This article was originally published in June 2020 and has since been updated.
In a healthy individual, the body’s immune system is there for protection- it attacks invaders and destroys pathogens. An autoimmune disease occurs when this system makes a mistake, and instead attacks healthy cells.
There are more than eighty different types of autoimmune disorders, and a person can have more than one at the same time. Some of the more well-known autoimmune diseases include celiac disease, multiple sclerosis (MS), rheumatoid arthritis, and diabetes [1].
An allergy is similar to an autoimmune disease, except instead of attacking healthy cells in the body, the immune system is attacking a foreign substance such as pollen or bee venom that doesn’t normally produce a reaction in most people [2].
While allergies can often be treated, most autoimmune diseases remain incurable. Recently, however, there has been a break-through. Researchers have now conducted experiments that have successfully switched immune cells from attacking the body to protecting it.
How Does the Immune System Work?
Before we can understand the experiments these researchers have done, we must first have a better understanding of how our body’s immune system actually functions.
In order for the immune system to successfully defend our bodies against foreign invaders like bacteria, viruses, parasites, and cancer cells, it must be able to distinguish what belongs in the body (referred to as “self”), and what does not (referred to as “foreign” or “non-self”).
Antigens are substances that are produced by pathogens. When they are perceived as dangerous by the immune system, the body will mount a response to attack and destroy those foreign cells [3].
The primary way the immune system does this is by multiplying the number of T cells in the body. A T cell (T lymphocytes) is a white blood cell that is responsible for the adaptability of the immune system. They are the “seek and destroy” cells that can target and destroy specific invaders [4].
T stem-cells, which are essentially immature T-cells, go to the thymus gland in the neck to mature and differentiate into various forms of T-cells. They then become active in the immune response.
Normally, T-cells that are potentially activated against the body’s own tissues are killed or changed (often referred to as “down-regulated”) during the maturation process [4].
T-cells remain in a resting state until they are needed to mount an immune response. When immune response genes are activated, T-cells multiply and attack. Once the foreign invader is destroyed (the infection is over), some of these T-cells remain and become memory T-cells, giving the body lifelong immunity to that pathogen [5].
How do Autoimmune Diseases Happen?
Occasionally, the immune system makes a mistake, and recognizes the body’s own cells as non-self or foreign. For example, in the case of MS, the T-cells recognize myelin basic protein, which is the insulting coating on the outside of nerve cells, as foreign.
As such, the T-cells begin attacking the nervous system, which causes individuals suffering from MS to lose control of their muscles [5].
The exact cause of autoimmune diseases remains a mystery. There are people whose genes make them more susceptible to autoimmune disorders, and one theory is that certain microorganisms, like viruses or bacteria, or even some drugs may trigger changes that confuse the immune system. If your genes already make you more prone to autoimmune diseases, this is more likely to happen to you [1].
Autoimmune Experiments: Switching Immune Cells
The immune system is regulated by two types of genes: one that tells the immune system to attack, and one that silences it to prevent it from going out of control. The researchers showed that the genes that are responsible for suppressing the immune system can be reprogrammed at the chromosomal level to keep them more active, by making T-cells more tolerant.
The end result is that the signal inside T-cells that would normally turn on other genes and activate the immune system is weakened. This means that T-cells stop getting the signal to attack the body’s healthy cells.
The researchers who conducted this experiment focussed on T-cells that specifically recognize myelin basic protein as an antigen (as is the case with MS). They found that when they gradually exposed the T-cells to increasing levels of myelin basic protein, the signals telling the T-cells to attack became weaker,and converted them from attacking to protecting [6].
A Life-Changing Experiment
This experiment could have a profound impact on the lives of individuals suffering from autoimmune diseases. Currently, autoimmune diseases are treated using immunosuppressive drugs. The problem with this type of treatment is that it’s non-specific, meaning it suppresses the entire immune system, not just the specific T-cells that are attacking the wrong cells.
Patients who are taking immunosuppressive drugs become more prone to cancers and other infections because their entire immune system is being weakened. This antigen-based therapy would allow doctors to treat only the T-cells that are responsible for the mistake without making the patient more prone to other infections and diseases.
“One day we hope that antigen-based immunotherapy will be able to deliver major benefits for all types of autoimmune disease,” said the researchers. “By detailing the complex mechanisms that control the fate of self-reactive T cells, we may have also opened the door for more specific therapies for these diseases.” [5]
Trials are still underway for this therapy in patients with MS and grave’s disease, but short-term results have been very promising and patients participating in the trials have been showing improved health [5].
Read: Autoimmune Diseases Like Rheumatoid Arthritis Could Begin in Your Fridge
Sources
- “Autoimmune disorders.” Medline Plus
- “Allergies.” Mayo Clinic
- “Overview of the Immune System.” Merck Manual. Peter J. Delves
- “Autoimmune Experiments Switch Immune Cells From Attacking The Body to Protecting It.” Science Alert. Peter Cockerill and David C. Wraith, The Conversation. June 22, 2020
- “Chromatin Priming Renders T Cell Tolerance-Associated Genes Sensitive to Activation below the Signaling Threshold for Immune Response Genes.” Cell. Sarah L. Bevington, et al. June 9, 2020.