Colorized SEM (scanning electron micrograph) of the foodborne pathogen Salmonella enteritidis. Blue is development medium. Image is coloured in false colours for instance distinction. Picture by Jean Guard, ARS. Credit score: U.S. Division of Agriculture/public area
A brand new UC Davis Well being examine has uncovered how Salmonella micro organism, a significant reason for meals poisoning, can invade the intestine even when protecting micro organism are current. The analysis, printed within the Proceedings of the Nationwide Academy of Sciences, explains how the pathogen methods the intestine setting to flee the physique’s pure defenses.
The digestive system is dwelling to trillions of micro organism, lots of which produce short-chain fatty acids (SCFAs) that assist battle dangerous pathogens. However Salmonella manages to develop and unfold within the intestine, though these protecting compounds are current. The examine asks: How does Salmonella get round this protection?
“We knew that Salmonella invades the small intestine, although it is not its primary site of replication. The colon is,” mentioned the lead creator of the examine Andreas Bäumler. Bäumler is a UC Davis distinguished professor and vice chair of analysis within the Division of Medical Microbiology and Immunology.
Bäumler and his workforce found that the reply lies in how the pathogen modifications the intestine’s nutrient steadiness. When Salmonella enters the small gut, it causes irritation within the intestine lining and disrupts the conventional absorption of amino acids from meals. This creates an imbalance in vitamins within the intestine.
The imbalance provides Salmonella the sources it must survive and multiply within the giant gut (colon), the place helpful micro organism normally curb its development. The examine confirmed that salmonella causes irritation within the small gut as a way to derive vitamins that gas its replication within the colon.
Salmonella alters intestine nutrient setting to outlive
Utilizing a mouse mannequin, the workforce regarded carefully at how Salmonella modified the chemical make-up of the intestine. They traced amino acid absorption within the small and huge intestines.
They discovered that in mice that had been contaminated with Salmonella, there was much less absorption of amino acids into the blood. In reality, two amino acids, lysine and ornithine, turned extra ample within the intestine after an infection. These amino acids helped Salmonella survive by stopping the growth-inhibiting results of SCFAs. They did this by restoring Salmonella’s acidity (pH) steadiness, permitting the pathogen to bypass the microbiota’s defenses.
“Our findings show that Salmonella has a clever way of changing the gut’s nutrient environment to its advantage. By making it harder for the body to absorb amino acids in the ileum, Salmonella creates a more favorable environment for itself in the large intestine,” Bäumler mentioned.
Within the examine, the workforce confirmed that Salmonella makes use of its personal virulence elements (illness inflicting molecules) to activate enzymes that break down key amino acids like lysine. This helps the pathogen keep away from the SCFAs’ protecting results and develop extra simply within the intestine.
New insights might result in higher intestine an infection therapies
The brand new insights doubtlessly clarify how the intestine setting modifications throughout inflammatory bowel problems , resembling Crohn’s illness and ulcerative colitis, and will result in higher therapies for intestine infections. By understanding how Salmonella modifications the intestine setting, researchers hope to develop new methods to guard the intestine microbiota and forestall these infections.
“This research uses a more holistic approach to studying gut health. It not only gives us a better understanding of how Salmonella works, but also highlights the importance of maintaining a healthy gut microbiota,” mentioned Lauren Radlinski, the examine’s first creator and postdoctoral fellow within the Bäumler Lab. “Our findings could lead to new treatments that help support the microbiota during infection.”
The examine’s outcomes might encourage future therapies, together with probiotics or dietary plans designed to strengthen the physique’s pure defenses towards dangerous pathogens.
“By learning how a pathogen manipulates the host’s system, we can uncover ways to boost the host’s natural defenses,” Radlinski mentioned.
Co-authors of the examine are Andrew Rogers, Lalita Bechtold, Hugo Masson, Henry Nguyen, Anaïs B. Larabi, Connor Tiffany, Thaynara Parente de Carvalho and Renée Tsolis of UC Davis.
Extra data:
Lauren C. Radlinski et al, Salmonella virulence elements induce amino acid malabsorption within the ileum to advertise ecosystem invasion of the big gut, Proceedings of the Nationwide Academy of Sciences (2024). DOI: 10.1073/pnas.2417232121
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