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 diffici le, toxins, A and B in the pathogenesis of antibiotic-associated diarrhea. Recently, we demonstrated that IL-I 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 rabbi t ileal ion transport. The changes in ion transport were analyzed by studyi ng the short-circuit current of the rabbit ileal mucosa mounted in Ussing c hambers. 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 (De lta I-sc)=28.0+/-9.2 vs, control = 26.8+/-,3.6 mu A cm(-2)). Supernatants o f macrophages stimulated with toxin A (3.2 x 10(-7) M), our positive contro l, 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 stimula ted macrophages to produce TNF-alpha (555.0 +/- 37.9 pg/ml vs. control = 18 2.0+/-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 s timulated with toxin B are not able to stimulate ion transport and that bot h toxins stimulate the genesis of TNF-alpha, but only toxin A induces the s ynthesis of IL-1 beta, which, we have earlier reported, causes an electroge nic intestinal response in rabbit ileum. (C) 2000 Elsevier Science Ltd. All rights reserved.