title: The Shiga toxin 2 B subunit inhibits net fluid absorption in human colon and elicits fluid accumulation in rat colon loops.
abstract: Shiga toxin (Stx)-producing Escherichia coli (STEC) colonizes the large intestine causing a spectrum of disorders, including watery diarrhea, bloody diarrhea (hemorrhagic colitis), and hemolytic-uremic syndrome. It is estimated that hemolytic-uremic syndrome is the most common cause of acute renal failure in infants in Argentina. Stx is a multimeric toxin composed of one A subunit and five B subunits. In this study we demonstrate that the Stx2 B subunit inhibits the water absorption (Jw) across the human and rat colonic mucosa without altering the electrical parameters measured as transepithelial potential difference and short circuit current. The time-course Jw inhibition by 400 ng/ml purified Stx2 B subunit was similar to that obtained using 12 ng/ml Stx2 holotoxin suggesting that both, A and B subunits of Stx2 contributed to inhibit the Jw. Moreover, non-hemorrhagic fluid accumulation was observed in rat colon loops after 16 h of treatment with 3 and 30 ng/ml Stx2 B subunit. These changes indicate that Stx2 B subunit induces fluid accumulation independently of A subunit activity by altering the usual balance of intestinal absorption and secretion toward net secretion. In conclusion, our results suggest that the Stx2 B subunit, which is non-toxic for Vero cells, may contribute to the watery diarrhea observed in STEC infection. Further studies will be necessary to determine whether the toxicity of Stx2 B subunit may have pathogenic consequences when it is used as a component in an acellular STEC vaccine or as a vector in cancer vaccines.
authors.affiliation: Laboratorio de Fisiopatogenia, Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: V Pistone
authors.initials: VP
authors.lastname: Creydt
authors.forename: M Fernandez
authors.initials: MF
authors.lastname: Miyakawa
authors.forename: F
authors.initials: F
authors.lastname: Martín
authors.forename: E
authors.initials: E
authors.lastname: Zotta
authors.forename: C
authors.initials: C
authors.lastname: Silberstein
authors.forename: C
authors.initials: C
authors.lastname: Ibarra
mesh_terms: D000328:Adult; D000818:Animals; D002522:Chlorocebus aethiops; D003106:Colon / Q000187:drug effects* / Q000378:metabolism; D003967:Diarrhea / Q000382:microbiology; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli; D006801:Humans; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000378:metabolism; D017136:Ion Transport / Q000187:drug effects; D008297:Male; D021122:Protein Subunits / Q000633:toxicity*; D051381:Rats; D017207:Rats, Sprague-Dawley; D022641:Shiga Toxin 2 / Q000633:toxicity*; D014709:Vero Cells; D014867:Water / Q000378:metabolism*
chemical_list: D021122:Protein Subunits; D022641:Shiga Toxin 2; C450841:shiga toxin 2 B subunit; D014867:Water