Vitamin A directs immune cells to intestines

Brett Smith for – @ParkstBrett

A new study conducted by researchers at Purdue University has found a metabolite resulting from the breakdown of vitamin A acts as a sort of GPS, directing certain disease- fighting cells to the body’s intestine.

“It is known that vitamin A deficiencies lead to increased susceptibility to disease and low concentrations of immune cells in the mucosal barrier that lines the intestines,” study author Chang Kim, a microbiologist and immunologist in Purdue’s College of Veterinary Medicine, said in a press release. “We wanted to find the specific role the vitamin plays in the immune system and how it influences the cells and biological processes.”

“The more we understand the details of how the immune system works, the better we will be able to design treatments for infection, and autoimmune and inflammatory diseases,” he added.

Published in the journal Immunology, the new study focused on immune system cells called innate immune cells that move quickly to eliminate an infection. These cells collect in lymph nodes before going their final destination.

In the lymph nodes, a vitamin A metabolite called retinoic acid acts upon two of three subsets of innate immune cells meant for the intestines. Kim and his team discovered that retinoic acid activates particular receptors in the cells that behave as tracking devices for the intestines. When the innate immune cells later traverse the circulatory system, the receptors seize and bind to molecules in the intestines whilst holding the cells in place.

The final location for these immune system cells is crucial because they both fight pathogens there and call for back up in the form of adaptive immune cells that are custom-made by the body to kill or neutralize the invaders.

“It is important that these cells be concentrated in mucosal barrier tissues (in the intestines), as opposed to scattered throughout the body, because these tissues are the point of entry for many infections from bacteria, viruses, and parasites,” Kim said. “Now that we have established the system of migration for these cells, we can play with it a little and see what changes the behavior and function of the cells.”

Kim added that vitamin D has also been found to guide immune cells, sending sets of them to the skin.

“We all know that what we eat significantly affects our overall health and immunity,” he said. “While there are other important regulators of immune system function, the role vitamins play is significant. How this works on a molecular level is a growing field of study.”


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