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

Abstract

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-1β 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 Üssing chambers. The supernatants of macrophages treated with toxin B (3.6×10 −7 M) had no effect on the ion transport (change in short-circuit current ΔI sc =28.0±9.2 vs. control=26.8±3.6 μA cm −2). Supernatants of macrophages stimulated with toxin A (3.2×10 −7 M), our positive control, induced a significant change in ileal ion transport (Δ I sc=55.2±5.7 mA cm −2). It was also observed that, like toxin A, toxin B stimulated macrophages to produce TNF-α (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-1β 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-α, but only toxin A induces the synthesis of IL-1β, which, we have earlier reported, causes an electrogenic intestinal response in rabbit ileum.