Distinct symptom pattern found for triple-negative scleroderma patients
Those without 3 common antibodies have some issues but not others
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People with scleroderma who are triple autoantibody-negative — meaning they don’t have three common disease-associated antibodies — are more likely to experience muscle damage and lung disease than others with the rare condition, a new study shows.
Conversely, data indicate that patients negative for the three antibodies are less likely to experience disease complications that affect the blood vessels, according to the researchers. In addition to their distinct symptoms, treatment patterns differed significantly in this subset of patients, the scientists noted.
“Our data suggest that triple negativity identifies a further subset of patients with [scleroderma] with a definite diagnosis characterized by clinical features different from those of patients with [systemic scleroderma] positive for at least one disease-specific autoantibody,” the researchers wrote.
The team concluded that these triple-negative patients “represent a distinct [scleroderma subtype].”
The study, “Clinical and serological features of triple autoantibody-negative patients with systemic sclerosis: insights from the multicentric SPRING registry of the Italian Society for Rheumatology,” was published in the journal RMD Open.
Scleroderma, also called systemic sclerosis or SSc, is an inflammatory disorder that’s marked by fibrosis, or scarring, that can affect various tissues throughout the body. The disease is thought to be caused by abnormal activation of the immune system. In particular, studies have shown that many people with SSc test positive for autoantibodies, or antibodies that attack the body’s own healthy tissue.
Three specific types of autoantibodies have been linked with SSc: those targeting antitopoisomerase I (ATA), anticentromere (ACA), and anti-RNA polymerase III (RNAP3). However, some patients meet all the diagnostic criteria for SSc, but don’t test positive for any of these three disease-associated autoantibodies. Such patients are said to be triple-seronegative.
Researchers used data from national registry in Italy
Using data from a national registry in Italy, a team of scientists in that European nation now set out to evaluate how clinical manifestations of triple-seronegative SSc compare with signs and symptoms seen for patients who have at least one of those three autoantibodies.
“To the best of our knowledge, this is the largest study assessing the prevalence of triple-negative patients with SSc in the Italian population, analyzing data from a large multicenter cohort of patients with SSc involving 38 Italian referral centers,” the scientists wrote.
Altogether, the study involved data from 1,480 people with SSc. Most were positive for autoantibodies targeting ATA and/or ACA, with a few positive for autoantibodies against RNAP3. About 1 in 5 patients were triple-seronegative.
Rates of muscle damage, as evidenced by symptoms of muscle weakness and/or elevated markers of muscle damage, were significantly higher in triple-seronegative patients compared with those who were positive for at least one autoantibody (17% vs. 10%).
Triple-seronegative patients also had significantly higher rates of interstitial lung disease, which broadly refers to disorders that cause scarring in the lungs. Consistent with the higher rates of lung disease, tests of lung function were generally worse in triple-seronegative individuals. Worse lung function was also seen in a subset of patients who were negative for the three main autoantibodies and also absent antinuclear antibodies — another type of autoantibody that’s associated with various inflammatory diseases.
Data also showed that the triple-seronegative group had significantly lower rates of certain blood vessel complications. These included sores on the fingers and toes known as digital ulcers (17% vs 23%), as well as abnormal deposits of calcium in the skin and other soft tissue, called calcinosis (8% vs 13%).
“A higher prevalence of [muscle damage and interstitial lung disease], and reduced burden of vascular complications are frequently found in the triple-negative patients,” the researchers wrote.
Immune-suppressing meds more likely for triple-negative patientsÂ
Treatment patterns also differed based on autoantibody status. The triple-negative patients were significantly more likely to be on certain immune-suppressing or immunomodulating medications, namely corticosteroids, cyclophosphamide, hydroxychloroquine, and azathioprine.
At the same time, they were less likely to be on certain blood pressure medicines, including calcium channel blockers and PDE5 inhibitors. The lower rate of blood pressure meds is consistent with lower rates of blood vessel complications among the triple-seronegative patients, the researchers noted.
The scientists said these data overall support the notion that triple-seronegative patients make up a distinct subset of SSc patients requiring specific care strategies. The team called for further research into this specific patient population.
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