Abstract
The pathophysiology of Clostridium difficile colitis is thought to be mediated by release of toxin A, an enterotoxin, and toxin B, a cytotoxin. We compared the differential effects of toxin B on protein synthesis in IMR-90 fibroblasts and in hamster esophagus, stomach, gallbladder, small intestine, and cecum in organ culture. Toxin B in low concentrations stimulated (p less than 0.001) incorporation of [3H]leucine into fibroblast proteins, whereas at higher dosages it inhibited incorporation (p less than 0.001). This biphasic effect was independent of cell rounding and was not caused by a change in uptake of precursor. Purified toxin B had no effect on protein synthesis in a cell-free rabbit reticulocyte translation system, indicating that inhibition of protein synthesis in intact fibroblast monolayers and intestinal explants is a consequence of toxin B effect on some other cellular target. Toxin B significantly inhibited protein synthesis in hamster cecal explants in a dose-dependent fashion. Again, this inhibition was not mediated by altered precursor uptake. Toxin B significantly inhibited in vitro protein synthesis in hamster terminal ileum, cecum, and sigmoid colon, but not in esophagus, gallbladder, stomach, or duodenum. These results suggest that toxin B-mediated inhibition of protein synthesis may be a generalized toxic effect in tissue culture cells and intestinal epithelium. Inhibition of protein synthesis in the distal intestinal epithelium may contribute to the pathophysiology of colitis caused by this organism.
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