New Study Reveals How Immune Cells in the Gut Help Prevent Salmonella from Spreading

CHICAGO, IL — Widely recognised as a leading cause of severe food poisoning, Salmonella bacteria can lurk in raw meat, poultry, pets, and unpasteurized dairy. If left untreated, extreme cases can escalate from typical digestive discomfort into dangerous, full-body infections like Typhoid fever. However, a groundbreaking new study from the University of Illinois Chicago (UIC) has revealed exactly how the body blocks this deadly progression, pointing to a critical yet historically mysterious organ: the gut mesentery.

The study, published in the Journal of Experimental Medicine, has revealed how immune cells in the gut mesentery help prevent Salmonella bacteria from spreading throughout the body. The findings could help researchers develop new treatments for gastrointestinal infections by better understanding how the immune system responds to harmful bacteria.

The gut mesentery is a long, folded organ inside the abdomen that connects the intestines to other organs, including the liver, pancreas, and spleen. Besides supporting these organs, it contains blood vessels, lymph nodes, nerves, and many immune cells.

Although scientists have known about the mesentery for years, its role in fighting infections has remained unclear.

Using mouse models, the UIC research team—led by Kiwook Kim, a professor of pharmacology and regenerative medicine—tracked the behavior of two vital types of immune cells residing within the mesentery:

• Macrophages: Immune cells that live in tissues and remove harmful bacteria and damaged cells.

• Monocytes: Travel through the bloodstream and migrate to sites of infection when needed.

The study showed that macrophages help control the number of monocytes entering the mesentery. When macrophages were removed, too many monocytes entered the tissue, which could lead to excessive inflammation and tissue damage.

The study's big discovery is that immune cells called macrophages act like biological "bouncers" in the gut. During a Salmonella infection, they strictly control how many other immune cells (monocytes) are allowed to enter from the blood.

When researchers experimentally removed the macrophages, monocytes flooded the mesentery in an uncontrolled surge. This indicated that without the regulatory "bouncers" present, an overabundance of immune cells can cause severe inflammation and tissue damage.

"Understanding the relationship between macrophages and monocytes in this portion of the gut can help us manipulate immune cells and develop therapies to treat gastrointestinal infections," stated Professor Kim.

Demonstrating that the gut mesentery acts as a protective shield, this research opens a new avenue for treating stomach illnesses. Instead of just using standard antibiotics, future medical treatments could boost the body's natural defences. This could help patients fight off severe food poisoning and extreme infections naturally.

The study, "How immune cells in our gut mesentery fight Salmonella," was authored by first-author Jiseon Kim, a postdoctoral research associate, and senior author Kiwook Kim of the University of Illinois Chicago College of Medicine and the UIC Cancer Center.

(SP/NW)