Diet may affect inflammatory bone disease

Posted Oct 7, 2014 by Tim Sandle
Changes to the bacterial ecosystem of the human gut, induced by certain diets, can alter the chances of inflammatory bone diseases developing. This is because the bacteria are able to modify the immune response.
For the research, scientists used mice. The mice used were designed to replicate an inflammatory childhood bone disorder called chronic recurrent multifocal osteomyelitis (CRMO). Here the bones have lesions and inflammation, which leads to considerable pain.
To create the disorder, the mice were genetically modified to be born with a gene mutation in the Pstpip2 gene. This gene is seen as being responsible for osteomyelitis. Through a series of studies, the scientists were able to demonstrate that changing the diet fed to the mice led to significant increases and decreases of certain intestinal bacteria. In the worst case conditions, a change to nutrients led to an increase of a bacterium called Prevotella. These bacteria have been linked to conditions like osteomyelitis, arthritis and periodontal disease. Each of these is an inflammatory condition.
In contrast, another type of diet reduced the population of Prevotella bacteria. This reduction prevented the mice from developing osteomyelitis. The reason for this appears to be a reduced production of an immune system molecule called interleukin-1 beta (IL-1 beta). This molecule is associated with inflammation.
To confirm the link between gut bacteria and osteomyelitis, the biologists administered a new group of transgenic mice with several broad-spectrum antibiotics (designed to kill bacteria). This led to a reduction in the Prevotella population (as well as other bacteria) and it led to a fall in levels of Il-1 beta. These mice did not develop osteomyelitis.
The new finding shows how the bacteria that live in the intestines affect health and also how diet affects the types of bacteria that predominate. With the diets it would seem that those who eat plenty of protein and animal fats have fewer Prevotell bacteria, while for those who consume more carbohydrates, especially fiber, the Prevotella species dominate.
The study was led by Thirumala-Devi Kanneganti and it was carried out at the St. Jude Children’s Research Hospital. The findings have been published in the journal Nature, in a paper headed “Dietary modulation of the microbiome affects autoinflammatory disease”.