopolysaccharides (LPS)-induced osteomyelitis

Toll-like receptor 4 (TLR4) plays a critical role in various human diseases, and was associated with pyroptotic cell death and inflammatory responses. DNA methylation, which has stable and reversible properties, has been reported to alter the expression of target genes, including TLR4. However, the role of methylated TLR4 in osteomyelitis (OM) and the underlying molecular mechanisms remain unclear. RNA sequencing was used to identify differentially expressed genes and associated signaling pathways. RT-qPCR, Western blot, emzyme-linked immunosorbent assay (ELISA), cell counting kit-8 (CCK-8) and LDH assay kit were used to detect mRNA and protein expression of relevant genes, cell viability and the LDH activity, respectively. TLR4 methylation was detected by methylation-specific PCR (MSP) and verified by Chromatin immunoprecipitation (ChIP). Here, we found that DNA methyltransferase-1 (DNMT1)-mediated TLR4 demethylation significantly suppressed lipopolysaccharides (LPS)-induced pyroptosis and inflammatory response by inhibiting the TLR4/nuclear transcription factor-kappa B (NF-κB) axis. First, we confirmed TLR4 as the study target by mRNA transcriptome sequencing analysis, and TLR4 was observably high-expressed in both OM patients and LPS-treated osteoblastic MC3T3-E1. Then, we found that downregulation of DNMT1 blocked TLR4 promoter methylation modification, resulting in upregulation of TLR4. Simultaneously, functional experiments indicated that suppression of TLR4 or overexpression of DNMT1 promoted cell proliferation and inhibited cell pyroptosis and inflammation in LPS-induced MC3T3-E1, while upregulation of TLR4 restored the effects of DNMT1 silencing on OM progression. In addition, TLR4 elevated phosphorylation of IκB-α and NF-κB p65 in the NF-κB signal pathway, and inhibition of TLR4 or the NF-κB inhibitor PDTC reversed the influence of inhibition of DNMT1. In conclusion, our study demonstrated that DNMT1-mediated TLR4 DNA methylation alleviated LPS-induced OM by inhibiting the NF-κB signaling pathway.

Innate immune dysregulation in multisystem inflammatory syndrome in children (MIS-C)

MIS-C is a systemic inflammation disorder with poorly characterised immunopathological mechanisms. We compared changes in the systemic immune response in children with MIS-C (n = 12, 5-13 years) to healthy controls (n = 14, 5-15 years). Analysis was done in whole blood treated with LPS. Expression of CD11b and Toll-like receptor-4 (TLR4) in neutrophils and monocytes were analysed by flow cytometry. Serum cytokines (IL-1β, IL-2, IL-6, IL-8, IL-10, IL-Ira, TNF-α, TNF-β, IFN-Υ, VEGF, EPO and GM-CSF) and mRNA levels of inflammasome molecules (NLRP3, ASC and IL-1β) were evaluated. Subpopulations of lymphocytes (CD3+, CD19+, CD56+, CD4+, CD8+, TCR Vδ1+, TCR Vδ2+) were assessed at basal levels. Absolute counts of neutrophils and NLR were high in children with MIS-C while absolute counts of lymphocytes were low. Children with MIS-C had increased levels of IL-6, IL-10, TNF-β and VEGF serum cytokines at the basal level, and significantly increased TNF-β post-LPS, compared to controls. IL-1RA and EPO decreased at baseline and post-LPS in MIS-C patients compared to controls. The percentage of CD3+ cells, NK cells and Vδ1 was lower while B cells were higher in children with MIS-C than in controls. Dysregulated immune response in children with MIS-C was evident and may be amenable to immunomodulation.

Network pharmacology and molecular docking to scientifically validate the potential mechanism of Lonicerae japonicae flos in the clinical treatment of COVID-19

Using network pharmacology and molecular docking, we predicted the potential mechanisms of Lonicerae japonicae flos (LJF) therapy for COVID-19. A total of 493 component-related targets and 6,233 COVID-19-related genes were identified, and 267 core genes with overlapping of the two types of genes were identified. The target AKT1, CASP3, IL1B, IL6, PTGS2, TNF and JUN were the hub genes in PPI network according to MCODE score. Component-Target analysis showed the close relationship between targets and components. The results of functional enrichment analyses revealed that LJF exerted pharmacological effects on COVID-19 by regulating IL-17 signalling pathway, TNF signalling pathway, AGE-RAGE signalling pathway in diabetic complications, and Toll-like receptor signalling pathway. Finally, molecular docking confirmed a strong binding affinity between the 7 main active components with the hub genes. The findings suggested that beta-sitosterol, kaempferol and luteolin might be the promising leading components due to their good molecular docking scores.

MicroRNA-223 Inhibits Soybean Glycinin- and β-Conglycinin-Induced Apoptosis of IPEC-J2 Cells by Targeting NLRP-3 in the IEL/IPEC-J2 Co-culture System

The apoptosis of intestinal porcine epithelial cells induced by soybean antigen protein allergy is one of the most important mechanisms responsible for enteritis. MicroRNAs (miRNAs) affect the cellular and physiological functions of all multicellular organisms. We hypothesize that microRNA-223 inhibits soybean glycinin- and β-conglycinin-induced apoptosis of intestinal porcine enterocytes (IPEC-J2) by targeting the NLR family pyrin domain containing 3 (NLRP-3). Using the intestinal interepithelial lymphocyte (IEL)/IPEC-J2 co-culture system as an in vitro model, we investigate the role of microRNA-223 in the regulation of soybean glycinin- and β-conglycinin-induced apoptosis. In co-cultured IEL/IPEC-J2 cells incubated with glycinin or β-conglycinin, microRNA-223 decreased NLRP-3, ASC, caspase-1, caspase-3, FAS, BCL-2, and APAF-1 expressions in IPEC-J2 cells; decreased cytokine and cyclooxygenase-2 levels; significantly increased cell activity; and inhibited apoptosis. These data supported a novel antiallergic mechanism to mitigate the sensitization of soybean antigenic protein, which involves the upregulation of microRNA-223-targeting NLRP-3.

Anti-inflammatory effects of dexamethasone in COVID-19 patients: Translational population PK/PD modeling and simulation

Dexamethasone (DEX) given at a dose of 6 mg once-daily for 10 days is a recommended dosing regimen in patients with coronavirus disease 2019 (COVID-19) requiring oxygen therapy. We developed a population pharmacokinetic and pharmacodynamic (PopPK/PD) model of DEX anti-inflammatory effects in COVID-19 and provide simulations comparing the expected efficacy of four dosing regimens of DEX. Nonlinear mixed-effects modeling and simulations were performed using Monolix Suite version 2021R1 (Lixoft, France). Published data for DEX PK in patients with COVID-19 exhibited moderate variability with a clearance of about half that in healthy adults. No accumulation of the drug was expected even with daily oral doses of 12 mg. Indirect effect models of DEX inhibition of TNFα, IL-6, and CRP plasma concentrations were enacted and simulations performed for DEX given at 1.5, 3, 6, and 12 mg daily for 10 days. The numbers of individuals that achieved specified reductions in inflammatory biomarkers were compared among the treatment groups. The simulations indicate the need for 6 or 12 mg daily doses of DEX for 10 days for simultaneous reductions in TNFα, IL-6, and CRP. Possibly beneficial is DEX given at a dose of 12 mg compared to 6 mg. The PopPK/PD model may be useful in the assessment of other anti-inflammatory compounds as well as drug combinations in the treatment of cytokine storms.