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1.
Nat Commun ; 12(1): 1988, 2021 03 31.
Artigo em Inglês | MEDLINE | ID: mdl-33790291

RESUMO

Bacteria respond to environmental changes by inducing transcription of some genes and repressing others. Sialic acids, which coat human cell surfaces, are a nutrient source for pathogenic and commensal bacteria. The Escherichia coli GntR-type transcriptional repressor, NanR, regulates sialic acid metabolism, but the mechanism is unclear. Here, we demonstrate that three NanR dimers bind a (GGTATA)3-repeat operator cooperatively and with high affinity. Single-particle cryo-electron microscopy structures reveal the DNA-binding domain is reorganized to engage DNA, while three dimers assemble in close proximity across the (GGTATA)3-repeat operator. Such an interaction allows cooperative protein-protein interactions between NanR dimers via their N-terminal extensions. The effector, N-acetylneuraminate, binds NanR and attenuates the NanR-DNA interaction. The crystal structure of NanR in complex with N-acetylneuraminate reveals a domain rearrangement upon N-acetylneuraminate binding to lock NanR in a conformation that weakens DNA binding. Our data provide a molecular basis for the regulation of bacterial sialic acid metabolism.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas de Escherichia coli/metabolismo , Escherichia coli/metabolismo , Proteínas Repressoras/metabolismo , Ácidos Siálicos/metabolismo , Regulação Alostérica , Sequência de Bases , Sítios de Ligação/genética , Cristalografia por Raios X , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Escherichia coli/genética , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica , Modelos Moleculares , Ácido N-Acetilneuramínico/metabolismo , Motivos de Nucleotídeos/genética , Ligação Proteica , Conformação Proteica , Multimerização Proteica , Proteínas Repressoras/genética
2.
Nat Commun ; 12(1): 2149, 2021 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-33846319

RESUMO

Reovirus infection requires the concerted action of viral and host factors to promote cell entry. After interaction of reovirus attachment protein σ1 with cell-surface carbohydrates and proteinaceous receptors, additional host factors mediate virus internalization. In particular, ß1 integrin is required for endocytosis of reovirus virions following junctional adhesion molecule A (JAM-A) binding. While integrin-binding motifs in the surface-exposed region of reovirus capsid protein λ2 are thought to mediate integrin interaction, evidence for direct ß1 integrin-reovirus interactions and knowledge of how integrins function to mediate reovirus entry is lacking. Here, we use single-virus force spectroscopy and confocal microscopy to discover a direct interaction between reovirus and ß1 integrins. Comparison of interactions between reovirus disassembly intermediates as well as mutants and ß1 integrin show that λ2 is the integrin ligand. Finally, using fluidic force microscopy, we demonstrate a functional role for ß1 integrin interaction in promoting clathrin recruitment to cell-bound reovirus. Our study demonstrates a direct interaction between reovirus and ß1 integrins and offers insights into the mechanism of reovirus cell entry. These results provide new perspectives for the development of efficacious antiviral therapeutics and the engineering of improved viral gene delivery and oncolytic vectors.


Assuntos
Clatrina/metabolismo , Interações Hospedeiro-Patógeno , Integrina beta1/metabolismo , Reoviridae/fisiologia , Animais , Sítios de Ligação , Capsídeo/metabolismo , Cátions , Linhagem Celular , Membrana Celular/metabolismo , Endocitose , Cinética , Camundongos , Ácido N-Acetilneuramínico/metabolismo , Mutação Puntual/genética , Ligação Proteica , Termodinâmica , Proteínas Virais/metabolismo , Vírion/metabolismo
3.
AAPS PharmSciTech ; 22(3): 89, 2021 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-33665749

RESUMO

It is well known that neutrophil-mediated delivery of therapeutic agents is a promising method for treating tumors. However, owing to the limited number and limited uptake ability of neutrophils, determining a reasonable dose has become an urgent problem to be solved. Furthermore, the number of nanoparticles is far greater than the number of neutrophils at normal doses, which causes excessive nanoparticles to reach nontargeted organs or tissues, leading to serious adverse effects. To address these problems, a neutrophil-targeting delivery system (DiR-DADGC-L) based on DiR-labeled and butanedioic acid (DA)-linked 5-amino-3,5-dideoxy-D-Glycerol-D-galactonanulose-cholesterol conjugate (DADGC) was designed to improve the efficiency of hitchhiking neutrophils through the specific binding of sialic acid (SA) to L-selectin (SA-binding receptor, expressed on neutrophils). DiR-DADGC-L was prepared with favorable particle size and encapsulation efficiency (%EE) to deliver DiR into neutrophils. Subsequently, diverse doses of DiR-DADGC-L were injected intravenously into S180 tumor-bearing and cyclophosphamide-depleted (CTX-D) S180 tumor-bearing mice to evaluate the in vivo behavior of liposomes. The results verified the following: a) The content of DiR-DADGC-L in neutrophils accounts for approximately 14.5% of the content of DiR-DADGC-L in plasma, and the uptake capacity of neutrophils remains unchanged under different doses, and b) both neutrophils and the enhanced permeability and retention (EPR) effect might exert significant roles in tumor treatment. As for the neutrophil-mediated delivery system, higher doses are not necessarily appropriate, and a lower dose may achieve an unexpected effect. It will be wise to determine an optimum dose to improve delivery efficiency.


Assuntos
Antineoplásicos/administração & dosagem , Antineoplásicos/uso terapêutico , Nanopartículas/administração & dosagem , Neoplasias/tratamento farmacológico , Neutrófilos/metabolismo , Animais , Antineoplásicos/farmacocinética , Ciclofosfamida/administração & dosagem , Ciclofosfamida/farmacocinética , Ciclofosfamida/uso terapêutico , Sistemas de Liberação de Medicamentos , Selectina L/metabolismo , Lipossomos , Masculino , Camundongos , Ácido N-Acetilneuramínico/metabolismo , Tamanho da Partícula , Sarcoma 180/tratamento farmacológico , Distribuição Tecidual
4.
Front Cell Infect Microbiol ; 11: 625581, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33659220

RESUMO

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the pandemic Coronavirus Disease 2019 (COVID-19). This virus is highly transmissible among individuals through both droplets and aerosol leading to determine severe pneumonia. Among the various factors that can influence both the onset of disease and the severity of its complications, the microbiome composition has also been investigated. Recent evidence showed the possible relationship between gut, lung, nasopharyngeal, or oral microbiome and COVID-19, but very little is known about it. Therefore, we aimed to verify the relationships between nasopharyngeal microbiome and the development of either COVID-19 or the severity of symptoms. To this purpose, we analyzed, by next generation sequencing, the hypervariable V1-V2-V3 regions of the bacterial 16S rRNA in nasopharyngeal swabs from SARS-CoV-2 infected patients (n=18) and control (CO) individuals (n=12) using Microbiota solution A (Arrow Diagnostics). We found a significant lower abundance of Proteobacteria and Fusobacteria in COVID-19 patients in respect to CO (p=0.003 and p<0.0001, respectively) from the phylum up to the genus (p<0.001). The Fusobacterium periodonticum (FP) resulted as the most significantly reduced species in COVID-19 patients respect to CO. FP is reported as being able to perform the surface sialylation. Noteworthy, some sialic acids residues on the cell surface could work as additional S protein of SARS-CoV-2 receptors. Consequently, SARS-CoV-2 could use sialic acids as receptors to bind to the epithelium of the respiratory tract, promoting its clustering and the disease development. We can therefore speculate that the significant reduction of FP in COVID-19 patients could be directly or indirectly linked to the modulation of sialic acid metabolism. Finally, viral or environmental factors capable of interfering with sialic metabolism could determine a fall in the individual protection from SARS-CoV-2. Further studies are necessary to clarify the precise role of FP in COVID-19.


Assuntos
/epidemiologia , Infecções por Fusobacterium/microbiologia , Fusobacterium/crescimento & desenvolvimento , Microbiota , Ácido N-Acetilneuramínico/metabolismo , Pandemias , /isolamento & purificação , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Fusobacterium/genética , Humanos , Masculino , Pessoa de Meia-Idade , Boca/microbiologia , Nasofaringe/microbiologia
5.
Int J Mol Sci ; 22(3)2021 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-33540792

RESUMO

The skin barrier consists of mucus, primarily comprising highly glycosylated mucins, and the epithelium. Host mucin glycosylation governs interactions with pathogens and stress is associated with impaired epithelial barrier function. We characterized Atlantic salmon skin barrier function during chronic stress (high density) and mucin O-glycosylation changes in response to acute and chronic stress. Fish held at low (LD: 14-30 kg/m3) and high densities (HD: 50-80 kg/m3) were subjected to acute stress 24 h before sampling at 17 and 21 weeks after start of the experiment. Blood parameters indicated primary and secondary stress responses at both sampling points. At the second sampling, skin barrier function towards molecules was reduced in the HD compared to the LD group (Papp mannitol; p < 0.01). Liquid chromatography-mass spectrometry revealed 81 O-glycan structures from the skin. Fish subjected to both chronic and acute stress had an increased proportion of large O-glycan structures. Overall, four of the O-glycan changes have potential as indicators of stress, especially for the combined chronic and acute stress. Stress thus impairs skin barrier function and induces glycosylation changes, which have potential to both affect interactions with pathogens and serve as stress indicators.


Assuntos
Aglomeração , Mucinas/metabolismo , Muco/química , Ácido N-Acetilneuramínico/metabolismo , Polissacarídeos/metabolismo , Salmo salar/metabolismo , Absorção Cutânea/fisiologia , Pele/metabolismo , Estresse Fisiológico/fisiologia , Estresse Psicológico/metabolismo , Animais , Biomarcadores , Cromatografia Líquida , Aglomeração/psicologia , Glicosilação , Hidrocortisona/sangue , Manitol/farmacocinética , Espectrometria de Massas , Mucinas/isolamento & purificação , Muco/metabolismo , Ácido N-Acetilneuramínico/isolamento & purificação , Oxigênio/análise , Polissacarídeos/isolamento & purificação , Processamento de Proteína Pós-Traducional , Salmo salar/sangue , Pele/ultraestrutura , Temperatura , Qualidade da Água
6.
PLoS Pathog ; 17(1): e1009222, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33465168

RESUMO

Bacterial binding to platelets is a key step in the development of infective endocarditis (IE). Sialic acid, a common terminal carbohydrate on host glycans, is the major receptor for streptococci on platelets. So far, all defined interactions between streptococci and sialic acid on platelets are mediated by serine-rich repeat proteins (SRRPs). However, we identified Streptococcus oralis subsp. oralis IE-isolates that bind sialic acid but lack SRRPs. In addition to binding sialic acid, some SRRP- isolates also bind the cryptic receptor ß-1,4-linked galactose through a yet unknown mechanism. Using comparative genomics, we identified a novel sialic acid-binding adhesin, here named AsaA (associated with sialic acid adhesion A), present in IE-isolates lacking SRRPs. We demonstrated that S. oralis subsp. oralis AsaA is required for binding to platelets in a sialic acid-dependent manner. AsaA comprises a non-repeat region (NRR), consisting of a FIVAR/CBM and two Siglec-like and Unique domains, followed by 31 DUF1542 domains. When recombinantly expressed, Siglec-like and Unique domains competitively inhibited binding of S. oralis subsp. oralis and directly interacted with sialic acid on platelets. We further demonstrated that AsaA impacts the pathogenesis of S. oralis subsp. oralis in a rabbit model of IE. Additionally, we found AsaA orthologues in other IE-causing species and demonstrated that the NRR of AsaA from Gemella haemolysans blocked binding of S. oralis subsp. oralis, suggesting that AsaA contributes to the pathogenesis of multiple IE-causing species. Finally, our findings provide evidence that sialic acid is a key factor for bacterial-platelets interactions in a broader range of species than previously appreciated, highlighting its potential as a therapeutic target.


Assuntos
Adesinas Bacterianas/metabolismo , Aderência Bacteriana , Proteínas de Bactérias/metabolismo , Endocardite Bacteriana/patologia , Ácido N-Acetilneuramínico/metabolismo , Streptococcus/metabolismo , Adesinas Bacterianas/genética , Animais , Proteínas de Bactérias/genética , Endocardite Bacteriana/metabolismo , Endocardite Bacteriana/microbiologia , Masculino , Coelhos , Streptococcus/classificação , Streptococcus/genética , Streptococcus/isolamento & purificação
7.
AAPS PharmSciTech ; 22(1): 16, 2021 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-33389218

RESUMO

Many anti-inflammatory therapies targeting neutrophils have been developed so far. A sialic acid (SA)-modified liposomal (SAL) formulation, based on the high expression of L-selectin in peripheral blood neutrophils (PBNs) and SA as its targeting ligand, has proved to be an effective neutrophil-mediated drug delivery system targeting rheumatoid arthritis (RA). The objective of this study was to investigate the influence of particle size of drug-carrying SALs transported and delivered by neutrophils on their anti-RA effect. Dexamethasone palmitate-loaded SALs (DP-SALs) of different particle sizes (300.2 ± 5.5 nm, 150.3 ± 4.3 nm, and 75.0 ± 3.9 nm) were prepared with DP as a model drug. Our study indicated that DP-SALs could efficiently target PBNs, with larger liposomes leading to higher drug accumulation in cells. However, a high intake of large DP-SALs by PBNs inhibited their migration ability and capacity to release the payload at the target site. In contrast, small DP-SALs (75.0 ± 3.9 nm) could maintain the drug delivery potential of PBNs, leading to their efficient accumulation at the inflammatory site, where PBNs would be excessively activated to form neutrophil extracellular traps along with efficient payload release (small DP-SALs) and finally to induce excellent anti-RA effect.


Assuntos
Anti-Inflamatórios/administração & dosagem , Artrite Reumatoide/tratamento farmacológico , Dexametasona/administração & dosagem , Lipossomos/química , Neutrófilos/efeitos dos fármacos , Ácidos Siálicos/química , Animais , Anti-Inflamatórios/uso terapêutico , Dexametasona/uso terapêutico , Sistemas de Liberação de Medicamentos , Humanos , Masculino , Ácido N-Acetilneuramínico/metabolismo , Ácido N-Acetilneuramínico/farmacologia , Ácido N-Acetilneuramínico/uso terapêutico , Tamanho da Partícula , Ratos , Ratos Wistar
8.
Nat Commun ; 11(1): 5078, 2020 10 08.
Artigo em Inglês | MEDLINE | ID: mdl-33033266

RESUMO

Metabolic engineering facilitates chemical biosynthesis by rewiring cellular resources to produce target compounds. However, an imbalance between cell growth and bioproduction often reduces production efficiency. Genetic code expansion (GCE)-based orthogonal translation systems incorporating non-canonical amino acids (ncAAs) into proteins by reassigning non-canonical codons to ncAAs qualify for balancing cellular metabolism. Here, GCE-based cell growth and biosynthesis balance engineering (GCE-CGBBE) is developed, which is based on titrating expression of cell growth and metabolic flux determinant genes by constructing ncAA-dependent expression patterns. We demonstrate GCE-CGBBE in genome-recoded Escherichia coli Δ321AM by precisely balancing glycolysis and N-acetylglucosamine production, resulting in a 4.54-fold increase in titer. GCE-CGBBE is further expanded to non-genome-recoded Bacillus subtilis to balance growth and N-acetylneuraminic acid bioproduction by titrating essential gene expression, yielding a 2.34-fold increase in titer. Moreover, the development of ncAA-dependent essential gene expression regulation shows efficient biocontainment of engineered B. subtilis to avoid unintended proliferation in nature.


Assuntos
Acetilglucosamina/metabolismo , Bacillus subtilis/crescimento & desenvolvimento , Vias Biossintéticas , Escherichia coli/crescimento & desenvolvimento , Ácido N-Acetilneuramínico/metabolismo , Bacillus subtilis/metabolismo , Proliferação de Células , Escherichia coli/metabolismo , Código Genético , Proteínas de Fluorescência Verde/metabolismo , Engenharia Metabólica , Análise do Fluxo Metabólico , Regiões Promotoras Genéticas/genética , RNA de Transferência/genética , Tirosina/metabolismo
9.
Nat Commun ; 11(1): 5104, 2020 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-33037214

RESUMO

Many intestinal pathogens, including Clostridioides difficile, use mucus-derived sugars as crucial nutrients in the gut. Commensals that compete with pathogens for such nutrients are therefore ecological gatekeepers in healthy guts, and are attractive candidates for therapeutic interventions. Nevertheless, there is a poor understanding of which commensals use mucin-derived sugars in situ as well as their potential to impede pathogen colonization. Here, we identify mouse gut commensals that utilize mucus-derived monosaccharides within complex communities using single-cell stable isotope probing, Raman-activated cell sorting and mini-metagenomics. Sequencing of cell-sorted fractions reveals members of the underexplored family Muribaculaceae as major mucin monosaccharide foragers, followed by members of Lachnospiraceae, Rikenellaceae, and Bacteroidaceae families. Using this information, we assembled a five-member consortium of sialic acid and N-acetylglucosamine utilizers that impedes C. difficile's access to these mucosal sugars and impairs pathogen colonization in antibiotic-treated mice. Our findings underscore the value of targeted approaches to identify organisms utilizing key nutrients and to rationally design effective probiotic mixtures.


Assuntos
/patogenicidade , Microbioma Gastrointestinal/fisiologia , Monossacarídeos/metabolismo , Acetilglucosamina/metabolismo , Animais , Antibacterianos , Proteínas de Bactérias/metabolismo , Toxinas Bacterianas/metabolismo , Separação Celular/métodos , /crescimento & desenvolvimento , Infecções por Clostridium/microbiologia , Deutério , Feminino , Mucinas Gástricas/química , Mucinas Gástricas/metabolismo , Mucosa Intestinal/efeitos dos fármacos , Mucosa Intestinal/microbiologia , Metagenoma , Camundongos Endogâmicos C57BL , Ácido N-Acetilneuramínico/metabolismo , Polissacarídeos/química , Polissacarídeos/metabolismo , Análise Espectral Raman
10.
Nat Commun ; 11(1): 4646, 2020 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-32938911

RESUMO

The human betacoronaviruses HKU1 and OC43 (subgenus Embecovirus) arose from separate zoonotic introductions, OC43 relatively recently and HKU1 apparently much longer ago. Embecovirus particles contain two surface projections called spike (S) and haemagglutinin-esterase (HE), with S mediating receptor binding and membrane fusion, and HE acting as a receptor-destroying enzyme. Together, they promote dynamic virion attachment to glycan-based receptors, specifically 9-O-acetylated sialic acid. Here we present the cryo-EM structure of the ~80 kDa, heavily glycosylated HKU1 HE at 3.4 Å resolution. Comparison with existing HE structures reveals a drastically truncated lectin domain, incompatible with sialic acid binding, but with the structure and function of the esterase domain left intact. Cryo-EM and mass spectrometry analysis reveals a putative glycan shield on the now redundant lectin domain. The findings further our insight into the evolution and host adaptation of human embecoviruses, and demonstrate the utility of cryo-EM for studying small, heavily glycosylated proteins.


Assuntos
Betacoronavirus/química , Betacoronavirus/fisiologia , Infecções por Coronavirus/virologia , Hemaglutininas Virais/química , Proteínas Virais de Fusão/química , Betacoronavirus/classificação , Sítios de Ligação , Domínio Catalítico , Microscopia Crioeletrônica , Glicosilação , Células HEK293 , Hemaglutininas Virais/metabolismo , Hemaglutininas Virais/ultraestrutura , Humanos , Lectinas/química , Lectinas/metabolismo , Espectrometria de Massas , Modelos Moleculares , Ácido N-Acetilneuramínico/metabolismo , Polissacarídeos/química , Domínios Proteicos , Proteínas Virais de Fusão/metabolismo , Proteínas Virais de Fusão/ultraestrutura
11.
PLoS One ; 15(9): e0239488, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32946496

RESUMO

The immunopathogenesis of H5N1 virus has been studied intensively since it caused cross-species infection and induced high mortality to human. We previously observed the interaction between monocytes and B cells, which increased the susceptibility of B cell to H5N1 virus infection after a co-culture. Levels of α2,3 sialic acid (avian flu receptor) were also significantly increased on B cell surface in this co-culture model with unclear explanation. In this study, we aimed to determine the possible mechanism that responded for this increase in α2,3 sialic acid on B cells. Acquisition of α2,3 SA by B cells via cell contact-dependent trogocytosis was proposed. Results showed that the lack of α2,3 SA was detected on B cell surface, and B cells acquired membrane-bound α2,3 SA molecules from monocytes in H5N1-infected co-cultures. Occurrence of membrane exchange mainly relied on H5N1 infection and cell-cell contact as opposed to a mock infection and transwell. The increase in α2,3 SA on B cell surface mediated by trogocytosis was associated with the enhanced susceptibility to H5N1 infection. These observations thus provide the evidence that H5N1 influenza virus may utilize trogocytosis to expand its cell tropism and spread to immune cells despite the lack of avian flu receptor.


Assuntos
Linfócitos B/imunologia , Linfócitos B/virologia , Virus da Influenza A Subtipo H5N1/imunologia , Virus da Influenza A Subtipo H5N1/patogenicidade , Influenza Humana/imunologia , Influenza Humana/virologia , Monócitos/imunologia , Ácido N-Acetilneuramínico/imunologia , Animais , Apresentação do Antígeno , Linfócitos B/metabolismo , Aves , Comunicação Celular/imunologia , Técnicas de Cocultura , Humanos , Influenza Aviária/imunologia , Influenza Aviária/virologia , Monócitos/metabolismo , Monócitos/virologia , Ácido N-Acetilneuramínico/metabolismo , Receptores Virais/imunologia , Receptores Virais/metabolismo
12.
Viruses ; 12(9)2020 08 19.
Artigo em Inglês | MEDLINE | ID: mdl-32825063

RESUMO

COVID-19 novel coronavirus (CoV) disease caused by severe acquired respiratory syndrome (SARS)-CoV-2 manifests severe lethal respiratory illness in humans and has recently developed into a worldwide pandemic. The lack of effective treatment strategy and vaccines against the SARS-CoV-2 poses a threat to human health. An extremely high infection rate and multi-organ secondary infection within a short period of time makes this virus more deadly and challenging for therapeutic interventions. Despite high sequence similarity and utilization of common host-cell receptor, human angiotensin-converting enzyme-2 (ACE2) for virus entry, SARS-CoV-2 is much more infectious than SARS-CoV. Structure-based sequence comparison of the N-terminal domain (NTD) of the spike protein of Middle East respiratory syndrome (MERS)-CoV, SARS-CoV, and SARS-CoV-2 illustrate three divergent loop regions in SARS-CoV-2, which is reminiscent of MERS-CoV sialoside binding pockets. Comparative binding analysis with host sialosides revealed conformational flexibility of SARS-CoV-2 divergent loop regions to accommodate diverse glycan-rich sialosides. These key differences with SARS-CoV and similarity with MERS-CoV suggest an evolutionary adaptation of SARS-CoV-2 spike glycoprotein reciprocal interaction with host surface sialosides to infect host cells with wide tissue tropism.


Assuntos
Betacoronavirus/química , Coronavírus da Síndrome Respiratória do Oriente Médio/química , Ácidos Siálicos/metabolismo , Glicoproteína da Espícula de Coronavírus/química , Amino Açúcares/metabolismo , Betacoronavirus/fisiologia , Sítios de Ligação , Modelos Moleculares , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Ácido N-Acetilneuramínico/metabolismo , Ligação Proteica , Domínios Proteicos , Receptores Virais/química , Receptores Virais/metabolismo , Vírus da SARS/química , Antígeno Sialil Lewis X/metabolismo , Glicoproteína da Espícula de Coronavírus/metabolismo , Tropismo Viral , Internalização do Vírus
14.
Cells ; 9(9)2020 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-32854433

RESUMO

Coronaviruses (CoVs) are a diverse family of the enveloped human and animal viruses reported as causative agents for respiratory and intestinal infections. The high pathogenic potential of human CoVs, including SARS-CoV, MERS-CoV and SARS-CoV-2, is closely related to the invasion mechanisms underlying the attachment and entry of viral particles to the host cells. There is increasing evidence that sialylated compounds of cellular glycocalyx can serve as an important factor in the mechanism of CoVs infection. Additionally, the sialic acid-mediated cross-reactivity with the host immune lectins is known to exert the immune response of different intensity in selected pathological stages. Here, we focus on the last findings in the field of glycobiology in the context of the role of sialic acid in tissue tropism, viral entry kinetics and immune regulation in the CoVs infections.


Assuntos
Betacoronavirus/fisiologia , Infecções por Coronavirus/imunologia , Citocinas/metabolismo , Coronavírus da Síndrome Respiratória do Oriente Médio/fisiologia , Ácido N-Acetilneuramínico/metabolismo , Pneumonia Viral/imunologia , Vírus da SARS/fisiologia , Síndrome Respiratória Aguda Grave/imunologia , Animais , Infecções por Coronavirus/virologia , Humanos , Camundongos , Pandemias , Pneumonia Viral/virologia , Receptores de Reconhecimento de Padrão/metabolismo , Síndrome Respiratória Aguda Grave/virologia , Lectinas Semelhantes a Imunoglobulina de Ligação ao Ácido Siálico/metabolismo , Receptores Toll-Like/metabolismo , Internalização do Vírus
15.
J Cancer Res Ther ; 16(3): 605-611, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32719275

RESUMO

Aim: This study aims to assess the usefulness of salivary sialic acid (SA) as a tumor marker in the detection of oral squamous cell carcinoma (OSCC) among tobacco chewers. Materials and Methods: After the approval of study protocol by the Institutional Ethics Committee and informed voluntary consent, salivary samples were collected from 96 participants in each group of tobacco chewers with OSCC, tobacco chewers without precancerous or cancerous lesion, and healthy controls. Salivary protein-bound SA (PBSA) and salivary-free SA (FSA) were measured by Yao et al.'s method of acid ninhydrin reaction, and the data were subjected to appropriate statistical analysis. Results: The salivary PBSA and FSA levels in the Groups 1, 2, and 3 participants were 31.17 ± 7.6 mg/dL and 63.45 ± 9.8 mg/dL, 25.45 ± 16.61 mg/dL and 33.18 ± 11.38 mg/dL, and 22.73 ± 3.01 mg/dL and 21.62 ± 8.86 mg/dL, respectively. Salivary FSA levels were significantly increased among the tobacco chewers with OSCC patients (Group 1) and tobacco chewers with no premalignant lesions of the oral cavity (Group 2) compared to the healthy controls (Group 3) with P < 0.05 being statistically significant. Salivary FSA levels were significantly increased in Group 1 as compared with Group 2. The salivary PBSA was high among Group 1 as compared to the control Group 3; there was however no significant difference in the levels of salivary PBSA between Group 1 and Group 2. There was no significant difference in the PBSA levels between OSCC patients of Group 1 and the tobacco chewers without precancerous or cancerous lesion in the oral cavity of Group 2. Conclusion: Salivary PBSA and FSA are significantly raised in both tobacco chewers with OSCC and in tobacco chewers with no precancerous or cancerous lesions in the oral cavity. SA should therefore be used cautiously while considering it as a marker for the early detection of oral cancer. Tobacco can be a crucial confounding factor when SA is used as a biomarker in OSCC since their levels are elevated to some extent even in tobacco chewers without any clinically obvious precancerous or cancerous lesions in the oral cavity.


Assuntos
Neoplasias Bucais/metabolismo , Ácido N-Acetilneuramínico/metabolismo , Lesões Pré-Cancerosas/metabolismo , Saliva/metabolismo , Carcinoma de Células Escamosas de Cabeça e Pescoço/metabolismo , Uso de Tabaco/efeitos adversos , Uso de Tabaco/metabolismo , Adulto , Biomarcadores Tumorais/metabolismo , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Bucais/induzido quimicamente , Neoplasias Bucais/diagnóstico , Neoplasias Bucais/patologia , Lesões Pré-Cancerosas/induzido quimicamente , Lesões Pré-Cancerosas/diagnóstico , Lesões Pré-Cancerosas/patologia , Saliva/química , Carcinoma de Células Escamosas de Cabeça e Pescoço/etiologia , Carcinoma de Células Escamosas de Cabeça e Pescoço/patologia , Uso de Tabaco/patologia
16.
PLoS Pathog ; 16(7): e1008656, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32639985

RESUMO

Influenza A virus (IAV) binds its host cell using the major viral surface protein hemagglutinin (HA). HA recognizes sialic acid, a plasma membrane glycan that functions as the specific primary attachment factor (AF). Since sialic acid alone cannot fulfill a signaling function, the virus needs to activate downstream factors to trigger endocytic uptake. Recently, the epidermal growth factor receptor (EGFR), a member of the receptor-tyrosine kinase family, was shown to be activated by IAV and transmit cell entry signals. However, how IAV's binding to sialic acid leads to engagement and activation of EGFR remains largely unclear. We used multicolor super-resolution microscopy to study the lateral organization of both IAV's AFs and its functional receptor EGFR at the scale of the IAV particle. Intriguingly, quantitative cluster analysis revealed that AFs and EGFR are organized in partially overlapping submicrometer clusters in the plasma membrane of A549 cells. Within AF domains, the local AF concentration reaches on average 10-fold the background concentration and tends to increase towards the cluster center, thereby representing a multivalent virus-binding platform. Using our experimentally measured cluster characteristics, we simulated virus diffusion on a flat membrane. The results predict that the local AF concentration strongly influences the distinct mobility pattern of IAVs, in a manner consistent with live-cell single-virus tracking data. In contrast to AFs, EGFR resides in smaller clusters. Virus binding activates EGFR, but interestingly, this process occurs without a major lateral EGFR redistribution, indicating the activation of pre-formed clusters, which we show are long-lived. Taken together, our results provide a quantitative understanding of the initial steps of influenza virus infection. Co-clustering of AF and EGFR permit a cooperative effect of binding and signaling at specific platforms, thus linking their spatial organization to their functional role during virus-cell binding and receptor activation.


Assuntos
Vírus da Influenza A/metabolismo , Ácido N-Acetilneuramínico/metabolismo , Receptores Virais/metabolismo , Ligação Viral , Células A549 , Receptores ErbB/metabolismo , Humanos , Vírus da Influenza A/patogenicidade , Influenza Humana/metabolismo , Internalização do Vírus
18.
Blood Adv ; 4(13): 2967-2978, 2020 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-32609845

RESUMO

Thrombocytopenia is a common complication of influenza virus infection, and its severity predicts the clinical outcome of critically ill patients. The underlying cause(s) remain incompletely understood. In this study, in patients with an influenza A/H1N1 virus infection, viral load and platelet count correlated inversely during the acute infection phase. We confirmed this finding in a ferret model of influenza virus infection. In these animals, platelet count decreased with the degree of virus pathogenicity varying from 0% in animals infected with the influenza A/H3N2 virus, to 22% in those with the pandemic influenza A/H1N1 virus, up to 62% in animals with a highly pathogenic A/H5N1 virus infection. This thrombocytopenia is associated with virus-containing platelets that circulate in the blood. Uptake of influenza virus particles by platelets requires binding to sialoglycans and results in the removal of sialic acids by the virus neuraminidase, a trigger for hepatic clearance of platelets. We propose the clearance of influenza virus by platelets as a paradigm. These insights clarify the pathophysiology of influenza virus infection and show how severe respiratory infections, including COVID-19, may propagate thrombocytopenia and/or thromboembolic complications.


Assuntos
Plaquetas/virologia , Vírus da Influenza A/patogenicidade , Influenza Humana/complicações , Ácido N-Acetilneuramínico/metabolismo , Polissacarídeos/metabolismo , Trombocitopenia/etiologia , Animais , Plaquetas/metabolismo , Plaquetas/patologia , Modelos Animais de Doenças , Furões , Interações Hospedeiro-Patógeno , Humanos , Vírus da Influenza A Subtipo H1N1/patogenicidade , Vírus da Influenza A Subtipo H1N1/fisiologia , Vírus da Influenza A Subtipo H3N2/patogenicidade , Vírus da Influenza A Subtipo H3N2/fisiologia , Virus da Influenza A Subtipo H5N1/patogenicidade , Virus da Influenza A Subtipo H5N1/fisiologia , Vírus da Influenza A/fisiologia , Influenza Humana/metabolismo , Influenza Humana/patologia , Influenza Humana/virologia , Infecções por Orthomyxoviridae/complicações , Infecções por Orthomyxoviridae/metabolismo , Infecções por Orthomyxoviridae/patologia , Infecções por Orthomyxoviridae/virologia , Trombocitopenia/metabolismo , Trombocitopenia/patologia , Trombocitopenia/virologia , Internalização do Vírus
19.
Environ Toxicol Pharmacol ; 79: 103436, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32562764

RESUMO

Recent analysis concerning the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)- angiotensin converting enzyme (ACE) receptor interaction in enterocytes, the definition of gut-lung axis, as well as the molecular basis of sialic acid-related dual recognition concept in gastrointestinal SARS-CoV-2 infection, have brought a new perspective to potential therapeutic targets. In this review evolving research and clinical data on gastrointestinal SARS-CoV-2 infection are discussed in the context of viral fusion and entry mechanisms, focusing on the different triggers used by coronaviruses. Furthermore, it is emphasized that the viral spike protein is prevented from binding gangliosides, which are composed of a glycosphingolipid with one or more sialic acids, in the presence of chloroquine or hydroxychloroquine. In gastrointestinal SARS-CoV-2 infection the efficiency of these repositioned drugs is debated.


Assuntos
Betacoronavirus , Infecções por Coronavirus/metabolismo , Gastroenteropatias/metabolismo , Gastroenteropatias/virologia , Ácido N-Acetilneuramínico/metabolismo , Pneumonia Viral/metabolismo , Antivirais/farmacologia , Infecções por Coronavirus/tratamento farmacológico , Humanos , Pandemias , Pneumonia Viral/tratamento farmacológico , Ligação Viral
20.
Nature ; 582(7811): 265-270, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32499653

RESUMO

Approximately one-third of the world's population suffers from allergies1. Exposure to allergens crosslinks immunoglobulin E (IgE) antibodies that are bound to mast cells and basophils, triggering the release of inflammatory mediators, including histamine2. Although IgE is absolutely required for allergies, it is not understood why total and allergen-specific IgE concentrations do not reproducibly correlate with allergic disease3-5. It is well-established that glycosylation of IgG dictates its effector function and has disease-specific patterns. However, whether IgE glycans differ in disease states or affect biological activity is completely unknown6. Here we perform an unbiased examination of glycosylation patterns of total IgE from individuals with a peanut allergy and from non-atopic individuals without allergies. Our analysis reveals an increase in sialic acid content on total IgE from individuals with a peanut allergy compared with non-atopic individuals. Removal of sialic acid from IgE attenuates effector-cell degranulation and anaphylaxis in several functional models of allergic disease. Therapeutic interventions-including removing sialic acid from cell-bound IgE with a neuraminidase enzyme targeted towards the IgE receptor FcεRI, and administering asialylated IgE-markedly reduce anaphylaxis. Together, these results establish IgE glycosylation, and specifically sialylation, as an important regulator of allergic disease.


Assuntos
Imunoglobulina E/química , Imunoglobulina E/imunologia , Ácido N-Acetilneuramínico/análise , Hipersensibilidade a Amendoim/imunologia , Hipersensibilidade a Amendoim/patologia , Adolescente , Adulto , Idoso , Alérgenos/imunologia , Anafilaxia/imunologia , Animais , Estudos de Casos e Controles , Degranulação Celular/imunologia , Criança , Pré-Escolar , Feminino , Glicosilação , Humanos , Imunoglobulina E/efeitos adversos , Imunoglobulina E/farmacologia , Lactente , Recém-Nascido , Masculino , Camundongos , Pessoa de Meia-Idade , Modelos Imunológicos , Ácido N-Acetilneuramínico/química , Ácido N-Acetilneuramínico/metabolismo , Neuraminidase/metabolismo , Receptores de IgE/metabolismo , Adulto Jovem
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