Senior Investigator Bonnie Dittel, PhD, recently identified a new immune cell subset that helps to dampen autoimmune attacks.
Chances are, if you’ve ever seen a TV commercial for a new drug to treat some sort of symptom, you’ve at least heard of an autoimmune disease, like psoriasis, diabetes or multiple sclerosis. Autoimmune diseases, of which there are more than 100, affect approximately 50 million Americans, and can range from mild to severe. They occur when the immune system, which is supposed to ward off infection and keep you healthy, goes awry and starts attacking healthy tissues.
Autoimmune diseases are often chronic, lifelong illnesses – some with limited treatment options – that can negatively alter people’s lifestyles. Versiti Blood Research Institute immunologist Bonnie Dittel, PhD, has made it her life’s mission to study autoimmune diseases – specifically, multiple sclerosis (MS).
Multiple sclerosis is an autoimmune disease of the central nervous system (brain and spinal cord) that affects more than 2.3 million people worldwide. MS causes inflammation in the brain and spinal cord, leading to inflammatory lesions that contain damaged brain and spinal cord tissue. As different parts of the central nervous system have different functions, the location of these inflammatory lesions can affect the kind of symptoms a person with MS experiences.
Currently, treatments for MS target the immune system and modify the disease course, but they do not stop or cure it. Dr. Dittel is interested in studying the mechanisms behind down-regulating inflammation in the central nervous system, with the hope of developing a universal treatment that can be used for all autoimmune diseases. She believes that B cells are key to accomplishing this.
Over the last 20 years, Dr. Dittel and her team have focused on finding a population of B cells that regulate inflammation. B cells, in general, produce antibodies; for example, vaccines drive B cells in your body to develop antibodies against diseases like the measles. However, there are many different types of B cells with specialized functions, and Dr. Dittel’s goal has been to find the B cells that, instead of contributing to an inflammatory response, keep it under control.
Many patients with cancer currently use a cellular therapy that boosts the body’s immune response and encourages a patient’s own immune system to kill a tumor. However, when it comes to autoimmune diseases, it’s important to do the exact opposite: put the brakes on the immune system and prevent inflammation.
Dr. Dittel was recently published in the prominent medical journal Nature Communications for her discovery of the B cell she has been looking for, which she named BDL. “We identified a new immune cell subset, and that doesn’t happen every day,” she said. BDL interacts with T regulatory cells, or Tregs, which regulate inflammation and are essential to keeping people from developing autoimmune diseases. Tregs fall under the T cell category and, like B cells, there are many different varieties. But over time, these cells’ functions can change, which can affect the immune system.
Alterations in the normal function of the immune system can lead to autoimmunity. Think of Tregs as the guard dogs of the immune system. To keep your guard dogs happy and prevent them from running away, you need to keep them motivated and on the job. If you start with 10 guard dogs but 5 run away, something can potentially sneak past the remaining 5 and invade your property. When that happens, the bad stuff that sneaks in can cause your otherwise tough guard dogs to transform into miniature poodles, which won’t do as well of a job of protecting your property.
That’s where Dr. Dittel’s newly discovered cell BDL comes in. BDL provides the immune system “guard dogs” – the Tregs – with the things they need to stay happy and doing their job. “If you give them great food, even more guard dogs will show up, giving you better protection,” Dr. Dittel says. “That’s what BDL cells do; they keep the Tregs around. They do it by telling them to proliferate.” Without BDL, the number of Tregs will start to decrease. And if a disease like multiple sclerosis is introduced into a compromised immune system, inflammation will linger, permanently damaging tissues and making it difficult to recover.
Finding BDL and learning how they work with Tregs to make sure they’re guarding the body’s immune system was only the first step. Now, Dr. Dittel wants to find a way to use BDL as a universal therapy for patients with all kinds of autoimmune diseases. “We want to be able to leverage what Versiti is already committed to in cell therapies, to develop our therapeutic,” she said. “Our goal is to generate a unique cell therapy that can be used to treat many different autoimmune diseases, not just multiple sclerosis.”
About the expert: Bonnie Dittel, PhD, is a senior investigator at Versiti Blood Research Institute and secondary faculty in the Department of Microbiology and Immunology at the Medical College of Wisconsin.