Researchers have revealed how the Salmonella bacteria – one of the main causes of food poisoning – manages to multiply in the body and evade the immune system.
- Salmonella bacteria is one of the causes of food poisoning.
- Scientists have discovered how it works to trick immune defenses in the intestine.
- This could help treat certain illnesses like ulcerative colitis or Crohn’s disease.
Salmonellosis affects hundreds of thousands of people each year in France. According to Public Health France, cited byPasteur Institute198,000 cases of this bacterial infection are recorded every year, of which 183,000 are of food origin.
In the United States, researchers wanted to understand how the bacteria Salmonella managed to evade the immune system. They present their results in Proceedings of the National Academy of Sciences.
How does salmonella disrupt the nutritional balance in the intestine?
As scientists point out, the digestive system is home to billions of bacteria, many of which produce short-chain fatty acids (SCFAs) that help fight harmful pathogens. Logically, in the presence of these protective tools, the bacteria should not be able to reproduce. Andreas Bäumler, a professor at UC Davis in California and vice chair for research in the Department of Medical Microbiology and Immunology, and his team discovered that the pathogen alters the nutritional balance of the gut. “When salmonella enters the small intestine, it causes inflammation of the intestinal lining and disrupts the normal absorption of amino acids from food, they develop. This creates an imbalance of nutrients in the gut.” However, this allows the bacteria to obtain the resources necessary to survive and multiply in the large intestine, where the bacteria present generally slow down its growth.
The researchers obtained these results after a test on mice. They tracked the absorption of amino acids in the small and large intestines. This allowed them to discover that in mice infected with salmonella, the absorption of amino acids into the blood was reduced. “In fact, two amino acids, lysine and ornithine, became more abundant in the gut after infection, they observe. These amino acids helped salmonella survive by preventing the growth-inhibiting effects of SCFAs.”Scientific team shows that salmonella uses its own”virulence factors“, that is, disease-causing molecules, to activate enzymes that break down key amino acids like lysine.”This helps the pathogen avoid the protective effects of SCFAs and grow more easily in the gut.”they specify.
Digestive diseases: the importance of a healthy intestinal microbiota
These UC Davis researchers believe that this discovery could provide explanations for certain disorders characterized by imbalances in the intestinal environment, such as Crohn’s disease or ulcerative colitis. Ultimately, this could make it possible to develop new treatments to protect the intestinal microbiota.
“This research (…) not only allows us to better understand how the Salmonella bacteria works, but it also highlights the importance of maintaining a healthy intestinal microbiotaunderlines Lauren Radlinski, lead author of the study. Our findings could lead to new treatments that help support the microbiota during infection.”
