title: 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-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.
authors.affiliation: Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, CE, Brazil.
authors.forename: M F
authors.initials: MF
authors.lastname: Rocha
authors.forename: A M
authors.initials: AM
authors.lastname: Soares
authors.forename: R A
authors.initials: RA
authors.lastname: Ribeiro
authors.forename: A A
authors.initials: AA
authors.lastname: Lima
mesh_terms: D000818:Animals; D001426:Bacterial Proteins; D001427:Bacterial Toxins / Q000494:pharmacology*; D004768:Enterotoxins / Q000494:pharmacology*; D005260:Female; D007082:Ileum / Q000187:drug effects / Q000378:metabolism; D007375:Interleukin-1 / Q000378:metabolism*; D017136:Ion Transport / Q000187:drug effects*; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008297:Male; D011817:Rabbits; D051381:Rats; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004768:Enterotoxins; D007375:Interleukin-1; D014409:Tumor Necrosis Factor-alpha; C041348:tcdA protein, Clostridium difficile; C031815:toxB protein, Clostridium difficile