An existing drug might be able to treat an autoimmune disorder that causes dry eye, dry mouth, fatigue and muscle or joint pain.
Baricitinib (Olumiant), a drug currently used to treat rheumatoid arthritis, appears to effectively curb the symptoms of Sjögren’s disease, according to results from lab mice published in a new study.
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The drug does this by suppressing the malfunctioning immune signals that drive Sjögren’s, researchers report in the journal Science Translational Medicine.
“Not only did we dissect the underlying cause for Sjögren’s disease in our mouse model, but we correlated these findings to the disease’s classification criteria and genetic signatures in humans,” senior researcher Dr. Stefan Feske, a professor of pathology at NYU Grossman School of Medicine, said in a university news release.
“Moreover, I think using baricitinib has great promise in the treatment of Sjögren’s disease going forward,” Feske added.
Sjögren’s disease occurs when the immune system attacks the glands that produce saliva and tears, resulting in dry mouth and eyes, researchers said.
Patients can also experience fatigue, joint and muscle pain, rashes and lung inflammation.
It’s the second most common rheumatic autoimmune disease in the United States, three times more common than related diseases like lupus and multiple sclerosis, according to the Sjögren’s Foundation.
As many as 4 million Americans — 1 in every 70 people — are affected by Sjögren’s, the foundation says.
“Not being able to produce tears or saliva can have a great impact on one’s life,” researcher Rodrigo Lacruz, a professor of molecular pathobiology at NYU College of Dentistry, said in a news release.
“If you can’t produce saliva, it may hamper your speech and your ability to process food, increases your risk for developing cavities, and overall worsens one’s health,” Lacruz added.
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Researchers decided to focus on salivary gland cells and immune cells to better understand the mechanisms that cause Sjögren’s.
They discovered that an inflammatory chemical produced by the immune system, interferon gamma, appears to interfere with saliva production in mice.
Interferon gamma levels are typically held in check by T cells that regulate immune response, researchers said.
But if a genetic defect inhibits T cell function, too much interferon gamma is produced, resulting in symptoms similar to those of Sjögren’s, results show.
“It came down to a defect in regulatory T cells and an over-activation of the cells that produce an inflammatory cytokine called interferon gamma,” Feske said. “Interferon gamma was absolutely critical for causing dysfunction of salivary glands in our mouse model.”
Given that, researchers figured that a drug that suppresses interferon action might be able to treat Sjögren’s.
To see if this might work in humans, researchers examined blood samples from patients with Sjögren’s.
They found a strong correlation between mice and humans regarding the underlying genetics of Sjogren’s, results show.
However, clinical trials will be needed to prove that baricitinib or some other JAK inhibitor can effectively treat Sjogren’s, researchers concluded.