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1.
Immune Network ; : 213-217, 2013.
Artículo en Inglés | WPRIM | ID: wpr-223721

RESUMEN

Enterotoxigenic Bacteroides fragilis (ETBF) is a human gut commensal bacteria that causes inflammatory diarrhea and colitis. ETBF also promotes colorectal tumorigenesis in the Min mouse model. The key virulence factor is a secreted metalloprotease called B. fragilis toxin (BFT). BFT induces E-cadherin cleavage, cell rounding, activation of the beta-catenin pathway and secretion of IL-8 in colonic epithelial cells. However, the precise mechanism by which these processes occur and how these processes are interrelated is still unclear. E-cadherin form homophilic interactions which tethers adjacent cells. Loss of E-cadherin results in detachment of adjacent cells. Prior studies have suggested that BFT induces IL-8 expression by inducing E-cadherin cleavage; cells that do not express E-cadherin do not secrete IL-8 in response to BFT. In the current study, we found that HT29/C1cells treated with dilute trypsin solution induced E-cadherin degradation and IL-8 secretion, consistent with the hypothesis that E-cadherin cleavage causes IL-8 secretion. However, physical damage to the cell monolayer did not induce IL-8 secretion. We also show that EDTA-mediated disruption of E-cadherin interactions without E-cadherin degradation was sufficient to induce IL-8 secretion. Finally, we determined that HT29/C1 cells treated with LiCl (beta-catenin activator) induced IL-8 secretion in a dose-dependent and time-dependent manner. Taken together, our results suggest that BFT induced IL-8 secretion may occur by the following process: E-cadherin cleavage, disruption of cellular interactions, activation of the beta-catenin pathway and IL-8 expression. However, we further propose that E-cadherin cleavage per se may not be required for BFT induced IL-8 secretion.


Asunto(s)
Animales , Humanos , Ratones , Bacterias , Toxinas Bacterianas , Bacteroides fragilis , Bacteroides , beta Catenina , Cadherinas , Transformación Celular Neoplásica , Colitis , Colon , Diarrea , Ácido Edético , Células Epiteliales , Fibrinógeno , Interleucina-8 , Metaloendopeptidasas , Tripsina
2.
Mem. Inst. Oswaldo Cruz ; 103(7): 734-735, Nov. 2008. tab
Artículo en Inglés | LILACS | ID: lil-498385

RESUMEN

The presence of enterotoxigenic Bacteroides fragilis and nontoxigenic B. fragilis (NTBF) among 109 strains isolated from 1980-2008 in Brazil were investigated by PCR. One strain, representing 0.9 percent of the total analyzed strains, harbored the bft gene which was identified as bft-1 isoform based on PCR-RFLP and sequencing. Forty-nine strains (44.9 percent) exhibited the NTBF pattern III which possesses the flanking region required for pathogenicity island acquisition in which the bftgene is codified. These data reinforce the potential of B. fragilis as an emerging enteropathogen in our country.


Asunto(s)
Humanos , Bacteroides fragilis/genética , Enterotoxinas/biosíntesis , Genes Bacterianos/genética , Brasil , Bacteroides fragilis/clasificación , Bacteroides fragilis/patogenicidad , Reacción en Cadena de la Polimerasa , Polimorfismo de Longitud del Fragmento de Restricción
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