Clinical Immunology focuses on the immune system’s health. Learn about the diagnosis and treatment of allergies, autoimmune diseases, and immunodeficiencies.
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Sjögren syndrome is a long-term autoimmune disease where the immune system attacks the body’s own moisture-producing glands, especially the tear and saliva glands. This causes inflammation, damage, and reduced ability to make tears and saliva. While dry eyes and dry mouth are the main symptoms, the disease can affect almost any organ, such as the lungs, kidneys, liver, pancreas, and nervous system. Both B-cells and T-cells in the immune system are involved in this process. To truly understand Sjögren syndrome, it’s important to look at the underlying immune changes that cause ongoing inflammation.
The main problem in Sjögren syndrome starts in the lining of the moisture-producing glands. Normally, these glands make fluids that protect the body’s surfaces. In Sjögren syndrome, the cells in these glands attract immune cells from the blood. These immune cells, mostly T helper cells and B cells, gather in groups and release substances that cause inflammation and cell death in the glands. These substances also interfere with the nerves that signal the glands to make moisture, so the glands stop working even before they are completely damaged.
A key part of Sjögren syndrome is that B-cells, which make antibodies, become overactive. They produce autoantibodies, such as Anti-SSA (Ro) and Anti-SSB (La), that attack the body’s own cells. This overactivity can cause immune complexes to build up in organs, leading to problems like blood vessel inflammation and kidney damage. Over time, the constant stimulation of B-cells also raises the risk of developing B-cell lymphomas.
The medical community categorizes Sjögren syndrome into two distinct clinical entities based on the presence or absence of other rheumatic conditions.
Primary Sjögren syndrome happens on its own, without any other autoimmune connective tissue diseases. People usually have dry eyes and dry mouth, but they may also feel tired, have joint pain, or problems with other organs. Diagnosis is often delayed because symptoms can be slow to appear and may be confused with aging or side effects from medicine. Studies show that primary Sjögren syndrome may have a stronger genetic link and a different pattern of autoantibodies than the secondary type.
Secondary Sjögren syndrome develops in patients who already have an established autoimmune disease, most commonly Rheumatoid Arthritis (RA), Systemic Lupus Erythematosus (SLE), or Systemic Sclerosis (Scleroderma). In these cases, the symptoms of dryness are superimposed on the existing clinical picture of the primary condition. For example, a patient with Rheumatoid Arthritis may gradually develop gritty eyes and difficulty swallowing. Distinguishing between primary and secondary is essential for treatment, as the management of the underlying condition often overlaps with the therapy for Sjögren-related symptoms.
Sjögren syndrome is among the most prevalent autoimmune diseases, yet it remains under-recognized.
Sjögren syndrome affects women about nine times more often than men, making it one of the most gender-skewed diseases. This suggests that hormones like estrogen and prolactin play a big role. The drop in estrogen during menopause, which is when the disease often starts, may trigger symptoms in women who are genetically at risk. Men who get the disease may have different symptoms, often with less fatigue but more severe organ problems.
Sjögren syndrome can appear at any age, even in children, but it is most common in people in their 40s and 50s. It is often diagnosed in women around menopause. Because symptoms develop slowly, many people have mild problems for years before getting a clear diagnosis.
While Sjögren syndrome is not a hereditary disease in the simple sense, genetic predisposition is a key risk factor. Genome-wide association studies have identified several loci associated with the disease. The most consistent associations are with the Human Leukocyte Antigen (HLA) complex, specifically HLA-DR3 and HLA-DQ2 alleles. These genes are involved in how the immune system presents antigens to T-cells. Variations in genes related to interferon signaling (such as IRF5 and STAT4) also contribute to the heightened immune alertness seen in patients. However, genetics is not destiny; studies of identical twins show that one may develop the disease while the other does not, highlighting the necessity of environmental triggers.
The “mosaic of autoimmunity” theory suggests that environmental factors act as a catalyst in genetically predisposed individuals.
Viral infections are the most suspected triggers. Viruses such as Epstein-Barr Virus (EBV), Hepatitis C, and Human T-cell Lymphotropic Virus Type 1 (HTLV-1) have been studied extensively. These viruses have a tropism for salivary gland tissue, meaning they naturally infect these cells. It is hypothesized that a viral infection damages the gland cells, releasing hidden antigens that the immune system then attacks. Even after the virus is cleared, the immune system remains in a hyper-alert state, perpetuating the attack on the glands through a mechanism known as molecular mimicry.
New research suggests that an imbalance in the bacteria of the mouth and gut, called dysbiosis, may play a role in Sjögren syndrome. The bacteria in these areas help train the immune system. When saliva is reduced, the balance of bacteria in the mouth changes, which can lead to more inflammation. Changes in gut bacteria may also contribute to the body-wide inflammation seen in this disease.
Doctors learn the most about Sjögren syndrome by looking at gland tissue under a microscope. The main finding is called ‘focal lymphocytic sialadenitis,’ which means clusters of immune cells gather around the salivary gland ducts and replace healthy tissue. The more clusters there are, the more severe the disease. Over time, ongoing inflammation destroys the fluid-producing parts of the gland, which are replaced by scar tissue and fat. This is why, in advanced cases, medicines that try to stimulate the glands may not work, because the working tissue is gone.
Sjögren syndrome is correctly classified as a connective tissue disease because the inflammation targets the stromal framework that supports organs. This can lead to non-specific systemic symptoms that can be debilitating. Inflammation of the connective tissue in the joints causes synovitis, though it is usually non-erosive, unlike Rheumatoid Arthritis. Inflammation of the connective tissue in the muscles causes myositis. The disease can also affect the connective tissue of the blood vessels, leading to vasculitis, which impairs blood flow to nerves and skin. This systemic nature underlines the fact that Sjögren syndrome is a whole-body disease, necessitating a holistic medical approach.
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It is an autoimmune reaction where immune cells attack moisture-producing glands, likely triggered by a combination of genetics and environmental factors like viruses.
No, it is actually quite common, ranking as the second or third most common rheumatic autoimmune disorder, though it is frequently undiagnosed.
Hormonal differences, particularly the effects of estrogen and genetics related to the X chromosome, are believed to make women more susceptible.
It is rarely fatal directly. However, complications like lung fibrosis or lymphoma can be life-threatening, requiring careful monitoring.
Dry eyes can be caused by screens, aging, or weather. Sjögren syndrome is a systemic inflammatory disease where dry eyes are just one symptom of widespread immune dysfunction.
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