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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.

SUBMITTER: Lee JH

PROVIDER: S-EPMC3232668 | biostudies-literature | 2011 Dec

REPOSITORIES: biostudies-literature

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Apple flavonoid phloretin inhibits Escherichia coli O157:H7 biofilm formation and ameliorates colon inflammation in rats.

Lee Jin-Hyung JH Regmi Sushil Chandra SC Kim Jung-Ae JA Cho Moo Hwan MH Yun Hyungdon H Lee Chang-Soo CS Lee Jintae J

Infection and immunity 20110919 12

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 r ...[more]

PMID: 21930760

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Project description:Pathogenic biofilms have been associated with persistent infections due to high resistance to antimicrobial agents while commensal biofilms often fortify host immune system. Hence, controlling biofilm formation of both pathogenic bacteria and commensal bacteria is important in bacteria-related diseases. We investigated the effect of plant flavonoids on biofilm formation of both enterohemorrhagic Escherichia coli O157:H7 and three commensal E. coli K-12 strains. Phloretin 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 stx2), autoinducer-2 importer genes (lsrACDBF), a curli gene (csgA), and a dozens of prophage genes in E. coli O157:H7 cells. Electron microscopy confirmed that phroretin reduced the curli production in E. coli O157:H7. In addition, phloretin suppressed TNF-Î±-induced inflammatory response in vitro using human colonic epithelial cells. Moreover, in the trinitrobenzene sulfonic acid (TNBS)-induced rat colitis model, phloretin significantly ameliorated colon inflammation and body weight loss. Taken together, our results suggest that phloretin may act as an inhibitor of E. coli O157:H7 biofilm formation as well as anti-inflammatory agent on inflammatory bowel diseases while leaving beneficial commensal E. coli biofilm intact. For the microarray experiments, E. coli O157:H7 EDL933 was inoculated in 25 ml of LB in 250 ml flasks with overnight cultures that were diluted at 1:100. Cells were shaken at 100 rpm and 37Â°C for 7 hrs. Cells were immediately chilled with dry ice and 95% ethanol (to prevent RNA degradation) for 30 sec before centrifugation in 50 ml centrifuge tubes at 13,000 g for 2 min; cell pellets were frozen immediately with dry ice and stored -80Â°C. RNA was isolated using Qiagen RNeasy mini Kit (Valencia, CA, USA). To eliminate DNA contamination, Qiagen RNase-free DNase I was used to digest DNA. RNA quality was assessed by Agilent 2100 bioanalyser using the RNA 6000 Nano Chip (Agilent Technologies, Amstelveen, The Netherlands), and quantity was determined by ND-1000 Spectrophotometer (NanoDrop Technologies, Inc., DE, USA).

Project description:Two lineages of enterohemorrhagic (EHEC) Escherichia coli O157:H7 (EDL933, Stx1+ and Stx2+) and 86-24 (Stx2+) were investigated in regards to biofilm formation on an abiotic surface. Strikingly, EDL933 strain formed a robust biofilm while 86-24 strain formed no biofilm on either a polystyrene plate or a polyethylene tube. To identify the genetic mechanisms of different biofilm formation in two EHEC strains, DNA microarrays were first performed and phenotypic assays were followed. In the comparison of the EDL933 strain versus 86-24 strain, genes (csgBAC and csgDEFG) involved in curli biosynthesis were significantly induced while genes (trpLEDCB and mtr) involved in indole signaling were repressed. Additionally, a dozen of phage genes were differentially present between two strains. Curli assays using a Congo red plate and scanning electron microscopy corroborate the microarray data as the EDL 933 strain produces a large amount of curli, while 86-24 forms much less curli. Also, the indole production in the EDL933 was 2-times lower than that of 86-24. It was known that curli formation positively regulates and indole negatively regulates biofilm formation of EHEC. Hence, it appears that less curli formation and high indole production in the 86-24 strain are majorly responsible for no biofilm formation. For the microarray experiments, E. coli O157:H7 EDL933 and 86-24 were inoculated in 25 ml of LB in 250 ml shake flasks with overnight cultures that were diluted 1:100. Cells were shaken at 250 rpm and 37°C for an absorbance of 4.0 at 600 nm. Cells were immediately chilled with dry ice and 95% ethanol (to prevent RNA degradation) for 30 sec before centrifugation in 50 ml centrifuge tubes at 13,000 g for 2 min; cell pellets were frozen immediately with dry ice and stored -80°C. RNA was isolated using Qiagen RNeasy mini Kit (Valencia, CA, USA). RNA quality was assessed by Agilent 2100 bioanalyser using the RNA 6000 Nano Chip (Agilent Technologies, Amstelveen, The Netherlands), and quantity was determined by ND-1000 Spectrophotometer (NanoDrop Technologies, Inc., DE, USA).

Dataset Information

Apple flavonoid phloretin inhibits Escherichia coli O157:H7 biofilm formation and ameliorates colon inflammation in rats.

Publications

Apple flavonoid phloretin inhibits Escherichia coli O157:H7 biofilm formation and ameliorates colon inflammation in rats.

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