This news release is available in German.
Trillions of microorganisms colonize our gut and together form the intestinal flora that coats the inside of the intestine. The duties of these gut microorganisms are manifold: they digest food, produce nutrients, eliminate pollutants and interact with the human immune system. An imbalance in these microorganisms can cause abdominal pain, constipation or diarrhea. In the Western world an unhealthy diet, lack of exercise, stress and excessive use of antibiotics also lead to ever-increasing numbers of patients with chronic inflammatory bowel diseases such as colitis but also bowel cancer.
Chronic inflammatory bowel diseases and the role of interferons
Colitis - a chronic inflammation of the intestine - is treated with anti-inflammatory drugs. However, the signaling pathways involved in this inflammation are still not fully understood. New findings could therefore provide important cues for better or completely new treatment options. The team of Thomas Decker from the Max F. Perutz Laboratories (MFPL) of the University of Vienna has now studied the role of interferons, a group of tissue hormones, in the development of colitis. "There are three types of interferons - our tests have shown that each type affects colitis differently. Type I interferons play a minor role, while type II interferons reinforce and type III interferons protect from the inflammation," explains Decker.
Surprising role of type II interferons
These first results triggered the interest of the scientists to find out exactly how the three interferon types mediate their different functions in colitis. Isabella Rauch, Postdoc and co- first author of the study, explains: "Our guess was that IRF9 would play a central role. This molecule transduces the signals of type I and III interferons, and therefore mediate the protective function of these interferons during the inflammatory response in colitis." Colleague and co-first author Felix Rosebrock adds: "However, what we found was that IRF9's main impact was not to transduce type I and III signals in colitis, but those of the type II interferons and thus to aggravate the inflammation." The researchers showed that the type II interferon signals cause the release of CXCL10, an attractant for cells that promote the inflammation.
New approaches for the treatment of colitis
The results of the study provide a new impetus for the treatment of colitis. They not only underpin the chances of success for a clinical trial of antibodies that inhibit the function of the attractant CXCL10, but also suggest that direct administration of type III interferons could protect patients from the inflammatory responses that trigger colitis.
The project was supported by the Austrian Science Fund FWF and the Austrian Federal Ministry of Science, Research and Economics.
Publication in "Molecular and Cellular Biology"
Noncanonical effects of IRF9 in intestinal inflammation: more than type I and type III interferons. Isabella Rauch, Felix Rosebrock, Eva Hainzl, Susanne Heider, Andrea Majoros, Sebastian Wienerroither, Birgit Strobl, Silvia Stockinger, Lukas Kenner, Mathias Mueller and Thomas Decker, in Molecular and Cellular Biology, 2015.