Autoimmune Diseases Versus Immune-Mediated Inflammatory Diseases

In our four-part series of interviews with gastroenterologist Dr. Neilanjan Nandi, he will be answering patient questions on all-things IBD. Next up is Jaime Holland. She's been living with Crohn's for over 20 years, and asks Dr. Nandi questions about IBD treatments and the immune system.

Autoimmune versus immune-mediated: Which is Crohn's?

Jaime first asks Dr. Nandi about the confusion around how Crohn's is classified. "There is a misconception about IBD being an autoimmune disease ... when it is more 'immune-driven.' Can you give me that explanation?"

Dr. Nandi explains that this is really just a technical difference. Autoimmune means that the body has made antibodies to a component of its cells. These antibodies are directed at a cell, or a protein, or some part of the actual anatomy. They're autoantibodies. And they can be detected in autoimmune illnesses.

But in Crohn's, autoantibodies have not been found. While a blood test might show antibodies to a different type of bacteria or yeast, and these may be associated with the possible development of inflammatory bowel disease, these are not autoantibodies. They are antibodies to other things swimming in the bloodstream.

And while these antibodies may be an indicator of IBD, Dr. Nandi says they don't provide a completely accurate diagnosis. "We don't hang our hat on those tests to make a diagnosis," Dr. Nandi says. Ultimately, autoantibodies have not been found in the diagnosis of IBD patients.

How important is the distinction?

Crohn's is not an autoimmune disease, but it is immune-mediated. So what's the difference? According to Dr. Nandi, not much.

"I know in academic circles we debate it. Do I think [the difference] is important enough to harbor on in patient conversations? Probably not," he says. "Because we’re going to treat it the same."

Dr. Nandi went on to explain how the immune system attacks a part of the body in Crohn's patients. With many complex factors at play, it all comes down to how the immune system is programmed, and how it is triggered to attack the gut.

"We treat these immune illnesses with, in many ways ... the same concepts," Dr. Nandi says. "[Treatments] of immune blockade, biologic antibody medications, or small molecules that inhibit hormones called cytokines from wreaking havoc in the gut."

So when it comes to autoimmune versus immune-mediated? "It's a technicality," he says.

What about immunosuppression?

Jaime brings up another topic that's been gaining traction in the IBD community amid COVID-19. She said there is concern around being immunosuppressed due to being on a biologic. Jaime asks, "How immunosuppressed are we with just being on a traditional biologic?"

Dr. Nandi goes on to explain that a biologic medication, put simply, is an antibody that blocks one focal portion of the immune system, not the entire immune system. It targets one mechanism of fighting off an infection. He said that results in a lower risk of infection than steroids, such as prednisone, which is actually far more immunosuppressive.

"Our immunosuppression is all relative," Dr. Nandi says. "Prednisone: high risk of immunosuppression. Biologics: targeted, focal therapy. They suppress a portion of the immune system while letting the rest of your immune system function. So they’re much safer drugs."

To hear more from Dr. Nandi, listen to the full interview.