Dietary Fat Impacts Autoimmune Flare-Ups In Mice

22 Oct 2015 --- Dietary fat may impact the severity and duration of autoimmune flare-ups, suggests a study published in the October journal Immunity. Adjusting the length of fatty acids consumed by mice altered the function of T helper cells in the gut--either intensifying or alleviating symptoms in an animal model of the autoimmune disease (i.e., multiple sclerosis).

A team led by Ralf Linker, of Friedrich-Alexander-University Erlangen-Nuremberg and his colleague Aiden Haghikia from the Ruhr-University Bochum in Germany compared in mice the effects of short-chain fatty acids, which are solely metabolized by gut bacteria and are typically found in fiber-rich diets, with the effects of long-chain fatty acids, the most abundant component of western diets.

They found that long-chain fatty acids, such as lauric acid and palmitic acid, promoted the development and release of proinflammatory T cells from the intestinal wall to other areas in the body, including the brain. This caused more severe disease in the mice. On the contrary, short-chain fatty acids, such as propionate, promoted the development and propagation of regulatory T cells that kept the immune response in check. This ameliorated the disease in the animals.

None of the effects of dietary fatty acids were seen in animals whose intestines were made germ-free, suggesting that gut bacteria are directly involved. Further experiments showed that the metabolic products of the bacteria, rather than certain bacterial strains, were important.

"Most approved immunotherapies weaken or block proinflammatory components of the immune system, but by strengthening regulatory pathways, for example by using propionate as a supplement to established drugs, therapies could be further optimized," Linker says.

"It is now our plan to employ our gained insights to develop innovative dietary add-on therapies to established immunotherapies in multiple sclerosis," Haghikia adds.

There is more and more research into the effects of the gut microbiota on autoimmune diseases such as MS and Parkinson’s and it is becoming more widely recognized that the products the bacteria themselves produce may be heavily implicated in the development and treatment of these types of diseases. This has led to the gut being described as the second brain because of the link via the gut-brain axis.