Certain antibodies tied to poorer outcomes in systemic sclerosis
Study suggests isolated anti-SSA antibodies could help guide closer monitoring
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Having anti-SSA antibodies, without other common scleroderma-related antibodies present, is linked to shorter survival and faster disease progression in people with systemic sclerosis (SSc), according to a recent study from Japan.
“These findings support the inclusion of anti-SSA in routine serologic [blood] assessment and underscore the potential utility of ‘isolated’ anti-SSA seropositivity as a marker of higher-risk [scleroderma],” the researchers wrote.
The study, “Isolated Anti-SS-A Antibody Seropositivity as a Poor Prognostic Factor in Systemic Sclerosis: Insights From a Cohort of 307 Cases,” was published in The Journal of Dermatology.
How anti-SSA antibodies may relate to lung disease in SSc
SSc, or scleroderma, is an autoimmune disease in which an overactive immune system leads to inflammation, blood vessel damage, and scarring of the skin and internal organs.
Previous research has suggested that anti-SSA antibodies, which are also found in autoimmune diseases such as Sjögren’s disease and systemic lupus erythematosus, are linked with a higher risk of serious internal organ involvement. This includes interstitial lung disease (ILD), a condition in which inflammation and scarring in the lungs makes breathing more difficult.
To better understand this link, researchers at The University of Tokyo, in Japan, conducted a retrospective analysis of 307 people with SSc who were first evaluated between January 2011 and March 2020. The group had an average age of 55.3, had been living with the disease for about six years, and was mostly female (89%). Nearly one-third (31.3%) tested positive for anti-SSA antibodies.
Other SSc-related autoantibodies were also common, including anti-centromere antibodies (33%) and anti-topoisomerase 1 (ATA) antibodies (35%). Anti-U1 ribonucleoprotein antibodies were present in about 10% of the overall group, and were more frequent in people who had anti-SSA antibodies than in those who did not (18% vs. 7%).
A significantly higher proportion of people with anti-SSA antibodies were also more likely to have other autoimmune diseases, including systemic lupus erythematosus (7% vs. 2%) and Sjögren’s disease (38% vs. 9%). Telangiectasias — widened blood vessels visible near the skin surface — were also more common (51% vs. 36%).
ILD was also more common in people with anti-SSA antibodies (62.5% vs. 36%). Lung involvement tended to be more severe, based on higher blood levels of KL- 6 and SP-D — markers of lung injury — and lower %DLco, a measure of how well oxygen moves from the lungs into the bloodstream.
Taken together, these findings support “the association of anti-SSA with pulmonary involvement and systemic [body-wide] inflammation.”
Those with only anti-SSA antibodies may benefit from closer monitoring
Overall, 20 people had isolated anti-SSA positivity, meaning they tested positive for anti-SSA antibodies but did not have other major SSc-related antibodies. Among this group, five also had Sjögren’s disease, four had inflammatory muscle disease, and one had antiphospholipid antibody syndrome — a condition where the immune system makes antibodies that increase blood-clot risk.
People with isolated anti-SSA antibodies had a 21.7 times higher risk of shorter survival and a 4.2 times higher risk of earlier disease progression. Among the four patients whose disease worsened, all treatment changes were made because of ILD. Five patients in this group died from causes that included COVID-19 infection, myocarditis (inflammation of the heart muscle), and ILD.
According to the researchers, “our data suggest that the absence of concomitant SSc-related autoantibodies may mark a unique subgroup with particularly aggressive disease trajectories from a longitudinal observation of a Japanese cohort.”
Shorter survival was also linked to scleroderma renal crisis and the absence of nail fold bleeding. Meanwhile, earlier ILD progression was associated with isolated anti-SSA positivity, ATA positivity, and diffuse skin sclerosis (widespread skin thickening and tightening).
“These results emphasize the need for expanded serologic profiling and vigilant clinical monitoring in this unique subgroup, which appears especially prone to aggressive organ involvement and early disease progression,” the researchers wrote. “Future prospective studies should clarify whether therapeutic interventions tailored to high-risk autoimmune profiles can improve outcomes in patients who present with isolated anti-SSA seropositivity.”
