Faster, more accurate diagnostic test for Sjogren's syndrome

Researchers in Japan are developing a faster, more accurate diagnostic test for Sjögren’s (SHOW-grins) syndrome, an incurable autoimmune disorder characterized by chronically dry eyes and dry mouth.

The noninvasive test, which analyzes multiple protein biomarkers in the tears using highly sensitive mass spectrometry, shows promise in early clinical studies as the first simple test for identifying the disease, the scientists say.

Sjögren’s affects between 1 million and 4 million Americans, primarily women over age 40. April is Sjögren’s Syndrome Awareness Month.

The study will be described in the June 13 print issue of the American Chemical Society’s Journal of Proteome Research, a peer-reviewed publication. ACS is the world’s largest scientific society.

Current methods to diagnose the disease involve a battery of tests, including painful invasive techniques using needles or biopsies to analyze bodily tissues and fluids, particularly in the eyes and mouth. Because of the complexity of the disease and its similarity to other disease symptoms or drug-induced conditions, Sjögren’s can be difficult to diagnose. Diagnosis of the disease has been further complicated by the lack of biomarkers specific for the disease as well as its slow progress, the researchers say.

According to study leader Naohisa Tomosugi, M.D., of Kanazawa Medical University in Japan, the new painless technique would require that patients shed as little as a single teardrop, collected in a doctor’s office using special filter papers. The teardrop would then be analyzed in the laboratory for newly discovered protein biomarkers and results can be obtained in as little as one hour, Tomosugi says. The test, which is being refined, could be available to consumers in two to three years, he estimates.

“The development of an accurate and noninvasive diagnostic test [for Sjögren’s] would be of considerable value in the clinical field,” Tomosugi says. Early diagnosis is considered key to reducing the severity of disease symptoms and its complications, which can include debilitating fatigue and joint pain. Although the disease has no cure, its symptoms can be minimized with a variety of medications, including anti-inflammatory drugs and special moisture replacement therapies for dryness.

In the current study, Tomosugi and his associates analyzed the protein content of tears obtained from 31 patients diagnosed with Sjögren’s syndrome (on the basis of conventional tests) and compared the results to protein markers obtained from the tears of 57 subjects who did not have the syndrome. Using a new analytical technique called surface enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS), the researchers identified about 10 protein biomarkers that appear to be specific for Sjögren’s.

In addition to helping diagnose the disease, the tear biomarkers also show potential for noninvasive monitoring of disease activity and progress, the researchers say. The biomarkers may also provide insights into the underlying mechanisms of the syndrome, such as those involving inflammation and glandular destruction, they say.

The exact cause of the condition is unknown. In general, researchers believe that the immune system attacks the glands that produce tears and saliva, resulting in dry mouth and dry eyes. Although the disease is generally not life-threatening, it can produce serious symptoms, including fatigue, difficulty swallowing, joint pain and eye problems. Because its symptoms often accompany other conditions, such as arthritis or lupus, and vary among individuals, the disease is often misdiagnosed or undiagnosed.