We all know that the microbes in our gut keep us healthy by keeping harmful bacteria out, maintaining our mood, and supplementing us with vitamins as well as many other functions. An imbalance or immune attack against these gut microbes is a reason why some diseases happen, such as Crohn’s Disease, and why people become sick from food poisoning (Salmonella). This is why the delicate balance between the type and population of bacteria in our guts is so important to our health.
Dirk Elewaut, one of the lead scientists, discovered that an increase in segmented filamentous bacteria (normal bacteria found in the gut of rodents) in young mice can lead to changes in immune-regulating lymphoid tissues of the gut. These changes ultimately compromise the tissue and cause the body to make antibodies against the mice’s own cells, giving rise to autoimmunity in older mice. Autoimmune diseases are caused when the immune system mistakenly attacks the body’s own healthy cells or contents with antibodies, possibly leading to diseases such as systemic (whole body) lupus erythematosus and systemic sclerosis.
Source Image: Science Photo Library – STEVE GSCHMEISSNER
For this study, the scientists manipulated mice by interfering mice development with lymphotoxin and Hox11, both important to the proper formation of secondary lymphoid organs (where immune cells become activated during infection, i.e. spleen, tonsils, lymph nodes, etc). The mice without secondary lymphoid organs were more susceptible to autoimmune diseases due to the lack of cellular responses that stopped immune cells from attacking tissues due to low levels of a specific type of immune class: T regulatory cells (they stopped self-reactive immune cells from growing). Approximately 1 in 4 mice in the study subsequently developed autoimmunity when there was an increase in the amount of segmented filamentous bacteria in the gut, revealing a correlation between the amount of bacteria and autoimmunity.
Although a correlation has been found, the team of scientists have not yet determined the mechanism by which an increase in a particular type of bacteria leads to an increase in autoimmunity; however, this may lead to a more comprehensive understanding of how lupus and sclerosis occurs in humans.
Feature Image Source: Beneficial Gut Bacteria by NIH Image Gallery
