Helicobacter pylori adhesion to gastric epithelial cells is mediated by glycan receptors

Helicobacter pylori adhesion to gastric epithelial cells constitutes a key step in the establishment of a successful infection of the gastric mucosa. The high representation of outer membrane proteins in the bacterial genome suggests the relevance of those proteins in the establishment of profitable interactions with the host gastric cells. Gastric epithelial cells are protected by a mucous layer gel, mainly consisting of the MUC5AC and MUC6 mucins. In addition to this protective role, mucins harbor glycan-rich domains that constitute preferential binding sites of many pathogens. In this article we review the main players in the process of H. pylori adhesion to gastric epithelial cells, which contribute decisively to the high prevalence and chronicity of H. pylori infection. The BabA adhesin recognizes both H-type 1 and Lewis b blood-group antigens expressed on normal gastric mucosa of secretor individuals, contributing to the initial steps of infection. Upon colonization, persistent infection induces an inflammatory response with concomitant expression of sialylated antigens. The SabA adhesin mediates H. pylori binding to inflamed gastric mucosa by recognizing sialyl-Lewis a and sialyl-Lewis x antigens. The expression of the BabA and SabA adhesins is tightly regulated, permitting the bacteria to rapidly adapt to the changes of glycosylation of the host gastric mucosa that occur during infection, as well as to escape from the inflammatory response. The growing knowledge of the interactions between the bacterial adhesins and the host receptors will contribute to the design of alternative strategies for eradication of the infection.

Arginine and glutamate levels in the gingival crevicular fluid from patients with chronic periodontitis

The objectives of this study were to determine arginine and glutamate levels in the gingival crevicular fluid (GCF) of adult chronic periodontitis patients versus periodontally healthy controls, and to compare two kinds of microdialysis probes: normal and U-shaped probes. The analysis of GCF components was developed to improve the diagnosis of periodontal disease (PD). Proteolysis in the periodontal tissues increases the concentration of amino acids (aa) in the GCF and the levels of these aa may reveal PD features and stages. GCF samples were collected by microdialysis in situ from 5 periodontally affected sites (probing depth >5 mm, clinical attachment loss >3 mm) in 14 adult chronic periodontitis patients and from 14 adult periodontally healthy controls. Capillary zone electrophoresis coupled to laser induced fluorescence detection was used to measure concentration of arginine and glutamate in the GCF. Data were analyzed statistically by ANOVA and Tukey's post-hoc tests (?=0.05). Arginine concentration was increased (p<0.001) and glutamate concentration was decreased (p<0.001) in chronic periodontitis patients as compared to controls. There were no significant differences (p=0.069) between the normal and U-shaped probes. In conclusion, the increase of arginine and decrease of glutamate concentration in GCF were associated to the presence of periodontitis, and might be used as markers to recognize periodontally susceptible subjects as well as to evaluate the treatment course.

Os objetivos deste estudo foram determinar os níveis de arginina e glutamato no fluido gengival crevicular (FGC) em pacientes com periodontite crônica contra controles saudáveis e comparar dois tipos de cânulas de microdiálise: normais e em forma de U. A análise dos componentes do FGC desenvolveu-se para melhorar o diagnóstico da doença periodontal (DP). A proteólise dos tecidos periodontais aumenta a concentração de aminoácidos (aa) no FGC e os níveis destes aa podem revelar as características e estágios da DP. Amostras de FGC foram obtidas pela técnica de microdiálise in situ de cinco zonas com o periodonto afetado (profundidade de sondagem >5 mm, perda da inserção clínica >3 mm) em 14 pacientes adultos com periodontite crônica e 14 controles saudáveis. Para medir a concentração de arginina e glutamato no GFC, usou-se a técnica de eletroforese capilar com detecção de fluorescência induzida por laser. Nos pacientes com periodontite crônica, a concentração de arginina aumentou significantemente (p<0.001), enquanto a de glutamato diminuiu significantemente (p<0.001) em comparação aos controles. Não houve diferenças significantes (p=0.069) entre as cânulas normais e as cânulas em forma de U. Conclui-se que o aumento da concentração de arginina e diminuição de glutamato no FGC estavam associados à presença de periodontite, e podem ser usados como marcadores para identificar pacientes suscetíveis à periodontite bem como avaliar a evolução do tratamento.

Mycobacterium leprae interactions with the host cell: recent advances.

The significance of Hansen disease, or leprosy, is underscored by fact that detection of this disease has remained stable over the past 10 yr, even though disease prevalence is reduced. Due to the long incubation time of the organism, health experts predict that leprosy will be with us for decades to come. Despite the fact that Mycobacterium leprae, the causative agent of leprosy, cannot be cultured in the laboratory, researchers are using innovative and imaginative techniques to discern the interactions of M. leprae with host cells both in vitro and in vivo to identify the host and bacterial factors integral to establishment of disease. The studies described in this review present a new and evolving picture of the many interactions between M. leprae and the host. Specific attention will be given to interactions of M. leprae bacilli with host Schwann cells, macrophages, dendritic cells and endothelial cells. The findings described also have implications for the prevention and treatment of leprosy.

Adhesion of Streptococcus mutans to salivary proteins in caries-free and caries susceptible individuals

La adhesión de los microorganismos a las superficies dentales, es el paso inicial en la formación de la placa dentobacteriana, Streptococcus mutans (S. mutans) es uno de los encontrados en ésta y está asociado como el principal agente causal de una delas enfermedades más comunes en los humanos, la caries dental. La adherencia de esta bacteria se da por la interacción de adhesinas que la constituyen con los componentes salivales, específicamente con los que están formando parte de la película adquirida. La complejidad de esta interacción ha sido motivo deestudio durante los últimos años, hasta el punto de identificar algunos componentes salivales relacionados con la unión a las superficies del esmalte, tales como Proteínas ricas en prolina(PRPs), staterinas,Histatinas,Cistatinas, etc. En el presente trabajo se buscó determinar la capacidad de adhesión de S. mutans a hidroxilapatita sintética incubada con muestras de salivade personas con y sin experiencia de caries. Para estos ensayos se utilizó tanto la muestra de saliva completa como extractos de proteínas salivales, obtenidos por medio de la separaciónde las proteínas contenidas en la muestra por SDS-PAGE, en tres rangos de peso molecular seleccionados de acuerdo con el perfil electroforético que fue comúnmente encontrado. Losresultados indican que la adhesión de este microorganismo es mayor en las personas sin experiencia de caries cuando se ensayó con saliva completa y con las proteínas separadas en el rangode peso molecular de 120-159 kDa. Sugiriendo que la adhesión por sí sola no tiene un efecto determinante en los mecanismos que producen la enfermedad en algunas personas. Sin embargo estos hallazgos son interesantes ya que pueden contribuir en el diseño de estrategias para intervenir en la adhesión de S. mutanssobre las superficies dentales

Adhesion of microorganisms to dental surfaces is the initial step in the formation of dental bacterial plaque. Streptococcus mutans (S. mutans) is considered the main causal agent of one of the most common diseases in humans: dental caries. Adherence of these bacteria results from the interaction of adhesins that form part of their structure with salivary components, specifically those that compose the acquired pellicle. The complexity of this interaction has been the subject of studies in past years, to the extent of identifying certain salivary components related to adhesion to enamel surfaces, such as proline-rich proteins (PRSs), Staherins, Histatins, Cystatins, etc. One of the objectives of this study was to determine the adhesion capacity of S. mutans to synthetic hydroxyapatite incubated with saliva samples of caries-active and caries-inactive individuals. For the purpose of these assays, both the whole saliva samples and the salivary protein extracts were used. They were obtained by separating the proteins contained in the simple SDS-PAGE, in three ranges of molecular weight, selected in accordance with the electrophoresis profile that was usually found. The results indicated that the adhesion of this microorganism was greater in caries-inactive patients, when tested with whole saliva and proteins in the 120-159 kDa molecular weight range. This suggests that adhesion, per se, does not have a definite effect on the mechanisms that cause the disease in some individuals. However, these are interesting findings that may contribute to the design of strategies to control the adhesion of S. mutans to the tooth’s surface.

Adhesion of salivary components to Streptococcus mutans peptides

Streptococcus mutans es el principal microorganismo asociadoa la caries dental, esta bacteria se une al esmalte a través de su interacción con las proteínas de la película adquirida yla proteína de superficie celular comúnmente denominada PAc. Por lo menos dos sitios de PAc interactúan in vitro con los receptores salivales, uno está dentro de la región más conservadade esta proteína que comprende los residuos de 816-1213 y el otro dentro de la secuencia rica en Alanina, residuos186-469. El objetivo del presente trabajo fue establecer similitudes o diferencias en la interacción de péptidos de PAc con los componentes salivales de individuos con y sin experienciade caries, para lo cual se tomaron muestras de saliva por salivación espontánea de 20 individuos con caries y 20 sin caries. A partir de las muestras de saliva se extrajeron las proteínas de la película adquirida (PA) utilizando hidroxilapatita sintética y fueron sometidas a la interacción con trespéptidos sintéticos de los segmentos de unión de PAc con los componentes salivales: PAc (301-319), PAc (365-377) y PAc (1024-1044). Los resultados muestran una baja interacciónentre los componentes de la PA y los péptidos en todos los individuos, sugiriendo que con base en las similitudes entre los individuos sanos y los individuos con la enfermedad lospéptidos de PAc estudiados no son relevantes en la adhesión

Streptococcus mutans is the main microorganism associated to dental caries; it adheres to the dental enamel by interacting with the acquired film’s proteins and the cell surface adhesin, called variously antigen PAc. At least two distinct sites in PAc interact with salivary receptors in vitro, these are within residues 816-1213, the most conserved portion of PAc, and within residues 186-469, the alanine-rich sequence. Our purpose was to establish differences or similarities in PAc’s peptides interactions with the salivary components of individuals with and without previous caries experience. 40 saliva samples were obtained from patients with (n=20) and without (n=20) caries. The acquired film’s proteins were extracted using hydroxyapatite, and subjected to interaction with three synthetic PAc peptides (PAc (301-319), PAc (365-377), and PAc (1025-1044)) synthesized from PAc’s bonding sites to the salivary components. The results show low interaction between the acquired pellicle components and the peptides in all patients. This suggests that the examined PAc’s are not relevant as far as the initial adhesion of Streptococcus mutans to the tooth’s surface is concerned, as defined by the similarities in the results for healthy and affected individuals.

Human immunogenicity studies on group A streptococcal C5a peptidase (SCPA) as a potential vaccine against group A streptococcal infections.

BACKGROUND & OBJECTIVES: Group A streptococcal C5a peptidase (SCPA) is a major virulence surface factor. Its highly conserved nature among all tested serotypes of group A streptococci (GAS) as well as animal protection studies make SCPA a prime vaccine candidate. The present study was undertaken to explore the human immunogenicity to SCPA using an indirect enzyme-linked immunosorbent assay. METHODS: Children (n=72) who had signs and symptoms of acute pharyngitis and had GAS isolated from the throat at initial visit were included. Acute and convalescent sera were collected 4 weeks apart. ELISA was performed using recombinant SCPA peptide as antigen. RESULTS: The mean convalescent anti-SCPA level was twice the level of mean acute anti-SCPA and the difference was statistically significant (P < 0.0001). There was a rise in convalescent anti-SCPA in all children aged 2-12 yr. INTERPRETATION & CONCLUSION: Our observations confirmed that SCPA was highly immunogenic in children infected with group A streptococcal pharyngitis. Further studies need to be done to characterize the immune response including antibody subclass.

Promotion of fibronectin independent invasion by C5a peptidase into epithelial cells in group A Streptococcus.

BACKGROUND & OBJECTIVES: Group A Streptococcus, causative agent of several clinical manifestations codes for multiple protein invasins which help the bacterium to enter non-phagocytic cells. C5a peptidase (SCPA) is a surface protein conserved among different serotypes of M1 strain. The present study was taken up to study SCPA promoted fibronectin independent entry of GAS into epithelial cells. METHODS: An isogenic 90226 emm1deltaAB (M1(-)) mutant was constructed with thermosensitive pGhost vector. This isogenic M1(-) mutant expressed SCPA on the surface as determined by Western blotting and immunofluorescence. RESULTS: On preincubation with anti-SCPA serum, the isogenic M1(-) strain exhibited 54 per cent decreased invasion as compared to the bacteria incubated with control serum. Also, purified recombinant SCPA proteins blocked internalization of M1(-) streptococci into HEp-2 cells. The M1(-) strain invaded at the same efficiency in the presence or absence of fibronectin. INTERPRETATION & CONCLUSION: These results suggested that SCPA acted as a potential invasin of group A streptococcus and promoted invasion independent of fibronectin.