NOV 16, 2015 5:39 PM PST

Microbes, Beige Fat, and Obesity

WRITTEN BY: Kerry Evans
Researchers now have a better understanding of how gut microbes contribute to obesity.  

Mammals have white and brown fat cells.  Brown fat burns energy, while white fat stores it.  An excess of white fat leads to weight gain and can cause insulin resistance (¼ of a healthy adult’s body mass is white fat).  There is, however, a third type of fat cell - beige fat.  This type of fat develops within white fat tissue after exercise or exposure to the cold.  
 
Gut microbe diversity contributes to obesity.

What’s the connection between gut microbes and obesity?  It has been known for some time that gut microbe diversity differs between average and obese people, and researchers at the University of Geneva found that the absence of gut microbes causes white fat to morph into beige fat.  According to study author Mirko Trajkovski, “having observed that microbiota can affect the obesity onset, we suspected that microbiota depletion can change the insulin sensitivity by modifying the amount and balance of these various types of fat”.

The group tested the effects of a high-calorie diet on germ-free mice, mice pre-treated with antibiotics to deplete gut microbes, and control mice.  The control mice became obese and developed insulin resistance.  However, germ-free and antibiotic-treated mice maintained a healthy weight and did not develop insulin resistance.  White fat decreased and beige fat increased in the germ-free and antibiotic-treated mice, as they group predicted.

Trajkovski went on to investigate the mechanism by which beige fat develops.  When gut microbes are depleted, the number of eosinophils in white fat increases.  The eosinophils secrete cytokines that signal to macrophages.  These signals cause M1 macrophages to turn into M2 macrophages which then induce “browning” of white fat.

What’s next?  According to Trajkovski, "treating obesity with high doses of antibiotics is unrealistic -- mainly due to the risk of antibiotic resistance -- we want to explore alternative ways of suppressing or modifying the microbiota, and to identify the exact bacterial genes responsible for this phenomenon. We would then target only those, without having to deplete the entire microbiota”.
 
Sources: Science Daily, The Scientist, Nature, Wikipedia
About the Author
  • Kerry received a doctorate in microbiology from the University of Arkansas for Medical Sciences.
You May Also Like
FEB 17, 2021
Microbiology
A Microbial Cable That Uses Electricity to Live
FEB 17, 2021
A Microbial Cable That Uses Electricity to Live
There are species of bacteria that grow into centimeters-long colonies that have a cable shape and share a common coat. ...
MAR 23, 2021
Genetics & Genomics
Implementing Illumina NGS is a lot easier than you think.
MAR 23, 2021
Implementing Illumina NGS is a lot easier than you think.
Dr. John-Sebastian Eden is a Virologist at the Westmead Institute for Medical Research in Sydney, Australia. His group u ...
APR 18, 2021
Plants & Animals
Dogs Can Sniff Out COVID-19 Cases
APR 18, 2021
Dogs Can Sniff Out COVID-19 Cases
Dogs help us in a lot of ways. Now they may help us get back to normal after the pandemic by using their exceptional abi ...
APR 30, 2021
Coronavirus
J&J COVID-19 Vaccine Reaction Clusters Caused by Anxiety
APR 30, 2021
J&J COVID-19 Vaccine Reaction Clusters Caused by Anxiety
Vaccinating as many people as possible will be one of several efforts that will be needed to halt the progression of the ...
MAY 03, 2021
Microbiology
A New Bacterial Defense System is Discovered
MAY 03, 2021
A New Bacterial Defense System is Discovered
Most DNA that we're familiar with is found in cells in a double-stranded form. So, many years ago, scientists were intri ...
MAY 11, 2021
Clinical & Molecular DX
Every Minute Counts: Opportunities for Faster Blood Culture Results
MAY 11, 2021
Every Minute Counts: Opportunities for Faster Blood Culture Results
Sepsis is one of the most significant challenges in critical care, and early diagnosis is a decisive factor in determini ...
Loading Comments...