New centromere autoantigens identified in systemic sclerosis using centromere protein microarrays.

OBJECTIVE

To identify novel centromere protein (CENP) targets of anticentromere antibodies (ACA), and to investigate their association with clinical manifestations of systemic sclerosis (SSc).

METHODS

A CENP-focused protein microarray was fabricated by spotting 14 purified CENP. These microarrays were individually incubated with 35 ACA-positive SSc sera and 20 ACA-negative healthy control samples. Newly identified CENP autoantigens with high sensitivities were selected for validation and characterization.

RESULTS

Statistical analysis revealed 11 CENP are potential target antigens of ACA in patients with SSc. Of them, 5 [CENP-P, CENP-Q, CENP-M (isoform I), CENP-J, and CENP-T] are novel, among which CENP-P and CENP-Q showed high sensitivities in ACA-positive SSc sera of 34.3% and 28.6%, respectively. Subsequently, 186 SSc sera (35 ACA-positives and 151 negatives), 69 ACA-positive sera from other various autoimmune diseases (primary Sjögren syndrome, systemic lupus erythematosus, rheumatoid arthritis, and primary biliary cirrhosis), and 31 healthy sera were assayed for the presence of anti-CENP-P and -Q autoantibodies by ELISA followed by Western blotting analysis. CENP-P and -Q autoantibodies were detected in ACA-positive sera of various disease groups; among them, SSc showed the highest detection rate. Anti-CENP-P was also found in 9 of the 151 ACA-negative sera. Analyses of the correlation with clinical information showed anti-CENP-P-positive patients had higher levels of IgG, IgA, and erythrocyte sedimentation rate among the ACA-positive cohort and were more vulnerable to renal disease in the ACA-negative patients with SSc. Regardless of ACA status, anti-CENP-P or Q-negative patients seem to be predominantly affected by interstitial lung disease.

CONCLUSION

CENP-P and CENP-Q were identified as novel ACA autoantigens by CENP microarray assays followed by validation of ELISA and Western blotting. Both of them have prognostic utility for interstitial lung disease. CENP-P was associated with renal disease in an ACA-negative cohort.