The use of appendicitis
Appendix removal reduced the risk of developing Parkinson's disease
Ekaterina Rusakova, N+1
Appendix removal reduces the risk of developing Parkinson's disease by 19 percent, according to Science Translational Medicine (Killinger et al., The vermiform appendix impacts the risk of developing Parkinson's disease). At the same time, the risk for rural residents is reduced by 25 percent. In the appendix, even in young people, aggregates of the α-synuclein protein accumulate, which increase the risk of this disease.
Aggregated α-synuclein in appendix neurons
Viviane Labrie / Van Andel Research Institute
However, about one percent of the population suffers from Parkinson's disease, and the pathogenic form of the protein was found in the tissues of the appendix in most people from the sample, so in addition to α-synuclein, other, still unknown factors obviously affect the development of the disease.
Parkinson's disease is an age-related neurodegenerative disease characterized by motor disorders such as tremor, stiffness of movements. The disease is caused by the death of dopamine-producing neurons in a part of the brain called the black substance. In Parkinson's disease, Levi's corpuscles accumulate in the brain – inclusions consisting mainly of insoluble aggregates of the α-synuclein protein, the presence of which leads to the death of neurons.
It is now known that this disease is characterized not only by motor disorders, but also by other dysfunctions, including deterioration of the gastrointestinal tract (gastrointestinal tract). Moreover, it can begin 20 years before the development of Parkinson's disease and the appearance of motor disorders. At the same time, an aggregated form of α-synuclein is formed in the intestinal neurons, which presumably affects the occurrence of pathology in the brain. Like prions, α-synuclein in pathogenic form is able to penetrate into neighboring cells and cause the formation of Levi's bodies. Some studies have shown that dissection of the vagus nerve trunks (which goes from the brain to the abdominal cavity) leading to the stomach and intestines reduces the risk of developing Parkinson's disease. Since α-synuclein accumulates in the neurons of the enteral nervous system long before the onset of symptoms of the disease, and the rupture of the pathway leading from the stomach and intestines to the brain reduces the risk of developing the disease, some researchers believe that the disease begins in the gastrointestinal tract.
As it has been shown, α-synuclein in pathogenic form is formed in the appendix both during Parkinson's disease and in healthy people. American and Swedish researchers led by Viviane Labrie from the Van Andel Research Institute suggested that the accumulation of the aggregated form of α-synuclein begins in the appendix, and its removal can reduce the likelihood of developing the disease. To test their hypothesis, the scientists analyzed data from the Swedish National Patient Registry and the collaboration "Initiative to Identify Markers of Progression of Parkinson's Disease". The National Patient Registry has records of 1.698 million people, including 551 thousand people who had their appendix removed. The health status of some patients was monitored for 52 years. From the collaboration database, the authors of the study took detailed information about the diagnosis of 849 patients, the age at which the disease began to progress, demographic and genetic data.
The results of the analysis of data from the Swedish National Patient Registry showed that the removal of the appendix (appendectomy) reduces the risk of Parkinson's disease by 19.3 percent. In people living in rural areas, the risk of developing the disease decreased even more – by 25 percent. At the same time, if patients underwent appendectomy 20 or more years ago, and they still had Parkinson's disease, the diagnosis of a person was made, on average, 1.6 years later than those who did not have their appendix removed.
Analysis of data from the collaboration "Initiative to identify markers of progression of Parkinson's disease" showed that if a person had an appendectomy 30 years or more before the onset of the disease, it allowed to delay the onset of the disease, on average, by 3.6 years.
In addition to statistical analysis, the scientists tested the presence of a pathogenic form of α-synuclein in the appendixes of 48 people aged zero to 84 years who did not have Parkinson's disease. They took samples of appendix tissues after surgery, treated them with an enzyme that cleaves free α-synuclein, but leaves the protein intact in an aggregated, insoluble form, and looked to see if there was any in the appendix tissue. It turned out that the pathogenic form of α-synuclein was in the tissues of the appendix of 46 out of 48 people. The researchers also checked that α-synuclein in an aggregated form is also present in the tissues of the appendix in six people suffering from Parkinson's disease.
"We were surprised that the pathogenic form of α-synuclein was so widespread both in healthy people and in patients with Parkinson's disease," says Vivian Labrie. "It seems that these aggregates, although toxic to the brain, are quite normal for the appendix. This suggests that their presence alone cannot be the cause of the disease. Parkinson's disease is relatively rare, less than one percent of the population, so there must be some other mechanism or coincidence of events in which the appendix begins to influence the development of the disease. This is what we plan to investigate in the future: which factor or factors shift the balance towards the development of the disease."
Earlier, Japanese doctors proposed treating Parkinson's disease with pluripotent stem cells, from which the precursor cells of dopaminergic neurons are obtained. The researchers conducted successful tests on rhesus monkeys with a model of this disease, and this summer they launched the first clinical trials involving humans.
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