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1.
Nat Commun ; 11(1): 4844, 2020 09 24.
Artigo em Inglês | MEDLINE | ID: mdl-32973204

RESUMO

Akkermansia muciniphila is a mucin-degrading bacterium commonly found in the human gut that promotes a beneficial effect on health, likely based on the regulation of mucus thickness and gut barrier integrity, but also on the modulation of the immune system. In this work, we focus in OgpA from A. muciniphila, an O-glycopeptidase that exclusively hydrolyzes the peptide bond N-terminal to serine or threonine residues substituted with an O-glycan. We determine the high-resolution X-ray crystal structures of the unliganded form of OgpA, the complex with the glycodrosocin O-glycopeptide substrate and its product, providing a comprehensive set of snapshots of the enzyme along the catalytic cycle. In combination with O-glycopeptide chemistry, enzyme kinetics, and computational methods we unveil the molecular mechanism of O-glycan recognition and specificity for OgpA. The data also contribute to understanding how A. muciniphila processes mucins in the gut, as well as analysis of post-translational O-glycosylation events in proteins.


Assuntos
Microbioma Gastrointestinal/fisiologia , Mucinas/metabolismo , Peptídeo-N4-(N-acetil-beta-glucosaminil) Asparagina Amidase/química , Peptídeo-N4-(N-acetil-beta-glucosaminil) Asparagina Amidase/metabolismo , Verrucomicrobia/metabolismo , Animais , Sítios de Ligação , Cristalografia por Raios X , Glicopeptídeos/química , Humanos , Mamíferos , Simulação de Acoplamento Molecular , Mucina-1/metabolismo , Polissacarídeos/química , Conformação Proteica , Alinhamento de Sequência , Verrucomicrobia/enzimologia
2.
Ecotoxicol Environ Saf ; 204: 111072, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32758694

RESUMO

Zearalenone (ZEN) is a mycotoxin that causes serious health problems in humans and animals. However, few studies have focused on the destruction of the intestinal barrier caused by ZEN. In this study, rats were exposed to different dosages of ZEN (0, 0.2, 1.0 and 5.0 mg/kg bw) by gavage for 4 weeks. The results showed that 1.0 and 5.0 mg/kg ZEN impaired gut morphology, induced the inflammatory response, reduced mucin expression, increased intestinal permeability, decreased the expression of TJ proteins and activated the RhoA/ROCK pathway. However, 0.2 mg/kg ZEN had no significant effect on intestinal barrier except for reducing the expression of some TJ proteins and mucins. Moreover, exposure to ZEN led to slight imbalance in microbiota. In conclusion, ZEN exposure resulted in intestinal barrier dysfunction by inducing intestinal microbiota dysbiosis, decreasing the expression of TJ proteins, activating the RhoA/ROCK pathway, and inducing the inflammatory response.


Assuntos
Microbioma Gastrointestinal/efeitos dos fármacos , Mucosa Intestinal/efeitos dos fármacos , Jejuno/efeitos dos fármacos , Zearalenona/toxicidade , Animais , Relação Dose-Resposta a Droga , Disbiose/induzido quimicamente , Feminino , Microbioma Gastrointestinal/genética , Humanos , Mucosa Intestinal/metabolismo , Mucosa Intestinal/microbiologia , Mucosa Intestinal/patologia , Jejuno/microbiologia , Jejuno/patologia , Masculino , Mucinas/metabolismo , Permeabilidade , Ratos , Ratos Sprague-Dawley , Transdução de Sinais , Quinases Associadas a rho/metabolismo , Proteína rhoA de Ligação ao GTP/metabolismo
3.
Nat Commun ; 11(1): 4017, 2020 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-32782292

RESUMO

The thick mucus layer of the gut provides a barrier to infiltration of the underlying epithelia by both the normal microbiota and enteric pathogens. Some members of the microbiota utilise mucin glycoproteins as a nutrient source, but a detailed understanding of the mechanisms used to breakdown these complex macromolecules is lacking. Here we describe the discovery and characterisation of endo-acting enzymes from prominent mucin-degrading bacteria that target the polyLacNAc structures within oligosaccharide side chains of both animal and human mucins. These O-glycanases are part of the large and diverse glycoside hydrolase 16 (GH16) family and are often lipoproteins, indicating that they are surface located and thus likely involved in the initial step in mucin breakdown. These data provide a significant advance in our knowledge of the mechanism of mucin breakdown by the normal microbiota. Furthermore, we also demonstrate the potential use of these enzymes as tools to explore changes in O-glycan structure in a number of intestinal disease states.


Assuntos
Microbioma Gastrointestinal , Hexosaminidases/metabolismo , Glicoproteínas de Membrana/metabolismo , Mucinas/metabolismo , Animais , Bactérias/classificação , Bactérias/enzimologia , Bactérias/genética , Bactérias/metabolismo , Cristalografia por Raios X , Glicosídeo Hidrolases/genética , Glicosídeo Hidrolases/metabolismo , Hexosaminidases/química , Hexosaminidases/genética , Humanos , Glicoproteínas de Membrana/química , Estrutura Molecular , Mucinas/química , Filogenia , Polissacarídeos/química , Polissacarídeos/metabolismo , Relação Estrutura-Atividade , Especificidade por Substrato
4.
Acta Cytol ; 64(6): 556-562, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32814324

RESUMO

OBJECTIVE: To investigate the cytological findings of lobular endocervical glandular hyperplasia (LEGH) associated with adenocarcinoma and to clarify its characteristics and the coexisting adenocarcinoma using histochemistry and immunohistochemistry. METHODS: Eighteen surgical cases of LEGH of the uterine cervix were retrospectively reviewed and classified into 3 groups: pure (pure type), atypical (atypical type), and LEGH with adenocarcinoma (mixed type). The mixed type is defined as LEGH or atypical LEGH with in situ or invasive adenocarcinoma. Cytological findings of conventional endocervical smear specimens (Papanicolaou stain) were analyzed. Histochemistry (periodic acid-Schiff reaction) and immunohistochemistry (M-GGMC-1, Muc-6 glycoprotein, and Ki-67) were performed using tissue specimens. RESULTS: Cytologically, the pure type (7 cases) is characterized by glandular cell clusters that tended to form monolayered sheets with uniformly small nuclei and contain golden-yellowish mucin, whereas atypical (5 cases) and mixed (6 cases) types are characterized by glandular cell clusters similar to those of the pure type, but with complex glandular structures and mucin localization on the surface of glandular cell clusters. Ki-67 labeling index was significantly higher in atypical and mixed types than that in the pure type. Gastric-type mucinous carcinoma (MC-G) was observed in 2 out of 6 cases with mixed type. CONCLUSIONS: LEGH is found to be associated with adenocarcinoma types other than MC-G. Complex glandular structures or mucin localization on the surface of glandular cell clusters may be useful cytological findings to detect atypical and mixed types of LEGH.


Assuntos
Adenocarcinoma/patologia , Colo do Útero/patologia , Hiperplasia/patologia , Neoplasias do Colo do Útero/patologia , Adulto , Feminino , Humanos , Imuno-Histoquímica/métodos , Pessoa de Meia-Idade , Mucinas/metabolismo
5.
Int J Nanomedicine ; 15: 4079-4090, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32606665

RESUMO

Purpose: The aim of this study is to develop efficient localized therapy of sertaconazole nitrate for the treatment of vaginal candidiasis. Methods: Sertaconazole nitrate-loaded cationic liposomes were prepared by thin-film hydration method and coated with different concentrations of pectin (0.05%, 0.1% and 0.2%) to develop mucoadhesive liposomes. The formulated mucoadhesive vesicles were characterized in terms of morphology, entrapment efficiency, particle size, zeta value, mucoadhesive properties and drug release. The selected formula was incorporated into a gel base and further characterized by an ex vivo permeation study in comparison with conventional sertaconazole gel. Also, the in vivo study was performed to assess the efficacy of sertaconazole mucoadhesive liposomal gel in treating rats with vaginal candidiasis. Results: The mucoadhesive liposomes were spherical. Coating liposomes with pectin results in increased entrapment efficiency and particle size compared with uncoated vesicles. On the contrary, zeta values were reduced upon coating liposomes with pectin indicating efficient coating of liposomes with pectin. Mucoadhesive liposomes showed a more prolonged and sustained drug release compared with uncoated liposomes. Ex vivo study results showed that mucoadhesive liposomal gel increased sertaconazole tissue retention and reduced drug tissue penetration. In the invivo study, the mucoadhesive liposomal gel showed a significant reduction in the microbial count with a subsequent reduction in inflammatory responses with the lowest histopathological change compared with conventional gel. Conclusion: The study confirmed the potentiality of employing mucoadhesive liposomes as a successful carrier for the vaginal delivery of antifungal drugs.


Assuntos
Antifúngicos/uso terapêutico , Candidíase Vulvovaginal/tratamento farmacológico , Imidazóis/uso terapêutico , Muco/química , Tiofenos/uso terapêutico , Adesividade , Animais , Anti-Infecciosos/farmacologia , Biomarcadores/metabolismo , Preparações de Ação Retardada , Liberação Controlada de Fármacos , Feminino , Géis , Humanos , Imidazóis/farmacologia , Imunoglobulina G/metabolismo , Imunoglobulina M/metabolismo , Mediadores da Inflamação/metabolismo , Lipossomos/ultraestrutura , Mucinas/metabolismo , Tamanho da Partícula , Ratos Sprague-Dawley , Ovinos , Eletricidade Estática , Tiofenos/farmacologia , Vagina/patologia , beta-Glucanas/metabolismo
6.
Nat Commun ; 11(1): 3285, 2020 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-32620774

RESUMO

The early life human gut microbiota exerts life-long health effects on the host, but the mechanisms underpinning its assembly remain elusive. Particularly, the early colonization of Clostridiales from the Roseburia-Eubacterium group, associated with protection from colorectal cancer, immune- and metabolic disorders is enigmatic. Here, we describe catabolic pathways that support the growth of Roseburia and Eubacterium members on distinct human milk oligosaccharides (HMOs). The HMO pathways, which include enzymes with a previously unknown structural fold and specificity, were upregulated together with additional glycan-utilization loci during growth on selected HMOs and in co-cultures with Akkermansia muciniphila on mucin, suggesting an additional role in enabling cross-feeding and access to mucin O-glycans. Analyses of 4599 Roseburia genomes underscored the preponderance and diversity of the HMO utilization loci within the genus. The catabolism of HMOs by butyrate-producing Clostridiales may contribute to the competitiveness of this group during the weaning-triggered maturation of the microbiota.


Assuntos
Butiratos/metabolismo , Clostridiales/metabolismo , Leite Humano/metabolismo , Mucinas/metabolismo , Oligossacarídeos/metabolismo , Bifidobacterium/metabolismo , Clostridiales/genética , Colo/microbiologia , Eubacterium/metabolismo , Microbioma Gastrointestinal/fisiologia , Humanos , Lactente , Recém-Nascido , Metabolismo/fisiologia , Leite Humano/química , Polissacarídeos/metabolismo , Verrucomicrobia/metabolismo , Desmame
7.
Am J Pathol ; 190(9): 1823-1832, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32561135

RESUMO

Leukotriene B4 (LTB4) is a major proinflammatory mediator important in host defense, whereas resolvins (Rvs) are produced during the resolution phase of inflammation. The authors determined the actions of both RvE1 and RvD1 on LTB4-induced responses of goblet cells cultured from rat conjunctiva. The responses measured were an increase in the intracellular [Ca2+] ([Ca2+]i) and high-molecular-weight glycoprotein secretion. Treatment with RvE1 or RvD1 for 30 minutes significantly blocked the LTB4-induced [Ca2+]i increase. The actions of RvE1 on LTB4-induced [Ca2+]i increase were reversed by siRNA for the RvE1 receptor, and the actions of RvD1 were reversed by an RvD1 receptor inhibitor. The RvE1 and RvD1 block of LTB4-stimulated increase in [Ca2+]i was also reversed by an inhibitory peptide to ß-adrenergic receptor kinase. LTB4 and block of the LTB4-stimulated increase in [Ca2+]i by RvE1 and RvD1 were partially mediated by the depletion of intracellular Ca2+ stores. RvE1, but not RvD1, counterregulated the LTB4-induced high-molecular-weight glycoprotein secretion. Thus, both RvE1 and RvD1 receptors directly inhibit LTB4 by phosphorylating the LTB4 receptor using ß adrenergic receptor kinase. RvE1 receptor counterregulates the LTB4-induced increase in [Ca2+]i and secretion, whereas RvD1 receptor only counterregulates LTB4-induced [Ca2+]i increase.


Assuntos
Cálcio/metabolismo , Túnica Conjuntiva/metabolismo , Ácido Eicosapentaenoico/análogos & derivados , Células Caliciformes/metabolismo , Leucotrieno B4/metabolismo , Mucinas/metabolismo , Animais , Ácido Eicosapentaenoico/metabolismo , Masculino , Ratos , Ratos Sprague-Dawley
8.
J Biotechnol ; 318: 31-38, 2020 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-32387450

RESUMO

Norovirus infections cause severe gastroenteritis in millions of people every year. Infection requires the recognition of histo-blood group antigens (HBGAs), but such interactions can be inhibited by human milk oligosaccharides (HMOs), which act as structurally-similar decoys. HMO supplements could help to prevent norovirus infections, but the industrial production of complex HMOs is challenging. Here we describe a large-scale fermentation process that yields several kilograms of lacto-N-fucopentaose I (LNFP I). The product was synthesized in Escherichia coli BL21(DE3) cells expressing a recombinant N-acetylglucosaminyltransferase, ß(1,3)galactosyltransferase and α(1,2)fucosyltransferase. Subsequent in vitro enzymatic conversion produced HBGA types A1 and B1 for norovirus inhibition assays. These carbohydrates inhibited the binding of GII.17 virus-like particles (VLPs) to type A1 and B1 trisaccharides more efficiently than simpler fucosylated HMOs, which were in turn more effective than any non-fucosylated structures. However, we found that the simpler fucosylated HMOs were more effective than complex molecules such as LNFP I when inhibiting the binding of GII.17 and GII.4 VLPs to human gastric mucins and mucins from human amniotic fluid. Our results show that complex fucosylated HMOs can be produced by large-scale fermentation and that a combination of simple and complex fucosylated structures is more likely to prevent norovirus infections.


Assuntos
Norovirus/efeitos dos fármacos , Oligossacarídeos/metabolismo , Oligossacarídeos/farmacologia , Receptores Virais/metabolismo , Biotecnologia , Antígenos de Grupos Sanguíneos/química , Antígenos de Grupos Sanguíneos/metabolismo , Antígenos de Grupos Sanguíneos/farmacologia , Fermentação , Humanos , Concentração Inibidora 50 , Leite Humano/química , Mucinas/metabolismo , Norovirus/fisiologia , Oligossacarídeos/química , Trissacarídeos/metabolismo
9.
Proc Natl Acad Sci U S A ; 117(23): 12643-12650, 2020 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-32457151

RESUMO

The mechanism(s) by which cell-tethered mucins modulate infection by influenza A viruses (IAVs) remain an open question. Mucins form both a protective barrier that can block virus binding and recruit IAVs to bind cells via the sialic acids of cell-tethered mucins. To elucidate the molecular role of mucins in flu pathogenesis, we constructed a synthetic glycocalyx to investigate membrane-tethered mucins in the context of IAV binding and fusion. We designed and synthesized lipid-tethered glycopolypeptide mimics of mucins and added them to lipid bilayers, allowing chemical control of length, glycosylation, and surface density of a model glycocalyx. We observed that the mucin mimics undergo a conformational change at high surface densities from a compact to an extended architecture. At high surface densities, asialo mucin mimics inhibited IAV binding to underlying glycolipid receptors, and this density correlated to the mucin mimic's conformational transition. Using a single virus fusion assay, we observed that while fusion of virions bound to vesicles coated with sialylated mucin mimics was possible, the kinetics of fusion was slowed in a mucin density-dependent manner. These data provide a molecular model for a protective mechanism by mucins in IAV infection, and therefore this synthetic glycocalyx provides a useful reductionist model for studying the complex interface of host-pathogen interactions.


Assuntos
Glicocálix/virologia , Vírus da Influenza A/fisiologia , Bicamadas Lipídicas/química , Mucinas/metabolismo , Internalização do Vírus , Glicocálix/química , Mucinas/química , Ácido N-Acetilneuramínico/química , Ácido N-Acetilneuramínico/metabolismo , Peptídeos/química , Peptídeos/metabolismo , Conformação Proteica
10.
Nat Commun ; 11(1): 2265, 2020 05 13.
Artigo em Inglês | MEDLINE | ID: mdl-32404934

RESUMO

The mucosal epithelium secretes a host of protective disulfide-rich peptides, including the trefoil factors (TFFs). The TFFs increase the viscoelasticity of the mucosa and promote cell migration, though the molecular mechanisms underlying these functions have remained poorly defined. Here, we demonstrate that all TFFs are divalent lectins that recognise the GlcNAc-α-1,4-Gal disaccharide, which terminates some mucin-like O-glycans. Degradation of this disaccharide by a glycoside hydrolase abrogates TFF binding to mucins. Structural, mutagenic and biophysical data provide insights into how the TFFs recognise this disaccharide and rationalise their ability to modulate the physical properties of mucus across different pH ranges. These data reveal that TFF activity is dependent on the glycosylation state of mucosal glycoproteins and alludes to a lectin function for trefoil domains in other human proteins.


Assuntos
Lectinas/metabolismo , Muco/metabolismo , Fator Trefoil-1/metabolismo , Fator Trefoil-3/metabolismo , Cristalografia por Raios X , Dissacarídeos/metabolismo , Glicosídeo Hidrolases/metabolismo , Humanos , Ligação de Hidrogênio , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Ligantes , Espectrometria de Massas , Mucinas/metabolismo , Filogenia , Polissacarídeos/metabolismo , Fator Trefoil-1/química , Fator Trefoil-1/genética , Fator Trefoil-3/química , Fator Trefoil-3/genética
11.
PLoS Pathog ; 16(5): e1008342, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32365117

RESUMO

Chitinases are important enzymes that contribute to the generation of carbon and nitrogen from chitin, a long chain polymer of N-acetylglucosamine that is abundant in insects, fungi, invertebrates and fish. Although mammals do not produce chitin, chitinases have been identified in bacteria that are key virulence factors in severe respiratory, gastrointestinal and urinary diseases. However, it is unclear how these enzymes are able to carry out this dual function. Legionella pneumophila is the causative agent of Legionnaires' disease, an often-fatal pneumonia and its chitinase ChiA is essential for the survival of L. pneumophila in the lung. Here we report the first atomic resolution insight into the pathogenic mechanism of a bacterial chitinase. We derive an experimental model of intact ChiA and show how its N-terminal region targets ChiA to the bacterial surface after its secretion. We provide the first evidence that L. pneumophila can bind mucins on its surface, but this is not dependent on ChiA. This demonstrates that additional peripheral mucin binding proteins are also expressed in L. pneumophila. We also show that the ChiA C-terminal chitinase domain has novel Zn2+-dependent peptidase activity against mammalian mucin-like proteins, namely MUC5AC and the C1-esterase inhibitor, and that ChiA promotes bacterial penetration of mucin gels. Our findings suggest that ChiA can facilitate passage of L. pneumophila through the alveolar mucosa, can modulate the host complement system and that ChiA may be a promising target for vaccine development.


Assuntos
Quitinases/metabolismo , Legionella pneumophila/metabolismo , Acetilglucosamina/metabolismo , Proteínas de Bactérias/metabolismo , Quitina/metabolismo , Quitinases/fisiologia , Regulação Bacteriana da Expressão Gênica/genética , Doença dos Legionários/metabolismo , Metais , Mucina-1/metabolismo , Mucinas/metabolismo , Proteólise , Relação Estrutura-Atividade , Fatores de Virulência/metabolismo
12.
Proc Natl Acad Sci U S A ; 117(19): 10357-10367, 2020 05 12.
Artigo em Inglês | MEDLINE | ID: mdl-32345720

RESUMO

Cystic fibrosis (CF) is a recessive disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. The most common symptoms include progressive lung disease and chronic digestive conditions. CF is the first human genetic disease to benefit from having five different species of animal models. Despite the phenotypic differences among the animal models and human CF, these models have provided invaluable insight into understanding disease mechanisms at the organ-system level. Here, we identify a member of the ABCC4 family, CG5789, that has the structural and functional properties expected for encoding the Drosophila equivalent of human CFTR, and thus refer to it as Drosophila CFTR (Dmel\CFTR). We show that knockdown of Dmel\CFTR in the adult intestine disrupts osmotic homeostasis and displays CF-like phenotypes that lead to intestinal stem cell hyperplasia. We also show that expression of wild-type human CFTR, but not mutant variants of CFTR that prevent plasma membrane expression, rescues the mutant phenotypes of Dmel\CFTR Furthermore, we performed RNA sequencing (RNA-Seq)-based transcriptomic analysis using Dmel\CFTR fly intestine and identified a mucin gene, Muc68D, which is required for proper intestinal barrier protection. Altogether, our findings suggest that Drosophila can be a powerful model organism for studying CF pathophysiology.


Assuntos
Regulador de Condutância Transmembrana em Fibrose Cística/metabolismo , Fibrose Cística/patologia , Modelos Animais de Doenças , Proteínas de Drosophila/metabolismo , Intestinos/patologia , Mutação , Células-Tronco/patologia , Animais , Fibrose Cística/genética , Fibrose Cística/metabolismo , Regulador de Condutância Transmembrana em Fibrose Cística/genética , Proteínas de Drosophila/genética , Drosophila melanogaster , Sequenciamento de Nucleotídeos em Larga Escala , Homeostase , Humanos , Mucinas/genética , Mucinas/metabolismo , Fenótipo , Células-Tronco/metabolismo
13.
PLoS One ; 15(4): e0231423, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32302323

RESUMO

Recent advances in canine intestinal organoids have expanded the option for building a better in vitro model to investigate translational science of intestinal physiology and pathology between humans and animals. However, the three-dimensional geometry and the enclosed lumen of canine intestinal organoids considerably hinder the access to the apical side of epithelium for investigating the nutrient and drug absorption, host-microbiome crosstalk, and pharmaceutical toxicity testing. Thus, the creation of a polarized epithelial interface accessible from apical or basolateral side is critical. Here, we demonstrated the generation of an intestinal epithelial monolayer using canine biopsy-derived colonic organoids (colonoids). We optimized the culture condition to form an intact monolayer of the canine colonic epithelium on a nanoporous membrane insert using the canine colonoids over 14 days. Transmission and scanning electron microscopy revealed a physiological brush border interface covered by the microvilli with glycocalyx, as well as the presence of mucin granules, tight junctions, and desmosomes. The population of stem cells as well as differentiated lineage-dependent epithelial cells were verified by immunofluorescence staining and RNA in situ hybridization. The polarized expression of P-glycoprotein efflux pump was confirmed at the apical membrane. Also, the epithelial monolayer formed tight- and adherence-junctional barrier within 4 days, where the transepithelial electrical resistance and apparent permeability were inversely correlated. Hence, we verified the stable creation, maintenance, differentiation, and physiological function of a canine intestinal epithelial barrier, which can be useful for pharmaceutical and biomedical researches.


Assuntos
Colo/citologia , Células Epiteliais/metabolismo , Subfamília B de Transportador de Cassetes de Ligação de ATP/metabolismo , Animais , Diferenciação Celular , Linhagem da Célula , Células Cultivadas , Desmossomos/metabolismo , Cães , Células Epiteliais/citologia , Células Epiteliais/ultraestrutura , Membranas Artificiais , Microvilosidades/fisiologia , Mucinas/metabolismo , Nanoporos , Células-Tronco/citologia , Células-Tronco/metabolismo , Junções Íntimas/metabolismo
14.
PLoS One ; 15(4): e0231990, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32320453

RESUMO

Environmental mold (fungus) exposure poses a significant threat to public health by causing illnesses ranging from invasive fungal diseases in immune compromised individuals to allergic hypertensive diseases such as asthma and asthma exacerbation in otherwise healthy people. However, the molecular pathogenesis has not been completely understood, and treatment options are limited. Due to its thermo-tolerance to the normal human body temperature, Aspergillus. fumigatus (A.fumigatus) is one of the most important human pathogens to cause different lung fungal diseases including fungal asthma. Airway obstruction and hyperresponsiveness caused by mucus overproduction are the hallmarks of many A.fumigatus induced lung diseases. To understand the underlying molecular mechanism, we have utilized a well-established A.fumigatus extracts (AFE) model to elucidate downstream signal pathways that mediate A.fumigatus induced mucin production in airway epithelial cells. AFE was found to stimulate time- and dose-dependent increase of major airway mucin gene expression (MUC5AC and MUC5B) partly via the elevation of their promoter activities. We also demonstrated that EGFR was required but not sufficient for AFE-induced mucin expression, filling the paradoxical gap from a previous study using the same model. Furthermore, we showed that fungal proteases in AFE were responsible for mucin induction by activating a Ras/Raf1/ERK signaling pathway. Ca2+ signaling, but ROS, both of which were stimulated by fungal proteases, was an indispensable determinant for ERK activation and mucin induction. The discovery of this novel pathway likely contributes to our understanding of the pathogenesis of fungal sensitization in allergic diseases such as fungal asthma.


Assuntos
Aspergillus fumigatus/enzimologia , Proteínas Fúngicas/toxicidade , Interações Hospedeiro-Patógeno/fisiologia , Mucinas/metabolismo , Peptídeo Hidrolases/toxicidade , Aspergillus fumigatus/patogenicidade , Cálcio/metabolismo , Linhagem Celular , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Receptores ErbB/metabolismo , Humanos , Pulmão/citologia , Sistema de Sinalização das MAP Quinases , Mucina-5AC/genética , Mucina-5AC/metabolismo , Mucina-5B/genética , Mucina-5B/metabolismo , Mucinas/genética , Proteínas Proto-Oncogênicas c-raf/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Proteínas ras/metabolismo
15.
J Dairy Sci ; 103(7): 6250-6257, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32331876

RESUMO

The use of alternative sources of protein to substitute for milk proteins in milk replacers (MR) can increase the synthesis of endogenous proteins and therefore alter ileal or total-tract digestibility calculations. Mucin is the main component of gastrointestinal mucus and represents the greatest contribution to total endogenous protein. Mucin is difficult to isolate and has not been extensively studied in dairy calves. We explored 3 different procedures to analyze and estimate mucin protein (MUP) in ileal digesta of young dairy calves. Ileal digesta samples were collected from nine 30-d-old ileal-cannulated calves that were enrolled in a 3 × 3 replicated Latin square with 5-d periods. The 3 diets were a control whey protein-based MR (WPC), an isonitrogenous MR in which 50% of the protein was from enzyme-treated soybean meal (ESBM), and an N-free MR (NFREE). Mucin protein concentration and flow were analyzed by fractionation of the digesta and ethanol precipitation; this process served as the reference method. Alternative methods to estimate MUP consisted of using commercial enzymatic kits to analyze glucosamine (N-acetylglucosamine, GlcNAc) and galactosamine (N-acetylgalactosamine, GalNAc), 2 amino-sugars that are highly enriched in mucin. Before GlcNAc determination, samples were processed using 3 different procedures: sample clarification (GLCL), clarification plus hydrolysis (GLCH), and hydrolysis alone (GLHL). The MUP was estimated by regression of the GlcNAc and GalNAc values using previously validated equations. According with the bias and agreement analysis, none of the methods yielded MUP values similar to the reference method. However, GLHL showed a strong association with the reference method (ρ = 0.73). It allowed identifying the smaller MUP flows with NFREE compared with the other 2 diets and detecting the greater flow of ESBM than WPC, as observed with the reference method. Using the GlcNAc values from GLHL and the MUP measured with the reference method, we were able to establish a linear relationship between both methods (adjusted R2 = 0.75). We found that the GLHL method enabled detecting differences in MUP ileal flows between diets differing in protein level and source. Inferences about MUP secretions must be done cautiously because many dietary and physiological factors are involved. The adoption of practical techniques to determine MUP can help to increase our knowledge about gastrointestinal tract function and to improve the accuracy of MR digestibility calculations.


Assuntos
Bovinos , Conteúdo Gastrointestinal/química , Íleo/fisiologia , Mucinas/química , Aminoácidos/metabolismo , Ração Animal/análise , Animais , Animais Lactentes , Dieta/veterinária , Digestão/fisiologia , Masculino , Leite/química , Mucinas/metabolismo , Proteínas/metabolismo , Soja/metabolismo
16.
Int J Pharm ; 577: 119095, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-32004680

RESUMO

The objective of the study was to assess the effect of enhanced mucoadhesion of a cationic mucoadhesive nanostructured lipid carrier (NLC) on its ocular disposition after topical administration. The NLC was made mucoadhesive by surface coating with chitosan oligosaccharide (COS), a low molecular weight derivate of chitosan which is more suitable for drug delivery applications as compared to the native chitosan. The NLC was characterised by surface evaluating techniques like SANS and XPS for confirming coating of COS over the surface of NLC. In order to assess the effect of COS coating on in vivo ocular mucoadhesion, coumarin loaded NLC were topically administered to rats and the sagittal sections of the eyes were imaged using confocal microscopy. The COS coated NLC were seen to adhere more around the ocular surface than the uncoated NLC during the 4-h study. The improved ocular retention for COS-NLC reflected on the content of Etoposide within the eye, which showed a higher concentration of Etoposide, as compared to the uncoated NLC. The NLC was also assessed for any ocular irritancy in rabbits and repeat dose toxicity in rats and found to be relatively non-irritant and non-toxic as compared to appropriate controls. Thus, the study asserts that to achieve higher concentration of therapeutics within the eye, the formulations like NLC are not just required to be permeating but also retentive on the surface of the eye to achieve appreciable concentrations.


Assuntos
Quitosana/química , Sistemas de Liberação de Medicamentos , Etoposídeo/administração & dosagem , Nanoestruturas , Administração Tópica , Animais , Antineoplásicos Fitogênicos/administração & dosagem , Antineoplásicos Fitogênicos/farmacocinética , Cumarínicos/química , Portadores de Fármacos/química , Etoposídeo/farmacocinética , Olho/metabolismo , Lipídeos/química , Mucinas/metabolismo , Oligossacarídeos/química , Coelhos , Ratos , Ratos Sprague-Dawley , Distribuição Tecidual , Testes de Toxicidade
17.
Pediatr Pulmonol ; 55(4): 1061-1073, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32084305

RESUMO

Acute respiratory infections are amongst the leading causes of childhood morbidity and mortality globally. Viruses are the predominant cause of such infections, but mixed etiologies with bacteria has for decades raised the question of the interplay between them in causality and determination of the outcome of such infections. In this review, we examine recent microbiological, biochemical, and immunological advances that contribute to elucidating the mechanisms by which infections by specific viruses enable bacterial infections in the airway, and exacerbate them. We analyze specific domains in which viruses play such facilitating role including enhancement of bacterial adhesion by unmasking cryptic receptors and upregulation of adhesion proteins, disruption of tight junction integrity favoring paracellular transmigration of bacteria and loss of epithelial barrier integrity, increased availability of nutrient, such as mucins and iron, alteration of innate and adaptive immune responses, and disabling defense against bacteria, and lastly, changes in airway microbiome that render the lung more vulnerable to pathogens. Separate exhaustive analysis of each domain focuses on individuals with cystic fibrosis (CF), in whom viruses may play a key role in paving the way for the primary injury that leads to permanence of bacterial pathogens, viruses may then serve as triggers for "CF exacerbations"; these constituting the signature and ultimately the outcome determinants of these patients.


Assuntos
Infecções Respiratórias/microbiologia , Superinfecção/microbiologia , Bactérias , Infecções Bacterianas , Criança , Fibrose Cística/microbiologia , Humanos , Pulmão/metabolismo , Microbiota , Mucinas/metabolismo , Superinfecção/complicações , Vírus/metabolismo
18.
J Med Chem ; 63(10): 5074-5088, 2020 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-32027502

RESUMO

Membrane-bound mucins belong to a heterogeneous family of large O-glycoproteins involved in numerous cancers and inflammatory diseases of the epithelium. Some of them are also involved in protein-protein interactions, with receptor tyrosine kinase ErbB2, and fundamental and clinical data showed that these complexes have a detrimental impact on cancer outcome, thus raising interest in therapeutic targeting. This paper aims to demonstrate that MUC3, MUC4, MUC12, MUC13, and MUC17 have a common evolutionary origin and share a common structural organization with EGF-like and SEA domains. Theoretical structure-function relationship analysis of the conserved domains indicated that the studied membrane-bound mucins share common biological properties along with potential specific functions. Finally, the potential druggability of these complexes is discussed, revealing ErbB2-related pathways of cell signaling to be targeted.


Assuntos
Membrana Celular/metabolismo , Sistemas de Liberação de Medicamentos/tendências , Fator de Crescimento Epidérmico/metabolismo , Mucinas/metabolismo , Receptor ErbB-2/metabolismo , Transdução de Sinais/efeitos dos fármacos , Sequência de Aminoácidos , Animais , Antineoplásicos/administração & dosagem , Antineoplásicos/metabolismo , Membrana Celular/efeitos dos fármacos , Sistemas de Liberação de Medicamentos/métodos , Fator de Crescimento Epidérmico/antagonistas & inibidores , Fator de Crescimento Epidérmico/química , Humanos , Mucinas/antagonistas & inibidores , Mucinas/química , Estrutura Secundária de Proteína , Receptor ErbB-2/antagonistas & inibidores , Receptor ErbB-2/química , Transdução de Sinais/fisiologia
19.
Sci Rep ; 10(1): 960, 2020 01 22.
Artigo em Inglês | MEDLINE | ID: mdl-31969624

RESUMO

Vancomycin, a branched tricyclic glycosylated peptide antibiotic, is a last-line defence against serious infections caused by staphylococci, enterococci and other Gram-positive bacteria. Orally-administered vancomycin is the drug of choice to treat pseudomembranous enterocolitis in the gastrointestinal tract. However, the risk of vancomycin-resistant enterococcal infection or colonization is significantly associated with oral vancomycin. Using the powerful matrix-free assay of co-sedimentation analytical ultracentrifugation, reinforced by dynamic light scattering and environmental scanning electron microscopy, and with porcine mucin as the model mucin system, this is the first study to demonstrate strong interactions between vancomycin and gastric and intestinal mucins, resulting in very large aggregates and depletion of macromolecular mucin and occurring at concentrations relevant to oral dosing. In the case of another mucin which has a much lower degree of glycosylation (~60%) - bovine submaxillary mucin - a weaker but still demonstrable interaction is observed. Our demonstration - for the first time - of complexation/depletion interactions for model mucin systems with vancomycin provides the basis for further study on the implications of complexation on glycopeptide transit in humans, antibiotic bioavailability for target inhibition, in situ generation of resistance and future development strategies for absorption of the antibiotic across the mucus barrier.


Assuntos
Antibacterianos/farmacologia , Trato Gastrointestinal/efeitos dos fármacos , Mucinas/metabolismo , Agregados Proteicos/efeitos dos fármacos , Vancomicina/farmacologia , Animais , Bovinos , Trato Gastrointestinal/metabolismo , Ligação Proteica/efeitos dos fármacos , Suínos
20.
Int J Mol Sci ; 21(3)2020 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-31979419

RESUMO

The TFF peptides xP1 and xP4 from Xenopus laevis are orthologs of TFF1 and TFF2, respectively. xP1 is secreted as a monomer from gastric surface mucous cells and is generally not associated with mucins, whereas xP4 is a typical secretory peptide from esophageal goblet cells, and gastric mucous neck and antral gland cells tightly associated as a lectin with the ortholog of mucin MUC6. Both TFF peptides have diverse protective functions, xP1 as a scavenger for reactive oxygen species preventing oxidative damage and xP4 as a constituent of the water-insoluble adherent inner mucus barrier. Here, we present localization studies using immunofluorescence and immunoelectron microscopy. xP1 is concentrated in dense cores of secretory granules of surface mucous cells, whereas xP4 mixes with MUC6 in esophageal goblet cells. Of note, we observe two different types of goblet cells, which differ in their xP4 synthesis, and this is even visible morphologically at the electron microscopic level. xP4-negative granules are recognized by their halo, which is probably the result of shrinkage during the processing of samples for electron microscopy. Probably, the tight lectin binding of xP4 and MUC6 creates a crosslinked mucous network forming a stabile granule matrix, which prevents shrinkage.


Assuntos
Mucosa Esofágica/metabolismo , Mucosa Gástrica/metabolismo , Células Caliciformes/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Vesículas Secretórias/metabolismo , Proteínas de Xenopus/metabolismo , Animais , Secreções Corporais/metabolismo , Mucosa Esofágica/ultraestrutura , Esôfago/metabolismo , Esôfago/ultraestrutura , Imunofluorescência , Mucosa Gástrica/ultraestrutura , Células Caliciformes/citologia , Células Caliciformes/ultraestrutura , Lectinas/metabolismo , Microscopia Eletrônica , Mucina-6/metabolismo , Mucinas/metabolismo , Proteínas de Xenopus/ultraestrutura , Xenopus laevis
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