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Clostridium difficile toxin A stimulates macrophage-inflammatory protein-2 production in rat intestinal epithelial
I Castagliuolo1, A C Keates, C C Wang
1Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
Abstract:
Neutrophil infiltration of the colonic mucosa is a hallmark of Clostridium difficile toxin A-mediated enterocolitis. Macrophage-inflammatory protein-2 (MIP-2) is a potent neutrophil chemoattractant secreted by rat macrophages and epithelial cells in response to inflammatory stimuli. In this work, we report that administration of toxin A into rat ileal loops increased mucosal levels of MIP-2 before the onset of fluid secretion and mucosal neutrophil infiltration. Administration of rabbit anti-MIP-2 IgG, but not control IgG, reduced toxin A-mediated secretion (by 58%), mucosal permeability (by 80%), and myeloperoxidase activity (by 85%). Immunohistochemical analysis demonstrated increased MIP-2 expression in intestinal epithelial and lamina propria cells 1 h after toxin A administration. Intestinal epithelial cells purified from toxin A-exposed ileal loops also showed increased MIP-2 mRNA expression and MIP-2 protein release that was inhibited by pretreatment of rats with the transcriptional inhibitor actinomycin D. These results indicate that C. difficile toxin A induces MIP-2 release from intestinal epithelial cells and that MIP-2 contributes to neutrophil mucosal influx during toxin A enteritis.
Insights
Clostridium difficile toxin A triggers intestinal inflammation by increasing macrophage-inflammatory protein-2 (MIP-2). Blocking MIP-2 significantly reduced toxin A-induced enterocolitis symptoms in rats.
Area of Science:
- Gastroenterology
- Immunology
- Microbiology
Background:
- Neutrophil infiltration is key in Clostridium difficile toxin A-induced enterocolitis.
- Macrophage-inflammatory protein-2 (MIP-2) is a neutrophil chemoattractant involved in inflammation.
Purpose of the Study:
- To investigate the role of MIP-2 in C. difficile toxin A enteritis.
- To determine if MIP-2 mediates neutrophil influx and intestinal damage.
Main Methods:
- Administration of toxin A into rat ileal loops.
- Measurement of MIP-2 levels, fluid secretion, mucosal permeability, and myeloperoxidase activity.
- Inhibition of MIP-2 using anti-MIP-2 IgG.
- Immunohistochemistry and mRNA analysis for MIP-2 expression.
Main Results:
- Toxin A increased mucosal MIP-2 levels prior to fluid secretion and neutrophil infiltration.
- Anti-MIP-2 IgG significantly reduced toxin A-induced secretion, permeability, and myeloperoxidase activity.
- Toxin A exposure led to increased MIP-2 expression in intestinal epithelial and lamina propria cells.
- Transcriptional inhibition blocked toxin A-induced MIP-2 mRNA expression and protein release.
Conclusions:
- C. difficile toxin A induces MIP-2 release from intestinal epithelial cells.
- MIP-2 plays a critical role in mediating neutrophil influx during toxin A enteritis.
- Targeting MIP-2 may be a therapeutic strategy for C. difficile infections.