Gut bacteria is a hot topic in science today — and for good reason. Our intestines harbor more than 100 trillion bacteria and other gut microbial cells that influence our metabolism, nutrition, and general health and disease. Investigating a common bacterium in the intestine, Technion researchers have made a discovery that could lead to a better understanding and treatment of inflammatory bowel diseases (IBD) such as colitis and Crohn’s disease.

In a process of co-evolution with humans over millions of years, gut bacteria became essential to the proper functioning of our immune system and health, and acquired the ability to adapt to changes in their environment. “Understanding the role of bacteria in the development of intestinal disease and their severity is likely to advance innovative treatments directed at these bacteria,” said Professor Naama Geva-Zatorsky, who led the research at the Rappaport Faculty of Medicine.

Analyzing more than 2,000 healthy and sick individuals and conducting preclinical research in model mice, the Technion scientists found that Bacteroides fragilis, the most prevalent bacteria in the gut, can change its “software” in reaction to inflammation — activating or repressing the immune system.

These bacteria cover themselves with a molecule called Polysaccharide A (PSA) that induces a specialized subpopulation of regulatory T-cells (Tregs), which suppress immune responses and maintain homeostasis. The research demonstrated that when the gastrointestinal tract is inflamed, the bacteria undergo genomic inversions of DNA segments, causing them to “turn off” production of PSA. The “off” orientation gradually reversed as the inflammation in the model mice resolved. The researchers found a similar phenomenon in specific viruses in the gut, known as bacteriophages.

“This research unlocks the path for future researchers investigating the activity of bacteria as a condition for their living environment in the human body and their repercussions for our health,” said Prof. Geva-Zatorsky.

The research was supported by the European Research Council, the Technion President’s Fund, the Ruth and Bruce Rappaport Cancer Research Center, the Dan and Betty Kahn Foundation, and other noteworthy institutions.

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Naama Geva-Zatorsky
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Naama Geva-Zatorsky