Can this bacteria cause Parkinson’s disease?

Researchers note that patients with Parkinson’s disease often have a slow stomach for many years before diagnosis.

Studies have also been done showing that Parkinson’s patients have a different composition of intestinal bacteria than others.

Clumps of alpha-synuclein, which builds up in neurons in Parkinson’s disease, are found in the nervous system in the stomach as well as in the brain. According to an article in Scientific American.

Therefore it is suggested that Parkinson’s disease It can start in the gut. But this was not decided.

Researchers are working to discover mechanisms in the gut that might play a role.

In a new study, Finnish researchers take a closer look at a bacterium they believe may be contributing to the disease.

Is there a relationship with Parkinson’s disease?

The bacteria are called Desulfovibrio. They are commonly found in environments with water. According to Wikipedia.

Per-Erik Sarris of the University of Helsinki and colleagues previously noted that the bacteria are present in people with Parkinson’s disease.

In a small study from 2021 They measured the level of bacteria in the stools of 20 with Parkinson’s disease and 20 healthy participants.

Patients with Parkinson’s disease had more bacteria in their samples. A higher concentration has also been associated with more severe disease. A Chinese group found the same thing in March.

In a new study, Sarris and his colleagues examined what happens to roundworms when they ingest Desulfovibrio bacteria. The bacteria were taken from the stools of healthy people or people with Parkinson’s disease.

I think the result is important

Sarris says the finding suggests that bacteria play a role.

The findings indicate that certain strains of Desulfovibrio bacteria are likely to cause Parkinson’s disease. says in a press release.

Charalambos-Tsolis, a professor at the University of Bergen and co-chair of Neuro-SysMed, a center for treatment and research in neurological diseases, disagrees.

Dopamine-producing cells are destroyed

Movement symptoms of Parkinson’s disease are largely due to cells in an area of ​​the brain called the substantia nigra being progressively destroyed. The cells that make dopamine are particularly affected.

Deficiency of the substance causes muscle stiffness, tremors, and slowness of movement.

Scientists don’t know why Parkinson’s disease occurs. But the disease appears to be related to alpha-synuclein, a protein in nerve cells.

He gave bacteria to roundworms

What the researchers did in the new study was remove Desulfovibrio bacteria from the stools of 10 people with Parkinson’s disease and eight healthy people.

They fed the bacteria to small C. elegans worms. C. elegans is a widely used organism in research. You don’t get alpha-synuclein blocks naturally, but have been modified to be able to get them.

The researchers saw that roundworms that received bacteria from Parkinson’s patients had a greater accumulation of alpha-synuclein clumps in neurons, Tzulis explains.

This is also something that happens to people with Parkinson’s disease.

The researchers further noted that roundworms in this group had a higher mortality rate.

It is completely different from a human being

The study is interesting, says Charalampos Tzoulis of the University of Bergen, but one cannot say that bacteria have anything to do with Parkinson’s disease based on this study.

He noted that the researchers used a highly synthetic system to test it.

C. elegans is a simple organism. He does not get Parkinson’s disease, nor do any other animals. In addition, it contains only eight dopamine-producing cells, while humans have hundreds of thousands.

The starting point is a small, microscopic animal unrelated to humans or Parkinson’s disease, says Tzulis.

Whether this finding is significant for people with Parkinson’s disease is not entirely certain.

Take care of the intestines

Overall, research into the relationship between the gut and Parkinson’s disease is a rapidly growing field, Tzulis says. He thinks it is an interesting area of ​​research.

Danish study from 2020 He suggested, for example, that Parkinson’s disease comes in two versions. One starts in the brain and the other in the gut.

The researchers saw that in about half of the patients, neurons were destroyed in the gut and heart before the brain. In other cases, the destruction began in the brain.

The chicken or the egg

Several studies have been done that have shown that patients with Parkinson’s disease have altered the composition of bacteria in the gut, says Tzoulis.

Thus, it has been speculated whether this could be a cause of the disease.

The challenge is that the intestines of people with Parkinson’s disease are affected by this disease.

– Her bowel movement has changed as a result of the loss of gut nerve cells that are part of the disease. So people with Parkinson’s disease essentially experience a change in bowel function compared to healthy people.

It becomes a chicken-or-egg problem, says Tzulis.

It is difficult to determine whether the altered bacterial composition is the cause of the disease or the result of the intestine working differently because of the disease.

The researchers also note that gastrointestinal symptoms appear many years before diagnosis.

Many people had altered bowel movements and slow stomachs for many years before they had problems with the movements.

It is believed that the intestines are affected very early in Parkinson’s disease before their motility is affected.

References:

Vy A. Huynh, Timo M. Takala, Kari E. Murros, Bidhi Diwedi & Per EJ Saris: « Desulfovibrio bacteria promote alpha-synuclein accumulation in Caenorhabditis elegans model of Parkinson’s disease.Frontiers in Cellular and Infection Microbiology, 1 May 2023.

Shiqing Nie, et al: “The link between increased disulfovibrio and disease severity in Parkinson’s disease,” Applied Microbiology and Biotechnology, March 30, 2023. summary.

(This issue It was first published in forcing).