title: Disruption of the epithelial barrier by botulinum haemagglutinin (HA) proteins - differences in cell tropism and the mechanism of action between HA proteins of types A or B, and HA proteins of type C.
abstract: Orally ingested botulinum neurotoxin (BoNT) causes food-borne botulism, but BoNT must pass through the gut lining and enter the bloodstream. We have previously found that type B haemagglutinin (HA) proteins in the toxin complex play an important role in the intestinal absorption of BoNT by disrupting the paracellular barrier of the intestinal epithelium, and therefore facilitating the transepithelial delivery of BoNT. Here, we show that type A HA proteins in the toxin complex have a similar disruptive activity and a greater potency than type B HA proteins in the human intestinal epithelial cell lines Caco-2 and T84 and in the canine kidney epithelial cell line MDCK I. In contrast, type C HA proteins in the toxin complex (up to 300 nM) have no detectable effect on the paracellular barrier in these human cell lines, but do show a barrier-disrupting activity and potent cytotoxicity in MDCK I. These findings may indicate that type A and B HA proteins contribute to the development of food-borne botulism, at least in humans, by facilitating the intestinal transepithelial delivery of BoNTs, and that the relative inability of type C HA proteins to disrupt the paracellular barrier of the human intestinal epithelium is one of the reasons for the relative absence of food-borne human botulism caused by type C BoNT.
authors.affiliation: Laboratory for Infection Cell Biology, International Research Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
authors.forename: Yingji
authors.initials: Y
authors.lastname: Jin
authors.affiliation: Laboratory for Infection Cell Biology, International Research Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Takegahara
authors.affiliation: Laboratory for Infection Cell Biology, International Research Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
authors.forename: Yo
authors.initials: Y
authors.lastname: Sugawara
authors.affiliation: Laboratory for Infection Cell Biology, International Research Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
authors.forename: Takuhiro
authors.initials: T
authors.lastname: Matsumura
authors.affiliation: Laboratory for Infection Cell Biology, International Research Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
authors.forename: Yukako
authors.initials: Y
authors.lastname: Fujinaga
mesh_terms: D000818:Animals; D001692:Biological Transport; D001905:Botulinum Toxins / Q000737:chemistry* / Q000145:classification / Q000378:metabolism; D019274:Botulinum Toxins, Type A / Q000737:chemistry / Q000378:metabolism; D018938:Caco-2 Cells; D045744:Cell Line, Tumor; D004285:Dogs; D017097:Electric Impedance; D004847:Epithelial Cells / Q000187:drug effects*; D006388:Hemagglutinins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D007422:Intestines / Q000166:cytology*; D007668:Kidney / Q000166:cytology*
chemical_list: D006388:Hemagglutinins; C096323:rimabotulinumtoxinB; D001905:Botulinum Toxins; D019274:Botulinum Toxins, Type A; C096324:botulinum toxin type C