Skip Navigation
Archive

NIAID Archive

Important note: Information on this page was accurate at the time of publication. This page is no longer being updated.
​​
NIH HHS News Release Logo
National Institute of Allergy and
Infectious Diseases (NIAID)
http://www.niaid.nih.gov

FOR IMMEDIATE RELEASE
Monday, Feb. 2, 2004

Media Contact:
Anne A. Oplinger
(301) 402-1663
niaidnews@niaid.nih.gov
Skip Content Marketing
  • Share this:
  • submit to facebook
  • Tweet it
  • submit to reddit
  • submit to StumbleUpon
  • submit to Google +

Bacterial DNA Reduces Inflammation in Mice

DNA from inactivated "probiotic" bacteria triggers a specific anti-inflammation immune response in mice with experimental colitis, researchers supported by the NIH's National Institute of Allergy and Infectious Diseases (NIAID) have discovered. Led by Eyal Raz, M.D., of the University of California, San Diego (UCSD), the investigators provide a possible explanation for the observed benefits of consuming probiotics, supplements from bacteria and other microbes, regarded by some as helpful in maintaining or restoring intestinal health. Knowing how probiotics work could give scientists a way to identify and select which probiotic bacteria might be effective against such human ailments as inflammatory bowel disease (IBD).

Probiotics have shown promise for treating such IBDs as Crohn's disease and ulcerative colitis, both of which cause periodic intestinal inflammation. But scientists have had many theories of how these mixtures of "good" bacteria work, notes Marshall Plaut, M.D., of NIAID's Division of Allergy, Immunology and Transplantation. Plausible theories suggested that proliferation of the living bacteria either generated helpful metabolic products or crowded out "bad" intestinal bugs. Prior to this study, the general thinking about probiotics, which include bacteria like those found in yogurt, has been that they mediate their effects through some kind of non-specific action, adds Dr. Plaut.

Dr. Raz and his colleagues, whose work is published in the February 2004 issue of the journal Gastroenterology, irradiated a commercially available probiotic preparation, halting bacterial proliferation, but preserving its DNA. When given to mice, the irradiated probiotics performed as well as live bacteria in reducing inflammation. They also found that purified probiotic bacterial DNA alone similarly reduces inflammation in mice with experimentally induced colitis.

The researchers also showed that probiotic DNA acts in a specific way by activating a defined element within the innate immune system. In animals, including humans, components of the innate immune system play complementary roles in initiating, then halting, inflammation. Improperly regulated inflammation is one symptom of IBDs.

An innate immune system protein called TLR9 is a pivotal player in the chemical signaling chain that slows inflammation. In a series of experiments, the UCSD team showed that probiotic DNA exerts its effects through TLR9. Indeed, mice without the gene for TLR9 protein cannot benefit from probiotics, either living or irradiated, or from probiotic DNA.

Taken together, insights into mechanisms of probiotic activity open new possibilities for probiotic therapies. For example, say some researchers, purified probiotic DNA or irradiated probiotics may be safer than viable preparations, and could be used by people with compromised immune systems.

Dr. Raz also received support for this research from the National Institute of Diabetes and Digestive and Kidney Diseases, a part of the NIH.

###

For further information on current treatments or clinical trials of experimental treatments for inflammatory bowel disease (IBD), please visit the National Institute of Diabetes & Digestive & Kidney Diseases Web site - http://www.niddk.nih.gov.

To request information please contact:
National Digestive Diseases Information Clearinghouse
2 Information Way
Bethesda, MD 20892-3570
Phone: 1-800-891-5389
Web Contact Form: http://digestive.niddk.nih.gov/about/contact.htm


NIAID conducts and supports research—at NIH, throughout the United States, and worldwide—to study the causes of infectious and immune-mediated diseases, and to develop better means of preventing, diagnosing and treating these illnesses. News releases, fact sheets and other NIAID-related materials are available on the NIAID Web site at www.niaid.nih.gov.

About the National Institutes of Health (NIH): NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.

NIH...Turning Discovery Into Health ®

back to top


Archive

NIAID Archive

Important note: Information on this page was accurate at the time of publication. This page is no longer being updated.
​​​​

Last Updated February 03, 2004