title: Apple flavonoid phloretin inhibits Escherichia coli O157:H7 biofilm formation and ameliorates colon inflammation in rats.
abstract: Pathogenic biofilms have been associated with persistent infections due to their high resistance to antimicrobial agents, while commensal biofilms often fortify the host's immune system. Hence, controlling biofilm formation of both pathogenic bacteria and commensal bacteria is important in bacterium-related diseases. We investigated the effect of plant flavonoids on biofilm formation of enterohemorrhagic Escherichia coli O157:H7. The antioxidant phloretin, which is abundant in apples, markedly reduced E. coli O157:H7 biofilm formation without affecting the growth of planktonic cells, while phloretin did not harm commensal E. coli K-12 biofilms. Also, phloretin reduced E. coli O157:H7 attachment to human colon epithelial cells. Global transcriptome analyses revealed that phloretin repressed toxin genes (hlyE and stx(2)), autoinducer-2 importer genes (lsrACDBF), curli genes (csgA and csgB), and dozens of prophage genes in E. coli O157:H7 biofilm cells. Electron microscopy confirmed that phloretin reduced fimbria production in E. coli O157:H7. Also, phloretin suppressed the tumor necrosis factor alpha-induced inflammatory response in vitro using human colonic epithelial cells. Moreover, in the rat model of colitis induced by trinitrobenzene sulfonic acid (TNBS), phloretin significantly ameliorated colon inflammation and body weight loss. Taken together, our results suggest that the antioxidant phloretin also acts as an inhibitor of E. coli O157:H7 biofilm formation as well as an anti-inflammatory agent in inflammatory bowel diseases without harming beneficial commensal E. coli biofilms.
authors.affiliation: School of Chemical Engineering, Yeungnam University, Gyeongsan 712-749, Republic of Korea.
authors.forename: Jin-Hyung
authors.initials: JH
authors.lastname: Lee
authors.forename: Sushil Chandra
authors.initials: SC
authors.lastname: Regmi
authors.forename: Jung-Ae
authors.initials: JA
authors.lastname: Kim
authors.forename: Moo Hwan
authors.initials: MH
authors.lastname: Cho
authors.forename: Hyungdon
authors.initials: H
authors.lastname: Yun
authors.forename: Chang-Soo
authors.initials: CS
authors.lastname: Lee
authors.forename: Jintae
authors.initials: J
authors.lastname: Lee
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D003092:Colitis / Q000139:chemically induced / Q000188:drug therapy / Q000382:microbiology; D004927:Escherichia coli Infections / Q000150:complications / Q000188:drug therapy*; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000502:physiology* / Q000648:ultrastructure; D019073:HT29 Cells; D006801:Humans; D027845:Malus / Q000737:chemistry*; D015394:Molecular Structure; D010693:Phloretin / Q000737:chemistry / Q000494:pharmacology*; D051381:Rats; D014302:Trinitrobenzenesulfonic Acid / Q000633:toxicity
chemical_list: D014302:Trinitrobenzenesulfonic Acid; D010693:Phloretin