[Significance of anti-tubulin-α-1C autoantibody in systemic sclerosis]

Objective: To detect the serum level of a novel autoantibody, anti-tubulin-α-1C, in patients with systemic sclerosis (SSc) and to investigate its clinical significance.

Methods: Anti-tubulin-α-1C antibody levels were determined by enzyme-linked immunosorbent assay (ELISA) in 62 patients with SSc, 38 systemic lupus erythematosus (SLE), 24 primary Sjögren's syndrome (pSS) patients, and 30 healthy controls (HCs). Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), immunoglobulin A(IgA), immunoglobulin M (IgM), immunoglobulin G (IgG), C3, C4, rheumatoid factor (RF), antinuclear antibody(ANA), anti-centromere antibodies(ACA), anticardiolipin (aCL), anti-dsDNA antibody, anti-Sm antibody, anti-RNP antibody, anti-Scl-70 antibody, anti-Ro52 antibody, anti-SSA antibody, anti-SSB antibody, centromere protein A(CENP-A), centromere protein B (CENP-B) were measured by standard laboratory techniques. Raynaud's phenomenon and modified Rodnan skin score(MRSS) were recorded to evaluate the disease status of SSc. Independent sample t test, Chi square test, Mann-Whitney U test, Spearman rank correlation were used for statistical analyses.

Results: The serum anti-tubulin-α-1C antibody concentration in SSc group was 81.24±34.38, the serum anti-tubulin-α-1C antibody concentration in SLE group was 87.84±38.52, the serum anti-tubulin-α-1C antibody concentration in pSS group was 59.79±25.24, and the serum anti-tubulin-α-1C antibody concentration in healthy group was 39.37±18.7. Multivariate analysis revealed that anti-tubulin-α-1C antibody levels were significantly increased in the SSc and SLE patients. The expression level of anti-tubulin-α-1C antibody in SSc was higher compared with the pSS group and the health control group (P < 0.01). Further analysis demonstrated that the elevated anti-tubulin-α-1C antibody were correlated with the SSc inflammation and disease activity markers ESR(r=0.313, P=0.019), The levels of anti-tubulin-α-1C antibody were also significantly correlated with MRSS(r=0.636, P < 0.01). The best cut-off value for the diagnose of SSc was 76.77 as mean+2SD value. The proportion of Raynaud's phenomenon was higher in the group of anti-tubulin-α-1C autoantibody-postive SSc patients than that in anti-tubulin-α-1C autoantibody negative group(71.4% vs. 37.5%, P=0.039). The proportions of anti-Scl-70 antibody, anti-CENP antibody and anti-cardiolipin antibody were higher in the group of anti-tubulin-α-1C autoantibody-postive SSc patients than in the anti-tubulin-α-1C autoantibody negative group (37.9% vs. 15.2%, 34.5% vs. 12.1%, 13.8 vs. 0, respectively, all P < 0.05).

Conclusion: Based on this explorative stu-dy, the level of anti-tubulin-α-1C antibody increased in the serum of the patients with SSc. There were correlations between anti-tubulin-α-1C autoantibody and clinical and laboratory indicators of the SSc patients. It may become a novel biomarker indicative of active SSc and could be applied in future clinical practice.