DNA from probiotic bacteria modulates murine and human epithelial and immune function.
OBJECTIVE
The intestinal epithelium must discriminate between pathogenic and nonpathogenic bacteria and respond accordingly. The aim of this study was to examine whether bacterial DNA can serve as the molecular basis for bacterial recognition.


METHODS
HT-29 monolayers were treated with various bacterial DNA and interleukin (IL)-8 secretion measured by enzyme-linked immunosorbent assay, nuclear factor kappaB activation by electrophoretic mobility shift assay and reporter assays, and IkappaB levels by Western blotting. Cytokine secretion in response to bacterial DNA was measured in murine colonic segments and splenocytes. IL-10-deficient mice were fed DNA from VSL probiotic compound daily for 2 weeks. Colons were removed and analyzed for cytokine production and inflammation.


RESULTS
HT-29 cells responded with IL-8 secretion to bacterial DNA in a differential manner. In the presence of proinflammatory stimuli, VSL3 DNA inhibited IL-8 secretion, reduced p38 mitogen-activated protein kinase activation, delayed nuclear factor kappaB activation, stabilized levels of IkappaB, and inhibited proteasome function. VSL3 DNA inhibited colonic interferon (IFN)-gamma secretion in mouse colons and also attenuated a Bacteroides vulgatus-induced IFN-gamma release from murine splenocytes. In mice, VSL3 DNA attenuated a systemic release of tumor necrosis factor alpha in response to Escherichia coli DNA injection. Treatment of IL-10-deficient mice with oral VSL3 DNA resulted in a reduction in mucosal secretion of tumor necrosis factor alpha and IFN-gamma and an improvement in histologic disease.


CONCLUSIONS
DNA from probiotic bacteria can limit epithelial proinflammatory responses in vivo and in vitro. Systemic and oral administration of VSL3 DNA ameliorates inflammatory responses.
Jijon
Humberto
H
Division of Gastroenterology, University of Alberta, Edmonton, Alberta, Canada T6G 2N8.
Backer
Jody
J
Diaz
Hugo
H
Yeung
Helen
H
Thiel
David
D
McKaigney
Conor
C
De Simone
Claudio
C
Madsen
Karen
K
D000818:Animals; D018407:Bacterial Physiological Phenomena; D004269:DNA, Bacterial / Q000008:administration & dosage / Q000494:pharmacology*; D004751:Enteritis / Q000517:prevention & control*; D004789:Enzyme Activation / Q000187:drug effects; D004926:Escherichia coli / Q000235:genetics; D019073:HT29 Cells; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D007267:Injections; D007371:Interferon-gamma / Q000037:antagonists & inhibitors; D016753:Interleukin-10 / Q000172:deficiency; D016209:Interleukin-8 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000187:drug effects / Q000502:physiology; D019936:Probiotics / Q000737:chemistry*; D012475:Salmonella / Q000235:genetics; D013154:Spleen / Q000166:cytology / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases
D004269:DNA, Bacterial; D020672:I-kappa B Proteins; D016209:Interleukin-8; D008070:Lipopolysaccharides; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D007371:Interferon-gamma; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases