Sjögren’s syndrome is a systemic autoimmune disease, where the tear and salivary glands are attacked and destroyed by the body's own immune cells. This results in the characteristic symptoms of dry eyes and dry mouth. Patients with Sjögren’s syndrome are mostly women and often have antibodies in their blood which can be passed via the placenta to stop their baby’s heart from working (neonatal heart block). Sjögren’s syndrome is often associated with other systemic autoimmune diseases such as Raynaud’ phenomenom, rheumatoid arthritis, SLE, scleroderma and mixed connective tissue disease. Some patients have enlarged lymph glands and spleens and may develop a type of cancer later in life called lymphoma.
In Sjögren’s syndrome, immune cells infiltrate and destroy the mucus-producing glands of the body. It is thought that several factors – including viral infections, hormones, genetics and stress – trigger autoimmune diseases. 90% of people with Sjögren’s syndrome are women: on average they are diagnosed between 40 and 50 years of age.
What is an autoimmune disease?
The immune system is the body’s defence system against small microbial pathogens such as bacteria and viruses. However, for unknown reasons, the immune system sometimes mistakes parts of the body as belonging to a bacteria or virus and attacks it. In Sjögren’s syndrome, the immune diseases system mostly attacks exocrine glands such as tear and salivary glands. However, it can also attack the central and peripheral nervous system.
Autoimmune diseases affect approximately one in 20 people in Western countries. Sjögren’s syndrome, lupus, rheumatoid arthritis, and Type 1 diabetes are all examples of autoimmune diseases.
What are the signs and symptoms of Sjögren’s syndrome?
The symptoms vary greatly between individuals and may include:
- Dry eyes and few or no tears - the most frequent complaint is the sensation of a foreign body in the eye. Redness, burning, light sensitivity, eye fatigue and itching may also be present
- Dry mouth - difficulty chewing, swallowing food or speaking are signs of a dry mouth. Ulceration of the tongue and cheek membranes, a burning feeling of the tongue, altered taste sensation and the need to frequently drink fluids are common
- Bacterial over growth in the mouth - saliva is important for its antibacterial function, so without adequate saliva, dental decay, periodontal disease and oral yeast infections may develop
- Dry ear and nose - this may result in eustachian problems in the middle ear or crusts, bleed and a reduced sense of smell in the nose
- Fatigue and/or depression
- Vaginal dryness - recurrent vaginal infections and pain during intercourse may develop if lubricants are not used
- Swelling and pain in the joints
- Numbness and pins and needles
- Muscle weakness
- Nausea, vomiting, early satiety and abdominal bloating
- Kidney stones
What approaches to treatment are available?
Sjögren’s syndrome is often diagnosed by the demonstration of decreased tear or saliva production and the presence of elevated levels of total and specific antibodies in the serum of patients with characteristic symptoms and signs. These antinuclear antibodies (ANA) are directed against parts of the nucleus of the cell called SSA and SSB antigens and can be found in the majority of patients with Sjögren’s syndrome. Patients with SSA antibodies may pass it on to their unborn babies via the placenta and special tests and precautions are necessary to manage the pregnancy to diagnose and treat this rare complication.
There is currently no cure for Sjögren’s syndrome and treatment is aimed at symptomatic relief. A variety of artificial tear preparations can be used to treat dry eyes. There are some oral lubricants for treating symptoms of a dry mouth, but none are entirely satisfactory. Chewing sugarless gum is helpful for some people. Good dental hygiene and frequent visits to the dentist are essential. Some patients take a prescription medicine called pilocarpine which can stimulate glands to make more tears and saliva.
What research is Garvan doing in this area?
The Garvan Institute is home to one of the largest immunology research programs in Australia. Apart from Sjögren’s syndrome, we also research rheumatoid arthritis, lupus, Type 1 diabetes, inflammatory bowel disease, and various lymphomas and leukemias. Our immunologists use advanced techniques (such as gene profiling of diseased tissue samples and sophisticated methods of purification of immune cells) to identify new factors responsible for immune disorders.
Sjögren’s syndrome is a disease in which antibodies develop against parts of a patient’s own cells. It is believed to be caused by improper regulation of two immune cell types, T and B cells, which comprise the ‘adaptive’ half of the immune system. These types of white blood cells can react to and “adapt” to generate an immune response that specifically attacks a foreign substance, such as a bacteria.
The adaptability of this response means that it can attack an incredibly wide range of pathogens and this type of activity also leads to long-lived memory of the immune system. Unfortunately, dysregulation of this type of response can lead to the emergence of long-lived cells that produce antibody against “self”, such as those that occur in Sjögren’s Syndrome. Recently, we identified new triggers for some sub-forms of Sjögren’s.
Garvan’s scientists have shown that many patients suffering from Sjögren’s syndrome have high levels of something called B cell-activating factor (BAFF) in their blood serum, as well as locally in their glands. BAFF plays a critical role in the response of anti-body producing “B cells” . We have now demonstrated that high levels of BAFF enable B cells to progress the disease without the help of T cells, which was previously thought to be essential for the development of Sjögren’s syndrome.
This is an important breakthrough that will allow Garvan scientists to develop a new generation of therapeutic agents for Sjögren’s syndrome that specifically target auto-reactive B cells. Patients who have this form of the disease will then be able to trial more tailored and effective treatments. Other groups in the Garvan are still working on understanding the basis for the development of pathogenic antibodies in autoimmune diseases like Sjögren’s syndrome.
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