Sjögren syndrome is an autoimmune disease, which means that the immune defence attacks some of the body’s own cells by mistake. This causes a chronic inflammatory condition which targets the body’s glands – especially the saliva and tear glands. The symptoms include dry eyes and dry mucus membranes, and this discomfort occurs periodically. A reduced saliva production increases the risk of dental decay, and it can make it difficult to swallow certain types of dry food. The dry eyes can feel as if there is sand in them – they sting, and it hurts to blink. The eyes easily become tired, irritated and red, and they are easily heavily affected by draughts or smoke. The disease is systemic, which means that it can affect the entire body. Some patients also suffer from muscle and joint pain, dry skin, reddish rashes and sluggish stools. Some women also experience dry vagina. The disease can also cause damage to other organs, herein the kidneys, liver and brain. Sjögren syndrome can be secondary to arthritis, whereof about one third of patients with arthritis also suffer from Sjögren syndrome.
How is Sjögren syndrome diagnosed, and can it be treated?
As the nuisances are diffuse and intermittent and the main symptoms – dry eyes and dry mucus membranes – also are signs of many other conditions, the diagnosis is usually not made until many years later. The disease is most common in two age groups, 20-30 years and after the age of 55, but it is usually diagnosed in the 30-50-year mark.
The diagnosis is made if 4 out of 6 of the following criteria are met:
- Reduced tear production
- Dry eyes
- The saliva gland functions unusually
- Dry mouth
- A tissue sample from a saliva gland indicating changes that are common to this disease.
- If there are autoimmune substances in the blood
Today, there is no specific treatment for Sjögren syndrome, but there are drugs that can reduce some of the symptoms. According to researcher, Sarah Hamm-Alvarez from the University of Southern California Roski Eye Institute, an earlier diagnosis and treatment may be able to prevent many of the serious, systemic influences which the disease has caused and possibly be able to prevent serious damage and loss of gland tissue.
New knowledge of Sjögren syndrome may simplify the process of making a diagnose
A group of scientists from the University of Southern California Roski Eye Institute, herein Sarah Hamm-Alvarez, believes that certain changes within the tear production occur before the tear production begins to drop. In a study, where the researchers investigated lachrymal fluid or ‘tear fluid’ from patients with Sjögren syndrome, the results showed that a specific protein – cathepsin S’ – was only detected in patients with Sjögren syndrome, contrary to those without the disease. The researchers believe that the presence of the protein is associated with the changed tear production which is seen in patients with the condition. This experience may help doctors diagnose the condition earlier on.
In the lachrymal fluid in patients with Sjögren syndrome, the amount of cathepsin S was high. This protein is capable of breaking down other proteins and helping cells dispose of waste. People without the disease, but who still suffered from dry eyes, did not have cathepsin S in their lachrymal fluid. Based on this discovery, scientists believe that cathepsin S can be used as a biomarker for Sjögren syndrome, whereby a diagnosis can be made faster.
In the study, the researchers searched for an explanation to this connection. They examined two proteins that are involved in the tear production in genetically modified mice – the proteins ‘Rab3D’ and ‘Rab27.’ The mice, lacking the gene for Rab3D, had more cathepsin S in their lachrymal fluid, while mice, lacking the gene for Rab27, had less cathepsin S in their lachrymal fluid. The results show that Rab3D and Rab27 can counteract each other’s effects on the tear production. Loss of Rab3D may increase the effects caused by Rab27, which contributes to an increased level of cathepsin S secretion in patients with Sjögren syndrome.
The new drug for Sjögren syndrome
Non-clinical studies (animal experiments) have tested a drug which can inhibit cathepsin S, and the results have shown that the drug is effective against Sjögren syndrome. An investigation of patients with Sjögren syndrome is now underway to establish if the same effect can be seen in humans. The drug will be tested for its effect on dry eyes but also for its pharmacological effects as well as its influence on the immune system. The study has included 70 test subjects with primary Sjögren syndrome, whereof half will be treated with cathepsin S-inhibitors for 12 weeks, while the rest will receive a placebo.
A different study with 30 test subjects will investigate the effect of the drug on saliva glands and the inflammatory condition in the body. The studies will take place in USA and Europe. These patients therefore have the opportunity to receive treatment with a new drug for Sjögren syndrome before anybody else. The drug had been tested on animals and thoroughly examined for any harmful effects long before these clinical studies could begin. The animal experiments showed that the treatment is highly effective.
