Anti-Carbamylated Protein Antibodies Linked to SLE Disease Activity

Anti-carbamylated protein (anti-CarP) antibodies may be associated with disease severity in patients with systemic lupus erythematosus (SLE), according to study results published in Lupus.

The study included patients with SLE (n=100; 90% women; mean age, 33.65±11.31 years), rheumatoid arthritis (n=76), primary Sjögren syndrome (n=17), and healthy control participants (n=68). Using enzyme immunosorbent assay, the researchers measured serum levels of anti-CarP antibodies. They used primary Sjögren syndrome software for Windows to perform data analysis between anti-CarP antibodies and other laboratory measures.

Compared with healthy control participants, patients with SLE had significantly higher levels of anti-CarP antibodies (4.4% vs 25%; P <.01). Among patients with SLE who did not show disease-specific antibodies, anti-CarP antibodies were present, including among patients whose test results showed anti-Smith-negative (24.4%; n=21/86), anti-dsDNA-negative (29.3%; 12/41), anti-nucleosome-negative (21.4%; n=9/42), and antiribosomal P protein antibody-negative (23.7%; n=18/76).

Researchers found significant differences in clinical and laboratory features among patients with SLE who tested as anti-CarP-positive and anti-CarP-negative. After adjusting for age and disease duration, high levels of anti-CarP antibodies were associated with low red blood cell count, low hemoglobin, high erythrocyte sedimentation rate, high immunoglobulin G, and high third-generation cyclic citrullinated peptide.

Compared with patients with inactive disease, patients with active SLE showed higher anti-CarP immunoglobulin G levels. In addition, compared with patients with SLE without arthralgia and/or arthritis, patients with SLE with arthralgia and/or arthritis had significantly higher levels of anti-CarP antibodies.

Limitations included the study’s single-center design and relatively small sample size, which could have contributed to association bias.

“Anti-CarP could provide a potential supplement to other specific antibodies for diagnosis of SLE and serve as a promising marker to measure joint damage in SLE,” the researchers wrote.

Reference

Li Y, Jia R, Liu Y, et al. Antibodies against carbamylated vimentin exist in systemic lupus erythematosus and correlated with disease activity. Lupus. doi:10.1177/0961203319897127