Different SSc-specific Autoantibodies May Dictate Disease’s Presentation

Different types of systemic sclerosis-related autoantibodies may lead to different presentations of the disease, and affect distinct groups of internal organs, research suggests.

The study reporting the findings, “Clinical Manifestation and Incidence of Cardiopulmonary Complications in Early Systemic Sclerosis Patients with Different Antibody Profiles,” was published in the Journal of Clinical Medicine Research.

Previous evidence indicated that the autoantibody profile of people with systemic sclerosis (SSc) is associated with clinical manifestations of the disease, organ system involvement, prospect of disease management, and patient survival.

Screening for the presence of two specific autoantibodies — anti-topoisomerase I (ATA) and anti-centromere antibodies (ACA) — is routine in general clinical practice for the early diagnosis of SSc.

Research suggests that SSc patients who are ATA-positive more frequently develop the diffuse cutaneous form of the disorder, sores on the fingers or toes, interstitial lung disease, pulmonary hypertension, and have joint, tendon and/or heart problems, compared to ACA-positive patients.

Importantly, “ATA-positive subset has been associated with more severe organ involvement and poorer clinical outcome than the ACA-positive subset,” the researchers stated.

However, not much is known about SSc clinical manifestations and the incidence rate of cardiopulmonary complications in distinct autoantibody profiles.

To address this question, a research team at Chiang Mai University, in Thailand, investigated the differences between initial clinical presentation and cumulative organ involvement, as well as the incidence rate of cardiopulmonary complications in ATA-positive, ATA-negative, and ACA-positive early SSc patients.

In total, 114 subjects (45 men and 69 women) were evaluated. Patients had a mean disease duration of 11.7 months at the beginning of the study. All participants underwent electrocardiography, echocardiography, and high-resolution computed tomography at study entry, and then again annually, to assess the heart’s structure and functioning.

Ninety of the 114 patients analyzed had diffuse cutaneous SSc; “of the 114, there were 89 patients (78.1%) who were ATA-positive, 18 (15.8%) ATA-negative, and seven (6.1%) ACA-positive,” the researchers said.

At the beginning of the study, those with and without ATA were more likely to have the diffuse cutaneous subtype and interstitial lung disease, in comparison to those who were ACA-positive.

At the end of the follow-up period (mean duration of 3.8 years), the team observed that ATA-positive SSc patients had a higher cumulative prevalence of digital ulcers, limited range of joint motion, and tendon abnormalities. A higher frequency of pulmonary changes, including interstitial lung disease, was detected in both the ATA-positive and ATA-negative groups, compared to ACA-positive patients.

Regarding the incidence of cardiac changes, no significant differences were found among the three autoantibody profiles. Nonetheless, cardiopulmonary abnormalities were found to be more common in the ATA-positive and ATA-negative groups. No heart complications were found in the ACA-positive group.

In conclusion, the “presence of SSc-specific autoantibodies was associated with a distinctive clinical presentation and cumulative internal organ involvement, even in the early phase of the disease,” the researchers said.

“Cardiopulmonary complications were rarely seen in the ACA-positive group; whereas [interstitial lung disease] complications were very common in both the ATA-positive and ATA-negative groups,” they added.

According to the team, further research is needed to better understand the association among cardiopulmonary complications, interstitial lung disease, and autoantibodies in SSc patients.