Why Are Autoimmune and Allergic Diseases Rising?

Andrew Wang, MD, PhD, associate professor of internal medicine (rheumatology, allergy and immunology) and immunobiology, studies autoimmune and allergic diseases. His lab seeks to understand the impact of the modern environment on human health.

“Many of the questions that my lab studies have to do with how the nervous system integrates with our immune system and our physiology in general,” he said.

In a Q&A, Wang discusses the increase in autoimmune and allergic diseases, the effects of the modern environment on our immune system, and how his research can help patients.

My mom has lupus, and my older son has food allergies. When I started looking into these diseases, I found that we have a modern epidemic.

In autoimmunity, the immune system attacks your body’s cells instead of protecting them. For example, it can attack your joints, kidneys, or skin as if they were foreign and dangerous. With allergies, the immune system recognizes food or pollen as dangerous and acts like it does when trying to kill a virus or bacteria. These diseases are intimately linked in that the immune system is confused about what is and isn’t safe.

Our genes haven’t changed much in the last 70 years, but our current environment is vastly different.

One dominant idea in the field is called the hygiene hypothesis. People noticed that issues with our immune systems started increasing when we improved sanitation. The thought is that because the immune system doesn’t have much to do in this cleaner environment, it finds inappropriate work in the absence of having to deal with dirt and germs. Some studies show that people who grow up on farms or live in rural areas are less likely to have allergies or autoimmune diseases than people who live in urban areas.

We’re cleaner, but we’ve also added a lot of chemicals and pollution into the environment since the 1950s. The world is very different. For example, we industrialized food, and the chemicals we add to processed foods may be dangerous. The immune system could be recognizing that danger and remembering the food as a proxy for this harmful thing.

We’re also staying awake longer than we used to and worrying more. Some of the previous work out of my lab focused on the effects of psychological stress on immune function. A lot of this was inspired by what patients tell us. For example, they have a stressful life experience—a car accident, bankruptcy, or death in the family—and then their disease flares. My lab’s research has validated our patients’ experiences by showing that stress can activate the immune system.

As a physician-scientist, I hope my team’s discoveries can be translated into clinical medicine to improve patients’ lives. I also hope our work empowers patients with autoimmune and allergic diseases who may have been struggling to find answers about the cause of their conditions.

Yale School of Medicine’s Department of Internal Medicine Section of Rheumatology, Allergy and Immunology is dedicated to providing care for patients with rheumatic, allergic and immunologic disorders; educating future generations of thought leaders in the field; and conducting research into fundamental questions of autoimmunity and immunology. To learn more about their work, visit Rheumatology, Allergy & Immunology.