As food enters the intestine, it embarks on a lengthy journey. For most of the route, its surroundings don't appear to change much. But new research conducted by researchers at the Rockefeller University shows that the food-processing canal consists of compartments with less aggressive defenses in the first segments where nutrients are absorbed and more forceful responses at the end, where pathogens are eliminated.
In their research published in the journal Nature, the researchers added pathogens such as Salmonella to the food provided to the studied mice. They found that the lymph nodes, which orchestrate immune responses, vary from one location to another, and they are more powerful in the deep parts of the intestine.
“The findings show that responses are separated by location. The first parts are responsible for the absorption of nutrients, therefore, a mild response is seen, and then, the system focuses more aggressively on eliminating pathogens without interfering with food uptake,” Daniel Mucida, from the Laboratory of Immunology at the Rockefeller University, and head of the research team, said in report published on the university's website on May 23.
According to Mucida, the immunological differences between the gut segments could be exploited for a number of therapeutic purposes, including for treating gastrointestinal disorders.
"For example, by targeting immune-suppressing drugs to the segment where they'll have the most effect, it might be possible to dampen their side-effects. Additionally, outcomes of surgeries that remove part of the intestine could improve if variations between segments were taken into account," he added. The spectrum of immune responses along the intestine could also be used to make new and better oral vaccines instead of injections.
According to Mucida, scientists' efforts to design oral vaccines have been stymied by the difficulty of generating a robust immune response that leads to a strong immune memory of the pathogen needed to prepare the body against recurring attack. The immune response at the beginning of the intestine might be part of the reason why oral vaccines tend to be less effective than injections, he noted.
"Targeting the right area of the gut may help produce oral vaccines," Mucida said.
