Gut Bacteria vs. Immune System

Have you ever thought about what is in your intestines? Im not just talking about the garbage called poop. There is also lots of good and bad bacteria in the long halls going toward the porcelain throne.

They now have new information about the role of vitamin A in the relationship between gut bacteria and the immune system, and that it may prove critical for devising new therapies for autoimmune conditions.  These would include Crohn’s disease, ulcerative colitis and other inflammatory diseases that affect the intestine.  Ana Sandoiu highlighted this information in her article which was fact checked by Paula Field.

A crucial role for gut bacteria is in keeping us healthy.  It has been shown by research that trillions of friendly microorganisms hosted by the gut can keep us lean, young and healthy in mind and body.

How does this happen?  One of the ways involves the immune system. Other studies have slowly unraveled the complex relationship between the gut bacteria and immunity and suggests the interactions between the host’s gut and the bacteria that colonize the intestines helps to control how the body responds to illness.

It has been known for some time by the scientists that the microbiome helps to regulate immune responses, but many of the detailed mechanisms behind this interaction are still unknown.  Some are how the body’s immune system exactly reacts, which is designed to protect us against pathogens, and allows for these friendly bacteria  to live happily in our gut.

Vitamin A in moderate levels may be an answer, as found by a team of scientists that were led by Shipra Vaishnava, an assistant professor of molecular microbiology and immunology at Brown University in Providence, RI.  The findings have been published in the journal Immunity and could have important implications for autoimmune disorders, such as Crohn’s disease.

There are over 100 trillion bacteria in the gut that are mainly divided into the phyla Firmicutes and Bacteroidetes.  The team used a mouse model of the microbiome and found these gut bacteria regulate their hosts’ immune responses by adjusting a protein that activates vitamin A in the gastrointestinal tract, called retinol dehydrogenase 7 (Rdh7) as it transforms vitamin A to retinoid acid.

They also found that Firmicutes bacteria lower the expression of Rdh7, which is part of the Clostridia family that causes the liver to store an increased amount of vitamin A.  The team genetically designed mice lacking Rdh7 in the cells lining their intestines.  The rodents had deficient levels of retinoid acid in their intestinal tissue, and fewer immune cells that make IL-22 molecules, which is a signaling molecule directing the immune system’s antimicrobial response.

They believe that understanding the interactions between the gut bacteria and immune response can be critical in determining therapies for autoimmune diseases, such as Crohn’s disease or other inflammatory bowel diseases, as well as vitamin A deficiency.  Researchers also highlight the role of diet and gut bacteria for keeping the immune system healthy, as both are critically linked in regulating how our immune cells behave.

Dr Fredda Branyon