Abilene Reporter-News June 25, 2013
By Drs. David Niesel and Norbert Herzog
First the eyes feel dry, so dry the sensation is like having sand in them. Then the mouth dries out so that it’s hard to swallow. While the symptoms come on slowly, the disease is usually diagnosed after it’s too late. By then, the patients’ salivary glands and tear glands are already destroyed and there is little that can be done. But researchers are trying to change that by developing a test that could diagnose Sjogren’s Syndrome (SS) earlier.
As the third most common autoimmune disorder in the U.S., SS affects about 4 million Americans, most of them women and over 40. Autoimmune disorders result from a person’s own immune system attacking the body. The worst part is that there’s no cure for SS.
The disease first attacks the mucous membranes and moisture-secreting glands, causing dry eyes and mouth, which are treated with over-the-counter, and prescription medications. However, this disease is systemic, affecting many parts of the body including the brain, kidneys, liver, lungs, skin and nerves among others. A person with SS can end up seeing a host of specialists including rheumatologists and dentists to come up with an individualized treatment plan using immunosuppressive therapies to treat this complex disease. They also face a 5 to 15 percent chance of developing lymphomas as the disease progresses.
Diagnosis of SS includes blood tests to measure antibodies frequently associated with autoimmune disorders, ophthalmological tests for tear production and dryness of the surface of the eye and additional tests to measure salivary gland function. A biopsy to check for signs of inflammation may also be done. Diagnosis is based on having a combination of symptoms and results of the various lab tests. Currently, there is no known test to definitively diagnose the disease.
But now researchers have developed a test that could diagnose SS much sooner, before the damage sets in. Since it is very rare to diagnose humans in the early stages of SS, researchers had to first develop an animal model of SS in mice that closely resembles the disease in humans. This allowed researchers to look for markers of the disease as it progressed. They discovered elevated levels of messenger RNAs that code for three salivary gland proteins in SS mice. They also found that the SS mice were making antibodies against these three proteins, in effect attacking themselves — the hallmark of an autoimmune disorder.
They then detected the same autoantibodies in human SS patients. So, the new test works by measuring the levels of these three types of unique antibodies in the blood. Antibodies, Y-shaped proteins produced by the immune system, recognize and bind to antigens, substances that the body flags as foreign or harmful, like bacteria and viruses.
These newly identified autoantibodies appear much earlier, providing an opportunity for earlier and more definitive diagnosis. Earlier diagnosis may allow doctors to start therapies that may save SS patients’ salivary and tear glands, alleviating their symptoms and slowing the progression of SS.
Medical Discovery News is a weekly radio and print broadcast highlighting medical and scientific breakthroughs hosted by professor emeritus Norbert Herzog and professor David Niesel, biomedical scientists at the University of Texas Medical Branch at Galveston. Learn more at www.medicaldiscoverynews.com.