Clostridium difficile toxin B inhibits the secretory response of human mast cell line-1 (HMC-1) cells stimulated with high free-Ca²âº and GTPγS.
Toxicology
; 328: 48-56, 2015 Feb 03.
Article
em En
| MEDLINE
| ID: mdl-25497110
ABSTRACT
Clostridium difficile toxins A and B (TcdA and TcdB) belong to the class of large clostridial cytotoxins and inactivate by glucosylation some low molecular mass GTPases of the Rho-family (predominantly Rho, Rac and Cdc42), known as regulators of the actin cytoskeleton. TcdA and B also represent the main virulence factors of the anaerobic gram-positive bacterium that is the causal agent of pseudomembranous colitis. In our study, TcdB was chosen instead of TcdA for the well-known higher cytotoxic potency. Inactivation of Rho-family GTPases by this toxin in our experimental conditions induced morphological changes and reduction of electron-dense mast cell-specific granules in human mast cell line-1 (HMC-1) cells, but not cell death or permeabilisation of plasma-membranes. Previously reported patch-clamp dialysis experiments revealed that high intracellular free-Ca(2+) and GTPγS concentrations are capable of inducing exocytosis as indicated by significant membrane capacitance (Cm) increases in HMC-1 cells. In this study, we investigated the direct effects of TcdB upon HMC-1 cell "stimulated" Cm increase, as well as on "constitutive" secretion of hexosaminidase and interleukin-16 (IL-16). Compared to untreated control cells, HMC-1 cells incubated with TcdB for 3-24h exhibited a significant reduction of the mean absolute and relative Cm increase in response to free-Ca(2+) and GTPγS suggesting an inhibition of secretory processes by TcdB. In conclusion, the HMC-1 cell line represents a suitable model for the study of direct effects of C. difficile toxins on human mast cell secretory activity.
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Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
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Toxinas Bacterianas
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Cálcio
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Guanosina 5'-O-(3-Tiotrifosfato)
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Interleucina-16
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Exocitose
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Hexosaminidases
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Mastócitos
Tipo de estudo:
Prognostic_studies
Limite:
Humans
Idioma:
En
Revista:
Toxicology
Ano de publicação:
2015
Tipo de documento:
Article