The human immune system is a complex network of organs, tissues and cells that work together to defend the body from germs, microbes and other foreign organisms that can cause disease. It’s an ingenious system that, when working right, helps protect us from outside invaders, but sometimes it can go haywire and begin attacking our own bodies. When this happens, you’ll develop an autoimmune disease, and currently, more than 80 different autoimmune diseases have been documented in humans.
Although most of these autoimmune diseases are relatively rare, collectively, autoimmune diseases are quite prevalent. According to the National Institutes of Health, more than 23.5 million Americans have an autoimmune disease. Some of the most common are Type 1 diabetes, rheumatoid arthritis, multiple sclerosis, lupus and celiac disease.
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Although not conventionally thought of as an autoimmune disease, chronic obstructive pulmonary disease, a progressive and incurable lung disease that encompasses both emphysema and chronic bronchitis, could have an autoimmune component to it, according to several recent studies conducted at the University of Colorado. Laima Taraseviciene-Stewart, an associate professor at the University of Colorado, has led several of these studies, and says her team has looked at the question from several different angles.
But first, a review of how COPD develops. Inhaling irritants like tobacco smoke or other pollutants or particles such as coal dust leads to lung damage and inflammation. Over time, this damage reduces your ability to breathe and you develop COPD. Meanwhile, the body is trying to fight off these irritants and the immune system is triggered. The body sets off “an inflammatory cascade in the airways resulting in the production of” various immune cells and antibodies, “which play a critical role in the induction of chronic inflammation and subsequent tissue destruction” that are hallmarks of COPD, one review study noted. This complicated series of events and the arrival of these immune cells, although intending to help, can sometimes accumulate and create more damage in the alveoli — the tiny air sacs of the lungs that process air — and the blood vessels of the lungs. This damage, Taraseviciene-Stewart and her team theorized, could be in part due to the action of the body’s immune system being overactivated in responding to these inhaled irritants and attacking itself, so they went looking for the underlying mechanisms that could be at work.
In one study, the team focused on examining the blood, or serum, of animals that had emphysema, and found an association with antigens — foreign substances that can trigger an immune system response — and antibodies — the body’s natural defenders that are sent out by the immune system to fight off those antigens. This would suggest a correlation between the disease and the antibodies, but more work would need to be done before a real connection could be drawn.
Next, Taraseviciene-Stewart says, “we injected endothelial cells [cells from the interior surface of blood or lymphatic vessels from animals that had emphysema] and some animals developed antibodies” in response to those foreign cells being introduced to their bodies. Further, “if you inject serum or you transfer the immune cells from these emphysematous animals to healthy animals, you can induce emphysema in the healthy animal. This was the first study that showed that antibodies caused emphysema,” she says.
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Yet another study conducted in Spain in 2010 also found an autoimmune component to COPD. That study, which involved looking at blood samples from 328 patients with “clinically stable COPD,” found that between 26 and 34 percent of these patients had abnormal levels of circulating antinuclear antibodies and antitissue antibodies, two markers of autoimmune disease. The research concluded that these findings supported the idea that autoimmunity plays a role in the development of COPD for some people.
However, all this data seems to be pointing to the idea that COPD likely has an autoimmune component for some patients, but not all, which suggests that there could be different variations of the disease. Taraseviciene-Stewart says these findings are “very important,” because as additional work is done and the triggering antigens are identified, scientists may be able to better diagnose the various diseases that we currently think of as COPD. Currently, a COPD diagnosis encompasses both emphysema and chronic bronchitis, but those two diseases and perhaps others that have slightly different development origins or mechanisms could eventually be teased out from our current understanding of COPD. This more precise pinpointing of the specific diseases that manifest with essentially the same symptoms may lead to better diagnostic tools and more targeted treatments.
“I think down the road, hospitals or universities, one way or another, will develop something that you can test for the autoimmune disease, for antigens or for antibodies that can differentiate between these diseases. If we could develop a panel of antigens, and could screen and differentiate the diseases, it would be very helpful for the therapy, because with the therapy, it’s very important to know the source. If you know the source of the antigen, then it’s very easy to treat the patient,” Taraseviciene-Stewart says.
In addition, she says that as we learn more about the effects of pollution on the lungs, and as electronic cigarettes — which she says “are just as harmful as tobacco cigarettes” — continue to gain in prevalence, it’s important to understand the science of how COPD develops in the first place. These autoimmunity findings could also lead to a better understanding of whether and how allergies in children could be a contributing factor for the development of COPD later in life. “There’s more and more allergies in kids, and it could be that allergies could develop into the autoimmune disease,” she says.
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So, does that mean people who already have one autoimmune disease are at higher risk of developing COPD? Maybe, but not necessarily, says Taraseviciene-Stewart. “We don’t have the yes or no answer, but it is quite possible.” In general, people who have one autoimmune disease are at higher risk for developing another, as the overactive immune system finds multiple ways and places to attack the body. One study said that “about 25 percent of patients with autoimmune diseases have a tendency to develop additional autoimmune disorders,” while another found that between 4 and 5 percent of people with autoimmune diseases have more than one.
As scientists and researchers continue to delve into the specific series of changes in the body that lead to COPD, a better understanding of — and hopefully better treatments for — this chronic and incurable lung disease may emerge.
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Does COPD Have an Autoimmune Component? originally appeared on usnews.com
