Causes of Sjögren’s Syndrome

Sjögren’s syndrome is an autoimmune disorder primarily characterized by inflammation of the tear and salivary glands, leading to the condition’s signature symptoms of dry eyes and mouth.

Experts don’t know for sure what causes Sjögren’s syndrome, but some believe that a combination of genetics and an infection causes the immune system to start mistakenly attacking the body’s own cells.

Sjögren’s syndrome can affect anyone but tends to appear more often in women over 40. People who develop the disease on its own, without any underlying condition, are said to have primary Sjögren’s syndrome, while secondary Sjögren’s syndrome develops in those with another autoimmune disease.

Without a known cause, treatments for Sjögren’s syndrome focus on alleviating symptoms. These include eye drops and oral solutions that mimic saliva.

Autoimmunity

The immune system works to defend the body against foreign invaders, such as viruses and bacteria. Its job is essentially to attack anything that could cause disease, while leaving a person’s healthy tissue unharmed.

In autoimmunity, however, the immune system erroneously recognizes the person’s own cells as a foreign threat, and launches an inflammatory attack against those cells. In people with Sjögren’s syndrome, the immune system first targets the glands that make tears and saliva, but other parts of the body — such as joints, nerves, skin, kidneys, liver, and lungs — can also become damaged.

One way that the immune system fights foreign threats is by producing specialized proteins called antibodies, which bind to a particular molecule and signals to other parts of the immune system that a threat is present, prompting an inflammatory response.

Sjögren’s syndrome is characterized by the presence of autoantibodies — antibodies that mistakenly recognize healthy tissue, leading to autoimmunity — sometimes years before symptoms are evident. The autoantibodies most commonly associated with Sjögren’s are anti-Ro (SS-A) and anti-La (SS-B) antibodies, but there are others.

While a majority of Sjögren’s syndrome have autoantibodies against these nuclear proteins, healthy people also commonly test positive for these antibodies, suggesting that other factors are at play.

Risk factors

It is thought that Sjögren’s arises from a complex mix of genetic and environmental factors.

The disease is 12 times more common among relatives of Sjögren’s patients than in the general population, pointing to a genetic component. While certain genes increase a person’s risk for Sjögren’s syndrome, other factors, such as viral or bacterial infections, appear necessary for sending the immune system into overdrive.

A person’s age and sex also seem to influence their susceptibility to Sjögren’s syndrome, as the disease is usually diagnosed between the ages of 45 and 69, and nine out of 10 patients with the condition are women. It is still unclear why Sjögren’s syndrome affects more women than men, but some believe that sex hormones might play a role.

Those at risk also include people who already have an autoimmune disease, such as rheumatoid arthritis or lupus, which might share some disease mechanisms with Sjögren’s.

 

Last updated: May 3, 2021

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