Parkinson's disease is a neurodegenerative disease that affects a lot of people worldwide with an estimated figure of about 1 million in the United States alone, according to the National Parkinson’s Foundation. Despite the sheer amount of support available for patients as seen in the dozens of support groups, organizations, associations, and advocacies for the disease, the underlying causes of Parkinson's and its potential cure remain to be unknown. Fortunately, with the continuing fundraising activities and active research in the medical community, patients and their loved ones are given new hope upon the discovery of a triggering enzyme that can potentially provide medical professionals with a clue in developing a cure for Parkinson's disease. Read on below to know more about this uplifting discovery.
Parkinson's may have originated from the gut
A study made earlier this year by a group of Swedish researchers led by Dr. Karin Wirdefeldt that was published in the journal Neurology discovered more evidence that Parkinson’s disease may originate from the digestive system. The study of Wirdefeldt’s group involved following around 377,000 people over a period of five years, 9,430 of these individuals having a medical history of surgically removed vagus nerves, a procedure often done to treat illnesses such as an ulcer. According to Wirdefeldt, patients with the main trunk of their vagus nerve intact or only had a selective removal of their vagus nerve with the main trunk still essentially intact, were more likely to develop Parkinson’s disease than those who had it surgically removed.
Findings also suggested that subjects who had their vagus nerve removal at least five years prior were the least likely to develop Parkinson’s disease by 40%. The vagus nerve is a nerve that originates from the base of the brain or the brain stem and extends all the way down to the abdomen, making it in close proximity of the digestive system. The researchers believed that Parkinson’s, as it develops into the gut, enters the brain through the vagus nerve and messes up some brain functions, leading the patient to exhibit the typical symptoms of Parkinson’s disease such as stiffness, shaking, sluggish movement, and poor balance.
Digestive system problems prior to Parkinson's disease
Another study that supported the Swedish researchers’ proposition is the observation of a group of researchers from the California Institute of Technology. They noted that Parkinson's patients often reported gastrointestinal problems as far back as ten years prior to experiencing the manifestations of Parkinson's disease. This theory further led them to believe that gut bacteria among Parkinson's disease patients is slightly different from those who do not suffer the condition. To prove the validity of their statements, the group genetically-modified some mice to overproduce alpha-synuclein and divided them into two groups.
One group of mice was exposed to a germ-free and sterilized environment, while the other group was exposed to a normal non-sterilized environment. Both groups of mice were subject to several tests involving brain and motor functionality. Surprisingly, the mice who were exposed to the normal, non-sterilized environment soon exhibited signs and symptoms of Parkinson’s disease. Meanwhile, the other group of mice who were living in a germ-free, sterilized environment did experience a decline in motor functions and brain activity, but their progression into Parkinson’s disease happened at a much later time as compared to their peers in the normal, non-sterilized environment. Furthermore, the researchers detected a significantly greater amount of alpha-synuclein in the second group’s brains as compared to those mice in the germ-free, sterilized environment.
Alpha-synuclein Protein and Lewy Bodies: Potential culprits of Parkinson’s disease
Prior studies have noted the involvement of a certain protein called alpha-synuclein, a potential cause of Parkinson’s disease. Alpha-synuclein is a mysterious protein present in copious amounts in the brain whose normal functions in the human body is still a mystery to researchers up to this day. Alpha-synuclein, for some reason or another, has the tendency to bundle up with other alpha-synuclein protein fibers to form Lewy bodies. Lewy bodies, according to Dr. Keqiang Ye, are highly neurotoxic particles, which is why their presence in the brain can lead to cell death and consequently, the development of Parkinson’s disease. The same scenario is also present in Alzheimer’s disease, wherein a certain protein named tau gets entangled around nerve cells, cutting off the cell’s reception of nutrients and eventually resulting in the nerve cell’s death.
The cleaving effect of asparagine endopeptidase
Asparagine endopeptidase is an enzyme found in human cells that is responsible for a couple of biological processes such as normal kidney functions and homeostasis, or the regulation of certain biological mechanisms such as temperature and water levels in the blood. While present in trace amounts in a non-Parkinson’s patient’s cells, a study made by a group of researchers led by Dr. Keqiang Ye found that asparagine endopeptidase is present all over cells in a Parkinson’s disease patient. Upon further study, the group found that asparagine endopeptidase, when in contact with alpha-synuclein in the brain, brings forth a “cleaving” or shearing effect to the protein. The “cleaved” alpha-synuclein fibers later clump together to form Lewy bodies that will soon start to affect the normal functioning of nerve cells. Dr. Ye’s group noted that Lewy bodies formed from “cleaved” alpha-synuclein are more neurotoxic as compared to Lewy bodies from “uncleaved” alpha-synuclein protein fibers. However, since the tests involved in the study were made on animals, particularly mice, Dr. Ye noted that asparagine endopeptidase might not be the only culprit in the formation of neurotoxic Lewy bodies since the said enzyme is not the only one in the body that can cleave through alpha-synuclein protein fibers. Additionally, the results presented by the animal tests may not produce identical results when done on humans.
Recent attempts at developing a cure for Parkinson’s disease
With the findings above, several organizations that push for Parkinson’s disease research have pooled together resources to encourage biotech companies to start developing a cure for the disease. Currently, a vaccine-type cure is in the works by an Australian biotech company named AFFiRiS. The product is designed to bind together alpha-synuclein protein fibers in the brain and clear them from the brain afterward. The potential cure is still in its initial stages of clinical testing.
Aside from the vaccine, other biotech companies are also working on approved compounds known to slow down, halt or break off the formation of Lewy bodies among Parkinson’s patients. These potential remedies are still undergoing preclinical testing to prove their effectiveness.
The implications of these recent developments in Parkinson’s disease research
The new developments above are proof that the fight against Parkinson’s disease research is far from over. While they contribute something to humanity’s knowledge about the disease, the findings can also aid future researchers in their studies by providing them a definitive focal point for their prospective studies. Biotech companies that develop the cures are also given more clues to the nature of the ailment and can begin experimenting with various compounds and substances that can ward off the disease. Finally, these discoveries aid people with Parkinson’s disease and their families and friends by giving them a new sign of hope that a cure indeed exists. Hopefully, the current incurable status of Parkinson’s disease may as well change sometime soon.
- A study made earlier this year by a group of Swedish researchers led by Dr. Karin Wirdefeldt that was published in the journal Neurology discovered more evidence that Parkinson’s disease may originate from the digestive system.
- The California Institute of Technology noted that Parkinson's patients often reported gastrointestinal problems as far back as ten years prior to experiencing the manifestations of Parkinson's disease.
- Prior studies have noted the involvement of a certain protein called alpha-synuclein, a potential cause of Parkinson’s disease.