RESUMEN
Surface modifications in the nanoscale regime have shown promising potential in the combat against bacterial adhesion and colonization of surfaces. However, detailed knowledge of how the bacteria-substrate interactions occur is still limited. Herein we have used a gradient in nanostructure density on a surface, realized by immobilizing 40 nm sized silicon dioxide nanoparticles with increasing distance on a glass surface, to systematically study the initial attachment of Staphylococcus epidermidis with or without the presence of human fibrinogen. By using a parallel plate laminar flow chamber, we found a near-linear positive correlation between the adhesion of S. epidermidis with increasing nanoparticle density on unmodified (hydrophilic) nanogradients as well as on gradients where polyethylene glycol was immobilized on the surface in-between nanoparticles. However, if the nanostructured gradient was precoated with human fibrinogen the opposite relationship was observed, although the adsorbed amount of fibrinogen was found to be higher on nanostructured than on smooth surfaces. Our results highlight that even minute changes of the nanotopography on a surface can have profound impact on initial attachment of S. epidermidis to biomaterial surfaces and that the presence of nanostructures strongly hampered the cell's ability to bind to adsorbed fibrinogen, possibly due to changes in the orientation or secondary structure of the fibrinogen molecule upon adsorption.
RESUMEN
Interference with bacterial quorum sensing communication provides an anti-virulence strategy to control pathogenic bacteria. Here, using the Enteropathogenic E. coli (EPEC) O103:H2, we showed for the first time that thiophenone TF101 reduced expression of lsrB; the gene encoding the AI-2 receptor. Combined results of transcriptional and phenotypic analyses suggested that TF101 interfere with AI-2 signalling, possibly by competing with AI-2 for binding to LsrB. This is supported by in silico docking prediction of thiophenone TF101 in the LsrB pocket. Transcriptional analyses furthermore showed that thiophenone TF101 interfered with expression of the virulence genes eae and fimH. In addition, TF101 reduced AI-2 induced E. coli adhesion to colorectal adenocarcinoma cells. TF101, on the other hand, did not affect epinephrine or norepinephrine enhanced E. coli adhesion. Overall, our results showed that thiophenone TF101 interfered with virulence expression in E. coli O103:H2, suggestedly by interfering with AI-2 mediated quorum sensing. We thus conclude that thiophenone TF101 might represent a promising future anti-virulence agent in the fight against pathogenic E. coli.
Asunto(s)
Antibacterianos/farmacología , Escherichia coli Enteropatógena/efectos de los fármacos , Escherichia coli Enteropatógena/patogenicidad , Regulación Bacteriana de la Expresión Génica , Homoserina/análogos & derivados , Lactonas/antagonistas & inhibidores , Tiofenos/farmacología , Adhesinas Bacterianas/química , Adhesinas Bacterianas/genética , Adhesinas Bacterianas/metabolismo , Adhesinas de Escherichia coli/química , Adhesinas de Escherichia coli/genética , Adhesinas de Escherichia coli/metabolismo , Antibacterianos/química , Adhesión Bacteriana/efectos de los fármacos , Sitios de Unión , Proteínas Portadoras/antagonistas & inhibidores , Proteínas Portadoras/química , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Línea Celular Tumoral , Escherichia coli Enteropatógena/genética , Escherichia coli Enteropatógena/crecimiento & desarrollo , Epinefrina/farmacología , Proteínas de Escherichia coli/antagonistas & inhibidores , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Proteínas Fimbrias/química , Proteínas Fimbrias/genética , Proteínas Fimbrias/metabolismo , Homoserina/antagonistas & inhibidores , Homoserina/metabolismo , Humanos , Lactonas/metabolismo , Simulación del Acoplamiento Molecular , Norepinefrina/farmacología , Unión Proteica , Percepción de Quorum/efectos de los fármacos , Receptores de Superficie Celular/antagonistas & inhibidores , Receptores de Superficie Celular/química , Receptores de Superficie Celular/genética , Receptores de Superficie Celular/metabolismo , Transducción de Señal , Tiofenos/química , VirulenciaRESUMEN
BACKGROUND: Carriage of and infection with Streptococcus pneumoniae is known to predominantly induce T helper 17 (Th17) responses in humans, but the types of Th cells showing reactivity towards commensal streptococci with low pathogenic potential, such as the oral commensals S. mitis and S. salivarius, remain uncharacterized. METHODS: Memory CD4(+) T helper (Th) cell subsets were isolated from healthy human blood donors according to differential expression of chemokine receptors, expanded in vitro using polyclonal stimuli and characterized for reactivity against different streptococcal strains. RESULTS: Th cells responding to S. mitis, S. salivarius and S. pneumoniae were predominantly in a CCR6(+)CXCR3(+) subset and produced IFN-γ, and in a CCR6(+)CCR4(+) subset and produced IL-17 and IL-22. Frequencies of S. pneumoniae-reactive Th cells were higher than frequencies of S. mitis- and S. salivarius-specific Th cells. S. mitis and S. pneumoniae isogenic capsule knock-out mutants and a S. mitis mutant expressing the serotype 4 capsule of S. pneumoniae showed no different Th cell responses as compared to wild type strains. S. mitis-specific Th17 cells showed cross-reactivity with S. pneumoniae. CONCLUSIONS: As Th17 cells partly control clearance of S. pneumoniae, cross-reactive Th17 cells that may be induced by commensal bacterial species may influence the immune response, independent of capsule expression.
