Bowel bacteria can cause brain damage, stroke

Recently, scientists have found a link between abnormalities of cerebral vessels and bacteria in the stomach.

This is the result of the study to find the connection between the intestine and the brain-related diseases.

Malformations that can lead to stroke are called cerebral birth defects (CCMs). When suffering from this disease, patients do not have many options. If surgery is not possible, there is only one way to take care to temporarily ease the pain.

But if scientists can find out the cause of these abnormalities, there will be treatments to prevent the disease even before it happens.

An international research group led by the University of Pennsylvania (USA), studied mice injected with genes that developed vascular lesions in the brain.

Previous research has shown that genetic patterns of this condition can be caused by mutations of certain genes. These genes often inhibit important signals, which affect the development of brain cells that form blood vessel walls.

Gut bacteria are related to brain diseases.(Photo: Shutterstock).

Although new research can help identify people at risk of developing CCM, there are currently no drugs that replace the role of lost genes. So we still can't do much for patients.

Genetic mutations are not the same for every person, so CCM changes significantly in each patient. So there is much more to learn than the destroyed genes.

By studying two genetically engineered mouse populations over generations, researchers have discovered new things. Accordingly, there are individuals who may be resistant to the development of lesions, although they still carry one of the CCM mutations.

Among these mice with resistance, there are a few that continue to develop malformations. However, these small mice may help explain the underlying causes of the disease.

Scientists have examined the role of infection in the development of CCM. 16 "drug-resistant" mice were injected with a live Gram-negative bacterium called Bacteroides fragilis, often found in the intestine.

Among them, 9 mice developed vascular lesions and pneumonia. This suggests that bacteria have spread from an infected place and affect the growth of lining cells of cerebral vessels.

Typically, gram-negative bacteria such as B. fragilis affect cell responses in mammals such as humans and mice. Influence through a molecule on the outer membrane is called lipopolysaccharide (LPS), or endotoxin.

To see if these molecules are capable of causing deformities, the group injected endotoxin from bacteria into mice created with mutant genes, as well as normal, non-genetic mice.

As a result, mice with broken genes are more likely to develop CCM, leading to vascular lesions in the brain. Meanwhile, mice without genetic mutations are not infected.

The lining cells of brain blood vessels are called the 'brain's blood barrier'. They often prevent toxic materials like endotoxin and bacterial cells from entering our central nervous system. But how endotoxin can affect these cells is still a mystery.

Jaesung Peter Choi - one of the researchers at the University of Sydney, Australia, told ScienceAlert: ' The mystery still needs to be investigated. However, we think that CCM formation is triggered by activation of immune receptors on the blood surface of the blood barrier of the brain. "

When these immune receptors, called TLR4, are activated by an endotoxin, the cells of the brain blood barrier are stimulated to develop abnormally. Related genes will often prevent deformities, but in mutated mice, there is nothing to prevent this process.

It is important that differences in TLR4 immune receptors in humans can also explain some variants in people with CCM mutations.

The scientists compared CCM-sensitive mice with free bacteria and those in sterile conditions. The results showed that bacteria in the environment play an important role in turning mutations into a deadly disease.

Although it may be possible to develop therapies targeted at TLR4 immune receptors, the researchers suggest focusing on intestinal bacteria.

" Understanding the interactions of intestinal microorganisms is a potential way to treat a long-term illness like CCM," the team said .