Sensing of viral infection and activation of innate immunity by toll-like receptor 3

Comparative transcriptomic analysis of asymptomatic infected and symptomatic nervous necrosis virus infection in the natural state of golden pompano (Trachinotus ovatus)

Viral nervous necrosis is a significant threat to healthy fish culture, characterized by central nervous system and ocular lesions that involve critical immune mechanisms. The aim of this study was to elucidate the immune complexity associated with viral nervous necrosis to enhance understanding of the immune interactions between viral nervous necrosis and Trachinotus ovatus. In this study, bioinformatics techniques were used to analyze differentially expressed genes (DEGs) and immune-disease related pathways in the asymptomatically infected and symptomatic groups following a natural outbreak of viral nervous necrosis, and the DEGs identified in this study differentiated asymptomatically infected from symptomatic individuals, highlighting the importance of the immune response in the progression of the disease. Notably, gene ontology (GO) entries that were significantly upregulated in the brain tissue of the asymptomatically infected group included those related to the cellular response to cycloheximide, which inhibits the de novo synthesis of viral proteins, leading to viral death. The strong correlation between DEGs and immune response in this study clarifies the complex role of immunity in viral nervous necrosis and provides a data base for analyzing specific functions and pathways following outbreaks of this disease.

ATG16L1 WD domain and linker regulates lipid trafficking to maintain plasma membrane integrity to limit influenza virus infection

The non-canonical functions of autophagy protein ATG16L1 are dependent on a C-terminal WD domain. Recent studies show that the WD domain is required for conjugation of LC3 to single membranes during endocytosis and phagocytosis, where it is thought to promote fusion with lysosomes. Studies in cells lacking the WD domain suggest additional roles in the regulation of cytokine receptor recycling and plasma membrane repair. The WD domain also protects mice against lethal influenza virus in vivo. Here, analysis of mice lacking the WD domain (ΔWD) shows enrichment of cholesterol in brain tissue suggesting a role for the WD domain in cholesterol transport. Brain tissue and cells from ΔWD mice showed reduced cholesterol and phosphatidylserine (PS) in the plasma membrane. Cells from ΔWD mice also showed an intracellular accumulation of cholesterol predominantly in late endosomes. Infection studies using IAV suggest that the loss of cholesterol and PS from the plasma membrane in cells from ΔWD mice results in increased endocytosis and nuclear delivery of IAV, as well as increased Ifnb/Ifnβ and Isg15 gene expression. Upregulation of Il6, Ifnb and Isg15 mRNA were observed in "ex vivo" precision cut lung slices from ΔWD mice both at rest and in response to IAV infection. Overall, we present evidence that regulation of lipid transport by the WD domain of ATG16L1 may have downstream implications in attenuating viral infection and limiting lethal cytokine signaling.Abbreviations: BMDM: bone marrow-derived macrophages, CASM: conjugation of ATG8 to single membranes, CCD: coil-coil domain, IAV: influenza virus A, IFIT1: interferon-induced protein with tetratricopeptide repeats 1, IFITM3: interferon induced transmembrane protein 3, IFN: interferon, ISG15: ISG15 ubiquitin-like modifier, LANDO: LC3-associated endocytosis, LAP: LC3-associated phagocytosis, LDL: low density lipoprotein, NP: nucleoprotein, PS: phosphatidylserine, WD: WD40-repeat-containing C-terminal domain, WT: wild type.

Immune response accelerated telomere shortening during early life stage of a passerine bird, the blue tit (Cyanistes caeruleus)

Dealing with infections is a daily challenge for wild animals. Empirical data show an increase in reactive oxygen species (ROS) production during immune response. This could have consequences on telomere length, the end parts of linear chromosomes, commonly used as proxy for good health and ageing. Telomere length dynamics may reflect the costs associated with physiological responses. In this study, immune system of blue tit (Cyanistes caeruleus) nestlings was experimentally challenged through a polyinosinic:polycytidylic acid (poly I:C) injection, a synthetic double-stranded RNA that mimics a virus, activating the pathway of immune response triggered via the toll-like receptors 3. This path is known to form ROS downstream. Immune response was quantified by white cell counts in blood, while brain lipoperoxidation has been evaluated as an indicator of oxidative damage. Finally, individuals' telomere length shortening between days 8 and 15 after hatching was measured in erythrocytes. Challenged nestlings showed increased leukocyte number when compared with control (treated with a saline solution), lower brain lipid peroxidation (likely as a result of a compensatory mechanism after oxidative stress burst) and accelerated telomere shortening. These findings support the 'ageing cost of infections pathway' hypothesis, which supposes a role for infections in quick biological ageing.

MDA5 Is a Major Determinant of Developing Symptoms in Critically Ill COVID-19 Patients

Apart from the skin and mucosal immune barrier, the first line of defense of the human immune system includes MDA5 (ifih1 gene) which acts as a cellular sensor protein for certain viruses including SARS-CoV-2. Upon binding with viral RNA, MDA5 activates cell-intrinsic innate immunity, humoral responses, and MAVS (mitochondrial antiviral signaling). MAVS signaling induces type I and III interferon (IFN) expressions that further induce ISGs (interferon stimulatory genes) expressions to initiate human cell-mediated immune responses and attenuate viral replication. SARS-CoV-2 counteracts by producing NSP1, NSP2, NSP3, NSP5, NSP7, NSP12, ORF3A, ORF9, N, and M protein and directs anti-MDA5 antibody production presumably to antagonize IFN signaling. Furthermore, COVID-19 resembles several diseases that carry anti-MDA5 antibodies and the current COVID-19 vaccines induced anti-MDA5 phenotypes in healthy individuals. GWAS (genome-wide association studies) identified several polymorphisms (SNPs) in the ifih1-ifn pathway genes including rs1990760 in ifih1 that are strongly associated with COVID-19, and the associated risk allele is correlated with reduced IFN production. The genetic association of SNPs in ifih1 and ifih1-ifn pathway genes reinforces the molecular findings of the critical roles of MDA5 in sensing SARS-CoV-2 and subsequently the IFN responses to inhibit viral replication and host immune evasion. Thus, MDA5 or its pathway genes could be targeted for therapeutic development of COVID-19.

Maternal choline supplementation modulates cognition and induces anti-inflammatory signaling in the prefrontal cortices of adolescent rats exposed to maternal immune activation

Maternal infection has long been described as a risk factor for neurodevelopmental disorders, especially autism spectrum disorders (ASD) and schizophrenia. Although many pathogens do not cross the placenta and infect the developing fetus directly, the maternal immune response to them is sufficient to alter fetal neurodevelopment, a phenomenon termed maternal immune activation (MIA). Low maternal choline is also a risk factor for neurodevelopmental disorders, and most pregnant people do not receive enough of it. In addition to its role in neurodevelopment, choline is capable of inducing anti-inflammatory signaling through a nicotinic pathway. Therefore, it was hypothesized that maternal choline supplementation would blunt the neurodevelopmental impact of MIA in offspring through long-term instigation of cholinergic anti-inflammatory signaling. To model MIA in rats, the viral mimetic polyinosinic:polycytidylic acid (poly(I:C)) was used to elicit a maternal antiviral innate immune response in dams both with and without choline supplementation. Offspring were reared to both early and late adolescent stages (postnatal days 28 and 50, respectively), where anxiety-related behaviors and cognition were examined. After behavioral testing, animals were euthanized, and their prefrontal cortices (PFCs) were collected for analysis. MIA offspring demonstrated sex-specific patterns of altered cognition and repetitive behaviors, which were modulated by maternal choline supplementation. Choline supplementation also bolstered anti-inflammatory signaling in the PFCs of MIA animals at both early and late adolescent stages. These findings suggest that maternal choline supplementation may be sufficient to blunt some of the behavioral and neurobiological impacts of inflammatory exposures in utero, indicating that it may be a cheap, safe, and effective intervention for neurodevelopmental disorders.

Engineered Cancer Nanovaccines: A New Frontier in Cancer Therapy

Vaccinations are essential for preventing and treating disease, especially cancer nanovaccines, which have gained considerable interest recently for their strong anti-tumor immune capabilities. Vaccines can prompt the immune system to generate antibodies and activate various immune cells, leading to a response against tumor tissues and reducing the negative effects and recurrence risks of traditional chemotherapy and surgery. To enhance the flexibility and targeting of vaccines, nanovaccines utilize nanotechnology to encapsulate or carry antigens at the nanoscale level, enabling more controlled and precise drug delivery to enhance immune responses. Cancer nanovaccines function by encapsulating tumor-specific antigens or tumor-associated antigens within nanomaterials. The small size of these nanomaterials allows for precise targeting of T cells, dendritic cells, or cancer cells, thereby eliciting a more potent anti-tumor response. In this paper, we focus on the classification of carriers for cancer nanovaccines, the roles of different target cells, and clinically tested cancer nanovaccines, discussing strategies for effectively inducing cytotoxic T lymphocytes responses and optimizing antigen presentation, while also looking ahead to the translational challenges of moving from animal experiments to clinical trials.

Sensing of an HIV-1-Derived Single-Stranded RNA-Oligonucleotide Induces Arginase 1-Mediated Tolerance

Small synthetic oligodeoxynucleotides (ODNs) can mimic microbial nucleic acids by interacting with receptor systems and promoting immunostimulatory activities. Nevertheless, some ODNs can act differently on the plasmacytoid dendritic cell (pDC) subset, shaping their immunoregulatory properties and rendering them suitable immunotherapeutic tools in several clinical settings for treating overwhelming immune responses. We designed HIV-1-derived, DNA- and RNA-based oligonucleotides (gag, pol, and U5 regions) and assessed their activity in conferring a tolerogenic phenotype to pDCs in skin test experiments. RNA-but not DNA-oligonucleotides are capable of inducing tolerogenic features in pDCs. Interestingly, sensing the HIV-1-derived single-stranded RNA-gag oligonucleotide (RNA-gag) requires both TLR3 and TLR7 and the engagement of the TRIF adaptor molecule. Moreover, the induction of a suppressive phenotype in pDCs by RNA-gag is contingent upon the induction and activation of the immunosuppressive enzyme Arginase 1. Thus, our data suggest that sensing of the synthetic RNA-gag oligonucleotide in pDCs can induce a suppressive phenotype in pDCs, a property rendering RNA-gag a potential tool for therapeutic strategies in allergies and autoimmune diseases.

Design and validation of a novel multi-epitopes vaccine against hantavirus

Hantavirus is a member of the order Bunyavirales and an emerging global pathogen. Hantavirus infections have affected millions of people globally based on available epidemiological data and research studies. Hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS) are the two main human diseases associated with hantavirus infections. Hence, efforts are required to develop a potent vaccine against the pathogen. The only vaccine that is in use for hantavirus is an inactivated virus vaccine, "Hantavax", but it failed to produce neutralizing antibodies. Vaccine development is of much importance in dealing with the surge of hantavirus globally. In this study, hantavirus five proteins (N protein, G1 and G2, L protein, and non-structural proteins) were used in NetCTL 1.2 program to predict T-cell epitopes. To predict major histocompatibility complex (MHC) binding alleles, an immune epitope database (IEDB) was used. All predicted epitopes were then investigated for different immunoinformatics analyses such as antigenicity and toxicity analyses. The good water-soluble, non-toxic, probable antigenic, and DRB*0101 binder was selected. A multi-epitopes-based vaccine designing was then done where linkers were used to connect the shortlisted epitopes. In addition, an adjuvant molecule was supplementary to the multi-epitopes peptide to improve the vaccine's immunogenic potential. The final vaccine construct's three-dimensional structure was modeled by ab initio method. The vaccine molecule was then evaluated for its binding potential with TLR-3 immune receptor, which is key for its recognition and processing by the host immune system. Docking studies were performed using HADDOCK software. The best-docked complex was selected and visualized for intermolecular binding and interactions using UCSF Chimera 1.16 software. The findings revealed that the designed vaccine might be a potential vaccine against hantavirus and can be used in experimental animal model testings.Communicated by Ramaswamy H. Sarma.

RNA is a pro-apoptotic target of cisplatin in cancer cell lines and C. elegans

Cisplatin not only targets DNA but also RNA. However, it is largely unknown whether platinated RNA (Pt-RNA) causes apoptosis and thus contributes to the cytotoxic effects of cisplatin. Consequently, cellular RNA was isolated from HepG2 and LS180 cells, exposed to cisplatin, and the resulting Pt-RNA (20 ng Pt/µg RNA) was transfected into these cancer cell lines or used to treat an apoptosis reporter Caenorhabditis elegans (C. elegans) strain (MD701, expressing CED-1::GFP). Cellular and molecular effects of Pt-RNA were evaluated by luminogenic caspase 3/7 assays, PCR array analysis, and fluorescence microscopy-based quantification of apoptosis in C. elegans gonads. Assuming RNA cross-linking (pseudo double-stranded RNA), the contribution of the Toll-like receptor 3 (TLR3, a sensor of double-stranded RNA) to apoptosis induction in cancer cell lines was investigated by pharmacological TLR3 inhibition and overexpression. In contrast to controls, Pt-RNA significantly enhanced apoptosis in C. elegans (2-fold) and in the cancer cell lines (2-fold to 4-fold). TLR3 overexpression significantly enhanced the pro-apoptotic effects of Pt-RNA in HepG2 cells. TLR3 inhibition reduced the pro-apoptotic effects of Pt-RNA and cisplatin, but not of paclitaxel (off-target control). Gene expression analysis showed that Pt-RNA (but not RNA) significantly enhanced the mRNA levels of nuclear factor kappa B subunit 2 and interleukin-8 in HepG2 cells, suggesting that Pt-RNA is a damage-associated molecular pattern that additionally causes pro-inflammatory responses. Together, this data suggests that not only DNA but also cellular RNA is a functionally relevant target of cisplatin, leading to pro-apoptotic and immunogenic effects.

The implication of infection with respiratory syncytial virus in pediatric recurrent wheezing and asthma: knowledge expanded post-COVID-19 era

BACKGROUND

Respiratory syncytial virus (RSV) infection has been identified to serve as the primary cause of acute lower respiratory infectious diseases in children under the age of one and a significant risk factor for the emergence and development of pediatric recurrent wheezing and asthma, though the exact mechanism is still unknown.

METHODS AND RESULTS

In this study, we discuss the key routes that lead to recurrent wheezing and bronchial asthma following RSV infection. It is interesting to note that following the coronavirus disease 2019 (COVID-19) epidemic, the prevalence of RSV changes significantly. This presents us with a rare opportunity to better understand the associated mechanism for RSV infection, its effects on the respiratory system, and the immunological response to RSV following the COVID-19 epidemic. To better understand the associated mechanisms in the occurrence and progression of pediatric asthma, we thoroughly described how the RSV infection directly destroys the physical barrier of airway epithelial tissue, promotes inflammatory responses, enhances airway hyper-responsiveness, and ultimately causes the airway remodeling. More critically, extensive discussion was also conducted regarding the potential impact of RSV infection on host pulmonary immune response.

CONCLUSION

In conclusion, this study offers a comprehensive perspective to better understand how the RSV infection interacts in the control of the host's pulmonary immune system, causing recurrent wheezing and the development of asthma, and it sheds fresh light on potential avenues for pharmaceutical therapy in the future.

Spherical nucleic acids: emerging amplifiers for therapeutic nanoplatforms

Gene therapy is a revolutionary treatment approach in the 21st century, offering significant potential for disease prevention and treatment. However, the efficacy of gene delivery is often compromised by the inherent challenges of gene properties and vector-related defects. It is crucial to explore ways to enhance the curative effect of gene drugs and achieve safer, more widespread, and more efficient utilization, which represents a significant challenge in amplification gene therapy advancements. Spherical nucleic acids (SNAs), with their unique physicochemical properties, are considered an innovative solution for scalable gene therapy. This review aims to comprehensively explore the amplifying contributions of SNAs in gene therapy and emphasize the contribution of SNAs to the amplification effect of gene therapy from the aspects of structure, application, and recent clinical translation - an aspect that has been rarely reported or explored thus far. We begin by elucidating the fundamental characteristics and scaling-up properties of SNAs that distinguish them from traditional linear nucleic acids, followed by an analysis of combined therapy treatment strategies, theranostics, and clinical translation amplified by SNAs. We conclude by discussing the challenges of SNAs and provide a prospect on the amplification characteristics. This review seeks to update the current understanding of the use of SNAs in gene therapy amplification and promote further research into their clinical translation and amplification of gene therapy.

SARS-CoV-2 immunity in animal models

The COVID-19 pandemic, which was caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a worldwide health crisis due to its transmissibility. SARS-CoV-2 infection results in severe respiratory illness and can lead to significant complications in affected individuals. These complications encompass symptoms such as coughing, respiratory distress, fever, infectious shock, acute respiratory distress syndrome (ARDS), and even multiple-organ failure. Animal models serve as crucial tools for investigating pathogenic mechanisms, immune responses, immune escape mechanisms, antiviral drug development, and vaccines against SARS-CoV-2. Currently, various animal models for SARS-CoV-2 infection, such as nonhuman primates (NHPs), ferrets, hamsters, and many different mouse models, have been developed. Each model possesses distinctive features and applications. In this review, we elucidate the immune response elicited by SARS-CoV-2 infection in patients and provide an overview of the characteristics of various animal models mainly used for SARS-CoV-2 infection, as well as the corresponding immune responses and applications of these models. A comparative analysis of transcriptomic alterations in the lungs from different animal models revealed that the K18-hACE2 and mouse-adapted virus mouse models exhibited the highest similarity with the deceased COVID-19 patients. Finally, we highlighted the current gaps in related research between animal model studies and clinical investigations, underscoring lingering scientific questions that demand further clarification.

Exploring TLR signaling pathways as promising targets in cervical cancer: The road less traveled

Cervical cancer is the leading cause of cancer-related deaths for women globally. Despite notable advancements in prevention and treatment, the identification of novel therapeutic targets remains crucial for cervical cancer. Toll-like receptors (TLRs) play an essential role in innate immunity as pattern-recognition receptors. There are several types of pathogen-associated molecular patterns (PAMPs), including those present in cervical cancer cells, which have the ability to activate toll-like receptors (TLRs). Recent studies have revealed dysregulated toll-like receptor (TLR) signaling pathways in cervical cancer, leading to the production of inflammatory cytokines and chemokines that can facilitate tumor growth and metastasis. Consequently, TLRs hold significant promise as potential targets for innovative therapeutic agents against cervical cancer. This book chapter explores the role of TLR signaling pathways in cervical cancer, highlighting their potential for targeted therapy while addressing challenges such as tumor heterogeneity and off-target effects. Despite these obstacles, targeting TLR signaling pathways presents a promising approach for the development of novel and effective treatments for cervical cancer.

FAT10 is phosphorylated by IKKβ to inhibit the antiviral type-I interferon response

IFN-I secretion provides a rapid host defense against infection with RNA viruses. Within the host cell, viral RNA triggers the activation of the RIG-I signaling pathway, leading to the production of IFN-I. Because an exaggerated IFN-I response causes severe tissue damage, RIG-I signaling is tightly regulated. One of the factors that control the IFN-I response is the ubiquitin-like modifier FAT10, which is induced by TNF and IFNγ and targets covalently FAT10-linked proteins for proteasomal degradation. However, the mechanism of how FAT10 modulates IFN-I secretion remains to be fully elucidated. Here, we provide strong evidence that FAT10 is phosphorylated by IκB kinase β (IKKβ) upon TNF stimulation and during influenza A virus infection on several serine and threonine residues. FAT10 phosphorylation increases the binding of FAT10 to the TRAF3-deubiquitylase OTUB1 and its FAT10-mediated activation. Consequently, FAT10 phosphorylation results in a low ubiquitylation state of TRAF3, which is unable to maintain interferon regulatory factor 3 phosphorylation and downstream induction of IFN-I. Taken together, we reveal a mechanism of how phosphorylation of FAT10 limits the production of tissue-destructive IFN-I in inflammation.

Mitochondrial Reactive Oxygen Species in TRIF-Dependent Toll-like Receptor 3 Signaling in Bronchial Epithelial Cells against Viral Infection

Toll-like receptor 3 (TLR3) plays an important role in double-stranded RNA recognition and triggers the innate immune response by acting as a key receptor against viral infections. Intracellular reactive oxygen species (ROS) are involved in TLR3-induced inflammatory responses during viral infections; however, their relationship with mitochondrial ROS (mtROS) remains largely unknown. In this study, we show that polyinosinic-polycytidylic acid (poly(I:C)), a mimic of viral RNA, induced TLR3-mediated nuclear factor-kappa B (NF-κB) signaling pathway activation and enhanced mtROS generation, leading to inflammatory cytokine production. TLR3-targeted small interfering RNA (siRNA) and Mito-TEMPO inhibited inflammatory cytokine production in poly(I:C)-treated BEAS-2B cells. Poly(I:C) recruited the TLR3 adaptor molecule Toll/IL-1R domain-containing adaptor, inducing IFN (TRIF) and activated NF-κB signaling. Additionally, TLR3-induced mtROS generation suppression and siRNA-mediated TRIF downregulation attenuated mitochondrial antiviral signaling protein (MAVS) degradation. Our findings provide insights into the TLR3-TRIF signaling pathway and MAVS in viral infections, and suggest TLR3-mtROS as a therapeutic target for the treatment of airway inflammatory and viral infectious diseases.

Analysis of associations between the TLR3 SNPs rs3775291 and rs3775290 and COVID-19 in a cohort of professionals of Belém-PA, Brazil

The objective of this article was to verify associations between the SNPs rs3775291 (Cytosine [C]>Thymine [T]) and rs3775290 (C>T) of TLR3 in professionals from Health Institutions (HI) who worked during the first pandemic wave and COVID-19. A case-control study was carried out with workers from HI in Belém-PA, Brazil, divided into symptomatology groups (Asymptomatic-AS, n=91; and Symptomatic-SI, n=121), and severity groups, classified by Chest CT scan (symptomatic with lung involvement - SCP, n=34; symptomatic without lung involvement - SSP, n=8). Genotyping was performed by Sanger sequencing and statistical analysis was performed using the SPSS program. In the analysis of SNP rs3775291, the homozygous recessive genotype (T/T) was not found and the frequency of the mutant allele (T) was less than 2% in the cohort. For the rs3775290 SNP, the frequency of the mutant allele (T) was greater than 42% in the cohort. No significant associations were found for these SNPs in this cohort (N= 212 individuals). The scientific community and physicians can use these facts to find new methods of managing COVID-19.

Identification and characterization of toll-like receptor genes in silver pomfret (Pampus argenteus) and their involvement in the host immune response to Photobacterium damselae subsp. Damselae and Nocardia seriolae infection

Toll-like receptors (TLRs) are vital pattern recognition receptors that play a critical role in the innate immune response against pathogenic attack. Among the bacteria commonly found in the culture process of silver pomfret, Photobacterium damselae subsp. Damselae (PDD, gram-negative) and Nocardia seriolae (NS, gram-positive), can cause large-scale mortality in this fish species. However, there is currently no research on the role of TLRs in mediating the immune response of silver pomfret to these two bacterial infections. Therefore, in this study, we identified nine PaTLRs family members, including several fish-specific TLRs (TLR14 and TLR21). Phylogenetic analysis revealed that these PaTLRs genes could be classified into five subfamilies, namely TLR1, TLR3, TLR5, TLR7, and TLR11, indicating their evolutionary conservation. To further explore the interactions of TLR genes with immune-related mediators, protein and protein interaction network (PPI) results were generated to explain the association of TLR genes with TNF receptor-associated factor 6 (TRAF6) and other relevant genes in the MyD88-dependent pathway and NF-κb signaling pathway. Subsequently, RT-qPCR was conducted to verify the expression patterns of the nine TLR genes in the gills, skin, kidney, liver, and spleen of healthy fish, with most of the TLRs showing high expression levels in the spleen. Following infection with PDD and NS, these PaTLRs exhibited different expression patterns in the spleen, with PaTLR2, PaTLR3, PaTLR5, PaTLR7, PaTLR9, and PaTLR14 being significantly up-regulated. Furthermore, when spleen cells were treated with bacterial compositions, the majority of PaTLRs expression was up-regulated in response to Lipopolysaccharide (LPS) and lipophosphorylcholic acid (LTA) treatment, except for PaTLR21. Finally, changes in the expression levels of TLR-interacting genes were also observed under the stimulation of bacteria and bacterial compositions. The results of this study provide a preliminary reference for further understanding the mechanism of the innate immune response of the TLR gene family in silver pomfret and offer theoretical support for addressing the disease problems encountered during large-scale fish breeding.

Investigation of the impact of AXL, TLR3, and STAT2 in congenital Zika syndrome through genetic polymorphisms and protein-protein interaction network analyses

INTRODUCTION

Zika virus (ZIKV) is a human teratogen that causes congenital Zika syndrome (CZS). AXL, TLR3, and STAT2 are proteins involved in the ZIKV's entry into cells (AXL) and host's immune response (TLR3 and STAT2). In this study, we evaluated the role of genetic polymorphisms in these three genes as risk factors to CZS, and highlighted which proteins that interact with them could be important for ZIKV infection and teratogenesis.

MATERIALS AND METHODS

We evaluate eighty-eight children exposed to ZIKV during the pregnancy, 40 with CZS and 48 without congenital anomalies. The evaluated polymorphisms in AXL (rs1051008), TLR3 (rs3775291), and STAT2 (rs2066811) were genotyped using TaqMan® Genotyping Assays. A protein-protein interaction network was created in STRING database and analyzed in Cytoscape software.

RESULTS

We did not find any statistical significant association among the polymorphisms and the occurrence of CZS. Through the analyses of the network composed by AXL, TLR3, STAT2 and their interactions targets, we found that EGFR and SRC could be important proteins for the ZIKV infection and its teratogenesis.

CONCLUSION

In summary, our results demonstrated that the evaluated polymorphisms do not seem to represent risk factors for CZS; however, EGFR and SRC appear to be important proteins that should be investigated in future studies.

Laterosporulin25: A probiotically produced, novel defensin-like bacteriocin and its immunogenic properties

Although multiple vaccines have been developed against infectious diseases, the rapid emergence of new pathogens develops an urgent need for novel strategies to combat infectious diseases. Antimicrobial peptides (AMPs) are excellent agents to fight against infectious diseases having unique multiple mechanisms of action against various pathogens. Apart from the direct applications, AMPs can also be developed as subunit vaccines or could be used as a highly immunogenic carrier protein with highly antigenic but non-immunogenic antigens. Here in the present study, we have identified a novel defensin-like bacteriocin, laterosporulin25 (LS25) upon genome mining of Brevibacillus laterosporus DSM25, a probiotic bacterial strain. By using immunoinformatic tools, we have studied the immunogenic and physiochemical properties of LS25. LS25 is characterized as defensin-like bacteriocin, having 51 amino acids and a molecular weight of 5862.7 Da. The modeled tertiary structure of LS25 is docked with TLR3 and TLR4-MD2 complex to confirm the facilitation of induced immune response that is further validated using molecular dynamics simulations and In-silico immune stimulations. Overall, detailed immunoinformatics analysis suggested LS25 as a potential candidate to be used as an adjuvant or carrier protein for subunit vaccine development, however, further in-vitro and in-vivo experiments are essential to validate its potential.

Mycoviruses in Fungi: Carcinogenesis of Fungal Agents May Not Always Be Mycotoxin Related

Certain viruses have been found to induce diverse biological pathways to carcinogenesis, evidenced by the presence of viral gene products in some tumors. Despite the fact that many fungal agents contain mycoviruses, until recently, their possible direct effects on human health, including carcinogenesis and leukemogenesis, had not been explored. In this regard, most studies of fungal agents have rightly concentrated on their mycotoxin formation and effects. Recently, the direct role of yeasts and fungi in the etiology of cancers, including leukemia, have been investigated. While greater attention has been placed on the carcinogenic effects of Candida, the role of filamentous fungi in carcinogenesis has also been explored. Recent findings from studies using the enzyme-linked immunosorbent assay (ELISA) technique indicate that the plasma of patients with acute lymphoblastic leukemia (ALL) uniformly contains antibodies for a certain mycovirus-containing Aspergillus flavus, while controls are negative. The exposure of mononuclear leukocytes from patients with ALL in full remission, and long-term survivors, to the product of this organism was reported to result in the re-development of typical genetics and cell surface phenotypes characteristic of active ALL. Mycoviruses are known to be able to significantly alter the biological characteristics and functions of their host. The possible carcinogenic and leukemogenic role of mycoviruses, with and without their host, needs to be further investigated.

TLR3 and MDA5 Knockout DF-1 cells Enhance Replication of Avian Orthoavulavirus 1

Despite the essential role of innate immunity in defining the outcome of viral infections, the roles played by different components of the avian innate immune system are poorly delineated. Here, we investigated the potential implication of avian toll-like receptor (TLR) 3 (TLR3) and melanoma differentiation-associated (MDA) gene 5 (MDA5) receptors of double-stranded RNA (dsRNA) in induction of the interferon pathway and avian orthoavulavirus 1 (AOAV-1) replication in chicken-origin DF-1 fibroblast cells. TLR3 and MDA5 knockout (KO) DF-1 cells were generated using our avian-specific CRISPR/Cas9 system and stimulated with a synthetic dsRNA ligand polyinosinic:polycytidylic acid [poly(I:C)] or infected with AOAV-1 (previously known as Newcastle disease virus). Poly(I:C) treatment in cell culture media resulted in significant upregulation of interferon (IFN)α, IFNβ, and Mx1 gene expression in wild type (WT) DF-1 cells but not in TLR3-MDA5 double KO cells. Interestingly, poly(I:C) treatment induced rapid cell degeneration in WT and MDA5 KO cells, but not in TLR3 knockout or TRL3-MDA5 double knockout (DKO) cells, directly linking poly(I:C)-induced cell degeneration to TLR3-mediated host response. The double knockout cells supported significantly higher replication of AOAV-1 virus than did the WT cells. However, no correlation between the level of virus replication and type I IFN response was observed. Our study suggests that innate immune response is host- and pathogen specific, and further investigation is needed to understand the relevance of dsRNA receptor-mediated immune responses in viral replication and pathogenesis in avian species.

Pattern-recognition receptors in endometriosis: A narrative review

Endometriosis is closely associated with ectopic focal inflammation and immunosuppressive microenvironment. Multiple types of pattern recognition receptors (PRRs) are present in the innate immune system, which are able to detect pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs) in both intracellular and external environments. However, the exact role of PRRs in endometriosis and the underlying molecular mechanism are unclear. PRRs are necessary for the innate immune system to identify and destroy invasive foreign infectious agents. Mammals mainly have two types of microbial recognition systems. The first one consists of the membrane-bound receptors, such as toll-like receptors (TLRs), which recognize extracellular microorganisms and activate intracellular signals to stimulate immune responses. The second one consists of the intracellular PRRs, including nod-like receptors (NLRs) and antiviral proteins retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated gene 5 (MDA-5) with helix enzyme domain. In this review, we mainly focus on the key role of PRRs in the pathological processes associated with endometriosis. PRRs recognize PAMPs and can distinguish pathogenic microorganisms from self, triggering receptor ligand reaction followed by the stimulation of host immune response. Activated immune response promotes the transmission of microbial infection signals to the cells. As endometriosis is characterized by dysregulated inflammation and immune response, PRRs may potentially be involved in the activation of endometriosis-associated inflammation and immune disorders. Toll-like receptor 2 (TLR2), toll-like receptor 3 (TLR3), toll-like receptor 4 (TLR4), nod-like receptor family caspase activation and recruitment domain (CARD) domain containing 5 (NLRC5), nod-like receptor family pyrin domain containing 3 (NLRP3), and c-type lectin receptors (CLRs) play essential roles in endometriosis development by regulating immune and inflammatory responses. Absent in melanoma 2 (AIM2)-like receptors (ALRs) and retinoic acid-inducible gene I-like receptors (RLRs) may be involved in the activation of endometriosis-associated immune and inflammation disorders. PRRs, especially TLRs, may serve as potential therapeutic targets for alleviating pain in endometriosis patients. PRRs and their ligands interact with the innate immune system to enhance inflammation in the stromal cells during endometriosis. Thus, targeting PRRs and their new synthetic ligands may provide new therapeutic options for treating endometriosis.

Approaches to Evaluating Necroptosis in Virus-Infected Cells

The immune system functions to protect the host from pathogens. To counter host defense mechanisms, pathogens have developed unique strategies to evade detection or restrict host immune responses. Programmed cell death is a major contributor to the multiple host responses that help to eliminate infected cells for obligate intracellular pathogens like viruses. Initiation of programmed cell death pathways during the early stages of viral infections is critical for organismal survival as it restricts the virus from replicating and serves to drive antiviral inflammation immune recruitment through the release of damage-associated molecular patterns (DAMPs) from the dying cell. Necroptosis has been implicated as a critical programmed cell death pathway in a diverse set of diseases and pathological conditions including acute viral infections. This cell death pathway occurs when certain host sensors are triggered leading to the downstream induction of mixed-lineage kinase domain-like protein (MLKL). MLKL induction leads to cytoplasmic membrane disruption and subsequent cellular destruction with the release of DAMPs. As the role of this cell death pathway in human disease becomes apparent, methods identifying necroptosis patterns and outcomes will need to be further developed. Here, we discuss advances in our understanding of how viruses counteract necroptosis, methods to quantify the pathway, its effects on viral pathogenesis, and its impact on cellular signaling.

A Nomogram Based on Preoperative Lab Tests, BMI, ICG-R15, and EHBF for the Prediction of Post-Hepatectomy Liver Failure in Patients with Hepatocellular Carcinoma

Background: Liver cancer is one of the most common malignant tumors, and worldwide, its incidence ranks sixth, and its morality third. Post-hepatectomy liver failure (PHLF) is the leading cause of death in patients who have undergone liver resection. This retrospective study investigated the risk factors for PHLF by predicting and constructing an index to evaluate the risk. This was achieved by combining the lab tests with an indocyanine green (ICG) clearance test. Methods: The study analyzed 1081 hepatocellular carcinoma (HCC) patients who had received liver resection at Sun Yat-sen University Cancer Center between 2005 and 2020. The patients were divided into a PHLF group (n = 113) and a non-PHLF group (n = 968), according to the International Study Group of Liver Surgery (ISGLS) criteria. Receiver operating characteristics (ROC) curves were then used to estimate the optimal cut-off values. Univariate and multivariate logistic regression analyses were performed to identify the independent risk factors. Finally, a nomogram was constructed where the calibration plot, the areas under the ROC curve (AUC), and the decision curve analysis (DCA) showed good predictive ability. Results: Correlation analysis revealed that body mass index (BMI) was positively correlated with ICG-R15 and with effective hepatic blood flow (EHBF). Univariate and multivariate logistics regression analysis revealed that BMI, ICG-R15, international normalized ratio (INR), tumor size, hepatic inflow occlusion (HIO) time, and operation method were independent predictive factors for PHLF. When these factors and EHBF were included in the nomogram, the nomogram showed a good predictive value, with a C-index of 0.773 (95% Confidence Interval [CI]: 0.729-0.818). The INR had the largest ROC areas (AUC INR = 0.661). Among the variables, ICG-R15 (AUC ICG-R15 = 0.604) and EHBF (AUC EHBF = 0.609) also showed good predictive power. Conclusions: The risk of PHLF in HCC patients can be precisely predicted by this model prior to the operation. By integrating EHBF into the model, HCC patients at higher risk for PHLF can be identified more effectively.

An Immunoinformatics Approach to Design a Potent Multi-Epitope Vaccine against Asia-1 Genotype of Crimean-Congo Haemorrhagic Fever Virus Using the Structural Glycoproteins as a Target

Crimean-Congo haemorrhagic fever (CCHF), caused by Crimean-Congo haemorrhagic fever virus (CCHFV), is a disease of worldwide importance (endemic yet not limited to Asia, Middle East, and Africa) and has triggered several outbreaks amounting to a case fatality rate of 10-40% as per the World Health Organization. Genetic diversity and phylogenetic data revealed that the Asia-1 genotype of CCHFV remained dominant in Pakistan, where 688 confirmed cases were reported between the 2012-2022 period. Currently, no approved vaccine is available to tackle the viral infection. Epitope-based vaccine design has gained significant attention in recent years due to its safety, timeliness, and cost efficiency compared to conventional vaccines. In the present study, we employed a robust immunoinformatics-based approach targeting the structural glycoproteins G1 and G2 of CCHFV (Asia-1 genotype) to design a multi-epitope vaccine construct. Five B-cells and six cytotoxic T-lymphocytes (CTL) epitopes were mapped and finalized from G1 and G2 and were fused with suitable linkers (EAAAK, GGGS, AAY, and GPGPG), a PADRE sequence (13 aa), and an adjuvant (50S ribosomal protein L7/L12) to formulate a chimeric vaccine construct. The selected CTL epitopes showed high affinity and stable binding with the binding groove of common human HLA class I molecules (HLA-A*02:01 and HLA-B*44:02) and mouse major histocompatibility complex class I molecules. The chimeric vaccine was predicted to be an antigenic, non-allergenic, and soluble molecule with a suitable physicochemical profile. Molecular docking and molecular dynamics simulation indicated a stable and energetically favourable interaction between the constructed antigen and Toll-like receptors (TLR2, TLR3, and TLR4). Our results demonstrated that innate, adaptive, and humoral immune responses could be elicited upon administration of such a potent muti-epitope vaccine construct. These results could be helpful for an experimental vaccinologist to develop an effective vaccine against the Asia-1 genotype of CCHFV.

Roles of RIPK3 in necroptosis, cell signaling, and disease

Receptor-interacting protein kinase-3 (RIPK3, or RIP3) is an essential protein in the "programmed" and "regulated" cell death pathway called necroptosis. Necroptosis is activated by the death receptor ligands and pattern recognition receptors of the innate immune system, and the findings of many reports have suggested that necroptosis is highly significant in health and human disease. This significance is largely because necroptosis is distinguished from other modes of cell death, especially apoptosis, in that it is highly proinflammatory given that cell membrane integrity is lost, triggering the activation of the immune system and inflammation. Here, we discuss the roles of RIPK3 in cell signaling, along with its role in necroptosis and various pathways that trigger RIPK3 activation and cell death. Lastly, we consider pathological situations in which RIPK3/necroptosis may play a role.

Clinical Management of Herpes Simplex Virus Keratitis

Herpes simplex virus (HSV) keratitis is one of the leading causes of blindness worldwide. Additionally, up to 90% of the population in some countries is seropositive for HSV. HSV can cause a wide spectrum of ocular disease ranging from blepharitis to retinitis. Although the initial clinical expressions of HSV-1 and HSV-2 are similar, HSV-2 has been reported more frequently in association with recurrent HSV disease. Besides irreversible vision loss from keratitis, HSV also causes encephalitis and genital forms of the disease. Despite these statistics, there remains no vaccine against HSV. Current treatment therapies for related ocular diseases include the use of oral and topical antivirals and topical corticosteroids. While effective in many cases, they fail to address the latency and elimination of the virus, making it ineffective in addressing recurrences, a factor which increases the risk of vision loss. As such, there is a need for continued research of other potential therapeutic targets. This review utilized several published articles regarding the manifestations of HSV keratitis, antiviral immune responses to HSV infection, and clinical management of HSV keratitis. This review will summarize the current knowledge on the host–virus interaction in HSV infections, as well as highlighting the current and potential antiviral therapeutics.

Toll-Like Receptor 3 (TLR3) Is Engaged in the Intracellular Survival of the Protozoan Parasite Leishmania (Leishmania) amazonensis

The protozoan parasite Leishmania (L.) amazonensis infects and replicates inside host macrophages due to subversion of the innate host cell response. In the present study, we demonstrate that TLR3 is required for the intracellular growth of L. (L.) amazonensis. We observed restricted intracellular infection of TLR3-/- mouse macrophages, reduced levels of IFN1β and IL-10, and increased levels of IL-12 upon L. (L.) amazonensis infection, compared with their wild-type counterparts. Accordingly, in vivo infection of TLR3-/- mice with L. (L.) amazonensis displayed a significant reduction in lesion size. Leishmania (L.) amazonensis infection induced TLR3 proteolytic cleavage, which is a process required for TLR3 signaling. The chemical inhibition of TLR3 cleavage or infection by CPB-deficient mutant L. (L.) mexicana resulted in reduced parasite load and restricted the expression of IFN1β and IL-10. Furthermore, we show that the dsRNA sensor molecule PKR (dsRNA-activated protein kinase) cooperates with TLR3 signaling to potentiate the expression of IL-10 and IFN1β and parasite survival. Altogether, our results show that TLR3 signaling is engaged during L. (L.) amazonensis infection and this component of innate immunity modulates the host cell response.

TLR3 polymorphisms in HIV infected individuals naïve to ART

BACKGROUND

TLR3 polymorphisms affect the risk of HIV infection and modify the disease course. Consequently, we analyzed the association of TLR3 polymorphism (rs5743312, rs3775296, and rs3775291) with susceptilbity to HIV-1 acquisition and disease progression.

METHOD

This is a cross-sectional study. Genotyping of TLR3 polymorphisms were completed by the utilization of the PCR-RFLP technique in 153 HIV naive subjects and 158 healthy controls.

RESULT

A haplotype is a physical grouping of genomic variants that tend to be inherited together. The TCC haplotype was increased in HIV infected individuals compared with healthy controls (0.05% versus 0.03%). TLR3 rs3775291CT genotype was associated to the early stage of HIV infection (OR=2.19, P=0.04), with a higher occurrence in advance stage of HIV infection when contrasted with healthy controls (41.2% versus 32.3%). TLR3 rs3775296 CA genotype was likely to be associated with intermediate stage of HIV infection (19.5% versus 31.6%, OR=0.42, P=0.06). TLR3 rs5743312TT genotype was used to be greater prevalence in advanced stage of HIV infection compared with healthy controls (2.9% versus 1.9%). TLR3 rs3775296CA genotype was less prevalent in HIV subjects devouring tobacco when contrasted with non-users (9.1% versus 34.9%, OR=0.25, P=0.09). TLR3 rs3775296AA and rs3775291CT and TT genotypes have been overrepresented in HIV subjects using alcohol when contrasted with non-users (5.6% versus 1.1%, OR=1.83, P=0.67; 50.0% versus 42.2%, OR=1.84, P=0.31; 5.6% versus 3.3%, OR=2.70, P=0.50). In multivariate examination, rs5743312TT genotype showed a greater risk for HIV infection (OR=1.86, P=0.50).

CONCLUSION

TLR3 rs3775291 C/T polymorphism may assist the risk of disease progression in alcohol consumers. TLR3 rs3775291 CT genotype may enhance the disease progression whereas the TLR3 rs3775296 CA genotype may protect for disease progression.

Exploring whole proteome to contrive multi-epitope-based vaccine for NeoCoV: An immunoinformtics and in-silico approach

Neo-Coronavirus (NeoCoV) is a novel Betacoronavirus (β-CoVs or Beta-CoVs) discovered in bat specimens in South Africa during 2011. The viral sequence is highly similar to Middle East Respiratory Syndrome, particularly that of structural proteins. Thus, scientists have emphasized the threat posed by NeoCoV associated with human angiotensin-converting enzyme 2 (ACE2) usage, which could lead to a high death rate and faster transmission rate in humans. The development of a NeoCoV vaccine could provide a promising option for the future control of the virus in case of human infection. In silico predictions can decrease the number of experiments required, making the immunoinformatics approaches cost-effective and convenient. Herein, with the aid of immunoinformatics and reverse vaccinology, we aimed to formulate a multi-epitope vaccine that may be used to prevent and treat NeoCoV infection. Based on the NeoCoV proteins, B-cell, cytotoxic T lymphocyte (CTL), and helper T lymphocyte (HTL) epitopes were shortlisted. Four vaccines (Neo-1-4) were devised by fusing shortlisted epitopes with appropriate adjuvants and linkers. The secondary and three-dimensional structures of final vaccines were then predicted. The binding interactions of these potential vaccines with toll-like immune receptors (TLR-2, TLR-3, and TLR-4) and major histocompatibility complex molecules (MHC-I and II) reveal that they properly fit into the receptors' binding domains. Besides, Neo-1 and Neo-4 vaccines exhibited better docking energies of -101.08 kcal/mol and -114.47 kcal/mol, respectively, with TLR-3 as compared to other vaccine constructs. The constructed vaccines are highly antigenic, non-allergenic, soluble, non-toxic, and topologically assessable with good physiochemical characteristics. Codon optimization and in-silico cloning confirmed efficient expression of the designed vaccines in Escherichia coli strain K12. In-silico immune simulation indicated that Neo-1 and Neo-4 vaccines could induce a strong immune response against NeoCoV. Lastly, the binding stability and strong binding affinity of Neo-1 and Neo-4 with TLR-3 receptor were validated using molecular dynamics simulations and free energy calculations (Molecular Mechanics/Generalized Born Surface Area method). The final vaccines require experimental validation to establish their safety and effectiveness in preventing NeoCoV infections.

Design of a Multiepitope Vaccine against Chicken Anemia Virus Disease

Chicken anemia virus (CAV) causes severe clinical and sub-clinical infection in poultry globally and thus leads to economic losses. The drawbacks of the commercially available vaccines against CAV disease signal the need for a novel, safe, and effective vaccine design. In this study, a multiepitope vaccine (MEV) consisting of T-cell and B-cell epitopes from CAV viral proteins (VP1 and VP2) was computationally constructed with the help of linkers and adjuvant. The 3D model of the MEV construct was refined and validated by different online bioinformatics tools. Molecular docking showed stable interaction of the MEV construct with TLR3, and this was confirmed by Molecular Dynamics Simulation. Codon optimization and in silico cloning of the vaccine in pET-28a (+) vector also showed its potential expression in the E. coli K12 system. The immune simulation also indicated the ability of this vaccine to induce an effective immune response against this virus. Although the vaccine in this study was computationally constructed and still requires further in vivo study to confirm its effectiveness, this study marks a very important step towards designing a potential vaccine against CAV disease.

Pathogenesis and Manifestations of Zika Virus-Associated Ocular Diseases

Zika virus (ZIKV) is mosquito-borne flavivirus that caused a significant public health concern in French Polynesia and South America. The two major complications that gained the most media attention during the ZIKV outbreak were Guillain-Barré syndrome (GBS) and microcephaly in newborn infants. The two modes of ZIKV transmission are the vector-borne and non-vector borne modes of transmission. Aedes aegypti and Aedes albopictus are the most important vectors of ZIKV. ZIKV binds to surface receptors on permissive cells that support infection and replication, such as neural progenitor cells, dendritic cells, dermal fibroblasts, retinal pigment epithelial cells, endothelial cells, macrophages, epidermal keratinocytes, and trophoblasts to cause infection. The innate immune response to ZIKV infection is mediated by interferons and natural killer cells, whereas the adaptive immune response is mediated by CD8⁺T cells, Th1 cells, and neutralizing antibodies. The non-structural proteins of ZIKV, such as non-structural protein 5, are involved in the evasion of the host's immune defense mechanisms. Ocular manifestations of ZIKV arise from the virus' ability to cross both the blood-brain barrier and blood-retinal barrier, as well as the blood-aqueous barrier. Most notably, this results in the development of GBS, a rare neurological complication in acute ZIKV infection. This can yield ocular symptoms and signs. Additionally, infants to whom ZIKV is transmitted congenitally develop congenital Zika syndrome (CZS). The ocular manifestations are widely variable, and include nonpurulent conjunctivitis, anterior uveitis, keratitis, trabeculitis, congenital glaucoma, microphthalmia, hypoplastic optic disc, and optic nerve pallor. There are currently no FDA approved therapeutic agents for treating ZIKV infections and, as such, a meticulous ocular examination is an important aspect of the diagnosis. This review utilized several published articles regarding the ocular findings of ZIKV, antiviral immune responses to ZIKV infection, and the pathogenesis of ocular manifestations in individuals with ZIKV infection. This review summarizes the current knowledge on the viral immunology of ZIKV, interactions between ZIKV and the host's immune defense mechanism, pathological mechanisms, as well as anterior and posterior segment findings associated with ZIKV infection.

The RHIM of the Immune Adaptor Protein TRIF Forms Hybrid Amyloids with Other Necroptosis-Associated Proteins

TIR-domain-containing adapter-inducing interferon-β (TRIF) is an innate immune protein that serves as an adaptor for multiple cellular signalling outcomes in the context of infection. TRIF is activated via ligation of Toll-like receptors 3 and 4. One outcome of TRIF-directed signalling is the activation of the programmed cell death pathway necroptosis, which is governed by interactions between proteins that contain a RIP Homotypic Interaction Motif (RHIM). TRIF contains a RHIM sequence and can interact with receptor interacting protein kinases 1 (RIPK1) and 3 (RIPK3) to initiate necroptosis. Here, we demonstrate that the RHIM of TRIF is amyloidogenic and supports the formation of homomeric TRIF-containing fibrils. We show that the core tetrad sequence within the RHIM governs the supramolecular organisation of TRIF amyloid assemblies, although the stable amyloid core of TRIF amyloid fibrils comprises a much larger region than the conserved RHIM only. We provide evidence that RHIMs of TRIF, RIPK1 and RIPK3 interact directly to form heteromeric structures and that these TRIF-containing hetero-assemblies display altered and emergent properties that likely underlie necroptosis signalling in response to Toll-like receptor activation.

Association of toll-like receptors single nucleotide polymorphisms with HBV and HCV infection: research status

Background

Hepatitis B virus (HBV) and hepatitis C virus (HCV) infections have become increasingly severe worldwide and are a threat to public health. There have been a number of studies conducted recently on the relationship of single nucleotide polymorphisms (SNPs) to innate immune receptor genes such as toll-like receptors (TLRs). Some literature suggests that SNPs of TLRs are associated with HBV and HCV infection. We summarized the role of TLRs gene polymorphisms associated with HBV and HCV infections and explored their possible mechanisms of action.

Methodology

PubMed and Web of Science were used to perform the literature review. Related articles and references were identified and used to analyze the role of TLRs gene polymorphism in HBV and HCV infection.

Results

TLRs gene polymorphisms may have beneficial or detrimental effects in HBV and HCV infection, and some SNPs can affect disease progression or prognosis. They affect the disease state by altering gene expression or protein synthesis; however, the mechanism of action is not clearly understood.

Conclusions

Single nucleotide polymorphisms of TLRs play a role in HBV and HCV infection, but the mechanism of action still needs to be explored in future studies.

TLR Signals in Epithelial Cells in the Nasal Cavity and Paranasal Sinuses

The respiratory tract is constantly at risk of invasion by microorganisms such as bacteria, viruses, and fungi. In particular, the mucosal epithelium of the nasal cavity and paranasal sinuses is at the very forefront of the battles between the host and the invading pathogens. Recent studies have revealed that the epithelium not only constitutes a physical barrier but also takes an essential role in the activation of the immune system. One of the mechanisms equipped in the epithelium to fight against microorganisms is the Toll-like receptor (TLR) response. TLRs recognize common structural components of microorganisms and activate the innate immune system, resulting in the production of a plethora of cytokines and chemokines in the response against microbes. As the epithelia-derived cytokines are deeply involved in the pathogenesis of inflammatory conditions in the nasal cavity and paranasal sinuses, such as chronic rhinosinusitis (CRS) and allergic rhinitis (AR), the molecules involved in the TLR response may be utilized as therapeutic targets for these diseases. There are several differences in the TLR response between nasal and bronchial epithelial cells, and knowledge of the TLR signals in the upper airway is sparse compared to that in the lower airway. In this review, we provide recent evidence on TLR signaling in the upper airway, focusing on the expression, regulation, and responsiveness of TLRs in human nasal epithelial cells (HNECs). We also discuss how TLRs in the epithelium are involved in the pathogenesis of, and possible therapeutic targeting, for CRS and AR.

Regulation of IRF3 activation in Human Antiviral Signalling Pathways

The interferon regulatory factor (IRF) family of transcription factors play a vital role in the human innate antiviral immune responses with production of interferons (IFNs) as a hallmark outcome of activation. In recent years, IRF3 has been considered a principal early regulator of type I IFNs (TI-IFNs) directly downstream of intracellular virus sensing. Despite decades of research on IRF-activating pathways, many questions remain on the regulation of IRF3 activation. The kinases IκB kinase epsilon (IKKε) and TANK-binding kinase-1 (TBK1) and the scaffold proteins TRAF family member-associated NF-kappa-B activator (TANK), NF-kappa-B-activating kinase-associated protein 1 (NAP1) and TANK-binding kinase 1-binding protein 1 (TBKBP1)/similar to NAP1 TBK1 adaptor (SINTBAD) are believed to be core components of an IRF3-activation complex yet their contextual involvement and complex composition are still unclear. This review will give an overview of antiviral signaling pathways leading to the activation of IRF3 and discuss recent developments in our understanding of its proximal regulation.

Toll-Like Receptor 3 Is Critical to the Pancreatic Islet Milieu That Is Required for Coxsackievirus B4-Induced Type 1 Diabetes in Female Nonobese Diabetic Mice

OBJECTIVE

Genetic and environmental influences play a role as triggers of type 1 diabetes mellitus (T1DM). Female nonobese diabetic (NOD) mice are useful for studying T1DM as they spontaneously develop T1DM, which can be accelerated by some viruses. Toll-like receptor 3 (TLR3) is believed to play a critical role in viral-induced T1DM and β-cell destruction, because female Tlr3 knockout (Tlr3-/-) NOD mice are protected from Coxsackievirus B4 (CVB4)-induced acceleration of T1DM. However, the exact role(s) TLR3 plays in the pathogenesis of CVB4-induced T1DM remain unknown.

METHODS

This longitudinal study used immunostaining, laser capture microdissection, and reverse transcription real-time polymerase chain reaction of islets from female uninfected and CVB4-infected Tlr3+/+ and Tlr3-/- NOD mice.

RESULTS

Islets isolated from female Tlr3+/+ NOD mice 4 to 8 weeks of age had higher amounts of insulitis, Cxcl10, Il1b, Tnfa, and Tgfb1 expression compared with Tlr3-/- NOD mice. After CVB4 infection, Tlr3+/+ NOD mice had higher amounts of insulitis and T-cell infiltration at 3 days after infection compared with Tlr3-/- CVB4-infected NOD mice.

CONCLUSIONS

Toll-like receptor 3 is necessary for establishment of a pancreatic islet inflammatory microenvironment by increasing insulitis and cytokine expression that facilitates CVB4-induced T1DM in female NOD mice.

RIGI, TLR7, and TLR3 Genes Were Predicted to Have Immune Response Against Avian Influenza in Indigenous Ducks

Avian influenza is a disease with every possibility to evolve as a human-to-human pandemic arising out of frequent mutations and genetic reassortment or recombination of avian influenza (AI) virus. The greatest concern is that till date, no satisfactory medicine or vaccines are available, leading to massive culling of poultry birds, causing huge economic loss and ban on export of chicken products, which emphasizes the need to develop an alternative strategy for control of AI. In the current study, we attempt to explore the molecular mechanism of innate immune potential of ducks against avian influenza. In the present study, we have characterized immune response molecules such as duck TLR3, TLR7, and RIGI that are predicted to have potent antiviral activities against the identified strain of avian influenza through in silico studies (molecular docking) followed by experimental validation with differential mRNA expression analysis. Future exploitation may include immunomodulation with the recombinant protein, and transgenic or gene-edited chicken resistant to bird flu.

Adoptive cell therapy with tumor-specific Th9 cells induces viral mimicry to eliminate antigen-loss-variant tumor cells

Resistance can occur in patients receiving adoptive cell therapy (ACT) due to antigen-loss-variant (ALV) cancer cell outgrowth. Here we demonstrate that murine and human T helper (Th) 9 cells, but not Th1/Tc1 or Th17 cells, expressing tumor-specific T cell receptors (TCRs) or chimeric antigen receptors (CARs), eradicate advanced tumors that contain ALVs. This unprecedented antitumor capacity of Th9 cells is attributed to both enhanced direct tumor cell killing and bystander antitumor effects promoted by intratumor release of interferon (IFN) α/β. Mechanistically, tumor-specific Th9 cells increase the intratumor accumulation of extracellular ATP (eATP; released from dying tumor cells), because of a unique feature of Th9 cells that lack the expression of ATP degrading ectoenzyme cluster of differentiation (CD) 39. Intratumor enrichment of eATP promotes the monocyte infiltration and stimulates their production of IFNα/β by inducing eATP-endogenous retrovirus-Toll-like receptor 3 (TLR3)/mitochondrial antiviral signaling (MAVS) pathway activation. These results identify tumor-specific Th9 cells as a unique T cell subset endowed with the unprecedented capacity to eliminate ALVs for curative responses.

Immunostimulant Bathing Influences the Expression of Immune- and Metabolic-Related Genes in Atlantic Salmon Alevins

Disease resistance of fish larvae may be improved by bath treatment in water containing immunostimulants. Pattern recognition receptors, such as TLR3, TLR7, and MDA5, work as an "early warning" to induce intracellular signaling and facilitate an antiviral response. A single bath of newly hatched larvae, with Astragalus, upregulated the expression of IFNα, IFNc, ISG15, MDA5, PKR, STAT1, TLR3, and TLR7 immune genes, on day 4 post treatment. Similar patterns were observed for Hyaluronic acid and Poly I:C. Increased expression was observed for ISG15, MDA5, MX, STAT1, TLR3, TLR7, and RSAD2, on day 9 for Imiquimod. Metabolic gene expression was stimulated on day 1 after immunostimulant bath in ULK1, MYC, SLC2A1, HIF1A, MTOR, and SIX1, in Astragalus, Hyaluronic acid, and Imiquimod. Expression of NOS2 in Poly I:C was an average fourfold above that of control at the same timepoint. Throughout the remaining sampling days (2, 4, 9, 16, 32, and 45 days post immunostimulant bath), NOS2 and IL1B were consistently overexpressed. In conclusion, the immunostimulants induced antiviral gene responses, indicating that a single bath at an early life stage could enable a more robust antiviral defense in fish. Additionally, it was demonstrated, based on gene expression data, that cell metabolism was perturbed, where several metabolic genes were co-regulated with innate antiviral genes.

Giardia duodenalis Induces Proinflammatory Cytokine Production in Mouse Macrophages via TLR9-Mediated p38 and ERK Signaling Pathways

Giardia duodenalis, also known as Giardia lamblia or Giardia intestinalis, is an important opportunistic, pathogenic, zoonotic, protozoan parasite that infects the small intestines of humans and animals, causing giardiasis. Several studies have demonstrated that innate immunity-associated Toll-like receptors (TLRs) are critical for the elimination of G. duodenalis; however, whether TLR9 has a role in innate immune responses against Giardia infection remains unknown. In the present study, various methods, including reverse transcriptase–quantitative polymerase chain reaction, Western blot, enzyme-linked immunosorbent assay, immunofluorescence, inhibitor assays, and small-interfering RNA interference, were utilized to probe the role of TLR9 in mouse macrophage-mediated defenses against G. lamblia virus (GLV)–free or GLV-containing Giardia trophozoites. The results revealed that in G. duodenalis–stimulated mouse macrophages, the secretion of proinflammatory cytokines, including interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), and IL-12 p40, was enhanced, concomitant with the significant activation of TLR9, whereas silencing TLR9 attenuated the host inflammatory response. Notably, the presence of GLV exacerbated the secretion of host proinflammatory cytokines. Moreover, G. duodenalis stimulation activated multiple signaling pathways, including the nuclear factor κB p65 (NF-κB p65), p38, ERK, and AKT pathways, the latter three in a TLR9-dependent manner. Additionally, inhibiting the p38 or ERK pathway downregulated the G. duodenalis–induced inflammatory response, whereas AKT inhibition aggravated this process. Taken together, these results indicated that G. duodenalis may induce the secretion of proinflammatory cytokines by activating the p38 and ERK signaling pathways in a TLR9-dependent manner in mouse macrophages. Our in vitro findings on the mechanism underlying the TLR9-mediated host inflammatory response may help establish the foundation for an in-depth investigation of the role of TLR9 in the pathogenicity of G. duodenalis.

Development of a Novel Multi-Epitope Vaccine Against Crimean-Congo Hemorrhagic Fever Virus: An Integrated Reverse Vaccinology, Vaccine Informatics and Biophysics Approach

Crimean-Congo hemorrhagic fever (CCHF) is a highly severe and virulent viral disease of zoonotic origin, caused by a tick-born CCHF virus (CCHFV). The virus is endemic in many countries and has a mortality rate between 10% and 40%. As there is no licensed vaccine or therapeutic options available to treat CCHF, the present study was designed to focus on application of modern computational approaches to propose a multi-epitope vaccine (MEV) expressing antigenic determinants prioritized from the CCHFV genome. Integrated computational analyses revealed the presence of 9 immunodominant epitopes from Nucleoprotein (N), RNA dependent RNA polymerase (RdRp), Glycoprotein N (Gn/G2), and Glycoprotein C (Gc/G1). Together these epitopes were observed to cover 99.74% of the world populations. The epitopes demonstrated excellent binding affinity for the B- and T-cell reference set of alleles, the high antigenic potential, non-allergenic nature, excellent solubility, zero percent toxicity and interferon-gamma induction potential. The epitopes were engineered into an MEV through suitable linkers and adjuvating with an appropriate adjuvant molecule. The recombinant vaccine sequence revealed all favorable physicochemical properties allowing the ease of experimental analysis in vivo and in vitro. The vaccine 3D structure was established ab initio. Furthermore, the vaccine displayed excellent binding affinity for critical innate immune receptors: TLR2 (-14.33 kcal/mol) and TLR3 (-6.95 kcal/mol). Vaccine binding with these receptors was dynamically analyzed in terms of complex stability and interaction energetics. Finally, we speculate the vaccine sequence reported here has excellent potential to evoke protective and specific immune responses subject to evaluation of downstream experimental analysis.

In silico design of a multi-epitope peptide construct as a potential vaccine candidate for Influenza A based on neuraminidase protein

Designing an effective vaccine against different subtypes of Influenza A virus is a critical issue in the field of medical biotechnology. At the current study, a novel potential multi-epitope vaccine candidate based on the neuraminidase proteins for seven subtypes of Influenza virus was designed, using the in silico approach. Potential linear B-cell and T-cell binding epitopes from each neuraminidase protein (N1, N2, N3, N4, N6, N7, N8) were predicted by in silico tools of epitope prediction. The selected epitopes were joined by three different linkers, and physicochemical properties, toxicity, and allergenecity were investigated. The final multi-epitope construct was modeled using GalaxyWEB server, and the molecular interactions with immune receptors were investigated and the immune response simulation assay was performed. A multi-epitope construct with GPGPGPG linker with the lowest allergenicity and highest stability was selected. The molecular docking assay indicated the interactions with immune system receptors, including HLA1, HLA2, and TLR-3. Immune response simulation detected both humoral and cellular response, including the elevated count of B-cells, T-cell, and Nk-cells.

Evaluation of Toll-like receptor 3 (TLR3) signaling pathway genes and its genetic polymorphisms in ectopic and eutopic endometrium of women with endometriosis

OBJECTIVE

Toll-like receptors (TLRs, as members of the innate immune system) are expressed in the human endometrium and their aberrant regulation and expression are involved in the pathogenesis of endometrial diseases. This study is aimed at evaluation of TLR3 signaling pathway genes and its genetic changes in endometriosis patients.

MATERIALS AND METHODS

Blood samples were collected from 83 endometriosis patients and 93 healthy fertile women and PCR was performed in blood-derived DNA for detection of SNP of TLR3. Also, ectopic (EC) and eutopic (EU) endometrial biopsies were obtained from endometriosis patients (n = 20), as well as endometrium from healthy women (n = 16, CE). Q-PCR was performed for determination of mRNA expression level of TLR3 signaling pathway genes (TLR3, TICAM, NF-kB1A, CXCL10, IRF3, IFN-B1, IL-6 and IL-8). Also, serum protein levels of TLR3, IFN-β, IL-6 and IL-8 were determined using ELISA.

RESULTS

The mRNA expression levels of TLR3, NF-kB1A, IFN-B1, IRF3, TICAM1, IL-6 and IL-8 were significantly higher in EU compared to ectopic ones and also compared to CE. SNPs frequency (rs3775291 and rs3775290) was not significantly different between patients and controls. Serum protein levels of TLR3, IFN-β, IL-6 and IL-8 were significantly increased in endometriosis patients.

CONCLUSION

Significant changes were observed in the expression of IL-6 and IL-8 cytokines and other genes in TLR3 cascade in diseased EU, demonstrating that EU similarly to EC is in an intensive inflammatory state. These fundamental alterations in the concept of immune response in EU may lead to its activation, escapes from apoptosis, and displaced implantation of the endometrium.

Inhibition of innate immune response ameliorates Zika virus-induced neurogenesis deficit in human neural stem cells

Global Zika virus (ZIKV) outbreaks and their strong link to microcephaly have raised major public health concerns. ZIKV has been reported to affect the innate immune responses in neural stem/progenitor cells (NS/PCs). However, it is unclear how these immune factors affect neurogenesis. In this study, we used Asian-American lineage ZIKV strain PRVABC59 to infect primary human NS/PCs originally derived from fetal brains. We found that ZIKV overactivated key molecules in the innate immune pathways to impair neurogenesis in a cell stage-dependent manner. Inhibiting the overactivated innate immune responses ameliorated ZIKV-induced neurogenesis reduction. This study thus suggests that orchestrating the host innate immune responses in NS/PCs after ZIKV infection could be promising therapeutic approach to attenuate ZIKV-associated neuropathology.

Cytokine Signature Induced by SARS-CoV-2 Spike Protein in a Mouse Model

Although COVID-19 has become a major challenge to global health, there are currently no efficacious agents for effective treatment. Cytokine storm syndrome (CSS) can lead to acute respiratory distress syndrome (ARDS), which contributes to most COVID-19 mortalities. Research points to interleukin 6 (IL-6) as a crucial signature of the cytokine storm, and the clinical use of the IL-6 inhibitor tocilizumab shows potential for treatment of COVID-19 patient. In this study, we challenged wild-type and adenovirus-5/human angiotensin-converting enzyme 2-expressing BALB/c mice with a combination of polyinosinic-polycytidylic acid and recombinant SARS-CoV-2 spike-extracellular domain protein. High levels of TNF-α and nearly 100 times increased IL-6 were detected at 6 h, but disappeared by 24 h in bronchoalveolar lavage fluid (BALF) following immunostimulant challenge. Lung injury observed by histopathologic changes and magnetic resonance imaging at 24 h indicated that increased TNF-α and IL-6 may initiate CSS in the lung, resulting in the continual production of inflammatory cytokines. We hypothesize that TNF-α and IL-6 may contribute to the occurrence of CSS in COVID-19. We also investigated multiple monoclonal antibodies (mAbs) and inhibitors for neutralizing the pro-inflammatory phenotype of COVID-19: mAbs against IL-1α, IL-6, TNF-α, and granulocyte-macrophage colony-stimulating factor (GM-CSF), and inhibitors of p38 and JAK partially relieved CSS; mAbs against IL-6, TNF-α, and GM-CSF, and inhibitors of p38, extracellular signal-regulated kinase, and myeloperoxidase somewhat reduced neutrophilic alveolitis in the lung. This novel murine model opens a biologically safe, time-saving avenue for clarifying the mechanism of CSS/ARDS in COVID-19 and developing new therapeutic drugs.

Immunoinformatics prediction of overlapping CD8+ T-cell, IFN-γ and IL-4 inducer CD4+ T-cell and linear B-cell epitopes based vaccines against COVID-19 (SARS-CoV-2)

At the beginning of the year 2020, the world was struck with a global pandemic virus referred to as SARS-CoV-2 (COVID-19) which has left hundreds of thousands of people dead. To control this virus, vaccine design becomes imperative. In this study, potential epitopes-based vaccine candidates were explored. Six hundred (600) genomes of SARS-CoV-2 were retrieved from the viPR database to generate CD8⁺ T-cell, CD4+ T-cell and linear B-cell epitopes which were screened for antigenicity, immunogenicity and non-allergenicity. The results of this study provide 19 promising candidate CD8⁺ T-cell epitopes that strongly overlap with 8 promising B-cells epitopes. Another 19 CD4⁺ T-cell epitopes were also identified that can induce IFN-γ and IL-4 cytokines. The most conserved MHC-I and MHC-II for both CD8⁺ and CD4⁺ T-cell epitopes are HLA-A*02:06 and HLA-DRB1*01:01 respectively. These epitopes also bound to Toll-like receptor 3 (TLR3). The population coverage of the conserved Major Histocompatibility Complex Human Leukocyte Antigen (HLA) for both CD8⁺ T-cell and CD4⁺ T-cell ranged from 65.6% to 100%. The detailed analysis of the potential epitope-based vaccine and their mapping to the complete COVID-19 genome reveals that they are predominantly found in the location of the surface (S) and membrane (M) glycoproteins suggesting the potential involvement of these structural proteins in the immunogenic response and antigenicity of the virus. Since the majority of the potential epitopes are located on M protein, the design of multi-epitope vaccine with the structural protein is highly promising though the whole M protein could also serve as a viable epitope for the development of an attenuated vaccine. Our findings provide a baseline for the experimental design of a suitable vaccine against SARS-CoV-2.

Dynamic data-driven meta-analysis for prioritisation of host genes implicated in COVID-19

The increasing body of literature describing the role of host factors in COVID-19 pathogenesis demonstrates the need to combine diverse, multi-omic data to evaluate and substantiate the most robust evidence and inform development of therapies. Here we present a dynamic ranking of host genes implicated in human betacoronavirus infection (SARS-CoV-2, SARS-CoV, MERS-CoV, seasonal coronaviruses). We conducted an extensive systematic review of experiments identifying potential host factors. Gene lists from diverse sources were integrated using Meta-Analysis by Information Content (MAIC). This previously described algorithm uses data-driven gene list weightings to produce a comprehensive ranked list of implicated host genes. From 32 datasets, the top ranked gene was PPIA, encoding cyclophilin A, a druggable target using cyclosporine. Other highly-ranked genes included proposed prognostic factors (CXCL10, CD4, CD3E) and investigational therapeutic targets (IL1A) for COVID-19. Gene rankings also inform the interpretation of COVID-19 GWAS results, implicating FYCO1 over other nearby genes in a disease-associated locus on chromosome 3. Researchers can search and review the gene rankings and the contribution of different experimental methods to gene rank at https://baillielab.net/maic/covid19 . As new data are published we will regularly update the list of genes as a resource to inform and prioritise future studies.

Toll-like receptor-mediated innate immunity against herpesviridae infection: a current perspective on viral infection signaling pathways

Background

In the past decades, researchers have demonstrated the critical role of Toll-like receptors (TLRs) in the innate immune system. They recognize viral components and trigger immune signal cascades to subsequently promote the activation of the immune system.

Main body

Herpesviridae family members trigger TLRs to elicit cytokines in the process of infection to activate antiviral innate immune responses in host cells. This review aims to clarify the role of TLRs in the innate immunity defense against herpesviridae, and systematically describes the processes of TLR actions and herpesviridae recognition as well as the signal transduction pathways involved.

Conclusions

Future studies of the interactions between TLRs and herpesviridae infections, especially the subsequent signaling pathways, will not only contribute to the planning of effective antiviral therapies but also provide new molecular targets for the development of antiviral drugs.

Plasmodium yoelii Uses a TLR3-Dependent Pathway to Achieve Mammalian Host Parasitism

Malaria is associated with complicated immunopathogenesis. In this study, we provide evidence for an unexpected role of TLR3 in promoting the establishment of Plasmodium yoelii infection through delayed clearance of parasitemia in wild type C57BL/6jRj (B6) compared with TLR3 knockout mice. In this study, we confirmed an increased expression of Tlr3, Trif, Tbk1, and Irf7/Irf3 in the liver 42 h postinfection and the initiation of an early burst of proinflammatory response such as Ifng, NF-kB, and Tnfa in B6 mice that may promote parasite fitness. Interestingly, in the absence of TLR3, we showed the involvement of high IFN-γ and lower type I IFN response in the early clearance of parasitemia. In parallel, we observed an increase in splenic NK and NKT cells expressing TLR3 in infected B6 mice, suggesting a role for TLR sensing in the innate immune response. Finally, we find evidence that the increase in the frequency of CD19⁺TLR3⁺ B cells along with reduced levels of total IgG in B6 mice possibly suggests the initiation of TLR3-dependent pathway early during P. yoelii infection. Our results thus reveal a new mechanism in which a parasite-activated TLR3 pathway promotes blood stage infection along with quantitative and qualitative differences in Ab responses.