November 6, 2013
News Review From Harvard Medical School -- Abnormal Antibodies Precede Sjögren's
Abnormal antibodies are found in some people with Sjögren's syndrome years before symptoms appear, a new study finds. Sjögren's syndrome is an autoimmune disease. As in other such diseases, people with this condition have abnormal antibodies that attack parts of the body. These are called autoantibodies. In the case of Sjögren's syndrome, they attack organs that produce lubricating fluid, such as tears. The new study focused on 44 people with Sjögren's syndrome. All of them had given blood samples, for unrelated reasons, 4 to 6 years before they started having symptoms of Sjögren's. Researchers tested the blood. They found autoantibodies in 29 out of 44 samples. These results were compared with an otherwise similar group of people who did not have Sjögren's. Some people in this group also had autoantibodies in their blood. However, they were found 4 to 15 times as often (depending on the type) among people with Sjögren's. The Journal of the American Medical Association published the study November 6.
By Robert H. Shmerling, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
Autoimmune diseases are fascinating and poorly understood conditions. They are also a source of much suffering and early death for millions of people worldwide.
And there are hundreds of them. They are linked to each other by the way they start: a "misfiring" of the body's immune system. Common examples of autoimmune disease include lupus, multiple sclerosis and type 1 diabetes.
Immune cells are supposed to keep the body healthy. They do this by attacking and removing bacteria, viruses, toxins and other triggers of disease. But with autoimmune disease, immune cells mistakenly attack parts of the body instead. It's like having your guard dog turn on you for no apparent reason.
Each autoimmune condition has its own unique features. This one attacks the brain, that one goes for the lining of the intestines, and yet another damages the joints or skin. The reason for the abnormal immune function is usually unknown. A common theory is that something in the environment triggers the abnormal immune response. The trigger could be an infection or a toxin, for example. It's thought that this occurs in a person whose immune system is genetically prone to such problems.
One of the ways the immune system runs amok is by making abnormal antibodies. Antibodies are proteins that grab onto microbes until other immune cells can come in for the kill. In autoimmune disease, "autoantibodies" are produced and attach to normal cells or tissue. In some conditions, these antibodies are the actual cause of disease. Anti-DNA antibodies in people with lupus are one example. In other conditions, the autoantibodies show that something is amiss with the immune system. However, they don't actually cause disease. The "rheumatoid factor" in rheumatoid arthritis is an example.
A new study examines autoantibodies in people with Sjögren's syndrome. Sjögren's syndrome is an autoimmune condition in which immune cells attack glands that produce saliva and tears. As a result, dry eyes and dry mouth are cardinal features of this condition.
In this new study, researchers tested blood samples of 44 people with Sjögren's syndrome. The samples had been provided an average of 5½ years before symptoms began. In two-thirds of these cases, autoantibodies were already present. In at least one case, the antibodies were present 18 years before symptoms began.
Similar findings have been made in people with conditions closely related to Sjögren's syndrome, including rheumatoid arthritis and lupus.
These findings are interesting and should be helpful to researchers trying to understand how Sjögren's begins. But in the short-run, at least, it's not clear how useful this discovery is. For people who have no symptoms, testing for autoantibodies is unlikely to lead to treatment. Many -- or even most -- people who have autoantibodies never develop disease. And the medicines used to treat autoimmune disease can have major side effects.
So I think the authors of the study are right when they say "the significance of these … autoantibodies for determining prognosis and treatment remains to be determined."
What Changes Can I Make Now?
As is true for most autoimmune diseases, the cause of Sjögren’s syndrome is unknown. As a result, there are no known measures you can take to avoid this condition.
Even with the results of this study, there is rarely a reason to search for autoantibodies in people who have no symptoms. False-positive results (abnormal results in people who have no disease) are common. So such a "fishing expedition" would likely do more harm than good. And there is no treatment that would be recommended on the basis of having the autoantibodies alone.
However, if you do have symptoms, let your doctor know about it. Symptoms of Sjögren's syndrome include:
- Dry eyes
- Dry mouth (which may be complicated by dental cavities)
- Skin and vaginal dryness
- Joint pain, stiffness and swelling
- Muscle pain
- Enlarged "glands" (lymph nodes or salivary glands)
- Cough and shortness of breath
Conditions other than Sjögren's syndrome can cause these symptoms. For example, dry mouth can be a side effect from a medicine. Normal aging can be linked with dry eyes and dry mouth. So, if you have these symptoms, it's important to have a thorough medical evaluation.
What Can I Expect Looking to the Future?
As this latest research shows, there is mystery not only regarding why autoimmune disease develops but also about when it starts. The finding of autoantibodies years before illness suggests that these conditions may be "brewing" long before anyone is aware.
Future research may clarify why autoantibodies appear years before disease in many people with autoimmune disease, including those with Sjögren's syndrome. And that could lead to discoveries about the causes of these disorders and ways to prevent them.