title: Down-regulation of cytochrome P450 proteins and its activities by Shiga-like toxin II from Escherichia coli O157:H7.
abstract: Escherichia coli O157:H7 infection frequently induces clinical complications such as hemolytic uremic syndromes and intestinal dysfunctions. These changes could alter the disposition of drugs, consequently changing their efficacy. However, the possible changes of drug-metabolizing activities by E. coli O157:H7 infection have not been addressed. Thus, we have investigated the effect of Shiga-like toxin type II (SLT-II), derived from E. coli O157:H7, on the hepatic cytochrome P450 (CYP) content and its activity in rats. SLT-II (2microg per animal, i.v.) time-dependently decreased total CYP content and the contents of CYP2C11 and CYP3A2 in hepatic microsomal preparations up to 24hr following injection. Consistently, SLT-II time-dependently decreased CYP activity in vivo, as represented by systemic clearance of antipyrine. An inhibitor of inducible nitric oxide synthase, S-methylisothiourea, restored the decreased systemic clearance of antipyrine by SLT-II, suggesting the involvement of the overproduction of nitric oxide by SLT-II. Moreover, dexamethasone restored the decreased systemic clearance of antipyrine by SLT-II. In the hepatic microsomal preparation, dexamethasone restored the SLT-II-induced decrease of CYP3A2 whereas S-methylisothiourea did not affect both CYP subtypes. Taken together, these results suggest that SLT-II might alter hepatic drug-metabolizing function during E. coli O157 infection and that more than one cytokines induced by SLT-II, including nitric oxide, might make a critical contribution to the decrease of CYP content and its activity.
authors.affiliation: Department of Medical Technology, Nagoya University School of Health Sciences, 1-1-20, Daikominami, Higashi-ku, Nagoya 461-8673, Japan. hasegawa@met.nagoya-u.ac.jp
authors.forename: Kiyoyuki
authors.initials: K
authors.lastname: Kitaichi
authors.forename: Hironao
authors.initials: H
authors.lastname: Nakayama
authors.forename: Jun
authors.initials: J
authors.lastname: Ueyama
authors.forename: Masayuki
authors.initials: M
authors.lastname: Nadai
authors.forename: Kenji
authors.initials: K
authors.lastname: Baba
authors.forename: Kenji
authors.initials: K
authors.lastname: Takagi
authors.forename: Kenzo
authors.initials: K
authors.lastname: Takagi
authors.forename: Michio
authors.initials: M
authors.lastname: Ohta
authors.forename: Takaaki
authors.initials: T
authors.lastname: Hasegawa
mesh_terms: D000818:Animals; D000983:Antipyrine / Q000378:metabolism; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000187:drug effects / Q000378:metabolism*; D000072467:Cytochrome P450 Family 2; D003907:Dexamethasone / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects; D004347:Drug Interactions; D019453:Escherichia coli O157 / Q000737:chemistry*; D007550:Isothiuronium / Q000031:analogs & derivatives* / Q000494:pharmacology; D008099:Liver / Q000187:drug effects* / Q000201:enzymology; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D022641:Shiga Toxin 2 / Q000494:pharmacology*; D039181:Steroid 16-alpha-Hydroxylase / Q000378:metabolism; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; D022641:Shiga Toxin 2; D014409:Tumor Necrosis Factor-alpha; D007550:Isothiuronium; D009569:Nitric Oxide; D003907:Dexamethasone; D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases; C450279:CYP2C11 protein, rat; C465260:Cyp3a2 protein, rat; D051544:Cytochrome P-450 CYP3A; D000072467:Cytochrome P450 Family 2; D039181:Steroid 16-alpha-Hydroxylase; C027744:S-methylisothiopseudouronium; D000983:Antipyrine