Clostridium difficile toxin B inhibits the secretory response of human mast cell line-1 (HMC-1) cells stimulated with high free-Ca2+ and GTPγS. (3rd February 2015)

• Record Type: Journal Article
• Authors: Balletta, Andrea; Lorenz, Dorothea; Rummel, Andreas; Gerhard, Ralf; Bigalke, Hans; Wegner, Florian
• Is Part Of: Toxicology. Volume 328(2015)
• Page Start: 48
• Page End: 56
• Publication Date: 2015-02-03
• Subjects: Human mast cell line-1 (HMC-1) -- Membrane capacitance -- Whole-cell patch-clamp -- GTPγS -- Clostridium difficile toxin B (TcdB) -- Hexosaminidase; Toxicology -- Periodicals; Chemicals -- Physiological effect -- Periodicals; 615.9005
• DOI: 10.1016/j.tox.2014.12.006
• Languages: English
• ISSNs: 0300-483X

Abstract

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 3–24 h 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.