A new study by researchers at Washington University School of Medicine in St. Louis finds that a certain type of tolerance-promoting immune cell has been found in mice that have a particular bacterium in their guts. According to reports, the authors of the new study found a particular kind of immune cell in mice who have a certain type of bacterium in their guts.
However, it is reported by Science Daily that the bacterium in question needs one of the building blocks of proteins – to be specific the tryptophan – to trigger the appearance of the cells. Tryptophan is mostly found in turkey and other protein-rich foods including eggs, nuts, seeds, poultry, beans, yogurt, cheese, chocolate, and much more. It is already clear that the presence of immune cells in the gut helps to strike a balance between harmful microbes in the food substances consumed and cells that promote tolerance.
It ensures that the harmful microbes do not get absorbed into the body and cause inflammation, this is achieved by ensuring its balance with cells that promote tolerance and protect the body without damaging any sensitive tissue. But when the balance between the two becomes too great, tilting towards inflammation, it could lead to inflammatory bowel disease.
“We established a link between one bacterial species – Lactobacillus reuteri – that is a normal part of the gut microbiome and the development of a population of cells that promote tolerance. The more tryptophan the mice had in their diet, the more of these immune cells they had,” Professor of Pathology at the Robert Rock Belliveau and senior author of the study, Marco Colonna said.
Meanwhile, it is reported that the findings of the new study suggest that the combination of a diet rich in tryptophan and L. reuteri could bring about a less inflammation and a more tolerant gut environment. If the findings of the study are to be considered, it could mean a new treatment solution for over a million Americans who are currently suffering from abdominal pain and diarrhea as a result of inflammatory bowel disease, according to a report by Eurekalert.
The report also states that the difference between mice living with the bacterium in their guts and those that were not was first discovered by Luisa Cervantes-Barragan Ph.D., a postdoctoral researcher. She was researching on a kind of immune cell that boost tolerance when she noticed that a group of mice had such cells, but another group of mice that were housed apart from the first group did not possess similar cells.
Although both groups of mice were genetically identical, they were born and raised separately. The researchers believe that this is indicative of the fact that environmental factor plays an important role on whether immune cells will develop or not. It is reported that Cervantes-Barragan, in collaboration with other researchers was able to sequence DNA from the intestines of the two groups of mice. The researchers found six bacterial species in the mice that had the immune cells but not in those without it.
They further investigated into the system of mice that have been living in sterile conditions to check which of the six species were associated with the immune cells. The researchers found that the mice lack a gut microbiome and do not have the immune cells but it became present when L. reuteri was added to the germ-free mice.
In addition, they grew L. reuteri in liquid, part of which was then transferred to immature immune cells that are isolated from mice in order to understand how the bacteria influenced the immune system. Interestingly, the immune cells grew into the tolerance-promoting cells but when the liquid was purified of the active component, it became a byproduct of tryptophan – a metabolism called indole-3-lactic acid.
However, the number of the immune cells increased significantly by about 50 percent when the amount of tryptophan was doubled in the mice’s feed and when the quantity of tryptophan was reduced by half, the number of immune cells reduced by half. The researchers published the findings of their study August 3 in the journal Science.