Experts still do not know the root of Parkinson’s disease (PD). Science has found that this movement disorder is caused by a combination of environmental and genetic factors. Most people with PD first develop the disease after age 60.
Despite uncertainties regarding the cause of PD, research over the last several years points to dysfunctions in the immune system. It’s still not clear whether PD can be considered an autoimmune condition.
Immune cells defend the body from outside invaders like toxins or germs that can cause infection. These outside substances that can harm the body are called antigens.
When the immune system detects an antigen, the normal immune response is to promote inflammation and produce small proteins called antibodies. The inflammatory reaction from the body helps to get immune cells moving, encouraging them to fight bacteria, respond to toxins, and heal injured tissue. Antibodies that recognize different types of antigens can bind with and neutralize their targets.
When the immune response becomes dysfunctional and starts to attack your tissues and cells, this is an autoimmune response. When an inflammatory reaction against your body becomes long term, autoimmune disorders can result.
In 2017, a study conducted at Columbia University Medical Center reported the first evidence that PD may be partially an autoimmune disease. Read on to learn about the process by which the researchers think Parkinson’s may develop.
Protein in the brain called alpha-synuclein misfolds, then starts to build up in structures called Lewy bodies in brain cells that make dopamine. This abnormal process is called aggregation. This aggregation of alpha-synuclein tricks the immune system, causing it to produce a T-cell response.
These T cells engage in an autoimmune attack against the alpha-synuclein in brain cells, specifically in parts of the brain like the substantia nigra. This autoimmune response can occur in the neurons (brain cells) of those with PD. It does not appear to happen inside the bodies and brains of healthy controls.
As people age, their bodies may struggle to break down and recycle protein like alpha-synuclein. This buildup may continue to trigger the autoimmune disorder in their brains, possibly playing a role in the progression of PD.
In 2020, another study at La Jolla Institute for Immunology examined blood samples from people with PD and those without the disease. They confirmed the same T-cell response to alpha-synuclein in people with PD — especially during the early stages of this movement disorder.
If these theories are proved true, they may affect the way PD is diagnosed and treated in the future. Blood samples can provide evidence of autoimmune responses against alpha-synuclein in people with PD. This finding could pave the way for blood tests to diagnose PD and may be especially helpful in the early stages of Parkinson’s.
One day, researchers may be able to check people for genetic biomarkers for PD. This type of test could predict whether a person has a risk factor for developing autoimmune attacks on alpha-synuclein. It may even help with early diagnosis, detecting PD before it starts causing motor symptoms.
Nonetheless, before tests like this become available, large and long-term studies must provide scientists with evidence that monitoring an autoimmune reaction in a person’s body is a good test for PD.
Researchers have studied how they may use the immune system to treat PD in the future in an approach called immunotherapy, although this is still experimental. Scientists hope to one day be able to slow the disease progression.
Scientists have investigated sargramostim (Leukine), a drug that works by stimulating immune cells, as a potential treatment for PD. Although approved by the Food and Drug Administration (FDA) for people recovering from cancer therapies and bone marrow transplants, sargramostim has shown moderate improvement in studies of the T-cell response of people with PD.
Researchers are also now discussing using monoclonal antibody therapy to target alpha-synuclein and possibly slow the progress of Parkinson’s.
In another study, researchers in neurology looked at the link between medications that suppress the immune system and the risk of PD. They found evidence that using corticosteroids and other immune system blockers may help lower the chance of developing Parkinson’s.
Despite these promising initial findings, more research is needed to understand the connection between PD and autoimmunity. This information will provide better ways to diagnose and treat PD going forward.
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