Absence of intestinal secretion on supernatants from macrophages stimulated with Clostridium difficile toxin B on rabbit ileum.

Several studies have documented the involvement of both Clostridium difficile, toxins, A and B in the pathogenesis of antibiotic-associated diarrhea. Recently, we demonstrated that IL-1 beta is the intestinal secretory factor released by macrophages stimulated with toxin A. The aim of this study was to evaluate the importance of macrophages stimulated with toxin B on rabbit ileal ion transport. The changes in ion transport were analyzed by studying the short-circuit current of the rabbit ileal mucosa mounted in Ussing chambers. The supernatants of macrophages treated with toxin B (3.6 x 10(-7) M) had no effect on the ion transport (change in short-circuit current =28.0+/-9.2 vs. control=26.8+/-3.6 microA cm(-2)). Supernatants of macrophages stimulated with toxin A (3.2 x 10(-7) M), our positive control, induced a significant change in ileal ion transport (delta I(sc)=55.2+/-5.7 mA cm(-2)). It was also observed that, like toxin A, toxin B stimulated macrophages to produce TNF-alpha (555.0+/-37.9 pg/ml vs. control=182.0+/-39.8 pg/ml; p<0.05). Nevertheless, in contrast to toxin A, toxin B did not stimulate IL-1 beta synthesis (28.0+/-7.5 pg/ml vs. control=40. 0+/-14.4 pg/ml; p>0.05). We conclude that the supernatants of macrophages stimulated with toxin B are not able to stimulate ion transport and that both toxins stimulate the genesis of TNF-alpha, but only toxin A induces the synthesis of IL-1 beta, which, we have earlier reported, causes an electrogenic intestinal response in rabbit ileum.