Obesity May Be Affected by Defects in the Immune System as Seen in Mice

Researchers report in ScienceMag that mice have gained weight in addition to developing some health problems when they carried a genetic abnormality that affects the immune system.  Microbiome researcher at the University Of Utah School Of Medicine, June Round says that there is a chance that whatever is happening to the mice in the experiment is also happening to people.  In the experiment, they found that people found with obesity and type 2 diabetes have similar compositions of gut microbe and some immune system deficiencies as those in the mice.

In their research, the team looked at the mice having a defect in the Myd88 gene-the gene that is responsible for giving a protein stimulus to get involved with the immune system.  They observed that those with the defect in the said gene gained weight at five months old and those with a lack of the gene weighed twice as the regular weight at one year old.  The mice that have a defect in the Myd88 gene have also seemed to develop some problems with metabolism that are usually influenced by obesity, mainly insulin resistance, which is also the primary symptom of type 2 diabetes.  In comparison, the mice that lack the Myd88 gene were observed to have reduced activity in their T follicular helper cells-the cells that communicate with B cells in the immune system to facilitate the production of antibodies that fight or control certain microbes.

Similar to cases in humans, the mice with obesity were found to have fewer types and less Clostridia bacteria, but more Desulfovibrio bacteria found in their small intestines.  A similar pattern has also been observed in people with type 2 diabetes.  When the mice were given more Clostridia, they were observed to lose some weight.  However, the researchers were not able to give the mice more Desulfovibrio because their immune system quickly reacts to the bacteria.

It was then concluded after the research that altering the microbiomes in the small intestine affects how much fat is absorbed by the body.  The dose of extra Clostridia reduced the amount of fat absorbed, while an extra dose of Desulfovibrio did the opposite.  This may be interpreted as the Clostridia bacteria can protect the body against obesity, while the Desulfovibrio merely promotes obesity and is harmful to the body.  Of course, additional researches need to be done in order to fully prove this and determine the extent of help of the Clostridia genus in the intestines.