The immune system is a complex and powerful system of the body that works to defend it from infections. But when it comes to multiple sclerosis and other forms of autoimmune diseases, it does the exact opposite and turns on its own body.
In this article, we will take a look at the complex relationship between the immune system and the autoimmune disease multiple sclerosis, popularly known as MS. While no one knows the cause of MS, what they do know is that it’s simply explained as a disease that causes the immune system to attack its own tissues.
According to the Mayo Clinic, MS is explained as ‘a potentially disabling disease of the brain and spinal cord (central nervous system).’ When someone is diagnosed with MS, their immune system attacks the myelin, or the protective sheath that covers nerve fibers or axons, as they are otherwise known. When this happens, it causes communication issues between a person’s brain and the rest of their body. When the axons are damaged, they affect the brain, spinal cord and optic nerves as well.
When MS attacks – which are also called exacerbation – it causes scar tissue as a result. This also becomes visible in the white and gray matter of the brain. The attack is what causes the various immune cells to damage or destroy the myelin in the area that’s being attacked.
While experts refer to MS as an autoimmune disease, the scientific community share that their study, on the other hand, has not identified any MS-specific antigens which are the proteins that cause the immune system to attack.
While there are still so many unknown factors when it comes to MS, there are some things that we do know about the immune system and the role it plays when it comes to multiple sclerosis.
Autoimmunity and How It Attacks the Wrong Side
A person’s T cells are a vital part of the immune system. With MS, they become activated in the lymph system and through blood vessels, and end up entering the central nervous system (CNS.) After which, they release chemicals that causes the kind of damage known for this disease in particular, as well as activating B cells and other forms of immune system cells that end up attacking as well.
But what scientists cannot explain is what actually triggers the immune system to go off balance, or what’s causing the T and B cells to activate in the first place.
Many experts share that particular conditions like RA, lupus, celiac disease, type 1 diabetes and MS are all examples of such autoimmune diseases ‘that are associated with the production of autoantibodies and self-reactive T cells.’
Meanwhile, the immune response in other so-called self-antigens are not a feature with such diseases as inflammatory bowel disease, psoriasis, or ankylosing spondylitis, despite the fact that they involve the immune system as well.
But the main concern and question that researchers are attempting to address here is, when it comes to MS, what could stop the T cells from self-activating to prevent them from attacking the central nervous system (CNS)?
What Causes the Immune System to Attack?
In order to figure out how to limit or stop the T cells from attacking, the research team first tried to figure out why they attack the central nervous system at all.
According to the National Institute of Neurological Disorders and Stroke (NINDS), there are a few theories on why it happens.
As for the first theory, they share that ‘when the immune system is fighting an external invader – such as a virus – that mimics components of the brain, the immune system attacks CNS myelin in its attempt to quash the invader, a process known as molecular mimicry.’
The next theory is that the immune system believes that the brain cells are unhealthy so it attempts to destroy them.
Meanwhile, another theory is that the immune system accidentally misconstrues normal brain cells as foreign invaders, which causes it to attack.
As for another theory, due to the blood brain barrier (BBB) which is what keeps the spinal cord and brain separate from the other substances in the body, which includes the immune system, when there is a rupture or crack in the barrier, it allows the brain to be exposed to the immune system. Experts believe that when this occurs, the immune system could see myelin as a foreign invader, attacking it in the process.
What About Viruses and MS?
Although the cause of MS is still unknown, research has revealed that its origins are mostly due to ‘both genetic predispositions combined with environmental factors.’ Due to this, the link between MS and other infectious agents and viruses due to environmental factors are highlighted.
Notably, there are a number of different viruses usually found in those diagnosed with MS, yet Epstein-Barr virus (EBV) is the one that is frequently linked to this autoimmune disorder.
EBV is described by the Centers for Disease Control and Prevention (CDC) as “human herpesvirus 4, is a member of the herpes virus family.” It is considered one of the most common of human viruses on the planet, and is the cause of infectious mononucleosis, which is more commonly known as mono.
Statistically, it is said that only around 5% of the population has not gotten this virus. Meanwhile, those that have yet to contract EBV are considered lower risk when it comes to developing MS than individuals that have had it. Moreover, people that got EBV in their early childhood are also at substantially lower risk of developing MS than those that didn’t get EBV until they were in adolescence or adulthood.
The report claims that getting the virus later on in life tends to come with a more intense immune response to the virus. Researchers explain that the higher MS risk could be due to the kind of EBV immune response that leads towards MS, and not because of the virus infection alone.
Yet, it’s important to understand that a lot of these findings are still under scrutiny since there is still no viable proof that MS is caused by EBV. In addition, the scientific community says that they still don’t completely understand the increased risk of MS due to the virus.
Treatment and Trials for the Immune System
Since MS is an autoimmune disease, there are a number of treatments in place that target the immune system particularly.
One treatment is known as beta interferon. As explained by Drugs.com, “Interferons are proteins produced by tumor cells or host cells that are infected with viruses, bacteria and other unknown nucleic acids. Interferons also activate other cells that serve as part of the immune system and destroy invading pathogens.”
At the beginning of an immune response, white blood cells release gamma interferons, which causes inflammation in the tissues that are being attacked. However, beta interferon is usually released during the tail end portion of an immune response, and therefore blocks gamma interferons and helps lessen the inflammation.
Beta interferon drugs can reportedly lessen the number of MS attacks or exacerbations, which slows down the growth of the disease as well. Another plus is that when the exacerbations happen, this type of treatment can also shorten and lessen the severity of the attack.
Another type of treatment by NINDS is a stem cell form of treatment called BEAT-MS, but it is still undergoing a clinical trial. This trial involves researchers removing the immune cells from participants of the experimental trial and infusing some of their own. The hope is that their stem cells will cause a reset in the participants’ immune systems to stop them from attacking the CNS.
Could the Immune Cells in a Person’s Gut Be the Answer?
Recently, a number of studies have been focusing on the role of microbiome in immunity, and as for MS research, they are looking into minutiae of gut bacteria. One such research team has collected samples of blood, stool, and spinal fluid from individuals with MS, those without, and others that have different disorders.
What they found is that when a person with MS has an exacerbation, the immune cells that react to particular gut bacteria actually move from the gut to the brain during the attack, possibly helping protect the brain and reduce any inflammation.
A study on this was released in Science Immunology. It showed that after looking at the brain tissue of patients with MS, ‘showed that specific B cells targeted certain strains of gut bacteria linked to MS inflammation.’
The research group also shared that they observed how during MS attacks, and not during remissions, the ‘B cells traversed the BBB to MS brain lesions, releasing messenger chemicals that aim to reduce inflammation.’
While the study authors explain that it’s not yet clear what exactly activate the B cells to travel to the brain in what is a ‘protective mission,’ but if they can figure out what activates the process, it could potentially lead them to a way to treat MS.
Lead researcher, Dr. Anne-Katrin Pröbstel, “Apparently, these immune cells migrate from the intestine to the inflammation sites in the central nervous system, where they release an anti-inflammatory messenger substance. That could explain why the illness worsens if these immune cells are removed from the blood with medication.”
The Possible Silver Lining
According to multiplesclerosis.net, in the United States alone, around 750,000 to 1 million people over the age of 18 have MS, with millions of others around the world as well. Research teams and scientists are continually at work, attempting to get a better grip and understanding of this difficult and debilitating disease, as well as coming up with new treatments.
But one possible silver lining is that in a number of studies, there is one particular thing that has been incredibly beneficial to all patients, and that’s the sun.
In fact, NINDS claims that studies have shown how those with higher levels of vitamin D and those who are in the sun more are less likely to be diagnosed with MS.
For those with MS, it also equates to patients having less severe forms of MS, as well as less relapses, than those with less vitamin D.
While research tells us that sunlight is one way to help human skin create vitamin D, researchers also believe that taking vitamin D supplements can also help modulate the immune system while reducing the risk of MS and other autoimmunity diseases.
In the meantime, studies and research into what causes MS, as well as trials and novel treatments continue to grow in the hopes that scientists and researchers will find ways to further help patients that suffer from MS, as well as positively improve their quality of life.
One such patient living with secondary progressive MS said during an interview in a study published in BMJ journalsexplains their situation as, “[I]t’s like living your life with a weight on your back all the time, we can’t do, we can’t plan anything.” And it’s comments like these that make researchers work harder to gain answers to such troubling autoimmune disorders like this.