Immune Cells in Mesentery Limit Salmonella Spread, Study Finds

A recent study has illuminated a bodily mechanism that helps contain the spread of Salmonella infections, offering an explanation for the varying severity of symptoms among patients and paving the way for therapies aimed at boosting immunity.

Salmonella bacteria are among the most common causes of food poisoning, typically transmitted through consumption of raw or undercooked meat, poultry, unpasteurized dairy products, and occasionally from some pets. In most cases, the infection causes gastrointestinal symptoms such as vomiting and diarrhea, but it can sometimes escalate into severe systemic infections like typhoid fever.

This variability in infection severity motivated researcher Kyuuk Kim from the University of Illinois at Chicago (UIC) and his team to investigate why some infections remain confined to the intestines while others develop into life-threatening conditions.

The study, published in the Journal of Experimental Medicine, found that immune cells located in an organ called the mesentery play a crucial role in either limiting bacterial spread or, in some cases, permitting infection progression.

The mesentery is a spiral-shaped organ approximately 1.8 meters long, situated at the back of the abdominal cavity. It connects the intestines to other organs such as the liver, spleen, and pancreas, and contains a network of blood vessels, lymphatic vessels, and nerves.

Kim, a professor of pharmacology and regenerative medicine at the medical school, stated that the precise function of the mesentery remains not fully understood despite its anatomical connection to the small and large intestines. Researchers believe it provides structural support to internal organs and participates in regulating immune system activity.

The research concentrated on two types of immune cells within the mesentery: macrophages, which eliminate germs and damaged cells, and monocytes, which travel through the bloodstream to infection sites as needed.

Experiments conducted on mice demonstrated that cooperation between these two immune cell types helps prevent Salmonella from spreading beyond the intestines.

The findings also revealed that when macrophages were removed from the mesentery during infection, large numbers of monocytes flooded into the organ. This suggests that macrophages regulate monocyte entry to maintain immune response balance, since excessive immune cells can damage healthy tissue.

Kim believes that understanding the interaction between macrophages and monocytes in the mesentery could lead to new treatments aimed at modulating immune function, thereby aiding in the management of gastrointestinal infections and reducing complications from Salmonella.