The microbiome: how gut bacteria make the brain sick

But not every woman who goes through an infection during pregnancy ends up having a baby with a neurodevelopmental disorder, Huh says. There must be something causing the mother’s immune system to overreact in some cases. In their search for a cause, both Choi and Huh focused on a specific type of gut microbiome that has previously been shown to enhance the formation of helper type 17 T cells. When they treated the pregnant mice with an antibiotic to kill these bacteria and then stimulated the immune response, the offspring showed no behavioral problems..

Mauro Costa Mattioli, a neuroscientist at Baylor College of Medicine in Texas, is also studying the relationship between bacteria and ASA. Instead of looking for the microbes that promote the development of symptoms, he found one that could reduce their severity. Costa Mattioli discovered it by accident about five years ago. At the time, he was working on mice with offspring who had symptoms similar to autism. When these mice were housed with the neurotypic mice (and ate their droppings, as all mice do), their ASD-like behaviors disappeared. Costa Mattioli and colleagues found that the infected mice were missing a specific type of bacteria: Lactobacillus rotary.

Block the pathway for bacteria to reach the brain

Like auditions with L. reuteri It showed in several other mouse models that the bacteria were actually able to ameliorate some of the ASA-like behaviors. And just as with Parkinson’s disease, researchers were able to block the effect in mice if they severed the vagus nerve..

What kind of signal L. reuteri Exactly sends not yet known. Some strains of bacteria are beneficial to ASA mice, others are not. Researchers are currently trying to find out which genes are present in bacteria. If a gene is found that produces a major metabolite, “we can simply insert it into any bacteria and have a potential treatment,” says Costa Mattioli. However, many tests are needed for this.

A group in Italy is already testing the bacteria as a treatment in 80 children with ASA. Participants take six months L. reuteri Or a placebo pill and monitor for symptoms. Costa Mattioli hopes to start his own studies soon. It remains to be seen whether this approach will work. However, some colleagues have already expressed their doubts. Kevin Mitchell, a neurogenetics specialist at Trinity College Dublin, didn’t find the mouse studies convincing enough. He believes that discussion of the therapeutic potential is premature and “somewhat irresponsible” given the complexity of autism spectrum disorders.

Transferring results from animal studies to humans is difficult

Parkinson’s disease, Alzheimer’s disease, ALS, or ASS: There are still many unanswered questions. Despite much evidence, it remains unclear how exactly intestinal bacteria transmit their signals to the brain. Transferring the results of animal studies to humans is also difficult.

John Crean saw the data pile up after his talk on the topic was met with disinterest and silence. He found the evidence so far compelling and still believes in the potential of microbiome-focused therapies. “Unlike our own genome, which we cannot change much, our microbiome can be modified. This gives the patient a lot of room to operate,” he says. “This is really exciting.”